Assessment of Digital Radiography System Performance in Radiology Departments in Imo State

The transition from conventional film-screen to digital radiography in Nigerian hospitals offers substantial benefits in image quality, dose efficiency, and workflow, but the performance of installed digital radiography systems in Imo State radiology departments has not been systematically evaluated. This study assesses digital radiography system performance at six hospitals in Imo State with installed computed radiography or direct digital radiography systems. Performance parameters evaluated include spatial resolution (measured by modulation transfer function using a line pair test tool), low-contrast detectability (assessed by Leeds test objects), image noise (expressed as normalised noise power spectrum), detective quantum efficiency, and image processing artefact assessment. System calibration and detector uniformity were verified using flat-field exposure analysis. Dose area product values and exposure index values from clinical chest and pelvis examinations were collected to assess clinical dose efficiency. Results show that spatial resolution performance met manufacturer specifications at four of six systems. Low-contrast detectability was below acceptable thresholds at two systems, indicating detector phosphor degradation in older computed radiography plate readers. Image processing artefacts attributable to dust contamination of computed radiography imaging plates were identified at three facilities, suggesting inadequate plate cleaning protocols. Dose area product values for standard chest examinations were higher than European reference levels at three facilities, indicating opportunities for technique optimisation. The study recommends a structured digital radiography quality assurance programme and regular imaging plate cleaning and replacement cycles at Imo State hospitals. Keywords: digital radiography, image quality assessment, modulation transfer function, radiology, Imo State.