分次内和分次间摆位误差在宫颈自适应放疗中的研究

摘要

Objective:Evaluate the intra -and inter -fractional set -up errors through a course of IGRT(image-guided adaptive radiotherapy)for cervical cancer patients.Methods:To select 16 patients with cervical cancer from January to September in 2014 diagnosed with IIb -IIIb ,all patients that without operation were treated with IGRT as radical treatment.Every patient had 10 times 20 CBCT scanning images before and after each radiotherapy.In order to obtain 3D orientation vector errors,these images were blended into Plan CT with registration and fusion,symbolized by X(Lateral),Y(Anterior -posterior),Z(Vertical),CR(angles of rotation).Calculated the average and standard devi-ation of set -up errors.Results:A collection of 320 sets of CBCT images,every patient approximately had 20 sets of image,the select of CBCT scanning images show:The intra -fractional set -up errorsin the direction of lateral,verti-cal,anterior -posterior respectively were(0.11 ±0.14)cm,(0.17 ±0.18)cm,(0.20 ±0.19)cm;The inter -frac-tional set -up errors in the direction of lateral,vertical,anterior -posterior respectively were (0.11 ±0.13cm), (0.17 ±0.20)cm,(0.25 ±0.20)cm.Conclusion:During image -guided adaptive radiotherapy,the average of set -up errorsapproximately 0.15cm in any given direction,this wide range of error should be accounted during external beam radiation.%目的：在图像引导的自适应放疗中，评估宫颈癌患者分次内、分次间的摆位误差。方法：从2014年1月至9月选取16例诊断为 IIb －IIIb 期的宫颈癌患者，所有病人均未行手术治疗，而是采用三维调强放疗作为根治性治疗。每个病人在放疗前后行10次20个 CBCT 扫描图像，与计划 CT 进行配准融合，得到三维方向矢量误差，用 X（左右）、Y（腹背）、Z（头脚）、CR（旋转角度）表示。计算摆位误差的平均变化及标准差。结果：收集320套 CBCT 图像，每个病人平均20套。所选 CBCT 扫描图像显示：患者在左右、头脚、腹背方向的分次内摆位误差分别为（0．11±0．14）cm、（0．17±0．18）cm、（0．20±0．19）cm；在左右、头脚、腹背方向的分次间摆位误差分别为（0．11±0．13）cm、（0．17±0．20）cm、（0．25±0．20）cm。结论：在图像引导的自适应放疗中，患者在各个方向的摆位误差均数为0．15cm，这一大幅度的误差需要在放疗中被考虑到。