Departamento de Engenharia Nuclear (DEN/UFMG) & Programa de Pós-graduação em Ciências e Técnicas Nucleares (PCTN), Universidade Federal de Minas Gerais (UFMG), Av. Antônio Carlos, 6627, Pampulha, 31270-901 Belo Horizonte, MG, Brazil.
Centro de Desenvolvimento da Tecnologia Nuclear - CDTN/CNEN, Belo Horizonte, MG, Brasil.
Phys Med. 2020 Dec;80:363-372. doi: 10.1016/j.ejmp.2020.11.013. Epub 2020 Dec 4.
The effects of low energy electrons in biological tissues have proved to lead to severe damages at the cellular and sub-cellular level. It is due to an increase in the relative biological effectiveness (RBE) of these electrons with a decrease in their penetration range. That is, lower the range higher will be its RBE.Therefore, accurate determination of low energy electron range becomes a key issue for radiation dosimetry. This work reports on in-water electron tracks evaluated at low kinetic energy (1-50 keV) using isotropic mono-energetic point source approach suitably implemented by different general-purpose Monte Carlo codes. For this aim, simulations were performed using PENELOPE, EGSnrc, MCNP6, FLUKA and Geant4-DNA Monte Carlo codes to obtain the particle range, R,R,R. Finally, evaluation of dose point kernel (DPK), as used for internal dosimetry, was carried out as an application example. Scaled dose point kernels (sDPK) were estimated for a range of mono-energetic low energy electron sources. The non-negligible differences among the calculated sDPK using different codes were obtained for energy electrons up to 5 keV. It was also observed that differences of in-water range for low-energy electrons, due to the different general-purpose Monte Carlo codes, affected the DPKs used for dosimetry by convolution approach. Finally, the 3D dosimetry was found to be almost not affected at macroscopic clinical scale, whereas non-negligible differences appeared at the microscopic level. Hence, a thorough validation of the used sDPKs have to be performed before they could be used in applications to derive any conclusions.
低能电子在生物组织中的影响已被证明会导致细胞和亚细胞水平的严重损伤。这是由于这些电子的相对生物有效性 (RBE) 随着穿透范围的减小而增加。也就是说，穿透范围越低，其 RBE 就越高。因此，准确确定低能电子的射程成为辐射剂量学的关键问题。本工作报道了在低动能（1-50 keV）下使用各向同性单能点源方法在水中评估的电子轨迹，该方法由不同的通用蒙特卡罗代码适当地实现。为此，使用 PENELoPE、EGSnrc、MCNP6、FLUKA 和 Geant4-DNA 蒙特卡罗代码进行了模拟，以获得粒子射程 R、R 和 R。最后，作为应用示例，进行了剂量点核（DPK）的评估，该核用于内部剂量测定。估计了一系列单能低能电子源的缩放剂量点核（sDPK）。对于高达 5 keV 的能量电子，使用不同代码计算的 sDPK 之间存在不可忽略的差异。还观察到，由于不同的通用蒙特卡罗代码，低能电子在水中的射程差异会影响卷积方法用于剂量测定的 DPK。最后，在宏观临床尺度上，3D 剂量测定几乎不受影响，而在微观水平上则出现了不可忽略的差异。因此，在将使用的 sDPK 用于应用以得出任何结论之前，必须对其进行彻底验证。
