The risk of radiation-induced second cancer and the late tissue loss due to Off-field doses in radiotherapy remain a serious concern. Monte Carlo (MC) simulation is currently one of the most accurate methods for calculating these doses. MC simulation model based on the Particle Simulation Tool (TOPAS) has been developed to simulate the off-field dose of an Elekta Synergy linear accelerator (Linac) emitting 6 MV photons. Measurements were taken in a water phantom using an ionization chamber to validate this model. The Percentage Depth Dose (PDD) at the depth of 0.0, 5.0, 10.0 and 15.0 cm from the beam axis for a 10 × 10 cm2 field size was measured and simulated. Off-field dose profiles at the depth of 1.5 (dmax), 5.0 and 10.0 cm for field sizes of 5 × 5, 10 × 10, 15 × 15, and 20 × 20 cm2 respectively were measured and simulated. Comparison of measured and simulated off-field dose values showed a good agreement. The average gamma passing rate of the PDDs and profiles curves for off-field doses were 87.5% and 98.11% respectively. The local dose difference based on the PDD curve between the measured and simulated was less than 6.0 % for all locations. For all field size considered in this study, the average difference between profile curves for off-field dose measured and simulated was 9.1%. PDDs and Profiles curves for off-field dose simulation uncertainties were less than 2.0% and 1.0% respectively. TOPAS-MC simulation model developed is a good representation of our 6 MV Linac Elekta Synergy for assessing off-field dose, which would be the primary cause of some secondary cancers.
References
[1]
Preston, D.L., Shimizu, Y., Pierce, D.A., Suyama, A. and Mabuchi, K. (2003) Studies of Mortality of Atomic Bomb Survivors. Report 13: Solid Cancer and Noncancer Disease Mortality: 1950-1997. Radiation Research, 160, 381-407. https://doi.org/10.1667/rr3049
[2]
Wilde, G. and Sjostrand, J. (1997) A Clinical Study of Radiation Cataract Formation in Adult Life Following Gamma Irradiation of the Lens in Early Childhood. British Journal of Ophthalmology, 81, 261-266. https://doi.org/10.1136/bjo.81.4.261
[3]
D’Agostino, E., Bogaerts, R., Defraene, G., de Freitas Nascimento, L., Van den Heuvel, F., Verellen, D., et al. (2013) Peripheral Doses in Radiotherapy: A Comparison between IMRT, VMAT and Tomotherapy. Radiation Measurements, 57, 62-67. https://doi.org/10.1016/j.radmeas.2013.04.016
[4]
Xu, X.G., Bednarz, B. and Paganetti, H. (2008) A Review of Dosimetry Studies on External-Beam Radiation Treatment with Respect to Second Cancer Induction. Physics in Medicine and Biology, 53, R193-R241. https://doi.org/10.1088/0031-9155/53/13/r01
[5]
Stovall, M., Blackwell, C.R., Cundiff, J., Novack, D.H., Palta, J.R., Wagner, L.K., et al. (1995) Fetal Dose from Radiotherapy with Photon Beams: Report of AAPM Radiation Therapy Committee Task Group No. 36. Medical Physics, 22, 63-82. https://doi.org/10.1118/1.597525
[6]
Chetty, I.J., Curran, B., Cygler, J.E., DeMarco, J.J., Ezzell, G., Faddegon, B.A., et al. (2007) Report of the AAPM Task Group No. 105: Issues Associated with Clinical Implementation of Monte Carlo-Based Photon and Electron External Beam Treatment Planning. Medical Physics, 34, 4818-4853. https://doi.org/10.1118/1.2795842
[7]
Low, D.A., Harms, W.B., Mutic, S. and Purdy, J.A. (1998) A Technique for the Quantitative Evaluation of Dose Distributions. Medical Physics, 25, 656-661. https://doi.org/10.1118/1.598248
[8]
Matsubara, H. (2023) Neutron Dose from a 6-MV X-Ray Beam in Radiotherapy. Radiological Physics and Technology, 16, 186-194. https://doi.org/10.1007/s12194-023-00705-6
[9]
Musolino, S.V. (2001) Absorbed Dose Determination in External Beam Radiotherapy: An International Code of Practice for Dosimetry Based on Standards of Absorbed Dose to Water; Technical Reports Series No. 398. Health Physics, 81, 592-593. https://doi.org/10.1097/00004032-200111000-00017
[10]
Perl, J., Shin, J., Schümann, J., Faddegon, B. and Paganetti, H. (2012) TOPAS: An Innovative Proton Monte Carlo Platform for Research and Clinical Applications. Medical Physics, 39, 6818-6837. https://doi.org/10.1118/1.4758060
[11]
Agostinelli, S., Allison, J., Amako, K., Apostolakis, J., Araujo, H., Arce, P., et al. (2003) GEANT4—A Simulation Toolkit. Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 506, 250-303. https://doi.org/10.1016/s0168-9002(03)01368-8
[12]
Faddegon, B., Ramos-Méndez, J., Schuemann, J., McNamara, A., Shin, J., Perl, J., et al. (2020) The TOPAS Tool for Particle Simulation, a Monte Carlo Simulation Tool for Physics, Biology and Clinical Research. PhysicaMedica, 72, 114-121. https://doi.org/10.1016/j.ejmp.2020.03.019
[13]
Shin, J., Perl, J., Schümann, J., Paganetti, H. and Faddegon, B.A. (2012) A Modular Method to Handle Multiple Time-Dependent Quantities in Monte Carlo Simulations. Physics in Medicine and Biology, 57, 3295-3308. https://doi.org/10.1088/0031-9155/57/11/3295
[14]
TOPAS Tool for Particle Simulation. https://www.topasmc.org/
[15]
Seco, J. and Verhaegen, F. (2013) Monte Carlo Techniques in Radiation Therapy. CRC Press.
