Pediatric MDCT: towards assessing the diagnostic influence of dose reduction on the detection of small lung nodules.
OBJECTIVE
The purpose of this study was to evaluate the effect of reduced tube current (dose) on lung nodule detection in pediatric multidetector array computed tomography (MDCT).


METHODS
The study included normal clinical chest MDCT images of 13 patients (aged 1-7 years) scanned at tube currents of 70 to 180 mA. Calibrated noise addition software was used to simulate cases as they would have been acquired at 70 mA (the lowest original tube current), 35 mA (50% reduction), and 17.5 mA (75% reduction). Using a validated nodule simulation technique, small lung nodules of 3 to 5 mm in diameter were inserted into the cases, which were then randomized and rated independently by three experienced pediatric radiologists for nodule presence on a continuous scale ranging from zero (definitely absent) to 100 (definitely present). The observer data were analyzed to assess the influence of dose on detection accuracy using the Dorfman-Berbaum-Mets method for multiobserver, multitreatment receiver-operating characteristic (ROC) analysis and the Williams trend test.


RESULTS
The areas under the ROC curves were 0.95, 0.91, and 0.92 at 70, 35, and 17.5 mA, respectively, with standard errors of 0.02 and interobserver variability of 0.02. The Dorfman-Berbaum-Mets method and the Williams trend test yielded P values for the effect of dose of .09 and .05, respectively.


CONCLUSIONS
Tube current (dose) has a weak effect on the detection accuracy of small lung nodules in pediatric MDCT. The effect on detection accuracy of a 75% dose reduction was comparable to interobserver variability, suggesting a potential for dose reduction.
Li
Xiang
X
Medical Physics Graduate Program, Department of Radiology, Duke University, 2424 Erwin Road, Suite 302, Durham, NC 27705, USA.
Samei
Ehsan
E
DeLong
David M
DM
Jones
Robert P
RP
Gaca
Ana Maria
AM
Hollingsworth
Caroline L
CL
Maxfield
Charles M
CM
Colsher
James G
JG
Frush
Donald P
DP
D001822:Body Burden; D002648:Child; D002675:Child, Preschool; D006801:Humans; D007223:Infant; D008175:Lung Neoplasms / Q000000981:diagnostic imaging*; D008297:Male; D010372:Pediatrics / Q000379:methods; D011829:Radiation Dosage; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D003074:Solitary Pulmonary Nodule / Q000000981:diagnostic imaging*; D014057:Tomography, X-Ray Computed / Q000379:methods*