A finite-size pencil beam model for photon dose calculations in three dimensions.
A finite-size pencil beam model for photon dose calculations in three dimensions.
复制标题
用于三维光子剂量计算的有限尺寸笔形束模型。
DOI：
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发表时间：
1992
期刊：
影响因子：
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通讯作者：
E. Chaney
中科院分区：
文献类型：
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作者：
J. Bourland;E. Chaney
一个三维剂量计算模型，采用有限尺寸，发散，笔形束已经开发和证明钴-60伽马射线。通过将笔形射束光子注量与钴-60的蒙特卡罗点剂量核卷积，在半无限水体模中模拟方形横截面笔形射束。这种有限尺寸的笔形波束经过一次计算，成为一个新的数据库，利用它可以通过二维叠加建立更大的波束。铅笔束的注量分布，角度校正光束发散，迈尼奥德平方反比校正，径向和角采样率，误差传播，和计算时间进行了研究和报告。径向和角度采样率对精度有很大影响，其适当选择是重要的。通过有限尺寸笔形射束叠加计算的百分比深度剂量在通过全卷积计算的值的1%以内，并且与文献中的值的一致性在6%以内。后者的分歧被证明是由于一个低能量的光子组件，这是不建模在其他计算。计算时间测量表明笔形波束方法比全卷积和差分散射空气比（dSAR）方法的一种实现更快。
A three-dimensional dose computation model employing a finite-size, diverging, pencil beam has been developed and is demonstrated for Cobalt-60 gamma rays. The square cross-section pencil beam is simulated in a semi-infinite water phantom by convolving the pencil beam photon fluence with the Monte Carlo point dose kernel for Cobalt-60. This finite-size pencil beam is calculated one time and becomes a new data base with which to build larger beams by two-dimensional superposition. The pencil beam fluence profile, angle correction for beam divergence, the Mayneord inverse square correction, radial and angular sampling rates, error propagation, and computation time have been investigated and are reported. Radial and angular sampling rates have a great effect on accuracy and their appropriate selection is important. Percent depth doses calculated by finite-size pencil beam superposition are within 1% of values calculated by full convolution and the agreement with values from the literature is within 6%. The latter disagreement is shown to be due to a low-energy photon component which is not modeled in other calculations. Computation time measurements show the pencil beam method to be faster than full convolution and one implementation of the differential-scatter-air-ratio (dSAR) method.