Monte Carlo simulation of a 6 MV Varian Trilogy clinical linear accelerator using Geant4 for small-field dosimetry analysis
DOI:
https://doi.org/10.15392/2319-0612.2025.2958Palabras clave:
Monte Carlo simulation, Geant4, Varian Trilogy, small field dosi, gamma index, radiotherapyResumen
In recent decades, radiotherapy has advanced significantly due to the emergence of advanced clinical linear accelerators, enabling safer and faster treatments with reduced side effects. In this study, we present a Monte Carlo simulation of a 6 MV Varian Trilogy clinical linear accelerator using the Geant4 toolkit to analyze dosimetric parameters, with a focus on small photon fields. The simulation models phase-space files generated at key beam-modification stages. Validation was performed by comparing simulated depth dose curves (PDD) and dose profiles with experimental measurements for the 6 MV photon beam, employing the gamma index (3%/3 mm criteria) to quantify the degree of agreement in the PDDs. The results agreed within a 2% difference, with over 95% of points passing the gamma analysis for a 10 x 10 cm² field. The developed framework allows for the calculation of correction factors for small-field dosimetry, addressing challenges such as lateral electronic disequilibrium in high-energy 6 MV beams, and comparing them with established values in the literature. These capabilities are particularly important for measurements of small fields used in advanced radiotherapy techniques, including Stereotactic Radiosurgery (SRS) and Stereotactic Body Radiotherapy (SBRT), where high precision in dose deposition is essential. Overall, this work establishes a robust and flexible Geant4-based platform for simulating clinical linear accelerators, contributing to the development of more accurate dosimetric protocols for high-energy photon therapy in small fields. Preliminary observations suggest notable output factor discrepancies in small photon fields (<3x3 cm2), indicating the potential need for detector-specific correction factors. Ongoing analysis aims to confirm these trends.
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[1] CHETTY, I. J.; MARTEL, M. K.; JAFFRAY, D. A.; BENEDICT, S. H.; HAHN, S. M.; BERBECO, R.; DEYE, J.; JERAJ, R.; KAVANAGH, B.; KRISHNAN, S.; LEE, N.; LOW, D. A.; MANKOFF, D.; MARKS, L. B.; OLLENDORF, D.; PAGANETTI, H.; ROSS, B.; SIOCHI, R. A.; TIMMERMAN, R. D,; WONG, J. W. Technology for innovation in radiation oncology. International Journal of Radiation Oncology. Biology. Physics, v. 93, n. 3, p. 485-492, 2015. DOI: https://doi.org/10.1016/j.ijrobp.2015.07.007
[2] BAUMANN, M.; KRAUSE, M.; OVERGAARD, J.; DEBUS, J.; BENTZEN, S. M.; DAARTZ, J.; RICHTER, C.; ZIPS, D.; BORTFELD, T. Radiation oncology in the era of precision medicine. Nature Reviews Cancer, v. 16, n. 4, p. 234-249, 2016. DOI: https://doi.org/10.1038/nrc.2016.18
[3] KOKA, K.; VERMA, A.; DWARAKANATH, B. S.; PAPINENI, R. V. L. Technological advancements in external beam radiation therapy (EBRT): An indispensable tool for cancer treatment. Cancer Management and Research, v. 14, p. 1421-1429, 2022. DOI: https://doi.org/10.2147/CMAR.S351744
[4] WAHABI, J. M.; WONG, J. H. D.; MAHDIRAJI, G. A.; UNG, N. M. Feasibility of determining external beam radiotherapy dose using LuSy dosimeter. Journal of Applied Clinical Medical Physics, v. 25, n. 6, p. e14387, 2024. DOI: https://doi.org/10.1002/acm2.14387
[5] KINOSHITA, N.; SHIMIZU, M.; MOTEGI, K.; TSURUTA, Y.; TAKAKURA, T.; OGUCHI, H.; KUROKAWA, C. Quantification of uncertainties in reference and relative dose measurements, dose calculations, and patient setup in modern external beam radiotherapy. Radiological Physics and Technology, v. 18, n. 1, p. 58-77, 2024. DOI: https://doi.org/10.1007/s12194-024-00856-0
[6] DUAN, W.; WU, H.; ZHU, Y.; ZHAO, G.; ZHANG, C.; JIANG, J.; FAN, Z.; WANG, Z.; WANG, R. Dosimetric comparison of gamma knife and linear accelerator (VMAT and IMRT) plans of SBRT of Lung tumours. Scientific Reports, v. 14, n. 1, p. 22949, 2024. DOI: https://doi.org/10.1038/s41598-024-74397-2
[7] YANI, S. ; RHANI, M. F. ; SOH, R. C. X.; HARYANTO, F. ; ARIF, I. Monte Carlo simulation of varian clinac iX 10 MV photon beam for small field dosimetry. Internation Journal of Radiation Research, v. 15, n. 3, p. 275-282, 2017.
