Delay in the processing of photostimulable phosphor storage plates (PSP) is a common occurrence in crowded clinics. Accordingly, the effects of processing delays in different coverages on the image quality of photostimulable PSPs were investigated with Acteon and Digora scanners. Methods: Three Acteon (group A) and three Digora (group B) PSPs were used in this in vitro study. Each group had three subgroups according to three coverages, including protective box (A1 , B1 ), semitransparent (A2 ,

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... 2 ), and original dark case plates (A3 , B3 ). An aluminum step wedge was subjected to constant exposure conditions. The exposed plates were immediately processed with their corresponding scanner device (the golden standard), 5, 10, 20, 30, 40, and 60 minutes after exposure. The average gray level information of the 2nd, 5th, and 8th steps of the Al wedge was considered as the mean gray values (MGVs) of each wedge. The difference between the gray values of the 8th and 2nd steps was measured as image contrast. Results: There was a significant difference between the contrast and MGVs of Acteon and Digora PSPs at all processing delay times (P<0.05). In general, there was no significant difference in the image MGVs and contrast between subgroups in any of the scanners (total P>0.05). In each subgroup, MGVs increased, while contrast decreased by increasing the processing delay time; the difference was significant except for the MGVs in the first 5 minutes of A1 (P=0.12) and A3 (P=0.06). Conclusions: Thus, the type of scanner was effective on image quality; the type of PSP coating in the first few minutes could affect the rate of image quality loss. However, the scan time had a greater effect on the amount of image loss.