基于快速旋转 O 型环 LINAC 双层堆叠多叶准直器和螺旋断层调强放疗技术治疗鼻咽癌的容积旋转调强计划的剂量学比较。
Dosimetric comparison between VMAT plans using the fast-rotating O-ring linac with dual-layer stacked MLC and helical tomotherapy for nasopharyngeal carcinoma.
机构信息
Department of Radiation Oncology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Irwon-Ro 81, Gangnam-Gu, Seoul, 06351, Republic of Korea.
出版信息
Radiat Oncol. 2022 Sep 12;17(1):155. doi: 10.1186/s13014-022-02124-0.
BACKGROUND
To compare the dosimetric profiles of volumetric modulated arc therapy (VMAT) plans using the fast-rotating O-ring linac (the Halcyon system) based on a dual-layer stacked multi-leaf collimator and helical tomotherapy (HT) for nasopharyngeal cancer (NPCa).
METHODS
For 30 NPCa patients, three sets of RT plans were generated, under the same policy of contouring and dose constraints: HT plan; Halcyon VMAT plan with two arcs (HL); and Halcyon VMAT plan with four arcs (HL), respectively. The intended dose schedule was to deliver 67.2 Gy to the planning gross target volume (P-GTV) and 56.0 Gy to the planning clinical target volume (P-CTV) in 28 fractions using the simultaneously integrated boost concept. Target volumes and organ at risks dose metrics were evaluated for all plans. Normal tissue complication probabilities (NTCP) for esophagus, parotid glands, spinal cord, and brain stem were compared.
RESULTS
The HT plan achieved the best dose homogeneity index for both P_GTV and P_CTV, followed by the HL and L plans. No significant difference in the dose conformity index (CI) for P_GTV was observed between the HT plan (0.80) and either the HL plan (0.79) or the HL plan (0.83). The HL plan showed the best CI for P_CTV (0.88), followed by the HL plan (0.83) and the HT plan (0.80). The HL plan (median, interquartile rage (Q1, Q3): 25.36 (22.22, 26.89) Gy) showed the lowest D in the parotid glands, followed by the HT (25.88 (23.87, 27.87) Gy) and HL plans (28.00 (23.24, 33.99) Gy). In the oral cavity (OC) dose comparison, the HT (22.03 (19.79, 24.85) Gy) plan showed the lowest D compared to the HL (23.96 (20.84, 28.02) Gy) and HL (24.14 (20.17, 27.53) Gy) plans. Intermediate and low dose regions (40-65% of the prescribed dose) were well fit to the target volume in HL, compared to the HT and HL plans. All plans met the dose constraints for the other OARs with sufficient dose margins. The between-group differences in the median NTCP values for the parotid glands and OC were < 3.47% and < 1.7% points, respectively.
CONCLUSIONS
The dosimetric profiles of Halcyon VMAT plans were comparable to that of HT, and HL showed better dosimetric profiles than HL for NPCa.
背景
为了比较基于双层堆叠多叶准直器的快速旋转 O 形环直线加速器（Halcyon 系统）的容积旋转调强弧形治疗（VMAT）计划和螺旋断层调强放疗（HT）在鼻咽癌（NPCa）中的剂量学特征。
方法
对 30 例 NPCa 患者，在相同的轮廓勾画和剂量限制条件下生成三组放疗计划：HT 计划；Halcyon VMAT 计划（两个弧，HL）；Halcyon VMAT 计划（四个弧，HL）。计划的目标剂量方案是在 28 个分次中，以同时整合的增量概念将 67.2 Gy 给予计划总靶区（P-GTV）和 56.0 Gy 给予计划临床靶区（P-CTV）。评估所有计划的靶区和危及器官剂量学指标。比较食管、腮腺、脊髓和脑干的正常组织并发症概率（NTCP）。
结果
HT 计划在 P_GTV 和 P_CTV 的剂量均匀性指数上均达到最佳，HL 计划和 L 计划次之。HT 计划（0.80）与 HL 计划（0.79）或 HL 计划（0.83）之间的 P_GTV 剂量适形指数（CI）无显著差异。HL 计划在 P_CTV 的 CI 上表现最好（0.88），HL 计划次之（0.83），HT 计划再次之（0.80）。HL 计划（中位数，四分位距（Q1，Q3）：25.36（22.22，26.89）Gy）显示腮腺的 D 值最低，其次是 HT（25.88（23.87，27.87）Gy）和 HL 计划（28.00（23.24，33.99）Gy）。在口腔（OC）剂量比较中，HT 计划（22.03（19.79，24.85）Gy）的 D 值最低，HL 计划（23.96（20.84，28.02）Gy）和 HL 计划（24.14（20.17，27.53）Gy）次之。与 HT 和 HL 计划相比，HL 计划中 OC 剂量（40-65%的处方剂量）更好地适形于目标体积。所有计划均满足其他危及器官的剂量约束，具有足够的剂量裕度。腮腺和 OC 的中位 NTCP 值的组间差异分别小于 3.47%和小于 1.7%。
结论
Halcyon VMAT 计划的剂量学特征与 HT 相当，HL 计划在 NPCa 中比 HL 计划具有更好的剂量学特征。
Zotero 插件