双源CT低剂量扫描在上腹部增强检查中的应用

目的探讨双源CT上腹部增强扫描中低剂量技术的应用。方法搜集2011年7月至2012年2月期间来我院行双源CT上腹部增强检查的连续600例患者,按就诊时间先后分别依次采用常规管电流量(210 mAs)和低管电流量(200、190、180、170及165 mAs)扫描,分别为常规管电流量组和低管电流量组。测量、计算并评估各组患者动脉期和门脉期图像的皮下脂肪标准差(SD)值、肝脏和胰腺信噪比(SNR)、肝脏-竖脊肌和胰腺-竖脊肌对比噪声比(CNR)、图像主观质量评分以及射线剂量指标CT剂量指数(CTDI)、剂量长度乘积(DLP)、有效剂量(ED)。结果各组患者动脉期和门脉期图像的皮下脂肪SD值、肝脏和胰腺SNR、图像主观质量评分和射线剂量指标CTDI、DLP、ED之间差异均有统计学意义(P<0.05);各组肝脏-竖脊肌和胰腺-竖脊肌CNR之间差异无统计学意义(P>0.05)。其中165 mAs管电流量组图像SNR、射线剂量和主观质量评分均为最低,不能满足诊断需求。结论上腹部增强CT检查,通过阶段性降低管电流量使诊断医生逐渐适应低剂量图像质量,从而普及现有设备的低剂量扫描的方法是可行的。双源CT采用170 mAs的参考管电流量,既能获得满足临床诊断的合格图像,又能大大降低患者群体接受的辐射剂量。

Application of Dual-Source Computed Tomography Low Dose Technology in Upper Abdomen Enhanced Inspection

Objective To discuss the application of dual-source computed tomography(CT)low dose technology in the upper abdomen enhanced inspection.Methods Six hundred consecutive patients from July 2011 to February 2012 in this hospital were orderly divided into ordinal tube current(210 mAs)group and low dose tube current group(200 mAs,190 mAs,180 mAs,170 mAs,and 165 mAs).The standard deviation(SD)of subcutaneous fat,signal to noise ratio(SNR)of liver and pancreas,contrast to noise ratio(CNR)of liver-erector spinae and pancreas-erector spinae,score of subjective diagnosis and the indexes of radiation dose,including CT dose index(CTDI),dose length product(DLP),effective dose(ED)were measured,calculated,and assessed respectively on CT images of arterial phase and portal phase from each group.Results The SD of subcutaneous fat,SNRs of liver and pancreas,score of subjective diagnosis,and the CTDI,DLP,ED of CT images in arterial phase and portal phase were significantly different from each other(P<0.05),while CNRs of liver-erector spinae and pancreas-erector spinae were not statistically significant(P>0.05).The SNR,radiation dose,and score of subjective diagnosis of the 165 mAs tube current group were the lowest among all the groups,but the images of the 165 mAs tube current group could not fulfill the need of diagnosis.Conclusions It is really feasible that the method of decreasing tube current gradually in the upper abdomen enhanced CT inspection could ensure that the radiologists could adapt the low dose image bit by bit,and this methods could be popularized to all kinds of CT facilities we own currently.The images with 170 mAs as tube current in the upper abdomen enhanced inspection of dual-source CT could fulfill the need of diagnosis,and the radiation dose of patients is apparently lower than that the conventional scan.