Department of Nuclear Safety and Security

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    Assessment Of Radiation Dose Reduction To Patients During Barium Series Fluoroscopy Procedures
    (University of Ghana, 2020-07) Rwagatare, E.
    The current reference dose and dose reduction techniques have been assessed during barium series procedures at the Greater Accra Regional Hospital. The study used the kerma area product (KAP) meter fitted on the collimator of the GE fluoroscopy machine to estimate entrance surface doses of patients. The study focused on 120 patients undergoing barium swallow, barium enema and barium meal procedures. This was because previous studies in this area have proposed further dose optimization in barium enema procedure in particular. The self-consistent performance of the fluoroscopy machine was checked using the Piranha and Ocean quality control kit prior to data collection. Patient demographics (such as height, weight and age) and examination parameters (such as tube voltage, screening time, number of radiographs taken and beam projection angle) were collected for the estimation of organ doses using the PCXMC, a computational Monte Carlo based program. The mean KAP readings for barium swallow, barium meal and barium enema examination were 42.01, 4.56 and 9.53 mGy.cm2 respectively. The patient effective dose for barium swallow, barium meal and barium enema examinations were 1.55, 1.94 and 0.43 mSv respectively. The breast (4.72 mGy), stomach (3.54 mGy) and gonads (0.95 mGy) received the highest dose for barium swallow, barium meal and barium enema examinations respectively. Barium swallow was found not to be optimized when the KAP values of this study were compared with previous studies. Further analysis on barium swallow examinations revealed that number of radiographs taken and screening time influences the KAP values. Also, body mass index and KAP values influences the organ doses. Therefore, a relationship between number of radiographs taken, screening time, body mass index and KAP readings was proposed for implementation at the Hospital to enhance dose reduction. Further studies into other factors influencing patient doses is recommended to enhance patient dose optimization at the hospital.
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    Development Of National Indication-Based Diagnostic Reference Levels And Optimisation Methods For Computed Tomography Examinations In Ghana
    (University of Ghana., 2020-07) Botwe, B.
    ABSTRACT Background: Diagnostic reference levels (DRLs) and dose optimisation methods are crucial for effective radiation dose management. Countries utilising ionising radiation for medical purposes are required to develop and implement them, taking into consideration their clinical situations, infrastructure, population characteristics as well as social, technical and economic factors. However, in Ghana, there is no established national indication-based DRL. Main Objective: The main objective of this study was to develop national indication-based DRL values for common and prioritised indications of the adult human body for clinical application in Ghana. It was also to assess the risk of undertaking each indication-based CT examination, and also propose some steps for dose optimisation. Materials and Methods: The methodological approach recommended by the International Commission for Radiological Protection (ICRP), publication 135, for the development of DRLs, was employed. Studies on CT infrastructure and common indications as well as quality management systems (QMS) were conducted. Quality control (QC) tests were undertaken using a CT dose profiler, barracuda set, uniform water phantom and an ImageQC software v.1.43. Radiologists were mainly requested to define the basic diagnostic requirement of each indication. Dose descriptors such as volume weighted CT dose index (CTDIvol) and dose length product (DLP) of reported CT scans were retrieved from the picture archiving and communication system (PACS) of scanners, constituting 71.4% of the total CT scanners in Ghana. Overall, 3,960 data sets were collected for all the common and prioritised indications which included: cerebrovascular accident (CVA) or stroke, head trauma/injury, brain tumour/space occupying lesion (SOL), lung tumour/cancer, chest lesion with chronic kidney disease, abdominopelvic lesion, kidney stone, urothelial malignancy/CT intravenous urography (CT-IVU) and pulmonary embolism (PE). ImageJ software version 1.52 was used to analyse the objective image qualities. Statistical Package for the Social Sciences (SPSS) version 23.0 was used to extract the DRL values for the common indications in CT examinations. Microsoft excel version 2013 was used to pictorially project the results and also develop