Calculation of dose to soft tisse from implanted beta sources
Abstract
Treatment of Arterio-Venous Malformation (AVM) requires the occlusion of the unwanted arteries. Irradiation of a blood vessel wall with beta particles causes it to be permanently blocked by multiplication of the endothelial cells. For this purpose, spherical radioactive particles are injected into these arteries. This study deals with the development of BRAIN-DOSES, a computer code based on VARSKIN MOD2 and SADDE MOD2, which evaluates gamma and beta dose distributions for radioactive sources with five different geometries: point, line, shell cylinder, solid cylinder and solid sphere. Since the particles injected into the blood vessels can be modeled as a line of spheres, this work focuses on the development of a computational method for estimating the spatial distribution of absorbed dose around a line of spheres. BRAIN-DOSES uses integration of Berger point kernels over the source volume, employing the scaled point kernels tabulated by Berger in 1971. This method requires calculation of the beta particle path within the two media crossed, tissue and source material. Consequently, besides the computational approach, this study describes a detailed geometrical approach of the problem. Results obtained from calculations with BRAIN-DOSES have been used to evaluate the beta dose distribution in the capillary walls of the rete of pigs, a vascular system which may model an AVM. The source was a 418 CI line of spheres made of a mixture of 42.8% hydrated polyacrylonitrile (PAN), 49.8% powdered Pt-197 and 7.4% powdered Pr-142 (in weight percentage). The sphere diameters were from 150 to 350 gm.
Description
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Includes bibliographical references: p.48-49.
Issued also on microfiche from Lange Micrographics.
Includes bibliographical references: p.48-49.
Issued also on microfiche from Lange Micrographics.
Keywords
health physics., Major health physics.