Kwok C S, Prestwich W V, Wilson B C
Med Phys. 1985 Jul-Aug;12(4):405-12. doi: 10.1118/1.595752.
In cancer radioimmunotherapy nonuniform distributions of radionuclides in geometrically irregular tumor volumes will be encountered. If the tumor is surrounded by a homogeneous layer of soft tissue, the radiation dose distribution in the tumor due to a beta-emitting nuclide can be calculated by convolution of the appropriate Loevinger's point source dose function, J, with the nuclide concentration distribution. Computer programs using fast Fourier transform techniques have been developed to evaluate the three-dimensional spatial convolution accurately and efficiently. Equivalent techniques have also been applied to gamma-emitting nuclides by replacing J in the convolution by the photon point isotropic specific absorbed fraction. Illustrative results are presented for the radiation dose distribution in a 1-ml target volume with activity distribution which is (i) uniform, (ii) limited by diffusion into the target volume, or (iii) limited by diffusion and shedding of radionuclide in the peripheral layers of the target volume. Calculations for the three cases are presented for 32P, 131I, and 15-, 30-, and 100-keV photon emitters.
在癌症放射免疫治疗中，会遇到放射性核素在几何形状不规则的肿瘤体积内分布不均匀的情况。如果肿瘤被一层均匀的软组织包围，那么由发射β射线的核素导致的肿瘤内辐射剂量分布可以通过将适当的勒温格点源剂量函数J与核素浓度分布进行卷积来计算。已经开发出使用快速傅里叶变换技术的计算机程序，以准确而高效地评估三维空间卷积。通过在卷积中用光子点各向同性比吸收分数代替J，等效技术也已应用于发射γ射线的核素。给出了在1毫升靶体积内具有以下活性分布的辐射剂量分布的说明性结果：（i）均匀分布；（ii）受扩散到靶体积内的限制；或（iii）受放射性核素在靶体积外周层的扩散和脱落的限制。针对32P、131I以及15keV、30keV和100keV光子发射体给出了这三种情况的计算结果。