a tool (BOTB) for dose monitoring. Lifetime Attributable Risk (LAR) of cancer incidence and mortality were estimated for various organs using a Monte Carlo-based software (National Cancer Institute Dosimetry System CT software version 2.1) and the Biological Effects of Ionising Radiation (BEIR) VII model. An anthropomorphic Alderson RANDO phantom and patients’ clinical data were used to explore an optimisation method for cerebrovascular accident (CVA) imaging. Regression analyses were further used to model equations for organ doses in CVA imaging. CT phantom PBU-60 was also used to evaluate automatic exposure control (AEC) dose impact in facilities operating without AEC systems. In all inferential analyses, a p-value of ≤ 0.05 was used to interpret the findings as statistically significant. Main Results: The various indications and their respective projected DRL values in terms of CTDIvol (mGy) and DLP (mGy.cm) were CVA/stroke (77 mGy; 1313 mGy.cm), head trauma/injury (76 mGy; 1596 mGy.cm), brain tumour/SOL (77 mGy; 2696 mGy.cm), lung tumour/cancer (12 mGy; 828 mGy.cm) and chest lesion with chronic kidney disease (13 mGy; 467 mGy.cm). Others were abdominopelvic lesion (17 mGy; 1299 mGy.cm), kidney stone (15 mGy; 731 mGy.cm), urothelial malignancy/CT-IVU (11 mGy; 1449 mGy.cm) and pulmonary embolism (14 mGy; 942 mGy.cm). The risk of PE radiation-induced breast cancer ranged from 6-115.8 people in 100,000 procedures. Moreover, CT-IVU radiation-induced colon cancer risks ranged from 53.3-66.4 people in 100,000 procedures. About 1 in 38,462 to 1 in 14,706 patients were also likely to develop ovarian cancer due to CT-IVU examinations in Ghana. A novel examination protocol was further developed in the study that could be used to scan CVA related conditions with optimal image quality, while reducing the mean effective dose of the facilities by 23.8%, and organ doses by 32% (lens), 70.7% (spinal cord), 57.2% (thyroid) and 75.6% (oral cavity). Moreover, eight organ dose equations were developed to aid in dose management. Finally, if AEC are used in facilities operating without such systems, radiation dose levels could also be reduced by a range of 46.4-58.3% without any significant compromise on image quality. Conclusion: The projected indication-based DRL values and optimisation methods could be used to manage CT radiation dose in Ghana.
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    Assessment of Radiation Dose Reduction to Patients during Barium Series Fluoroscopy Procedures
    (University Of Ghana, 2020-07) Rwagatare, E.
    The current reference dose and dose reduction techniques have been assessed during barium series procedures at the Greater Accra Regional Hospital. The study used the kerma area product (KAP) meter fitted on the collimator of the GE fluoroscopy machine to estimate entrance surface doses of patients. The study focused on 120 patients undergoing barium swallow, barium enema and barium meal procedures. This was because previous studies in this area have proposed further dose optimization in barium enema procedure in particular. The self-consistent performance of the fluoroscopy machine was checked using the Piranha and Ocean quality control kit prior to data collection. Patient demographics (such as height, weight and age) and examination parameters (such as tube voltage, screening time, number of radiographs taken and beam projection angle) were collected for the estimation of organ doses using the PCXMC, a computational Monte Carlo based program. The mean KAP readings for barium swallow, barium meal and barium enema examination were 42.01, 4.56 and 9.53 mGy.cm2 respectively. The patient effective dose for barium swallow, barium meal and barium enema examinations were 1.55, 1.94 and 0.43 mSv respectively. The breast (4.72 mGy), stomach (3.54 mGy) and gonads (0.95 mGy) received the highest dose for barium swallow, barium meal and barium enema examinations respectively. Barium swallow was found not to be optimized when the KAP values of this study were compared with previous studies. Further analysis on barium swallow examinations revealed that number of radiographs taken and screening time influences the KAP values. Also, body mass index and KAP values influences the organ doses. Therefore, a relationship between number of radiographs taken, screening time, body mass index and KAP readings was proposed for implementation at the Hospital to enhance dose reduction. Further studies into other factors influencing patient doses is recommended to enhance patient dose optimization at the hospital
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    Determination of Level of Radio Frequency Field Exposure to Military Personnel from Tactical Field Expedient Antennas
    (University of Ghana, 2019-07) Asamoah, J.B.
