Radiological Physics and Advisory Division, Health, Safety and Environment Group, Bhabha Atomic Research Centre, Trombay, Mumbai, 400 085, India.
Homi Bhabha National Institute, Anushaktinagar, Mumbai, 400094, India.
Radiol Phys Technol. 2021 Sep;14(3):297-308. doi: 10.1007/s12194-021-00627-1. Epub 2021 Jul 2.
Based on FLUKA, the present study is aimed at calculating the microdosimetric distributions of electron beams (6, 12 and 18 MeV) for radiotherapy as a function of depth in water at a site-size of 1 μm using a tissue-equivalent proportional counter (TEPC). Using the calculated microdosimetric distributions, the depth-specific relative biological effectiveness (RBE) of electron beams used in radiotherapy is calculated based on the theory of dual radiation action (TDRA) and the microdosimetric kinetic model (MKM). The TDRA-based calculation shows the variation of RBE of an electron beam with the absorbed dose and depth in water. In this study, we compared the RBE values calculated based on the TDRA and MKM. The FLUKA-based microdosimetric distributions in water obtained using the pre-calculated electron fluence spectra resulted in an improvement in the computational efficiency by a factor of 110 when compared with a full simulation. Depending on the beam energy and depth of water, RBE was in the range 0.67-0.78. RBE at 10% survival of HSG tumor cells was 0.84, which was nearly independent of the depth and beam energy.
基于 FLUKA，本研究旨在计算水深处（1μm 位点大小）电子束（6、12 和 18 MeV）的微剂量分布，使用组织等效比例计数器（TEPC）作为功能。使用计算的微剂量分布，根据双辐射作用（TDRA）理论和微剂量动力学模型（MKM），计算放射治疗中使用的电子束的特定深度相对生物效应（RBE）。基于 TDRA 的计算显示了电子束的 RBE 随吸收剂量和水深处的变化。在这项研究中，我们比较了基于 TDRA 和 MKM 计算的 RBE 值。使用预先计算的电子通量谱在水中获得的基于 FLUKA 的微剂量分布，与完全模拟相比，计算效率提高了 110 倍。根据束能和水的深度，RBE 在 0.67-0.78 范围内。HSG 肿瘤细胞 10%存活时的 RBE 为 0.84，几乎与深度和束能无关。
