Weeks K J, Buchsbaum D J, Terry V H, Ten Haken R K
Department of Radiation Oncology, University of Michigan, Ann Arbor.
Radiother Oncol. 1991 Aug;21(4):269-72. doi: 10.1016/0167-8140(91)90052-i.
Relative to homogeneous scattering conditions in tissue-like materials, a large increase in dose for clinical electron beams can occur upstream from high atomic number heterogeneities due to backscattered electrons. The degree of this dose increase is uncertain due to the unknown energy distribution of the backscattered electron fluence. Cell survival after irradiation was studied for Chinese hamster cells at the depth of maximum dose in a clinical 6 MeV electron beam under normal scattering conditions and with the addition of a lead backscatter. No significant difference in cell survival was found between the two geometries when the dose increase due to the backscattered electron fluence was approximated by the product of the measured ionization and the normal scattering stopping power ratio.
与组织样材料中的均匀散射条件相比，由于反向散射电子的存在，临床电子束在高原子序数异质性上游可能会出现剂量大幅增加的情况。由于反向散射电子注量的能量分布未知，这种剂量增加的程度尚不确定。在临床6 MeV电子束的最大剂量深度处，研究了正常散射条件下以及添加铅反向散射体时中国仓鼠细胞受照射后的细胞存活情况。当用测量的电离值与正常散射阻止本领比的乘积来近似由于反向散射电子注量导致的剂量增加时，在两种几何条件下未发现细胞存活存在显著差异。
