Department of Medical Physics
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Item Assessing the impact of land use and land cover change on the Densu Delta wetland using Markov chain modeling and artificial neural networks(Environmental Challenges, 2024) Laar, C.; Annan, K.B.K; Abdul-Wahab, D.; et al.This study investigates the dynamics of land use and land cover (LULC) changes in the Densu Delta wetlands, a critical ecosystem in Ghana. Here, satellite images spanning from 1998 to 2023 were used to analyse the spatio temporal patterns of LULC changes and their implications for water bodies, wetlands, vegetations, bare lands and urban areas in the Densu Delta wetland. Employing advanced techniques such as Markov chain modelling and artificial neural networks (ANNs), the research assesses and predicts LULC alterations. Significantly, the largest loss of LULC is observed in the Densu Delta wetland, where wetlands transition to waterbody cover type (14.02 km2 ). Model validation for 2023 attests to the accuracy of the model, boasting a correctness percentage of 70% and a kappa value of 0.74. In-depth analyses explore regional variations in the Densu Delta wetlands, revealing distinct patterns in the rates of LULC change before and after 2013. Notably, urbanization emerges as a prom inent factor post-2013, with urban areas experiencing remarkable rates of change in the wetland. Transition matrices underscore the intricate interplay of different land cover classes over the years. Simulated LULC pre dictions for 2033 and 2043 highlight the urban land cover type as having the highest positive change, recording approximately 0.39% for the Densu Delta wetland. The wetland land cover in the Densu Delta wetland exhibit negative changes of about − 0.52%. The synthesis of LULC data enhances our understanding of the complex interactions shaping these critical ecosystems. This research offers valuable insights for sustainable environ mental conservation, emphasizing the pivotal role of informed urban planning policies. It also unveils potential challenges posed by climate change, advocating for a holistic approach to preserve these vital wetland ecosystems.Item A rare case of intusscusception in a 6-month-old baby(Radiology Case Reports 19, 2024) Fiagbedzi, E.; Arkorful, J.; Appiah, E.; et al.This case report discusses the clinical presentation, imaging findings, and successful management of a rare case of intussusception in a 6-month-old female infant referred to a regional hospital in Ghana. The patient presented with vomiting, lethargy, fever, and currant jelly stool. Differential diagnoses considered included Merkel diverticulum, volvulus, lymphadenopathy, and hypertrophic pyloric stenosis. Ultrasound imaging revealed a concentric lesion with characteristic signs of intussusception. Ileo-caeco coli intussusception was con firmed as the diagnosis. Surgical management was used for this patient. The postsurgery phase was without any complications. The patient recovered well and was discharged with a switch to oral medications. Infant intussusception is still a disease with a low morbidity rateItem Psychological contract breach and mental health: the role of equity sensitivity and self-control(Health and Technology, 2024) Wyk, B.V.; Hasford, F.; Nyakale, N.; Vangu, M.Background Computer software for absorbed dose quantification has been widely used in nuclear medicine. Different software tools have been written to improve dose assessment, especially in therapeutic nuclear medicine. Some software tools focusing on computational phantom models from the international commission of radiation protection and units (ICRP) while others on Monte Carlo-simulated models. While many studies have investigated therapeutic nuclear medicine dosimetry,. The authors have noticed that very few papers compare therapeutic software tools to each other; hence, a doctor of philosophy study was embarked on. The aim of our study was therefore to validate our in-house-developed software tool, Masterdose, using the commercial software, OLINDA/EXM 1.0, that was available in our department. Methods: Methodology was based on clinical patient data treated for neuroendocrine tumours with 177Lutetium (Lu)-DOTATATE at a South African hospital. All patients underwent the same SPECT acquisition protocol and were corrected for scatter. partial volume, collimator-detector response, gamma camera calibration, and attenuation. Correction factors were applied to images to convert counts to activity. The first cycle of peptide receptor radionuclide therapy (PRRT) for 11 single photon emission computed tomography (SPECT) patients were compared using the Masterdose and OLINDA/EXM 1.0 software