Bachelor of Health Science (Medical Radiation) (HONS)
Master of Science (Medical Physics)
PhD (Oncology and Radiotherapy)
RESEARCH INTERESTS
Radiotherapy Dosimetry
Monte Carlo Simulation
Quality Assurance in VMAT, IMRT, SRS/SRT/ , SBRT
Hetergoneity effect in Radiotherapy Dosimetry
9
Scopus Publications
Scopus Publications
Evaluation of the volumetric modulated arc therapy (VMAT) as alternative to the intracavitary brachytherapy boost treatment in locally advanced cervical cancer: Retrospective study Hui Sin Tan, Reduan Abdullah, Nurul Nafisah Abdul Razak, Jayapramila Jayamani Journal of Radiotherapy in Practice, 2025 Purpose: Intracavitary brachytherapy (IBT) is the standard boost treatment for patients with locally advanced cervical cancer. Volumetric modulated arc therapy (VMAT) boost serves as an alternative to IBT boost, but it has inferior target tumour coverage and organ at risk (OAR) sparing. In this study, a pear-shaped dose distribution was generated in the applicator-guided (AG)-VMAT boost on the existing IBT boost patient by an intercomparison with the existing VMAT boost practice. Method: The treatment plan of eight patients treated with the VMAT boost and ten patients treated with the IBT boost was analysed. Then, the IBT boost CT images were exported from the OnCentra Brachytherapy treatment planning system (TPS) to Eclipse TPS to plan AG-VMAT boost to reproduce the pear-shaped dose distribution. Result: AG-VMAT boost successfully reproduced the pear-shaped outline using the 100% isodose line from the IBT boost. The IBT boost treatment planning had the best dosimetry coverage for tumours by D90 23·33 Gy and CI 1·00. The D2cc of the bladder, rectum and femoral heads in the VMAT boost were in significantly higher doses than IBT and AG-VMAT boosts (p ≤ 0·05). The cumulative EQD2 for the D90 in the IBT boost only fell within the tolerance limit. Meanwhile, the D2cc of all the OAR doses in these three techniques was within the dose constraint set by the American Brachytherapy Society (ABS). Conclusion: 24 Gy/3 fractions AG-VMAT boost successfully reproduced the pear-shaped dose distribution for D90 of the target, with D2cc of the OAR remaining within the ABS limit.
Diaphragm and lung dose in liver high-dose-rate interstitial brachytherapy: A dosimetry and toxicity report Keerthaanaa Yogabalan, Gokula Kumar Appalanaido, Ch’ng Ewe Seng, Jasmin Bin Jalil, Jayapramila Jayamani, Nor Hafizah Ishak, Nursyatina Abdul Raof, Reduan Bin Abdullah, Ahamed Badusha Mohamed Yoosuf, Muhamad Zabidi Ahmad, Bazli Md Yusoff, Mohd Zahri Abdul Aziz Journal of Contemporary Brachytherapy, 2025 Purpose:The aim of this study was to retrospectively analyze and report on dose-volume and clinical toxicity of liver high-dose-rate interstitial brachytherapy (HDR-IBT) used in diaphragm and lung tissue.Material and methods: Computed tomography (CT)-based liver HDR-IBT using Oncentra Brachy treatment planning system (TPS) plans of patients with malignant liver tumor (MLT) from September 2018 to June 2023 were reviewed to identify patients, whose diaphragm and lung tissue were within 100% prescription isodose.These organs at risk (OARs) were contoured in axial CT slices.Maximum point dose (D max ), dose to 0.2 cc, 0.5 cc, 1 cc (D 0.2cc , D 0.5cc , D 1cc ), and volume receiving 30 Gy and 50 Gy (V 30Gy and V 50Gy ) were analyzed.Toxicity data of these patients were retrieved from hospital electronic records.Results: The analysis included 27 patients with 43 and 36 MLTs, whose 100% prescription isodose of liver HDR-IBT plan was within diaphragm and lung tissue.Median prescription dose was 25 Gy (range, 15-25 Gy) in single-fraction.Median D max , D 0.2cc , D 0.5cc , and D 1cc of the diaphragm were 302 Gy (range, 54-396 Gy), 68 Gy (range, 38-234 Gy), 48 Gy (range, 32-128 Gy), and 35 Gy (range, 27-88 Gy), while for the lung, 90 Gy (range, 39-295 Gy), 55 Gy (range, 32-207 Gy), 44 Gy (range, 29-117 Gy), and 34 Gy (range, 25-79 Gy), respectively.Median V 30Gy and V 50Gy for the diaphragm were 1.1 cc (range, 0-5.8 cc) and 0.2 cc (range, 0-2.5 cc), while for the lung, 0.8 cc (range, 0-10.1 cc) and 0.1 cc (range, 0-2.3 cc), receptively.Two patients with repeated HDR-IBT sessions received cumulative D max diaphragm of 698 Gy and 792 Gy.At median follow-up of 23 months, no patient reported any suspicious symptom of radiation-induced diaphragm or lung injury.Conclusions: This is the first publication reporting diaphragm and lung tissue dose-volume and clinical toxicity in liver HDR-IBT.Small volume of diaphragm and lung tissue tolerated extreme high radiation doses [5 times of stereotactic body radiotherapy (SBRT) range in single fraction] without clinically significant toxicity.A standardized reporting for diaphragm and lung dose volume is needed for future liver HDR-IBT studies.The results of the current study can be employed in future for expanded indication of brachytherapy, such as CT-guided trans-thoracic lung brachytherapy.