    Radio communication is an integral part of any military operation. This helps commanders at all levels to achieve command and control in their operational environment. The employment of these radios with their corresponding antennas has led to an increase in the concern of the potential health risks that may arise as a result of exposure to radio frequency (RF) radiations. The main objective of this research was to determine the levels of radio frequency field exposure to military personnel from tactical expedient antennas. The electric field strength and Specific Absorption Rate (SAR) of selected military radio antenna were measured at various distances from radio antennas locations in the Burma Camp barracks and analysed during real-time transmission. The radios antennas were selected based on their employment in the field of operations: base station, manpack vehicle mount and handheld (SAR).
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    Re-Assessment of Radiological Hazards of Naturally Occurring Radioactive Materials (Norm) from the Jubilee Oilfields of Ghana
    (University of Ghana, 2018-07) Nyarko, B.E.
    This study re-assesses the radiological hazards of Naturally Occurring Radioactive Materials (NORM) on workers and the general public due to continuous exploration and production of crude oil and waste generated from the Jubilee Oilfields of Ghana. The specific activities of 234U, 238U, 230Th, 232Th, 226Ra, 210Pb, 234Th, 228Ra, 224Ra and 40K in crude oil and NORM waste samples have been estimated using Sodium Iodide detector and alpha spectrometry after radiochemical separation. A trend analysis of an increase in the activity concentrations of radionuclides has also been established between the previous study and this study using a statistical test of association (paired t-test) at 95% confidence interval. An annual effective dose of 1.32 mSv obtained for occupationally exposed workers in this study was below the International Commission on Radiological Protection (ICRP) recommended dose limit of 20 mSv per year (averaged over 5 years and not exceeding 50 mSv per year in any single year). From the study, radium concentrations are of radiological importance for sludge and produced water due to the high levels of activity concentrations recorded. There is also tendency for possible increase levels of activity concentration of these radionuclides with time as exploration and production continues with more wells being drilled. As a result it is recommended that a national guideline for monitoring of NORM is established to ensure regulatory monitoring of these facilities in Ghana.
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    The Evaluation Of The Performance Of The Automatic Exposure Control System Of Some Selected Mammography Facilities In The Greater Accra Region, Ghana
    (University of Ghana, 2013-07) Amesimenu, R.
    Mammography aids in the early detection of breast cancer. X-rays has an associated risk of inducing cancer though very useful and as such mammography procedures should be optimized through the appropriate processes such as the selection of exposure factors for an optimum image and minimal dose to patients. The automatic exposure control (AEC) aids in the selection of exposure factors thus controlling the amount of radiation to the breast and automatically compensates for differences in breast thickness and density. The performance of the automatic exposure control system of mammography equipment and the status of quality management systems including quality assurance and quality controls of four (4) mammography facilities within the Greater Accra Region were assessed. In assessing the performance of the automatic exposure control system, the short term reproducibility test, thickness and voltage compensation tests were carried out using breast equivalent phantom of various thicknesses. Half value layer test, film reject analysis and patient dose assessment were also performed. Analysis of the responses of the questionnaire administered to radiographers and supervisors of the selected facilities revealed that three (3) of the facilities have some aspect of a quality management system programme in place but not effectively implemented. Measured optical densities from the various tests performed to evaluate the performance of the automatic exposure control systems revealed that the AEC compensates for the different phantom thicknesses and tube voltages (kV) by producing comparable optical densities for the various phantom thicknesses and tube voltages. Some of the measured optical densities were within the recommended optical density range of 1.5 OD – 1.9 OD. The highest optical density value was 0.13 OD above the highest limit of 1.9 OD. The film reject analysis showed that patient motion accounted for the larger part (28 %) of film rejects. Other factors such as too light or too dark films also accounted for film reject signifying the need for continuous training for radiographers and an effective quality control programme. Estimated mean glandular dose (MGD) of values 1.0 mGy, 1.3 mGy, 1.1 mGy and 1.1 mGy at 28 kV for the selected facilities were less than 2 mGy and 3 mGy per the recommendation of International Atomic Energy Agency (IAEA) and American College of Radiology (ACR) respectively. Management of mammography facilities must establish an effective quality management system which must be implemented and continually improved to enhance radiological services delivered to patients as well as improve the radiation protection of patients.
