胸段食管癌病变上扩张食管在放疗期间靶区范围及周围危及器官剂量与体积变化情况分析

Analysis of target volume and volume changes of target organs and surrounding organs at risk in patients with thoracic esophageal carcinoma and dilated upper esophagus during radiotherapy

目的分析胸段食管癌病变上扩张食管在放疗期间靶区范围和周围危及器官剂量、体积的变化情况。方法收集125例未进行手术和放疗的胸段食管癌患者的临床资料。对125例患者放疗复位时观察其计划靶体积(PTV)和大体肿瘤体积(GTV)的变化情况,复制放疗前制定的放射治疗计划到复位CT图像上,比较周围危及器官和靶区范围在杂交计划和复位计划中的剂量变化。结果患者放疗复位时GTV平均体积、食管狭窄率、食管病灶上方扩张最小横径、食管病灶上方扩张最大横径、复位GTV体积/初始GTV体积均小于放疗前,差异有统计学意义(P﹤0.05);PTV体积在复位计划(CT2/Plan2)中大于杂交计划(CT2/Plan1),而双肺平均剂量、脊髓平均最大剂量、双肺受照体积在复位计划中小于杂交计划,差异均有统计学意义(P﹤0.05)。结论在实施食管癌放疗过程中,食管形态的变化可以导致肺和脊髓等危及器官的受照体积、剂量与放疗前明显不同,进而影响放疗的精准度。

Objective To evaluate the target volume and volume changes of target organs and surrounding organs at risk in patients with thoracic esophageal carcinoma and dilated upper esophagus.Method The clinical data of 125 cases of thoracic esophageal carcinoma that were not treated with surgery or radiotherapy were collected.The changes of planned target volume（PTV） and gross target volume（GTV） during repositioning of radiotherapy in 125 patients were observed,and then the prior radiation strategy were duplicated on the repositioned CT images to compare the dose change of surrounding organs at risk and target volume in hybrid plan and reposition plan.Result The average GTV,rate of esophageal stricture,the minimum and maximum diameter above dilated upper esophagus,ratio of repositioned GTV volume/initial GTV were decreased during radiation repositioning as compared with that before radiation,the differences were statistically significant（P〈0.05）; PTV was greater in reposition plan（CT2/Plan2） than in hybrid plan（CT2/Plan1）,while the average dose of both lungs,average maximum dose of spinal cord,exposure volume in both lungs were all lower in reposition plan than in hybrid plan,with significant differences observed（P〈0.05）.Conclusion During the application of radiotherapy for esophageal carcinoma,the morphological change of esophagus can influence the exposure volume,dose of lungs,spinal cord and other organs at risk,resulting in significant different volume compared with that before radiation,thus compromising the accuracy of the radiotherapy.