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 ASSESSMENT AND OPTIMIZATION OF OCCUPATIONAL RADIATION DOSES 
IN FLUOROSCOPY GUIDED PROCEDURE AT KORLE - BU TEACHING 
HOSPITAL, ACCRA, GHANA 
 
BY 
RUTH NANA NJANTANG 
(10633004) 
 
A THESIS SUBMITTED TO THE DEPARTMENT OF MEDICAL PHYSICS 
SCHOOL OF NUCLEAR AND ALLIED SCIENCES 
UNIVERSITY OF GHANA 
 
IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE AWARD OF 
MASTER OF PHILOSOPHY DEGREE 
 IN  
NUCLEAR SCIENCE AND TECHNOLOGY 
 
JULY, 2018 
 
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DECLARATION 
“This thesis is a result of a research work undertaken by Ruth Nana Njantang in the 
department of Medical Physics, School of Nuclear and Allied Sciences, University of 
Ghana, under the supervision of Prof. Mary Boadu and Mr. Prince Kwabena Gyekye.” 
I hereby affirm that except for references which have been cited, this work is the product 
of my own research and it has not been presented in part or whole for any other degree in 
this University or elsewhere.  
 
……..…………..……..                        Date……….…………….. 
Ruth Nana Njantang  
Student     
 
Certified by: 
 
 
……………….………….                 Date…………………… 
Prof. Mary Boadu                  
Principal Supervisor)           
 
 
…………………….…    Date……………………. 
Mr Prince Kwabena Gyekye  
Co-Supervisor 
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ABSTRACT 
International Commission on Radiological Protection (ICRP) publication 85 of 2000 
recommended the use of two dosimeters for the monitoring of staff performing 
fluoroscopically guided procedures. This study aimed to assess the dose to operators 
performing fluoroscopically guided procedures at Korle – Bu Teaching Hospital and 
evaluate possibility for dose reduction. Four Radiologists, the Interventional Radiologist 
and the assistant were monitored for a period of one month and four Cardiologists were 
monitored for two months. Two electronic dosimeters were used by each worker present 
in the room and the personal equivalent dose Hp (10) and Hp (0.07) were recorded after 
each procedure. The Kerma Area Product (KAP) and screening time were also recorded 
per procedure. The scattered radiation dose rate was measured using a water phantom at 1 
m from the focal spot, 160 cm from the floor at 0°, 90°, 120° and 180° for 3 projection of 
the tube (RAO 30°, LAO 30° and AP 0°). The patient dose and screening time at 
Radiology Department (over couch tube) were [1.89 - 14.38] Gy.cm², (0.2 -2.5) min; 
[3.76 – 44.16] Gy.cm², (0.3 – 3.1) min and [8.7 – 60.77] Gy.cm², (1.9 – 10.9) min for 
Retrograde Urethrogram (RUG), Hysterosalpingography (HSG) and special cases 
respectively. The patient dose and screening time range at Cardiology (under couch tube) 
were [14.24 – 120.61] Gy.cm², (1.7 – 16.3) min, [42 – 237] Gy.cm², (9.70 – 43) min and 
[4.37 – 33.56] Gy.cm², (4.30 – 11.8) min for Coronary Angiogram (CA), Percutaneous 
Coronary Intervention (PCI) and Right Heart Catheterization (RHC) respectively. The 
dose range per procedure to Cardiologists was [0.1 – 42.15] µSv, [1.2 – 31.2] µSv and 
[0.1 – 2.75] µSv for the CA, PCI and RHC respectively.  The range of the estimated 
monthly effective dose, and eye lens dose to Cardiologists and Radiologists were [0.01 – 
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0.07] mSv, (0.15, 0.30) mSv and [0.03 – 0.12] mSv, (0.53 – 3.39) mSv respectively. The 
interventional procedures were found to be lengthier with exposure time of (52 – 76.4 
min), and delivered relatively high dose (47.13 – 412.23 Gy.cm²) to patients. The 
Interventional Radiologist and the assistant received an effective dose of 0.09 mSv, 0.03 
mSv respectively and eye lens dose of 1.2 mSv, 0.33 mSv respectively. A weak but 
significant relationship (R² = 0.32, p-value < 0.05) was found to exist between patient 
dose and staff effective dose, meaning that staff dose is influence by other factors. 
Generally, the staff effective dose and eye lens dose to Cardiologists and Radiologists 
were below the acceptable limits (1.67 mSv/month) excerpt for one Radiologist whose 
eye lens dose exceeded the limit by a factor of 2. Therefore, the use of a ceiling 
suspended screen is highly recommended in radiology to reduce the eye lens dose. Monte 
Carlo simulation of the distribution of radiation in the room highlighted the safest 
position that can be occupied by the staff as dose reduction technique to reduce the dose. 
The Implementation of the proposed radiation safety programme is encouraged for 
optimization of protection in both departments.  
 
 
 
 
 
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DEDICATION 
This work is dedicated to the Strength of my life, My Heavenly Father, the Almighty 
GOD. 
 
 
 
 
 
 
. 
 
 
 
 
 
 
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ACKNOWLEDGEMENTS 
Special thanks go to the General Director of National Radiation Protection Agency of 
Cameroon Dr. Augustin Simo and Prof. Maurice Moyo Ndontchueng who offered me the 
opportunity to be trained in Ghana. I also want to express my gratitude to International 
Atomic Energy Agency (IAEA) for the sponsorship of this program. 
I would like to acknowledge the Director General of Ghana Atomic Energy Commission 
(GAEC) Prof. B. J. Nyarko, Dean, Prof. Yaw Serfor-Armah, the Head of International 
Programmes, Dr. Dennis Adotey, the Head of Medical Physic Department, Dr. Francis 
Hasford, all the staff and Nuclear Science and Technology Programme (NSTP) lecturers 
of the School of Nuclear and Allied Science. Also, I thank the Nuclear Regulatory 
Authority, Radiological and Medical Sciences Research Institute and Radiation 
Protection Institute of GAEC for the provision and calibration of the equipment. 
Special thanks go to my supervisors, Prof. Mary Boadu and Mr. Prince. K. Gyekye for 
their supportive and constructive criticism. Sincere gratitude goes to Prof. Cyril 
Schandorf for his useful advises and critical import which added value to this work. 
I would like to show my appreciation to the administration, Radiologists team, 
Radiographers, Nurses and Cardiologists team of Korle-bu Teaching Hospital for good 
collaboration. Particular thanks go to Mr. Bernard Botwe who facilitated my access to the 
facility and guided me throughout the data collection. 
 Heartfelt gratitude goes to my family and friends for all their encouragement. I am 
indebted to Mr. Joseph and Mrs. Marian DADSON for their great love and support. 
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TABLE OF CONTENTS 
 
DECLARATION........................................................................................................ ii 
ABSTRACT ............................................................................................................... iii 
DEDICATION............................................................................................................ v 
ACKNOWLEDGEMENTS ..................................................................................... vi 
TABLE OF CONTENTS ........................................................................................ vii 
LIST OF FIGURES ................................................................................................ xiii 
LIST OF TABLES ................................................................................................... xv 
LIST OF ABBREVIATIONS ............................................................................... xvii 
CHAPTER ONE ........................................................................................................ 1 
1.0. Introduction ................................................................................................... 1 
1.1. Background to the study ................................................................................ 1 
1.2. Statement of the Problem .............................................................................. 3 
1.3. Research Objective ........................................................................................ 4 
1.4. Relevance and justification ........................................................................... 5 
1.5. Scope and Delimitation ................................................................................. 5 
CHAPTER TWO ....................................................................................................... 7 
2.0. Literature Review .......................................................................................... 7 
2.1. Physics behind Fluoroscopy: X-ray Production and Interaction ................... 7 
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2.1.1. X-ray production .................................................................................... 7 
2.1.2. X-ray Interactions with Matter............................................................... 8 
2.2. Technology and Mode of Operation of the Fluoroscopy Machine ................. 10 
2.2. Occupational Radiation Protection.............................................................. 13 
2.3.1. Source of Occupational Radiation ....................................................... 14 
2.3.2. Quantities used in Radiological Protection .......................................... 15 
2.3.3. Operational Quantities for Individual and Area Monitoring ............... 17 
2.3.4. Radiation Effects and Radiation Protection Principles ........................ 17 
2.4. Strategies to Reduce Radiation Risk to Staff .................................................. 22 
2.4.1. Practical Application of Optimization of Protection ................................ 24 
2.4.2. Education and Training Programs ............................................................ 25 
2.5. Individual Monitoring ..................................................................................... 25 
2.5.1. Passive dosimeters .................................................................................... 26 
2.5.2. Active Personal Dosimeters (APDs) ........................................................ 26 
2.6. Assessment of Occupational Exposure ........................................................... 27 
2.6.1. Effective Dose Assessment ...................................................................... 27 
2.6.2. Assessment of Equivalent Dose to the Lens of the Eye ........................... 29 
CHAPTER THREE ................................................................................................. 30 
3.0. Material and Method ....................................................................................... 30 
3.1. The Study Area................................................................................................ 30 
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3.1.1. Radiology Department of KBTH ............................................................. 31 
3.1.2 National Cardiothoracic Centre (NCTC) ................................................... 32 
3.2. Sample Size ..................................................................................................... 34 
3.3. Materials .......................................................................................................... 34 
3.3.1. Questionnaire ............................................................................................ 34 
3.3.2. Piranha ...................................................................................................... 34 
3.3.3. Kerma Area Product Meter ....................................................................... 36 
3.3.4. Electronic Personal Dosimeter (EPD) ...................................................... 37 
3.3.5. Dose Rate Meter ....................................................................................... 41 
3.4. Software .......................................................................................................... 43 
3.4.1. Microsoft Excell ....................................................................................... 43 
3.4.2. Simple Geo ............................................................................................... 43 
3.4.3. Monte Carlo N Particle (MCNP) .............................................................. 44 
3.5. Methods ........................................................................................................... 45 
3.5.1. Quality Control (QC) Tests ...................................................................... 45 
3.5.2. Dose Monitoring ....................................................................................... 48 
3.5.3. Scatter Radiation Study in the Examination Room .................................. 49 
3.5.4. Data Analysis ............................................................................................ 50 
3.5.5. Monte Carlo Simulation ........................................................................... 55 
CHAPTER FOUR .................................................................................................... 56 
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4.0. Results and Discussions .................................................................................. 56 
4.1. Basic Elements of Radiation Protection in Both Department ......................... 56 
4.2. Quality control results ..................................................................................... 59 
4.2.1. Over couch Fluoroscopy in Radiology Department ................................. 59 
4.2.2. Under couch Fluoroscopy in Cathlab ....................................................... 62 
4.3. Patients and Radiologists Dose in Radiology Department.............................. 65 
4.3.1. Patient Dose and Fluoroscopy Time ......................................................... 66 
4.3.2. Radiologist Dose and Workload ............................................................... 67 
4.4. Patients and Cardiologists Dose in Cathlab .................................................... 74 
4.4.1. Patient Dose and Fluoroscopy Time ......................................................... 75 
4.4.2. Cardiologists Doses .................................................................................. 76 
4.4.3. Risk Assessment to Cardiologists ............................................................. 81 
4.4.4. Relationship between Effective Dose and Patient Dose ........................... 82 
4.5. Investigation into other Factors affecting Workers Dose................................ 83 
4.6. Scattered Radiation in the Examination Room (Cathlab) ............................... 85 
4.6.1. Modelling of the room .............................................................................. 85 
4.6.2. Distribution of Radiation in the Room for AP 0° of the Source .............. 86 
4.6.3. Distribution of Radiation in the Room for LAO 30° and RAO 30° of the 
Source ................................................................................................................. 89 
4.6.4. Measured Values of the Scattered Radiation ............................................ 90 
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4.7. Limitations of the study................................................................................... 91 
CHAPTER FIVE ..................................................................................................... 92 
5.0. Conclusion and Recommendations ................................................................. 92 
5.1. Conclusion ....................................................................................................... 92 
5.2. Recommendations ........................................................................................... 93 
5.2.1. Establishment of a Radiation Safety Programme ..................................... 94 
5.2.2. Recommendation for Further Study ......................................................... 94 
REFERENCES ......................................................................................................... 96 
APPENDIX 1: Approval Letters .......................................................................... 105 
APPENDIX 2: Data Collection Sheet ................................................................... 109 
APPENDIX 3: Questionnaire ............................................................................... 110 
APPENDIX 4: Calibration Certificates ............................................................... 112 
APPENDIX 5: Quality Control Results from Pirhana ....................................... 115 
APPENDIX 6: Radiation Safety Programme for Occupationally Exposed Workers 
in Fluoroscopy Guided Procedure ........................................................................ 118 
1.0. Introduction ............................................................................................... 118 
2.0. Responsibilities ......................................................................................... 118 
3.0. Individual Monitoring ............................................................................... 119 
4.0. Occupational Radiation Protection and Equipment .................................. 121 
5.0. Education and Training ............................................................................. 122 
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6.0. Quality Assurance ..................................................................................... 123 
7.0. Records for Quality Improvement............................................................. 123 
8.0. Pregnant Workers .......................................................................................... 124 
9.0. Emergency Plan and Procedures ............................................................... 124 
APPENDIX 7: Typical Monte Carlo Input File .................................................. 126 
APPENDIX 8: Raw Data of the Simulation Results ........................................... 133 
 
 
 
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LIST OF FIGURES 
Figure 2.1: The X-ray tube ........................................................................................... 8 
Figure 2.2: Photon interaction with the tissue www.e-radiography.net ...................... 9 
Figure 2.3: Exponential attenuation of photon energy in the material ...................... 10 
Figure 2.4: Schematic of the fluoroscopic imaging chain ......................................... 11 
Figure 2.5: An image intensification tube.................................................................. 12 
Figure 2.6: Sources of occupational radiation exposure ............................................ 14 
Figure 3.1:  Location of KBTH in Greater Accra Region ......................................... 30 
Figure 3.2: Over couch fluoroscopy machine at the Radiology Department ............ 32 
Figure 3.3: Outlook of the actual NCTC at KBTH .................................................... 33 
Figure 3.4: Internal view of cathlab with Siemens biplane fluoroscopy unit. ........... 33 
Figure 3.5: Setup of QC tools (Piranha and ocean 2014 installed on a computer) under the 
x – ray system ..................................................................................................... 35 
Figure 3.6: (a) The kerma X – plus with the separated reader and (b) The ion chamber 
fixed on the X – ray tube in Radiology Department........................................... 37 
Figure 3.7: Electronic Personal Dosimeters used for this study ................................ 38 
Figure 3.8: Calibration setup in SSDL at GAEC ....................................................... 38 
Figure 3.9: Typical personal dosimeter  (source: www.helmholtz-muenchen.de) .... 39 
Figure 3.10: Dose rate meter used in this study ......................................................... 41 
Figure 3.11: Functional parts of the dose rate meter (source: www.polimaster.com)42 
Figure 3.12: Microsoft excell 2010 running on window 7 ........................................ 43 
Figure 3.13: Simple GEO interface with an example of geometry created (theis et al., 
2006) ................................................................................................................... 44 
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Figure 3.14: Radiograph from the beam collimation check ...................................... 46 
Figure 3.15: Cathlab dimensions ............................................................................... 49 
Figure 3.16: Schematic of the side view of measurement set - up ............................ 50 
Figure 3.17: Schematic of the top view of the measurement set-up showing the point of 
measurements at different angles at 1m from the isocenter. .............................. 50 
Figure 4. 1: Estimated effective and eye lens dose compared with ICRP limit 73 
Figure 4. 2: Frequency of procedures in the cathlab .................................................. 74 
Figure 4. 3: Number of procedure conducted by Cardiologists monthly .................. 77 
Figure 4.4: Estimated effective dose and eye lens dose to Cardiologists for different type 
of procedure ........................................................................................................ 78 
Figure 4.5: Estimated annual effective dose and eye lens dose compared to ICRP limits
 ............................................................................................................................ 80 
Figure 4.6: Estimated risk to Cardiologists................................................................ 81 
Figure 4.7: Relationship between effective dose and patient dose ............................ 82 
Figure 4.8. Source, patient table and phantom modeled with simple GEO software 85 
Figure 4. 9. Top and side view of the cathlab modeled with simple GEO software. 85 
Figure 4.10: Dose distribution in the room at 85 cm from the floor .......................... 86 
Figure 4.11: Dose distribution in the room at 107 cm from the floor ........................ 86 
Figure 4.12: Dose distribution in the room at 150 cm from the floor ........................ 87 
Figure 4.13: Dose distribution in the room at 171 cm from the floor ........................ 88 
Figure 4.14: Dose distribution (LAO 30°) at 171 cm from the floor ......................... 89 
Figure 4.15: Dose distribution (RAO 30°) at 171 cm from the floor ........................ 90 
 
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LIST OF TABLES 
Table 2.1: Risk coefficients for stochastic effect proposed by ICRP (𝟏𝟎 − 𝟐 𝑺𝒗 − 𝟏). 
(ICRP, 2007) ....................................................................................................... 19 
Table 2.2: ICRP’s recommendations for dose limits (ICRP, 2007;   ICRP, 2013) ... 21 
Table 2.3: Dose reduction techniques that are commonly used interventional cardiology 
procedures (miller et al, 2010) ........................................................................... 23 
Table 3.1: Specifications of the black piranha for radiography / fluoroscopy 36 
Table 3.2: EPD MK 2+ radiological specifications ................................................... 40 
Table 3.3:  EPD MK 2+ environmental specifications .............................................. 41 
Table 3.4: Characteristic of the dose rate meter ........................................................ 42 
Table 3.5: Some of the algorithm proposed for effective dose calculation with thyroid 
collar [adapted from jarvinen et al. (2008) and ICRP (2018)] ................................... 51 
Table 3.6: Ratio (eye lens / thyroid) doses [adapted from carinou et al. (2015)] ...... 53 
Table 4. 1: Status of radiation protection measure in both departments……...…….57 
Table 4.2: kVp, time and output reproducibility test. ................................................ 60 
Table 4.3: Tube voltage accuracy .............................................................................. 60 
Table 4.4: mAs linearity ............................................................................................ 60 
Table 4.5: Summary of the results ............................................................................. 62 
Table 4.6: Voltage, time and output reproducibility test ........................................... 63 
Table 4.7: Tube voltage accuracy .............................................................................. 63 
Table 4.8: Summary of the results of QC test ............................................................ 64 
Table 4.9: Summary of procedures and dose measurements ..................................... 65 
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Table 4.10: Median and range values of KAP and fluoroscopy time for each procedure.
 ............................................................................................................................ 66 
Table 4.11: Estimated daily effective dose (using three different methods) and eye lens 
dose to RAD 1 .................................................................................................... 68 
Table 4.12: Estimated daily effective dose (using three different methods) and eye lens 
dose to RAD 2 for HSG procedures ................................................................... 69 
Table 4.13: Estimated daily effective dose (using three different methods) and eye lens 
dose to RAD 3 for HSG procedures. .................................................................. 69 
table 4.14: estimated daily effective dose (using three different methods) and eye lens 
dose to RAD 4. ................................................................................................... 70 
Table 4.15: Estimated monthly workload, effective dose and eye lens dose to the 
Radiologists. ....................................................................................................... 71 
Table 4.16: Number of procedures performed by cardiologists during the period of data 
collection. ........................................................................................................... 74 
Table 4.17: Median and range values of KAP and fluoroscopy time for each procedure 
performed in Cathab. .......................................................................................... 75 
Table 4.18: Effective dose per procedure to Cardiologists ........................................ 76 
Table 4.19: Monthly effective dose and eye lens to the Cardiologists ...................... 79 
Table 4.20: Dose records of interventional radiology procedures with overcouch and 
undercouch tube. ................................................................................................. 84 
Table 4.21: Measured values of scattered radiation ................................................... 90 
 
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LIST OF ABBREVIATIONS 
    
IAEA                 International Atomic Energy Agency 
ICRU                  International Commission on Radiation Units and Measurements 
PET      Positron Emission Tomography 
QA      Quality Assurance 
WHO       World Health Organization 
NCRP                  National Council on Radiation Protection 
CONRAD            European Coordinated Network for Radiation Dosimetry 
HSG                     Hysterosalpingogram  
IVU                      Intraveneous Urogram 
MCUG                  Mituriting Urethrogram 
RUG                      Retrograde Urethrogram 
CT                        Computed Tomography 
MRI                      Magnetic Resonance Imaging 
NCTC                   National Cardiothoraxic Center 
QC                        Quality Control 
RTI                       Radiation To Information 
USB                      Universal Serial Bus 
RAMSRI              Radiological and Medical Science Institute 
GAEC                  Ghana Atomic Energy Commission 
HVL                     Half Value Layer 
LCD                     Liquid Crystal Display 
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EPD                      Electronic Personal Dosimeter 
MCNP                  Monte Carlo N - Particle 
LED                    Light Emitting Diode 
OEW                  Occupationally Exposed Worker 
NM                     Nuclear Medicine 
TLD                   Thermoluminescent Dosimeter 
OSL Optical Simulated Luminescence  
ICRP                  International Commission on Radiological Protection 
ALARA             As Low As Reasonable Achievable 
KBTH                Korle Bu Teaching Hospital 
CCD                   Charge – Coupled Device 
Cs I                     Cesium Iodine 
BSS                     Basic Safety Standard 
Gy                       Gray 
mA       milli Ampere 
kVp                     kilo Voltage peak 
KAP       Kerma Area Product 
DAP       Dose Area Product 
Sv       Sievert 
BEIR                   Biological Effect of Ionizing Radiation 
DDREF               Dose and Dose Rate Effectiveness Factor 
LSS                      Life Span Study 
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UNSCEAR          United Nation Scientific Committee of the Effect of Atomic     
Radiation 
DD                       Doubling Dose 
IEC                   International Electrotechnical Commission 
APD                     Active Personal Dosimeter 
CA                       Coronary Angiography 
PCI                       Percutaneous Coronary Intervention 
RHC                     Right Heart Catheterization 
NRC                     National Research Council 
RSO                      Radiation Safety Officer       
LAO                      Left Anterior Oblique 
RAO Right Anterior Oblique 
AP                         Anterior Posterior 
LANL                     Los Alamos National Laboratory 
ISO                        International Organization for Standardization 
IRPA International Radiation Protection Association 
DNA  Deoxyribonucleic Acid 
CathLab  Catheterization Laboratory 
SSDL  Secondary Standard Dosimetry Laboratory 
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AHA American Heart Association 
ACC American College of Cardiology 
 NRA Nuclear Regulatory Authority 
 
 
 
 
 
 
 
