Department of Radiation Oncology, Tohoku University Graduate School of Medicine, Sendai, Japan.
Division of Radiation Oncology, Faculty of Medicine Ramathibodi Hospital, Mahidol University, Bangkok, Thailand.
J Appl Clin Med Phys. 2023 Apr;24(4):e13890. doi: 10.1002/acm2.13890. Epub 2023 Jan 7.
To study the dosimetry impact of deformable image registration (DIR) using radiophotoluminescent glass dosimeter (RPLD) and custom developed phantom with various inserts.
The phantom was developed to facilitate simultaneous evaluation of geometric and dosimetric accuracy of DIR. Four computed tomography (CT) images of the phantom were acquired with four different configurations. Four volumetric modulated arc therapy (VMAT) plans were computed for different phantom. Two different patterns were applied to combination of four phantom configurations. RPLD dose measurement was combined between corresponding two phantom configurations. DIR-based dose accumulation was calculated between corresponding two CT images with two commercial DIR software and various DIR parameter settings, and an open source software. Accumulated dose calculated using DIR was then compared with measured dose using RPLD.
The mean ± standard deviation (SD) of dose difference was 2.71 ± 0.23% (range, 2.22%-3.01%) for tumor-proxy and 3.74 ± 0.79% (range, 1.56%-4.83%) for rectum-proxy. The mean ± SD of target registration error (TRE) was 1.66 ± 1.36 mm (range, 0.03-4.43 mm) for tumor-proxy and 6.87 ± 5.49 mm (range, 0.54-17.47 mm) for rectum-proxy. These results suggested that DIR accuracy had wide range among DIR parameter setting.
The dose difference observed in our study was 3% for tumor-proxy and within 5% for rectum-proxy. The custom developed physical phantom with inserts showed potential for accurate evaluation of DIR-based dose accumulation. The prospect of simultaneous evaluation of geometric and dosimetric DIR accuracy in a single phantom may be useful for validation of DIR for clinical use.
研究使用放射性光致发光玻璃剂量计（RPLD）和定制的带有各种插件的体模进行变形图像配准（DIR）的剂量学影响。
该体模旨在方便同时评估 DIR 的几何和剂量准确性。使用四种不同的配置对体模的四个 CT 图像进行采集。为不同的体模计算了四个容积调强弧形治疗（VMAT）计划。将四种体模配置组合应用两种不同的模式。将相应的两个体模配置之间的 RPLD 剂量测量值进行组合。使用两种商业 DIR 软件和各种 DIR 参数设置以及一个开源软件，在相应的两个 CT 图像之间计算基于 DIR 的剂量累加。然后，将使用 DIR 计算得出的累积剂量与使用 RPLD 测量得到的剂量进行比较。
肿瘤替代物的剂量差值平均值为±0.23%（范围为 2.22%-3.01%），直肠替代物的剂量差值平均值为±0.79%（范围为 1.56%-4.83%）。肿瘤替代物的靶区注册误差（TRE）平均值为±1.36mm（范围为 0.03-4.43mm），直肠替代物的 TRE 平均值为±5.49mm（范围为 0.54-17.47mm）。这些结果表明，DIR 参数设置之间的 DIR 精度存在很大差异。
在我们的研究中，肿瘤替代物的剂量差值为 3%，直肠替代物的剂量差值在 5%以内。带有插件的定制物理体模具有准确评估基于 DIR 的剂量累加的潜力。在单个体模中同时评估几何和剂量 DIR 准确性的前景可能对 DIR 在临床应用中的验证有用。
