An analytical model of a kilovoltage beam phase space.
An analytical model of a kilovoltage beam phase space.
复制标题
千伏束相空间的分析模型。
DOI：
10.1118/1.598705
复制
发表时间：
1999
期刊：
影响因子：
3.8
通讯作者：
Beckham,W
中科院分区：
文献类型：
--
作者：
diSopra,FM;Keall,P;Beckham,W
我们在这个项目中的目标是量化千伏束相空间用于剂量计算。通过结合以下解析导出的X射线束产生特性来对相空间进行建模：由于足跟效应引起的强度变化、由于光子穿过的靶材料的不同量引起的能量变化以及有限的源尺寸。使用计算机程序生成所使用的初始能谱。采用蒙特卡罗代码来检查计算出的相空间的有效性。对于10×10和10个射野，使用模拟相空间计算的剂量分布与实验值的一致性分别在2%和4%以内，对于射野尺寸的中心80%。在视野内但在该范围外，观察到最大6%的差异（对于视野），然而，这些值处于锐梯度区域，因此几何偏移较小。曲线的“尾部”被低估了6%。由于实验（3%）和蒙特卡罗（1.5%）的不确定性，认为模型相空间可用于体模和场边界内的体内剂量测定计算。
Our aim in this project was to quantify a kilovoltage beam phase space for use in dose calculations. The phase space was modeled by incorporating the following analytically derived x‐ray beam production properties: the intensity variation due to the heel effect, the energy variation due to the differing amount of target material traversed by the photons, and the finite source size. The initial energy spectrum used was generated using a computer program. A Monte Carlo code was adapted in order to examine the validity of the calculated phase space. Dose distributions calculated using the modeled phase space for 10×10 and fields show agreement with experimental values to within 2% and 4%, respectively, for the central 80% of the field size. Within the field but outside this range a maximum of 6% difference (for the field) was observed, however, these values were in a region of sharp gradient and hence small geometric shift. The “tails” of the profiles were underpredicted by up to 6%. Due to uncertainties in experiment (3%) and Monte Carlo (1.5%), the modeled phase space is deemed acceptable for phantom andin‐vivodosimetric calculations within the field boundaries.