Latent image fading in mobile mammographic screening

Abstract

I should like to comment in support of the letter by Robson et al (1992) and to provide further data on this topic, which is one of some concern to Breast Screening Programmes in remote areas. The film–screen system used in the Edinburgh Breast Screening Centre at the start of the national screening programme was Fuji NH film with Fuji Hi-Mammo screens and cassettes. This system was tested for latent image fading in July 1989, when 24 radiographs of a “Baits” phantom (White & Tucker, 1980) were obtained in under 1 h. The X-ray exposures were made on a Siemens Mammomat 2S unit in a screening van. This X-ray unit was chosen in preference to the units then available at the Centre because of the high reproducibility of its X-ray output. Of these 24 films, six were processed about 1 h after exposure (the shortest practicable time), six after a further 24 h, six at 1 week after exposure and the last six at 3 weeks after exposure. The mean background density of each set of six films is given in Table I, after correction for small changes in sensitometry speed index of the processor.