ABSTRACT
The availability of computed radiography has opened the possibility of using reduced dosage for radiographs in clinical settings and reducing the retake rate. A prospective controlled study was carried out over a period of four months comparing conventional X-rays and computed radiography. The aim was to assess if computed radiography at 50% normal dosage would result in films of adequate quality and a reduced retake rate compared to conventional radiography. The number and reason for retakes in each group were recorded. Film quality comparison using only chest X-rays (CXR) in one of three positions; erect posterior-anterior (PA), anterior-posterior (AP) sitting and supine was done by a panel of radiologists.
A total of 6373 conventional and 4127 digital films were analysed. The overall retake rate was lower in the computed radiography group (4.6 vs 8.2% P <0.001) as was the retake rate due to exposure factors (0.6% vs 3.2% P <0.01). There was a higher proportion of optimal films in the computed radiography group for erect PA and sitting AP CXR (71% vs 61% P = 0.0015 and 64% vs 9% P = 0.0009 respectively) but no difference for supine films. Computed radiography resulted in a reduced retake rate due to exposure factors leading to a reduction in the overall retake rate. Despite 50% dosage reduction, films were of better or equal quality when compared to conventional radiography.New computed radiography imaging systems are slowly gaining a foothold in radiological departments worldwide. By computed radiography we mean a digital imaging system which exposes a photostimulable phosphor image receptor plate to obtain a latent image using existing radiographic equipment.
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