Calculation of the Equivalent Dose of the First and the Most Important Secondary Particles in Brain Proton Therapy by Monte Carlo Simulation

Document Type : Original Paper


1 Department of Physics, Faculty of Physics, Isfahan University of Technology, Isfahan, Iran

2 Department of Biomedical Engineering, Faculty of Engineering, University of Isfahan, Isfahan, Iran


Introduction: Due to nuclear interactions between the tissues and high-energy protons, the particles, including neutrons, positrons, and photons arise during proton therapy. This study aimed at investigating the dose distribution of proton and secondary particles, such as positrons, neutrons, and photons using the Monte Carlo method.
Material and Methods: In this study, a beam of protons was utilized with the energies of 160 and 190 MeV, which are more popular for brain tumor treatment. This beam irradiated the brain phantom after passing through proton therapy nozzle components. This phantom has a tumor with a radius of 3 cm in its centre. The most important parts of the nozzle include magnetic wobbler, scatterer, ridge filter, and collimator.
Results: The results show that while using protons with the energy values of 190 and 160 MeV, the equivalent dose fractions in tumor, brain, skull, and skin to the total equivalent dose in the head are 61.8 (62.4%), 10.4(10.9%), 6.07(3.69%), and 21.7(23%), respectively, regarding the primary and secondary particles.
Conclusion: According to the obtained results, in spite of the fact that most of the equivalent dose was inside the tumor volume, the skin of head has received the noticeable dose during proton therapy of brain which needs more concern.


Main Subjects


    1. Tavakol M, Karimian A, Aldaavati M. Dose Assessment of Eye and Its Components in Proton Therapy by Monte Carlo Method. Iranian Journal of Medical Physics. 2014;11(1):205-14.
    2. Joshi B, Kushwaha M, Jain AK. On the discrepancy between proton and α-induced d-cluster knockout on 16O. Progress of Theoretical and Experimental Physics. 2016;2016 (12).
    3. Khan J, Kann BH, Pan W, Drachtman R, Roberts K, Parikh RR. Underutilization of proton therapy in the treatment of pediatric central nervous system tumors: an analysis of the National Cancer Database. Acta Oncologica. 2017;56(8):1122-5.
    4. Farah J, Sayah R, Martinetti F, Donadille L, Lacoste V, Herault J,et al. Secondary neutron doses in proton therapy treatments of ocular melanoma and craniopharyngioma. Radiation protection dosimetry. 2014;161(1-4):363-7.
    5. Zheng Y, Newhauser W, Fontenot J, Taddei P, Mohan R. Monte Carlo study of neutron dose equivalent during passive scattering proton therapy. Physics in medicine and biology. 2007; 52(15):4481-96.
    6. Zheng Y, Liu Y, Zeidan O, Schreuder AN, Keole S. Measurements of neutron dose equivalent for a proton therapy center using uniform scanning proton beams. Medical physics. 2012; 39(6):3484-92.
    7. Geng C, Moteabbed M, Seco J, Gao Y, Xu XG, Ramos-Méndez J, et al. Dose assessment for the fetus considering scattered and secondary radiation from photon and proton therapy when treating a brain tumor of the mother. Physics in medicine and biology. 2016; 61(2):683-95.
    8. Kettern K, Coenen H, QaimS. Quantification of radiation dose from short-lived positron emitters formed in human tissue under proton therapy conditions. Radiation Physics and Chemistry. 2009; 78(6):380-5.
    9. Seravalli E, Robert C, Bauer J, Stichelbaut4 F, Kurz C, Smeets J, et al. Monte Carlo calculations of positron emitter yields in proton radiotherapy. Physics in medicine and biology. 2012;57(6):1659-73.
    10. Reaction Rate. Available from:
    11. TENDL-2014 Nuclear data library. Available from:
    12. Akagi T, Higashi A, Tsugami H, Sakamoto H, Masuda Y, Hishikawa Y. Ridge filter design for proton therapy at Hyogo Ion Beam Medical Center. Physics in medicine and biology.2003; 48(22): 301-12.
    13. Riazi Z, Afarideh H, Sadighi-Bonabi R. Fast numerical method for calculating the 3D proton dose profile in a single-ring wobbling spreading system. Australasian Physical & Engineering Sciences in Medicine. 2011; 34(3): 317-25.
    14. Riazi Z, Afarideh H, Sadighi-Bonabi R. Influence of ridge filter material on the beam efficiency and secondary neutron production in a proton therapy system. Zeitschrift für Medizinische Physik . 2012; 22(3): 231-40.
    15. Eckerman K. Description of the Mathematical Phantoms. 2002: 1-48.
    16. ACE Libraries for Monte Carlo Transport Codes.
    17. ICRP, 2007. The 2007 Recommendations of the International Commission on Radiological Protection. ICRP Publication 103. Ann. ICRP 37 (2-4).