Analysis of digital images acquired using different phosphor storage plates (PSPs) subjected to varying reading times and storage conditions

Objectives: To assess, both objectively and subjectively, the effects of different combinations of storage conditions and varying delays in reading on digital images captured using phosphor storage plates (PSPs). Method: Standardized images were obtained of an aluminium step wedge and a dry mandible in acrylic using GE 1000 and PSPs from the Digora((R)) (Soredex) and DenOptix((R)) (Gendex) digital systems. Twelve plates from each system were exposed and immediately scanned to produce the baseline gold standard. The plates were re-exposed and stored using three different storage combinations, (A) ambient temperature, (R) refrigeration and (S) low humidity, and then scanned after 6 h, 12 h, 18 h, 24 h, 48 h or 72 h. Objective analysis was carried out by pixel density measurements and the data were analysed statistically using analysis of variance. Subjective analysis was carried by three oral radiologists and the results were analysed using Mann-Whitney U-test. Results: For the DenOptix((R)) system there were no differences either objectively or subjectively in the images obtained from all the plates using different storage conditions and after varying time intervals. For Digora((R)), objective analysis showed loss of pixel density after 6 h using all storage conditions. This loss of density was also evident subjectively after 6 h on plates stored under certain storage conditions. Conclusion: Storage of DenOptix((R)) PSPs for up to 72 h in different conditions does not affect the quality of the digital images. However, there is a loss of image density within 6 h when using Digora((R)) PSPs, which may affect clinical image interpretation.