For example, typical ranges of the “S number” developed
by Fuji were 200 to 800 but the value decreased with
increased exposure. Some of these indices change in a
logarithmic fashion and some change in a linear fashion.
Needless to say, there is a confusing variety of indices when
multiple systems are used within a department. The result is
that they might be ignored. Another reason these numbers
have largely been ignored is that the data are acquired on a
case-by-case basis. Acquiring a large number of data points
for a valid QA program would require a tiresome manual
method of tracking and recording the number for each
patient.