基于F-氟米索硝唑正电子发射断层扫描/计算机断层扫描引导的容积调强弧形放疗对鼻咽癌缺氧亚体积进行剂量递增的可行性研究。

F-Fluoromisonidazole positron emission tomography/CT-guided volumetric-modulated arc therapy-based dose escalation for hypoxic subvolume in nasopharyngeal carcinomas: A feasibility study.

作者信息

Qiu Jianjian, Lv Bo, Fu Meina, Wang Xianglian, Zheng Xiangpeng, Zhuo Weihai

机构信息

Institute of Radiation Medicine, Fudan University, Shanghai, China.

Department of Radiation Oncology, Fudan University Huadong Hospital, Shanghai, China.

出版信息

Head Neck. 2017 Dec;39(12):2519-2527. doi: 10.1002/hed.24925. Epub 2017 Sep 30.

DOI:10.1002/hed.24925

PMID:28963789

Abstract

BACKGROUND

The purpose of this study is to investigate the feasibility of a simultaneously integrated boost to the hypoxic subvolume of nasopharyngeal carcinomas (NCPs) under the guidance of F-fluoromisonidazole (FMISO) positron emission tomography (PET)/CT using volumetric-modulated arc therapy (VMAT) and intensity-modulated radiotherapy (IMRT) techniques.

METHODS

Eight patients with NPC were treated with simultaneous integrated boost-IMRT (treatment plan named IMRT70) with dose prescriptions of 70 Gy, 66 Gy, 60 Gy, and 54 Gy to the gross tumor volume (GTV), positive neck nodes, the planning target volume (PTV), and the clinically negative neck, respectively. Based on the same datasets, experimental plans with the same dose prescription plus a dose boost of 14 Gy (an escalation of 20% of the prescription dose) to the hypoxic volume target contoured on the pretreatment F-FMISO PET/CT imaging were generated using IMRT and VMAT techniques, respectively (represented by IMRT84 and VMAT84). Two or more arcs (approximately 2-2.5 arcs, totally rotating angle <1000 degrees) were used in VMAT plans and 9 equally separated fields in IMRT plans. Dosimetric parameters, total monitor units, and delivery time were calculated for comparative study of plan quality and delivery efficiency between IMRT84 and VMAT84.

RESULTS

In experimental plans, hypoxic target volumes successfully received the prescribed dose of 84 Gy in compliance with other dose constraints with either the IMRT technique or the VMAT technique. In terms of the target coverage, dose homogeneity, and organs at risk (OAR) sparing, there was no statistically significant difference between the actual treatment plan of IMRT70 and experimental plans. The total monitor unit of VMAT84 (525.7 ± 39.8) was significantly less than IMRT70 (1171.5 ± 167; P = .001) and IMRT84 (1388.3 ± 151.0; P = .001) per fraction, with 55.1% and 62.1% reduction. The average machine delivery time was 3.5 minutes for VMAT plans in comparison with approximately 8 minutes for IMRT plans, resulting in a reduction factor of 56.2%. For experimental plans, the 3D gamma index average was over 98.0% with no statistical significant difference when a 3%/3 mm gamma passing rate criteria was used.

CONCLUSION

With the guidance of F-FMISO PET/CT imaging, dose escalation to hypoxic zones within NPC could be achieved and delivered efficiently with the VMAT technique in comparison with the IMRT technique.

摘要

背景

本研究旨在探讨在¹⁸F-氟米索硝唑（FMISO）正电子发射断层扫描（PET）/CT引导下，使用容积调强弧形放疗（VMAT）和调强放疗（IMRT）技术对鼻咽癌（NPC）缺氧亚体积进行同步整合加量照射的可行性。

方法

8例NPC患者接受同步整合加量IMRT治疗（治疗计划命名为IMRT70），大体肿瘤体积（GTV）、阳性颈部淋巴结、计划靶体积（PTV）和临床阴性颈部的剂量处方分别为70 Gy、66 Gy、60 Gy和54 Gy。基于相同数据集，分别使用IMRT和VMAT技术生成实验计划，剂量处方相同，且对在治疗前¹⁸F-FMISO PET/CT影像上勾画的缺氧体积靶区给予14 Gy的剂量增量（处方剂量增加20%）（分别用IMRT84和VMAT84表示）。VMAT计划使用两条或更多弧形（约2 - 2.5条弧形，总旋转角度<1000度），IMRT计划使用9个等间隔野。计算剂量学参数、总监测单位和照射时间，以比较IMRT84和VMAT84之间的计划质量和照射效率。

结果

在实验计划中，无论使用IMRT技术还是VMAT技术，缺氧靶体积均成功接受了规定的84 Gy剂量，同时符合其他剂量限制。在靶区覆盖、剂量均匀性和危及器官（OAR）保护方面，IMRT70实际治疗计划与实验计划之间无统计学显著差异。VMAT84每分次的总监测单位（525.7 ± 39.8）明显少于IMRT70（1171.5 ± 167；P = .001）和IMRT84（1388.3 ± 151.0；P = .001），分别减少了55.1%和62.1%。VMAT计划的平均机器照射时间为3.5分钟，而IMRT计划约为8分钟，减少系数为56.2%。对于实验计划，当使用3%/3 mm伽马通过率标准时，三维伽马指数平均值超过98.0%，无统计学显著差异。