智能最佳管电压联合自动管电流在降低胸部CT扫描剂量中的应用

Application of the Technique of CARE kV Combined with CARE dose 4D in Reducing Radiation Dosage Ofchest CT Scanning

目的探讨螺旋CT智能最佳管电压(CARE kV)联合自动管电流(CARE Dose 4D)技术在胸部CT扫描中降低辐射剂量的应用。方法将行胸部CT检查的120例患者分为两组,对照组(n=60)采用CARE Dose 4D扫描技术,试验组(n=60)采用CARE Dose 4D联合CARE kV扫描技术,其余扫描参数和图像重组参数均相同。分析每组患者的肺尖部、主动脉弓下缘水平、左房中部水平及肺底部4幅图像,对比两组的图像质量。测量肺重组及纵隔重组图像的噪声、对比噪声比(CNR)、信噪比(SNR)。记录每组患者的CT容积剂量指数(CTDIvol)、剂量长度乘积(DLP)、有效辐射剂量(ED)。结果试验组ED为(2.82±0.42)mSv,较对照组的(3.19±0.48)mSv明显降低,差异具有统计学意义(P<0.05)。对照组图像平均优良率为93.3%,试验组为91.7%,两组图像优良率相近,差异无统计学意义(P>0.05);然而肺尖水平试验组优良率明显高于对照组,而左房中部水平却低于对照组,主动脉弓下缘及肺底水平两组相近。两组平均CNR、SNR差异均无统计学意义(P>0.05)。结论 CARE kV联合CARE Dose 4D技术,能在有效减低患者辐射剂量的同时,保证图像质量,适合临床推广应用。

Objective To investigate the combination technique of CARE kV with CARE dose 4 D in reducing radiation dosage of chest CT scanning. Methods 120 patients were randomly divided into two groups who will take chest CT examination,control group(n=60) with CARE Dosed 4 D scanning and research group(n=60) with by CARE dosed 4 D and CARE kV scanning,the rest of the scanning parameters and image reconstruction were set in the same way.Four levels of each CT image from 120 patients were selected,including apex of lung level,central left aorta level,edge of the aortic arch and lung base levels,to compare the image quality. Moreover,contrast to noise ratio(CNR) and signal-to-noise ratio(SNR) were also measuredin lung and mediastinum reconstruction image.Volume CT dose index(CTDI vol) and dosed length product(DLP) of each patient were recorded and effective dosed(ED) was then calculated to evaluate radiation dosage of each group. Results The average ED of the research group was(2.82±0.42) mSv,which was lower than control group(3.19±0.48)mSv with significant difference between two group(P<0.05). Though there was no statistical difference in excellent rate between two group(93.3%vs 91.7%,P>0.05),CT image of research group of lung apex level showed higher excellent rate than that in control group(P<0.05),but CT image in central left aorta level presented lower excellent rate than that of control group(P<0.05),excellent rates of CT images in edge of the aortic arch and base lung levels were similar in the two groups(P>0.05). In addition,the average of CNR,SNR,CTDI vol,DLP and lesion detection rate of the two groups displayed no significant statistical differences(P>0.05). Conclusion The use of technology of CARE kV combined with CARE dose 4 D can not only effectively reduce the radiation dose of patients,but keep the image quality,which is suitable for clinical application.