Slosarek Krzysztof, Rembielak Agata, Cramb Jim, Maciejewski Boguslaw
Treatment Planning Unit, Department of Radiotherapy, Center of Oncology-Maria Sklodowska-Curie Memorial Institute, Gliwice, Poland.
Med Dosim. 2004 Fall;29(3):179-83. doi: 10.1016/j.meddos.2004.04.005.
The CadPlan-Helios treatment planning system for intensity-modulated radiation therapy (IMRT) includes some physical parameters that are specified by the planner, and thus can be subjectively interpreted. The choice of the value of these parameters strongly depends on the practical experience of the planner. This paper presents some extremes of the optimization constraints, to illustrate some traps of IMRT planning. The examples used in this paper are not directly related to clinical situations and some problems were deliberately exaggerated. Treatment fields were defined as recommended by Memorial Sloan-Kettering Cancer Center procedures for prostate IMRT. Prostate plans were arranged using a 5-field technique and 20-MV photon beam. The target and critical structures were defined and contoured for CadPlan-Helios. All computer calculations were performed for the same field arrangement. The following optimization parameters and factors are presented and analyzed in examples to visualize the importance of each parameter: dose-volume constraints and priority factors, scatter distance, maximum number of iterations and termination tolerance. The presented analysis strongly suggests that all constraints and parameters should be recorded in individual planning charts because without their nominal values, any reanalysis or dose recalculation may be difficult.
用于调强放射治疗（IMRT）的CadPlan-Helios治疗计划系统包含一些由计划者指定的物理参数，因此可能会受到主观解读的影响。这些参数值的选择在很大程度上取决于计划者的实践经验。本文介绍了优化约束的一些极端情况，以说明IMRT计划中的一些陷阱。本文中使用的示例与临床情况没有直接关系，并且一些问题被故意夸大了。治疗野按照纪念斯隆凯特琳癌症中心前列腺IMRT的程序建议进行定义。前列腺计划采用五野技术和20兆伏光子束进行安排。为CadPlan-Helios定义并勾勒出靶区和关键结构。所有计算机计算均针对相同的野排列进行。在示例中呈现并分析以下优化参数和因素，以直观显示每个参数的重要性：剂量体积约束和优先级因素、散射距离、最大迭代次数和终止容差。所呈现的分析强烈表明，所有约束和参数都应记录在单独的计划图表中，因为如果没有它们的标称值，任何重新分析或剂量重新计算可能都很困难。
