[jaden]

Optical film density in film radiography and grey value in CR and DR have some similarities but still they are not same.

When we increase the radiation exposure of film then optical density increases. Similarly increase in exposure results in increase in grey value in CR up to a certain level as determined by bit value. Film follows sensitometric curve which is not a straight line. CR software may have facility to select linear or logarithmic curve. Standard specifies the density range for example ASME Sec V specifies 2 to 4 density range for gamma radiography. But it does not specify required grey value range because by adjusting window-level we can view different range of grey values. Also different equipment/software follows different grey value range.

SNR does not related with optical density. SNR is expected to be high for better digital image quality.

Could you please specify what type of conversion chart you are looking for?