降低管电流对CT结肠仿真内镜图像质量及辐射剂量的影响

目的：探讨降低管电流宝石能谱CT低剂量扫描对结肠仿真内镜成像图像质量及辐射剂量的影响.方法：对45例临床怀疑为结肠息肉病变的患者平均分为3组,行宝石能谱CT降低管电流结肠仿真内镜成像,其中按固定管电流分别为50,30,15 mAs进行扫描,其他参数按常规进行,并对3组图像质量主观评分及有效辐射剂量进行评价.结果：固定管电流为50 mAs（A组）时,结肠仿真内镜成像（CTVC）及透明重组图像（Raysum）平均评分为（2.93±0.26）分,平均容积CT剂量指数（CTDIvol）与剂量长度乘积（DLP）分别为（1.68±0.00） mGy和（80.62±3.44） mGy cm;30 mAs（B组）时,上述平均评分为（2.53±0.52）分,剂量平均分别为（1.01±0.01） mGy和（45.09±5.54） mGy cm;15 mAs（C组）时,上述平均评分为（1.93±0.70）分,剂量平均分别为（0.05±0.00） mGy和（22.16±1.96） mGy cm.3组CTDIvol与DLP平均分别降低了80.05％、88.00％、94.06％和80.73％、88.95％、94.57％.结论：降低管电流在CTVC成像中,在管电流与辐射剂量分别降低88％以上的情况下,仍能兼顾图像质量,而降低至94.57％时,对图像质量影响较大.

THE IMPACT OF LOWER TUBE CURRENT COLONIC GEM ENERGY SPECTRUM CT SCANNING ON IMAGE QUALITY AND RADIATION DOSAGE

Objective：To explore the role of lower tube current gem energy spectrum low dose CT scanning for colon virtual endoscopy imaging scan image quality and dose effect.Methods：Colon virtual endoscopy imaging in 45 patients with suspected lesions of colon polyps was performed with lower tube current gem energy spectrum CT scanning,and the patients were evenly divided into 3 groups according to the fixed tube current of 50,30 and 15 mAs.Other parameters were performed according to routine.The subjective grading and effective radiation dose of the image quality were evaluated.Results：When the tube current was fixed as 50 mAs （group A）,CTVC and the raysum image average scoring was 2.93±0.26 points,average CTDIvol and DLP was 1.68 mGy and 80.62 mGy cm; respectively.When the tube current was fixed as 30 mA （group B）,above average scoring was 2.53±0.52 points,dose average was 1.01 mGy and 45.09 mGy cm; respectively.When the tube current was fixed as 15 mA （group C）,above average scoring was 1.93±0.70 points,dose average was 0.5 mGy and 22.16 mGy cm; respectively.The average of CTDIvol andDLPin three groups decreased 80.05%,88% and 94.06%; and 80.73%,88.95% and 94.57%; respectively.Conclusion：The lower tube current CTVC imaging,in the case of radiation dose to reduce more than 88%,is still able to combine image quality,but reduced to 94%,the picture quality influence is big.