Electronic Portal Imaging Device in Pre-Treatment Patient-Specific Quality Assurance of volumetric-modulated arc therapy delivery M. L. Lau, R. Abdullah, J. Jayamani Journal of Radiotherapy in Practice, 2023 Background: Radiotherapy treatment delivery is evaluated by a pre-treatment patient-specific quality assurance (PSQA) procedure to ensure the patient receives an accurate radiation dose. The current PSQA practice by using conventional phantoms requires more set-up time and cost of purchasing the tools. Therefore, this study aimed to investigate the efficiency of an electronic portal imaging device (EPID) of linear accelerator (LINAC) as a PSQA tool for volumetric-modulated arc therapy (VMAT) planning technique for nasopharyngeal carcinoma (NPC) treatment delivery. Methods: A NPC VMAT plan on a Rando phantom was performed by following the Radiation Therapy Oncology Group (RTOG) 0615 protocol. The gamma passing rate of the EPID and PSQA phantom (ArcCHECK) were compared among the gamma criteria of 3%/3 mm, 2%/2 mm and 1%/1 mm, respectively. Results: Both EPID and ArcCHECK phantom had distinguishable gamma passing rates in 3%/3 mm and 2%/2 mm with a difference of 0·87% and 0·30%, respectively. Meanwhile, the EPID system had a lower gamma passing rate than the ArcCHECK phantom in 1%/1 mm (21·23% difference). Furthermore, the sensitivity of the EPID system was evaluated and had the largest deviation in gamma passing rate from the reference position in gamma criteria of 2%/2 mm (41·14%) compared to the 3%/3 mm (25·45%) and 1%/1 mm (31·78%), discretely. The best fit line of the linear regression model for EPID was steeper than the ArcCHECK phantom in 3%/3 mm and 2%/2 mm, and vice versa in gamma criteria of 1%/1 mm. This indicates that the EPID had a higher sensitivity than the ArcCHECK phantom in 3%/3 mm and 2%/2 mm but less sensitivity in 1%/1 mm. Conclusions: The EPID system was efficient in performing the PSQA test of VMAT treatment in HUSM with the gamma criteria of 3%/3 mm and 2%/2 mm.
Dosimetric Analysis of Rhizophora‑based Phantom Material in Radiation Therapy Applications Using Monte Carlo GATE Simulation Siti Hajar Zuber, Muhammad Fahmi Rizal Abdul Hadi, Damilola Oluwafemi Samson, Jayapramila Jayamani, Nor Ain Rabaiee, Mohd Zahri Abdul Aziz, Nurul Ab. Aziz Hashikin, Chee Keat Ying, Mohd Fahmi Mohd Yusof, Rokiah Hashim Journal of Medical Physics, 2023 Purpose: This study aims to determine the percentage depth dose (PDD) of a phantom material made from soy-lignin bonded Rhizophora spp. particleboard coated with a gloss finish by using Monte Carlo Geant4 Application for Tomographic Emission (GATE) simulation. Materials and Methods: The particleboard was fabricated using a hot pressing technique at target density of 1.0 g·cm−3 and the elemental fraction was recorded for the simulation. The PDD was simulated in the GATE simulation using the linear accelerator Elekta Synergy model for the water phantom and Rhizophora phantom, and the results were compared with the experimental PDD performed by several studies. Beam flatness and beam symmetry were also measured in this study. Results: The simulated PDD for Rhizophora and water was in agreement with the experimental PDD of water with overall discrepancies of 0% to 8.7% at depth ranging from 1.0 to 15.0 cm. In the GATE simulation, all the points passed the clinical 3%/3 mm criterion in comparison with water, with the final percentage of 2.34% for Rhizophora phantom and 2.49% for the water phantom simulated in GATE. Both the symmetries are all within the range of an acceptable value of 2.0% according to the recommendation, with the beam symmetry of the water phantom and Rhizophora phantom at 0.58% and 0.28%, respectively. Conclusions: The findings of this study provide the necessary foundation to confidently use the phantom for radiotherapy purposes, especially in treatment planning.
