直肠癌放疗不同技术和体位对小肠受照剂量的影响

Effect of different techniques and position of rectal cancer radiotherapy on the dose of small intestine

目的探讨不同直肠癌放疗技术对小肠受照剂量的影响。方法选择2015年3月~2018年3月在我院诊断治疗的直肠癌患者31例为研究对象。所有患者照射方案包括俯卧位3D-CRT、仰卧位3D-CRT、俯卧位IMRT与仰卧位IMRT。比较两种治疗体位PTV、小肠、膀胱照射体积,比较相同治疗体位两种照射技术小肠受照体积及相同照射技术不同体位小肠受照体积。结果两组体位靶区PTV与小肠照射体积比较差异无统计学意义(P>0.05);俯卧位膀胱照射体积显著小于仰卧位,差异有统计学意义(P<0.05)。俯卧位3D-CRT放疗技术小肠V45受照体积显著高于IMRT,差异有统计学意义(P<0.05)。仰卧位3D-CRT放疗技术小肠V45受照体积显著高于IMRT,差异有统计学意义(P<0.05)。3D-CRT技术下仰卧位小肠V45显著高于俯卧位,差异有统计学意义(P<0.05)。IMRT放疗技术下仰卧位小肠V45显著高于俯卧位,差异有统计学意义(P<0.05)。结论相同的体位,IMRT相对于3DCRT小肠照射剂量更少,而相同的照射技术下,俯卧位小肠V45更小,提示俯卧位照射能够减少小肠的受照剂量。

Objective To investigate the effect of radiation therapy on the dose of small intestine in different rectal cancers. Methods 31 patients with rectal cancer diagnosed and treated in our hospital from March 2015 to March 2018 were selected as subjects. The exposure regimens of all patients included prone 3D-CRT, supine 3D-CRT, prone IMRT and supine IMRT. The two treatment positions PTV, small intestine and bladder irradiation volume were compared. The small intestine exposure volume by two irradiation techniques in the same treatment position was compared. And the small intestine exposure volume by the same irradiation technique in different body position was compared. Results There was no significant difference in body position target PTV and the exposure volume of small intestine between the two groups （P〉0.05）. The volume of bladder irradiation in the prone position was significantly smaller than that in the supine position, and the difference was statistically significant （P〈0.05）. In the prone position 3D-CRT radiotherapy technique, the small intestine V45 exposure volume was significantly higher than that of IMRT, and the difference was statistically significant（P〈0.05）. In the supine position 3D-CRT radiotherapy technique, the volume of small intestine V45 was significantly higher than that of IMRT, and the difference was statistically significant（P〈0.05）. Under the 3D- CRT technique, the V45 of the small intestine in the supine position was significantly higher than that in the prone position, and the difference was statistical]y significant （P〈0.05）. Under the IMRT radiotherapy technique, the V45 of the small intestine in the supine position was significantly higher than that in the prone position, and the difference was statistically significant（P〈0.05）. Conclusion In the same position, the dose of IMRT is less than that of the 3D-CRT in small intestine. Under the same irradiation technique, the dose of V45 in the prone position is smaller, suggesting that the prone position can reduce the exposure dose of the small intestine.