Experimental Evaluation of a Portable Indirect Flat-Panel Detector for the Pediatric Chest: Comparison with Storage Phosphor Radiography at Different Exposures by Using a Chest Phantom

Abstract

To compare the exposure dose requirements and performance of a portable indirect flat-panel detector for pediatric use in the depiction of catheters, simulated pulmonary nodules, and simulated interstitial lung disease with those of storage phosphor radiography. Catheters and simulated nodules and subtle interstitial lung disease (miliary, reticular, linear, and ground-glass patterns) were superimposed over an anthropomorphic chest phantom. Images were obtained with different exposures corresponding to simulated speeds of 400 and 800 with a portable flat-panel detector and printed on hard copies. These images were compared with those from storage phosphor radiography at a simulated speed of 400, which is typically used in pediatric radiology. Four independent readers recorded 7200 observations per pattern (for a total of 600 statistically independent observations), and these observations were subjected to receiver operating characteristic (ROC) analysis. Differences were considered significant at a P value of .05. Catheters over obscured chest areas, nodules 10 mm or smaller and larger than 10 mm over lucent lung, nodules 10 mm or smaller over obscured chest areas, and miliary and linear patterns over lucent lung showed higher areas under the ROC curve (A(z)) with the flat-panel detector at 400 and 800 digital speed compared with storage phosphor radiography. A(z) values for reticular and ground-glass patterns with the flat-panel detector were equal to or less than those with storage phosphor radiography. These differences, however, were not statistically significant. In the detection of catheters, nodules, and almost all interstitial lung disease, A(z) values were higher with the portable flat-panel detector than with storage phosphor radiography at equivalent and reduced speeds. These results suggest that the portable flat-panel detector could be used with reduced exposure dose in pediatric patients.