 
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CHAPTER ONE 
1.0. Introduction 
In the introductory part of this study, the background, the statement of the problem, 
justification, objectives and scope of the study are clearly defined. 
1.1. Background to the study 
Medical exposure from X-rays and nuclear medicine is the largest man-made source of 
radiation exposure, representing a mean effective dose of 1.0–3.0 mSv per head per year 
(Mettler et al, 2009). The worldwide population exposure from medical radiation has 
been shown to increase, and the use of procedures (both diagnostic and therapeutic) with 
a high radiation dose has been growing steadily (Kim et al, 2008; Vano et al, 2009; 
Vassileva et al, 2013). Radiation exposure is a significant concern for interventional 
cardiologists and patients due to the increasing workloads and the complexity of 
procedures over the last decade (ICRP, 2013). 
With fluoroscopy the patient is imaged in real time to guide minimally invasive 
procedures that form part of the diagnostic and interventional procedures, and this 
requires medical and technical staff to directly participate in the procedures. 
Occupationally Exposed Workers (OEWs) in fluoroscopy procedures are likely to 
receive high exposure, especially for the unshielded parts of the body which are: the 
extremities and head (Vano et al, 2010; Vano et al, 2013). Rehani et al (2010) 
reported lens opacities detected among some Interventional Radiologists and 
Cardiologist. The primary operator who stays closer to the patient is the most exposed 
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to radiation among all staff present in the room during interventional procedures (Kong 
et al, 2015). Many studies have been done so far concerning occupational exposure 
in fluoroscopy guided procedures around the world, mostly in Europe and America 
(Sanchez, 2011; Sandblom et al, 2013; Kostas et al, 2016; Szumska et al, 2016). A 
study performed in Netherlands, has estimated median occupational effective dose at 
3 µSv per procedure for the interventional radiologist,  0.4 µSv per procedure for 
the assistant radiologist and maximum occupational effective dose for technologists 0.4 
mSv (Joemai, 2009).  
Radiation safety in the practice of interventional cardiology has been addressed by 
several professional bodies. UNSCEAR in 2008 report states that fluoroscopic 
procedures represent the largest source of occupational exposure in medicine 
(UNSCEAR, 2008). In 2009, the American Heart Association (AHA) Science Advisory 
recommended the reference doses of common cardiology examinations (Gerber et al, 
2009) and in 2010 the American College of Cardiology (ACC) committee also expressed 
the need for appropriate and optimal use of radiation techniques in cardiology (Brindis 
and Douglas, 2010). 
The continuous and systematic use of adequate protective equipment such as protective 
apron, thyroid shield, lead gloves, protective glasses, ceiling-suspended glass screen 
and lead curtain can significantly reduce exposure to the workers directly involved in 
interventional procedures. However, study on detailed monitoring of OEWs in 
fluoroscopy guided procedure in many facilities is still lacking. Botwe et al (2015) in a 
study carried out at the biggest referral hospital in Ghana showed that the radiation 
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monitoring of staff was unsatisfactory and did not meet required standard and stated that 
workers were monitored by the means of TLD badges only.  
1.2. Statement of the Problem 
Among all medical staff, those performing fluoroscopically guided procedures (such as 
Cardiologists and interventional radiologists.) are likely to receive the highest exposure 
to ionizing radiation. The eye’s lens, extremities and thyroid can receive high radiation 
doses (Ciraj-Bjelac et al, 2010; Vano et al, 2010; Ciraj-Bjelac et al, 2012; Vano et al, 
2013). The eye lens exposure results in the prevalence of lens opacities and cataracts 
among Cardiologists, Radiologists. This indicates the relevance of optimization of 
radiological protection in fluoroscopically guided procedures (Sandblom et al, 2013). 
Unlike other activities involving ionizing radiation, for which the exposure of the staff is 
predictable (optimization can be performed in advance), optimization of radiation 
protection in interventional radiology is complex and has to be performed during the 
procedure under varying and sometimes difficult situation such as unstable patient who 
require individual care. The nature of the procedures, the high individual workload and 
the difficulties in radiation protection measures justify the need for detailed 
occupational dosimetry studies.  Studies performed in Ghana on fluoroscopy 
examinations were focused on patient dosimetry (Gyekye et al. 2009; Gyasi et al. 
2012). The survey of literature indicates that there is no empirical data available on dose 
estimation of individuals working in specific fluoroscopy guided procedures in Ghana. 
In National Cardiothoracic Center, according to the patient data available in book record, 
the number of procedures has grown from 15 procedures / year (2000 – 2010) to 25 – 30 
procedures / year (2011 – 2015). With the installation of the new cathlab in October 
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2016 the number of procedures has increased up to (22 – 24) procedures monthly. This 
increasing number of procedures shows the importance of intensifying personal 
monitoring programme at the Center. In addition, the International Commission on 
Radiological Protection in the statement on tissue reactions on 21 April 2011 
recommend for occupational exposure in planned exposure situations, the revised 
equivalent dose limits for the lens of the eye are 20 mSv in a year, averaged over 5 
consecutive years (i.e. 100 mSv in 5 years), and 50 mSv in any single year. These limits 
replace the previous limit on equivalent dose of 150 mSv in a year and the threshold in 
absorbed dose is now considered to be 0.5 Gy (ICRP, 2011; IAEA, 2014).  
1.3. Research Objective 
This study aims to estimate dose to medical staff during fluoroscopically guided 
procedures and evaluate possibilities for dose reduction. 
 
The specific objectives of the study include the following: 
 Estimate eye lens and effective dose to medical staff during selected fluoroscopy 
guided procedures. 
 Use Monte-Carlo simulation to investigate the radiation dose distribution in the 
room to evaluate the possibilities of dose reduction. 
 Investigate the factors that influence staff doses such as workload, type of 
procedure, patient dose, etc. 
  Assess detrimental risk to the workers and propose recommendations aimed at 
staff dose reduction for clinical routine. 
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1.4. Relevance and justification 
The purpose of routine monitoring for occupational exposure is to verify and 
demonstrate compliance with the regulatory or international dose limits, provide 
information on dose levels for the optimization of protection, to keep the dose as low as 
reasonably achievable (ALARA) and identify working practices that minimize the doses. 
The findings of this study on occupational doses will serve as a baseline data for future 
dose optimization efforts in fluoroscopically guided procedures in Ghana and may 
trigger the effective implementation of a radiation protection programme. Additionally, 
this study is going to help understand the influence of staff doses by the type of 
procedure performed, the individual workload, the use of radiation protection tools and 
the methodology of dose measurement. Lastly, staff dose reduction techniques 
suggested from this study for clinical trials will aid in the optimization of staff protection. 
1.5. Scope and Delimitation  
This research covered staff performing fluoroscopically guided procedures whilst 
standing in the examination room in radiology and cardiology departments at the Korle-
Bu Teaching Hospital (KBTH). For investigative studies, Monte Carlo N-Particle code 
was used to effectively experiment on possible staff dose reduction techniques. The 
radiation exposure to the staff’s whole body, eye lens and the study of the scatter 
radiation in the room of examination will be the dosimetry scope. 
This study is limited to the dosimetry of the staff and does not include patient protection. 
The dosimetry of the staff is also only limited to the whole body and eye lens exposures 
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and does not include any other organs. Only fluoroscopically guided procedures in the 
radiology and cathlab of the KBTH were considered.      
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CHAPTER TWO 
2.0. Literature Review 
This chapter present the general physics behind fluoroscopy: basic science, optimal use, 
Patient and operator protection. The principle of dose measurements and risk associated 
with radiation is described. 
2.1. Physics behind Fluoroscopy: X-ray Production and Interaction  
X-ray was discovered in 1895 when Wilhem Conrad Roentgen noticed that a screen 
coated with a barium-compound glowed when it was subjected to what would later me 
named X-rays. It is a form of electromagnetic waves generating enough radiation to be 
ionizing. Other electromagnetic waves include visible light, radio waves and gamma rays 
(Davros, 2007).  
2.1.1. X-ray production 
X-rays are generated when the energy state of an electron change. This is achieved when 
a heated filament (cathode) produces electrons which are accelerated to a tungsten target 
(anode) by applying a high voltage (50 – 150 kVp) to the tube. The electron creates an 
electric field that interacts with other atomic particles of the anode material. This result in 
the release of energy in the form of X-ray as shown in figure 2.1. 
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Figure 2.1: The X-ray tube (Source: www.radiologymasterclass.co.uk) 
2.1.2. X-ray Interactions with Matter 
When photons pass through a material, some interacts with particle in the medium and 
their energy can be totally absorbed or scattered. Other photons travel completely through 
the medium without any interaction resulting in an image. This is called “complete 
penetration”. In diagnostic radiology, the two most important interaction of X-ray with 
tissue are: the photoelectric effect and Compton Effect. Depending on the type of 
interaction of electron with the target material, continuum and characteristic x-rays are 
produced. 
2.1.2.1. Total absorption or photoelectric effect 
This occurs when a low energy (low kVp) photon transfers the totality of its energy to the 
inner shell electron of the atom. This electron is ejected from the atom leaving a vacancy 
on the shell. An electron from an outer shell (more energetic) drops down to fill the 
vacancy. This results in an emission of characteristic X-ray. Photoelectric effect 
represents anatomic structures with high X-ray absorption characteristics, radiopaque 
structures, tissue with high atomic number, or with high mass density (bone). It 
contributes in no image and increases patient dose.  
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2.1.2.2. Compton Scattering 
Partial absorption with scatter also called Compton scatter means that part of the energy 
is absorbed by the tissue and part is scattered. Compton Effect increases with photon’s 
energy, and is likely to occur with soft tissue and fairly high energy (high kVp) photons. 
It doesn’t depend on the atomic number (probability for bone an atom is the same with 
soft tissue). Scattered radiation tends to degrade image quality and is the primary source 
of staff radiation exposure. Interaction of radiation with patient is presented in figure 2.2. 
 
Figure 2.2: Photon interaction with the tissue (www.e-radiography.net) 
 
The number of photons transmitted through the material depends on the tissue thickness, 
tissue electron density and the photon’s energy (kVp). Photon attenuation passing 
through the matter is presented in figure 1.3 below. 
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Figure 2.3: Exponential attenuation of photon energy in the material (Schuler, 2000)  
The formula that describes this curve is Beer–Lambert’s Law defined as follow equation 
(2.1): 
𝐼(𝑥) =  𝐼 𝑒−𝜇𝑥0                         (2.1) 
Where I is the initial intensity of the photon, µ is the linear absorption coefficient and x is 
the distance travelled. 
2.2. Technology and Mode of Operation of the Fluoroscopy Machine 
2.2.1 Fluoroscopic Imaging Chain 
Fluoroscopy can be defined as a general method of radiographic examination by which 
real time image is produced on the fluorescent screen when the part to be examined is 
placed between the X-ray tube and fluoroscopic screen (schueler, 2000). It allows 
observation of gross physiology, which is concerned with motion of the heart, diaphragm 
and alimentary traction, follow through and so forth. The schematic of fluoroscopy chain 
is presented in figure 2.4. 
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The principal components required for the production and management of the 
fluoroscopic images are as follows: 
 X-ray generator: produce electrical energy to the X-ray tube.  
 X-ray tube: is located under the patient table for under couch fluoroscopy unit 
and above the table for over couch fluoroscopy unit. It is fixed to the fluoroscopic tower 
and convert electrical energy from the X-ray generator to X-ray  
 
 
Monitor 
 
Video Camera 
 
Optical Coupling 
 
 
Image Intensifier 
 
 Grid 
 Patient 
Table 
 Filtration 
 Collimator 
 X-ray Tube 
X-ray  Generator 
 
 
Figure 2.4: Schematic of the fluoroscopic imaging chain 
 
 Collimation: is a device made of sets of shutters which is use to define with 
precision the area that will be irradiated. Collimation fundamental purpose is to prevent 
unwanted region of the body from being irradiated by coning down the area of interest. 
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This action thus reduces the overall patient and staff radiation dose. Proper collimation is 
important for high image quality. 
 Patient table and pad: It is used to support the patient safely during the 
examination period.  
 Image intensifier 
The image intensification tube shown in figure 2.5 receives a small portion of the 
remaining X-ray beam, converts it into a visible light image and increases the image’s 
brightness without increasing the patient dose.  
 
 
Figure 2.5: An image intensification tube 
(Source: http://www.usapa.army.mil/pdffiles/p350-59.pdf.) 
An image intensification tube has four basic components: 
- An input phosphor and photocathode: used to stop high X-ray energy that exit 
from patient and convert it into a darkish visible light image. Then convert the visible 
light photon image into free electron. 
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- Set electrostatic focusing lenses: Focus the photoelectron comprising image by a 
low potential on the inside metallic coating of the tube so that it passes through the 
anode aperture. And secondly, provide different magnification levels for viewing. 
- An accelerating anode: Accelerate the electron image to high speed by applying 
high voltage. 
- An output phosphor also made of CsI 
The electron image strikes the output phosphor and releases their kinetic energy in the 
form of massive amount of visible light photons. Thus, the output layer converts the 
electron to light necessary for visualization of the image. 
2.2. Occupational Radiation Protection  
Occupational exposure to ionizing radiation can occur in a range of industries, in mining 
and milling, in medical institutions, in educational and research establishments and in 
nuclear fuel cycle facilities. The term occupational exposure‟ refers to the radiation 
exposure incurred by a worker which is attributable to the worker’s occupation and 
received or committed during a period of work (IAEA, 2003). Persons potentially 
exposed to radiation as a result of work to more than three tenths of the occupational 
dose limit  are  occupationally  exposed  workers (OEWs) or radiation workers.  
 
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2.3.1. Source of Occupational Radiation 
In diagnostic and interventional radiology, workers are most likely exposed to three 
sources of radiations: scattered radiation, leakage radiation and direct beam show in 
figure 2.6. 
 
                       Figure 2.6: sources of occupational radiation exposure 
(Source: https://images.search.yahoo.com/scattered and leakage from x-ray.) 
 Primary radiation or useful beam: produce in the X-ray tube and it is used to 
irradiate the patient. For specific procedures worker’s hands are exposed to the direct 
beam in the case of over couch fluoroscopes. 
 Leakage radiation: are coming from the source assembly (including 
collimators). It should not exceed 1 µSv per hour at one meter when the maximum 
kiloVoltage peak (kVp) is 125 – 150 kV and maximum milli Ampere (3 – 5 mA) or at 
every power rating specified by the manufacturer.  
 Scattered radiation: arises from any object within the X-ray beam (including but 
to very limit extent, the air through which the primary X-ray beam passes). The patient 
is the most significant source of scatter radiation. The intensity of scatter is dependent 
on a number of factors, including the intensity of primary X-ray beam, the area of the X-
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ray beam incident on the patient (patient entrance skin area) and the angle from which 
the primary beam at which scatter is assessed. Scattered radiation contributes to the 
majority of occupational exposure, especially during fluoroscopy. 
2.3.2. Quantities used in Radiological Protection   
In radiation measurement, three main categories of quantities are used. The quantities 
used to describe the radiation field called radiometric quantities, include energy fluence 
(rate), fluence (ф). The dosimetric quantities which includes, absorbed dose (D), 
exposure (X), and kerma (K) and the protection quantities are equivalent dose (H), 
effective dose (E), directional dose equivalent, etc. 
2.3.2.1. Dose Quantities and Units used for Patient Dosimetry 
 Absorbed dose: 
The absorbed dose is the amount of energy imparted to the matter per unit mass of the 
irradiated material. The conventional unit is rad (Radiation Absorbed Dose) and the SI 
unit is the gray (Gy). 
1Gy = 1J/kg = 100 rad. The rate at which an absorbed dose is received is called dose rate. 
The units are Gy/s, mGy/h and the most used is µGy/h. the gray cannot be used to 
measure the relative biological effect on the body. 
 KAP (Kerma Area Product) for patient dosimetry 
Sometimes called DAP (Dose Area Product), is the dose integrated across the entire 
exposed field (dose multiplied by the area irradiated), usually expressed in Gy.cm². It is 
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measured by fixing the KAP meter on the X-ray set. The KAP is independent of the 
distance from the source. 
2.3.2.2. Dose Quantities for Occupational Exposure 
The quantities recommended by ICRP for occupational dosimetry are protection 
quantities expressed in term of effective dose and equivalent dose (ICRP, 2007). 
 Equivalent Dose 
The equivalent dose is a quantity used to indicate the relative health effect caused by a 
specific type of radiation. It is the product of the absorbed dose in the volume of organ or 
tissue (T) 𝐷𝑇,𝑅 and radiation weighting factor 𝑊𝑅 and is expressed in equation (2.2). 
                𝐻𝑇 =  ∑𝑅 𝑊𝑅 𝐷𝑇,𝑅                                                    (2.2) 
The sum is performed over all types of radiation involved. The SI Unit of equivalent dose 
is Sievert (Sv). For diagnostic radiology (𝑊𝑅 = 1) effective dose is numerically equal to 
absorbed dose. 
 Effective dose 
Defined by ICRP publication 60 as a weighted sum of tissue equivalent doses and is 
expressed in equation (2.2). 
𝐸 =  ∑𝑇 𝑊𝑇 𝐻𝑇 =  ∑𝑇 𝑊𝑇 ∑𝑅 𝑊𝑅 𝐷𝑇,𝑅                                       (2.3) 
𝑊𝑇 is the tissue weighting factor and represent also the contribution of individual organs 
and tissues to the overall radiation detriment  ∑𝑇 𝑊𝑇 = 1 .  
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The effective dose is expressed using the Sv. It is the average over all the tissues of the 
human body and is probably the most useful way to express and compare the dose 
delivered by different imaging procedures.  
These are not measurable quantities. The effective dose and equivalent dose for 
occupational exposure are assessed by using the operational quantities (ICRP, 2007a). 
2.3.3. Operational Quantities for Individual and Area Monitoring  
The operational quantities used for area monitoring of external exposure are: ambient 
dose equivalent 𝐻∗(10) and directional dose equivalent 𝐻′(0.07, Ω).  
 The quantity used for individual monitoring is personal dose equivalent 𝐻𝑃(𝑑) which is 
defined as the dose equivalent in International Commission on Radiation Units and 
Measurements (ICRU) sphere (soft tissue) at an appropriate depth d below a specified 
point on the human body. To assess the effective dose, 𝐻𝑃(10)  with d = 10 mm is used, 
𝐻𝑃(0.07) with depth d = 0.07mm for the dose to skin, the hands and the feet, and a depth 
d = 3mm is used for monitoring the dose to the lens of eye (𝐻𝑃(3). Operational quantities 
are measurable using radiation monitoring devices, which are calibrated in terms of 
𝐻𝑃(10)  and  𝐻𝑃(0.07). 
2.3.4. Radiation Effects and Radiation Protection Principles 
2.3.4.1. Radiation Effects 
X – ray is a form of ionizing radiation which once in the human body can interact with 
atoms and cause ionization in cells which may produce free radicals or direct effect that 
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can damage the Deoxyribonucleic Acid (DNA) or cause cell death. The adverse health 
effects of radiation exposure are classified into two types:  
 Deterministic effects 
Deterministic effect is defined as an outcome for which severity of the effect increases 
with dose and for which a threshold exists and are typically quite high. It is the result of a 
large part of cells kills/malfunction following high doses. Some examples are: skin 
erythema, hair loss, cataract, etc.   
 Stochastic effects 
Stochastic radiation effects involve either cancer in exposed individuals due to mutual of 
somatic cells or heritable diseases in their offspring due to mutation of reproductive 
(germ) cells. It is considered as chronic effect and caused by longer exposure relatively 
lower doses. The dose response model for stochastic effect is the linear-non-threshold 
(LNT) at low dose. The probability that cancer and heritable effects caused by radiation 
can occur increases with increment in the equivalent dose.    
- Risk of cancer 
The ICRP in publication 60 estimated cancer risk coefficient based on direct human 
epidemiological data (ICRP, 1990). Years later, the cancer risk coefficient at low dose 
and low dose rate were estimated based on many data such as occupational exposure 
(early Radiologist and Medical Physicist), medical overexposure, bomb victims, 
Inhabitants of high natural background areas, accidents, etc. Biological Effects of 
Ionizing Radiation (BEIR VII) committee combined radiobiological and epidemiological 
evidence concerning the Dose and Dose Rate Effectiveness Factor (DDREF) using data 
on solid cancer in Life Span Study (LSS) and life shortening in animals to choose the 
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modal value of DDREF as 1.5 with probabilistic uncertainties (BEIR, 2006). ICRP 
(2007) adopted the risk reduction factor of 2 for radiological protection to derive the 
nominal risk coefficient for all cancer given in table 2.1 below (ICRP, 2007a). 
- Risk of heritable effect 
The framework for the estimation of heritable risk adopted by ICRP was based on data 
from human and mouse. In publication 60, ICRP use another approach to heritable risk 
based on the concept of Doubling-Dose (DD) for disease – associated mutation (ICRP, 
1990).  In agreement with United Nations Scientific Committee on the Effects of Atomic 
Radiation (UNSCEAR, 2008) and BEIR VII, ICRP gives an estimation of the genetic risk 
up to the second generation of about 0.2% per Gray (BEIR, 2006). 
- Nominal risk coefficients for cancer and heritable effects 
ICRP in publication 103 (2007) proposed risk coefficients values for human health 
effects (cancer and heritable effects) based on calculation of sex – averaged nominal risk 
coefficient seen in table 2.1 (ICRP, 2007a).  
Table 2.1: Risk coefficients for stochastic effect proposed by ICRP (𝟏𝟎−𝟐 𝑺𝒗−𝟏). 
(ICRP, 2007a) 
Exposed Cancer Heritable effects Total detriments 
population 2007 1990 2007 1990 2007 1990 
Whole 5.5 6.0 0.2 1.3 5.7 7.3 
Adult 4.1 4.8 0.1 0.8 4.2 5.6 
 
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2.3.4.2. Radiation Protection Principle 
The purpose of radiation protection is to control exposure to ionizing radiation in order to 
avoid deterministic effects and ensure that the likelihood of stochastic effects is kept 
below the unacceptable level. To achieve this objective, ICRP (2007a) recommended 
three basic principles of radiological protection which are: justification of the practice, 
optimization of protection and application of dose limitation.  
 Justification of practice: for any procedure that involves ionizing radiation, the 
benefits must be well established and accepted by both medical practitioner and society at 
large. ICRP publication 103 ICRP, (2007a) state as a principle of justification that “any 
decision that involves the radiation exposure situation should do more good than harm” 
and (ICRP, 2007b) in publication 105 said that,  “in the case of the individual patient, 
justification normally involves both the referring medical practitioner who refers the 
patient (example of patients physician/surgeon) and the radiological medical practitioner 
under whose responsibility the examination is conducted”. In fluoroscopy guided 
intervention the responsibility rest with the interventionist. 
 Optimization: find a way to do the examination at a lower dose while 
maintaining efficacy and accuracy. In optimization process the likelihood of incurring 
exposures, the number of people exposed and their individual doses should be kept as 
low as reasonably achievable. It should be considered from the design stage of equipment 
and installation, through operation to decommissioning and waste management.  
 Dose limits: 
Dose limitation is defined in the BSS as “the value of effective dose or equivalent dose to 
individual from controlled practices that shall not be exceeded”. For occupational 
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exposure, it is applied to the sum of effective dose from external sources. Table 2.2 
present the new dose limits for individuals occupationally exposed. 
Table 2.2: ICRP’s recommendations for dose limits (ICRP, 2007; ICRP, 2013) 
 
Effective Dose Limits 
20 mSv per year averaged over 5 years 
50 mSv in a single year 
Equivalent Dose Limits 
Lens of the eye 20 mSv per year averaged over 5 years 
50 mSv in a single year 
Skin 500 mSv per year averaged over 1 cm²  
area of skin regardless of the area exposed 
Extremities  500 mSv per year 
 
2.3.4.3. Dose Constraint 
The use of dose constraint is highly recommended in optimization of protection. For 
occupational exposure, dose constraint is that value of individual dose from a source 
(always lower than annual dose limit) serving as upper bound on the predicted dose in 
optimization of protection for that source. In the case that the boundary is exceeded, 
meaning that protection is not optimized, an investigation should be conducted. For better 
optimization, an investigation level should be established in term of effective dose or 
equivalent dose received monthly. The monthly investigation level will serve as an alert 
to review the level of protection to that period of time and it should not exceed annual 
dose limit or dose constraint when it is extrapolated to a year. 
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In 2000, the World Health Organization (WHO) recommended an investigation to be 
carried out when monthly exposure reaches 0.5 mSv for effective dose, 5 mSv for eye 
lens, or 15 mSv for the extremities (WHO, 2000). With the review of annual eye lens 
dose, Duran et al (2013) proposed for interventional cardiologists a new investigation 
level of 2 mSv per month.  
2.4. Strategies to Reduce Radiation Risk to Staff  
It is the responsibility of all staff members working in radiation to take measures that will 
enhance radiation protection and safety in the department. Techniques used to reduce 
patient dose, will reduce the scatter radiation to operators and thus decrease occupational 
radiation dose. Cardiovascular and Interventional Society of Europe summarized dose 
reduction techniques generally applied in interventional cardiology procedures in table 
2.3 below (Miller et al, 2010). 
 
