African Journal of Medical Physics
African Journal of Medical Physics (AJMP) publishes novel and high-quality research papers and other material on all topics relating to medical physics, biomedical sciences, medical imaging and molecular imaging for diagnosis, therapy and disease management. The journal provides an effective way to publish original research articles, review articles, short communication, rapid communication, letter to the editor, case report etc. It strives with a passion to publish articles on diverse themes of theoretical, computational, experimental and related clinical research from across the globe on a sole platform where there will be a wide scope to share ideas Involved from latest on-going research. It is the goal of the journal to provide an international forum for education and training in medical physics, radiation oncology, radiation detection, radiation protection, radiation shielding, and radiation response, new technologies development and applications, diagnostic and radiotherapy physics and applications.
Volume 3 Number 1 (2020)
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Evaluation of IMRT and Double-Arc VMAT treatment plans in Head and Neck Cancer Cases: Our Experience at NSIA-LUTH Cancer Care
Akpochafor M. O., Adeneye S. O., Habeebu M. Y. M., Abe G. A., Lawal R., Sanya I. D., Abdallah E. Kotkat, Ibrahim EL Hamamsi, Mahmoud M. A., Durosinnmi-Etti F. A. and Aweda M. A.
The aim of this study was to evaluate and compare the treatment plans produced using Intensity modulated radiotherapy (IMRT) and double-arc volumetric modulated arc therapy (VMAT) techniques for head and neck cancer cases with respect to maximum dose (D98%); minimum dose (D2%); Conformity Index (CI); Homogeneity Index (HI); volume that received 95% of the prescribed dose (V95%) and dose received by organs at risk (OARs). For this study, fifteen (15) patients of head and neck cancer were randomly selected for analysis of dose distribution within targets. For all these patients, IMRT and double-arc VMAT plans were generated for each of them making a total of thirty (30) plans. Calculated doses to planning target volume (PTV) and OAR was compared. Five (5) or seven (7) beams were used for all IMRT plans while double arc were used in the VMAT plans. Dose volume histogram (DVH) was generated for each plan and analyzed for dose coverage to the targets V95% which is the volume that receives 95% of the prescribed dose. PTV coverage was nearly similar in both treatment techniques. The homogeneity index (HI) was higher for the double arc VMAT plans with a value of 0.08 ± 0.014 compared to 0.06 ± 0.020 for IMRT plans (p-value of 0.012). The double arc VMAT plans provided a better conformity with a conformity index CI95%= 0.981 ± 0.014 compared to CI95%= 0.978 ± 0.011 achieved with the IMRT plans (p-value of 0.533). The double arc VMAT plans achieved significant sparing of the organs at risk with a significant p-value of 0.011 and 0.035 to the spinal cord and left parotid glands respectively. Double arc VMAT plans provided better dose conformity and OAR sparing while more homogeneous target coverage was achieved with the IMRT plans.
Conformity and Homogeneity Indexes for Cancer of the Pelvic Region Treated with Three-Dimensional Conformal Radiation Therapy at the National Hospital, Abuja, Nigeria
Taofeeq A. Ige and Maruf Adewole
Anorectal, bladder, cervix and prostate cancers form 32.98% of cancer cases treated with three-dimensional conformal radiation therapy (3DCRT) at the National Hospital Abuja. Conformity Index (CI) and Homogeneity Index (HI) have been identified as efficient tools for performing independent evaluation of radiotherapy treatment plans. This study aims to verify the influence of location of Tumour site, Total volume of the Planned Target Volume (PTV) and Energy of photon beam on Conformity and Homogeneity Indexes. It also aims to establish CI and HI as veritable tools for plan evaluation in the Centre. Forty (40) patients managed with radiation therapy between May and December 2018, were selected for this study. The PTV was delineated based on the recommendations of ICRU 50 and 62. The HI was evaluated according to ICRU 83and CI was evaluated according to the recommendations of ICRU 62. All cases were radical cases and treated with four beams at different direction (box technique). All plans were performed, reviewed and approved on Monaco 5.11 treatment planning system. In all, the percentages of anorectal, bladder, cervix and prostate cases selected were 17.50%, 15.00%, 42.50% and 25.00% respectively. A retrospective analysis of the CI and HI was done using Microsoft Excel 2013.The ideal value of Homogeneity Index (HI) is 0 (zero) while that of Conformal Index (CI) is 1 (unity). The cases were grouped into 2, 4 and 4 for volume of PTV, Tumour site location and energy respectively. The mean CI is 0.95 ± 0.05 while the mean HI is 0.168 ± 0.164 for the total number of cases. Uterocervix has the best CI and HI of 0.9708 ± 0.0244. The difference between the CI and HI of PTV below 1000 cm3 and above 1000cm3 is 0.0125 and 0.0016 respectively. The combination of 6MV and 10MV for AP/PA and lateral fields shows the best CI and HI of 0.971 and 0.1046 respectively. However, when tested statistically using paired t-test and ANOVA, these means were found not to be statistically different (p > 0.05).The result from this study suggests that HI and CI are not influenced by the size of the PTV, Tumour site location or energy. Conformity and Homogeneity indexes were further confirmed to remain effective tools in the analysis of treatment plans.
