Medical Dosimetry Program, University of Wisconsin, La Crosse, WI 54601, USA.
Medical Dosimetry Program, University of Wisconsin, La Crosse, WI 54601, USA.
Med Dosim. 2022;47(3):252-257. doi: 10.1016/j.meddos.2022.04.002. Epub 2022 May 20.
Volumetric modulated arc therapy (VMAT) and 3D dynamic conformal arc therapy (DCAT) are 2 methods proven useful for the clinical implementation of stereotactic body radiation therapy (SBRT) for lung lesions however, similar comparisons of SBRT liver lesions are lacking. The purpose of this study was to determine if the conformity of dose, irradiated volume, and dose to organs at risk (OAR) are equivalent or improved with the use of DCAT as an alternative treatment method when compared to standard VMAT for SBRT delivery of palliative and early-stage liver lesions. Twenty patients with liver lesions sized 2.0 to 5.0 cm were selected for this study. Plans were created with both DCAT and VMAT techniques for each patient. Metrics evaluated included the mean heart, kidney, large bowel, small bowel, esophagus, and stomach doses, the lung volume receiving 20 Gy (V), the volume of the normal liver receiving 15 Gy (V), conformity index (CI), heterogeneity index (HI), and the irradiated volume or volume receiving 25 Gy (V). The p-values for the mean dose to kidneys, small bowel, esophagus, and the lung V were greater than 0.05, and no statistical difference could be determined between DCAT and VMAT. The p-values for the mean heart, large bowel, stomach, and liver V were less than 0.05, indicating statistical significance and superiority of VMAT for minimizing dose to these organs, especially V of the liver. The DCAT technique produced CI greater than 1.0 for all patients proving superior coverage, while standard VMAT produced significantly improved V with p-values less than 0.0001, and consequently higher HI.
容积旋转调强放疗（VMAT）和 3D 动态适形弧治疗（DCAT）是两种已被证明可用于临床立体定向体部放疗（SBRT）治疗肺部病变的方法，然而，对于 SBRT 治疗肝脏病变的方法，还缺乏类似的比较。本研究旨在确定与标准 VMAT 相比，使用 DCAT 作为替代治疗方法治疗姑息性和早期肝脏病变的 SBRT 时，在剂量、照射体积和危及器官（OAR）剂量方面的适形性是否等效或得到改善。本研究选择了 20 例肝脏病变大小为 2.0 至 5.0cm 的患者。为每位患者创建了 DCAT 和 VMAT 两种技术的计划。评估的指标包括平均心脏、肾脏、大肠、小肠、食管和胃剂量、接受 20Gy（V）的肺体积、接受 15Gy（V）的正常肝脏体积、适形指数（CI）、不均匀性指数（HI）以及照射体积或接受 25Gy（V）的体积。肾脏、小肠、食管和肺 V 的平均剂量的 p 值大于 0.05，无法确定 DCAT 和 VMAT 之间存在统计学差异。心脏、大肠、胃和肝脏 V 的平均剂量的 p 值小于 0.05，表明 VMAT 在尽量减少这些器官剂量方面具有统计学意义和优越性，特别是肝脏 V。所有患者的 DCAT 技术产生的 CI 均大于 1.0，证明覆盖范围更好，而标准 VMAT 则产生了显著改善的 V，p 值小于 0.0001，因此 HI 更高。
