CT with a computer-simulated dose reduction technique for detection of pediatric nephroureterolithiasis: comparison of standard and reduced radiation doses.

OBJECTIVE: The purpose of this study was to compare the diagnostic capabilities of standard- and reduced-dose CT in the detection of nephroureterolithiasis in children. MATERIALS AND METHODS: Forty-five patients 20 years old or younger divided into two groups weighing 50 kg or less and more than 50 kg underwent unenhanced 16-MDCT in the evaluation of acute flank pain. An investigational computer-simulated tube current reduction tool was used to produce additional 80- and 40-mA examination sets (total number of image sets=135). Three independent blinded readers ranked random images for stones (confidence scale, 1-5, least to most), hydronephrosis, noise-based image quality, and presence of nonrenal lesions. RESULTS: Compared with the standard tube current used for the original CT scans, there was no significant reduction (p=0.37) in detection of renal stones at the 80-mA setting (mean dose reduction, 67%; range, 43-81%); and at the 40-mA setting (mean dose reduction, 82%; range, 72-90%), the detection rate was significantly lower (p=0.05). At the 40-mA setting, there was no significant difference among the children weighing 50 kg or less (p=0.4). Detection of ureteral stones and hydronephrosis was not significantly different at 80 and 40 mA; however, disease frequency was low, and no definite conclusion can be made. CONCLUSION: Simulated dose reduction is a useful tool for determining diagnostic thresholds for MDCT detection of renal stones in children. Use of the 80-mA setting for all children and 40 mA for children weighing 50 kg or less does not significantly affect the diagnosis of pediatric renal stones.

Duke Scholars

Author Donald Paul Frush Radiology, Pediatric Radiology

Author Charles Mason Maxfield Radiology, Pediatric Radiology