摘要目的 宫颈癌术后IMRT中通过分析两种骨盆的定义方法以及骨盆受量的影响因素来评估和预测骨盆的剂量,为宫颈癌术后IMRT中骨盆的保护提供参考.方法 选择60例骨盆未限量的宫颈癌术后IMRT患者,按照解剖方法和Mell方法勾画两种骨盆轮廓(骨盆解剖、骨盆Mell),基于骨盆解剖限量重新设计治疗计划后分析两者的剂量关系.应用Pearson法分析相关性,Logistic多元回归分析影响骨盆解剖剂量的因素并建立剂量预测模型.结果 骨盆解剖、骨盆Mell体积分别为925.82、1 141.20cm3(p=0.000).骨盆解剖与骨盆Mell剂量存在相关性(r＞0.622,P=0.000),前者剂量明显大于后者;两者V1o、V20、V30的关系分别为y=-8+ 1.01x、y=-13+ 1.05x、y=-4+0.9x.文献推荐骨盆Mell限量标准(V1o≤90％、V20≤75％、V30≤60％)经计算得到相应骨盆解剖限量标准为V1o≤97％、V20≤83％、V30≤70％.骨盆解剖限量后可降低受量,其中V1o、V20、V30、Dmean分别降低3.64％、12.69％、12.02％、6.93％(P=0.000、0.000、0.000).多因素分析显示骨盆解剖重叠在PTV内的相对体积是骨盆解剖剂量的影响因素(P＜0.05),当重叠体积＜18％时骨盆限量易达到剂量限值要求.结论 宫颈癌术后IMRT中两种骨盆定义方法均能应用于临床,骨盆限量能显著降低其剂量.骨盆重叠在PTV内的相对体积是骨盆剂量的独立影响因素,重叠体积小于18％的患者其骨盆限量后易达到剂量限值要求.

abstractsObjective To evaluate and predict the pelvic dose by analyzing two pelvic contour definitions and identify the influencing factors of the pelvic dose in postoperative IMRT for cervical cancer,aiming to provide reference for postoperative pelvis-sparing IMRT for cervical cancer.Methods Sixty cervical cancer patients receiving postoperative IMRT with unrestricted pelvic dose were selected.Two sets of pelvic contours (pelvic anatomy and pelvic Mell) were delineated as per the anatomical and Mell methods.The dose relationship between two methods was analyzed after redesigning the treatment plan by limiting dose of pelvic anatomy.The correlation analysis was performed by Pearson's correlation method.The factors affecting the pelvic anatomy dose were identified by Logistic multivariate regression analysis and a dose prediction model was subsequently established.Results The volumes of pelvic anatomy and pelvic Mell were 925.82 cm3 and 1 141.20 cm3(P=0.000).There was a significant correlation between them (r＞0.622,P=0.000).The dose of pelvic anatomy was significantly higher than that of pelvic Mell.The relationship of V10,V20 and V30 between them was y =-8 + 1.01x,y =-13 + 1.05x and y =-4 + 0.9x,respectively.The dose limits of pelvic Mell recommended by literatures (V10＜90％,V20＜75％,V30＜60％)were translated into V10 ＜ 97％,V20 ＜ 83％ and V30 ＜ 70％,respectively.The pelvic anatomy dose was significantly reduced after dose limiting.The V10,V20,V30 and Dmean were significantly decreased by 3.64％,12.69％,12.02％ and 6.93％(P=0.000,0.000,0.000),respectively.Multivariate analysis showed that the overlapping volume of pelvic anatomy within PTV was an independent influencing factor of pelvic anatomy dose (P＜0.05).Patients with a relative overlapping volume of less than 18％ could easily meet the dose limiting requirement.Conclusions Both two pelvic contour definitions can be applied in postoperative pelvis-sparing IMRT for cervical cancer.Use of pelvic dose limiting can significantly reduce the IMRT dose.The overlapping volume of the pelvis within PTV is an independent influencing factor of pelvic dose.Patients whose overlapping volume within the PTV relative to pelvis is less than 18％ can easily meet the dose limiting requirement.