Vandecasteele Katrien, De Neve Wilfried, De Gersem Werner, Delrue Louke, Paelinck Leen, Makar Amin, Fonteyne Valérie, De Wagter Carlos, Villeirs Geert, De Meerleer Gert
Department of Radiotherapy, Ghent University Hospital, Ghent, Belgium.
Strahlenther Onkol. 2009 Dec;185(12):799-807. doi: 10.1007/s00066-009-1986-8.
To report on the planning procedure, quality control, and clinical implementation of intensity-modulated arc therapy (IMAT) delivering a simultaneous integrated boost (SIB) in patients with primary irresectable cervix carcinoma.
Six patients underwent PET-CT (positron emission tomography-computed tomography) and MRI (magnetic resonance imaging) before treatment planning. Prescription (25 fractions) was (1) a median dose (D(50)) of 62, 58 and 56 Gy to the primary tumor (GTV_cervix), primary clinical target volume (CTV_cervix) and its planning target volume (PTV_cervix), respectively; (2) a D(50) of 60 Gy to the PET-positive lymph nodes (GTV_nodes); (3) a minimal dose (D(98)) of 45 Gy to the planning target volume of the elective lymph nodes (PTV_nodes). IMAT plans were generated using an anatomy-based exclusion tool with the aid of weight and leaf position optimization. The dosimetric delivery of IMAT was validated preclinically using radiochromic film dosimetry.
Five to nine arcs were needed to create valid IMAT plans. Dose constraints on D(50) were not met in two patients (both GTV_cervix: 1 Gy and 3 Gy less). D(98) for PTV_nodes was not met in three patients (1 Gy each). Film dosimetry showed excellent gamma evaluation. There were no treatment interruptions.
IMAT allows delivering an SIB to the macroscopic tumor without compromising the dose to the elective lymph nodes or the organs at risk. The clinical implementation is feasible.
报告在原发性不可切除宫颈癌患者中实施调强弧形放疗（IMAT）同步整合加量（SIB）的计划制定程序、质量控制和临床应用情况。
6例患者在治疗计划制定前接受了正电子发射断层扫描-计算机断层扫描（PET-CT）和磁共振成像（MRI）检查。处方剂量（25次分割）为：（1）分别给予原发肿瘤（GTV_宫颈）、原发临床靶区（CTV_宫颈）及其计划靶区（PTV_宫颈）的中位剂量（D(50)）62 Gy、58 Gy和56 Gy；（2）给予PET阳性淋巴结（GTV_淋巴结）的D(50)为60 Gy；（3）给予选择性淋巴结计划靶区（PTV_淋巴结）的最小剂量（D(98)）为45 Gy。IMAT计划借助基于解剖结构的排除工具并通过权重和叶片位置优化生成。IMAT的剂量学输出在临床前使用放射变色薄膜剂量测定法进行了验证。
生成有效的IMAT计划需要5至9个弧形照射野。2例患者未达到D(50)的剂量限制（GTV_宫颈均低1 Gy和3 Gy）。3例患者未达到PTV_淋巴结的D(98)（均低1 Gy）。薄膜剂量测定法显示伽马评估结果优异。无治疗中断情况。
IMAT能够在不影响选择性淋巴结或危及器官剂量的情况下，对肉眼可见肿瘤进行SIB照射。临床应用是可行的。
