Browsing by Author "Amuasi, J.H."
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Item Comparative Studies on Permanent Prostate Brachytherapy Pre-Plan and Real-Time Transrectal Ultrasound Guided Iodine-125 Seed Implants at Korle-Bu Teaching Hospital, Ghana(University of Ghana, 2013-06) Kalolo, T.L.; Kyere, A.W.K; Amuasi, J.H.; Tagoe, S.N.A.; University of Ghana, College of Basic and Applied Sciences, Department of Medical PhysicsThis research was carried out to investigate and compare the real-time and pre-plan implant at the Radiotherapy Department of the Korle-Bu Teaching Hospital, Ghana. Prowess Panther 4.5 treatment planning system and Variseed 7.2 software were used for pre-plan and real-time implant respectively. The study was conducted for eighty -three (83) patients treated for prostate cancer through real-time implant brachytherapy between September, 2008 to April, 2013. Thirty one patients (31) whose Ultrasound images were available were selected for the pre-plan study. The slices of ultrasound images were re-drawn on transparent A-4 sheets and later on scanned, contoured and registered in the treatment planning system (Prowess 4.5) .After planning, the volume to be implanted, total number of needles, seeds and the total activity of the source were displayed. Comparison was done with the pre-plan and real-time implant. In both cases the variation was below 5% as recommended in dosimetry. About 30-40% of the imported seeds were left un-used due to over-estimation of seeds ordered from the manufacturer (BARD Company-USA) .Hence this work (pre-plan) aims to solve this problem. The comparison for dosimetric parameters was assessed for prostate, urethra and rectum as (V95%, V100%,V150%, D90Gy, D90%) , (D90Gy, D90%, D30Gy , D30%) and ( V100% , D30Gy and D30%) respectively and the variation were within the limit of ± 5%. Comparison of dosimetric values for this work were done with other institutions, like Karolinska university hospital, Sweden, The institute of Curie / hospital Cochin Group Paris-France and European recommendations. The values reported at Korle-Bu teaching hospital (this work) were in good agreement with the international guidelines.Item Estimation of Contralateral Breast Dose for Tangential Breast Irradiation Using Gafchromic Film Ebt2(University of Ghana, 2016-07) Boamah, E.Y.; Amuasi, J.H.; Hasford, F.; Tagoe, S.; University of Ghana, College of Basic and Applied Sciences, Department of Medical PhysicsThe dose to the contralateral breast for tangential breast irradiation has been estimated using Gafchromic films EBT2. The data collected consisted of measurements taken with anthropomorphic female Rando phantom. The EBT2 films were scanned and read using ScanMaker 9800XL plus and ImageJ software. A calibration curve was constructed using fourth – order polynomial fit to the data and a calibration equation was obtained from the graph which was used to convert the grey values into doses. Comparison of dose to the contralateral breast using different wedge angles and different photon beam energies has been done. The mean dose to the contralateral breast recorded were 1.93 Gy and 3.14 Gy for 6 MV and 15 MV photon beams respectively. The results show that the mean dose to the contralateral breast for 6 MV using 60O motorised wedge produced higher surface dose to the contralateral breast than 30Oand 15O wedges respectively. Similarly the mean dose to the contralateral breast for 15 MV using 60O motorised wedge produced higher surface dose to the contralateral breast than 30O and 15O wedges respectively. Results from this study show that the dose to the contralateral breast increases with increasing wedge angle. Analysis of the results from the 6 MV and 15 MV shows that the 15MV photon beam produced a higher doses to the contralateral breast as compared with the 6 MV photon beam by 6.42%.Item Estimation of Contralateral Breast Dose for Tangential Breast Irradiation Using Gafchromic Film Ebt2(University of Ghana, 2016-07) Boamah, E.Y.; Amuasi, J.H.; Hasford, F.; Tagoe, S.; University of Ghana, College of Basic and Applied Sciences Department of Medical PhysicsThe dose to the contralateral breast for tangential breast irradiation has been estimated using Gafchromic films EBT2. The data collected consisted of measurements taken with anthropomorphic female Rando phantom. The EBT2 films were scanned and read using ScanMaker 9800XL plus and ImageJ software. A calibration curve was constructed using fourth – order polynomial fit to the data and a calibration equation was obtained from the graph which was used to convert the grey values into doses. Comparison of dose to the contralateral breast using different wedge angles and different photon beam energies has been done. The mean dose to the contralateral breast recorded were 1.93 Gy and 3.14 Gy for 6 MV and 15 MV photon beams respectively. The results show that the mean dose to the contralateral breast for 6 MV using 60O motorised wedge produced higher surface dose to the contralateral breast than 30Oand 15O wedges respectively. Similarly the mean dose to the contralateral breast for 15 MV using 60O motorised wedge produced higher surface dose to the contralateral breast than 30O and 15O wedges respectively. Results from this study show that the dose to the contralateral breast increases with increasing wedge angle. Analysis of the results from the 6 MV and 15 MV shows that the 15MV photon beam produced a higher doses to the contralateral breast as compared with the 6 MV photon beam by 6.42%.Item Intrinsic and tomographic evaluation of siemens e.cam® SPECT system at the Korle-Bu teaching hospital (Ghana)(Research Journal of Applied Sciences, Engineering and Technology, 2011-01) Sosu, E.K.; Hasford, F.; Nani, E.K.; Amuasi, J.H.; Otoo, F.Intrinsic and tomographic evaluation tests on the Siemens e.cam® Signature Series Single Photon