[8] BAGHERI, H.; SOLEIMANI, A.; GHAREHAGHAJI, N.; MESBAHI, A.; MANOUCHEHRI, F.; SHEKARCHI, B.; DORMANESH, B.; DADGAR, H. A. An overview on small-field dosimetry in photon beam radiotherapy: Developments and challenges. Journal Cancer Research and Therapeutics, v. 13, n. 2, p. 175-185, 2017. DOI: https://doi.org/10.4103/0973-1482.199444
[9] IAEA TRS report 483. Dosimetry of small static fields used in external beam radiotherapy. INTERNATIONAL ATOMIC ENERGY AGENCY, Vienna 2017.
[10] PALMANS, H.; ANDREO, P. HUQ, M. S.; SEUNTJENS, J.; CHRISTAKI, K. E.; MEGHZIFENE, A. Dosimetry of small static fields used in external photon beam radiotherapy: Summary of TRS-483, the IAEA-AAPM international Code of Practice for reference and relative dose determination. Medical Physics, v. 45, n. 11, p. e1123-e1145, 2018. DOI: https://doi.org/10.1002/mp.13208
[11] GHOLAMI, S. ; LONGO, F. ; NEDAIE, H. A. ; BERTI, A. ; MOUSAVI, M.; MEIGOONI, A. S. Application of Geant4 Monte Carlo simulation in dose calculations for small radiosurgical fields, Medical Dosimetry, v. 43, n. 3, p. 214-223, 2018. DOI: https://doi.org/10.1016/j.meddos.2017.08.007
[12] CHI, D. D.; TOAN, T. N.; HILL, R. A multi-detector comparison to determine convergence of measured relative output factors for small field dosimetry. Physical and Engineering Sciences in Medicine, v. 47, n. 1, p. 371-379, 2024. DOI: https://doi.org/10.1007/s13246-023-01351-3
[13] SPENKELINK, G. B.; HUIJSKENS, S. C.; ZINDLER, J. D.; DE GOEDE, M.; VAN DER STAR, W. J. VAN EGMOND, J.; PETOUKHOVA, A. L. Comparative assessment and QA measurement array validation of Monte Carlo and Collapsed Cone dose algorithms for small fields and clinical treatment plans. Journal of Applied Clinical Medical Physics, v. 25, n. 12, p. e14522, 2024. DOI: https://doi.org/10.1002/acm2.14522
[14] ANDREO, P. Monte Carlo simulations in radiotherapy dosimetry. Radiation Oncology, v. 13, n. 1, p. 121, 2018. DOI: https://doi.org/10.1186/s13014-018-1065-3
[15] OHIRA, S.; TAKEGAWA, H.; MIYAZAK, M.; KOIZUMI, M.; TESHIMA, T. Monte Carlo modeling of the Agility MLC for IMRT and VMAT calculations. In Vivo, v. 34, p. 2371-2380, 2020. DOI: https://doi.org/10.21873/invivo.12050
[16] ZHANG, F.; ZHOU, M.; LIU, J.; YUE, L.; DENG, L.; XU, Z; WANG, G. Benchmarking of electron beam parameters based on Monte Carlo linear accelerator simulation. Translational Cancer Research, Hong Kong, v. 9, n. 2, p. 577-584, 2020. DOI: https://doi.org/10.21037/tcr.2019.12.02
[17] RENIL MON, P. S.; MEENA-DEVI, V. N.; BHASI, S. Monte Carlo modelling and validation of the elekta synergy medical linear accelerator equipped with radiosurgical cones. Heliyon, v. 9, n. 4, p. e15328, 2023. DOI: https://doi.org/10.1016/j.heliyon.2023.e15328
[18] Varian Medical System. Available in: https://www.varian.com/en-au/products/radiotherapy/treatment-delivery/trilogy. Accessed in: November 5, 2024.
[19] Geant4 Collaboration. International Geant4 Collaboration. Available in: https://geant4.web.cern.ch/collaboration/. Accessed in: January 26, 2025.
[20] Book For Application Developers. Available in: https://geant4-userdoc.web.cern.ch/UsersGuides/ForApplicationDeveloper/html/index.html. Accessed in: Dezember 5, 2024.
[21] MyVarian. Available from: https://www.myvarian.com/. Accessed in: January 26, 2025.
