CT低剂量扫描结合ASiR算法在儿童鼻窦检查中的应用研究

Research on application of sinus low-dose CT scanning combined with adaptive statistical iterative reconstruction for children

目的:探讨CT低剂量扫描结合自适应统计迭代重建(adaptive statistical iterative reconstruction,ASiR)算法在儿童鼻窦检查中的应用价值。方法:将150例临床疑诊鼻窦疾患的儿童随机分为常规剂量组、低剂量A组、低剂量B组,每组50例。常规剂量组采用120 kV、90 mA扫描,行滤波反投影法(filtered back projection,FBP)重建图像,低剂量A、B组采用100 kV、50 mA扫描,分别行FBP、ASiR算法(将权重值设定为50%)重建图像。对图像质量进行主观评分,并测量噪声值(以CT值的标准差SD作为噪声值)及对比噪声比(contrast to noise ratio,CNR);记录CT容积剂量指数(CT dose index volume,CTDIvol)、剂量长度乘积(dose-length product,DLP),计算有效辐射剂量(effective dose,ED)。采用SPSS 20.0进行统计学分析。结果:低剂量B组与常规剂量组比较,图像质量主观评分差异无统计学意义(P>0.05),低剂量A组与常规剂量组、低剂量B组比较,图像质量主观评分明显下降,差异有统计学意义(P<0.05);低剂量A、B组较常规剂量组SD值升高、CNR值降低,差异有统计学意义(P<0.05);低剂量A、B组CTDIvol、DLP及ED较常规剂量组明显降低,差异有统计学意义(P<0.05)。结论:在儿童鼻窦CT检查中,低剂量(100 kV、50 mA)扫描结合ASiR算法可在得到满足临床诊断需求图像的同时明显降低辐射剂量。

Objective To explore the application value of low-dose CT scanning combined with adaptive statistical iterative reconstruction(ASiR) for the examination of the children. Methods A total of 150 children with clinically suspected sinus diseases were randomly divided into 3 groups(n=50). The patients in the conventional dose group were scanned under 120 kV and 90 mA and the image reconstruction way was filtered back projection(FBP). The patients in the low-dose group A and group B were scanned under 100 kV and 50 mA and the images were reconstructed via FBP and ASiR algorithm(the weight value was set to 50%), respectively. Subjective scoring was performed on image quality. The standard deviation of CT dose,which was used as the noise value, and the contrast to noise ratio(CNR) were measured. CT dose index volume(CTDIvol) and dose-length product(DLP) were recorded and the effective dose(ED) was calculated. SPSS 20.0 software was used for data analysis. Results There was no significant difference in the subjective scores of image quality between the low-dose group B and conventional dose group(P>0.05). The subjective score of image quality was significantly lower in the low-dose group A than those in the conventional dose group and the low-dose group B, and the difference was statistically significant(P<0.05).Compared with those in the conventional dose group, SD value was increased while CNR value was decreased in the low dose group. However, CTDIvol, DLP and ED were significantly lower in the low-dose group A and group B than those in the conventional dose group, and the differences were statistically significant(P <0.05). Conclusion In sinus CT examination among children, low dose(100 kV, 50 mA) scanning combined with ASiR algorithm can meet the needs of clinical diagnosis and evidently reduce the radiation dose simultaneously.