Kim Yongbok, Modrick Joseph M, Pennington Edward C, Kim Yusung
The University of Arizona, Tucson.
J Appl Clin Med Phys. 2016 Mar 8;17(2):405-426. doi: 10.1120/jacmp.v17i2.5818.
The objective of this work is to present commissioning procedures to clinically implement a three-dimensional (3D), image-based, treatment-planning system (TPS) for high-dose-rate (HDR) brachytherapy (BT) for gynecological (GYN) cancer. The physical dimensions of the GYN applicators and their values in the virtual applicator library were varied by 0.4 mm of their nominal values. Reconstruction uncertainties of the titanium tandem and ovoids (T&O) were less than 0.4 mm on CT phantom studies and on average between 0.8-1.0 mm on MRI when compared with X-rays. In-house software, HDRCalculator, was developed to check HDR plan parameters such as independently verifying active tandem or cylinder probe length and ovoid or cylinder size, source calibration and treatment date, and differences between average Point A dose and prescription dose. Dose-volume histograms were validated using another independent TPS. Comprehensive procedures to commission volume optimization algorithms and process in 3D image-based planning were presented. For the difference between line and volume optimizations, the average absolute differences as a percentage were 1.4% for total reference air KERMA (TRAK) and 1.1% for Point A dose. Volume optimization consistency tests between versions resulted in average absolute differences in 0.2% for TRAK and 0.9 s (0.2%) for total treatment time. The data revealed that the optimizer should run for at least 1 min in order to avoid more than 0.6% dwell time changes. For clinical GYN T&O cases, three different volume optimization techniques (graphical optimization, pure inverse planning, and hybrid inverse optimization) were investigated by comparing them against a conventional Point A technique. End-to-end testing was performed using a T&O phantom to ensure no errors or inconsistencies occurred from imaging through to planning and delivery. The proposed commissioning procedures provide a clinically safe implementation technique for 3D image-based TPS for HDR BT for GYN cancer.
本研究的目的是介绍用于临床实施基于三维（3D）图像的高剂量率（HDR）近距离放射治疗（BT）的妇科（GYN）癌症治疗计划系统（TPS）的调试程序。妇科施源器的物理尺寸及其在虚拟施源器库中的值在其标称值的基础上变化了0.4毫米。与X射线相比，钛制施源管和卵形体（T&O）在CT体模研究中的重建不确定性小于0.4毫米，在MRI上平均为0.8 - 1.0毫米。开发了内部软件HDRCalculator来检查HDR计划参数，如独立验证活性施源管或圆柱体探头长度以及卵形体或圆柱体尺寸、源校准和治疗日期，以及平均A点剂量与处方剂量之间的差异。剂量体积直方图使用另一个独立的TPS进行了验证。提出了用于调试体积优化算法和基于3D图像的规划过程的综合程序。对于线性优化和体积优化之间的差异，总参考空气比释动能（TRAK）的平均绝对差异百分比为1.4%，A点剂量为1.1%。不同版本之间的体积优化一致性测试结果显示，TRAK的平均绝对差异为0.2%，总治疗时间为0.9秒（0.2%）。数据表明，优化器应至少运行1分钟，以避免驻留时间变化超过0.6%。对于临床妇科T&O病例，通过将三种不同的体积优化技术（图形优化、纯逆向规划和混合逆向优化）与传统的A点技术进行比较来进行研究。使用T&O体模进行端到端测试，以确保从成像到规划和交付过程中不会出现错误或不一致情况。所提出的调试程序为基于3D图像的妇科癌症HDR BT的TPS提供了一种临床安全的实施技术。
