idose^4重建技术在儿童气管及支气管CT低剂量扫描的应用

Application of idose^4 reconstruction technique in low-dose CT scan of children’s trachea and bronchi

目的研究迭代重建技术idose 4在儿童气管及支气管CT低剂量扫描的应用及对图像质量的影响。方法60例年龄为5个月至5周岁气管及支气管CT检查患儿纳入研究,按扫描方式不同随机分成两组,每组30例。常规剂量组(A组):管电压80kV,管电流为55mAs,采用idose 43级重建技术。低剂量组(B组):管电压80kV;管电流为30mAs,分别采用idose 42~6级五种重建技术。两组均采用自动管电流调制技术。比较A、B两组患儿辐射剂量评价参数,即:CT容积剂量指数(CTDIvol)、剂量长度乘积(DLP)、有效辐射剂量(ED)及体型特异性剂量评估(SSDE)之间的差异,并研究各参数值与患儿身高及体重的相关性。比较A、B两组图像噪声、信噪比(SNR)、主观图像质量。结果B组CTDIvol、DLP、ED及SSDE值(0.54±0.08,16.78±4.16,0.41±0.05,1.18±0.16)均较A组(1.09±0.13,31.91±6.16,0.70±0.11,2.37±0.19)显著降低约50%(t=14.53,8.63,10.11,20.22,P<0.05)。SSDE值与患儿身高(r=0.49,P<0.5)及体重(r=0.64,P<0.05)有强相关性。B组所有图像噪声较A组高,差异有统计学意义(P<0.05);B组图像SNR降低,在idose^4 2,3,4级时与A组差异显著(P<0.05),在idose^4 5,6级时,与A组SNR无明显差异(P>0.05);主观图像质量评价B组idose^4 2,3,4,6级低于A组,差异显著(P<0.05),idose^4 5级与A组间差异不具统计学意义(P>0.05)。结论儿童胸部CT检查,管电压80kV,管电流30mAs(自动管电流调制技术),结合idose^4 5级重建技术,图像质量满足临床诊断要求,同时辐射剂量比常规扫描降低约50%;SSDE评价辐射剂量与受检者体型因素关系较大。

Objective To evaluate the application of iterative reconstruction technique idose 4 in low-dose CT scanning of children'strachea and bronchusin and its effect on imagequality.Methods 60 pediatric patients who were 5 months to 5 years old undergoing strachea and bronchusin CT scan were randomly divided into traditional dose group(Group A)and low-radiation group(Group B)and each group contained 30 cases.Group A:the tube voltage is 80 kV,the tube current is 55 mAs,idose 43 reconstruction mode;Group B:the tube voltage is 80 kV,the tube current is 30 mAs,idose 42~6 reconstruction mode.Both groups adopted the ATCM technique(Dose Right:Z-DOM),and the other scanning parameters were same.The radiation dose parameters of volumetric CT dose index(CTDIvol),dose length product(DLP),effective radiation dose(ED),and size-specific dose assessment(SSDE)were compared between the two groups.The correlations between each parameter and the height and weight of the pediatric patients were analyzed.The image noise,signal-to-noise ratio(SNR),and subjective image quality between the two groups were compared.Results The values of CTDIvol,DLP,ED,and SSDE in group B(0.54±0.08,16.78±4.16,0.41±0.05,1.18±0.16)were 50%less than those in group A(1.09±0.13,31.91±6.16,0.70±0.11,2.37±0.19)(t=14.53,8.63,10.11,20.22,P<0.05).The value of SSDE was strongly correlated with height(r=0.49,P<0.05)and body weight(r=0.64,P<0.05)in children.The noise of all images in group B was significantly higher than that in group A(P<0.05).The SNR of idose 42,3,4 images in group B was lower than that in group A,and the difference was statistically significant(P<0.05).The SNR of idose^4 5,6 in group B was not statistically different from group A(P>0.05).The subjective image quality scores of idose^4 2,3,4 and 6 in group B were lower than those in group A,and the difference was statistically significant(P<0.05);The subjective images quality scores of the idose^4 5 in group B and group A were not statistically significant(P>0.05).Conclusion 80 kV,30 mAs tube current automatic modulation mode combined with idose^4 5 reconstruction mode reduced radiation dose by approximately 50%compared to the traditional group,and its image quality is perfect for clinical diagnosis in pediatric patients undergoing trachea and bronchus CT scanning.SSDE is closely associated with the body factor of pediatric patients.