PHANTOM STUDY OF CHEST RADIOGRAPHY WITH STORAGE PHOSPHOR, SELENIUM, AND FILM-SCREEN SYSTEMS

Purpose: Chest radiographs from 3 digital systems - 2 based on lumines cent phosphors and one on selenium - and a conventional film-screen sy stem were evaluated and compared. Material and Methods: Computed radio graphy (CR) has for the past years been dominated by a single manufact urer, but now several systems have been marketed. Using a chest phanto m and, as test objects, 2 simulated tumours for the lung and mediastin um, respectively, and one object simulating pulmonary lines, a total o f 400 exposures were made, 100 on each system. The test objects were p laced randomly with a ratio of presence/absence of each object of abou t 50. Six radiologists participated, 2 residents and 4 staff members. A receiver operating characteristics (ROC) analysis was per formed wit h construction of curves, and the difference between the curves was es timated with a 2-tailed paired t-test. Results and Conclusion: The sel enium-based system performed significantly better for pulmonary line d etection than all the other systems, and better than one storage phosp hor system for the lung ''tumour'' (p<0.05), while one storage phospho r system was slightly better than the other in diagnosing all 3 test o bjects. The score for the film-screen system was only average.