COMPARISON OF IMAGE QUALITY AND MEAN ABSORBED DOSE TO THE BREAST FOR 2 MAMMOGRAPHIC FILMS

A film intended for mammography (Kodak SO 155 MRH-1) was tested and co mpared to one (Kodak SO 177 Ortho M) used earlier. Both films includin g the cassette could resolve 20 1p/mm. For a processing time of 90 s t he new film gave the same overall image quality and irradiation dose t o the breast as the old system. If, instead, the processing time was i ncreased to 150 s, a 43% reduction in kerma could be attained with the new film. With a developing temperature of 36-degrees-C and 150 s pro cessing time, the noise is clinically acceptable. A nonparametric test showed no significant difference between the 2 films on the 0.01 leve l. At an X-ray tube potential difference of 25 kV, the mean absorbed d ose to a 4.5-cm-thick breast was reduced from 1.7 mGy with the old com bination to 1.0 mGy with the new one. The measurements were made with a moving grid.