三维超声在前列腺癌图像引导放疗中的应用与评价研究

Application and evaluation study of 3D ultrasound in image guided radiotherapy for prostate cancer

目的以锥形束CT校准为金标准,评价前列腺癌图像引导放疗中三维超声校准的准确度,并分析影响其准确度的危险因素。方法选择2018年12月至2021年12月河北北方学院附属第一医院放疗科51例前列腺癌患者为研究对象。患者均接受每周3次分次容积旋转调强放疗前基于骨骼的锥形束CT校准和基于软组织的三维超声校准。以锥形束CT校准数据为金标准,采用Bland-Altman法分析三维超声校准数据与其一致性。准确度允许阈值设置为3 mm,评价三维超声相对锥形束CT校准的准确度。采用logistic回归分析影响三维超声校准准确度的危险因素。结果共获取51例患者左右、头脚、腹背3个方向上765对锥形束CT和三维超声校准数据。左右方向上三维超声校准数据和锥形束CT校准数据分别为(1.39±0.11)和(1.13±0.07)mm,头脚方向上分别为(1.98±0.20)和(1.61±0.12)mm,腹背方向上分别为(2.68±0.48)和(1.78±0.27)mm,差异均具有统计学意义(t=-6.42,P<0.001;t=-7.07,P<0.001;t=-7.34,P<0.001)。Bland-Altman法分析结果显示,两种方法校准数据在3个方向上一致性可以接受。3个方向上三维超声相对锥形束CT校准数据差异<3 mm的数据分别为左右676对(88.37%)、头脚604对(78.95%)、腹背577对(75.42%)。左右方向上差异具有统计学意义的因素包括年龄(χ^(2)=18.27,P<0.001)、前列腺体积(χ^(2)=14.55,P<0.001)、查尔森合并症指数(CCI)(χ^(2)=8.01,P=0.005)和射野范围(χ^(2)=11.30,P<0.001),其中年龄(OR=2.02,95%CI为1.90~3.39,P=0.010)和射野范围(OR=1.45,95%CI为1.18~2.55,P=0.020)均为影响左右方向三维超声校准准确度的独立危险因素。头脚方向上差异具有统计学意义的因素包括年龄(χ^(2)=80.68,P<0.001)、体质量指数(χ^(2)=35.89,P<0.001)和射野范围(χ^(2)=40.39,P<0.001),其中年龄(OR=1.49,95%CI为1.15~2.09,P=0.021)和射野范围(OR=1.10,95%CI为1.01~1.90,P=0.034)均为影响头脚方向三维超声校准准确度的独立危险因素。腹背方向上差异具有统计学意义的因素包括年龄(χ^(2)=46.07,P<0.001)、CCI(χ^(2)=47.97,P<0.001)和射野范围(χ^(2)=11.86,P=0.001),其中年龄(OR=1.91,95%CI为1.22~3.45,P=0.015)和射野范围(OR=2.89,95%CI为1.45~3.90,P=0.001)均为影响腹背方向三维超声校准准确度的独立危险因素。结论三维超声相对锥形束CT校准结果的一致性和准确度均可以接受。进行三维超声校准前需考虑患者年龄和射野范围,从而降低对准确度的影响。

Objective To evaluate the accuracy of 3D ultrasound calibration in image guided radiotherapy for prostate cancer by taking cone beam CT calibration as the gold standard,and to analyze the risk factors of accuracy.Methods From December 2018 to December 2021,51 patients with prostate cancer from the Department of Radiation Oncology,First Affiliated Hospital of Hebei North University were selected as the study subjects.They received cone beam CT calibration based on bone and 3D ultrasound calibration based on soft tissue before fraction volumetric modulated arc therapy treatment three times a week.Taking cone beam CT calibration data as the gold standard,the Bland-Altman method was used to analyze the consistency of 3D ultrasound calibration data with the former.Taking 3 mm as the allowable threshold of accuracy,the calibration accuracy of 3D ultrasound relative to cone beam CT was evaluated.Logistic regression was used to analyze the risk factors affecting the accuracy of 3D ultrasound calibration.Results A total of 765 pairs of cone beam CT and 3D ultrasound calibration data were obtained from 51 patients in left-right,superior-inferior and anterior-posterior directions.The calibration data of 3D ultrasound and cone beam CT were(1.39±0.11)and(1.13±0.07)mm in the left-right direction,(1.98±0.20)and(1.61±0.12)mm in the superior-inferior direction,(2.68±0.48)and(1.78±0.27)mm in the anterior-posterior direction,respectively,with statistically significant differences(t=-6.42,P<0.001;t=-7.07,P<0.001;t=-7.34,P<0.001).The analysis results of Bland-Altman showed that the consistency of calibration data of the two methods were acceptable in three directions.The number of pairs of 3D ultrasound relative to cone beam CT calibration data difference<3 mm in the three directions were 676(88.37%)on the left-right direction,604(78.95%)on the superior-inferior direction,and 577(75.42%)on the anterior-posterior direction.The factors with statistically significant differences in the left-right direction included age(χ^(2)=18.27,P<0.001),prostate volume(χ^(2)=14.55,P<0.001),Charlson comorbidity index(CCI)(χ^(2)=8.01,P=0.005)and field range(χ^(2)=11.30,P<0.001).Age(OR=2.02,95%CI:1.90-3.39,P=0.010)and the field range(OR=1.45,95%CI:1.18-2.55,P=0.020)were the independent risk factors affecting the accuracy of 3D ultrasound calibration in the left-right direction.The factors with statistically significant differences in the superior-inferior direction included age(χ^(2)=80.68,P<0.001),body mass index(χ^(2)=35.89,P<0.001)and field range(χ^(2)=40.39,P<0.001).Age(OR=1.49,95%CI:1.15-2.09,P=0.021)and the field range(OR=1.10,95%CI:1.01-1.90,P=0.034)were the independent risk factors affecting the accuracy of 3D ultrasound calibration in the superior-inferior direction.The factors with statistically significant differences in the anterior-posterior direction included age(χ^(2)=46.07,P<0.001),CCI(χ^(2)=47.97,P<0.001)and field range(χ^(2)=11.86,P=0.001).Age(OR=1.91,95%CI:1.22-3.45,P=0.015)and the field range(OR=2.89,95%CI:1.45-3.90,P=0.001)were the independent risk factors affecting the accuracy of 3D ultrasound calibration in the anterior-posterior direction.Conclusion The consistency and accuracy of the calibration results of 3D ultrasound relative to cone beam CT are acceptable.It is necessary to consider the patient's age and field range to reduce the impact on accuracy before conducting 3D ultrasound calibration.