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目的用三维适形治疗计划系统分析60Coγ线照射条件下,食管癌三维适形放疗中的危险器官—脊髓受照量,包括最大剂量和体积剂量情况,以探索与脊髓损伤有关的潜在因素。方法25例食管癌患者,经体位固定、CT-模拟机采集靶区图像信息、由局域网传输至治疗计划系统工作站(Pinnacle36.2 b),进行虚拟透视和模拟,获得优化的三维计划。然后,用计划之DVH曲线分析脊髓受照量与各治疗参数和食管的95%PTV剂量的关系。结果脊髓受照量V40、V45的中位数分别为5.70%(0~9.38%)和0(0~2.08%);有6例患者的最大脊髓受量超过50 Gy,最大V50为3.8%;食管的95%PTV剂量最小60 Gy,最大72 Gy。脊髓受照射量V40与PTVD100呈正相关,V45与PTVD100呈正相关;而与射野数量、角度、修饰,分割次数,归一点剂量,CTVD95、CTVD100、GTVD100无明显相关。全部患者随访4年以上,无一例被检出放射性脊髓病。结论60Coγ线用于食管癌三维适形放疗,在很好的满足和(或)提高靶区剂量要求的前提下,脊髓的受照量可得到很好的控制,V50≤3.8%时是安全的,但要注意控制PTV体积及剂量;脊髓的受量可能要比掌握的高。
OBJECTIVE: To investigate the potential dose of radiation-induced spinal cord injury in esophageal cancer under three-dimensional conformal radiotherapy (60Coγ-ray irradiation), including maximum dose and volume dose, to explore potential factors related to spinal cord injury. Methods Twenty-five patients with esophageal cancer were enrolled in a fixed-position, CT-simulator to acquire the target area image information, which was transmitted to Pinnacle 36.2 b via the local area network for virtual perspective and simulation to obtain an optimized three-dimensional plan. The projected DVH curve was then used to analyze the relationship between spinal cord exposure and the 95% PTV dose for each treatment parameter and esophagus. Results The median spinal cord irradiation doses of V40 and V45 were 5.70% (0- 9.38%) and 0 (0-2.08%) respectively. Six patients had the largest spinal cord volume exceeding 50 Gy and the maximum V50 was 3.8%. The minimum dose of 95% PTV for the esophagus is 60 Gy, with a maximum of 72 Gy. Spinal cord irradiation V40 was positively correlated with PTVD100, V45 and PTVD100 was positively correlated; but not with the number of field, angle, modification, the number of divisions, at the dose, CTVD95, CTVD100, GTVD100 no significant correlation. All patients were followed up for more than 4 years, and none of them were detected with radioactive myelopathy. Conclusions The 60Coγ line is suitable for three-dimensional conformal radiotherapy of esophageal cancer. Under the premise of meeting the requirements of target volume and / or dose well, the amount of irradiation of the spinal cord can be well controlled. When V50≤3.8%, it is safe , But pay attention to control PTV volume and dose; spinal cord by the amount may be higher than the master.