One of the key advantages of digital systems is the
ability to record the exposure to the receptor. With CR
systems, this value is stored and displayed as a number
related to the amount of the X-ray exposure incident on the
plate. Manufacturers have developed indices for this value
that are unique to their systems (Table 1). Examples include
the Fuji S number, Agfa LGM index, Canon REX value
and various other types of exposure values [6, 8]. These
values respond in different ways to changes in exposure,some increasing with increased exposure and some decreasing
with increased exposure.