Assessment of the absorbed dose uncertainty of prostate due to tissue swelling and ‎radioactive sources displacement in brachytherapy using   Monte Carlo method

Aghaei, Z; Karimian, Alireza; Alamatsaz, M H

doi:10.47176/ijpr.20.4.41043

Assessment of the absorbed dose uncertainty of prostate due to tissue swelling and ‎radioactive sources displacement in brachytherapy using Monte Carlo method

Document Type : Original Article

Authors

Z Aghaei ¹

Alireza Karimian ²

M H Alamatsaz ¹

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

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

https://doi.org/10.47176/ijpr.20.4.41043

Abstract

Brachytherapy is a kind of cancer treatment in which radiation sources are implanted inside or close to the cancerous tissue. ‎The purpose of this research is to calculate the absorbed dose uncertainty of prostate tissue, due to its swelling, ‎displacement of the implanted seed sources and also, to address the effect of these factors simultaneously, in brachytherapy of prostate. ‎In this research, MCNPX2.6 code, the TG-43U1 protocol and ORNL body phantom were used to simulate the brachytherapy ‎of prostate using iodine-125 seed sources. In the first study, 84 sources of iodine with the shapes of seed and then points were ‎implanted inside the prostate with the volume of 38.01 cm³. The radiation absorbed dose was found to be 110.59 and ‎‎110.57 Gy, respectively. Considering the 50% prostate inflation after implantation, the radiation absorbed doses of prostate ‎showed a reduction of more than of 17%. In the second therapeutic plan, by using 76 seed sources of I-125, considering 12% ‎swelling of prostate and applying the displacement of seed sources in three directions: left–right (1.8mm), front-back (2.1mm) and top–‎down (3.4mm)), the radiation dose amount of the cancerous tissue was reduced about 21%. So, the results ‎of seed and point sources of brachytherapy were very close to each other. Therefore, in simulation studies, point sources can be used ‎instead of seed sources to reduce the computational complexity. Also, this research showed the effects of swelling and ‎displacement of brachytherapy sources on the amount of the absorbed dose of prostate and its treatment were‎ noteworthy.

Keywords

prostate cancer

brachytherapy

absorbed dose uncertainty

Monte Carlo method

https://www.who.int/health-topics/cancer#tab=tab_1,‎ Available on Date 2020, 25 March.‎

‏‏ S Bernard and S Vynckier, Physics in Medicine and Biology 50, 7 (2005) 1493.‎

‏‏ P Teles, S Barros, S Cardoso, A Facure, LAR Da Rosa, M. Santos, P Pereira Jr, P Vaz, and M Zankl, ‎Radiation protection dosimetry 165, 1-4 (2015) 482.‎

‏‏ H Westendorp, T Nuver, C Hoekstra, M Moerland, and A Minken, International Journal of Radiation ‎Oncology Biology Physics 96, 1 (2016) 197.‎

M Rivard, B Coursey, L DeWerd, W Hanson, M Saiful Huq, G Ibbott, M Mitch, R Nath, and J ‎williamson, Medical Physics 31, 3 (2004) 633.‎

‏ Y Yu, L Anderson, Z Li, D Mellenberg, R Nath, M C Schell, F Waterman, A Wu, and J Blasko, Medical ‎Physics 26, 10 (1999) 2054‎‏.‏

‏‏ M Rivard, Medical Physics 36, 2 (2009) 486.‎

‎‎ D R White, R V Griffith, I J Wilson, Journal of the International Commission on Radiation Units and ‎Measurements 24, 1 (1992) 122.‎

‎J Jarrett, "Experimental method development for direct dosimetry of permanent interstitial prostate ‎brachytherapy implants," Louisiana State University (2005).‎

10. ‎ F Waterman, N Yue, B Corn, and A Dicker, International Journal of Radiation Oncology Biology ‎Physics 41, 5 (1998) 1069.‎

11. ‎‎ B Taylor and C Kuyatt, US Department of Commerce, Technology Administration, National Institute ‎of Standards and Technology Gaithersburg (1994).‎

H Hedtjärn, G A Carlsson, and J F Williamson, Medical Physics 27, 5 (2000) 1076‎.