Palta Jatinder R, Liu Chihray, Li Jonathan G
Department of Radiation Oncology, University of Florida, Gainesville, FL, USA.
Int J Radiat Oncol Biol Phys. 2008;71(1 Suppl):S108-12. doi: 10.1016/j.ijrobp.2007.05.092.
The current paradigm for the quality assurance (QA) program for intensity-modulated radiation therapy (IMRT) includes QA of the treatment planning system, QA of the delivery system, and patient-specific QA. Although the IMRT treatment planning and delivery system is the same as for conventional three-dimensional conformal radiation therapy, it has more parameters to coordinate and verify. Because of complex beam intensity modulation, each IMRT field often includes many small irregular off-axis fields, resulting in isodose distributions for each IMRT plan that are more conformal than those from conventional treatment plans. Therefore, these features impose a new and more stringent set of QA requirements for IMRT planning and delivery. The generic test procedures to validate dose calculation and delivery accuracy for both treatment planning and IMRT delivery have to be customized for each type of IMRT planning and delivery strategy. The rationale for such an approach is that the overall accuracy of IMRT delivery is incumbent on the piecewise uncertainties in both the planning and delivery processes. The end user must have well-defined evaluation criteria for each element of the planning and delivery process. Such information can potentially be used to determine a priori the accuracy of IMRT planning and delivery.
目前，调强放射治疗（IMRT）质量保证（QA）计划的模式包括治疗计划系统的QA、输送系统的QA以及针对患者的QA。尽管IMRT治疗计划和输送系统与传统三维适形放射治疗相同，但它有更多参数需要协调和验证。由于复杂的射束强度调制，每个IMRT射野通常包括许多小的不规则离轴射野，导致每个IMRT计划的等剂量分布比传统治疗计划的等剂量分布更适形。因此，这些特性对IMRT计划和输送提出了一套新的、更严格的QA要求。为验证治疗计划和IMRT输送的剂量计算及输送准确性而制定的通用测试程序，必须针对每种类型的IMRT计划和输送策略进行定制。采用这种方法的基本原理是，IMRT输送的总体准确性取决于计划和输送过程中的分段不确定性。最终用户必须对计划和输送过程的每个要素有明确的评估标准。此类信息有可能用于先验地确定IMRT计划和输送的准确性。