Development and dosimetric evaluation of the IMRT prostate at outside-the-irradiated field in a heterogeneity male pelvis phantom J. Jayamani, N. D. Osman, A. A. Tajuddin, D. O. Samson, K. E. Kamaruddin, M. Z. Abdul Aziz Journal of Radiotherapy in Practice, 2023 Background: Intensity-modulated radiation therapy (IMRT) treatment delivery requires pre-treatment patient-specific quality assurance (QA) for the dosimetry verification due to its complex multileaf-collimator movement. The prostate target close position between the bladder and rectum requires a tight margin during planning, and mistreatment would have a huge impact on the patient. A commercially available QA tool consists of a homogeneous medium and does not represent an exact photon interaction on the tumour and also on the nearby healthy organ. Objective: A heterogeneous male pelvis phantom was developed and investigated the efficiency of the treatment planning system (TPS) calculation on the off-axis region. Methods: Polymethyl methacrylate was used for the phantom housing, and the material closed to the bladder, rectum and prostate density was chosen to construct the organ models. The phantom was scanned and validated by the computed tomography number and density. An IMRT treatment was planned in the Monaco TPS, and a thermoluminescent dosimeter (TLD-100) was used to validate the point dosimetry. In addition, an EGSnrc Monte Carlo simulation was carried out to validate the phantom dosimetry. Results & Discussion: The dose measurement between TLD-100, TPS, and EGSnrc was compared and validated in the pelvis phantom. In the prostate region, the dose difference was within ± 5%, and the maximum dose difference outside-the-irradiated field was up to 20·07 % and 47·31 % in TPS and TLD-100, respectively. Meanwhile, the measured dose was lower than the calculated dose, and it was apparent for the dose outside-the-irradiated field. Conclusion: The developed heterogeneity male pelvis phantom was validated and verified to be an important QA device for validating radiation dosimetry in the pelvis region. The dose outside-the-irradiated field was underestimated by both TPS and TLD, respectively.
Determination of the small-field output factor for 6 MV photon beam using EGSnrc Monte Carlo J Jayamani, KW Chuah, MZ Abdul Aziz Journal of Medical Physics, 2022 Accuracy of ionization chamber (IC) to measure the scatter output factor (Scp) of a linear accelerator (linac) is crucial, especially in small field (<4 cm × 4 cm). The common IC volume of 0.6 cc is not adequate for small-field measurement and not all radiotherapy centers can afford to purchase additional IC due to the additional cost. This study aimed to determine the efficiency of the EGSnrc Monte Carlo (MC) to calculate the Scp for various field sizes including small field in Elekta Synergy (Agility multileaf collimator) linac. The BEAMnrc and DOSXYZnrc user codes were used to simulate a 6 MV linac model for various field sizes and calculate the radiation dose output in water phantom. The modeled linac treatment head was validated by comparing the percentage depth dose (PDD), beam profile, and beam quality (Tissue Phantom Ratio (TPR)20,10) with the IC measurement. The validated linac model was simulated to calculate the Scp consisting of collimator scatter factor (Sc) and phantom scatter factor (Sp). The PDD and beam profile of the simulated field sizes were within a good agreement of ±2% compared with the measured data. The TPR20,10 value was 0.675 for field size 10 cm × 10 cm. The Scp, Sc, and Sp simulated values were close to the IC measurement within ±2% difference. The simulation for Sc and Sp in 3 cm × 3 cm field size was calculated to be 0.955 and 0.884, respectively. In conclusion, this study validated the efficiency of the MC simulation as a promising tool for the Scp calculation including small-field size for linac.
