Lachaine Martin E, Gorman Jason C, Palisca Madeline G
Department of Radiation Oncology, The University of Arizona, Tucson, Arizona 85724, USA.
J Appl Clin Med Phys. 2003 Spring;4(2):149-55. doi: 10.1120/jacmp.v4i2.2530.
High dose rate (HDR) brachytherapy often involves optimization routines to calculate the dwell times and positions of a radioactive source along specified applicator paths. These routines optimize the dwells in such a way as to deliver the prescribed dose at one or more points while satisfying various constraints. The importance of independently verifying the doses calculated by the optimization software prior to treatment delivery has been recognized in various works, and is a requirement of various regulatory agencies. Most previous methods are specific to particular treatment configurations, or require a full replanning of the case. In this work we describe an in-house software which provides an independent verification of dose calculations in less than 3 min, which adds negligible additional waiting time for the patient, regardless of the number of applicators, paths of the applicators, or complexity of the dwell times and positions. In order to verify errors which may occur between the planning and delivery stages, the verification code directly uses the treatment file used to control the HDR afterloader to compute the dose. Since this file references the source positions in the frame of reference of the catheters, an algorithm is described to convert these positions to Cartesian coordinates. We validate the code for various arbitrary cases ranging from a single catheter to complex multicatheter plans, and show results for various clinical plans. The maximum discrepancy observed for these clinical plans is 2%.
高剂量率（HDR）近距离放射治疗通常涉及优化程序，以计算放射性源沿指定施源器路径的驻留时间和位置。这些程序以这样一种方式优化驻留，即在满足各种约束条件的同时，在一个或多个点处给予规定剂量。在各种研究中已经认识到在治疗实施前独立验证由优化软件计算的剂量的重要性，并且这是各种监管机构的要求。以前的大多数方法特定于特定的治疗配置，或者需要对病例进行全面重新规划。在这项工作中，我们描述了一种内部软件，它能在不到3分钟的时间内对剂量计算进行独立验证，无论施源器的数量、施源器的路径或驻留时间和位置的复杂性如何，这为患者增加的等待时间可忽略不计。为了验证在计划和实施阶段之间可能出现的误差，验证代码直接使用用于控制HDR后装治疗机的治疗文件来计算剂量。由于该文件在导管的参考系中引用源位置，因此描述了一种算法将这些位置转换为笛卡尔坐标。我们针对从单导管到复杂多导管计划的各种任意情况对代码进行了验证，并展示了各种临床计划的结果。这些临床计划中观察到的最大差异为2%。
