ASIR结合自动调节管电流技术在降低胸部CT辐射剂量的研究  

The Application of ASIR Combined with Automatic Tube Current Modulation in Chest CT with Reduced Radiation Dose

作　　者：田骞 张喜荣 贾永军 张明 Tian Qian;Zhang Xirong;Jia Yongjun;Zhang Ming(Department of Medicine,Xi'an Jiaotong University,Xi'an Shaanxi 710000;Department of Radiology,Affiliated Hospital of Shaanxi University of Traditional Chinese Medicine,Xianyang,Shaanxi 712000)

机构地区：[1]西安交通大学医学部,陕西西安710000 [2]陕西中医药大学附属医院放射科,陕西咸阳712000

出　　处：《现代医用影像学》2021年第10期1820-1825,共6页Modern Medical Imageology

摘　　要：目的:评价使用低剂量CT扫描医学体模胸部图像时,自适应统计迭代重建技术(ASIR)对扫描图像质量的影响。方法:使用GE Discovery CT750HU,相同管电压(120kVp),对胸部模型进行4种不同噪声指数(NI14、NI16、NI18、NI20)的扫描。使用FBP重建NI=14的扫描,并分别重建不同NI(16、18、20)的20%、40%、60%及80%ASIR图像。在重建图像的上、中、下水平分别测量肺、主动脉和背部肌肉的CT值和标准差(SD)。计算动脉的信噪比(SNR)和对比噪声比(CNR)。获得每组CT剂量指数(CTDI),剂量长度乘积(DLP),计算有效剂量(ED)。两位经验丰富的医生使用5级评分标准对图像主观评分进行盲法评估。结果:NI=18组平均ED较NI=14降低了约39.25%。与FBP重建图像相比,ASIR 60%所得到的图像具有较小的背景图像噪声和较高的CNR。两组图像的质量评分没有显著差异(P> 0.05)。结论:胸部CT扫描时,使用自动管电流调节技术将噪声指数设置为18,并选择ASIR权重为60%对图像进行重建,可以在保持图像质量的同时大幅降低辐射剂量。Objective:To evaluate the ability of using the adaptive statistical iterative reconstruction(ASIR) for improving image quality of chest CT with reduced radiation dose.Method:CT scans were performed using a chest phantom with 4 different noise indices(14 HU,16 HU,18 HU,20 HU) and the same tube voltage(120 kVp) on a GE Discovery CT750 HU. The filtered back-projection(FBP) reconstruction was used for the scan with a noise index of 14 HU for comparison purpose and different percentages of ASIR from 20% to 80% in a 20% increment were used for other scans. The CT values and standard deviation(SD) values of the lung, aorta and back muscle at the same imaging level were measured. The signal to noise ratio(SNR=CTartery/SDmuscle) and contrast to noise ratio(CNR=(CTartery-CTmuscle)/SDmuscle) for the artery were calculated. The CT dose index(CTDI), dose-length produce(DLP) of each scan were obtained, their effective doses(ED) were calculated. The subjective image scores of these groups were assessed blindly by two experienced physicians using a 5-point system.Result:At NI=18, the average ED was decreased by about 39.25% when compared to the standard dose group. The 60%ASIR images had smaller background image noise and higher CNR than that of the FBP images. There was no significant difference between the two image groups(P>0.05).Conclusion:Combining automatic tube current modulation with ASIR at 60% percentage in chest CT, radiation dose can be greatly reduced, while maintaining image quality.

关 键 词：辐射剂量 自适应统计迭代重建 图像质量 体层摄影术 X线计算机 

分 类 号：R816.4[医药卫生—放射医学]