Evaluation of neutron spectra and dose equivalent from a Varian 2100C/D Medical Linear Accelerator: Monte Carlo simulation and a literature review

• Published in: Radioprotection 2021-04, Vol.56 (2), p.93-101
• Main Authors: Razghandi, S., Karimi-Shahri, K., Firoozabadi, M.M.
• Format: Article
• Language: English
• ISSN: 0033-8451; 1769-700X
• DOI: 10.1051/radiopro/2021002

In this study was carried out a review according to experimental and Monte Carlo studies in the literature on the neutron production from 18 MV, Varian 2100C/D linac. The effects of these neutrons were investigated on the total fluence, the energy spectra, and the dose equivalent. These factors were calculated as a function of depth and the radiation field size by simulation of linac head using of MCNPX2.6.0 code. The neutron strength was found equal to 1.23 × 10 12  nGy −1 .The results showed that with increasing the field size from 5 × 5 to 40 × 40 cm 2 , the neutron fluence and dose equivalent in the water phantom rose to the maximum value for 25 × 25 cm 2 field (3.05 × 10 7  ncm −2 Gy −1 and 3.14 mSvGy −1 respectively) and then decreased with increasing the field size. According to the results, the magnetite-steel, ordinary, and limonite-steel concrete walls significantly increased the neutron dose equivalent for about 27.4%, 17.2%, and 13.5%, respectively.