Emission Computed Tomography (SPECT) system were conducted to ensure that it meets the specification required by the user and the capabilities claimed by the manufacturer after installation. The tests were performed according to National Electrical Manufacturers Association protocols and various measuring instrument and point sources containing 99 m-Tc were used. Intrinsic tests performed include intrinsic flood uniformity, intrinsic count rate performance in air and intrinsic energy resolution. Whole body scanning, SPECT resolution without scatter, SPECT resolution with inserts, SPECT uniformity and center of rotation were also evaluated. The intrinsic count rate performance measured was 300kcps as against manufactures' specification of 310 kcps, intrinsic energy resolution was 9.31% whiles manufacturers' specification was # 9.9% and center of rotation specification is that Max. X-Min. X< 1 pixel and RMS < 0.5 whiles values measured was 0.254 and 0.10 for LEAP and 0.092 and 0.083 for LEHR collimators. The evaluation confirm that the SPECT system met the requirements for clinical medical imagine and also the values obtained could be used as baseline data for future quality control. © Maxwell Scientific Organization, 2011.Item Planning Target Margin Calculations Based on the Evaluation of Electronic Portal Imaging During Prostate Cancer Radiotherapy(University of Ghana, 2016-07) Yaotse, K.M.; Amuasi, J.H.; Inkoom, S.; Tagoe, S.; University of Ghana, College of Basic and Applied Sciences Department of Medical PhysicsSet-up errors are the inherent features of the radiation treatment process. Coverage of target volume is a direct function of set-up margins, which should be optimized to prevent unintended irradiation of adjacent normal tissues. The aim of this study was to evaluate three dimensional set-up errors and propose optimum margins for target volume coverage in prostate cancer radiotherapy. 1620 Portal images were obtained for an average of 30 fractions per patient for 54 prostate cancer patients. Electronic Portal Image (EPI) displacements obtained with iViewGTTM imaging software along the three major axes (X, Y, Z) were analysed. Mean displacements, population systematic and random errors and Three-dimensional vectors of displacements were calculated using StatPlus 2009 Professional 5.8.0 and Microsoft Excel (2013). Planning target margins were calculated using three different published margin recipes; the International Commission on Radiation Units and measurements (ICRU) 62, Stroom and van Herk. The random errors (σ) along vertical, lateral and longitudinal were 3.19 mm, 4.13 mm and 3.83 mm respectively. Similarly, the systematic errors (Σ) were 1.81 mm, 2.83 mm and 2.51 mm along vertical, lateral and longitudinal axes respectively. The population mean (Mpop) displacement in vertical, lateral and longitudinal axes were -0.49 mm, 0.05 mm and -0.40 mm respectively and standard deviation in vertical, lateral and longitudinal axes were 3.75 mm, 5.20 mm and 4.76 mm respectively for the prostate cancer patients. Using ICRU report 62, the clinical target volume to planning target volume margins (CTV-PTV) were 3.67 mm, 5.00 mm and 4.58 mm along vertical, lateral and longitudinal axes respectively. The corresponding values were 5.85 mm, 8.54 mm and 7.69 mm with Stroom’s formula whiles 3.75 mm, 6.96 mm and 5.95 mm were with van Herk’s formula. The results suggest that there is a significant difference within the three major axes. Hence, the need for local departmental planning target margin protocol was recommended.Item A Study to Compare the Motorised Wedge Output Factor of an Elekta Synergy Linear Accelerator with Reference Data (TPS Data)(University of Ghana, 2016-07) Akosah, K.; Amuasi, J.H.; Inkoom, S.; Tagoe, S.N.A.; University of Ghana, College of Basic and Applied Sciences, Department of Medical PhysicsFor external beam radiotherapy treatments, high doses are delivered to the cancerous cell. Accuracy and precision of dose delivery are primary requirements for effective and efficient cancer treatment. The dose delivered to the patient might not be uniform and therefore need to be compensated for. In treatment these inhomogeneities are taken care of by using wedge filters and incorporating wedge factors in the Treatment Planning System. Computer controlled wedges were alternatives introduced by different manufacturers of which Motorized wedges (MW) is one of them. The MW was introduced by ELEKTA and this helps to overcome some of the shortcomings of physical wedges. The objectives of this study were to measure MW output factors for 6 MV and 15 MV photon energies for an ELEKTA Synergy. Secondly, to compare the results of MWOF obtained to that of the treatment planning system data. The Motorized Wedge Output Factors (MWOF) were measured for the ELEKTA Synergy for both 6 MV and 15 MV photon energies. With the help of PMMA solid water slabs phantom, the Elekta synergy, thermometer, barometer, PTW farmer type ionization chamber 30010 charges were collected at 100 cm source to surface distance for various square field sizes from 5x5 cm to 30x30 cm and depth of 1.5 cm and 2.5 cm for 6 MV and 15 MV photon energies. Comparing the results with the TPS data, an excellent agreement was found for 6 MV MWOF, with the percentage differences ranging from 0.03% to 1.50%, with a mean of 0.03%. The coefficient of variation of MWOF ranged from 0.023% to 1.07% and 0.001% to 12.89% for the two beams (6 MV and 15 MV) respectively. The relative differences between the calculated and the measured MWOFs increases with field size. In conclusion, there was general agreement between the calculated and measured MWOFs. The consistency of values provide further support that a standard dataset of photon and electron dosimetry could be established as a guide for future commissioning, beam modeling, and quality assurance purposes.