Mary Bird Perkins Cancer Center, 4950 Essen Lane, Baton Rouge, LA 70809, USA.
J Appl Clin Med Phys. 2012 Mar 8;13(2):3606. doi: 10.1120/jacmp.v13i2.3606.
Volumetric-modulated arc therapy (VMAT) is an effective but complex technique for delivering radiation therapy. VMAT relies on precise combinations of dose rate, gantry speed, and multileaf collimator (MLC) shapes to deliver intensity-modulated patterns. Such complexity warrants the development of correspondingly robust performance verification systems. In this work, we report on a remote, automated software system for daily delivery verification of VMAT treatments. The performance verification software system consists of three main components: (1) a query module for retrieving daily MLC, gantry, and jaw positions reported by the linear accelerator control system to the record and verify system; (2) an analysis module which reads the daily delivery report generated from the database query module, compares the reported treatment positions against the planned positions, and compiles delivery position error reports; and (3) a graphical reporting module which displays reports initiated by a user anywhere within the institutional network or which can be configured to alert authorized users when predefined tolerance values are exceeded. The utility of the system was investigated through analysis of patient data collected at our clinic. Nearly 2500 VMAT fractions have been analyzed with the delivery verification system at our institution. The average percentage of reported MLC leaf positions within 3 mm, gantry positions within 2°, and jaw positions within 3 mm of their planned positions was 92.9% ± 5.5%, 95.9%± 2.9%, and 99.7% ± 0.6%, respectively. The level of agreement between planned and reported MLC positions decreased for treatment plans requiring larger MLC leaf movements between control points. Differences in the reported MLC position error between the delivery verification system and data extracted manually from the control system were noted; however, the differences are likely systematic and, therefore, may be characterized if appropriately accounted for. Further investigation is needed to confirm the utility and accuracy of the system.
容积旋转调强放疗（VMAT）是一种有效的但复杂的放疗技术。VMAT 依赖于剂量率、旋转架速度和多叶准直器（MLC）形状的精确组合来实现强度调制模式。这种复杂性需要开发相应的强大性能验证系统。在这项工作中，我们报告了一种用于日常 VMAT 治疗剂量验证的远程、自动化软件系统。性能验证软件系统由三个主要组件组成：（1）查询模块，用于从加速器控制系统检索到记录和验证系统的每日 MLC、旋转架和机架位置；（2）分析模块，读取从数据库查询模块生成的每日交付报告，将报告的治疗位置与计划位置进行比较，并编译交付位置错误报告；（3）图形报告模块，显示用户在机构网络内任何位置发起的报告，或者可以配置为在超出预定义容差值时提醒授权用户。该系统的实用性是通过我们诊所收集的患者数据进行分析来研究的。在我们的机构中，使用交付验证系统分析了近 2500 个 VMAT 分次。报告的 MLC 叶片位置在计划位置的 3mm 内、旋转架位置在 2°内和机架位置在 3mm 内的平均百分比分别为 92.9%±5.5%、95.9%±2.9%和 99.7%±0.6%。对于需要在控制点之间进行更大的 MLC 叶片运动的治疗计划，计划和报告的 MLC 位置之间的一致性水平降低。交付验证系统和从控制系统手动提取的数据之间报告的 MLC 位置误差存在差异；然而，这些差异可能是系统的，因此如果适当地考虑到，就可以进行特征描述。需要进一步的研究来确认系统的实用性和准确性。