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    Computational Hydrodynamic Modelling Of The Fate And Impact Of Natural Radionuclides In Liquid Effluent Discharges From The Gold Processing Plant At Aboso Goldmines In Damang Tarkwa, Ghana
    (University of Ghana, 2013-07) Owusu, S.
    Transport of radioactivity in surface water of mine-origin can occur either due to a controlled release from a working mine site (e.g. release of excess stored water) or uncontrolled release (e.g. erosion of material from a site). The radionuclides could concentrate during mining and mineral ore processing and incorporate in water bodies or traditional food stuffs, and thus contribute to the radiation dose received by the public. Eulerian approach to Partial Differential Equations (PDE) has been used to describe the relevant physical processes during radionuclide transport in the Taamang River. A computer programme has been written in MATLAB to implement the numerical solution of the PDE in order to estimate the activity concentration and annual committed effective dose to the public from natural radionuclides (NORM) in liquid effluent discharges from the gold processing plant at the Aboso goldmines in Damang, Tarkwa Ghana. The NORM elements of interest are 238U and 232Th decay chains. These radionuclides and some progenies such as 226Ra are long-lived. The key to understanding their distributions, therefore, is to understand the distribution of the source materials, and the physical and geochemical processes that lead to elevated concentrations of these radionuclides under specific conditions. The results obtained from the study revealed that the concentration of NORM in the Taamang River in Damang increases with time at the point of release and decreases due to its decaying character. For short-lived radionuclides, the concentration decreases rapidly as pollutants travel along the river corridor and approaches zero for both 224Ra and 210Po at 300 m from the discharged point. However, for long-lived radionuclides, the average activity concentrations were 0.06 Bq/L, 0.54 Bq/L and 0.78 Bq/L for 226Ra, 238U and 232Th respectively at 500 m from the discharged point where the water is used by the public. The corresponding average annual committed effective doses estimated were 0.01 μSv/y, 0.06 μSv/y, and 0.11 μSv/y for 226Ra, 238U and 232Th respectively. The results indicate an insignificant exposure of the public to Natural Occurring Radioactive Materials (NORM) from the activities of the Goldmine. The model designed will serve as an essential tool for use in the regulatory control of routine discharges of radionuclides into the environment and also in planning measures to be taken in the event of accidental releases from the mine.
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    Assessment Of The Level Of Environmental Pollution Due To Leachate Migration From The Closed Mallam SCC Waste Disposal Site, Accra - Ghana
    (University of Ghana, 2013-07) Odai, R.N.
    The closed Mallam State Construction Corporation (SCC) waste disposal site is one of the many unengineered and improperly decommissioned municipal solid waste (MSW) landfills in Accra, Ghana. The site served as a landfill site for the Accra Metropolitan Assembly (A.M.A) for 7 years and received variety of solid waste from the A.M.A and other neighbouring municipal assemblies. Leachate management plans were, however, not implemented. Untreated leachate from the waste disposal site flows through the human settlements around the waste disposal site and enter into nearby surface water (Bawere Stream). The site was closed in 2001 after several agitations from the people living around, coupled with the fact that it was full to its maximum. The waste disposal site was not properly decommissioned prior to its closure. As a result, untreated leachate from the site still flows through the human settlements and enter the Bawere Stream. The research was carried out to assess the level of contamination of surface water, soil and groundwater due to leachate migration from the closed waste disposal site with emphasis on major ions (Na+, K+, Ca2+, Mg2+, Cl-, HCO3- , SO42-, NO3-, and PO43- ) and trace elements (Fe, Pb, Cd, Cr, Mn, As, Zn, Hg, Cu and Co). Major ions were measured using conventional methods. Trace element concentrations were determined using Atomic Absorption Spectrometry. Stable isotopic composition (δ 18O and δ 2H) of the surface water, soil and groundwater were determined using the Liquid-Water Stable Isotope Analyzer (Off - Axis Integrated Cavity Output Spectroscopy via laser absorption). Results showed high level of contamination of the surface water. The mean concentrations of Na+, K+, Fe, Pb, Cd and Mn (388 mg/L, 53 mg/L, 0.046 mg/L, 0.229 mg/L and 0.234 mg/L respectively) in the surface water were above the maximum permissible limit of the WHO (1996) guideline for drinking water. The mean δ 18O and δ 2H values of the surface water were -1.59 o/oo vrs VSMOW and -10.79 o/oo vrs VSMOW respectively. Porosity of the soil in and around the closed waste disposal site decreased with depth while the volumetric water content increased with depth. Trace element contamination of the soil was low. However, elevated concentrations of most of the trace elements were observed near the ground surface between 0 and 60 cm depths of the profiles. The level of contamination of the groundwater was high. The mean concentrations of Na+, Fe, Cd and Mn (330 mg/L, 1.178 mg/L, 0.040 mg/L and 0.157 mg/L respectively) in the groundwater were above the maximum permissible limit of the WHO (1996) guideline for drinking water. It is recommended that the closed Mallam SCC waste disposal site should be properly decommissioned and future waste disposal sites in Ghana should be properly engineered to minimize surface water and groundwater contamination due to leachate migration.
