【摘要】 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。更多还原

【Abstract】 Objective To analyse the volume-dosage and maximal normalization-dosage that received by spinal cord from external cobalt-60 using 3-dimensional conformal treatment planning system(TPS),so as to find potential factor related to radiation myelopathy.Methods Twenty-five patients with esophageal carcinoma were analysed.All patients were firstly immobilized in fixation devices and simulated under the CT-simulator in treatment position.Digital images were obtained by CT-scanning,and then transferred through local network to the TPS station(Pinnacle3 6.2b) where the virtual fluoroscopy and simulation were performed.Dosage(i.e.maximum-dosage V40 V45 V50)received by spinal cord and therapy parameters(i.e.PTVD95 PTVD100 CTVD95 CTVD100 GTVD100,dosage of 95% PTV,portal quantity,Gantry angle,portal compensator-wedge,fractionation,focal lesion location and length etc.)were analysed,the relations between them were assessed with DVH graph.Results The median dosages received by spinal cord were 5.70%(0-9.38%) and 0(0-2.08%) for V40 and V45 respectively.V50 was found in six of them and its maxium was 3.8%.The minimum and maximum dosages of 95% PTV for primary esophageal disease were 60 Gy and 72 Gy respectively.Positive correlations existed between PTVD100 and V40 and between PTVD100 and V45.No correlation was found between other parameters and spinal cord volume-dosage.All patients were followed up for longer than four years.No myelopathy was observed in these patients.Conclusion The risk of myelopathy does not increase in 3-dimensional conformal radiotherapy of esophageal carcinoma with external cobalt-60 γ-irradiation if primary esophageal disease dosage requirement of 95% PTV is fully and well fulfilled.It is safe for spinal cord when V50 is 3.8%,but attention should be paid to control dosage and margin of PTV.The radiation tolerance of spinal cord may be higher than present criterion.更多还原