Radiation dose reduction on mutidetector abdominal CT using adaptive statistical iterative reconstruction technique in children

Abstract

Objective To investigate the feasibility to reduce radiation doses on pediatric mutidetector abdominal CT using the adaptive statistical iterative reconstruction technique (ASIR) associated with automated tube current modulation technique (ATCM). Methods Thirty patients underwent abdominal CT with ATCM and the follow-up scan with ATCM cooperated with 40% ASIR.ATCM was used with age-dependent noise index (NI) settings:NI=9 for 0—5 year old and NI=11 for﹥5 years old for simple ATCM group,NI=11 for 0—5 year old and NI=15 for>5 years old for ATCM cooperated with 40% ASIR group (AISR group).Two radiologists independently evaluated images for diagnostic quality and image noise with subjectively image quality score and image noise score using a 5-point scale.Interobserver agreement was assessed by Kap pa test.The volume CT dose indexes (CTDIvol) for the two groups were recorded.Statistical significance for the CTDIvol value was analyzed by pair-sample t test. Results The average CTDIvol for the ASIR group was (1.38±0.64) mGy,about 60% lower than (3.56±1.23) mGy for the simple ATCM group,and the CTDIvol of two groups had statistically significant differences. (t=33.483,P<0.05).The subjective image quality scores for the simple ATCM group were 4.43±0.57 and 4.37±0.61,Kap pa=0.878,P<0.01 (ASIR group: 4.70±0.47 and 4.60±0.50,Kap pa=0.783,P<0.01),by two observers.The image noise score for the simple ATCM group were 4.03±0.56 and 3.83±0.53,Kappa=0.572,P<0.01 (ASIR group:4.20±0.48 and 4.10±0.48,Kappa=0.748,P<0.01),by two observers.All images had acceptable diagnostic image quality. Conclusion Lower radiation dose can be achieved by elevating NI with ASIR in pediatric CT abdominal studies,while maintaining diagnostically acceptable images. Key words: Radiation dosage; Children; Comparative study