 
 
 
 
 
 
 
 
 
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Table 2.3: Dose reduction techniques commonly used fluoroscopy procedures 
(Miller et al, 2010) 
Techniques used in interventional cardiology Corresponding functions 
Minimize use of fluoroscopy time and use low Reduce staff and patient dose 
fluoroscopy mode 
Number of fluorographic images Reduce staff and patient dose 
Image-chain geometry Reduce patient dose 
Collimation of the radiation field Decrease the level of scatter dose 
Medical staff position in a low-scatter area Reduce staff dose 
Wear protective shielding Reduce radiation dose to eye lens 
and other organs 
Fluoroscopic imaging equipment comply with Dose-reduction technology is 
International Electrotechnical Commission  incorporated into the imaging 
(IEC, 2010) systems 
Obtain appropriate training provided by Increase awareness of radiation 
professional bodies protection and dose reduction 
Wear personal dosimeter Know and monitor your own 
dose 
Diagnostic reference levels Monitor clinical practice and 
radiation dose 
 
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2.4.1. Practical Application of Optimization of Protection  
The basics tools of occupational radiation protection are time, distance and shielding.  
2.4.1.1. Time  
Fluoroscopy time should be minimized by screening only when necessary. The health 
care personnel should limit the amount of time spent close to the radiation source.  
2.4.1.2. Distance  
The shorter the distance, the higher is the exposure.  The longer the distance, the lesser is 
the exposure. The health care professional should avoid direct beam and keep the 
maximum distance from the patient.  
2.4.1.3. Shielding 
Shielding is the key for staff dose reduction and it is applied at three levels: architectural 
shielding, equipment – mounted shields and personal protective shield (Christopoulos et 
al., 2015). The most important component of personal protective shielding is the lead 
apron which must be worn by all staff present in the fluoroscopy room. The common 
thickness of lead apron used in fluoroscopy room is 0.25 mm on the back and 0.35 mm 
on the front or 0.25 mm on the back and 0.5 mm on the front. Depending on the X – ray 
energy (kV setting) and the lead equivalent thickness of the apron, the lead apron may 
reduce the dose by 85% - 99% (Bushberg et al., 2012). The use of lead glasses is strongly 
recommended to interventional Cardiologists and Radiologists and can reduce the eye 
exposure of the operator by 85% to 90% (Kim et al., 2009). A separated thyroid shield is 
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also recommended for workers in X – ray room. Most catheterization laboratories is 
equipped with a ceiling suspended screens which contain lead impregnated in plastic or 
glass and a table mounted lead curtain which provide effective attenuation. Roguin et al 
(2012) and Reeves et al (2015) reported brain tumor at the left side of the head of 
interventional cardiologists, saying that it was caused by radiation exposure.  
2.4.2. Education and Training Programs 
Training is a basic requirement for healthcare professional in terms of optimization of 
radiation protection. It increases awareness of the risk of radiation and enhance the use of 
protective measures in order to reduce exposure. 
In interventional procedures where, high dose of radiation is used, proper education and 
training is highly recommended for all staff (cardiologists, nurses, technologist, etc.) at 
the time of employment and as part of continuing education program. In 2009, Vano et al 
(ICRP publication 113) included training in radiological protection as part of Quality 
Assurance (QA) program, highlighted its importance and give specific recommendations 
for interventional procedures (Vano et al., 2009). 
Georges et al (2009) provided training materials to improve radiation protection and 
safety in interventional procedures showing the successful impact of training program on 
dose reduction.  
2.5. Individual Monitoring  
Personal monitoring is considered as the gold standard for radiation surveillance in 
intervention procedures (Christopoulos et al., 2015). Personal dosimeters must be 
adequately accurate in different exposure conditions, small and lightweight for the 
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convenience in use such that it will not affect staff performance in exercising their task. 
The individual monitoring of health professional can be achieved using two types of 
dosimeters: passive dosimeters and active dosimeters. 
2.5.1. Passive dosimeters 
They give information on the personal dose after processing. Film, thermo luminescent 
dosimeters (TLDs), optically stimulated luminescent (OSLs) badges are some examples. 
They are small, lightweight, do not require power and well package for the comfort of 
staff. These are the most used in personal dosimetry around the world. The reading 
process makes the dosimetry system suitable to verify compliance and not convenient for 
optimization (ICRP, 2018). 
2.5.2. Active Personal Dosimeters (APDs) 
They are also called electronic dosimeters. They provide instant information of the dose 
when it is exposed to radiation.  It is suitable for optimization and analysis of dose by 
procedure. The direct feedback on the dose give opportunities to staff to take actions 
within a procedure if needed and evaluate the effectiveness of the protective action taken.  
It also facilitates auditing of the wearing of APDs during procedures and the study the 
correlation between occupational and patient exposure (ICRP, 2018). For photon energies 
between 20 and 150 keV and spectra used for fluoroscopy procedures, the dosimetry 
system must meet IEC standard (IEC, 2012) and internationally accepted guidance 
(ICRP, 2010; IAEA, 2014). It must be simple, reliable and efficient to execute required 
action (ICRP, 2018). 
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2.6. Assessment of Occupational Exposure 
2.6.1. Effective Dose Assessment 
The accuracy and precision on the dose assessment depend on the location of the 
dosimeter on the body. In fluoroscopy guided procedures, workers are partly shielded. 
Therefore, single dosimeter placed over the lead apron will overestimate the dose, the 
same way a single dosimeter placed under the lead apron will underestimate the dose 
because it doesn’t consider the unshielded part of the body such as head, hands, legs etc. 
therefore a correction factor should be applied to the reading of the dosimeters for better 
estimation of effective dose (Siiskonen et al., 2007). 
2.6.1.1. Double Dosimetry Approach  
All personnel working in radiation area must be monitored. In interventional procedures, 
ICRP (2000) recommends the use of two dosimeters (one worn on the trunk of the body 
inside the lead apron and another outside the lead apron on the thyroid collar at the left 
side). This has been approved by the National Council on Radiation Protection (NCRP, 
2010) as it provides the best estimation of the effective dose. The algorithm used to 
combine the reading of the two dosimeters is in the form of equation 2.4.      
𝐸 =  𝛼 𝐻𝑈 +  𝛽 𝐻𝑂                                        (2.4) 
Where E is the effective dose, 𝐻𝑈  and 𝐻𝑜  are the personal dose equivalent Hp (10) 
measured under the apron and over the apron on the collar respectively, 𝛼 and 𝛽 are the 
factors to be applied to the dosimeter reading. Over the years many couples of 𝛼 and 𝛽 
has been proposed by many authors, but there is not international agreement on which 
one should be used. Among the entire double dosimetry algorithm tested by Jarvinen et 
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al. (2008) within the European Coordinated Network for Radiation Dosimetry 
(CONRAD), ICRP (2018) found  𝛼 and 𝛽 combination proposed in the Swiss Ordinance 
(2008) to be the best to estimate the effective dose. 
2.6.1.2. Single Dosimetry Approach 
Although the double – dosimetry approach provides better accuracy, it has some 
disadvantages: 
 No international agreement on the algorithm that should be use. This makes the 
comparison of the effective dose difficult to interpret. 
 No reliability in wearing two dosimeters correctly and consistently by the 
interventionists. 
 The higher cost of two dosimeters. 
A single dosimeter worn under the lead apron gives the dose received by radiosensitive 
organs at the trunk. the monthly reading of these dosimeters is often below the detection 
level, making this monitoring technique poor and limited in providing information. Many 
studies have shown that there is no significant difference between double – dosimetry and 
one dosimeter worn over the lead apron corrected by a factor (ICRP, 2018). 
Based on studies of the relationship between Hp (10) from the over apron dosimeter and 
Monte Carlo simulation or direct measurements using an anthropomorphic phantom, 
Martin and Magee (2013) proposed an algorithm of effective dose for staff performing 
fluoroscopy procedures in radiology, cardiology and interventional radiology. The 
algorithm defines in equation 2.5 was accepted and proposed by ICRP publication 139 in 
2018. 
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𝐸 = 0.1 𝐻0                                                                        (2.5) 
2.6.2. Assessment of Equivalent Dose to the Lens of the Eye 
 Before ICRP (2011) new recommendation of eye lens dose limit, the eye lens dosimetry 
was hardly performed by clinicians, who were assuming that the limit was too high (150 
mSv) and that the whole-body monitoring was enough to provide reliable eye lens dose. 
In 1992, ICRU recommended the use of the personal dose equivalent Hp (3) to assess the 
eye lens dose (ICRU, 1992). This operational quantity was found suitable for the eye lens 
dosimetry, but dosimeters calibrated in term of Hp (3) are non-available in many 
countries. ICRP in publications 103 and 117 recommended the use of Hp (0.07) for 
monitoring of the lens of the eye for photon exposures (ICRP, 2007; ICRP, 2010).  IAEA 
(2013) suggested that Hp (0.07) can be used to approximate Hp (3) for photon radiation 
field and Hp (10) can only be considered when the mean energy of the photon spectrum 
reaching the dosimeter is more than 40 keV. IAEA (2014), ISO (2015) and International 
Radiation Protection Association in Paris (IRPA, 2017) have provided the monitoring 
procedure for the lens of eye. Clerinx et al (2008) and Martin (2009) based on Monte 
Carlo study, proposed a factor between the equivalent dose Hp (0.07) read from a 
dosimeter worn at the collar level and eye lens dose. 
Personal monitoring program consist in monitoring, recording, evaluating and reporting 
the radiation dose received by individuals occupationally exposed to radiation in a 
department. All the staff exposed to radiation must be monitored at the international 
standard, especially those performing fluoroscopic procedures.  
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CHAPTER THREE 
3.0. Material and Method 
This chapter will focus on the description of the study area, sample size, materials and 
methods used for data collection and analysis. 
3.1. The Study Area 
This study was conducted in the biggest referral hospital in Ghana. KBTH is situated at 
5° 32′ 16.2″ north, 0° 13′ 38.67″ west, 5.5374 latitude and – 0.2274 longitude, 
Guggisberg Avenue of Ablekuma Sub – locality in Accra Metropolis District, Greater 
Accra Region of Ghana. Figure 3.1 present the location of KBTH in Ghana. 
 
Figure 3.1:  Location of KBTH in Greater Accra Region 
 
Korle Bu means the valley of the Korle lagoon. It was founded on 9th October 1923 as a 
general hospital to address health issues of the population. KBTH leads three centers of 
excellence, the National Cardiothoracic Centre (NCTC), the National Plastic and 
Reconstructive Surgery and the National Centre for Radiotherapy and Nuclear Medicine 
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and has 17 clinical and diagnostic departments/units. Because of sophisticated procedures 
provided in various field, KBTH attract patients from all over Ghana and West Africa 
Sub-region and sometimes from other countries in Africa. 
In KBTH, fluoroscopy guided procedures are conducted in the Radiology Department, 
Accident Department and NCTC. Because of some factors such as the limited time 
allocated for the study, limited number of equipment available and the limited access to 
the departments, this study was focused in the Radiology Department and NCTC. 
3.1.1. Radiology Department of KBTH 
The Radiology Department is well equipped with different modalities system to attend to 
in and out patients. The systems include X-ray machines used for general radiography 
such as chest, pelvis and spine etc., one over couch fluoroscopy unit for special 
diagnostic examination like barium studies, Hysterosalpingogram (HSG), Intravenous 
Urogram (IVU), myelogram sometime for interventional procedure (biliary drainage) 
etc., three ultrasound machine, X-ray machine for emergency cases, one Computed 
Tomography (CT) scanner, Magnetic Resonance Imaging (MRI) scanner and portable X-
ray at surgical department. The department transfers nine (9) Consultant Radiologists and 
18 in training, among whom four (4) are assigned for fluoroscopy examinations on the 
monthly basis. The fluoroscopy room has two trained radiographers and two nurses. 
Fluoroscopy examination room is very spacious 6 m x 6.8 m (40.8 m2). The walls are 
made up of concrete material of about 30 cm width. Console room is separated from 
examination room by wall of 28.5 cm width and 220 cm height and had a glass screen 
lead equivalent. The entrance door to the room is made up lead sheet of 3 mm and had a 
warning light on top of the door which illuminate when the X-ray is on. The room is 
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equipped with two screens (one in the examination room for Radiologists and one in the 
console room for Radiographers) and functional air conditioner 
The fluoroscopy unit is SHIMADZU FLEXAVISION (CE 0197) over couch as shown in 
figure 3.3. It was manufactured in Japan in February 2012. Model: Collimator type R – 
30 H and serial number 3Z0FF7D22045, the maximum tube kVp 150 and Al equivalent 
is 1.0 mm. The unit is powered by one generator model Servo – REG with serial number 
130451, manufactured the 24th April 2013. The standard distance from the source to bed 
is one meter. 
 
Figure 3.2: Over couch fluoroscopy Machine at the Radiology Department, KBTH 
 
3.1.2 National Cardiothoracic Centre (NCTC) 
The NCTC shown in figure 3.3 was founded in January 1989 by Dr. Frimpong – 
Boateng. It is a very dedicated center with a 30 beds ward, 2 operating theatres, a 
laboratory, radiology, echocardiography services, cardiac catheterization laboratory and a 
renal dialysis unit. Staff members comprise a team of seven cardiothoracic surgeons 
assisted by Cardiologists, Anesthetists, cardiovascular Perfusionists, nurses, 
Technologists etc. 
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NCTC offer their services to patients from all over the country and receives regular 
referrals from Nigeria, Sierra Leone, Gambia, Liberia, Togo etc. (Edwin et al, 2011). 
 
Figure 3.3: Outlook of the actual NCTC at KBTH 
 
Cardiac Catheterization Laboratory (Cathlab) is used in modern cardiology and cardiac 
surgery for diagnostic and treatment of many heart diseases without opening the heart of 
the patient. The new cathlab was installed in October 2016 and inaugurated on 
Wednesday 4th January 2017 by the former Ghana President John Mahama. The 
fluoroscopy unit at the cathlab in figure 3.4 is the type Siemens (Artis Zee/Zeego)  
Megalix catplus 125/40/90 – 121 GW, model  N° 10144181 and serial number  
640041673. The maximum tube voltage is 125 kV – IEC 60613 and total filtration is 0.8 
mm Al/80 kV. It was manufactured in February 2016 in Germany.  
Examination room 
Console room 
 
Figure 3.4: Internal view of Cathlab with Siemens biplane fluoroscopy unit. 
 
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3.2. Sample Size 
All operators who conducted fluoroscopically guided procedure during the period of data 
collection in Radiology Department and NCTC were the sample size of this study. A total 
of four (4) Radiologists and four (4) Cardiologists were monitored.  
3.3. Materials 
A questionnaire was been issued to assess the level of radiation protection practices in the 
cathlab. The Pirhana was used for Quality Control (QC) on equipment, KAP meter was 
used to record patient dose for fluoroscopy procedures conducted in radiology 
department, electronic dosimeters for personal monitoring, survey meter for area 
monitoring.  
3.3.1. Questionnaire 
A set of questions were prepared for the purpose of interview. Based on these questions, 
an interview was done between the investigator and the chief nurse (who is in charge of 
the cathlab), Cardiologists and Radiologists. This was done in order to collect 
information on radiation protection and safety measures practice in the laboratory to 
prevent the risk of ionizing radiation both for patient and workers. The questions had two 
main parts: the first part was about the general information on the equipment and the 
second focused on the information regarding the radiation protection of the personnel. 
3.3.2. Piranha 
 Pirhana is a Radiation to Information (RTI) package used for an instant X – ray Quality 
Assurance (QA) solution. It is an all in one multimeter that can be connected to a 
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computer wireless or via Universal Serial Bus (USB). It works with the diagnostic RTI 
software ocean 2014, which is used to display, record and report all the measurements, 
waveforms and facilitate the reading on a screen. The Piranha was used in this work for 
the quality control test of the fluoroscopy units at Radiology Department and NCTC. The 
Piranha version 5.5 with serial number CB2 – 15020088, was manufactured in Sweden 
and calibrated the 11th March 2015 by SWEDAC. ACKREDICTERING. The Piranha 
was connected to a computer with an Ocean 2014 software installed on the window 7 
systems for reading (Figure 3.5). Table 3.1 presents the specifications of the piranha 
used. 
 
 
 
Figure 3.5: Setup of QC tools (piranha and ocean 2014 installed on a computer) 
under the X – ray system 
 
 
 
 
 
 
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Table 3. 1: Specifications of the Piranha for radiography / fluoroscopy 
 
Elements                          Specifications 
 
Dose                                 Range: 0.1 nGy–1500 Gy*, Inaccuracy:  5% 
Dose Rate                        Range: 1 nGy/s*–320 mGy/s, Resolution: 0.2 nGy/s*, 
 Inaccuracy: 5% or 0.25 nGy/s 
Total Filtration              60–120 kVp, 1–90 mm Al or 2 mm Cu  
.  
kVp Range: 35–160 kVp, Minimum Dose Rate: 0.1 µGy/s,  
 Inaccuracy: 1.5% 
HVL Range: 0.72–13 mm Al, Minimum Peak Dose Rate: 0.1  
 µGy/s, Inaccuracy: 10% or 0.2 mm Al. 
 Quick HVL in one exposure  
Total filtration               Range: 1.0–90 mm Al, Minimum Dose Rate: 0.1 µGy/s  
                                         Inaccuracy: 10% or 0.3 mm Al 
Time                                Range: 0.1 ms–2000s, Resolution: 0.5 ms,   
 
                                         Inaccuracy: 1% or 0.5 ms 
 
 
3.3.3. Kerma Area Product Meter 
The Kerma X – plus is made of a transparent ion chamber, model 120 – 131 and serial 
number 01A04042 (50 – 150 kVp, Class II – type B), with a separated reader with “10 – 
digit LCD “Single Line Display”, model 120 – 210 with serial number o1E004774. It was 
manufactured by IBA dosimetry service. The ion chamber was fixed on the collimator of 
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the X – ray unit at the radiology department to measure DAP for patient dose monitoring. 
Figure 3.6 below shows the Kerma X – plus package used for this study. 
(a)     (b) 
Figure 3.6: (a) The Kerma X – plus with the separated reader and (b) the ion 
chamber fixed on the X – ray tube in radiology department. 
3.3.4. Electronic Personal Dosimeter (EPD) 
Four (4) labeled EPD of type EPD MK 2.3 manufactured by Thermo Electron 
Corporation were used for this study to measure the dose to the personnel. The 
corresponding serial numbers of the EPDs were 00179975, 00178174, 00070491, 
00179958. The EPD is a direct reading dosimeter suitable to use in occupational 
dosimetry according to the Radiation Protection and X – ray ordinance 
(FO75KOM06A/Datasheet EPD MK, 2014). Personal dosimeters is used to measure 
personal depth dose equivalent Hp (10) and the personal surface dose equivalent Hp 
(0.07) both from photons (X-rays and gamma radiation) and beta radiation. It can be 
attached to the clothing with a clip mounted on the housing well display in figure 3.7 
below. 
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Figure 3.7: Electronic Personal Dosimeters used for this study 
 
These dosimeters were calibrated at the Secondary Standard Dosimetry Laboratory 
(SSDL) of GAEC to check the accuracy on the reading during the study. The Calibration 
set up is shown in figure 3.8 below. 
Cesium source 
EPD 
 
Figure 3.8: Calibration setup in SSDL at GAEC 
 
3.3.4.1. Measurement Method 
The radiation detector is made of PIN diodes in which charges are induced by radiation 
(electron – hole –pairs). The measurements of charges in terms of electric current 
constitute the measurement of the dose rate from which the value of the dose can be 
derived by adding the time (is stored in the dosimeter and can be read out via an infrared 
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interface). The thin beta - window is used to measure beta radiation because of its low 
penetrating power. The detailed picture of the EPD used for this study is shown in figure 
3.9 below. 
 
 
Figure 3.9: Typical personal dosimeter (Source: www.helmholtz-muenchen.de/awst) 
3.3.4.2. EPD MK 2+ Radiological and Environmental Specifications 
The Thermo Scientific Mk2+ EPD is perfect for organizations, utilities, agencies, and 
research laboratories to monitor employee dose and dose rates. The radiological and 
environmental key features of these instruments as stipulated in the user manual are 
presented in tables 3.2 and table 3.3 respectively.  
 
