胸段食管癌VMAT计划的剂量学验证研究

目的 探讨VMAT计划在胸段食管癌放疗中的适应性。方法 应用0.6 cm³指形电离室和COMPASS三维剂量验证系统分别对 10例胸上段、10例胸中段食管癌的VMAT计划进行绝对剂量和相对剂量的验证。应用DVH比较靶区、肺、心脏和脊髓受照剂量和体积差异,并分析GTV、CTV、PTV和OAR的γ通过率。结果 胸上、中段食管癌的等中心处绝对剂量精确度均≥99%,GTV、PTV和OAR的γ通过率均≥97%。胸上段食管癌GTV、CTV、PTV的 D_95%、D_mean的验证差异均≤3%,脊髓 D_1%差异为2.21%,左肺和右肺的 V₅~V₃₀、D_mean的差异≤2%。胸中段食管癌的GTV、CTV、PTV和OAR的 D_95%、D_mean的验证差异≤2%,脊髓 D_1%差异为2.04%。左肺和右肺的 V₅~V₃₀以 V₁₀为界差异呈逐渐增大的趋势,处于1.5%以内。心脏 D_mean的差异为2.68%。结论 VMAT技术在胸段食管癌放疗中是适用的。

Study on dosimetric verification of VMAT treatment planning for chest esophageal carcinoma

Objective To study the dosimetry characteristics of VMAT plan in the esophageal carcinoma radiotherapy. Methods Application of 0.6 cm³ ionization chamber and COMPASS three-dimensional dose verification system, 20 cases of upper and middle chest esophageal carcinoma on the VMAT plans for absolute dose and relative dose verification. Dose volume histogram (DVH) comparison treatment target, lungs, heart, and differences in the spinal cord irradiation dose and volume, and analyses γ pass rate of GTV, CTV, PTV and organs at risks. Results The center dose of upper and middle chest esophageal carcinoma accurate rates were above 99%. Thoracic segment esophageal:GTV, PTV and organs at risks of γ pass rate above 97%. D_95% and D_mean of GTV, CTV and PTV were relatively undervalued within 3%. D_1% of spinal cord is 2.21% overvalued. Left and right pulmonary V₅ were slightly overvalued by about 0.5%, V₁₀—D₃₀, D_mean undervalued within 2%. In period of middle chest esophageal carcinoma:the gamma passed rate of GTV, CTV, PTV and organs at risks of above 97%, GTV, CTV, PTV D_95%, D_mean were relatively undervalued within 2%. Spinal cord D_1% is 2.04% overvalued. Left and right pulmonary V₅—D₃₀ to V₁₀ as a trend of gradually to be underestimated, at 1.5%. Heart D_mean was undervalued by 2.68%. Conclusion VMAT technology is applicable in the chest esophageal carcinoma radiotherapy.