Variation of optimization techniques for high dose rate brachytherapy in cervical cancer treatment Ahmad Naqiuddin Azahari, Ahmad Tirmizi Ghani, Reduan Abdullah, Jayapramila Jayamani, Gokula Kumar Appalanaido, Jasmin Jalil, Mohd Zahri Abdul Aziz Nuclear Engineering and Technology, 2022 High dose rate (HDR) brachytherapy treatment planning usually involves optimization methods to deliver uniform dose to the target volume and minimize dose to the healthy tissues. Four optimizations were used to evaluate the high-risk clinical target volume (HRCTV) coverage and organ at risk (OAR). Dose-volume histogram (DVH) and dosimetric parameters were analyzed and evaluated. Better coverage was achieved with PGO (mean CI = 0.95), but there were no significant mean CI differences than GrO (p = 0.03322). Mean EQD2 doses to HRCTV (D90) were also superior for PGO with no significant mean EQD2 doses than GrO (p = 0.9410). The mean EQD2 doses to bladder, rectum, and sigmoid were significantly higher for NO plan than PO, GrO, and PGO. PO significantly reduced the mean EQD2 doses to bladder, rectum, and sigmoid but compromising the conformity index to HRCTV. PGO was superior in conformity index (CI) and mean EQD2 doses to HRCTV compared with the GrO plan but not statistically significant. The mean EQD2 doses to the rectum by PGO plan slightly exceeded the limit from ABS recommendation (mean EQD2 dose = 78.08 Gy EQD2). However, PGO can shorten the treatment planning process without compromising the CI and keeping the OARs dose below the tolerance limit.
Determination of computed tomography number of high-density materials in 12-bit, 12-bit extended and 16-bit depth for dosimetric calculation in treatment planning system Jayapramila Jayamani, Noor Diyana Osman, Abdul Aziz Tajuddin, Zaker Salehi, Mohd Hanafi Ali, Mohd Zahri Abdul Aziz Journal of Radiotherapy in Practice, 2019 AimThe main aim was to examine the effect of bit depth on computed tomography (CT) number for high-density materials. Analysis of the CT number for high-density materials using 16-bit scanners will extend the CT scale that currently exists for 12-bit scanners and thus will be beneficial for use in CT–electron density (ED) curve in radiotherapy treatment planning system (TPS). Implementation of this extended CT scale will compensate for tissue heterogeneity during CT–ED conversion in treatment planning.Materials and methodsAn in-house built phantom with 10 different metal samples was scanned using 80, 100 and 120 kVp in two different CT scanners. A region of interest was set at the centre of the material and the mean CT numbers together with data deviation were determined. Dosimetry calculation was performed by applying a direct anterior beam on 12-bit, 12-bit extended and 16-bit.ResultsHigh-density materials (&gt;4·34 g cm−3) in 16-bit depth provide disparities up to 44% compared to Siemens’ 12-bit extended. Influence of tube voltage showed a significant difference (p&lt;0·05) in both bit depth and CT number of the gold and amalgam saturated in 16-bit depth. A 120 kVp energy illustrated a low variation on CT number for different scanners, but dosimetry calculation showed significant disparities at the metal interface in 12-bit, 12-bit extended and 16-bit.FindingsHigh-density materials require 16-bit scanners to obtain CT number to be implemented in treatment planning in radiotherapy. This also suggests that proper tube voltage together with correct CT–ED resulted in accurate TPS algorithm calculation.
Optimisation of 12 MeV electron beam simulation using variance reduction technique J Jayamani, N A S Mohd Termizi, F N Mohd Kamarulzaman, M Z Abdul Aziz Journal of Physics Conference Series, 2017 Monte Carlo (MC) simulation for electron beam radiotherapy consumes a long computation time. An algorithm called variance reduction technique (VRT) in MC was implemented to speed up this duration. This work focused on optimisation of VRT parameter which refers to electron range rejection and particle history. EGSnrc MC source code was used to simulate (BEAMnrc code) and validate (DOSXYZnrc code) the Siemens Primus linear accelerator model with the non-VRT parameter. The validated MC model simulation was repeated by applying VRT parameter (electron range rejection) that controlled by global electron cut-off energy 1,2 and 5 MeV using 20 × 107 particle history. 5 MeV range rejection generated the fastest MC simulation with 50% reduction in computation time compared to non-VRT simulation. Thus, 5 MeV electron range rejection utilized in particle history analysis ranged from 7.5 × 107 to 20 × 107. In this study, 5 MeV electron cut-off with 10 × 107 particle history, the simulation was four times faster than non-VRT calculation with 1% deviation. Proper understanding and use of VRT can significantly reduce MC electron beam calculation duration at the same time preserving its accuracy.