 
 
 
 
 
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Table 3.2: EPD MK 2+ Radiological Specifications 
Components Details 
Display Units Sv and rem  OR scaled in Sv and cGy (with prefixes) 
Dose Display and Storage 0 μSv to > 16 Sv (0 mrem to > 1600 rem) 
Display Resolution 1 μSv (0.1 mrem), up to 10 Sv 
Storage Resolution 1/64 μSv (=1.5 μrem) 
Photon: Hp(10): [All ref. 137Cs]: ±50% 15 keV to 17 
keV; ±20% 17 keV to 1.5 MeV; ±30% 1.5 MeV to 6 
MeV; ±50% 6 MeV to 10 MeV 
Energy Response Photon: Hp(0.07): [All ref. 137Cs]: ±30% 20 keV to 6 
MeV; ±50% 6 MeV to 10 MeV 
Beta: Hp(0.07): ±30% 250 keV to 1.5 MeV (ref. 
90Sr/90Y) 
Angular Response Hp(10) 137Cs ±20% up to ±75º; Hp(10) 241Am ±50% 
up to ±75º; Hp(0.07) 90Sr/90Y ±30% up to 55º 
Accuracy Hp(10) 137Cs ±10%; Hp(0.07) 90Sr/90Y ±20% 
Hp (10) 137Cs: ±10% <0.5 Sv/h (<50 rem/h); ±20% 0.5 
to 1 Sv/h (50 to 100 rem/h); ±30% 1 to 2 Sv/h (100 to 
200 rem/h); ±50% 2 to 4 Sv/h (200 to 400 rem/h); 
 
Between 4 and 50 Sv/h continues to accumulate dose at 
Dose Rate Linearity a rate > 1 Sv/h 
Hp (0.07) 90Sr/90Y: ±20% <1 Sv/h (<100 rem/h); 
Between 1 Sv/h and 50 Sv/h continues to accumulate 
dose at a rate > 1Sv/h 
 
 
 
 
 
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Table 3.3:  EPD MK 2+ Environmental Specifications 
 
Components Details 
Operating Temperature 
-10ºC to +50ºC (+14ºF to +122ºF) 
 
Humidity 
20% to 90% RH, non-condensing 
 
Vibration 
IEC 1283: 2g, 15 minutes, 10 to 33 Hz 
 
 
3.3.5. Dose Rate Meter 
The dose rate meter presented in figure 3.10 is the type PM1703MO – 2. It is a personal 
combined radiation detector/dosimeter manufactured by Polymaster with serial number 
2160498.  
 
 
 
       
 
 
 
Figure 3.10: Dose rate meter used in this study 
 
This instrument is designed to measure ambient Dose Equivalent Rate (DER) 𝐻∗(10) of 
gamma and X – ray radiation, to detect and locate radioactive materials and alerting the 
user with audible, visual and vibration alarms.  
Figure 3.11 and table 3.4 show the design and characteristics of the dose rate meter 
respectively according to the operational manual. 
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Figure 3.11: Functional parts of the dose rate meter (Source: www.Polimaster.com) 
 
Table 3.4: Characteristics of the dose rate meter  
Specifications PM 1703MO – 2 
Detector  
- gamma search CsI(Tl) 
- gamma measurement GM tube 
Sensitivity  
- for 137Сs , ± 20 % 85 (s-1)/( Sv/h) (1.0 (s-1)/( R/h)) 
- for 241Am , no less 130 (s-1)/(μSv/h) (1.3 (s-1)/(μR/h)) 
Energy range 0.033 - 3.0 MeV 
Time of measurement 0.25 s 
Dose Rate 0.01 Sv/h - 10 mSv/h (1 R/h - 1000 mR/h) 
Maximum permissible intrinsic ±30% in measurement range 
relative error of DER measurement in 0.1 μSv/h - 10 Sv/h (10 μR/h - 1000 R/h) 
measurement range 
Alarm type visual, audio, vibration 
Operating temperature -30°C to 50°C (-22°F to 122°F) 
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3.4. Software 
3.4.1. Microsoft Excell 
The software used for the data analysis in this study was Microsoft excel 2010 version 
14.0 included in Microsoft office 2010 installed on a window 7 system. 
Excel provides functions to solve statistical, engineer and financial problems and it is 
used to display data as line graphs, histograms and charts. It supplies pivot tables and 
scenario manager that can be used to section data in order to view dependencies between 
variables (Greg, 2007). It can also be used for numerical methods to solve differential 
equations in mathematics and physics. Figure 3.12 shows the interface of excel 2010 
running on window 7. 
 
Figure 3.12: Microsoft excell 2010 running on window 7 
 
3.4.2. Simple Geo 
Simple Geo version 4.3.3 was used in this work. It is an interactive solid modeler used to 
implement geometries for particles transport problems. It provides a flexible and easy 
platform to create modes via drag and drop, and also debugging facilities based on 
stochastic and deterministic methods for validation of the created geometry. In other 
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word Simple Geo offers an interface where the created geometry is visualized so that 
corrections and modifications can be immediately done. The created geometry in Simple 
Geo can be exported to ray tracing packages such as FLUKA, Monte Carlo N particle 
(MCNP), etc. (Theis et al., 2006). The following figure 3.13 presents a geometry creates 
with Simple Geo. 
 
Figure 3.13: Simple Geo interface with an example of geometry created (Theis et al., 
2006). 
3.4.3. Monte Carlo N Particle (MCNP) 
 MCNP is a general purpose, continuous energy, generalized – geometry and time 
dependent code developed by Los Alamos National Laboratory (LANL). It is designed to 
simulate fission and particle interaction (neutron, photon, electron or coupled neutron / 
electron / photon) over a broad range of energies. It found its application in many areas 
such as radiation shielding, medical physics, dosimetry and radiation protection, nuclear 
reactor modeling, etc. it is a three-dimensional geometry with flexible source and tally 
options, interactive graphics, and support for both sequential and multi – processing 
computer platforms. The latest version is MCNP 6 package which gives abilities to 
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import unstructured mesh geometries from the finite element code, to model complete 
atomic relaxation emissions, etc. 
3.5. Methods 
Approval letter to conduct this research were provided by the College of Basic and 
Applied Science and also the KBTH Scientific and Technical Committee (KBTH-STC). 
The ethical clearance was obtained from the Institutional Review Board (IRB) of KBTH. 
3.5.1. Quality Control (QC) Tests 
In order to verify that the fluoroscopy equipment was performing consistently, standard 
QC tests were undertaken before all measurements. The following are the parameters 
which were checked: beam collimation, kVp accuracy and reproducibility, time 
reproducibility, half value layer, leakage test, mAs linearity and exposure reproducibility 
and compared with the standard limits provided by Nuclear Regulatory Authority of 
Ghana (NRA, 2016). The room size has been measured using the tape meter. The 
distance between the X –ray source and the table were 1 m.  
3.5.1.1. Beam Collimation 
This test is performed to check if the X – ray beam coincides with the light field, because 
the radiation field may be shifted away from the area of clinical interest. This was 
achieved by placing a sheet of paper under the radiation field and height (8) coins of 20 
pesewas were positioned strategically on the corners (in and out) of the sheet of paper 
and some images were taken. The accuracy on the collimation was checked by measuring 
the distance of the shifting of coins on the image using the meter provided at the 
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computer screen. Figure 3.14 shows one image of the collimation check. The distance 
measured was subtracted from the diameter of the coin (23 mm).  
 
Figure 3.14: Radiograph from the beam collimation check 
 
3.5.1.2. Reproducibility Test 
For every X – ray machine, some parameters such as kV, exposure time and exposure 
should be reproducible. To assess the reproducibility, the machine was set at 80 kV and 
10 mAs. The exposure was repeated three (3) times and the results were registered in the 
Ocean 2014 software. For all these parameters, the coefficient of variation should be less 
than 5% and this was calculated as follows (NRA, 2016): 
Standard deviation
Coeficient of Variation (COV) =   × 100%           (3.1) 
Average
3.5.1.3. kVp and Exposure Time Accuracy 
For kV, the test was performed at tube voltage 70 kV up to 115 kV at the highest tube 
current (250 mA and 110 ms). The readings were registered and the percentage of error 
was automatically calculated by Ocean 2014 according to equation (3.2) (find the results 
on Appendix 5). 
(V − V )
Percentage kVp error =  0 S  × 100                                      (3.2) 
VS
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Where V0 is the measured value and VS is the set value. The percentage kVp error should 
lie within ±6% (NRA, 2016). 
The machine was set at 80 kVp, 250 mA and  the first time at 8 ms. The procedure was 
repeated for different time 63 ms, 100 ms, and 0.125 s. The percentage error should lie 
within  ±10 % (NRA, 2016).  It has been calculated according to equation (3.3) below. 
(T − T
Percentage timer error =  0 S  × 100                                      (3.3) 
TS
Where T0 is the measured value and TS is the set value. 
3.5.1.4. mAs Linearity 
To perform this test, the parameters of the machine were set at 80 kV and at first 2.5 
mAs. The exposure, time kV was recorded and the value of exposure / tube current (mGy 
/ mAs) was calculated. This procedure was repeated for 20 mAs, 32 mAs, and 40 mAs. 
The maximum and minimum values of (mGy / mAs) were recorded and the linearity was 
found according to equation (3.4). It should be less than 10% (NRA, 2016). 
𝑀𝑎𝑥−𝑚𝑖𝑛
 ≤ 10%                                                                                 (3.4)         
𝑀𝑎𝑥+𝑚𝑖𝑛
3.5.1.5. Half Value Layer (HVL) 
The determination of HVL was obtained directly from the Piranha at one exposure when 
the setting of the machine was 80 kVp and 250 mA, and 0.11 s. this value should be more 
than 2.3 mm Al (NRA, 2016). 
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3.5.1.6. Leakage Test 
The tube output rate free in air was measured using the dose rate meter (survey meter) at 
one-meter distance from focal spot to front, back, right and left of the X – ray tube when 
the collimator is completely shut at maximum kVp (125 kVp) and 25 mAS. The values 
should be less than 1 mGy/h. 
3.5.2. Dose Monitoring  
The four dosimeters used for measurements were labeled (chest 1, chest 2, neck 1, and 
neck 2) in order to reduce errors during the readings.  All measurements were performed 
within one month at Radiology Department and two months at the Cathlab. For every 
type of procedures requiring the presence of the operator near the patient, dose to the 
workers were measured. Two electronic dosimeters (thermo fisher) were issued for every 
operator conducting the procedure. One dosimeter was fixed under the lead apron at chest 
level and the second one, over the lead apron on the thyroid shield at neck level. For 
patient dose, the KAP meter was fixed on the X-ray tube (Radiology). The following 
parameters were recorded in both departments: 
- The type and the number of the procedure performed by each operator. 
- The patient dose (DAP) per procedure. 
- The screening time of each procedure. 
- The personal equivalent dose Hp (10) from each dosimeter was recorded daily and 
Hp (0.07) for the dosimeter worn over the lead apron at neck level. 
- The protective equipment available in the room and the protective actions. 
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3.5.3. Scatter Radiation Study in the Examination Room 
Cathlab was modeled according to the measured parameters using Simple Geo.  
Height 290 cm, length 740 cm, breadth 400 cm and size of the lead glass 100 cm x 315 
cm are presented in figure 3.15. 
 
740 cm 
 
 
 370 
 
S ource 
 
Lead glass 
 
 
Contro l panel 
 
 
 
Figure 3. 15: CathLab dimensions 
 
Scattered radiation dose was measured by irradiating an improvised plastic rectangular 
shape container with rounded corners filled with water used as phantom to simulate a 
standard patient (50 Cm length, 30 cm width and 22 cm height). This is a good 
representative of human trunk. Dose rate was measured at 160 Cm height from the floor 
at each strategic angles (0°, 90°, 180°, 270°) as illustrated in figure 3.16 at 1m from the 
isocenter. The projection angles of the tube at which the data were collected were Left 
Anterior Oblique (LAO) 30°, Right Anterior Oblique (RAO) 30° and Antero Posterior 
(AP) 0° presented in figure 3.17. At each point three measurements were taken and the 
average was calculated in order to reduce errors.  
 
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200 
cm 
400 
cm 
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 160 
I
 100 
Phanto
 Patient bed 
C-
arm 
 
Tub
 
e 
Focal spot 
 
 
Figure 3.16:  Schematic of the side view of measurement set - up 
 
LAO 30° RAO 30 
 AP 
0° 
 
 
 
 
 
Figure 3.17: Schematic of the top view of the measurement set-up showing the point 
of measurements at different angles at 1m from the isocenter. 
3.5.4. Data Analysis 
Microsoft excel was used to analyze data and presented them in tables and graphs. The 
correlation between the KAP values recorded and staff dose was done by regression 
analysis to determine the P-value, R² and the possible equation which can be used for 
prediction. 
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3.5.4.1. Whole – Body Dose Calculation 
In agreement with regulatory requirement, staff dose monitoring is mostly done by the 
use of one dosimeter worn at chest/waist level under the lead apron and the recorded 
value from the dosimeter represents the effective dose (ICRP, 2000). The methodology 
for personal monitoring used in this study is the double dosimetry (one dosimeter worn in 
lead at waist level and another out lead at neck level on the thyroid collar) method 
recommended by NCRP (1995) and ICRP (2000) for both Radiologists and Cardiologists. 
Many algorithms have been developed combining dose recorded from the two 
dosimeters, but there is no yet an international consensus about which algorithm to use. 
The table 3.5 presents some algorithm proposed by different authors for effective dose 
calculation both for single dosimeter and double dosimeters. 
Table 3.5:  Algorithm proposed for effective dose calculation with thyroid collar 
[adapted from Jarvinen et al. (2008) and ICRP publication 139 (2018)] 
Source Dosimetry Effective dose estimation 
Type 
NCRP Report 122 Single 𝟏
𝑯𝒑(𝟏𝟎) 𝑶𝒗𝒆𝒓  ×   𝟐𝟏
(NCRP, 1995) 
Martin and Magee (2013) Single 𝟎. 𝟏 × 𝑯𝒑(𝟏𝟎)𝑶𝒗𝒆𝒓  * 
NCRP Report 122 Double 𝟎. 𝟓𝑯𝒑(𝟏𝟎)𝑼𝒏𝒅𝒆𝒓 + 𝟎. 𝟎𝟐𝟓𝑯𝒑(𝟏𝟎)𝑶𝒗𝒆𝒓 
(NCRP, 1995) 
Swiss Ordinance (2008) Double    𝑯𝒑(𝟏𝟎) 𝑼𝒏𝒅𝒆𝒓 +  𝟎. 𝟎𝟓 𝑯𝒑(𝟏𝟎)𝑶𝒗𝒆𝒓 * 
Clerinx et al, 2008 Double 𝟏. 𝟔𝟒𝑯𝒑(𝟏𝟎) 𝑼𝒏𝒅𝒆𝒓 + 𝟎. 𝟎𝟕𝟓𝑯𝒑(𝟏𝟎)𝑶𝒗𝒆𝒓 
Chida et al, 2013 Double 0.89 𝑯𝒑(𝟏𝟎)𝑼𝒏𝒅𝒆𝒓 +  𝟎. 𝟎𝟕𝟓𝑯𝒑(𝟏𝟎)𝑶𝒗𝒆𝒓 
 
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(*) represent the algorithms used in this work which was recommended in publication 
139 (ICRP, 2018) for single and double dosimetry using the protective collar. 
𝐻𝑝(10) 𝑈𝑛𝑑𝑒𝑟 is the deep dose calculated from the dosimeter worn at waist level under 
the lead apron and 𝐻𝑝(10) 𝑜𝑣𝑒𝑟 is the dose calculated from the dosimeter worn at neck 
level above the apron. The value of equivalent dose used in this calculation was obtained 
by the following equation 3.5. 
 
𝐻𝑝(10) 𝑟𝑒𝑎𝑙 = k * 𝐻𝑝(10) 𝑟𝑒𝑎𝑑                      (3.5) 
Where k is the calibration factor, 𝐻𝑝(10) 𝑟𝑒𝑎𝑑 is the value read from dosimeters.  
The same equation was applied for 𝐻𝑝(0.07)  
3.5.4.2. Eye Lens Dose Calculation 
The international recommendation of the eye lens monitoring is the use of personal 
dosimeters calibrated in terms of  𝐻𝑝(3). Because of the non – availability of such 
dosimeters, many authors established the correlation between  𝐻𝑝(0.07) read on the 
dosimeter worn on the thyroid collar and the eye lens dose. Some coefficients found in 
literature are presented in the following table 3.6. 
 
 
 
 
 
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Table 3.6: Ratio (eye lens / Thyroid) doses [adapted from Carinou et al. (2015)] 
 
References Ratio (eye lens/Thyroid) Geometry Equipment 
Covens et al (2007) 0.73 
Lie et al (2008) 0.75 * 
under couch tube 
Clerinx et al (2008) 0.75 * 
Hausler et al (2009) 0.68 
Buls et al (2002) 1.22 
Over couch tube 
Sulieman et al  (2008) 1.46 * 
 
(*) are the equations used for eye lens dose estimation for both Radiologists and 
Cardiologists depending on the geometry of the equipment used in this work.            
Monthly dose received by each worker monitored was calculated by summing the daily 
dose over the whole month using equation (3.6). 
𝐸 𝑛𝑀  =  ∑𝑖 =1 𝐸𝑖                                                  (3.6) 
Where 𝐸𝑀 is the monthly dose,  𝐸𝑖is dose received per procedure. 
For cardiologists the annual dose was estimated by calculating the mean of three-monthly 
dose and multiply by twelve (12). 
∑3 𝐸
𝐴𝑛𝑛𝑢𝑎𝑙 𝑒𝑓𝑓𝑒𝑐𝑡𝑖𝑣𝑒 𝑑𝑜𝑠𝑒 =  𝑖=1 𝑀𝑖  × 12                                                (3.7) 
3
3.5.4.2. Workload 
The workload is defined differently depending on whether it is for a device or an 
individual. For a device, it is the weekly radiation output expressed in mA-minute per 
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week. It can also be defined in term of working time or amount of work that is expected 
or assigned to an individual for a period of time. This gives an idea of the time a worker 
spends under radiation whether weekly, monthly or annually. It can also be expressed in 
term of number of procedures. In this study, the workload has been calculated in term of 
total time spent under the radiation and also the number of procedures performed by each 
Cardiologist over a period of 2 months in cathlab. The monthly average workload was 
calculated in order to estimate the annual workload for each worker.  
3.5.4.3. Risk Assessment 
The risk assessment was calculated using the risk coefficient values provided by ICRP 
2007 recommendations given in table 2.1 in the previous chapter. The cancer, heritable 
effect, total detriment and lifetime risk have been estimated for each Cardiologist 
working with radiation. 
The general equation used for cancer and heritable effect risk is expressed as follow in 
equation 3.8: 
Annual Risk (AR)= Eannual (Sv) X Nominal Risk Coefficient              (3.8) 
Where E is the annual effective dose in Sievert (Sv) and the nominal risk coefficient in 
Sv-1 
The total detrimental effect can be estimated by summing the annual cancer risk and 
annual heritable effect risk. 
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3.5.5. Monte Carlo Simulation 
The dimensions of the examination room were taken using tape measure. The location of 
the couch, X-ray tube with respect to the room was located. Dose rate measurement at a 
distance of 100 cm from the couch to the focal spot of the tube was measured using a 
survey meter for verification of the computational model.  
Simple Geo was used to model the X-ray room, phantom and the X-ray source using the 
already taken dimensions. The model was out put into Monte Carlo input file for 
simulation as shown in Appendix 7. The model was verified for accuracy using the 
measured dose rate in air at 100 cm. An X-ray spectrum was generated for the simulation 
at 100 kVp, 12 degree tungsten anode and 2.5 mm Al using SpekCalc (spectrum 
generation software). 
The Monte Carlo input file was simulated on a computer with a processing speed of 3 
GHz. 1.9 x 109 photon particles were tracked for a reasonable computational time and 
output accuracy. Photon dose rate deposited per particle mesh in the X-ray room was 
tallied for the output results. 
The output of radiation dose rate/particle in the room was plotted in a contour to illustrate 
the spread of radiation using GNUPlot (plotting software version 5.2, patchlevel 4). 
 
 
 
 
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CHAPTER FOUR 
4.0. Results and Discussions 
This chapter presents the QC results of the equipment and the compliance with the 
regulatory standard in Ghana. It also presents the overall research finding from the 
assessment done and comparison of workers parameters between the two departments, 
two X-ray tube geometry. The finding was also compared with other studies and 
recommendations of ICRP, IAEA and NCRP. 
4.1. Basic Elements of Radiation Protection in Both Department 
At the Radiology Department among the six (6) staff members working in fluoroscopy 
room, four (4) responded to the questions (one radiographer and three radiologists) and in 
cathlab, the chief nurse, the chief cardiologist and three other cardiologists were the 
respondents. Table 4.1 presents the summarized results of the interview made showing 
the actual state of radiation protection in both departments. 
 