[22] HEATH, E.; SEUNTJENS, J. Development and validation of a BEAMnrc component module for accurate Monte Carlo modelling of the Varian dynamic Millennium multileaf collimator. Physics in Medicine and Biology, v. 48, n. 24, p. 4045, 2003. DOI: https://doi.org/10.1088/0031-9155/48/24/004
[23] HOLANDA DE OLIVEIRA, A. C.; VIEIRA, J. W.; ZARZA MORENO, M.; ANDRADE LIMA, F. R. Experimental verification of a methodology for Monte Carlo modeling of multileaf collimators using the code Geant4. Brazilian Journal of Radiation Sciences, v. 6, n. 2, p. 1-14, 2018. DOI: https://doi.org/10.15392/bjrs.v6i2.324
[24] HOLANDA DE OLIVEIRA, A. C.; VIEIRA, J. W.; LIMA, F. R. A. Quimera: a simulation platform based on the code Geant4 for dose evaluation in radiotherapy. Brazilian Journal of Radiation Sciences, v. 6, n. 3, p. 1-18, 2018. DOI: https://doi.org/10.15392/bjrs.v6i3.816
[25] AAPM Report n. 72. Basic Applications of multileaf collimators. AMERICAN ASSOCIATION OF PHYSICISTS IN MEDICINE, Madison 2001.
[26] CORTÉS-GIRALDO, M. A.; QUESADA, J. M.; GALLARDO, M. I.; CAPOTE, R. An implementation to read and write IAEA phase-space files in GEANT4-based simulations. International Journal of Radiation Biology, v. 88, n. 1-2, p. 200-208, 2012. DOI: https://doi.org/10.3109/09553002.2011.627977
[27] LOW, D. A.; HARMS, W. B.; MUTIC, S.; PURDY, J. A. A technique for the quantitative evaluation of dose distributions. Medical Physics, v. 25, n. 5, p. 656-661, 1998. DOI: https://doi.org/10.1118/1.598248
[28] LOW, D. A.; DEMPSEY, J. F. Evaluation of the gamma dose distribution comparison method. Medical Physics, v. 30, n. 9, p. 2455-2464, 2003. DOI: https://doi.org/10.1118/1.1598711
[29] CHEN, M. ; LU, W. ; CHEN, Q. ; RUCHALA, K. ; OLIVEIRA, G. Efficient gamma index calculation using fast Euclidean distance transform. Physics in Medicine and Biology, v. 54, p. 2037-2047, 2009. DOI: https://doi.org/10.1088/0031-9155/54/7/012
[30] HENG LI, H.; DONG, L.; ZHANG, L.; YANG, J. N.; GILLIN, M. T.; ZHU, X. R. Toward a better understanding of the gamma index: Investigation of parameters with a surface-based distance method. Medical Physics, v. 18, n. 12, p. 6730-6741, 2011. DOI: https://doi.org/10.1118/1.3659707
[31] HUSSEIN, M.; CLARK, C. H.; NISBET, A. Challenges in calculation of the gamma index in radiotherapy - Towards good practice. Physica Medica, v. 36, p. 1-11, 2017. DOI: https://doi.org/10.1016/j.ejmp.2017.03.001
[32] DAS, S.; KHARADE, V.; PANDEY, V.; ANJU, K. V.; PASRICHA, R. K.; GUPTA, M. Gamma index analysis as a patient-specific quality assurance tool for high-precision radiotherapy: A clinical perspective of single institute experience, Cureus, v. 14, n. 10, p. e30885, 2022. DOI: https://doi.org/10.7759/cureus.30885
[33] TAI, D. T.; OMER, H.; QUOC, L. C.; HAI, N. X.; MINH, T. V.; SULIEMAN, A.; MATTAR, E.; TOUFIG, H.; TAMAM, N.; BRADLEY, D. A. An open-source software for calculating 1D gamma index in radiation therapy. Journal of King Saud University - Science, v. 35, n. 10, p. 102937, 2023. DOI: https://doi.org/10.1016/j.jksus.2023.102937
[34] ICRU report 24. Determination of absorbed dose in a patient irradiated by beams of X or gamma rays in radiotherapy. INTERNATIONAL COMMISSION ON RADIATION UNITS AND MEASUREMENTS, Bethesda 1976.
[35] MIFTEN, M.; OLCH, A.; MIHAILIDIS, D.; MORAN, J.; PAWLICKI, T.; MOLINEU, A.; LI, H.; WIJESOORIYA, K.; SHI, J.; XIA, P.; PAPANIKOLAOU, N; LOW, D. A. Tolerance limits and methodologies for IMRT measurement-based verification QA: Recommendations of AAPM Task Group No. 218. Medical Physics, v. 45, p. e53-e83, 2018. DOI: https://doi.org/10.1002/mp.12810
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Derechos de autor 2025 Andre Luiz de Carvalho Ribeiro, Alex Cristóvão Holanda de Oliveira, Leonardo Peres da Silva, Eduardo De Paiva
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