CRT+IMRT混合调强与IMRT技术在乳腺癌放疗计划的剂量学比较研究

Dosimetric comparison of CRT+IMRT hybrid intensity-modulated radiation therapy and IMRT technique in radiotherapy planning for breast cancer

目的探讨适形放疗(CRT)+固定野调强放疗(IMRT)混合调强(HyIMRT)技术与IMRT技术在乳腺癌根治术后放疗计划的剂量学差异。方法选取湘雅常德医院2019-2020年收治的左乳腺癌(10例)和右乳腺癌(10例)根治术后患者的CT图像,对患侧胸壁、内乳淋巴结区域及锁骨上淋巴结区域进行统一勾画,针对每例患者的CT图像分别设计HyIMRT计划与改进后的IMRT计划。比较计划靶区(PTV)和危及器官(OAR)相关剂量学参数,并使用Bland-Altman方法绘制两种计划方案的均值-差值散点图,判断两种计划方案的一致性。结果两种计划乳腺癌PTV相关参数仅右乳98%靶区体积受到的照射剂量(D98)、适形指数(CI)有明显差异(P<0.05),HyIMRT计划高于IMRT计划,其余参数均无明显差异(P>0.05)。左乳腺癌患者:相较于IMRT计划,HyIMRT计划在右肺、双肺5 Gy剂量所包绕的体积(V5)及右乳平均照射剂量(Dmean)和5%乳腺体积受到的照射剂量(D5)存在一定优势(P<0.05);右乳腺癌患者:相较于IMRT计划,HyIMRT计划在左肺、双肺V5,心脏Dmean及左乳Dmean和D5存在一定优势(P<0.05)。两种计划方案的测试数据点几乎都落在95%一致性区间内。结论两种计划在乳腺癌术后放疗中一致性较好,都从计划设计层面考虑了呼吸运动的影响,能够为乳腺癌临床计划设计提供支持。

Objective To investigate the dosimetry differences between conformal therapy(CRT)and intensity modulated radiation therapy(IMRT)combined hybrid intensity-modulated radiation therapy(Hy-IMRT)and IMRT technique in radiotherapy planning for post-radical mastectomy.Methods CT images of left breast cancer patients(10 cases)and right breast cancer patients(10 cases)after radical mastectomy admitted to Xiangya Changde Hospital from 2019 to 2020 were selected.The chest wall of the affected side,the internal breast lymph node area and the supraclavicular lymph node area were uniformly delineated.According to the CT images of each patient,the HyIMRT plan and improved IMRT plan were designed respectively.Relevant dosimetric parameters of the planning target volume(PTV)and organ at risk(OAR)were compared,and the Bland-Altman method was used to draw the mean-difference scatter plots of the two plans,in order to determine the consistency of the two plans.Results Among the related breast cancer target parameters,only 98%target volume irradiation dose(D98)and conformal index(CI)of the right breast cancer were statistically different between the two plans(P<0.05).D98 and CI in HyIMRT plan were higher than those in IMRT plan,while the other parameters were not statistically different(P>0.05).The left breast cancer:compared with the IMRT plan,the HyIMRT plan had some advantages in the right lung and double lungs volume wrapped by the 5 Gy dose(V5),mean irradiation dose(Dmean)of the right breast and 5%breast volume irradiation dose(D5).The right breast cancer:compared with the IMRT plan,the HyIMRT plan had some advantages in the left lung and double lungs V5,the heart Dmean,the left breast Dmean and D5.The test results for both plans were almost within the 95%consistency interval.Conclusion The two plans are well consistent in postoperative radiotherapy for breast cancer,and both consider the effects of respiratory movement from the planning design level,and can provide support for the design of clinical planning for breast cancer.