Under what circumstances should I establish a new baseline optical density (OD) operating level?
A new baseline OD operating level may need to be established when switching to a new type of film or if the AEC density selector settings in the mammographic unit have been re-calibrated during servicing of the unit. Before changing operating levels, check that there isn’t an underlying problem that needs to be corrected. A new level may be established if the interpreting physician(s) has/have made an intentional decision to modify background optical densities of the clinical images. For example, many facilities are choosing to increase film density to take advantage of the film’s increased contrast at higher ODs. (See When performing the weekly phantom QC test, should we use film from the box currently being used to produce clinical exams or film from the box used for quality control purposes?)