【摘要】 目的:研究宫颈癌容积旋转调强放疗过程中,利用图像引导技术评估膀胱与直肠因平移摆位误差因素对受照剂量的影响。方法:入组2017年2～4月的25例行容积旋转调强放疗的宫颈癌病人。在计划CT图像和首次摆位的锥形束CT(CBCT)图像中勾画出膀胱和直肠。然后根据首次摆位误差,对膀胱和直肠在前后、左右、头脚方向上进行相应的平移。分别比较计划设计与加入平移摆位误差下的膀胱和直肠剂量差异,并用配对t检验分析差异。结果:在计划CT与CBCT图像上勾画出的直肠体积为(33.0±16.0)和(21.8±16.5)cm3,膀胱体积为(387.1±222.3)和(227.8±107.3)cm3。在计划CT图像与考虑平移摆位误差的CBCT图像上,直肠的V50为(17.27±13.42)%和(23.9±26.58)%,膀胱的V50为(33.59±12.2)%和(44.27±22.61)%,直肠的最大剂量为(5 324±383)和(5 370±441)c Gy,膀胱的最大剂量为(5 547±365)和(5 513±328)c Gy。直肠和膀胱的V50均有统计学意义(t=-3.60, P<0.01;t=-2.98, P<0.01),直肠和膀胱的最大剂量均无统计学意义(t=-1.18, P=0.20;t=0.66, P=0.51)。结论:宫颈癌放射治疗中,膀胱和直肠在计划CT和首次治疗时的体积与剂量均有较大差异,故应该多次采集图像来评估剂量分布,才能准确评价放射治疗的真正疗效。更多还原

【Abstract】 Objective To evaluate the effects of translational setup errors on the doses to bladder and rectum during imageguided volumetric modulated arc therapy for cervical cancer. Methods Twenty-five patients receiving volumetric modulated arc therapy for cervical cancer from February 2017 to April 2017 were enrolled in this study. Bladder and rectum were delineated on the planning computed tomography(CT) images and the cone beam CT(CBCT) images obtained in the first treatment fraction. Then, bladder and rectum were shifted in the anterior-posterior, left-right, and superior-inferior directions according to the first setup errors. The planned dose of bladder and rectum were compared by those data obtained with CBCT images considering setup errors, and the dosimetric differences were compared with paired t-test. Results The rectum volumes delineated on the planning CT and CBCT images were(33.0±16.0) cm3 and(21.8±16.5) cm3, respectively,and the bladder volumes were(387.1±222.3) and(227.8±107.3) cm3, respectively. The V50 of rectum based on the planning CT and CBCT images was(17.27±13.42) % and(23.9±26.58) %, respectively; and the V50 of bladder was(33.59±12.2) %and(44.27±22.61) %, respectively, with statistical differences(t=-3.60, P<0.01; t=-2.98,P<0.01). The maximum dose of rectum based on the planning CT and CBCT images was(5 324±383) and(5 370±441) cGy, respectively; and the maximum dose of bladder was(5 547±365) and(5 513±328) cGy, respectively, with no statistical differences(t=-1.18, P=0.20; t=0.66,P=0.51). Conclusion During the radiotherapy course for cervical cancer, the volumes and doses of bladder and rectum in planning CT are significantly different from those in the first treatment fraction. CT images should be obtained for multiple fractions to evaluate the dose distribution and further assess the benefits of radiotherapy.更多还原