宫颈癌术后放疗行限定骨盆IMRT计划剂量学分析

Dosimetric analysis of bone marrow-sparing pelvic intensity-modulated radiotherapy after surgery for cervical cancer

目的 探讨宫颈癌术后放疗行限定骨盆IMRT计划（BM-sparing IMRT）对靶区剂量、OAR以及血液不良反应的影响。方法 选取10例接受术后放疗的宫颈癌患者,通过瓦里安TPS对同一图像分别行BM-sparing IMRT和常规IMRT,比较2种计划中骨盆受量差异、靶区剂量分布以及其他OAR受量差异。选取30例既往接受术后放疗的宫颈癌患者,Pearson法分析骨盆受量与骨盆冠状轴、矢状轴、垂直轴长度与体积相关性。选取41例接受术后放疗的宫颈癌患者,随机分为观察组和对照组,观察组疗前行BM-sparing IMRT计划并按要求限定骨盆受量,对照组行常规IMRT;Logistic回归分析2个组患者≥2级血液不良反应发生与骨盆受量相关性。结果 BM-sparing IMRT与IMRT均能达到CTV剂量要求,OAR受量相近（P均〉0.05）。BM-sparing IMRT骨盆的Dmean、V10、V20、V40、V50均低于IMRT （P=0.003-0.045）。Pearson法相关分析结果显示骨盆的Dmean、V20、V30、V40、V50与骨盆冠状轴长呈负相关（P=0.008-0.038）。观察组患者的血液不良反应发生率明显低于对照组（P=0.019）。Logistic回归分析结果显示血液不良反应发生与骨盆V20相关（OR=1.191,P=0.042）。结论 宫颈癌术后放疗行BM-sparing IMRT能降低骨盆受量和血液不良反应发生率,骨盆受量与骨盆冠状轴长呈负相关,血液不良反应发生与骨盆V20相关。

Objective To investigate the effects of bone marrow （BM）-sparing pelvic intensity-modulated radiotherapy （IMRT） after surgery for cervical cancer on radiation dose to the target volume,organs at risk （OAR）,and hematologic toxicity. Methods Ten patients with cervical cancer who would receive postoperative radiotherapy were selected. BM-sparing pelvic IMRT and conventional IMRT were performed for the same image by the Varian planning system. The radiation dose to the pelvis,the dose distribution of the target volume,and the radiation dose to OAR were compared between the two plans. A total of 30 patients with cervical cancer who had received postoperative radiotherapy were selected to investigate the relationships of the radiation dose to the pelvis with the lengths of the pelvis in coronal axis,sagittal axis,and vertical axis and the pelvic volume. A total of 41 patients with cervical cancer who would receive postoperative radiotherapy were randomly divided into observation group and control group. The observation group was given BM-sparing IMRT,while the control group was given conventional IMRT.The incidence of grade ≥2 hematologic toxicity was compared between the two groups and the relationship between the hematologic toxicity and the radiation dose to the pelvis was investigated. Resutls Both groups showed excellent dose coverage to the clinical target volume. There was no significant difference in radiation dose to the OAR between the two groups （all P〉0.05）.However,the observation group had significantly lower Dmean,V10,V20,V40,and V50 of the pelvis than the control group （P=0.003-0.045）.The Pearson correlation analysis showed that Dmean,V20,V30,V40,and V50 of the pelvis were negatively correlated with the length of the pelvis in coronal axis （P=0.008-0.038）.The observation group had a significantly lower incidence of hematologic toxicity than the control group （P=0.019）.The logistic regression analysis showed that the development of hematologic toxicity was significantly associated with V20 of the pelvis （OR=1.191,P=0.042）. Conclutions BM-sparing IMRT after surgery for cervical cancer can reduce the radiation dose to the pelvis and the incidence of blood toxicity. The radiation dose to the pelvis is negatively correlated with the length of the pelvis in coronal axis. The development of hematologic toxicity is associated with V20 of the pelvis.