MIRD体模肺部γ内污染探测效率分布的蒙特卡罗模拟

Monte Carlo Simulation on Dectecion Efficiency Distributions of γ Internal Contamination in the MIRD Phantom Lungs

运用MCNP5程序,建立了基于MIRD数字体模的肺部γ内污染模型以及Na I(Tl)探测器模型,模拟计算了Na I(Tl)探测器对基于MIRD数字体模的肺部γ内污染的探测效率,获得了在多种空间位置上对沉积在肺部的9种能量γ射线的探测效率。模拟结果表明,在不同位置的探测效率并不完全符合人体肺部的解剖学结构,在右下肺位置可获得最高的探测效率,左下肺次之,左上肺最低。在探测器位置固定的情况下,探测效率随能量的增加,有先增高后降低的现象。

In order to obtain detection e?ciencies of nine kinds of gamma rays emitted by isotopes deposited in lungs at various measurement geometry, Monte Carlo N-Particle Transport Code 5 (MCNP5) has been employed to for calculation. The results show that the detection e?ciency in different locations of lung is not completely accord with human body’s anatomy structure. The e?ciency decreases gradually from lower-right lung, to lower-left lung, and then to upper-left lung. When the location of detector is fixed, with the increase of energy, the detection e?ciency rises up firstly and then falls down.