 
 
 
 
 
 
 
 
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Table 4.1: Status of radiation protection measure in both departments 
 
Protective measures  Radiology Cardiology 
In 
Tube Geometry Over couch Under couch 
Presence of warning light Yes Yes 
Lead apron Yes (100%) Yes (100%) 
Thyroid shield (0.35 mm) Yes (100%) Yes (100%) 
Lead glasses   Yes (25%) No 
Lead gloves No  No 
Other protective equipment Not available Yes (full use) 
(ceiling suspended screen and lead 
drap)  
Use of collimation No  No 
Medical physicist  Yes  No 
Refresher training of workers No No 
Quality assurance program No No 
Radiation Protection Officer No No 
Regular QC on the machine No  No 
radiology department, no personnel had received refresher training on radiation 
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protection. They have acknowledged the presence of a Medical Physicists. Survey on 
radiation protective clothing showed the availability of six (6) lead aprons: two (2) one 
side aprons (0.35 mm), two wraps around apron (0.35 mm front and 0.25 mm back), two 
(2) one side aprons (0.5 mm), and one skirt and one shirt (0.35 mm front and 0.25 mm 
back). Other available protective clothing includes three (3) thyroid collar of 0.5 mm, two 
(2) pairs of lead glasses and one pair of lead gloves are for Radiologists. The ceiling 
suspended screen and lead drape were not available. Radiologists expressed the 
inconvenience in using lead gloves due to the small size of catheter and syringes used 
during procedures even though their hands are most often exposed to the direct beam. 
The radiation protection measures to reduce patients and operator doses such as (use of 
collimation, reduce number of images and frame, etc.) were not applied. The record 
keeping in Radiology Department needs more attention. 
At the NCTC, Cardiologists and Nurses affirmed that they have received training on 
radiation protection during their general training, but they have not received any refresher 
training in course of their work. This may be due to the absence of a Radiation Protection 
Officer (RPO) or Medical Physicist, Quality Assurance program in the department. 
Therefore, no frequent QC test is performed on the equipment. In term of personal 
protection equipment, the department is well equipped with one lead curtain (0.5 mm) 
fixed on patient bed, the ceiling suspended screen lead equivalent (0.5 mm), eight (8) 
thyroid collar of 0.5 mm and a total of ten (10) lead apron: four (4) one side apron of 0.5 
mm use by nurses, four (4) wrap around apron of 0.5 mm front and 0.25 mm back, one 
side apron of 0.35 mm and one wrap around skirt and shirt of 0.5 mm front and 0.25 mm 
back. But no lead glasses or gloves were available. Every worker has a well labeled TLD 
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badge provided by Lumina Dosimetry Services. They wear inside the lead apron at waist 
level. But these TLDs had never been read since the starting of the new cathlab in 
October 2017 till the end of this study. Thus, there was not personal dose record in the 
department. Patient’s information and doses details are well recorded and well kept on 
digital form (computer, CDs and external hard disk) and also hard copies.  
In general, table 4.1 reveals the critical aspects of radiation safety program are not 
practiced in both departments. These departments require the presence of a radiation 
protection officer to assure continuous training of workers on radiation protection. The 
QC and radiation survey around the workplace are performed by the regulatory authority 
during their inspection. This study has been useful both for workers and at the 
departmental level in the way that it has brought awareness of radiation exposure to the 
workers. This leads to some practice of protective measures at worker level and will 
contribute to the implementation of continuous personal monitoring in both departments. 
4.2. Quality control results 
4.2.1. Over couch Fluoroscopy in Radiology Department 
Peak tube voltage, screening time and tube outputs measured when set tube voltage and 
mAs are 80 kV and 2.5 mAs respectively are shown in table 4.1 with the calculated 
deviations.  
 
 
 
 
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Table 4.2: kVp, time and output reproducibility test. 
 
Measuring quantities 80 kV, 2.5 mAs Mean COV%  
Actual kV  75.21 75.79 75.62 75.54 0.30 
Time (ms) 31.60 31.61 31.61 31.60 0.03 
Output (µGy) 363.40 363.70 365.30 364.13 0.20 
Peak tube voltage sets and measured together with calculated deviations used to assess 
accuracy are shown in table 4.3.  
Table 4.3: Tube voltage accuracy 
kV accuracy 
Set kV 70 80 90 100 110 115 
Actual kV 69.19 77.9 87.25 97.46 106.89 111.55 
D kV 0.81 2.1 2.75 2.54 3.11 3.45 
% DkV 1.16 2.63 3.06 2.54 2.83 3 
 
For tube voltage set at 80 kV, the set values of mAs, measured values of exposure and 
calculated values of exposure / mAs are presented in table 4.4. 
Table 4.4: mAs linearity 
mAs linearity  (80 kV) 
m A s 2.5 20 32 40 
Exposure (mGy) 0.1085 0.8409 1.307 1.652 
mGy / m A s 0.0434 0.042045 0.04084375 0.0413 
 
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From the values calculated in table 4.4, the mAs linearity is calculated as indicated in 
equation 4.1: 
𝑀𝑎𝑥−𝑚𝑖𝑛 0.0434−0.04084375
The mAs linearity =  =  = 0.03   (4.1) 
𝑀𝑎𝑥+𝑚𝑖𝑛 0.0434+0.04084375
 
A total of seven (7) QC tests were performed on the over couch fluoroscopy tube used at 
the Radiology Department. The calculated deviations for each test and the standard 
acceptable deviations provided by Ghana Nuclear Regulatory Authority are presented in 
the following table 4.5. 
The room size of 40.8 m² is far greater than the minimum required. The beam collimation 
deviation was found between 5 – 6.10 mm which was below the acceptable deviation of 
10 mm. The tube voltage accuracy (3.10 %), mAs linearity (0.03) are both below the 
tolerance ±6%  and 0.1 respectively. The reproducibility of tube voltage, time and 
exposure were 0.3%, 0.03%, and 0.2% respectively. These are less than the tolerance 
±5%. The HVL measured at 80 kV was 3.17 mm Al which is greater than the minimum 
(2.3 mmAl) recommended and the leakage was not detectable by the measuring 
instrument meaning that is was less than 1.00 mGy /h. 
 
 
 
 
 
 
 
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Table 4.5: Summary of the results  
 Deviation of Acceptable  
Parameter Fluoroscopy Deviation    Remarks 
Machine (NRA, 2016)  
(Measurement) 
Room Size (Sq. metre) 40.8 m2  ≥ 25.0 m2 Pass 
kVp Accuracy 3.10 %  ≤ ±6.0 % Pass 
mAs Linearity 0.03  ≤ 0.10 Pass 
Collimation Accuracy 6.10 mm  ≤ 10.0 mm Pass 
HVL (mm Al ) @ 80kV 3.17 mm Al  ≥ 2.3 mm Al Pass 
Tube Leakage at 1m  -  < 1.00 mGy/h - 
Tube Voltage 
Reproducibility @ 0.30 % COV ≤ 5.0 % Pass 
(10mAs,80 kV) 
Exposure Reproducibility  
0.2. % COV ≤ 5.0 % Pass 
@ (10 mAs,80 kV) 
Exposure Time 
Reproducibility @  0.03 % COV ≤ 5.0 % Pass 
(10 mAs,80 kV) 
 
(-) means that, radiation no detectable. 
4.2.2. Under couch Fluoroscopy in Cathlab 
The measured tube voltage, time, output and the calculated deviations are presented in 
table 4.6 below. 
 
 
 
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Table 4.6: Voltage, time and output reproducibility test 
Measuring quantities Values  Mean COV(%) 
Actual kV 77.38 77.55 77.38 77.49 77.45 0.10% 
Time (ms) 270.00 270.00 270.50 270.50 270.25 0.10% 
Output (µGy) 467.20 464.70 469.60 469.60 467.77 0.43% 
 
The console reading, measured tube voltage and the deviation are given on table 4.7 
below. 
Table 4.7: Tube voltage accuracy 
kVp accuracy 
Console kV 77.30 78.70 81.00 81.00 93.80 94.40 
Actual kV 77.77 75.79 80.54 84.10 98.57 100.10 
D kV -0.47 2.91 0.46 -3.10 -4.77 -5.70 
% DkV -0.61 3.69 0.57 -3.83 -5.09 -6.04 
 
A summary of five (5) QC tests was performed on the under couch (C-arm) used in 
cathlab. The measured room size, the calculated deviations and the standard acceptable 
deviations by Ghana Nuclear Regulatory Authority are presented in the following table 
4.8 (NRA, 2016). 
 
 
 
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Table 4.8: Summary of the results of QC test 
 
 Deviation of Acceptable  
Parameters X-ray Machine Deviation    Remarks 
(Measurement) (NRA, 2016)  
Room Size (Sq. metre) 29.30 m2 ≥ 25.0 m2 Pass 
kVp Accuracy 6.04 % ≤ ±6.0 % acceptable 
HVL (mm Al )  3.64 mm Al ≥ 2.3 mm Al Pass 
Tube Leakage at 1m  No detectable < 1.00 mGy pass 
Tube Voltage 0.10 % COV ≤ 5.0 % Pass 
Reproducibility  
Exposure Reproducibility  0.10 % COV ≤ 5.0 % Pass  
Exposure Time 0.43 % COV ≤ 5.0 % Pass  
Reproducibility 
 
The room size of about 30 m² is greater than the minimum required. The tube voltage 
accuracy (±6.04%) was slightly higher than the requirement (±6%)but is acceptable. 
The reproducibility of tube voltage, time and exposure were 0.1%, 0.43%, and 0.1% 
respectively. These are less than the tolerance ±5%. The HVL measured at 80 kV was 
3.64 mm Al which is greater than the minimum (2.3 mmAl) recommended and the 
leakage were not detectable by the measuring instrument meaning that is was less than 
1.00 mGy /h. 
 These results show that, the two fluoroscopy machines are functioning well and the 
measurement taken can be reliable. 
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4.3. Patients and Radiologists Dose in Radiology Department 
Radiation dose to radiologist was evaluated for 8 different types of diagnostic procedures 
carried out on 118 patients. The number of patients per type of procedure is presented in 
table 4.9. 
Table 4.9: Summary of procedures and dose measurements 
 
Procedures Abbreviations Number of Frequency of 
(performed by) procedures procedures 
Hysterosalpingography HSG 74 63.8 
(RAD 2 &3) 
Retrograde Urethrogram RUG 26 22.4 
(RAD 1) 
Mituriting Cysto-Urethrogram MCUG 9           7.7 
(RAD 1) 
Fistulogram FIST 3 2.6 
(RAD 4) 
Myelogram  1 0.9 
(RAD 4) 
Sialogram  1 0.9 
(RAD 4) 
Barium Meal BM 2 1.7 
(RAD 4) 
TOTAL  116 100 
*RAD 1, 2, 3 & 4 means Radiologist 1, 2, 3 & 4 
 
Table 4.9 shows that the most performed procedure was HSG with 63.8 % followed by 
RUG (22.4 %) and MCUG (7.7 %). Because of the high number of procedures, HSG 
procedures were conducted by two radiologists (RAD 2 and RAD 3). RUG and MCUG 
procedures were performed by one radiologist (RAD 1) and other procedures such as 
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barium meal, barium enema, myelogram, sialogram and fistulogram also called special 
cases in the department were conducted by one Radiologist (RAD 4). These procedures 
however, are not frequent. 
4.3.1. Patient Dose and Fluoroscopy Time  
The mean, median and range of patient dose (KAP) and fluoroscopy time of each type of 
procedure performed in radiology department are presented in table 4.10. 
Table 4.10: Mean, median and range values of KAP and fluoroscopy time for each 
procedure. 
Procedures KAP (Gy.cm²) Time (min) 
 Mean Median Range Mean Median Range 
RUG 6.7 5.6 3.5 – 16.8 0.7 0.6 0.3 – 1.6 
MCUG 13.9 13.4 2.2 – 23.7 1.8 2.0 0.4 – 3.1 
RUG +MCUG 40.7 41.0 37.1 – 44.1 1.5 1.5 1.2 – 1.9 
H S G 6.0 5.7 1.9 - 14.4 0.7 0.6 0.2 - 2.5 
FIST  35.0 30.2 8.7 – 66.1 1.9 1.4 1.4 – 3.0 
Myelogram 
25.6 10.3 10.3–40.8 3.4 1.9 1.9 – 4.8 
and Sialogram 
Baruim meal 41.1 21.5 21.5–60.8 7.2 3.5 3.5– 10.9 
 
The lowest fluoroscopy time range are [0.3 – 1.6] min and [0.2 – 2.5] min and the 
corresponding patient dose range are [3.5 – 16.5] Gy.cm² and [1.9 – 14.4] Gy.cm² were 
recorded for RUG and HSG procedures respectively. This can be attributed to the fact 
that those procedures are simple, fast and require the lowest number of image acquisition 
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(between 2 – 4 images). This observation is contrary to combined RUG + MCUG, FIST, 
myelogram and sialogram procedures which have almost the same time range and with 
high patient dose. The high patient dose recorded can be the result of the high number of 
image acquisition obtained during these procedures. Barium meal was found to be the 
lengthier procedure administering the highest dose to the patients. This procedure is 
performed on babies, so the length depends on how stable the baby is and require many 
image acquisitions than screening mode. A good example shown in this table was 
performed in 10.9 minutes and the recorded KAP was 60.7 Gy.cm² on a ten months baby 
female. A total of 16 images and 95 frames were recorded for this specific procedure 
without collimation. 
In general, patient dose and fluoroscopy time are not uniformly distributed. Table 4.10 
shows that patient dose varies with different type of procedures, not necessary with the 
fluoroscopy time. Also, for the same procedures, these two quantities vary for different 
patient. This observation lets conclude that patient dose depends on many other factors 
such as the complexity in patient anatomy, patient size, etc.                                 
4.3.2. Radiologist Dose and Workload 
Table 4.11, 4.12, 4.13 and 4.14 represent the daily number of procedures, fluoroscopy 
time, the estimated effective dose using three (3) different methods (one dosimeter out 
leads, one outside lead and double dosimetry) and the eye lens dose of RAD1, RAD2, 
RAD3 and RAD4 respectively. It also represents the number of days each radiologist 
performed procedures during the data collection. 
 
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Table 4.11:   Estimated daily effective dose (using three different methods) and eye 
lens dose to RAD 1                                                                                                                                                                                                                                                                                                                                     
 Procedures Number Time Single in Single Double E 
of cases (min) E1 (µSv) out E3 eye  
E1(µSv) (µSv) (µSv) 
Day 1 RUG 2 2 1 6.6 4.3 96.4 
MCUG 1 1.1 
Day 2 RUG 3 1.2 1 5.8 3.9 84.7 
RUG+MCUG 1 1.5 
MCUG 1 2.2 
Day 3 RUG 2 2.4 1 2.9 2.5 42.3 
Day 4 RUG 3 1.2 1 3.2 2.6 46.7 
RUG+MCUG 1 1.2 
Day 5 RUG 2 1.7 0 6.3 10.2 92.0 
MCUG 1 3.1 
Day 6 RUG 2 1.7 0 1.3 0.7 19.0 
Day 7 RUG 1 0.7 1 1.8 1.9 26.3 
MCUG 1 1.9 0 1.7 0.9 24.8 
Day 8 RUG 3 2.4 2 8.1 6.1 118.3 
MCUG 2 2.9 
 
 
 
 
 
 
 
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Table 4.12: Estimated daily effective dose (using three different methods) and eye 
lens dose to RAD 2 for HSG procedures 
 Number Time Single in Single out Double E2 E eye  
of cases (min) E1 (µSv) E2 (µSv) (µSv) (µSv) 
DAY 1 3 1.2 3 4.7 5.4 68.6 
DAY 2 4 2.5 6 12.7 12.4 185.4 
DAY 3 5 2.7 1 5.8 3.9 84.7 
DAY 4 4 2.1 1 3.6 2.8 52.6 
DAY 5 2 0.7 1 3.2 2.6 46.7 
DAY 6 5 2.9 2 8.9 6.5 129.9 
 
 
Table 4.13: Estimated daily effective dose (using three different methods) and eye 
lens dose to RAD 3 for HSG procedures. 
 Number Time Single in Single out Double E eye  
of cases (min) E1 (µSv) E1 (µSv) E2 (µSv) (µSv) 
DAY 1 3 1.2 3 3.1 4.5 45.3 
DAY 2 1 0.9 1 4.2 3.1 61.3 
DAY 3 6 1.9 1 4.4 3.2 64.2 
DAY 4 3 2.5 1 10.3 6.2 150.4 
DAY 5 2 0.6 1 7.1 4.5 103.7 
DAY 6 3 2.2 4 14.4 11.2 108.0 
 
 
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Table 4.14: Estimated daily effective dose (using three different methods) and eye 
lens dose to RAD 4. 
Procedures Time Single in Single out Double  E eye 
(min) E1 (µSv) E2 (µSv) E3 (µSv) (µSv) 
Barium meal 10.9 13 116.2 71.1 1696.5 
Sialogram 1.9 1 1.10 1.6 16.0 
Fistulogram 5.1 7 87.6 50.8 1279.0 
Follow through 3.5 1 7.4 4.7 108.0 
Barium enema 4.7 1 7.4 4.7 108.0 
Myelogram 4.8 1 12.3 7.2 179.6 
 
The number of days in tables 4.12 and 4.13 is less because HSG procedures were 
conducted by two radiologists who were working together in the room at the same time. 
The dose recording of the first day of the data collection brought awareness on their 
radiation exposure. Therefore, for optimization purpose, RAD 2 and RAD 3 divided 
themselve in such a way that one conducts procedure while the second one observe from 
the console room daily. 
 According to table 4.11, the average number of procedures performed by RAD 1, RAD 2 
and RAD 3 was found between 2 – 3 per day. In these cases only the double dosimetry 
method of estimation of the effective dose is considered for the discussion. The lowest 
dose recorded by RAD 1 were observed on day 6 with the corresponding values 0.7 µSv 
and 19 µSv for effective dose and eye lens dose. These dose were recorded performing 
two RUG procedures in 1.7 minutes. The highest doses were 6.1 µSv and 118.3 µSv 
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recorded for five procedures (3 RUG and 2 MCUG) performed in 5.3 minutes. The trend 
of this results shows that worker dose increases with the number of procedures and the 
fluoroscopy time. This assumption is not verified for RAD 2 and RAD 3 and RAD 4. The 
dose to RAD 2 performing four procedures in day 2 and day 4 were 12.4µSv and 1.8 µSv 
respectively, for five procedures on day 3 and day 6 were 4.0 µSv and 6.6 µSv. This 
same scenario where observed with RAD 3 and RAD 4. Generally, it was observed that 
dose to RAD 2, RAD 3 and RAD 4 were not uniformly distributed in function of number 
of procedures performed or the screening time.This shows that the dose to the worker is 
influenced by many other factors related the worker. 
Table 4.15 represents the monthly workload (in terms of time and number of procedures 
performed), the effective dose estimated by three (3) different methods and eye lens dose 
to radiologists.  
 
Table 4. 15: Estimated monthly workload, effective dose and eye lens dose to the 
Radiologists. 
 Total Time N° of Single in Single out Double E eye 
(min) procedures E1 (mSv) E2 (mSv) E3 (mSv) (mSv) 
RAD 1 32.10 32 0.01 0.04 0.03 0.55 
RAD 2 36.30 69 0.02 0.04 0.03 0.57 
RAD 3 37.67 69 0.01 0.04 0.03 0.53 
RAD 4 30.90 8 0.02 0.23 0.14 3.39 
 
Table 4.15 shows a great variation in the number of procedures performed by 
Radiologists: 32, 69, 69 and 8, but the screening time almost the same 32.10, 36.30, 
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37.70 and 30.90 minutes respectively. this imply that the screening time is not figured by 
the number of procedure, it depend on the type of procedure and the anatomy of the 
patient. RAD 4  has recorded the highest effective dose and eye lens dose (0.11 mSv and 
3.39 mSv) even though having the smallest workload. This can be attributed to the poor 
application of protective measures and also the position occupied (very close to the 
patient and to the direct beam) when performing the procedure. But RAD 1, RAD 2 and 
RAD 3 recorded the same amount of effective dose and eye lens dose . This was 
predictible from the patient dose and fluoroscopy time analysis done in section 4.3.1. 
Where it was found that dose delivered to patients and fluoroscopy time were almost 
similar RUG, MCUG and HSG were in the same range. The result of the estimated 
effective dose using three differents methods agree with ICRP assumption saying that, 
“dose monitoring with one dosimeter placed inside lead apron underestimate the dose 
(ICRP, 2000). A dosimeter worn outside lead will overestimate the dose and the  best 
way to monitor the workers conducting fluoroscopy procedures is the double dosimetry 
in case of hight radiation exposure.” 
The monthly dose  compared with ICRP recommendation (ICRP, 2007) is presented in 
figure 4.1. 
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4
3.5
3
2.5 E1
2 ICRP Limit = 1.667 mSv
E2
E3
1.5
E (eye)
1
0.5
0
RAD 1 RAD 2 RAD 3 RAD 4  
Figure 4.1: Estimated effective and eye lens dose compared with ICRP limit 
 
Both effective dose and eye lens dose to RAD 1, 2 and 3 were found far below (42 times 
less for effective dose, 3 times less for eye lens) the limit regardless the method used for 
estimation. In the same line, effective dose to RAD 4 was below the limit (by a factor 12) 
but the dose to the lens of eye has double the limit. It has exceeded to the investigation 
level (2 mSv/ month) proposed by Duran et al (2013). An investigation should be 
carrying out to this particular worker to check the circumstances that lead to that high eye 
dose. The purpose of which is to keep the dose As Low As Reasonable Achievable 
(ALARA).  Because of the proximity of Radiologists to the patient, for some procedures 
the hands of some radiologists were exposed to the direct beam. Therefore, are likely to 
received high radiation doses. The monitoring of Radiologists hands is required  
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4.4. Patients and Cardiologists Dose in Cathlab 
Table 4.16 shows the number of procedures that have been carried out by Cardiologists in 
cathlab of KBTH during the period of data collection (two months). Figure 4.2 presents 
the frequencies of procedures in the laboratory. 
Table 4. 16: Number of procedures performed by cardiologists during the period of 
data collection. 
 
Procedures Abbreviations N° cases 
Coronary Angiogram CA 30 
Right Heart Catheterization RHC 6 
Percutaneous Coronary PCI 14 
Angiogram 
TOTAL  50 
 
CA
14
18 RHC
54
PCI
14
CA + PCI
 
Figure 4.2: frequency of procedures in the cathlab 
 
Coronary Angiogram is a diagnostic procedure and is the most performed in the cathlab. 
It is sometime associated with intervention procedures (PCI). RHC is a procedure used to 
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check heart pressure of patients and it is done only for few patients who are programmed 
for surgery.  
4.4.1. Patient Dose and Fluoroscopy Time 
The KAP and fluoroscopy time were recorded by means of integrated KAP meter. The 
median, range values for investigated procedure are presented in table 4.17. 
 
