Thebaut J, Zavgorodni S
Department of Physics and Astronomy, University of Victoria, Victoria BC, Canada.
Phys Med Biol. 2006 Dec 7;51(23):N441-9. doi: 10.1088/0031-9155/51/23/N06. Epub 2006 Nov 15.
The Monte Carlo (MC) method provides the most accurate to-date dose calculations in heterogeneous media and complex geometries, and this spawns increasing interest in incorporating MC calculations in the treatment planning quality assurance process. This process involves MC dose calculations for the treatment plans produced clinically. Commonly used in radiotherapy, MC codes are BEAMnrc and DOSXYZnrc, which transport particles in a coordinate system (c.s.) that has been established historically and does not correspond to the c.s. of treatment planning systems (TPSs). Relative rotations of these c.s. are not straightforward, especially for non-coplanar treatments. Transformation equations are therefore required to re-calculate a treatment plan using BEAM/DOSXYZnrc codes. This paper presents such transformations for beam angles defined in a DICOM-compliant treatment planning coordinate system. Verification of the derived transformations with two three-field plans simulated on a phantom using TPS as well as MC codes has been performed demonstrating exact geometrical agreement of the MC treatment fields' placement.
蒙特卡罗（MC）方法能在非均匀介质和复杂几何结构中提供迄今为止最精确的剂量计算，这使得人们越来越有兴趣将MC计算纳入治疗计划质量保证过程。这个过程涉及对临床生成的治疗计划进行MC剂量计算。在放射治疗中常用的MC代码是BEAMnrc和DOSXYZnrc，它们在一个历史上建立的坐标系（c.s.）中传输粒子，该坐标系与治疗计划系统（TPSs）的坐标系不对应。这些坐标系的相对旋转并不简单，特别是对于非共面治疗。因此，需要变换方程来使用BEAM/DOSXYZnrc代码重新计算治疗计划。本文给出了在符合DICOM标准的治疗计划坐标系中定义的射束角度的此类变换。已经使用TPS以及MC代码对在体模上模拟的两个三野计划进行了推导变换的验证，证明了MC治疗野放置的精确几何一致性。
