胸部CT检查中两种低辐射剂量技术应用研究

Application of CARE kV and SAFIRE in Contrast-Enhanced Chest CT Examination

目的验证基于检查类型和受检者体型的CT管电压自动调节技术(CARE kV)和基于原始数据的正弦图确认迭代重建技术(SAFIRE)对提高胸部CT检查图像质量,同时降低辐射剂量的效果。方法胸部占位性病变患者60例,年龄30～80岁,平均(56.9±11.8)岁,体重质量指数(BMI)(23.4±3.3)kg/㎡。分两组,每组30例,使用Siemens Somatom Flash CT机行胸部CT增强扫描。组1:采用常规120 kV扫描条件,数据经过滤波反投影技术(FBP)重建获取图像;组2:采用CARE kV功能启用的扫描条件,数据经过FBP(组2a)及SAFIRE(组2b)两种重建方式进行重建并获取图像;由两位放射科医师独立、双盲对图像用5分法进行主观评估(等级由5分到1分,分别代表图像质量极好到图像质量无法满足诊断要求)。图像的密度及噪声由另外一名医师进行测量,并由此计算出图像的信噪比、对比噪声比。记录每例患者基础信息:如性别,年龄等;经过扫描获得的剂量信息:如kV、有效剂量等。使用SPSS Statistics 17.0统计软件对数据进行处理分析。结果所有病例图像均满足诊断要求(3组图像平均得分分别为3.83、3.60、4.33,K=0.749,P=0.003)。组2平均容积CT剂量指数低于组1约17.1%(t=3.111,P=0.003);有效放射剂量(2.26±0.77)mSv较组1[(2.82±1.15)mSv]降低约19.7%(t=3.370,P=0.001)。组2a(13.3±3.3)、2b(18.4±4.7)对比噪声比平均高于组1(11.4±3.9)分别约16.7%(t=2.065,P=0.043)、61.2%(t=6.312,P<0.001)。结论联合使用CARE kV和SAFIRE可以降低受检者辐射剂量,同时提高CT图像质量。

Objective To evaluate the feasibility of automated tube potential selection algorithm （CARE kV） and Sinogram Affirmed Iterative Reconstruction （SAFIRE） on chest CT image quality improvement and radiation dose reduction. Methods Sixty consecutive patients with neoplasms were enrolled and divided into 2 groups equally. Patients of group 1 underwent 128 slice DSCT routine scan, and the images were reconstructed with FBP. The patients of group 2 underwent 128 slice DSCT CARE kV scan, and the images were reconstructed with FBP（ group 2a） and SAFIRE（ group 2b） separately. The image quality was evaluated by two observers using 5-point score （5 ： excellent to 1 ： non-diagnostic） independently. Image attenuation and noise were measured, contrast-to-noise-ratio （CNR） was calculated, the basic information of patients,such as age and gender, as well as radiation dose were recorded. Results The average image quality score of groups 1,2a and 2b was 3.83,3.60,g. 33 respectively. The image quality of group 2b and 2a was better than that of group 1 （ K = 0. 749, P = 0. 003 ）. The CNR of group 2a and 2b was increased to 16.7 % （ t = 2. 065, P = 0. 043 ）, 61.2% （ t =6. 312, P 〈 0.001 ）compared with that of group 1. The effective radiation dose of group 2 （2.26 ± 0.77 ） mSv was signifi- cantly lower than that of group 1 （2.82 ± 1.15 ）, corresponding to an overall dose reduction of 19.7% （ t = 3. 370, P =0.001 ）. Conclusion Combined application of both CARE kV and SAFIRE can improve image quality and reduce the radiation dose of patients.