RadioGraphics, Vol 17, 177-187, Copyright © 1997 by Radiological Society of North America
Technical aspects of screen-film radiography, film processing, and quality control
JE Gray
Department of Diagnostic Radiology, Mayo Clinic and Foundation, Rochester, MN 55905, USA.
The broad goal of quality control (QC) of screen-film radiography and film
processing is to provide radiographs of consistent, high quality.
Achievement of this goal requires attention to several areas, including QC
of the screen-film system and photographic processor, acceptance testing of
all components, and skill in analysis of film artifacts to "diagnose" the
processor problems causing the aberrations. Methods to reduce waste,
recycle by-products, and reuse resources such as silver are also part of
the QC process. To optimize the photographic process, one should use the
film, chemical solutions, processor, and screens and cassettes produced by
one manufacturer or the combination recommended by the film manufacturer.
Important variables in film processing (eg, density, density difference,
and base plus fog) are recorded on control charts, which plot the variables
as a function of time and allow easy analysis of changes in operating
levels. Many variables can affect any component in the screen-film imaging
system; problems caused by manufacturing batch-to-batch variation, which is
perhaps the most pervasive variable, can be lessened by purchasing film,
screens, and cassettes in large batches and of the same batch and by
purchasing photographic chemicals in concentrated form and mixing them as
needed. Acceptance testing ensures that the product meets expectations,
ensures that its performance meets specifications, and establishes the
operating level for the ongoing QC program.
