体型特异性剂量估算值在儿童腹部增强CT检查中的应用及对比剂的影响

Application of Size-Specific Dose Estimates in Contrast-Enhanced Abdominal CT Scan in Children and Influence of Contrast Agent on It

目的探讨体型特异性剂量估算值(SSDE)在儿童腹部增强CT检查中的应用,并分析对比剂的影响。资料与方法回顾性分析2018年10月—2020年12月于南京医科大学附属儿童医院行腹部增强检查的221例患儿,根据年龄分为0~3岁、4~6岁、7~10岁、11~14岁组,记录其年龄及容积CT剂量指数(CTDIvol);手动测量平扫期、动脉期及静脉期图像最中间层面图像的前后径(AP)、左右径(LAT)、兴趣区面积(AROI)及面积内CT值(CTROI),计算有效直径(DE)和水当量直径(DW),基于DE、DW的转换因子(fDE、fDW)及基于DE、DW的SSDE(SSDEDE、SSSDEDW);分析CTDIvol、SSDEDE、SSSDEDW间的差异及对比剂引入前后DW间的差异。结果各分组组内CTDIvol、SSDEDE、SSDEDW差异均有统计学意义(P<0.05)。平扫期4组患儿SSDEDW比CTDIvol分别高117.65%、105.97%、83.24%、70.49%;动脉期4组患儿SSDEDW比CTDIvol分别高132.73%、117.98%、92.03%、73.98%;各分组DW在平扫期、动脉期、静脉期间差异无统计学意义(P>0.05),fDE、fDW组内差异在0~3岁、4~6岁、7~10岁组有统计学意义(P<0.01),在11~14岁组无统计学意义(P>0.05),fDE、fDW随年龄增加而减小。结论CTDIvol低估了患儿的辐射剂量,使用SSDEDW能更好地反映真实辐射,特别是婴幼儿。DW在对比剂引入前后差异无显著变化。

Purpose To explore the application of size-specific dose estimation(SSDE)in pediatric abdominal contrast-enhanced CT examinations and the impacts of contrast agent on it.Materials and Methods A total of 221 children underwent abdominal enhancement CT examinations were retrospectively analyzed,and were divided into four groups according to ages:0-3,4-6,7-10 and 11-14 years old groups.The age and volume CT dose index(CTDIvol)were recorded.The anterior-posterior diameter(AP),lateral diameter(LAT),area(AROI)and CT value within area(CTROI)of the middlemost scanned image were manually measured.The effective diameter(DE),water equivalent diameter(DW),conversion factor(fDE,fDW)and SSDE(SSDEDE,SSSDEDW)were calculated.The differences of CTDIvol,SSDEDE,SSDEDW and the differences of DW before and after the introduction of contrast agent among the four groups were statistically analyzed.Results There were statistically significant differences in CTDIvol,SSDEDE and SSDEDW among the four groups(P<0.05).In the non-contrast scans,the SSDEDW of four groups was 117.65%,105.97%,83.24%and 70.49%,respectively,which were all significantly higher than those of CTDIvol.In the arterial-phase scans,SSDEDW of the four groups was 132.73%,117.98%,92.03%and 73.98%,respectively,which was significantly higher than that of CTDIvol.There were no statistically significant differences in DW among four groups during the non-contrast and arterial and venous phases(P>0.05).The differences of the fDE and fDW within groups were statistically significant in the 0-3 years old,4-6 years old and 7-10 years old groups,but not in the 11-14 years old group.The fDE and fDW decreased with ages.Conclusion CTDIvol underestimated the radiation dose of children,and the true radiation can be better reflected via SSDEDW,especially in infants and young children.No significant changes in DW are identified before and after the introduction of contrast agents.