Exposure Index, Target Index, and Deviation Index

This is a brief video describing the relationship between EI, TI and DI in a digital radiography lab. The exposure index is calculated by the computer based on the actual exposure (in fractions of a Gray) of the image receptor. The target index is pre-assigned but should be adjusted by the personnel at the clinical site. The deviation index is a logarithmic value based on a comparison between the actual exposure (the EI) and the IDEAL exposure (the TI) which is assigned based on multiple exposures of the same body part. When properly adjusted, these numbers can aid the radiologic technologist in making a properly exposed radiograph.