高エネルギー X 線 Narrow beam の物理特性

概要

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Recently, high-energy photon narrow beams, less than several cm in diameter, were going to use for the purpose of the stereotactic radiosurgery with a linear accelerator. In this paper, we analyzed the physical characteristics of high-energy X-ray narrow beams by means of a Monte Carlo simulation, and discussed their peculiar phenomena. When the beam size of high-energy X-ray became smaller, in addition to a decrement in the scattered doses, the decrease in the primary doses began from a certain beam size due to the failure of the electron equilibrium in the side direction. This caused sharp fall-off on the percentage depth doses, off-center ratios and output factors, with a shallowing the maximum dose depth. In dose calculations for high-energy X-ray narrow beams, it is necessary to estimate the primary doses, which take into account the electron transport.
社団法人日本放射線技術学会の論文
1992-07-01