[16]
Bednarz, B. and Xu, X.G. (2009) Monte Carlo Modeling of a 6 and 18 MV Varian Clinac Medical Accelerator for in-Field and Out-of-Field Dose Calculations: Development and Validation. Physics in Medicine and Biology, 54, N43-N57. https://doi.org/10.1088/0031-9155/54/4/n01
[17]
Brun, R. and Rademakers, F. (1997) ROOT—An Object Oriented Data Analysis Framework. Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 389, 81-86. https://doi.org/10.1016/s0168-9002(97)00048-x
[18]
Kry, S.F., Titt, U., Followill, D., Pönisch, F., Vassiliev, O.N., White, R.A., et al. (2007) A Monte Carlo Model for Out-of-Field Dose Calculation from High-Energy Photon Therapy. Medical Physics, 34, 3489-3499. https://doi.org/10.1118/1.2756940
[19]
Walters, B.R.B., Kawrakow, I. and Rogers, D.W.O. (2002) History by History Statistical Estimators in the Beam Code System. Medical Physics, 29, 2745-2752. https://doi.org/10.1118/1.1517611
[20]
Al-Saleh, W.M. and Hugtenburg, R.P. (2023) Monte Carlo Modelling of a 6 MV Elekta Linear Accelerator for in-Field and Out-of-Field Dosimetry. Radiation Physics and Chemistry, 203, Article 110584. https://doi.org/10.1016/j.radphyschem.2022.110584
[21]
Kry, S.F., Titt, U., Pönisch, F., Followill, D., Vassiliev, O.N., Allen White, R., et al. (2006) A Monte Carlo Model for Calculating Out-of-Field Dose from a Varian Beam. Medical Physics, 33, 4405-4413. https://doi.org/10.1118/1.2360013
[22]
Mohamed Sinousy, S.D., Marouf Attalla, A.E., Hassan Fathy, I., Fathi Ahmed, E.F. and Ahmed Farouk, E. (2020) Validation of Monte Carlo Model for Dose Evaluation Outside the Treatment Field for Siemens 6MV Beam. Iranian Journal of Medical Physics, 17, 410-420. https://doi.org/10.22038/IJMP.2019.42881.1646
[23]
Almberg, S.S., Frengen, J. and Lindmo, T. (2012) Monte Carlo Study of In-Field and Out-of-Field Dose Distributions from a Linear Accelerator Operating with and without a Flattening-Filter. Medical Physics, 39, 5194-5203. https://doi.org/10.1118/1.4738963
[24]
Joosten, A., Matzinger, O., Jeanneret-Sozzi, W., Bochud, F. and Moeckli, R. (2013) Evaluation of Organ-Specific Peripheral Doses after 2-Dimensional, 3-Dimensional and Hybrid Intensity Modulated Radiation Therapy for Breast Cancer Based on Monte Carlo and Convolution/Superposition Algorithms: Implications for Secondary Cancer Risk Assessment. Radiotherapy and Oncology, 106, 33-41. https://doi.org/10.1016/j.radonc.2012.11.012
[25]
Diallo, I., Haddy, N., Adjadj, E., Samand, A., Quiniou, E., Chavaudra, J., et al. (2009) Frequency Distribution of Second Solid Cancer Locations in Relation to the Irradiated Volume among 115 Patients Treated for Childhood Cancer. International Journal of Radiation OncologyBiologyPhysics, 74, 876-883. https://doi.org/10.1016/j.ijrobp.2009.01.040