Estimation of Mean Glandular Doses for Patients Undergoing Mammography Examination in Some Selected Centers in Lagos State, Nigeria
Joshua Josephine, Nzotta Chukwuemeka Christian, Joseph Dlama Zira, Abubakar Matthew Garba, Mohammed Sani Umar, Abdullahi Hassan Abdullahi, Bature Silas Shem
Mammography is the x-ray examination of breast tissues and it is useful in the early detection of breast diseases. The radiation dose absorbed during mammography is a risk factor since it can trigger carcinogenesis. Dose optimization in mammography is imperative due to the exposures of radiosensitive tissues. This study aimed to determine the mean glandular dose (MGD) in four selected medical radio-diagnostics Centers in Lagos State, Nigeria. The study was a prospective cross-sectional one carried out in four selected hospitals in Lagos State of Nigeria. Sixty-seven women consented for the study. The entrance surface doses were measured using pre-calibrated thermoluminescent dosimeter (TLD) chips. Patient information such as age, kVp, anode/filter combination, compressed breast thickness (CBT) were captured. The MGD was calculated using the ESD and the conversion factors published by Dance. The annealed TLD chips were placed at the upper inner quadrant of the breast before compression was applied. The CBT was then measured with a meter rule. About 10% of the TLD chips were used as control, the TLD chips were read with the TLD reader after exposure and the readings were multiplied with the conversion factors. This was done for both Cranio-caudal (CC) and mediolateral oblique (MLO) views of the breast and the MGD was computed. Analysis of variance was used to determine the relationship of MGD between the Centers studied. Statistical significance was set at P<0.05. The result showed an average mean glandular dose of 0.74mGy and the calculated mean glandular dose for CC and MLO views were 0.33-6.41mGy and 0.28-8.59mGy respectively. The Mean Glandular Dose value obtained in this study was lower than the reference value of the IAEA (3mGy). Moreover, the MGD also depends on other factors like breast glandularity, specific beam qualities which also contribute to dose optimization.
Scattered X-radiation Dose Rate from Body Regions during Diagnostic Examination in a Nigerian University Teaching Hospital
Martins G., Orosun M. M., Tchokossa P., Famurewa O. C., Aderibigbe A. S., Akinyose F. C. and Mark I. B.
The measurement and prediction of scattered radiation dose in diagnostic radiology is particularly important, owing to the increased use and complexity of X-radiation. It is known that patients treated with ionizing radiation carry a risk of developing cancer in their lifetime. This study measures the exposure rate of patients due to scattered X-rays at an angle of 90O, estimates the dose rate received due to scattered X-ray and aims to provide an understanding of the possibility of minimising the amount of scattered radiation in diagnostic examination at the Teaching Hospital Complex of Obafemi Awolowo University, Ile-Ife. The X-ray machine used was Varian Medical System Rad 12 X-ray tube with serial number 2226680. Gamma-Scout with serial number 038339 calibrated across a wide scale (0.01 up to 5,000 µSv/hr for easy reading of X-radiation) connected to computer system at a long distance (7 m) from X-ray source to display number of counts, pulse and dose rate in µSv/hr. The results revealed that scattered mean dose rate for skull is 5.93 µSv/hr, neck is 3.99 µSv/hr, chest is 10.42 µSv/hr, shoulder is 4.24 µSv/hr, forearm is 3.32 µSv/hr, wrist and hand is 2.06 µSv/hr, plain abdomen is 9.06 µSv/hr, lumbosacral is 8.67 µSv/hr, pelvis and thigh is 8.67µSv/hr, knee and leg is 2.26 µSv/hr, and the foot is 3.20 µSv/hr. The results of this study fall within the dose level limits recommended by the International Commissions on Radiological Protection (ICRP)on exposure dose which should not exceed <50 µSv annually or 100 µSv every 5 years. Radiation should be thoroughly blocked by the apron to protect the radiological technologist from radiation exposure. Finally, the exposure dose and working environment should be regularly assessed to help decrease the exposure dose of the radiologist in accordance with the ICRP recommendation.
Assessment of Dose to Patients Undergoing Computed Tomography Procedures at Selected Diagnostic Centers in Kano, Nigeria
Abdullahi A. Hassan, Umar Ibrahim, Taofeeq A. Ige, Joseph Dlama Zira, Bello A. Aisha and Rilwan Usman
Radiation dose levels for adult most common Computed Tomography (CT) examinations namely brain, chest and abdomen CT scans were studied. Radiation dose reports, scan parameters and demographic information were surveyed for a period of three – months. Ethical approvals were obtained from the research ethics committee of Ministry of Health and the studied centers. Data were randomly collected using a simple random technique from 131 adult patients with weights 70 ± 3kg. The General Electric 8 and 16-slice and 160-slice Toshiba CT scanners were used in the study. The data were analyzed using SPSS (version 20.0 Chicago) statistical software. The results indicated that the CTDIw and DLP values were (62.5 mGy and 2946mGy*cm), (9.9mGy and 663.3 mGy*cm) and (13.5 mGy and 1397 mGy*cm) for brain CT, chest CT and abdominal CT scans respectively. The study shows that the CTDIw values are relatively similar to those reported in established work by the European Commission. However, the DLP values are comparably higher than those of the European Commission. This revealed that there is need for robust and sustained optimization program so as to reduce patient doses without affecting diagnostic image quality.
