腹部肿瘤患者放疗行图像引导对剂量误差纠正的有效性研究

Study on effectiveness of radiotherapy line image guidance for dose-error correction in patients with abdominal tumor

目的:探讨腹部肿瘤通过锥形束CT扫描纠正摆位误差后对治疗剂量实施的准确性影响,以对临床放疗提供指导。方法:采用双盲法选取6例腹部肿瘤患者,每次治疗时利用电子射野影像装置(electronical portal imaging device,EPID)采集剂量学信息,利用EDOSE工具进行三维剂量重建,对患者的治疗计划完成实时三维剂量验证。每例患者行图像引导与未行图像引导各采集5组数据,共60组数据,比较图像引导后再治疗与直接治疗2种情况下实时三维剂量验证的结果。结果:治疗前锥形束CT图像引导能够在一定程度上纠正摆位误差,但总体γ通过率与未行图像引导相比并未体现出优势,患者靶区的覆盖率亦没有提高,正常组织受量方面也没有明显优势。结论:对于腹部肿瘤患者,现行的按照骨性标记来配准的图像引导纠正摆位误差后,患者治疗过程中三维剂量验证结果没有得到明显改善,治疗剂量实施准确性没有得到明显提高。

Objective To investigate the effect of the correction of the position error of the abdominal tumor by cone beamscanning. Six patients with abdominal tumor were selected with double -blind method, and electronical portalimaing device was used to collect the information of the patient dosimetry during radiotherapy. EDOSE tool was applied to 3Ddose reconstruction so as to execute real-time 3D dose verification of the treatment plan. Each patient had 5 sets of dataacquired when image guidance existed and another 5 sets when image guidance was absent. The treatment effects with orwithout image guidance were compared. The overall 酌 passing rate with cone beam CT image guidance gained noadvantages over that without image guidance, though the setup error was corrected to some extent. Image guidancecontributed nothing to increasing target area coverage while decreasing exposure dose to normal tissue. Setuperror correction by the image guidance based on bone marker has no significant effect on improving 3D dose verification anddose accuracy during the radiotherapy of the abdominal tumor patient.