螺旋断层放疗与常规调强放疗在乳腺癌保乳术后同步推量中的剂量学比较

目的 比较乳腺癌保乳术后同步推量放疗中应用常规调强放疗（IMRT）及螺旋断层放疗（HT）剂量分布的差异，为HT在乳腺癌保乳术后的临床应用提供依据。方法 随机选择10例乳腺癌保乳术后患者，统一勾画计划靶区（PTV）与原发灶靶区（PGTV）并导入HT计划系统及瓦里安Eclipse计划系统，分别设计IMRT和HT计划，处方剂量均为PTV 50Gy／25f、PGTV 60Gy／25f，通过比较靶区剂量适形度、均匀性以及心肺受照剂量来评估IMRT与HT的优劣。结果 HT计划中靶区剂量的均匀性、适形度明显优于IMRT（P＜0.05），患侧肺V5、V10、V20、V30及肺平均剂量均明显低于IMRT（P＜0.05），但健侧肺V5增加；心脏剂量明显降低（P＜0.05）。结论 对于乳腺癌保乳术后同步推量放疗，HT与IMRT计划都可以满足临床剂量的要求，但HT计划在剂量学方面相对于IMRT计划具有优势，可以显著降低对正常器官的毒副作用。

A dosimetric comparison on helical tomotherapy and IMRT after breast-conserving therapy for breast cancer

Objective To study the difference in dosimetric characteristics and protection of organs at risk （OAR） between helical tomotherapy（HT） and routine intensity modulated radiation therapy（IMRT） for breast cancer patients after breast-conserving therapy. Methods CT images of 10 breast cancer patients after breast-conserving therapy were delineated and transmitted to HT plan- ning and Yarian Eclipse systems. Planning target volume（PTV） and primary lesion（PGTV） were contoured on CT slices of each pa- tient. Prescribed dose for PTV was 50Gy/25f, while dose for PGTV was boosted to 60Gy/25f. Homogeneity index （ HI）, conformity number（ CN）, isodose line and dose volume histogram（DVH） were used to evaluate the dose distribution in tumor and OARs. Results The dose distribution HI and CN of HT plan were better than those of IMRT（ P 〈 0. 05 ）. Compared with IMRT, HT notably reduced the volume of ipsilateral lung at 5,10,20 and 30Gy（P 〈 0.05 ）. The mean dose of whole lung also was reduced（ P 〈 0. 05 ）. But the volume of contralateral lung at 5Gy was increased in HT. The HT plan was better for the protection of heart in patients with over than the IMRT（P 〈 0. 05）. Conclusion The two treatment modalities can satisfy clinical requirements. HT has a better dose distribution and protective effect for OARs than IMRT.