Table 4.17: Median and range values of KAP and fluoroscopy time for each 
procedure performed in cathab. 
   KAP (Gy/cm²)                Time (min) 
A  Procedures Median Range Median Range 
 CA 27.2 14.2 - 120.6 3.9 1.7 - 16.3 
 PCI 112.5 60.0 - 117.2 26.9 13.5 - 43.0 
 CA + PCI 134.8 42.0 – 237.0 19.9 9.7 - 37.5 
 RHC 5.8 4.4 - 33.6 4.8 4.3 - 11.8 
large variation of DAP and screening time among procedures are observed. KAP ranges 
from 4.4 Gy.cm² (Right heart catheterization) to 237.0 Gy.cm² (combined CA + PCI). 
Fluoroscopy time ranges from 1.7 minutes (CA) to 43 minutes (PCI). Significant 
variation was also observed for different types of procedures for example, for CA 
procedure the minimum and maximum values of DAP and fluoroscopy time are 14.2 
Gy.cm², 1.7 minutes and 120.6 Gy.cm², 16.3 min respectively. This large variation is 
observed for other type of procedure. This could be attributed to the complexity of patient 
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anatomy, the technique of the doctor, the number of cine and the patient – tube distance 
and angulation used. Patients undergoing PCI and CA + PCI procedures are likely to 
receive the highest dose, median DAP are 11.47 Gy.cm² and 134.8 Gy.cm², median 
fluoroscopy time are 26.9 minutes and 19.9 minutes respectively.  
4.4.2. Cardiologists Doses  
Contrary to Radiologists to whom is allocated specific type of procedures, Cardiologists 
are performing every type of procedure depending on their availability when patients are 
ready. Every procedure is performed by two Cardiologists present near the patient. The 
range of dose per procedures for different type of procedure conducted by Cardiologists 
is given in table 4.18. 
Table 4.18: Effective dose per procedure to Cardiologists 
 
 CA (µSv) PCI (µSv) RHC (µSv) 
Card 1 0.3 – 2.1 1.8 – 6.9 - 
Card 2 0.15 – 21.1 1.2 – 57.6 2.3 – 2.5 
Card 3 0.85 – 15.9 0.9 – 6.4 0.1 – 1.9 
Card 4 0.05 – 5.7 0.8 – 2.5 0.3 – 2.8 
Combined 0.05 – 21.1 0.8 – 57.6 0.1 – 2.8 
 
As expected, owing to patient dose presented in section 4.4.1, the dose range for RHC 
procedures is very lower (minimum 0.1 µSv, Maximum 2.8 µSv) than the dose range for 
other procedures. Morrish and Goldstone in (2008) estimated the dose to Cardiologists 
and found a range of (0.02 – 30.2) µSv per procedure for CA examinations and (0.17 – 
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31.2) µSv per procedure for PCI. In the same line Fardid et al in (2013) found the dose 
range per procedure to cardiologists for CA (0.3 – 14.3) µSv and (1.3 – 27.5) µSv for 
PCI. In general, the dose range received by all Cardiologists per procedures was 0.05 µSv 
to 21.1 µSv which is comparable to the range value of (0.2 – 18.8) µSv and (0.02 – 38.0) 
µSv obtained by Padovani and Rodella in (2001), Kim et al in (2008) respectively. The 
wide range of dose for each Cardiologist is attributed to the position of the Cardiologist 
from the patient, whether the Cardiologist is acting as an assistant or principal operator 
and the protective equipment used. 
The number of cases per type of procedure conducted by each Cardiologist is presented 
in figure 4.3. 
8
7
6
5
4
3
2
1
0
Card 1 Card 2 Card 3 Card 4
 
Figure 4. 3: Number of procedures conducted by Cardiologists Monthly 
 
PCI and CA + PCI are mostly performed by Card 1 and CA by Card 2 and Card 3. Card 1 
because of the expertise was always working as the principal operator and Card 4 as the 
assistant. From figure 4.3, Card 2 and Card 4 were the most frequent in the room with 12 
procedures conducted by each, following by Card 1 with 10 procedures and lastly Card 3 
with 7 procedures. To investigate the impact of each type of procedure on workers dose, 
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Number of procedures
CA
PCI
CA + PCI
RHC
CA
PCI
CA + PCI
RHC
CA
PCI
CA + PCI
RHC
CA
PCI
CA + PCI
RHC
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the dose received by Cardiologists for each type of procedure was estimated and is 
presented in figure 4.4 below. 
 
180
160
140
120
100
80
Effective dose
60
Eye lens dose
40
20
0
Card 1 Card 2 Card 3 Card 4
 
Figure 4.4: Estimated effective dose and eye lens dose to Cardiologists for different 
type of procedure 
 Figure 4.4 shows that the dose received by Card 4 for every type of procedure is far 
lower than the dose received by Card 2 even though they performed the same number of 
procedures. In the same perspective, the dose received by Card 1 conducting two 
procedures of CA +PCI, is lightly the same received by Card 2 conducting only one 
procedure. For the same number of RHC procedures conducted, it is observed that the 
dose received by Card 4 is almost two time the dose received by Card 3. Generally, all 
the great variation of dose to each Cardiologist per type of procedure owned to the fact 
that there is an inconsistency in the position occupied by different operators in the 
examination room. The most important observed fact is that most of RHC procedures 
were performed by Card 4 as principal operator and other were working as assistant. For 
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Effective dose (µSv)
CA
PCI
CA + PCI
RHC
CA
PCI
CA + PCI
RHC
CA
PCI
CA + PCI
RHC
CA
PCI
CA + PCI
RHC
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Card 1, PCI procedure is the most contributors in terms of dose (both effective and eye 
lens dose) because the complexity of the procedure and to the fact that, this particular 
Cardiologist always work as principal operator. For other Cardiologists, the CA 
procedures are the most contributors to the dose.  
An average of 22 procedures was performed in the cathlab per month. The monthly 
workload (time and number of procedures) effective dose and eye lens dose to 
Cardiologists has been estimated and is presented in table 4.19. 
 
Table 4.19: Monthly effective dose and eye lens to the Cardiologists 
 
 Fluoroscopy N° of Double  Eye lens  
Time (min) procedures E (mSv) Dose (µSv) 
Card 1 177.0 10 0.02 0.30 
Card 2 129.0 12 0.07 0.25 
Card 3 77.1 7 0.02 0.20 
Card 4 109.2 12 0.01 0.15 
 
Because of various types of procedures, some are lengthier and complex than other. An 
example is the comparison between the fluoroscopy time and the number of procedures 
performed by Card 1 (10 procedures, 177 minutes) and Card 4 (12 procedures, 109.15 
minutes). Comparing the screening time to the effective dose, Card 1 has the highest 
workload, but effective dose is half of the dose to Card 2 who has a workload of 129 
minutes and the same with Card 3 who has a workload of 77.1 minutes. But the eye dose 
to Card 1 were found to be the highest (0.3 mSv) among all the Cardiologists. Highest 
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eye dose and low effective dose show an adequate lead apron wear by Card 1. Card 2 
record the highest effective dose because of his proximity to the patient during procedure. 
The lowest value of doses (0.01 µSv for effective dose and 0.15 µSv for eye lens) was 
recorded by Card 4 can due to the fact that mostly working as assistant operator.  
In general, the low values obtained in this can be attributed to the small number of 
procedures conducted in this particular cathlab. The amount of radiation received by 
every worker depends also on the level of protective measure taken individually. The 
estimated annually dose was compared to the limit recommended by ICRP and is 
presented in figure 4.5 below (ICRP, 2007).  
20
18
16
14
12
Eye lens dose
10
8 Effective dose
6
3.81
4 3.05 2.43 1.85
2 0.23 0.81 0.26 0.16
0
Card 1 Card 2 Card 3 Card 4  
Figure 4.5: Estimated annual effective dose and eye lens dose compared to ICRP 
limits 
The annually estimated effective dose and eye lens dose to the Cardiologists was found 
very low to ICRP recommended annual dose limit of 20 mSv (ICRP, 2007). These results 
are high compared the one obtained by Efstathopoulos et al (2003) who obtained a range 
of (0.04 – 0.03) mSv per year for principal operator considering a workload of 240 
procedures.  On the other hand, the estimated effective dose (0.16 – 0.81) mSv was 
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comparable to those published by UNSCEAR 2000 (0.4 mSv per year). The reported 
dose by Dendy (2008) was 2 – 4 mSv per year considering a workload of 1000 
procedures. In 2009 Martin reviews the dose to cardiologists and found the dose per 
procedure between 0.2 and 4 µSv (few were found at 19 µSv) to the whole body and 
around 20µSv for the lens of eye. He assumed that for 500 procedures each year, 
Cardiologists are likely to receive between 0.1 and 4 mSv per year. The projected number 
of procedures per Cardiologists in this study is averaged at 123 procedures per year, 
which is the quarter of what proposed by Martin. This can be the reason for low dose 
obtained in this study. 
 
4.4.3. Risk Assessment to Cardiologists 
The probability of cancer induced and heritable effect (or total detrimental risk) due to 
radiation exposure received by Cardiologists in this study was calculated using ICRP 
2007 for individual risk coefficient and is presented in figure 4.6 below. 
0.04
0.035
0.03
0.025
0.02
0.015
0.01
0.005
0
Card 1 Card 2 Card 3 Card 4
Cancer Heritable effects Total Detriments Risk
 
Figure 4.6: Estimated risk to Cardiologists 
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 Due to the fact that the dose to Cardiologists was estimated for only one year, the risk 
estimation done in this study is very negligible. In addition, the workers are exposed to 
radiation during their life time.  
 In general, the estimated probability of health effect due to radiation to Cardiologists is 
not significant but should not be ignored. The LNT model assume that every amount of 
radiation (as small it can be) carries with it risk of cancer or heritable effect. Therefore, 
there is the need to enhance radiation protection actions in other to keep the dose As Low 
As Reasonably Achievable and reduce the likelihood of stochastic effects.  
4.4.4. Relationship between Effective Dose and Patient Dose 
The investigation into the relationship between patient dose (DAP) and Effective dose is 
given in figure 4.7. 
70
y = 0.6487e0.0159x
60
R² = 0.3289
50
40
30
20
10
0
0 50 100 150 200 250
KAP (Gy.cm²)
 
Figure 4.7: Relationship between Effective dose and patient dose 
 
The plot of exponential relationship between KAP and effective dose gave the following 
equation 4.3: 
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𝑌 (𝑒𝑓𝑓𝑒𝑐𝑡𝑖𝑣𝑒 𝑑𝑜𝑠𝑒) =  0.6487 ×  𝑒0.0159 × 𝐷𝐴𝑃   With   R² = 0.32     (4.3) 
Figure 4.7 shows that below KAP value of 150, the relationship between KAP and 
effective dose is likely to be linear. Looking at the previous equation 4.3, the value of R² 
shows that the relationship in general is weak, showing that the effective dose is 
influenced by other factors which have been stated in previous sections. The regression 
analysis of these two parameters gives a significant level (P – value = 0.012 < 0.05) 
meaning that this relationship is statistically significant, and the probability that it is 
related to chance is 0.012 which is very small. The linear relationship derived from the 
statistical analysis is following equation 4.4. 
 𝑌 (𝑒𝑓𝑓𝑒𝑐𝑡𝑖𝑣𝑒 𝑑𝑜𝑠𝑒) = 0.073 × 𝐷𝐴𝑃 + 0.2962   with R² = 0.15.         (4.4) 
The p – value of the intercept is 0.89 which is greater than 0.05. This means that the 
intercept is more related to chance, so not reliable. This may be attributable to the non - 
uniform distribution of effective dose caused by the influence of another factor such as 
shielding, etc.  
4.5. Investigation into other Factors affecting Workers Dose  
A comparison of Cardiologists and Radiologists effective dose and eye lens dose against 
the workload presented in tables 4.15 and 4.19 in the previous sections shows that the 
workers are most exposed to radiation with over couch fluoroscopy tube than under 
couch tube. To support this statement, the Interventional Radiologist (IR) and the 
Assistant have been monitored during two procedures using the two configuration of the 
fluoroscopy tube and the results are given in table 4.20. The biliary drainage was 
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performed with over couch tube in radiology department and biliary stenting was 
performed with under couch tube at the cathlab. 
 
Table 4.20: Dose records of interventional radiology procedures with overcouch and 
undercouch tube. 
   IR Assistant IR 
Procedures DAP Time Effective Eye Dose Effective Eye Dose 
Gy.cm² (min) Dose (mSv) (mSv) Dose (mSv) (mSv) 
Biliary 
47.13 14.3 0.04 0.53 0.02 0.22 
drainage 
Biliary 
412.23 76.4 0.05 0.67 0.01 0.11 
stenting 
 
Biliary drainage procedure performed in the radiology department with fluoroscopy time 
of 14.3 minutes, the IR received 0.04 mSv and 0.53 mSv for effective dose and eye lens 
dose respectively. These values are lower (with a factor 1.25) than the dose received by 
the same IR (0.05 mSv and 0.67 mSv for effective dose and eye lens dose respectively) 
during 76.4 minutes (five times the screening time of biliary drainage). This high dose 
received in short time in the radiology department may be attributable to the geometry of 
the tube and the absence of additional shielding (lead glass and lead curtain) in radiology 
department. The assistant recorded half of the dose received in the radiology department 
owing to his position from the patient in the cathlab. The variation in staff effective doses 
for the same procedure can be attributed to the expertise of the worker and the protective 
garment used. The effect of the worker position in the room and the tube angulation 
during examination would be further explained in the following section. 
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4.6. Scattered Radiation in the Examination Room (Cathlab) 
4.6.1. Modelling of the room 
The X-ray source was modeled in a capsule made up of lead and placed under the patient 
couch. The modeled phantom was placed on the couch. It is shown in figure 4.8 below. 
Patient couch 
a) b) 
Figure 4.8. Source, patient table and phantom modeled with Simple Geo software 
 
The room was modeled in respect with the measures taken at the real cathlab. The top 
and side views are presented in figure 4.9. 
 
Figure 4. 9. Top and side view of the cathlab modeled with Simple Geo software 
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4.6.2. Distribution of Radiation in the Room for AP 0° of the Source 
The file created by the Simple Geo was exported in MCNP 6 for simulation. Results were 
plotted using GnuPlot at different height from the floor of the source. The plots are 
presented in figures 4.10 and 4.11 below. 
y 
x 
 
Figure 4.10: Dose distribution in the room at 85 cm from the floor 
 
y 
x 
 
Figure 4.11: Dose distribution in the room at 107 cm from the floor 
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Figure 4.10 represents radiation distribution under the patient couch before any 
interaction, it shows that radiation is more concentrated around the patient couch and is 
spread all over the room. The safest place is negligible. This is the reason why a lead 
curtain must be always used to protect the operator’s legs.  
Figure 4.11 is the scattered radiation distribution at the level of the patient couch which is 
likely to be the trunk level of the operator. At this level the direct beam has interacted 
with the patient table and other materials on the patient couch. It can be observed that the 
safest place at the back of the room, behind the equipment is larger than the distribution 
at 85 cm. Also, the area of maximum radiation is smaller than the one at 85 cm, but it is 
around the table where the operator stays. It shows the importance of wearing lead apron 
properly. In both cases the nurses and any other person staying in the room are exposed 
to radiation. Therefore, they should also wear the protective garment. The head of the 
operator is the unshielded part of the body exposed to radiation. Figures 4.12 and 4.13 
represent the distribution at the head level of the operator (150 cm and 171 cm) 
y 
x 
 
Figure 4.12: Dose distribution in the room at 150 cm from the floor 
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y 
x 
 
Figure 4.13: Dose distribution in the room at 171 cm from the floor 
 
At 150 cm in figure 4.12, the safer place in the room is larger than at 171 cm on figure 
4.13. The more it goes higher the more radiation is spread all over in the room and the 
maximum region is directed toward the entrance of the room where the nurse are likely to 
stay. Therefore, the taller nurses are likely to receive more radiation to the head (eye lens) 
than the operators staying near the patient. In general, everyone staying in the 
examination room is not safe. Thus, the safety measures must be applied by the operators 
and the nurses at the same level. The lead glass screen is one of the protective measures 
taken to reduce radiation to the head and hands of the operators. 
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4.6.3. Distribution of Radiation in the Room for LAO 30° and RAO 30° of the 
Source 
The staff exposure is more influenced by the tube angulation used during procedures. 
Figures 4.14 and 4.15 represents the distribution at LAO 30° and RAO 30° of the source.  
y 
x 
 
Figure 4.14: Dose distribution (LAO 30°) at 171 cm from the floor 
 
Figure 4.15 shows that, there is no safe area in the room and the highest radiation is 
concentrated on the operator side. Therefore, the operators are more exposed to radiation 
when using the LAO anterior position of the tube. 
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y 
x 
 
Figure 4.15: Dose distribution (RAO 30°) at 171 cm from the floor 
 
For RAO 30° positions shown in figure 4.15, radiation is more concentrated at the 
opposite side of the operator.  
4.6.4. Measured Values of the Scattered Radiation 
The measured values of scattered radiation are presented in table 4.21 below. The 
operator’s position is 180° at the right side of the patient. 
 
Table 4.21: Measured values of scattered radiation 
 
 0° (mSv/h)  90° (mSv/h) 180° (mSv/h)  270° (mSv/h)  
AP 0° 0.48 0.36 0.52 0.48 
 
RAO 30° 1.08 0.60 0.54 1.56 
 
LAO 30° 0.42 0.72 1.50 1.14 
 
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Table 4.21 shows that operators are more exposed to the radiation when the tube is at the 
position LAO 30°. These results agree with the computation in term of the most exposed 
and the safest area in the room. 
Generally, every staff present in the room during the procedure is exposed to radiation 
especially to the head. Therefore, more protective actions (such as: additional shielding, 
stay at the safer position, etc) should be applied to keep the dose As Low As Reasonably 
Achievable.  
4.7. Limitations of the study 
The data was intended to be collected at least for two months in the Radiology 
Department but because of the delay in acquiring the ethical clearance and the 
dosimeters, the data was collected for only one month. An improvised water phantom 
was used for the scatter radiation measurement because of the unavailability of 
anthropomorphic phantom. The time allocated for the study was very limited to conduct a 
comprehensive risk assessment. Thus, a significant value of risk to the worker could be 
found in a study accounting for many years. 
 
 
 
 
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CHAPTER FIVE 
5.0. Conclusion and Recommendations 
Recent progresses in technology have resulted in the development and increased use of 
ionizing radiation for the purpose of diagnostic and treatment particularly in fluoroscopy. 
However, the awareness of the health effect of ionizing radiation should be considered 
and actions must be considered to reduce patient and staff dose. This chapter presents the 
general conclusion of this study and some recommendations emanating from the findings. 
 
5.1. Conclusion 
In this study, the effective dose and eye lens dose to four Radiologists using over couch 
fluoroscopy tube and four Cardiologists using under couch fluoroscopy tube was 
estimated using the double dosimetry method at KBTH and compared to other study 
using the same monitoring methods. 
The effective dose and eye lens dose to the Radiologists were found lower than the limits 
recommended by ICRP except the eye lens dose to Rad 4 that was found higher by the 
factor 2. Therefore, monitoring of Radiologists eye lens for the identified specific 
procedures need more attention. The use of ceiling suspended glass and lead curtain 
would reduce the dose to the unshielded part such as eye, head, etc. therefore it is highly 
recommended for use in this department.   
Dose to Cardiologists were comparable to other study, but were found far lower than 
ICRP dose limit (1.667 mSv). The effective dose and eye lens dose were not uniformly 
distributed. The interventional procedures were found to be lengthier, delivering 
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relatively high doses to patients. Therefore, the dose per procedure to the Interventional 
Radiologist was higher than other staff working in the same environment. 
 The main factors that influence staff dose were observed to be: procedure types 
due to the access route used, geometry of the X-ray tube (staff are more exposed to 
radiation using over couch tube than under couch tube), position of the operator in the 
room during procedures, the tube angulation, and the experience of the staff. The most 
critical factor is the use of protective garment used by each operator. Occupational 
exposure is significantly influenced by patient exposure. Therefore, actions to reduce 
patient dose will also contribute to operator protection.  
 The risk assessment shows that, no dose should be considered safe because any 
amount of radiation carries with it a risk. 
 The Monte Carlo simulation of dose distribution in the room shows that, at certain 
height, the nurses are more exposed to the eye lens than the operators for AP0° and there 
is no safe position in the examination room. On other hand the operators are exposed to 
high radiation for LAO position of the tube and are safe for RAO position of the tube.  
Therefore, staffs are advised to wear protective equipment at all times dring procedures.   
Optimization of protection (describe in the radiation safety programme proposed in 
appendix 6) should be considered by the operator to maximize patient safety keeping the 
dose ALARA without compromising the clinical outcome of the procedure. 
 
5.2. Recommendations 
Optimization in fluoroscopy is complex due to the complexity of procedures and the 
many technical factors that influence the dose. Therefore, training and quality assurance 
are indispensable. Because of the complexity of equipment used, quality control of the 
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many parameters involved is time consuming and a careful selection of the parameters to 
be controlled in constancy checks and frequency are essential part of the programme.  
 
5.2.1. Establishment of a Radiation Safety Programme 
The results of the investigation performed in both departments concerning radiation 
protection practice in section 4.1 shows insufficient radiation protection and safety 
measure considerations. The risk associated with low radiation exposure emphasizes the 
need for adequate measures to minimize patient and staff dose. This can be possible 
through the development and implementation of a radiation safety programme. 
This study recommends the implementation of the proposed radiation safety program 
(Appendix 6). It is adopted from ICRP publication 139, Chamber et al (2011) and the 
purpose of this program is to increase the awareness of safety related to procedures 
involving radiation in other to provide to patient and all staff involved with radiation a 
safest environment possible for the best clinical outcomes.  
 
5.2.2. Recommendation for Further Study 
This study was limited by the duration, the type of dosimeter used and the collaboration 
with the administration and personnel. Therefore, the following are proposed for further 
study. 
 This study was limited to occupational radiation exposure. However, high patient 
dose and long fluoroscopy time were recorded especially for interventional 
procedures. This shows the necessity to carry out a detailed and complete study 
on patient dose assessment in the catheterization laboratories in Ghana. In 
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addition, the growing number of procedures and the new operating cathlab created 
show the importance of establishing the dose reference level for the most 
performed cardiac catheterization procedures (CA and PCI) in Ghana. 
 A study base measurements and Monte Carlo simulation aiming to develop an 
algorithm to accurately estimate effective dose to operators in Ghana using double 
dosimetry method. 
 
 
 
 
 
 
 
 
 
 
 
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Ciraj‐Bjelac, O., Rehani, M. M., Sim, K. H., Liew, H. B., Vañó, E., Kleiman, N. J., 
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there reason for concern?” Catheter Cardiovasc Interv. 2010;76(6):826-834. 
 
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“Radiation-Induced Eye Lens Changes and Risk for Cataract in Interventional 
Cardiology.” Cardiology, vol. 123, no. 3, pp. 168-171, Oct. 2012. 
 
Ciraj-Bjelac, O., and Rehani, M. M. “Eye Dosimetry in Interventional Radiology and 
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Dosim., vol. 162, no. 3, Nov. 2013. 
 
 
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              Covens, P., Berus, D., Buls, N., Clerinx, P., and Vanhavere, F., “Personal dose 
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dose reduction based on radiation-protection training,” Archives of 
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Martin, C. J.  "A review of radiology staff doses and dose monitoring requirements." 
Radiation Protection Dosimetry, 2009; 136(3), 140-157. 
 
Martin, C.J., Magee, J.S. “Assessment of eye and body dose for interventional      
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radiology.” CardioVascular and Interventional Radiology, vol. 33, no. 2, pp. 
230–239, 2010. 
 
