施源器顶端重建偏差对宫颈癌三维腔内后装治疗的剂量学影响  

Dosimetric effects of applicator tip reconstruction uncertainties on three-dimensional intracavitary brachytherapy for vaginal cancer

作　　者：李磊 杨波 LI Lei;YANG Bo(Department of Oncology,the Affiliated Hospital of Southwest Medical University,Luzhou 646000,Sichuan Prov-ince,China)

机构地区：[1]西南医科大学附属医院肿瘤科,四川泸州646000

出　　处：《西南医科大学学报》2021年第2期138-143,共6页Journal of Southwest Medical University

摘　　要：目的:研究基于CT图像的不锈钢Fletcher施源器顶端重建偏差对宫颈癌三维腔内后装治疗的剂量学影响。方法:选取已完成治疗的根治性宫颈癌患者20例,直接修改患者原后装治疗计划的offset值以模拟施源器顶端重建偏差为±1 mm、±2 mm和±3 mm时的剂量分布。统计HR-CTV和IR-CTV的D_(100)、D_(90)、D_(50)、V_(200)、V_(150)、V_(100)和V_(90),膀胱、直肠、乙状结肠和小肠的D_(0.1cc)、D_(1cc)、D_(2cc)和D_(5cc),以及适形指数,分析施源器顶端重建偏差对宫颈癌三维腔内后装治疗的剂量学影响。结果:对CTV评价参数,HR-CTV和IR-CTV的相关DVH参数的偏差随施源器顶端重建偏差的增大而增大(P <0.05);相同施源器顶端重建偏差条件下,HR-CTV的相关DVH参数偏差随体积或剂量的增大而增大(P <0.05),IR-CTV的剂量参数偏差随体积的增大而增大(P <0.05),而体积参数偏差随剂量的增大而减小(P <0.05)。对OARs评价参数,OARs的剂量偏差随施源器顶端重建偏差的增大而增大(P <0.05);相同施源器顶端重建偏差条件下,不同危及器官的剂量偏差变化有所不同:膀胱的剂量偏差随体积的增大而增大(P <0.05);直肠和乙状结肠的剂量偏差随体积的增大而减小(P <0.05);小肠的剂量偏差和体积间无统计学意义(P> 0.05)。对HR-CTV D_(90)、IR-CTV D_(90)、膀胱D_(2cc)、直肠D_(2cc)、乙状结肠D_(2cc)、小肠D_(2cc),施源器顶端重建偏差为2 mm时,剂量偏差分别为3.58%、2.84%、3.4%、3.47%、3.99%和2.10%。结论:推荐施源器顶端重建偏差控制在±1 mm。日常临床工作中,CT扫描层厚最好不要超过3 mm。Objective:To investigate the dosimetric effects of computed tomography(CT)images-based recon⁃struction uncertainties of the tip of the stainless-steel Fletcher applicator on three-dimensional intracavitary brachy⁃therapy for cervical cancer.Methods:We selected 20 patients with cervical cancer who completed treatment,and di⁃rectly modified the offset values of their original brachytherapy plans to simulate the dose distribution at±1 mm,±2 mm,and±3 mm reconstruction uncertainties of the applicator tip.We obtained the D100,D90,D50,V200,V150,V100,and V90 values for high-risk clinical target volume(HR-CTV)and intermediate-risk CTV(IR-CTV),the D0.1cc,D1cc,D2cc,and D5cc values for the bladder,rectum,sigmoid colon,and small intestine,and the conformity index values to an⁃alyze the dosimetric effects of applicator tip reconstruction uncertainties on three-dimensional intracavitary brachy⁃therapy for cervical cancer.Results:The deviation of dose-volume histogram(DVH)parameters for HR-CTV and IR-CTV increased with the increase in applicator tip reconstruction uncertainty(P<0.05).For a fixed applicator tip reconstruction uncertainty,the deviation of DVH parameters for HR-CTV increased with the increase in volume or dose(P<0.05);the deviation of dose parameters for IR-CTV increased with the increase in volume(P<0.05),while the deviation of volume parameters decreased with the increase in dose(P<0.05).The dose deviation for or⁃gans at risk(OARs)increased with the increase in applicator tip reconstruction uncertainty(P<0.05).For a fixed ap⁃plicator tip reconstruction uncertainty,there were differences in dose deviation changes between different OARs.For the bladder,the dose deviation increased with the increase in volume(P<0.05).For the rectum and sigmoid colon,the dose deviation decreased with the increase in volume(P<0.05).For the small intestine,there was no significant association between the dose deviation and volume(P>0.05).When the applicator tip reconstruction uncertainty was 2 mm,the dose deviation was

关 键 词：施源器重建 剂量学 近距离治疗 宫颈癌 

分 类 号：R815[医药卫生—放射医学]