ISO 18939:2013 establishes test methods for measuring the stability of photographic films intended for storage of medical records. It is applicable to greyscale images on films for use in transmission mode that are based on thermally processed materials (photothermography, thermography, microcapsule) or created by inkjet printing. Thermally processed materials have a base of safety polyester [poly (ethylene terephthalate)] and work predominantly with silver behenate salts dispersed in non-gelatinous emulsions or dye-based microcapsule emulsions that are thermally processed to produce a black-and-white image. In inkjet printing ink droplets are jetted onto a film with an ink-receiving layer to produce a greyscale image.
ISO 18939:2013 does not cover wet-processed black-and-white films or black-and-white paper. It is not applicable to medical colour images or colour prints created by colour inkjet or dye diffusion thermal transfer (D2T2). Neither does it cover medical greyscale images printed on reflective materials for referral purposes or filmless systems such as picture archiving and communication systems (PACS) in medical imaging.
ISO 18939:2013 requires the arbitrary choice of "illustrative end points" for changes in colour and perceived contrast to depict quantifiable changes due to physical ageing. Extrapolations based on ?illustrative end points' do not have any proven diagnostic or clinical relevance due to the lack of corresponding statistically significant scoring by radiologists.