tools at 1, 24, 72, and 168 h. Cumulated activity and the absorbed dose were compared for the two software tools. The absorbed dose difference was then compared using statistical Bland-Altman analysis. Results Masterdose and OLINDA/EXM 1.0 had different peptide receptor radionuclide therapy methodologies. This led to different results obtained for the software tools. The cumulative activities of Masterdose and DTK was 10.5% and 10.9% for the kidneys and tumors, respectively. On average, tumor-absorbed doses were nine times those of the kidneys. Bland–Altman analysis shows a non-systematic difference between the two software. Conclusion On average, the relative percentage difference between the cumulated activities and absorbed dose of the two software were 10.7%.Item Dosimetric evaluation of VMAT automated breast treatment plans: Towards the establishment of an institutional plan acceptability criteria(Polish Journal of Medical Physics and Engineering, 2023) Acquah, G.F.; Hasford, F.; Tagoe, S.N.A.; et al.Introduction: To evaluate the clinical suitability of the current facility-based treatment plan protocol in establishing acceptability criteria. Material and methods: Automated Volumetric Arc Therapy (VMAT) treatment plans were retrospectively evaluated for intact breast and chest-wall cancer patients from January 2021 to January 2023. Results: A total of 94 patients were planned and treated using automated contouring and VMAT planning technique. The number of patients planned and treated for intact breast and chest-wall were 41 (43.6%) and 53 (56.4%), respectively. The mean intact breast volumes for optimization (Brst_opt) receiving 95% and 105% of the prescribed doses were 92.80% ± 1.11 and 1.54% ± 1.02, respectively. Their corresponding mean chest-wall volumes for optimization (Chst_opt) were 90.65% ± 3.19 and 2.28% ± 2.99, respectively. For left-sided cases, the mean heart dose received was 4.61 Gy ± 1.76 and 5.18 Gy ± 1.55 for intact breast plans and that for chest-wall plans, respectively. The mean ipsilateral lung volume receiving 20 Gy of the prescribed dose was 12.22% ± 3.86 and 13.19% ± 3.74 for intact breast plans and chest-wall plans, respectively. For the Brst_opt and Chst_opt dose metrics were calculated; the mean homogeneity index (HI) was 0.14 ± 0.03 and 0.15 ± 0.04, mean uniformity index (UI) was 1.09 ± 0.03 and 1.11 ± 0.03, and mean conformity index (CI) were 0.92 ± 0.04 and 0.91 ± 0.04, respectively. Conclusions: The dosimetric evaluation shows a good dose distribution in the target volumes with minimal doses to the organs at risk (OAR). Assessment of the current data affirms the clinical usefulness of the facility-adopted protocol in achieving quality treatment plans for intact breast and chest-wall irradiations. The establishment of plan acceptability criteria will help achieve improved overall treatment outcomesItem Assessment of the Impact of Turbo Factor on Image Quality and Tissue Volumetrics in Brain Magnetic Resonance Imaging Using the Three-Dimensional T1-Weighted (3D T1W) Sequence(International Journal of Biomedical Imaging, 2023) Manson, E.N.; Inkoom, S.; Mumuni, A.N.; Shirazu, I.; Awua, A.K.Background. The 3D T1W turbo field echo sequence is a standard imaging method for acquiring high-contrast images of the brain. However, the contrast-to-noise ratio (CNR) can be affected by the turbo factor, which could affect the delineation and segmentation of various structures in the brain and may consequently lead to misdiagnosis. This study is aimed at evaluating the effect of the turbo factor on image quality and volumetric measurement reproducibility in brain magnetic resonance imaging (MRI). Methods. Brain images of five healthy volunteers with no history of neurological diseases were acquired on a 1.5 T MRI scanner with varying turbo factors of 50, 100, 150, 200, and 225. The images were processed and analyzed with FreeSurfer. The influence of the TFE factor on image quality and reproducibility of brain volume measurements was investigated. Image quality metrics assessed included the signal-to-noise ratio (SNR) of white matter (WM), CNR between gray matter/white matter (GM/WM) and gray matter/cerebrospinal fluid (GM/CSF), and Euler number (EN). Moreover, structural brain volume measurements of WM, GM, and CSF were conducted. Results. Turbo factor 200 produced the best SNR (median = 17 01) and GM/WM CNR (median = 2 29), but turbo factor 100 offered the most reproducible SNR (IQR = 2 72) and GM/WM CNR (IQR = 0 14). Turbo factor 50 had the worst and the least reproducible SNR, whereas turbo factor 225 had the worst and the least reproducible GM/WM CNR. Turbo factor 200 again had the best GM/CSF CNR but offered