剂量指数在婴幼儿腹部低剂量CT扫描中的应用

Application of Dose Right Index in Infant Abdominal Low Dose CT Scanning

目的探讨剂量指数(DRI)在降低婴幼儿腹部CT扫描辐射剂量的作用及最适合腹部的iDose^(4)算法权重。方法搜集行腹部CT扫描的1~12个月、13~24个月和25~36个月患儿,采用飞利浦Brilliance 128iCT行数据采集,管电压100 kV,DoseRight技术,对临床预实验组预设6个不同的DRI进行扫描,然后对图像质量和辐射剂量进行分析,得到DRI临界值,采用DRI临界值扫描条件对临床实验组进行扫描,并依据iDose^(4)算法的不同权重,重建出6组图像并对图像质量进行分析。结果临床预实验组1~12个月患儿DRI为9~13时,13~24个月患儿DRI为10~13时,25~36个月患儿DRI为11~13时,图像质量能满足诊断;1~12个月患儿,13~24个月患儿,25~36个月患儿DRI临界值分别为9、10、11;3组患儿的CTDI_(VOL)、DLP及SSDE均随DRI的减小而降低(P﹤0.01)。临床实验组3组患儿在脾区及椎旁肌肉区的SNR均随iDose^(4)权重级数增加而增加(P﹤0.05);1~12个月组和13~24个月组在iDose^(4)权重为3时图像主观评分最高,25~36个月组iDose^(4)权重为4时图像主观评分最高。结论合适的剂量指数结合适当的iDose^(4)权重能够降低儿童腹部CT检查的辐射剂量并保证图像质量。

Objective To explore the effect of DoseRight index(DRI) on reducing radiation dose and the most suitable weight of iDose^(4) algorithm when performing infant abdominal CT scan. Methods Children aged 1-12 months, 13-24 months and 25-36 months were collected, Philips Brilliance 128 iCT was used for data acquisition, the tube voltage was 100 kV and the DoseRight technology was used.Six different DRIs were preset in the clinical pre-experimental group for scanning, and then the image quality and radiation dose were analyzed to get the critical value of DRI.The clinical experimental group was performed with the critical value of DRI,and 6 groups of images were reconstructed according to the different weight of iDose^(4) algorithm, and the image quality was analyzed. Results When the DRI was set to 9-13 for 1-12 months, 10-13 for 13-24 months and 11-13 for 25-36 months of pre-experimental group, the image quality could meet the diagnostic needs;the critical values of DRI were 9,10 and 11 in children aged 1-12 months, 13-24 months and 25-36 months, respectively;CTDI_(VOL),DLP and SSDE decreased with the decrease of DRI in all ages of pre-experimental group;SNR in spleen and paravertebral muscles increased with the increase of iDose^(4) weight in all ages of pre-experimental group;in 1-12 months and 13-24 months when iDose^(4) weight was 3,and in 25-36 months when iDose^(4) weight was 4,the highest subjective image scores were obtained. Conclusion Appropriate DRI combined with the appropriate weight of iDose^(4) can reduce the radiation dose of children’s abdominal CT examination and ensure the image quality.