胸腺肿瘤常规适形与调强放疗的剂量学比较

Dosimetric Comparison of Conformal and Intensity Modulated Radiotherapy for the Patients with Thymoma and Thymic Carcinoma

目的:探讨分别应用常规适形CRT与调强放疗技术IMRT治疗胸腺肿瘤的剂量分布优劣。材料与方法:选取8例胸腺肿瘤患者,分别制作适形与调强计划,所有计划均给予60Gy和70Gy两种处方剂量。对于计划的剂量体积直方图(DVH)、计划靶区(PTV)的靶区适形指数(CI)和靶区均匀指数(HI)以及正常组织的最大或最小剂量等指标进行分析。结果:调强计划的计划靶区CI及HI指数为0.77和1.04,适形计划为0.52和1.13。调强计划对于肺、脊髓、食道、气管、心脏和胸骨这些正常组织均显示出更好的保护效果。调强计划的肺V20和平均剂量为15.6%和8.67Gy,适形计划为18.8%和9.62Gy;调强计划的脊髓D1%为37.42Gy,适形计划为44.05Gy;调强计划的气管V30和平均剂量为32.61%和21.24Gy,适形计划为43.00%和24.73Gy;调强计划的食道V50和平均剂量为9.04%和21.74Gy,适形计划为18.96%和24.32Gy;调强计划的心脏V40和平均剂量为11.16%和11.29Gy,适形计划为13.93%和11.47Gy;调强计划的胸骨最大剂量和平均剂量为65.38Gy和43.50Gy,适形计划为68.96Gy和47.03Gy。结论:调强计划能够在提高靶区适形度和均匀性的同时,降低正常器官受量。

Objective： To evaluate the optimized conformal and IMRT plans for the patients with thymoma and thymic carcino- ma. Methods： For 8 patients with thymoma and thymic carcinoma, CRT and IMRT planning were preformed. Target doses for plans were 60 and 70 Gy. Plans were compared according to dose-volume histogram （DVH） analysis including conformity and homogeneity indices （CI and H/） of planning target volumes （PTVs）, and maximum or mean doses to normal structures. Re- suits： CIs and His for IMRT plans were 0.77 and 1.04 while CRT 0.52 and 1.13. IMRT plans resulted in a better normal tissue sparing to Lung, Spinal Cord, Esophagus, Trachea, Heart and Stemal bone. V20 and Mean Dose of Lung were 15.6% and 8.67Gy （IMRT） vs. 18.8% and 9.62 Gy（CRT）; Din of Spinal cord was 37.42（IMRT） vs. 44.05（CRT）; V30 and Mean Dose of Trachea were 32.61% and 21.24 Gy （IMRT） vs. 43.00% and 24.73 Gy （CRT）; Vs0 and Mean Dose of Esophagus were 9.04% and 21.74 Gy （IMRT） vs. 18.96% and 24.32 Gy（CRT）; V4o and Mean Dose of Heart were 11.16% and 11.29 Gy （IMRT） vs. 13.93% arkl 11.47 Gy （CRT）; Dmax and Mean Dose of provides superior target volume coverage and conformality, with de- creased dose to normal structures.