图像引导宫颈癌体外自适应放疗的剂量学研究

Dosimetric study of adaptive external beam radiotherapy for cervical carcinoma

收集6例符合治疗指征的宫颈癌患者,采用西门子的Artiste自适应放疗系统行适形调强放疗,分别于治疗前、8次治疗后、16次治疗后进行图像采集并重新勾画靶区,制定新的计划,分别比较3组计划间靶区与危及器官的剂量学差异与位置变化。结果显示在放疗过程中,治疗靶区体积逐渐缩小,3组计划的靶区剂量差异无统计学意义;膀胱、直肠位置变化较大,其中以头脚方向最为明显;膀胱、直肠的V40、V45、V50在3组计划中依次减少且差异均有统计学意义(P<0.05)。结果表明宫颈癌体外离线式自适应放疗可根据图像反馈信息调整计划,对治疗靶区影响较小,但对膀胱、直肠等重要正常器官组织的保护具有积极意义。

6 patients with cervical carcinoma treated by the SIEMENS’s Artiste received totally 18 CT scans every 8 fractions, then we replanned and obtained the three groups named by IMRT, ART1 and ART2 based on these im-ages to compare these plans’ measure indexes of dosimetry and position. The average volume of CTV reduced dur-ing the course of treatment, the dose of CTV in the three groups was similar, and there was no significant differ-ence. Bladder and rectum’s positions changed a lot, especially in the superior and inferior directions, and the do-ses of these two organs reduced significantly （P 〈 0. 05） at three dose levels （V40 , V45 and V50 ）. The results show that the adaptive external beam radiotherapy for cervical carcinoma can adjust treatment planning depending on the feedback of scanning images, thus may not bring significant changes in targets, while on the other hand, still play a positive role in the protection of the organs at risk.