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目的比较前列腺癌重碳离子放疗(C-ion RT)与调强放疗(IMRT)在剂量学方面的差异。方法随机选取5例前列腺癌患者,分别设计4野共面的C-ion RT计划和7野共面的IMRT计划。剂量均采用百分剂量,95%的等剂量面必须包括100%的计划靶体积(PTV)。比较靶区剂量分布的适形度指数(CI)和异质性指数(IC),根据剂量体积直方图(DVH),比较相同剂量水平下C-ion RT计划与IMRT计划中周围器官及非靶区正常组织的照射体积。结果在C-ion RT计划中,CI_(50%)、CI_(95%)、IC分别为3．36、1．20和0．03,与IMRT计划比较差异有统计学意义(P均＜0．01),靶区剂量分布的CI和IC均优于IMRT计划。除了95%的剂量水平外,在10%、30%、50%、70%和90%剂量水平,采用C-ion RT均可明显减少直肠的受照射体积(P均＜0．05),同时完全保护直肠的后壁；在任何剂量水平,C-ion RT可明显减少膀胱和非靶区正常组织的受照射体积(P均＜0．05)；在10%、20%、30%和40%剂量水平,C-ion RT可明显减少双侧股骨头的受照射体积(P均＜0．05)。结论在前列腺癌的放射治疗中,与IMRT计划相比,C-ion RT计划在剂量学方面有明显优势,C-ion RT的这些优势将能够进一步提高前列腺癌的局部控制率,减少放疗引起的并发症。
Objective To compare the dosimetric differences between C-ion RT and IMRT in prostate cancer. Methods Five patients with prostate cancer were randomly selected, and four co-planar C-ion RT plans and seven wild coplanar IMRT plans were designed. The doses are in percentage and the 95% isodose must include 100% of the planned target volume (PTV). According to dose-volume histogram (DVH), the C-ion RT plan and IMRT plan were compared between the surrounding organs and non-target at the same dose level, and the concentricity index (CI) and heterogeneity index District normal tissue irradiation volume. Results CI-50%, CI 95% and IC were 3.36, 1.20 and 0.03, respectively, in the C-ion RT plan, with statistical significance compared with the IMRT plan (all P <0 .01), CI and IC of target dose distribution were better than IMRT plan. In addition to the 95% dose level, C-ion RT significantly reduced rectal irradiated volume (P <0.05) at 10%, 30%, 50%, 70% and 90% Completely protected the posterior wall of the rectum; C-ion RT significantly decreased the irradiated volume of normal and non-target tissues at any dose level (all P <0.05); at 10%, 20%, 30% and 40% % Dose level, C-ion RT can significantly reduce the irradiated volume of bilateral femoral head (all P <0.05). Conclusions C-ion RT programs have distinct advantages in dosimetry over IMRT in radiation therapy for prostate cancer and these advantages of C-ion RT will further improve the local control of prostate cancer and reduce the risk of radiotherapy complication.