Fewest different prime factors Since no S-number is a power of 3, the theoretical minimum is 2 in the form [3.
The largest prime whose square divides a S-number is 9043 in D1 above.
362880 ways, so that there are that many different S-numbers ranging from 123456789 = [3.
Fewest prime factors The theoretical minimum of 3 is found for all S-numbers of form [3.
Roundest numbers The seven roundest S-numbers I have found are:(i)
It will be seen that G2 is twice G1, and there are other pairs of S-numbers which are similarly closely related.
If the average incident exposure on the image receptor is too high or too low, the CR system will make an adjustment and the exposure index or S-number will reflect the adjustment.
Other factors, such as positioning and centering, can affect the S-number value, yet when these factors are held constant, the S-number reflects adjustments for technique exposure errors.
Manufacturers of CR equipment are beginning to address the potential problem of S-number variability.
As with the Fuji S-number, there is concern regarding the consistency of the exposure index.
Tolerance limits for S-number variability are not specifically addressed in the draft document, although the AAPM recommends that linearity of the reader response to the IP exposure should correlate within 10%.
The manufacturer does not provide an expected S-number when using the suggested technical factors.