CT with a Computer-Simulated Dose Reduction Technique for Detection of Pediatric Nephroureterolithiasis: Comparison of Standard and Reduced Radiation Doses

• Published in: American journal of roentgenology (1976) Vol. 192; no. 1; pp. 143 - 149
• Main Authors: Karmazyn, Boaz, Frush, Donald P, Applegate, Kimberly E, Maxfield, Charles, Cohen, Mervyn D, Jones, Robert P
• Format: Journal Article
• Language: English
• Published: Reston, VA Am Roentgen Ray Soc 01-01-2009; American Roentgen Ray Society
• Subjects: Adolescent; Applied radiobiology (equipment, dosimetry...); Biological and medical sciences; Biological effects of radiation; Body Burden; Child; Child, Preschool; Female; Fundamental and applied biological sciences. Psychology; Humans; Investigative techniques, diagnostic techniques (general aspects); Kidney Calculi - diagnostic imaging; Male; Medical sciences; Radiation Dosage; Reproducibility of Results; Sensitivity and Specificity; Tissues, organs and organisms biophysics; Tomography, X-Ray Computed - methods; Ureterolithiasis - diagnostic imaging; Young Adult; Human; Nuclear medicine; Pediatrics; Radiodiagnosis; Low dose; Standards; Radiation dose; Radiobiology; Radiology; Medical imagery; Computerized axial tomography; Dosimetry; Technique; Child; Comparative study
• ISSN: 0361-803X; 1546-3141
• DOI: 10.2214/AJR.08.1391

The purpose of this study was to compare the diagnostic capabilities of standard- and reduced-dose CT in the detection of nephroureterolithiasis in children.
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.
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.
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.