容积调强与动态调强在宫颈癌术后放射治疗中的剂量学研究

Dosimetric study of volumetric modulated arc therapy and intensity modulated radiation therapy in postoperative radiotherapy of cervical carcinoma

目的探讨容积调强(VMAT)与动态调强(IMRT)在宫颈癌术后放射治疗中的剂量学差异及治疗特点。方法选取35例宫颈癌手术患者,经过靶区和危及器官组织勾画后,分别设计VMAT和IMRT两种照射技术的放疗计划,观察两种放疗技术的计划靶体积剂量和危及器官的剂量学差异,并比较其机器跳数(MU)、治疗时间及体位误差。结果 VMAT治疗计划适形度指数(CI)明显高于IMRT计划(P<0.01);危及器官的剂量V30、V40和最大剂量VMAT计划均低于IMRT计划(P<0.05或P<0.01);VMAT技术的MU少于IMRT计划,治疗时间短于IMRT计划(P<0.01);两者的体位误差有明显差异,存在统计学意义(P<0.01)。结论宫颈癌患者术后放疗采用VMAT技术具有调强放疗的剂量学优点,且显著减少MU和总治疗时间,同时减小了体位误差,极大地提高了治疗的位置精度。但其临床疗效尚需进一步验证。

Objective To explore the dosimetric difference and treatment features of volumetric modulated arc therapy（ VMAT） and intensity modulated radiation therapy（ IMRT） in postoperative radiotherapy of cervical carcinoma surgery. Methods Thirty- five patients with cervical carcinoma surgery were selected and performed with VMAT and IMRT respectively after sketching the target and the organs at risk. The difference of doses of planning target volume（ PTV） and organs at risk of two kinds of radiation technology were observed,and the monitor unit（ MU）,treatment time and position error were compared. Results The conformity index（ CI） in PTV is obviously higher for VMAT than for IMRT（ P〈0. 01）; and V30,V40 and other dosimetric indicators in organs at risk are lower for VMAT than for IMRT（ P〈0. 05 or P〈0. 01）. The MU was less for VMAT than for IMRT and the treatment time was shorter for VMAT than for IMRT. The position error had visible difference between VMAT and IMRT（ P〈0. 01）. Conclusion For patients with postoperative radiotherapy of cervical carcinoma,VMAT has dosimetric advantages,reduces the MU,treatment time and position error,and improve the positional accuracy. However,the clinical efficacy needs to be further verified.