the least reproducible GM/CSF CNR. Turbo factor 225 had the best performance on EN (-21), while turbo factor 200 was next to the most reproducible turbo factor on EN (11). The results showed that turbo factor 200 had the least data acquisition time, in addition to superior performance on SNR, GM/WM CNR, GM/CSF CNR, and good reproducibility characteristics on EN. Both image quality metrics and volumetric measurements did not vary significantly (p > 0 05) with the range of turbo factors used in the study by one-way ANOVA analysis. Conclusion. Since no significant differences were observed in the performance of the turbo factors in terms of image quality and volume of brain structure, turbo factor 200 with a 74% acquisition time reduction was found to be optimal for brain MR imaging at 1.5 T.Item Patient skin dose measurement and risk of deterministic effect during fluoroscopy cardiac procedures(Oxford University Press, 2023) Inkoom, S.; Hasford, F.; et al.; Nana, R.N.This study aimed at assessing patient’s peak skin doses (PSD) during fluoroscopy cardiac procedures and proposed a look-up table to enhance the patient’s dose management. Perspex phantom and thermoluminescent dosemeters (TLD) were irradiated for different dose levels with X-ray equipment (Philips Azurion 7). It was found that PSD measures were higher than the kerma at the interventional reference point [K (IRP)] reported with factors 1.55, 1.75 and 2.88 for anterior posterior (AP0o), left anterior oblique (LAO45o) and right anterior oblique (RAO45o), respectively. The equations describing the correlation between the PSD measured Kerma area product and cumulative air kerma were found with R-square values of 0.98 and 0.99, respectively. The statistical analysis shows a strong linear correlation between PSD and K (IRP) (P-value = 0.05). It was also found that 27% of the patients population considered in this work received a skin dose higher than the threshold of deterministic effect of 2 Gy and a look-up table with the equation of fitness was proposed to be implemented in the facility for K (IRP) higher than 500 mGy.Item Evaluation of organ and effective doses using anthropomorphic phantom: A comparison between experimental measurement and a commercial dose calculator(Radiography, 2023) Akyea-Larbi, K.O.; Hasford, F.; Inkoom, S.; Tetteh, M.A.; Gyekye, P.K.Introduction: The aim of this study was to experimentally measure organ doses for computed tomog raphy (CT) procedures using thermoluminescence dosimeters (TLDs) on a RANDO anthropomorphic phantom and verify the measured doses using CT-Expo software. Methods: The phantom was irradiated using clinical CT scan protocols routinely used for specific pro cedures in the radiology department. Fifty TLD chips were used in this study. The scanning parameters (kVp, mA, s) used to scan the phantom were used as input parameters for CT-Expo dose estimations. Results: The TLD measured organ doses varied between 3.97 mGy for the esophagus and 56.22 mGy for the brain. High doses were recorded in the brain (37.80e56.22 mGy) and the eye lens (29.94 e36.16 mGy). Comparing the organ dose measurements between TLD and CT-Expo, the maximum organ dose difference was obtained for the eye lens. A comparison between the two methods for the other organs were all less than 32 %. The effective doses from the TLD measurements for the head, chest, and abdominopelvic CT examinations were 2.78, 6.67, and 17 mSv, respectively and CT-Expo were 2.20, 10.30, and 16.70 mSv, respectively. Conclusion: The experimental and computational results are comparable, and the reliability of the TLD measurements and CT-Expo dose calculator has been proven. Implications for study: A reason for the difference in dose measurements between the two methods has been attributed to the dissimilarity in the organ position in the Rando anthropomorphic phantom and the standard mathematical phantom used by CT-Expo. The experimental and computational results have been found to be comparable.Item Evaluation of the impact of magnetic feld homogeneity on image quality in magnetic resonance imaging: a baseline quantitative study at 1.5 T(Egyptian Journal of Radiology and Nuclear Medicine, 2023) Manson, E.N.; Mumuni, A.N.; Inkoom, S.; Shirazu, I.Background Magnetic resonance images can be afected in a number of ways by magnetic feld inhomogeneity. The study aimed to optimize the main magnetic feld homogeneity (MFH) by assessing how magnetic feld inho mogeneity afects the signal-to-noise ratio (SNR) and geometric distortion of images acquired along the diameter of a spherical volume phantom from the isocenter of the MRI scanner. Results The MFH ranged between 0.10 and 0.60 ppm. The best MFH