用蒙地卡羅法計算骨內貝他劑量

DETERMINATION OF DOSE IN BONE DUE TO BETA-RAYS BY MONTE CARLO METHOD

陳渙東(Huan Tong Chen) ； 葉偉文(Wei-Wen Yeh)

《中華放射線醫學雜誌》 5卷4期 (1980/12) Pp. 388-398

摘要

本文使用蒙地卡羅數學方法，以計算機程式計算貝他射線或康普吞電子在人骨中造成的劑量。這程式以貝他的射程公式爲主，計算射線穿過骨髓、骨膜或骨質時射線之部分能量沉積在各種介質中的情形。本文所考慮的骨結構不再是一種均質組織，而將骨髓、骨膜和骨質分別考慮。當射線穿過每個骨髓空穴時，其所行走的弦長，是根據弦長機率分布方程式作隨機選取。又本程式只討論射源及吸收能量的位置均在同一骨骼區域之內，且由於2百萬電子伏的電子在骨內射程很難超過1公分，在骨中取2公分爲邊長的立方體，足以顯示骨中能量分布的情形。

並列摘要

This work was developed for the determination of the β-ray or Compton electron energy distribution inside the human bone by Monte Carlo method. The calculation was based on the β range equation from which the energy deposited in the marrow cavities, trabecular or endosteal could be determined, when β-rays or Compton electrons passed through one of these structure regions. In this investigation, the model of bone is no longer a homogeneous region but was divided into three regions i.e., marrow cavities, trabecular and endosteal. The marrow cavity size was chosen randomly according to the marrow cavity size probability distribution function. The source and target organs were limited in the same specific region in bone. Since the range of the 2 MeV electrons is hardly over 1 cm, a 2 × 2 cm^2 rectangle is enough to describe the distribution of energy deposition.