Toivola H
First Department of Obstetrics and Gynecology, Helsinki University Central Hospital, Finland.
Strahlenther Onkol. 1989 May;165(5):396-400.
Dose rate distribution of commercially available I-125 seeds is strongly anisotropic due to self absorption. Effects of this anisotropy to dose distribution of linear, planar and volume implants are studied. Results suggest that this anisotropy should be taken into account especially when one is considering dose distribution near the seeds. Angularly averaged distribution of single seed is found to cause serious deflections to isodoses of the implant in high dose region. To use true anisotropic dose rate distribution one must be able to evaluate angular orientation of seeds in the implant. A method is presented to compute this orientation also when seeds are poorly visible in radiographs.
由于自吸收，市售碘-125粒子的剂量率分布具有很强的各向异性。研究了这种各向异性对线性、平面和立体植入物剂量分布的影响。结果表明，尤其是在考虑粒子附近的剂量分布时，应考虑这种各向异性。发现单粒子的角度平均分布会在高剂量区域使植入物的等剂量线产生严重偏移。要使用真正的各向异性剂量率分布，必须能够评估植入物中粒子的角度取向。本文提出了一种即使在X线片上粒子显示不佳时也能计算这种取向的方法。
