Effect of delay between erasure and image acquisition in CR

The effect of time delay between last erasure and image acquisition using computed radiography (CR) image plates (IPs) was investigated using an Agfa ADC Compact CR system.

IPs of various sizes were erased by the IP processing cycle of the CR system. These IPs then were stored in their normal storage place for various durations, ranging from 0 hours to 168 hours. The IPs then were processed, and dark noise images were obtained. The dark noise in each plate was estimated by measuring the average pixel value in several places on the image. Statistical analysis was carried out using 1-way analysis of variance and Kruskal-Wallis testing for any significant differences in dark noise between time delays at P = .05. Regression analysis was carried out to test any relationship between dark noise and time delay.

Statistically significant (P < .05) increases in dark current were observed when the time delay increased, with increase greater than 40% for time delays more than 24 hours. In the short term (< 1 hour), a quadratic relationship was observed, and in the long term (> 24 hours) a linear relationship was observed between dark current and time delay.

Dark noise increases with time delay, and it is useful to erase the IP before image acquisition if time delays of more than 24 hours are experienced, such as over a weekend.