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    A Comparative Study Of Radiofrequency Emissions From Roof Top Mobile Phone Base Station Antennas and Tower Mobile Phone Base Station Antennas Located at Some Selected Cell Sites in Accra, Ghana.
    (University Of Ghana, 2014-07) Atakpa, G.K
    RF radiation exposure from antennas mounted on rooftop mobile phone base stations have become a serious issue in recent years due to the rapidly developing technologies in wireless telecommunication. The heightening numbers of base station and their closeness to the general public has led to possible health concerns as a result of exposure to RF radiations. The primary objective of this study was to assess the level of RF radiation emitted from roof top mobile phone base station antennas and compare the measured results with the guidelines set by International Commission on Non-ionization Radiation. The maximum and minimum average power density measured from the rooftop sites inside buildings were 2.46x10-2 and 1.68x10-3 W/m2 respectively whereas that for outside buildings at the same rooftop site was also 7.44x10-5 and 3.35x10-3 W/m2 respectively. Public exposure quotient also ranged between 3.74x10-10 to 1.31x10-07 inside buildings whilst that for outside varied between 7.44x10-10 to 1.65x10-06. Occupational exposure quotient inside buildings varied between 1.66x10-11 to 2.11x10-09 whereas that for outside ranged from 3.31x10-09 to 3.30x10-07 all at the rooftop site. The results obtained for a typical tower base station also indicated that the maximum and minimum average power density was 4.57x10-1W/m2 and 7.13x10-3 W/m2 respectively. The public exposure quotient varied between 1.58x10-09 to 1.01x10-07 whilst that for occupational exposure quotient ranged between 3.17x10-10 to 2.03x10-08. The values of power densities levels inside buildings at rooftop sites are low compared to that of tower sites. This could be due to high attenuation caused by thick concrete walls and ceilings. The results obtained were found to be in compliance with ICNIRP and FCC guidance levels of 4.5 W/m2 and 6 W/m2 respectively.
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    Developing and Validating of Predictive Model for Radiofrequency Radiation Emission within the Vicinity of Fm Stations in Ghana
    (University of Ghana, 2016-07) Ahenkora-Duodu, K.
    The rapid growing number of FM stations with their corresponding antennas have led to an increase in the concern of the potential health risks that may arise as a result of exposure to RF radiations. The main objective of this research was to develop and validate a predictive model with real time measured data for FM antennas in Ghana. Theoretical and experimental assessment of radiofrequency emission due to FM antennas has been analysed. The maximum and minimum electric field spatial average recorded was 7.17E-01 ± 6.97E-01V/m at Kasapa FM and 6.39E-02 ± 5.39E-02V/m at Asempa FM respectively. At a transmission frequency range of 88 -108 MHz, the average power density of the real time measured data ranged between 3.92E-05W/m2 and 1.37E-03W/m2 whiles that of the FM model varied from 9.72E-03W/m2 to 5.35E-01W/m2 respectively. Results obtained showed a variation between measured power density levels and the FM model. The FM model overestimates the power density levels as compared to that of the measured data. The impact predictions were based on the maximum values estimated by the FM model, hence these results validates the credibility of the impact analysis for the FM stations. The general public exposure quotient ranged between 9.00E-03 and 2.68E-01 whilst that of the occupational exposure quotient varied from 9.72E-04 to 5.35E-02. The results obtained were found to be in compliance with the International Commission on Non-Ionizing Radiation Protection (ICNIRP) RF exposure limit.