Morrish, O. W., Goldstone, K. E. “An investigation into patient and staff doses from X-
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Niklason, L. T., Marx, M. V. and Chan, H. P. “The estimation of occupational effective 
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NCRP. “Use of Personal Monitors to Estimate Effective Dose Equivalent and Effective 
Dose 1063 to Workers for External Exposure to Low-LET Radiation.” NCRP 
Report No. 122. The 1064 National Council on Radiation Protection and 
Measurements, Bethesda, USA, 1995. 
 
NCRP, “Radiation Dose Management for Fluoroscopically Guided Interventional 
Medical Procedures.” NCRP Report No. 168. National Council on Radiation 
Protection and Measurements, Bethesda, MD 2010. 
 
Nuclear Regulatory Authority, “Major Radiographic X – ray Tquipment Test Sheet,” 
Accra, Ghana, 2016. 
 
Padovani, R., Fiti, C. and Malisan, M. R.“Staff dosimetry protocols in interventional 
radiology.” Rad. Prot. Dosim. 94, 193–196, 2001. 
 
Padovani, R., Rodella, C. A, “Staff dosimetry in interventional cardiology.”  Radiat Prot 
Dosimetry 2001; 94:99–103. 
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Padovani, R., Le Heron, J., Cruz-Suarez, R., Duran, A., Lefaure, C., Miller, D.L., Sim, 
H.K., Vano, E., Rehani, M., Czarwinski, R., “International project on individual 
monitoring and radiation exposure levels in interventional cardiology.” Radiat 
Prot Dosimetry. 144, 437–441. 2011. 
 
Picano, E., Vano, E., Semelka, R., and Regulla, D., “The American College of Radiology 
white paper on radiation dose in medicine: deep impact on the practice of 
cardiovascular imaging,” Cardiovascular Ultrasound, vol. 5, article 37, 2007.  
 
Raczynski and Sadowski, M., “Radiation exposure, Dosimetry and staff protection in 
catheterization laboratory.” J Med diagn Meth, 2013. 
 
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Tsimikas, S., Patel, M. P., Mahmud, E. “ Invasive cardiologists are exposed to 
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Intervent 2015. 
 
Rehani, M.M., Ciraj-Bjelac, O.,  Vano, E., Miller, D. L., Walsh, S., Giordano, B. D. and 
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interventional procedures. “ Am. J. Cardiol. 111, 1368–1372. 2013. 
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Sandblom, V., Mai, T., Almén, A., Rystedt, H., Cederblad, A., Båth, M., and Lundh, C. 
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and Kappas, C., "Radiation dose optimisation and risk estimation to patients and 
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cardiology: final results of the ORAMED project." Radiation Measurements, vol. 
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APPENDIX 1: Approval Letters 
 
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APPENDIX 2: Data Collection Sheet 
1. Patient’s Data 
Procedures DAP Exposure time Field size 
    
 
2. Worker’s  Data 
Procedures workers Neck Neck Chest 
Hp(10) Hp(0.07) Hp(10)  
     
 
3. Availability of Radiation Protection Equipment 
 Identification of the X-ray unit (characteristic and parameters) 
 Availability of personal protection 
- Lead apron 
- Thyroid collar 
- Gloves 
- Lead glasses 
 Presence of additional protection 
4. QC data Parameters 
 Beam quality (HVL) 
 Tube voltage, accuracy and reproducibility 
 Tube current exposure time product (mAS) 
 collimation 
 Output consistency and linearity 
 
5. Scatter dose measurement 
 
 0° (µSv/h) 90° (µSv/h) 180° (µSv/h) 270° (µSv/h) 
AP 0°     
RAO 30°     
LAO 30°     
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APPENDIX 3: Questionnaire  
PART A: General Information  
 
1. Name of Department:  
2. a. Responsibility of respondent:  
    b. For how long have you worked in radiology service?  
 
3. Are you aware of radiation protection of workers?  
4. What practices of staff protection do you know?  
5. What practices does the department undertake?  
 
 
PART B: Department Information  
 
6. Information of fluoroscopy X-ray tube used: 
7. Date of installation_____________________________  
8. a. Is there a Quality Assurance Program in the Department?  
    b. How frequent do you perform QC tests?  
9. Is there a radiation safety committee or a radiation protection officer (RPO) in the 
department?  
10. Is there any external expert who offers advice on radiation protection to the 
department?  
12. Are areas in your facility designated as controlled and supervised areas?  
13. Are there local rules in the department?   
14. Are there radiation warning signs in the facility?  
15. Are there warning lights at the entrance door to the X-ray room?  
 
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PART C: Personnel Protection  
 
16. How many workers are in this department?  
 
Radiologists: _______________  
Radiographers:______________  
Medical Physicists____________  
Nurses:_____________ 
17. How many female workers are in the department?  
18. Any rules for pregnant workers?  
19. What protective wear are workers given?  
        a. Lead aprons  
        b. Lead gloves  
        c. Gloves, lead glasses  
20. Number of working days per week: 
21. Average working hours (in the X-ray room) per day.  
22. a. Are occupational doses monitored?  
      b. How are occupational doses monitored?  
      c. How frequent are they monitored?  
23. How many workers have ever attended radiation protection training?  
24. Are there staff exposure and health surveillance records?  
25. a. Do you conduct radiation surveys or assessments around the working area?  
      b. How frequent?  
28. Any emergency response mechanisms in place at the facility?   
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APPENDIX 4: Calibration Certificates 
 
 
 
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APPENDIX 5: Quality Control Results from Pirhana 
 
 
 
 
  
 
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APPENDIX 6: Radiation Safety Programme for Occupationally Exposed 
Workers in Fluoroscopy Guided Procedure 
1.0. Introduction 
The improvement in technology results in the increase of number of procedure and 
number of facilities performing fluoroscopy procedures (for diagnostic and treatment). 
Thus, it is important that everyone involve with radiation receives radiation as low as 
possible. Therefore, it is a mandate for every x – ray department to have an implemented 
Radiation Safety Program for the safeguard of personnel and public from radiation 
exposure. 
The following radiation safety program provides guidelines designed to ensure staff 
awareness on radiation health risk, also tools and knowledge for the best practice in 
radiation dose management. It will help the administration and staff to have knowledge 
and education in place to maintain safe radiation dose. Establishing this program should 
be a collective effort involving hospital administration and all staff involve with 
radiation. The target groups of this program are: the Medical Director of the hospital, the 
Director of NCTC, the Head of radiology department, Radiologists, Cardiologists, 
Nurses, Radiation Safety Officer (RSO), personnel dosimetry services, Radiographers, 
everyone interested with occupational exposure in fluoroscopy guided procedures. 
2.0. Responsibilities 
The Medical Director of the hospital has the overall responsibility for protection and 
safety of the member of staff involve with radiation. He must be part of the effective 
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implementation of radiation safety program and provides financial and adequate support 
to sustain a reasonable program while ensuring all regulatory requirements for patient and 
staff safety. He should appoint a Radiation Safety Officer who will work together with 
staff members and supervises all radiation safety issues in the department.  Some of his 
responsibilities are: 
 Authorize and register the safety program 
 Review radiation safety policies and procedures 
 Monitor and review equipment and radiation warning signs 
 Evaluate individual monitoring and perform the risk assessment 
 Survey all radiation areas for safety hazards 
 Implements QA policies and procedures for X-ray equipment and personnel 
 Review and submit report of RSP annually 
 Education and training of all personnel involve with radiation 
 Establish emergency plan and procedures 
3.0. Individual Monitoring 
Occupational dose monitoring is a critical element of radiation surveillance and is 
performed to verify compliance and optimize protection. 
All staff whose work is associated with radiation must adequately and consistently wear 
their dosimeter. ICRP recommends the use of two dosimeters for operator in fluoroscopy. 
One dosimeter should be worn at waist level inside lead apron and one worn at neck level 
outside the apron. In case of the non-availability of two dosimeters for each operator, one 
should be worn outside the lead apron taking in account the unshielded part (head, 
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extremities). A separated dosimeter should be used for those personnel who work in more 
than one facility in other to identify the source of highest exposure. In case that the hands 
are exposed or work close to the direct beam, a wrist dosimeter should be considered for 
hand monitoring. The recommended dose limits are given in the following table. 
 
Table 1: ICRP dose limits (ICRP, 2007) 
Effective Dose Limits 
20 mSv per year averaged over 5 years (1.67 mSv / month) 
50 mSv in a single year  
Equivalent Dose Limits 
Lens of the eye 20 mSv per year averaged over 5 years 
(1.67 mSv / month) 
50 mSv in a single year 
Skin 500 mSv per year averaged over 1 cm²  area 
of skin regardless of the area exposed 
Extremities 500 mSv per year 
(hands and feets) 
 
In case of high exposure an investigation should be carried out to know the elements 
causing the high exposure for optimization. The investigation level proposed by WHO is 
0.6 mSv / month for effective dose. 
Variety of dosimeters can be used in personnel dose monitoring include TLDs, film 
dosimeters, etc. but for the purpose of optimization and for detailed study on dose per 
procedures, APDs are highly recommended. The calibration of the APDs should include 
the radiation field representative of those encountered in fluoroscopy including tests in 
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pulsed mode with high dose rates. The quantities used in personnel dose monitoring are 
Hp (0.07), Hp (3) and Hp (10). In case that a dosimeter calibrated in term of Hp (3) in not 
available, Hp (0.07) can be used as an approximation of Hp (3) and Hp (10) can also be 
used only for photon spectrum with mean energy above 40 keV. The assessment of 
Scatter radiation field should be performed to verify the non – compliance with the 
procedure for wearing individual dosimeters by comparing with individual dosimeter 
readings. 
Audits of occupational doses, investigation of abnormal exposure, recording, reporting 
results and corrective action if appropriate should also be considered. 
4.0. Occupational Radiation Protection and Equipment 
The action toward occupational protection is optimizing patient protection. Other means 
and actions include: the use of lead apron and thyroid collar, ceiling suspended screen 
shield and lead glasses, lead caps (if available), table suspended lead curtains and keeping 
distance from patient. A leaded drape and pad attached to the ceiling screen and be a 
mean of protection for operator hands for some specific procedures. The protective 
equipment should be characterized base on the radiation beam used to measure 
attenuation. 
Protective apron should never be folded, to avoid crack in the lining and should be 
inspected using X-ray for any defects. The integrity of lead apron should be assessed 
annually. The hospital administration should ensure that adequate resources are available 
to purchase, test and replace them. The following figures are example of a well-equipped 
cathlab and operator. 
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Figure 1: Protective cathlab an equipped personnel  
5.0. Education and Training 
Every staff member should receive radiation dose management and adequate training in 
line with their responsibilities. The RSO should coordinate in collaboration with m staff 
member initial and periodic training of newly employed and operating workers. 
Training program can be a series of online or standard classroom lectures focusing on: 
 Physics of X-ray production and interaction 
 Mode of operation of fluoroscopy machine 
 Technical factors affecting image quality in fluoroscopy 
 Dosimetry quantities and unit, biological effects of radiation 
 Principle of radiation protection , local rules and requirements 
 Techniques to minimize patient and staff dose 
Because of the relationship between patient and operator protection in fluoroscopic 
procedures, the RSO, the personnel in charge of dosimetry services, clinical application 
specialist from suppliers and regulators also require training on clinical practice and 
specifications of X-ray equipment used in addition to general radiation protection. The 
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RSO or Medical Physicist should have the highest level of training because they are 
responsible to train other staff member. 
6.0. Quality Assurance 
A well establish QA program maintain best radiation protection practices and ensure 
adequate occupational exposure control. It should include, appropriate audit, to ensure 
that personnel adhere to procedures, especially related to wearing of dosimeter, protective 
devices and method to optimize occupational protection. It should establish the 
components of performance testing which are: 
 Test to be performed, how often they are performed and acceptable limits for each 
test. 
 A brief description of be used for testing and sample forms to be used. 
Some X-ray tube and generator test that can be carried out are: filtration (HVL), focal 
spot size, kVp accuracy and reproducibility, mAs linearity, output waveforms, beam 
uniformity and alignment. The fluoroscopic system also requires visual and 
environmental inspection and performance testing. 
7.0. Records for Quality Improvement 
A quality program depends on good record keeping, therefore should be well 
documented, evaluated and updated. The following elements should be properly 
documented: Shielding calculations, inspections details and corrective actions. 
Record on occupational dose consists of:  
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- The nature of the work 
- Exposure from work for other facilities 
- Outcomes of health surveillance 
- Education and training of the workers 
- Results of exposure monitoring and dose assessments including results of 
investigation of abnormal exposure values. 
The member of staff should have access on the record of their own dose. Another 
important aspect of quality improvement is review which includes: policies and 
procedures, dose reports, inspections, repairs, audits, personnel consultations, unmet 
goals from previous years and non-compliance with maintenance. 
8.0. Pregnant Workers 
Ionizing radiation is one of the most agents that cause defects on embryo. Therefore the 
protection of pregnant workers needs a special consideration. Additional protection of the 
foetus should be considered immediately the pregnancy is known. On the other hand, 
pregnancy of a worker should not be a reason to perform procedures. A dosimeter placed 
inside the lead opron on the abdomen should be < 0.2 mSv/month. 
9.0. Emergency Plan and Procedures 
Emergency plan is an important component of a radiation safety program. It should help 
the personnel how to adequately identify, evacuate and react to emergency situations. The 
main goal is to protect the member of staff patient and public against potential accidents 
and it should include: plan of action, people involve in case of emergency (fire service, 
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police personnel, etc.) and placement of exit signs (such as illuminated warning signs for 
beam on/of, evacuation plan, location and use of fire extinguisher and pull station). 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
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APPENDIX 7: Typical Monte Carlo Input File 
c  
c ------------------------------------------------------------------------------ 
c --- Cells -------------------------------------------------------------------- 
c ------------------------------------------------------------------------------ 
c  
1 1 -2.3 -1 $ WALLB (CathLab_0 # WALLC) 
2 1 -2.3 -2 $ WALLC (CathLab_0 # WALLC) 
3 1 -2.3 -3 $ WALLA (CathLab_0 # WALLC) 
4 1 -2.3 -4 $ WALLD (CathLab_0 # WALLC) 
5 2 -7.874 -5 $ COUCH (CathLab_0 # WALLA) 
6 1 -2.3 (-6) $ floor (CathLab_0 # WALLC) 
7 1 -2.3 (-7) $ ceiling (CathLab_0 # WALLC) 
8 3 -0.001205 (-8) $ Dr1Space (CathLab_0 # WALLD) 
9 3 -0.001205 (-9 #10 #11 #12 #14 #5) $ XrSpace (CathLab_0 # WALLD) 
10 3 -0.001205 -10 $ source (CathLab_0 # WALLD) 
11 4 -11.35 (-11 (+12)) $ collimator (CathLab_0 # WALLB) 
12 5 -1.19 -13 $ Phantom (CathLab_0 # COUCH) 
13 4 -11.35 -14 $ Door (CathLab_0 # WALLB) 
14 4 -11.35 -15 $ Divide (CathLab_0 # WALLB) 
15 0 +17 $ Void 
c ------------------------------------------------------------------------------ 
c --- Surfaces ----------------------------------------------------------------- 
c ------------------------------------------------------------------------------  
1 rpp 0 45 0 830 0 300 $ WALLB (CathLab_0) 
2 rpp 45 490 0 45 0 300 $ WALLC (CathLab_0) 
3 rpp 445 490 165 785 0 300 $ WALLA (CathLab_0) 
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4 rpp 45 490 785 830 0 300 $ WALLD (CathLab_0) 
5 rpp 150 224 300 483 88.92 95 $ COUCH (CathLab_0) 
6 rpp 0 490 0 830 -50 0 $ FLOOR1 (CathLab_0) 
7 rpp 0 490 0 830 300 350 $ Ceiling1 (CathLab_0) 
8 rpp 445 485 45 165 0 300 $ 1_1 (CathLab_0) 
9 rpp 45 445 45 785 0 300 $ 4_1 (CathLab_0) 
10 s 200 370 30 0.01 $ source (CathLab_0) 
11 rpp 198 202 368 372 26.5 30.5 $ 5_1 (CathLab_0) 
12 rpp 199.92185 200.07815 369.094 370.094 29.594 30.5 $ 5_2 (CathLab_0) 
13 rcc 180 375 115 0 -15 9.184547654e-16 16 $ Phantom (CathLab_0) 
14 rpp 485 490 45 165 0 300 $ Door (CathLab_0) 
15 rpp 350 355 165 785 0 300 $ Divide (CathLab_0) 
17 rpp 0 490 0 830 -50 350 $ box around building  
c  
c ------------------------------------------------------------------------------ 
c --- Mode --------------------------------------------------------------------- 
c ------------------------------------------------------------------------------ 
c  
mode p 
c  
imp:p 1 13r 0 
c  
c ------------------------------------------------------------------------------ 
c --- Materials ---------------------------------------------------------------- 
c ------------------------------------------------------------------------------ 
c  
m1 $ Concrete (CathLab_0) 
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      1000   -0.0221 
      6000 -0.002484 
      8000  -0.57493 
     11000 -0.015208 
     12000 -0.001266 
     13000 -0.019953 
     14000 -0.304628 
     19000 -0.010045 
     20000 -0.042951 
     26000 -0.006435 
c  
m2 $ Steel (CathLab_0) 
     26000 +1 
c  
m3 $ Air (ct_room_accra) 
      6000 -0.000124 
      7000 -0.755268 
      8000 -0.231781 
     18000 -0.012827 
c  
m4 $ Lead (CT Gantry Accra) 
     82000 +1 
c 
m5 $ PMMA (PMMA_0deg) 
     1000 -0.080541 
     6000 -0.599846 
     8000 -0.319613  
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c ------------------------------------------------------------------------------ 
c --- Source ------------------------------------------------------------------- 
c ------------------------------------------------------------------------------ 
sdef par=p wgt=1 erg=D1 cel=10 x=200 y=370 z=30 rad=d2 
c ------------------------------------------------------------------------------ 
c --- Source Distributions ----------------------------------------------------- 
c ------------------------------------------------------------------------------ 
sc1 Point Source Distribution: # head 
si1 H  0.0005 0.0010 0.0015 0.0020 0.0025 
       0.0030 0.0035 0.0040 0.0045 0.0050 
       0.0055 0.0060 0.0065 0.0070 0.0075 
       0.0080 0.0085 0.0090 0.0095 0.0100 
       0.0105 0.0110 0.0115 0.0120 0.0125 
       0.0130 0.0135 0.0140 0.0145 0.0150 
       0.0155 0.0160 0.0165 0.0170 0.0175 
       0.0180 0.0185 0.0190 0.0195 0.0200 
       0.0205 0.0210 0.0215 0.0220 0.0225  
       0.0230 0.0235 0.0240 0.0245 0.0250  
       0.0255 0.0260 0.0265 0.0270 0.0275  
       0.0280 0.0285 0.0290 0.0295 0.0300 
       0.0305 0.0310 0.0315 0.0320 0.0325 
       0.0330 0.0335 0.0340 0.0345 0.0350 
       0.0355 0.0360 0.0365 0.0370 0.0375  
       0.0380 0.0385 0.0390 0.0395 0.0400 
       0.0405 0.0410 0.0415 0.0420 0.0425  
       0.0430 0.0435 0.0440 0.0445 0.0450  
       0.0455 0.0460 0.0465 0.0470 0.0475 
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       0.0480 0.0485 0.0490 0.0495 0.0500 
       0.0505 0.0510 0.0515 0.0520 0.0525  
       0.0530 0.0535 0.0540 0.0545 0.0550  
       0.0555 0.0560 0.0565 0.0570 0.0575  
       0.0580 0.0585 0.0590 0.0595 0.0600 
       0.0605 0.0610 0.0615 0.0620 0.0625 
       0.0630 0.0635 0.0640 0.0645 0.0650  
       0.0655 0.0660 0.0665 0.0670 0.0675  
       0.0680 0.0685 0.0690 0.0695 0.0700 
       0.0705 0.0710 0.0715 0.0720 0.0725  
       0.0730 0.0735 0.0740 0.0745 0.0750  
       0.0755 0.0760 0.0765 0.0770 0.0775  
       0.0780 0.0785 0.0790 0.0795 0.0800 
       0.0805 0.0810 0.0815 0.0820 0.0825  
       0.0830 0.0835 0.0840 0.0845 0.0850  
       0.0855 0.0860 0.0865 0.0870 0.0875  
       0.0880 0.0885 0.0890 0.0895 0.0900 
       0.0905 0.0910 0.0915 0.0920 0.0925  
       0.0930 0.0935 0.0940 0.0945 0.0950  
       0.0955 0.0960 0.0965 0.0970 0.0975  
       0.0980 0.0985 0.0990 0.0995 0.1000 
sp1 D  0            0            0           0            0 
       0            0            0           0            0 
       0            0            0           0            0 
       0            0            0           0            2.56162E-08 
       1.47956E-07  9.30689E-07  3.8289E-06  1.58249E-05  4.52987E-05 
       0.000129956  0.000296961  0.000684586 0.001280192  0.002409286 
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       0.003937936  0.006475987  0.009475574 0.013922641  0.01875253 
       0.025350137  0.032254988  0.041145166 0.049918449  0.060709287 
       0.071005743  0.083179034  0.094405477 0.10732336   0.119009585 
       0.132093088  0.14366044   0.1564176   0.166925401  0.178242096 
       0.188618685  0.19976588   0.208933707 0.218600813  0.226728106 
       0.235389214  0.242225636  0.249402647 0.254675851  0.260193097 
       0.264697476  0.269314622  0.27281472  0.276475796  0.279061166 
       0.28168915   0.283381798  0.285188167 0.286007238  0.286834259 
       0.286851368  0.286957138  0.286563567 0.286166816  0.28525584 
       0.284425957  0.282974298  0.28151876  0.279744891  0.278050208 
       0.276053731  0.274055474  0.271696464 0.269417085  0.266906257 
       0.264398863  0.261714146  0.259108486 0.256298346  0.253495901 
       0.250630553  0.24784261   0.244876198 0.241920344  0.238826665 
       0.235811724  0.232818918  0.22983756  0.226726516  0.223691478 
       0.220607656  0.217538782  0.214439377 0.211413434  0.208407462 
       0.2054158    0.202395708  0.199445324 0.196459959  0.193490113 
       0.190496098  0.187620892  0.184663766 0.181773169  0.178946809 
       0.653478728  0.17337035   0.17057293  1            0.165048115 
       0.162332933  0.159632506  0.156990148 0.154404205  0.151768844 
       0.14914792   0.146632385  0.144169386 0.141627201  0.139099073 
       0.136670483  0.134292075  0.131880402 0.404127408  0.127122886 
       0.124813486  0.122522786  0.191832891 0.117964345  0.104517736 
       0.102758686  0.1010011    0.099250447 0.097531022  0.095837356 
       0.09414369   0.092442074  0.090769842 0.089085717  0.087402609 
       0.085709961  0.084046951  0.082394245 0.080742748  0.07911949 
       0.077523644  0.075877362  0.074233242 0.072617807  0.07103023 
       0.069421982  0.067815452  0.066252425 0.064715793  0.063126988 
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       0.061539926  0.059960026  0.058407913 0.056840066  0.055273821 
       0.053732228  0.052217221  0.050660936 0.049105942  0.04757569 
       0.046071705  0.044499297  0.042929211 0.041400911  0.039898764 
       0.03831653   0.036736457  0.035195094 0.033680265  0.032072774 
       0.030467407  0.028889796  0.027340291 0.025594236  0.023849142 
       0.022126359  0.020434493  0.018722052 0.017012053  0.015332774 
       0.013683909  0.010210753  0.006742792 0.003340765  0 
si2 h  0 0.01       $ inner and outer radii of sphere  
sp2 d  0 1          $ sampling range 
c ------------------------------------------------------------------------------ 
c --- Mesh Tally $ units (sieverts/h/source_particle) and MeV/cm3/particle------ 
c ------------------------------------------------------------------------------ 
TMESH 
RMESH1:p DOSE 30 1 2 1.0 
    CORA1 45 6i 445 
    CORB1 45 9i 785 
    CORC1 0 10i 300 
ENDMD  
c ------------------------------------------------------------------------------ 
c --- Control ------------------------------------------------------------------ 
c ------------------------------------------------------------------------------ 
stop nps=1900000000 
prdmp j -60 1 1 100000 
 