Comparative Analysis of Treatment Plan Quality and Treatment Delivery Efficiency of Selected Brain Cancer Cases Using 6MV FFF and 6 MV FF Photon Beams
Abebe Tuguma Feye and Paola Chiovati
The goal of radiation treatment is to maximize the dose delivered to the lesion while minimizing the dose to neighboring tissues. In order to achieve this goal, one has to use appropriate treatment planning techniques and appropriate energies. The aim of this study is to compare treatment plan quality and treatment delivery efficiency for selected brain cancer cases using MV flattened and flattened filter free’photon beam. Fourteen patients with brain cancer were studied. Standard clinical constraints were provided by the physician for planning target volume (PTV) and OARs. All plans were optimized and calculated using AAA algorithm of Eclipse treatment planning system. All treatment parameters were set to be identical for flattened and the flattening filter free beam plans. The homogeneity index (HI), gradient index (GI), target coverage (TC) and conformity number (CN) extracted from Dose volume histogram were used to compare the plan quality. The monitor unit and beam on time were used to evaluate the delivery efficiency of treatment plans. From DVH analysis of organ at risk, FFF plans obtained better normal tissue sparing effect than FF plans in all techniques. In all techniques, FFF beams provide the same TC as the FF beams. However, the use of 6MV FFF beams offers a clear benefit in delivery time when compared to 6MV FF beams, especially for stereotactic radio surgery (SRS) treatment techniques. With regard to MU, no significance difference was observed for volumetric arc therapy(VMAT) and SRS techniques, but clear differences in MU were obtained in SRT and Intensity modulated radiotherapy(IMRT) techniques: 6MV FFF uses higher MU value than 6MV FF to achieve the same TC. The highest difference was obtained in IMRT in which 6MV FFF used MU that is 1.5 times those used by 6 MV FF. We concluded that 6MV FFF beams are a good choice especially for brain treatment with SRS techniques.
Validation of Machine Performance Check (MPC) Beam Output Change on Two TrueBeam Linac Systems
Kukiriza Grace, Valenti Marco and Parisotto Marco
Daily quality assurance (QA) is an essential requirement of modern radiotherapy. Validation of the performed QA tests is equally fundamental. Daily Machine Performance Check (MPC) tests were conducted on two newly acquired VARIAN linacs, TrueBeam STX (TB STX) and TrueBeam (TB) for the commissioned photon energies. This MPC data was compared with independent absolute dose measurements performed on the linacs. The aim of the study was to assess the beam output change on two TrueBeam linacs, and compare the outcomes against MPC integrated tool. A weekly percentage dose output variation was measured using a secondary dosimetric system (SS) consisting of RW3 solid water phantoms, farmer type ionization chamber and PTW’s Unidose electrometer over twelve (12) months for flattened photon energies on TB STX and six (6) months for flattening filter free (FFF) on TB STX, flattened and FFF photon energies on TB. The acquired MPC and SS data were compared using student’s t-test tool for paired samples with a significant threshold level α of 0.05. The mean difference and standard deviation of the beam output change measured with MPC and SS was computed, and graphs plotted. The observed average standard deviation between output variations measured with the SS and MPC tool were less than ±1% and the mean output change within ±2%. There was a good agreement between the output variation measured with the SS and MPC tool. The department decided to trust in the daily MPC tests supported by the weekly secondary dosimetric measurement system to assess linacs performance in comparison to MPC tool.
Evaluation of the Effect of Protracted Exposure of Rats to Mobile Phone Radiation
Olajide M. B., Faromika O. P. and Kade I. J.
This study is aimed at investigating the effect of radiation from mobile phone on body weight and haematological indices of male wistar albino rats. In this study, male wistar albino rats were continuously exposed to Radiofrequency electromagnetic radiation (RF-EMR) with frequency 900 MHz for 0, 4, 8 and 12 h per day for 30 days. The body weights of the animals were taken at 5-day interval. At the expiration of the experimental period, haematological parameters of the blood were evaluated. The results showed that repeated exposure to mobile phone radiation evoked a reduced body weight and decreased level in red blood cell, packed cell volume and haemoglobin in rats and this effect was markedly amplified with increased exposure duration to the RF-EMR. Intriguingly, there was a direct relationship between exposure duration and frequency to mobile phone radiation and the level of white blood cell counts. In conclusion, the present data provide a strong line of reason to suggest that increased exposure to mobile phone radiation may evoke anaemic condition and predispose frequent users of mobile phone calls to decreased immune system and opportunist infection.