Inhomogeneity effect in Varian Trilogy Clinac iX 10 MV photon beam using EGSnrc and Geant4 code system

6th Asian Physics Symposium

Yani, S.^1,2 ; Rhani, M.F.^3 ; Haryanto, F.^1 ; Arif, I.^1

Department of Physics, Faculty of Mathematics and Natural Sciences, Institut Teknologi Bandung, Jalan Ganesa 10, Bandung

40132, Indonesia^1

Akademi Kebidanan Pelita Ibu Kendari, Jalan Syech Yusuf 12, Kendari

90132, Indonesia^2

Department of Radiation Oncology, National University Cancer Institute Singapore, Singapore, Singapore^3

关键词: Absorbing medium;    Dose calculation;    Dose distributions;    Inhomogeneities;    Radiation dose distribution;    Radiation transport;    Spectrum distribution;    Water equivalent;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/739/1/012117/pdf
DOI  :  10.1088/1742-6596/739/1/012117

来源: IOP

【 摘 要 】

Treatment fields consist of tissue other than water equivalent tissue (soft tissue, bones, lungs, etc.). The inhomogeneity effect can be investigated by Monte Carlo (MC) simulation. MC simulation of the radiation transport in an absorbing medium is the most accurate method for dose calculation in radiotherapy. The aim of this work is to evaluate the effect of inhomogeneity phantom on dose calculations in photon beam radiotherapy obtained by different MC codes. MC code system EGSnrc and Geant4 was used in this study. Inhomogeneity phantom dimension is 39.5 × 30.5 × 30 cm3and made of 4 material slices (12.5 cm water, 10 cm aluminium, 5 cm lung and 12.5 cm water). Simulations were performed for field size 4 × 4 cm2at SSD 100 cm. The spectrum distribution Varian Trilogy Clinac iX 10 MV was used. Percent depth dose (PDD) and dose profile was investigated in this research. The effects of inhomogeneities on radiation dose distributions depend on the amount, density and atomic number of the inhomogeneity, as well as on the quality of the photon beam. Good agreement between dose distribution from EGSnrc and Geant4 code system in inhomogeneity phantom was observed, with dose differences around 5% and 7% for depth doses and dose profiles.