容积调强弧形治疗在眼内癌治疗中的剂量学优势。
Dosimetric advantage of volumetric modulated arc therapy in the treatment of intraocular cancer.
作者信息
Deng Zhenxiang, Shen Lanxiao, Zheng Xiaomin, Zhou Yongqiang, Yi Jinling, Han Ce, Xie Congying, Jin Xiance
机构信息
Radiotherapy and Chemotherapy Department, the 1st Affiliated Hospital of Wenhzou Medical University, No.2 Fuxue Lane, Wenzhou, 325000, China.
出版信息
Radiat Oncol. 2017 May 10;12(1):83. doi: 10.1186/s13014-017-0819-7.
OBJECTIVE
The purpose of this study is to investigate the dosimetric advantages of volumetric modulated arc therapy (VMAT) in the treatment of intraocular cancer by comparing it directly with three-dimensional conformal radiotherapy (CRT) and intensity-modulated radiotherapy (IMRT).
METHODS
CRT plan, 7f-IMRT plan, and one-arc VMAT plan were generated for 14 intraocular cancer patients. Dosimetric and biological quality indices for target volume and organs at risks (OARs) were evaluated and compared.
RESULTS
The target coverage presented by V95 for CRT, IMRT and VMAT were 95.02% ± 0.67%, 95.51% ± 2.25%, and 95.92% ± 3.05%, respectively. The homogeneity index (HI) for CRT, IMRT and VMAT were 0.15 ± 0.05, 0.23 ± 0.05, and 0.23 ± 0.06, respectively. IMRT and VMAT greatly decreased the dose to ipsilateral lens compared with CRT with a D1 of 2972.66 ± 1407.12 cGy, 3317.82 ± 915.28 cGy and 4809.54 ± 524.60 cGy for IMRT, VMAT and CRT, respectively. Similar results were observed for ipsilateral eyeballs. IMRT and VMAT also spared better on brainstem, optical nerves and optical chiasm compared CRT. However, CRT achieved lower dose to the eyeballs compared with IMRT and VMAT. VMAT and IMRT showed mixed results on target coverage and OAR sparing. The average MUs and delivery time of IMRT and VMAT were 531.25 ± 81.21 vs. 400.99 ± 61.49 and 5.05 ± 0.53 vs.1.71 ± 0.69 min, respectively.
CONCLUSIONS
Although no clear distinction on PTV coverage among CRT, IMRT and VMAT plans was observed in the treatment of intraocular cancer, VMAT and IMRT achieved better homogeneity and conformity for target volume, and delivered fewer doses to ipsilateral lens and eyeballs compared with CRT. However, VMAT and IMRT increased the low dose volume to the contralateral OARs. Although VMAT and IMRT showed mixed results on target coverage and OAR sparing, VMAT decreased MU and delivery time significantly compared with IMRT. VMAT is a promising and feasible external beam radiotherapy technique in the treatment of intraocular cancer patients.
目的
本研究旨在通过将容积调强弧形放疗（VMAT）与三维适形放疗（CRT）和调强放疗（IMRT）直接比较，探讨其在眼内癌治疗中的剂量学优势。
方法
为14例眼内癌患者制定CRT计划、7野IMRT计划和单弧VMAT计划。评估并比较靶区和危及器官（OARs）的剂量学和生物学质量指标。
结果
CRT、IMRT和VMAT的V95所呈现的靶区覆盖率分别为95.02%±0.67%、95.51%±2.25%和95.92%±3.05%。CRT、IMRT和VMAT的均匀性指数（HI）分别为0.15±0.05、0.23±0.05和0.23±0.06。与CRT相比，IMRT和VMAT显著降低了同侧晶状体的剂量，IMRT、VMAT和CRT的D1分别为2972.66±1407.12 cGy、3317.82±915.28 cGy和4809.54±524.60 cGy。同侧眼球也观察到类似结果。与CRT相比，IMRT和VMAT对脑干、视神经和视交叉的保护也更好。然而，与IMRT和VMAT相比，CRT对眼球的剂量更低。VMAT和IMRT在靶区覆盖和OAR保护方面表现不一。IMRT和VMAT的平均机器跳数（MUs）和照射时间分别为531.25±81.21 vs. 400.99±61.49和5.05±0.53 vs. 1.71±0.69分钟。
结论
虽然在眼内癌治疗中，CRT、IMRT和VMAT计划在计划靶体积（PTV）覆盖方面没有明显差异，但与CRT相比，VMAT和IMRT在靶区体积上实现了更好的均匀性和适形性，并且向同侧晶状体和眼球输送的剂量更少。然而，VMAT和IMRT增加了对侧OARs的低剂量体积。虽然VMAT和IMRT在靶区覆盖和OAR保护方面表现不一，但与IMRT相比，VMAT显著降低了MUs和照射时间。VMAT是一种在眼内癌患者治疗中很有前景且可行的外照射放疗技术。
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