乳腺癌根治术后适形和调强混合放疗计划与单纯调强放疗计划的剂量学比较

摘要

Objective To compare the dosimetric distribution of Intensity Modulated Radiotherapy (IMRT) together with 3-Dimensional Conformal Radiation Therapy (3D-CRT) and simple IMRT for breast cancer after radical surgery in order to provide the basis for breast cancer radio therapy. Methods Altogether 20 breast cancer patients were collected. For each patient, the combination of IMRT and CRT as well as simple IMRT were designed with the prescription dose of 50 Gy /25 times so as to compare the dosimetric differences in Planning Target Volume (PTV) and Organs at Risk (OAR) of two plans. Results The PTV V95% of two plans were similar [(99.18±0.32)% and (99.43±0.47)% respectively] without statistically significant difference (P>0.05); V105% and V110% of IMRT together with 3D-CRT and simple IMRT were similar without statistically significant difference (P>0.05). Conformity Index (CI) and Homogeneity Index (HI) of combined plans were superior than those of simple IMRT, (P<0.05). In contrast with simple IMRT, ipsilateral lung V30, V20, V5 of combined plans were reduced by 2.68%, 3.25% and 27.38% respectively (P<0.05); cardiac V30, V40 and V50 were reduced by 3.18%, 2.27% and 1.52% respectively (P<0.05).Conclusion Compared with simple IMRT, combination of IMRT and 3D-CRT achieved better effects in dose distribution and CI and reduced the irradiation dose of lung, heart and other vital organs, which showed better application effects.%目的：比较乳腺癌根治术后适形（3-Dimensional Conformal Radiation Therapy，3D-CRT）和调强（Intensity Modulated Radiotherapy，IMRT）混合放疗与单纯IMRT的剂量学分布，为乳腺癌根治术后放疗方法的选择和应用提供依据。方法选取20例左乳腺癌根治术后患者，针对每个患者分别设计CRT和IMRT混合放疗计划与单纯IMRT计划，处方剂量均为50 Gy/25次，比较两种计划的靶区和危及器官的剂量学差异。结果两种计划中95%等剂量曲线包绕计划靶区的体积相似，分别为（99.18±0.32）%和（99.43±0.47）%，无显著差异（P＞0.05）；混合计划计划靶区的V105%、V110%值分别与单纯IMRT计划的对应值接近（P＞0.05）；混合计划的剂量适形度指数（Conformity Index，CI）、剂量均匀性指数（Homogeneity Index，HI）均优于单纯IMRT计划（P<0.05）。与单纯IMRT计划相比，混合计划患侧肺V30、V20、V5分别降低了2.68%、3.25%和27.38%，同时肺平均剂量（Mean Lung Dose，MLD）由10.21 Gy下降至8.35 Gy(P<0.05)；混合放疗计划心脏V30、V40和V50分别降低了3.18%、2.27%和1.52%（P<0.05）。结论与单纯IMRT计划相比，CRT和IMRT混合放疗计划在剂量分布及适形度方面效果更好，且降低了肺、心脏等重要器官的照射剂量，具有更好的应用效果。