食管癌三维适形和调强放疗剂量学对比研究

摘要

目的 应用三维治疗计划系统分析食管癌三维适形放疗(3 D-CRT)及调强放疗(IMRT)中肿瘤靶区和危及器官的剂量分布.方法 对20例胸段食管鳞癌患者行CT模拟定位.每例分别设计3D-CRT和IMRT两份计划,以95％ PTV60体积获得60Gy处方剂量进行归一,分析靶区剂量和危及器官受量.结果 IMRT的PTV50剂量参数D100和D95、PTV50体积参数V100均优于3D-CRT计划(P均＜0.01),PTV50剂量参数最大剂量、最小剂量和平均剂量均优于3D-CRT计划(P均＜0.01).IMRT的PTV60参数D100、D95、V100较3D-CRT无优势,Dmean低于3D-CRT(P ＜0.01).IMRT的PTV50和PTV60适形指数均优于3D-CRT(P均＜0.01).IMRT的全肺V5、V10、V15、V20和平均剂量均低于3D-CRT(P均＜0.01).IMRT和3D-CRT的心脏平均剂量相似,IMRT的脊髓剂量较3D-CRT显著增加,但未超过耐受量.结论 IMRT放疗技术能够更好实现食管癌的肿瘤靶区均匀的剂量分布,并降低肺部的照射剂量.%Objective To evaluate the dose distribution between three dimensional conformal radiotherapy(3D-CRT) and intensity modulated radiotherapy( IMRT) in tumor target area and organs at risks. Methods Twenty patients with thoracic esophageal carcinoma underwent CT simulation. The IMRT plan and 3D-CRT plan were designed for each patient. The prescription dose in 95% of PTV volume was 60 Gy. PTV and organs at risk in 3-DCRT and IMRT plans were compared. Results Dose parameters of PTV50 of IMRT plan was superior than those of 3DCRT( P <0.01). The volume parameters V100 of PTV50 of IMRT plan was higher than those of 3DCRT plan. Dose and volume parameters of PTV60 were similar between the 3DCRT plan and IMRT plan. The mean dose of PTV60 of IMRT plan was lower than that of 3DCRT plan(P <0. 01) . The conformity indexes of PTV50 and PTV60 in the IMRT plan were higher than those in 3DCRT plan. The V5 , V10, V15 , V20 of the total lung in the IMRT plan were all lower than those in the 3D-CRT plan( P < 0. 01). The maximum dose of spinal cord of IMRT plan was higher than that of 3D-CRT plan; the mean heart dose was similar. But the doses of spinal cord and heart were limited in tolerant range. Conclusion Considering the target conformal degree and target dose,IMRT is superior to 3D-CRT. Additionally, it can reduce the exposure dose of the lung.