摘要
目的:利用合成CT(sCT)对宫颈癌调强放疗进行剂量学分析,与计划CT(pCT)展开DVH参数比较,探讨剂量分布差异与膀胱充盈度变化相关性。方法:选取宫颈癌患者第1、3、5周锥形束CT,分别与pCT变形配准生成sCT1、sCT2、sCT3用于剂量再计算,以评估调强放疗早、中、后期剂量分布变化,并采用配对样本t检验分析实际照射与pCT计划间剂量差异。基于线性回归分析膀胱充盈度对剂量分布的影响。结果:32例患者共计生成96组sCT纳入分析。放疗早、中及后期剂量分布差异基本一致。在基于sCT计算实际受照剂量中,sCT与pCT间PTV靶区剂量覆盖率D95%未发生显著改变,D50%升高0.99%(P=0.015);sCT中膀胱体积平均减少7.60%(P<0.001),剂量整体升高,V30 Gy升高2.86%(P=0.003);直肠体积与剂量未发生显著改变。膀胱充盈度显著影响剂量分布,其中PTV中位剂量变化(RD50)、膀胱V30变化(RBV30)均与膀胱体积比例(RVB)存在显著线性负相关性,分别有RD50=-0.071×RVB+107.96;RBV30=-0.414×RVB+144.60。根据RVB线性回归方程可预估剂量分布变化。结论:sCT丰富了放疗计划质控手段,能有效监测宫颈癌调强计划的实施。基于剂量分布变化的预估有助于放疗计划的及时优化。
Objective To conduct dosimetric analysis on intensity-modulated radiotherapy for cervical cancer using synthetic computed tomography(sCT),compare dose-volume histogram parameters with those derived from planning computed tomography(pCT),and explore the correlation between dose distribution differences and changes in bladder filling status.Methods The conebeam computed tomography images were acquired from cervical cancer patients at weeks 1,3,and 5,and then deformably registered to the corresponding pCT scans to generate sCT1,sCT2,and sCT3 for dose recalculation,thereby evaluating dose distribution changes during early,middle,and late phases of intensity-modulated radiotherapy.Paired sample t-test was conducted to analyze dose differences between actual irradiation and pCT-based plan.Linear regression analysis was used to evaluate the effects of bladder filling status on dose distribution.ResultsAtotal of 96 sets of sCT were generated from 32 patients and included in the analysis.The dose distribution differences were consistent across the early,middle,and late phases of radiotherapy.For the actual irradiated doses calculated based on sCT,no significant changes were observed in the dose coverage rate(D95%)of planning target area between sCT and pCT,while D50%increased by 0.99%(P=0.015).In the sCT-based analysis,the average bladder volume decreased by 7.60%(P<0.001);the overall dose increased;and V30 Gy increased by 2.86%(P=0.003).No significant change was found in either rectal volume or dose.Bladder filling status significantly affects dose distribution.Both the change of PTV median dose(RD50)and the change of bladder V30(RBV30)were significantly negatively correlated with the ratio of bladder volume(RVB):RD50=-0.071×RVB+107.96;RBV30=-0.414×RVB+144.60.Dose distribution changes could be predicted using linear regression equation for RVB.Conclusion sCT enriches the quality control modalities for radiotherapy plans and enables effective monitoring of the implementation of intensity-modulation radiotherapy plan for cervical cancer.Prediction of dose distribution changes facilitates the timely radiotherapy plan optimization.
作者
潘淑豪
吴黎明
PAN Shuhao;WU Liming(Department of Radiation Oncology,the First Affiliated Hospital of Anhui Medical University,Hefei 230022,China)
出处
《中国医学物理学杂志》
2025年第12期1569-1575,共7页
Chinese Journal of Medical Physics
基金
安徽高校协同创新项目(GXXT-2022-011)。
关键词
宫颈癌
调强放疗
合成CT
剂量分布
膀胱充盈度
cervical cancer
intensity-modulated radiotherapy
synthetic computed tomography
dose distribution
bladder filling status