 
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APPENDIX 8: Raw Data of the Simulation Results 
1. Distribution for the tube position AP 0° at different height Z 
 
x y Z Value/Sv/h/particles error 
45 45 85.7143 9.61E-20 0.5383 
102.143 45 85.7143 8.01E-17 0.0197 
159.286 45 85.7143 1.14E-16 0.0158 
216.429 45 85.7143 1.37E-16 0.0141 
273.571 45 85.7143 1.25E-16 0.015 
330.714 45 85.7143 9.45E-17 0.0177 
387.857 45 85.7143 6.03E-17 0.0226 
45 119 85.7143 3.27E-17 0.0309 
102.143 119 85.7143 1.18E-16 0.0156 
159.286 119 85.7143 1.91E-16 0.0121 
216.429 119 85.7143 2.65E-16 0.0102 
273.571 119 85.7143 2.27E-16 0.0111 
330.714 119 85.7143 1.42E-16 0.0141 
387.857 119 85.7143 6.25E-17 0.0201 
45 193 85.7143 2.70E-17 0.029 
102.143 193 85.7143 1.51E-16 0.014 
159.286 193 85.7143 2.88E-16 0.01 
216.429 193 85.7143 2.01E-14 0.001 
273.571 193 85.7143 4.66E-16 0.0078 
330.714 193 85.7143 1.85E-16 0.0125 
387.857 193 85.7143 4.22E-17 0.0197 
45 267 85.7143 8.64E-18 0.0512 
102.143 267 85.7143 1.71E-16 0.0132 
159.286 267 85.7143 3.12E-16 0.0093 
216.429 267 85.7143 5.47E-14 0.0005 
273.571 267 85.7143 7.69E-16 0.0056 
330.714 267 85.7143 2.29E-16 0.0112 
387.857 267 85.7143 4.43E-17 0.0188 
45 341 85.7143 1.18E-18 0.1606 
102.143 341 85.7143 1.54E-16 0.0142 
159.286 341 85.7143 2.43E-16 0.0102 
216.429 341 85.7143 2.93E-14 0.0003 
273.571 341 85.7143 6.70E-16 0.0056 
330.714 341 85.7143 2.09E-16 0.0116 
387.857 341 85.7143 3.96E-17 0.0197 
45 415 85.7143 6.48E-19 0.2517 
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102.143 415 85.7143 1.03E-16 0.0179 
159.286 415 85.7143 1.14E-16 0.016 
216.429 415 85.7143 5.71E-17 0.0158 
273.571 415 85.7143 1.78E-16 0.0129 
330.714 415 85.7143 1.26E-16 0.016 
387.857 415 85.7143 2.92E-17 0.0244 
45 489 85.7143 3.32E-19 0.3781 
102.143 489 85.7143 6.38E-17 0.0231 
159.286 489 85.7143 6.91E-17 0.0221 
216.429 489 85.7143 6.68E-17 0.0232 
273.571 489 85.7143 7.76E-17 0.0209 
330.714 489 85.7143 7.29E-17 0.0223 
387.857 489 85.7143 1.94E-17 0.0331 
45 563 85.7143 1.42E-19 0.4149 
102.143 563 85.7143 3.93E-17 0.0303 
159.286 563 85.7143 4.45E-17 0.0294 
216.429 563 85.7143 4.68E-17 0.0285 
273.571 563 85.7143 4.62E-17 0.0289 
330.714 563 85.7143 4.59E-17 0.0291 
387.857 563 85.7143 1.31E-17 0.042 
45 637 85.7143 1.05E-19 0.4706 
102.143 637 85.7143 2.80E-17 0.036 
159.286 637 85.7143 2.95E-17 0.0367 
216.429 637 85.7143 3.20E-17 0.0353 
273.571 637 85.7143 2.99E-17 0.0361 
330.714 637 85.7143 3.02E-17 0.0357 
387.857 637 85.7143 8.94E-18 0.0543 
45 711 85.7143 2.94E-20 0.5214 
102.143 711 85.7143 2.14E-17 0.0432 
159.286 711 85.7143 2.07E-17 0.0439 
216.429 711 85.7143 2.21E-17 0.0422 
273.571 711 85.7143 2.21E-17 0.0423 
330.714 711 85.7143 2.35E-17 0.0423 
387.857 711 85.7143 6.42E-18 0.0659 
45 45 107.143 5.75E-20 0.4758 
102.143 45 107.143 8.83E-17 0.0179 
159.286 45 107.143 1.41E-16 0.0139 
216.429 45 107.143 1.79E-16 0.0121 
273.571 45 107.143 1.60E-16 0.0131 
330.714 45 107.143 1.04E-16 0.0163 
387.857 45 107.143 6.16E-17 0.0216 
45 119 107.143 3.19E-17 0.0295 
102.143 119 107.143 1.31E-16 0.0145 
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159.286 119 107.143 2.32E-16 0.0109 
216.429 119 107.143 4.41E-16 0.0072 
273.571 119 107.143 2.96E-16 0.0094 
330.714 119 107.143 1.59E-16 0.013 
387.857 119 107.143 6.46E-17 0.0191 
45 193 107.143 3.05E-17 0.0283 
102.143 193 107.143 1.53E-16 0.0135 
159.286 193 107.143 3.05E-16 0.0093 
216.429 193 107.143 5.20E-14 0.0007 
273.571 193 107.143 5.70E-16 0.0068 
330.714 193 107.143 2.00E-16 0.0117 
387.857 193 107.143 4.57E-17 0.019 
45 267 107.143 8.82E-18 0.0516 
102.143 267 107.143 1.55E-16 0.0133 
159.286 267 107.143 1.71E-16 0.0122 
216.429 267 107.143 3.79E-15 0.0015 
273.571 267 107.143 4.59E-16 0.007 
330.714 267 107.143 2.26E-16 0.0106 
387.857 267 107.143 4.51E-17 0.0185 
45 341 107.143 7.99E-19 0.1719 
102.143 341 107.143 1.31E-16 0.0142 
159.286 341 107.143 1.14E-16 0.0148 
216.429 341 107.143 5.77E-17 0.022 
273.571 341 107.143 3.55E-16 0.0076 
330.714 341 107.143 1.98E-16 0.0113 
387.857 341 107.143 3.95E-17 0.0202 
45 415 107.143 3.22E-19 0.2776 
102.143 415 107.143 9.16E-17 0.018 
159.286 415 107.143 6.40E-17 0.0204 
216.429 415 107.143 3.27E-17 0.0325 
273.571 415 107.143 1.22E-16 0.0146 
330.714 415 107.143 1.16E-16 0.0155 
387.857 415 107.143 2.94E-17 0.025 
45 489 107.143 1.27E-19 0.3534 
102.143 489 107.143 5.49E-17 0.0241 
159.286 489 107.143 4.22E-17 0.0266 
216.429 489 107.143 3.35E-17 0.0293 
273.571 489 107.143 6.07E-17 0.0224 
330.714 489 107.143 6.76E-17 0.0221 
387.857 489 107.143 1.80E-17 0.0344 
45 563 107.143 2.18E-19 0.3932 
102.143 563 107.143 3.65E-17 0.0309 
159.286 563 107.143 3.53E-17 0.0308 
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216.429 563 107.143 3.77E-17 0.0299 
273.571 563 107.143 3.93E-17 0.0294 
330.714 563 107.143 4.24E-17 0.0288 
387.857 563 107.143 1.31E-17 0.0428 
45 637 107.143 1.47E-19 0.5278 
102.143 637 107.143 2.80E-17 0.0366 
159.286 637 107.143 2.58E-17 0.0369 
216.429 637 107.143 2.79E-17 0.0367 
273.571 637 107.143 2.65E-17 0.0362 
330.714 637 107.143 2.92E-17 0.0366 
387.857 637 107.143 8.30E-18 0.0549 
45 711 107.143 6.45E-20 0.4556 
102.143 711 107.143 1.94E-17 0.0447 
159.286 711 107.143 2.04E-17 0.0436 
216.429 711 107.143 2.10E-17 0.0423 
273.571 711 107.143 2.17E-17 0.0423 
330.714 711 107.143 2.06E-17 0.0431 
387.857 711 107.143 6.92E-18 0.0674 
45 45 150 1.05E-19 0.5779 
102.143 45 150 1.11E-16 0.0157 
159.286 45 150 2.20E-16 0.0107 
216.429 45 150 5.90E-16 0.0053 
273.571 45 150 3.26E-16 0.0083 
330.714 45 150 1.43E-16 0.0136 
387.857 45 150 7.81E-17 0.0191 
45 119 150 3.79E-17 0.0277 
102.143 119 150 1.55E-16 0.0132 
159.286 119 150 3.29E-16 0.0088 
216.429 119 150 3.25E-14 0.0009 
273.571 119 150 4.10E-15 0.0024 
330.714 119 150 2.02E-16 0.0113 
387.857 119 150 8.01E-17 0.0175 
45 193 150 3.34E-17 0.0282 
102.143 193 150 1.33E-16 0.0141 
159.286 193 150 2.14E-16 0.0109 
216.429 193 150 1.63E-14 0.0011 
273.571 193 150 1.98E-15 0.0032 
330.714 193 150 2.11E-16 0.0108 
387.857 193 150 4.72E-17 0.0185 
45 267 150 8.45E-18 0.0549 
102.143 267 150 1.14E-16 0.0152 
159.286 267 150 1.05E-16 0.0167 
216.429 267 150 1.35E-16 0.0147 
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273.571 267 150 2.29E-16 0.0101 
330.714 267 150 2.14E-16 0.0103 
387.857 267 150 4.61E-17 0.0188 
45 341 150 9.36E-19 0.1539 
102.143 341 150 8.66E-17 0.0176 
159.286 341 150 6.27E-17 0.0222 
216.429 341 150 6.37E-17 0.0229 
273.571 341 150 1.62E-16 0.0118 
330.714 341 150 1.73E-16 0.0113 
387.857 341 150 3.70E-17 0.0212 
45 415 150 2.19E-19 0.3128 
102.143 415 150 5.92E-17 0.022 
159.286 415 150 4.08E-17 0.0288 
216.429 415 150 3.94E-17 0.0292 
273.571 415 150 7.43E-17 0.019 
330.714 415 150 9.93E-17 0.0158 
387.857 415 150 2.61E-17 0.0263 
45 489 150 2.04E-19 0.3276 
102.143 489 150 3.79E-17 0.0283 
159.286 489 150 2.77E-17 0.0346 
216.429 489 150 2.79E-17 0.0352 
273.571 489 150 3.85E-17 0.0279 
330.714 489 150 5.44E-17 0.0225 
387.857 489 150 1.68E-17 0.0351 
45 563 150 4.65E-20 0.6719 
102.143 563 150 2.74E-17 0.0351 
159.286 563 150 2.09E-17 0.0396 
216.429 563 150 2.13E-17 0.0389 
273.571 563 150 2.60E-17 0.0349 
330.714 563 150 3.66E-17 0.0294 
387.857 563 150 1.07E-17 0.0453 
45 637 150 3.37E-20 0.5678 
102.143 637 150 2.10E-17 0.0399 
159.286 637 150 2.00E-17 0.0406 
216.429 637 150 2.13E-17 0.0397 
273.571 637 150 2.39E-17 0.0387 
330.714 637 150 2.49E-17 0.0367 
387.857 637 150 7.85E-18 0.0551 
45 711 150 7.89E-20 0.7259 
102.143 711 150 1.58E-17 0.0463 
159.286 711 150 1.70E-17 0.0459 
216.429 711 150 1.79E-17 0.0448 
273.571 711 150 1.99E-17 0.0429 
 137   
 
University of Ghana  http://ugspace.ug.edu.gh
330.714 711 150 1.92E-17 0.0435 
387.857 711 150 6.80E-18 0.0663 
45 45 171.429 2.05E-20 0.5354 
102.143 45 171.429 1.24E-16 0.0149 
159.286 45 171.429 2.85E-16 0.0093 
216.429 45 171.429 9.82E-15 0.0016 
273.571 45 171.429 2.20E-15 0.0033 
330.714 45 171.429 1.70E-16 0.0124 
387.857 45 171.429 8.52E-17 0.0182 
45 119 171.429 4.09E-17 0.0272 
102.143 119 171.429 1.61E-16 0.013 
159.286 119 171.429 3.59E-16 0.0084 
216.429 119 171.429 3.46E-14 0.0008 
273.571 119 171.429 6.72E-15 0.0019 
330.714 119 171.429 2.18E-16 0.0109 
387.857 119 171.429 8.18E-17 0.0176 
45 193 171.429 3.59E-17 0.0288 
102.143 193 171.429 1.18E-16 0.0154 
159.286 193 171.429 1.61E-16 0.013 
216.429 193 171.429 1.34E-15 0.0028 
273.571 193 171.429 4.15E-16 0.0066 
330.714 193 171.429 2.11E-16 0.0107 
387.857 193 171.429 4.78E-17 0.0187 
45 267 171.429 8.92E-18 0.0563 
102.143 267 171.429 9.32E-17 0.0176 
159.286 267 171.429 9.80E-17 0.0175 
216.429 267 171.429 1.14E-16 0.016 
273.571 267 171.429 1.62E-16 0.0125 
330.714 267 171.429 2.11E-16 0.0103 
387.857 267 171.429 4.40E-17 0.0191 
45 341 171.429 1.19E-18 0.1427 
102.143 341 171.429 6.75E-17 0.0207 
159.286 341 171.429 6.03E-17 0.0234 
216.429 341 171.429 6.17E-17 0.023 
273.571 341 171.429 1.08E-16 0.0151 
330.714 341 171.429 1.64E-16 0.0114 
387.857 341 171.429 3.49E-17 0.0221 
45 415 171.429 4.55E-19 0.268 
102.143 415 171.429 4.77E-17 0.0251 
159.286 415 171.429 3.78E-17 0.0295 
216.429 415 171.429 3.79E-17 0.0299 
273.571 415 171.429 5.59E-17 0.0224 
330.714 415 171.429 9.36E-17 0.0161 
 138   
 
University of Ghana  http://ugspace.ug.edu.gh
387.857 415 171.429 2.42E-17 0.0274 
45 489 171.429 1.19E-19 0.328 
102.143 489 171.429 3.16E-17 0.0319 
159.286 489 171.429 2.63E-17 0.0356 
216.429 489 171.429 2.58E-17 0.036 
273.571 489 171.429 3.33E-17 0.0313 
330.714 489 171.429 5.08E-17 0.0231 
387.857 489 171.429 1.70E-17 0.0353 
45 563 171.429 7.93E-20 0.4561 
102.143 563 171.429 2.14E-17 0.0385 
159.286 563 171.429 1.87E-17 0.0423 
216.429 563 171.429 1.92E-17 0.0419 
273.571 563 171.429 2.24E-17 0.0388 
330.714 563 171.429 3.38E-17 0.0301 
387.857 563 171.429 1.07E-17 0.0457 
45 637 171.429 6.79E-20 0.6706 
102.143 637 171.429 1.80E-17 0.0429 
159.286 637 171.429 1.55E-17 0.0461 
216.429 637 171.429 1.74E-17 0.0431 
273.571 637 171.429 1.96E-17 0.0425 
330.714 637 171.429 2.35E-17 0.038 
387.857 637 171.429 8.14E-18 0.0562 
45 711 171.429 5.62E-21 1 
102.143 711 171.429 1.60E-17 0.0476 
159.286 711 171.429 1.54E-17 0.0463 
216.429 711 171.429 1.62E-17 0.0476 
273.571 711 171.429 1.64E-17 0.0465 
330.714 711 171.429 1.77E-17 0.0453 
387.857 711 171.429 6.17E-18 0.0668 
 
2. Distribution at the tube position LAO 30° at 163.6 cm from the floor 
X Y Value /Sv/h/particle 
45 45 1.30E-25 
102.143 45 3.90E-20 
159.286 45 2.49E-20 
216.429 45 2.56E-20 
273.571 45 3.01E-20 
330.714 45 6.84E-21 
387.857 45 3.61E-24 
45 119 1.40E-24 
102.143 119 1.09E-19 
 139   
 
University of Ghana  http://ugspace.ug.edu.gh
159.286 119 7.24E-20 
216.429 119 6.89E-20 
273.571 119 6.06E-20 
330.714 119 1.16E-20 
387.857 119 8.20E-24 
45 193 1.70E-24 
102.143 193 4.67E-19 
159.286 193 2.72E-20 
216.429 193 8.99E-21 
273.571 193 1.38E-20 
330.714 193 1.39E-20 
387.857 193 3.85E-21 
45 267 1.20E-24 
102.143 267 1.38E-18 
159.286 267 1.70E-20 
216.429 267 9.52E-21 
273.571 267 5.70E-20 
330.714 267 3.41E-20 
387.857 267 8.93E-21 
45 341 8.80E-24 
102.143 341 1.77E-18 
159.286 341 3.61E-20 
216.429 341 1.24E-20 
273.571 341 7.74E-20 
330.714 341 4.93E-20 
387.857 341 5.76E-21 
45 415 3.70E-24 
102.143 415 1.17E-18 
159.286 415 3.46E-20 
216.429 415 2.39E-20 
273.571 415 4.81E-20 
330.714 415 3.97E-20 
387.857 415 2.13E-21 
45 489 9.10E-24 
102.143 489 3.25E-19 
159.286 489 2.31E-20 
216.429 489 4.54E-21 
273.571 489 1.26E-20 
330.714 489 2.44E-20 
387.857 489 8.62E-21 
45 563 7.80E-23 
102.143 563 4.97E-20 
159.286 563 8.70E-22 
 140   
 
University of Ghana  http://ugspace.ug.edu.gh
216.429 563 2.67E-20 
273.571 563 4.49E-21 
330.714 563 1.80E-20 
387.857 563 2.24E-21 
45 637 5.50E-24 
102.143 637 2.72E-20 
159.286 637 1.82E-20 
216.429 637 1.49E-20 
273.571 637 6.78E-21 
330.714 637 1.55E-20 
387.857 637 5.50E-24 
45 711 4.30E-23 
102.143 711 1.53E-20 
159.286 711 8.44E-21 
216.429 711 2.20E-21 
273.571 711 1.50E-24 
330.714 711 3.50E-21 
387.857 711 6.29E-22 
 
 
3. Distribution at the tube position RAO 30° at 171 cm from the floor 
 
X Y Value /Sv/h/particle 
45 45 2.55E-18 
102.143 45 2.80E-16 
159.286 45 3.60E-16 
216.429 45 4.56E-16 
273.571 45 5.69E-16 
330.714 45 6.60E-16 
387.857 45 5.69E-16 
45 119 2.30E-16 
102.143 119 3.53E-16 
159.286 119 4.83E-16 
216.429 119 6.73E-16 
273.571 119 9.39E-16 
330.714 119 3.11E-15 
387.857 119 3.80E-15 
45 193 1.51E-16 
102.143 193 4.06E-16 
159.286 193 5.42E-16 
216.429 193 8.32E-16 
273.571 193 1.59E-14 
 141   
 
University of Ghana  http://ugspace.ug.edu.gh
330.714 193 6.78E-14 
387.857 193 2.09E-14 
45 267 7.77E-17 
102.143 267 4.83E-16 
159.286 267 6.65E-16 
216.429 267 1.15E-15 
273.571 267 3.21E-14 
330.714 267 1.05E-13 
387.857 267 2.80E-14 
45 341 3.36E-17 
102.143 341 5.09E-16 
159.286 341 7.15E-16 
216.429 341 1.29E-15 
273.571 341 3.72E-14 
330.714 341 1.18E-13 
387.857 341 3.09E-14 
45 415 1.57E-17 
102.143 415 4.56E-16 
159.286 415 6.22E-16 
216.429 415 1.07E-15 
273.571 415 2.97E-14 
330.714 415 9.83E-14 
387.857 415 2.66E-14 
45 489 9.18E-18 
102.143 489 3.68E-16 
159.286 489 4.75E-16 
216.429 489 7.19E-16 
273.571 489 1.07E-14 
330.714 489 5.14E-14 
387.857 489 1.85E-14 
45 563 5.10E-18 
102.143 563 2.69E-16 
159.286 563 3.38E-16 
216.429 563 4.63E-16 
273.571 563 6.92E-16 
330.714 563 1.01E-15 
387.857 563 8.36E-16 
45 637 3.51E-18 
102.143 637 2.10E-16 
159.286 637 2.59E-16 
216.429 637 3.31E-16 
273.571 637 4.20E-16 
330.714 637 4.91E-16 
 142   
 
University of Ghana  http://ugspace.ug.edu.gh
387.857 637 1.60E-16  
45 711 2.60E-18 
102.143 711 1.70E-16 
159.286 711 2.03E-16 
216.429 711 2.39E-16 
273.571 711 2.75E-16 
330.714 711 2.99E-16 
387.857 711 9.56E-17 
 
 143