Dosimetry of organs at risk between involved field radiation and extended field radiation in patients with thoracic esophageal cancer

Abstract

Objective To study the irradiation dose of organs at risk (OAR) in involved field radiation and extended field radiation in patients with thoracic esophageal cancer who received intensity modulated radiotherapy (IMRT).

Methods A total of 40 patients with thoracic esophageal cancer were treated with IMRT. The involved field, extended field, and OAR were outlined to generate IMRT plans. The conformity index ( CI) and homogeneity index ( HI) of planning target volume (PTV) and the irradiation parameters of OAR were evaluated for the two plans. Paired t-test was used for comparison of irradiation parameters.

Results The PTV of both plans received the prescribed dose. There were no significant differences in CI and HI of PTV between the two groups ( P = 0.317, 0.130). There were significant differences in average lung dose, lung V ₅, lung V ₂₀, lung V ₃₀, spinal cord D _mean, heart D _mean, heart D _max, heart V ₃₀, heart V ₄₀, and heart V ₆₀ between the two groups ( P < 0.01).

Conclusion Compared with the extended field, the involved field can reduce the irradiation dose of ORA in patients with thoracic esophageal cancer, thus reducing the risk of radiation.

Abstract

摘要： 目的 研宄胸段食管癌逆向调强放射治疗 (IMRT) 中累及野照射与扩大野照射对危及器官 (OAR) 受照剂量的 影响。 方法 40 例胸段食管癌患者分别行累及野靶区勾画和扩大野靶区勾画并勾画危及器官, 制定 IMRT 计划, 评 估 2 个计划的靶区适形指数 ( CI) 和均匀性指数 ( HI) 及危及器官的剂量学参数, 剂量学参数比较采用配对 t 检验。 结果 2 种计划的 PTV 均能满足处方剂量要求, PTV 在 CI、 HI 上相近 ( P = 0.317、0.130)。两组间平均肺剂量、两肺 V ₅、两肺 V ₂₀、两肺 V ₃₀、脊髓 D _mean、心脏 D _mean、心脏 D _max、心脏 V ₃₀、心脏 V ₄₀、心脏 V ₆₀ 差异均存在统计学意义 ( P < 0.01)。 结论 胸段食管癌患者行累及野照射与扩大野比较, 可降低正常器官的受照剂量, 从而降低放射性损伤风险。