Image fade in computed radiography is exacerbated by increased kVp

Processing of Computed radiography image plates involves a time delay between the image acquisition and processing. This delay can vary from 1 to 30 minutes depending on the clinical situation. This study aims to examine the effects latent image fade upon the low contrast resolution of computed radiography images over time and establish whether kVp has an influence on image fade. Three observers assessed the images. Image quality figures were calculated as a measure of contrast detail resolution. Significant reductions in low contrast resolution were seen to occur as the delay between exposure and processing increased. The image quality decreased by 2.8% at 5mins; 6% at 10mins and 8.8% at 20mins. Deterioration then continued at a steady rate until the plateau of 20.7% was reached at 3 hours finally at 15hrs the deterioration was 40.49% compared to the reference image. The rate of this deterioration increased with kVp. At 20mins for 75kVp the low contrast resolution had decreased by 8.8%; at 80kVp it was 9.6%; 10.15% at 85kVp and at 95kVp 16.8%. A substantial decrease in low contrast resolution of CR images result from long delays between exposure time and processing, this is exacerbated by higher kVps. Radiographers will lose at least 8.8% in low contrast resolution of an image with a processing delay of 20 minutes.