There are two issues relating to daylight systems, namely: darkroom fog and the artifact evaluation test in the physicist survey. Darkroom Fog is addressed below. The other issue is addressed in the "Artifact Test for Daylight Processing Systems" guidance policy.
Darkroom Fog: First, if the facility has a darkroom which is used routinely for other diagnostic work but is used occasionally for mammography for loading the magazines in the daylight system, the argument has been raised that since the loading operation may effect only the first and last film in a box, there may be justification to raise the value of the action level for the darkroom fog test and not hold the facility accountable for the daily QC maintenance. Second, if the facility does not have a darkroom at all, how should the fog test be conducted, if at all.
Since excessive fog can adversely affect mammographic image quality, the place where daylight system magazines are loaded, whether it is a darkroom, a closet, or any other room used for this purpose, should be held to the same fog standard regardless of the number of images that may be affected. The following is the FDA policy on this issue:
- If the facility has a darkroom for magazine loading, this room should be checked for darkroom fog during the inspection. The facility should also have QC records for darkroom fog.
- If the facility does not have a darkroom but uses another enclosure for magazine loading, that enclosure should be tested during the inspection for fog levels under magazine loading conditions as if it were a "darkroom." However, the facility does not have to conduct QC testing for darkroom fog.