Static lag refers to a ghost image caused by residual latent image from previous exposure.

• A. Only in digital detectors
• B. False
• C. Only in film-screen systems
• D. True

Answer: (D)

Static lag is a ghost image that shows up on a radiograph because some of the latent image from a prior exposure remains on the receptor. After exposure, energy is stored in the receptor material and fades gradually rather than disappearing instantly. If a new exposure occurs before that stored energy fully decays, the residual signal from the previous image adds to the new one, producing a faint overlay. This can happen with film-screen systems and with radiography plates (CR) as well as, to a lesser extent, in digital detectors. So the statement is true: a ghost image can result from residual latent image from a previous exposure.