A trial of duplicating film for mammography

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When reporting mammograms it is essential that comparisons, where possible, are made with the patient's previous examinations. NHS breast screening units do not routinely release original mammograms to other sources for reporting comparisons. The quality of duplicate mammograms varies enormously. One of the factors associated with this variation is the type of duplicating film used. A trial of five leading film manufacturers duplicating film (Agfa, Fuji, Kodak, Konica and Sterling) was undertaken. Sensitometry tests were carried out and duplicates of Tor Mas, Tor Mam and mammograms of different breast types were produced and scored. The results from the Tor Mam test were inconclusive, while the scores from the Tor Mas and mammograms showed marked differences between the makes of duplicating film. Characteristic curves for all duplicates and the original film were drawn. The gamma of each film was calculated and ranged from 3.25 to 5.07. A one-sample t-test was carried out on the data from the characteristic curves to look for a statistical difference between the duplicate films and the original. P values ranged from 0.27 to 0.0005 with P < 0.01 being statistically significant. Kodak duplicating film performed well in all tests, Fuji and Sterling scored poorly.