and the maximum SNR were determined in the isocenter at 400 mm feld of view with the application of shim. However, for all the phantom positions, geomet rical distortion in images acquired at 200 mm feld of view was generally better and worse at 400 mm feld of view. MFH could be optimized to reduce geometrical distortion and increase SNR by increasing the receiver bandwidth and the number of excitations whiles complementing it with shimming during image acquisition. According to Chi square independent test, there were no signifcant diferences (p>0.05) in the MFH, SNR, and geometrical distortion values. Compared to fndings at higher feld strengths, it was observed that MRI systems of higher feld strengths (greater than 1.5 T) could ofer superior magnetic feld homogeneity and SNR without causing observable geometri cal distortion. Conclusions The optimal feld of view for the fast feld echo (FFE) sequence required to maximize MFH, SNR, and reduce distortion during image acquisition may vary across MRI systems of diferent feld strengths. To determine the appropriate feld of view, the method and results of this study could serve as a guide for medical physicists as part of their routine quality assurance test procedures.Item Africa’s readiness for artificial intelligence in clinical radiotherapy delivery: Medical physicists to lead the way(Physica Medica, 2023) Manson, E.N.; Hasford, F.; Sosu, E.K.; et al.Background: There have been several proposals by researchers for the introduction of Artificial Intelligence (AI) technology due to its promising role in radiotherapy practice. However, prior to the introduction of the tech nology, there are certain general recommendations that must be achieved. Also, the current challenges of AI must be addressed. In this review, we assess how Africa is prepared for the integration of AI technology into radio therapy service delivery. Methods: To assess the readiness of Africa for integration of AI in radiotherapy services delivery, a narrative review of the available literature from PubMed, Science Direct, Google Scholar, and Scopus was conducted in the English language using search terms such as Artificial Intelligence, Radiotherapy in Africa, Machine Learning, Deep Learning, and Quality Assurance. Results: We identified a number of issues that could limit the successful integration of AI technology into radiotherapy practice. The major issues include insufficient data for training and validation of AI models, lack of educational curriculum for AI radiotherapy-related courses, no/limited AI teaching professionals, funding, and lack of AI technology and resources. Solutions identified to facilitate smooth implementation of the technology into radiotherapy practices within the region include: creating an accessible national data bank, integrating AI radiotherapy training programs into Africa’s educational curriculum, investing in AI technology and resources such as electronic health records and cloud storage, and creation of legal laws and policies to support the use of the technology. These identified solutions need to be implemented on the background of creating awareness among health workers within the radiotherapy space. Conclusion: The challenges identified in this review are common among all the geographical regions in the Af rican continent. Therefore, all institutions offering radiotherapy education and training programs, management of the medical centers for radiotherapy and oncology, national and regional professional bodies for medical physics, ministries of health, governments, and relevant stakeholders must take keen interest and work together to achieve this goal.Item Preliminary Staff Dose Assessment for Common Fluoroscopy Guided Procedures at Korle-Bu Teaching Hospital, Accra, Ghana(Radiation Protection Dosimetry, 2019) Nana, R. N.; Boadu, M.; Moyo, M. N.; Gyekye, P. K.; Botwe, B. O.Preliminary studies on effective and eye lens doses of six Radiologists, four Cardiologists have been conducted for a period of 3 months. Electronic dosemeters positioned under and over lead apron of staff were used for the dosimetry. The estimated effective dose per month to Cardiologist and Radiologist were 0.01–0.07 mSv and 0.03–0.14 mSv, respectively. The estimated eye lens doses per month to Cardiologists and Radiologists were also 0.15–0.30 mSv and 0.53–3.39 mSv, respectively. The effective doses per month to staff were below the ICRP acceptable limit of 1.67 mSv/month but the upper limit of the range of estimated eye lens dose exceeded the ICRP acceptable limit by a factor of 2. Regular use of protective goggles and consistent eye lens dose monitoring is encouraged at the hospital for dose optimization.