[The Dosage and Quality of Imaging program and quality assurance in mammography]

The aim of the optimization program for mammography (DQM) in Italy is to achieve the best compromise between image quality and dose to patient. 272 centers agreed to the second phase of the program, from February 1987 to January 1990. Exposure, half-value layer (HVL) and focal spot size were measured according to the same methods employed in the first phase of the DQM program (1985), while image quality was evaluated by means of a new performance phantom. The average exposure was 0.96 R (2.48 x 10(-4) C/kg); in 173 (64.3%) centers exposure was less than 1 R (2.58 x 10(-4) C/kg), and only in 3 centers, where a direct X-ray film was employed, was exposure greater than 5 R (12.9 x 10(-4) C/kg). In every center the average whole-breast dose to a reference organ (5 cm thick, composed of 50% fat + 50% water) was calculated on the basis of entrance exposure, HVL, and focus-skin distance; in 63.2% of the centers doses less than 0.15 cGy were employed. The results allowed dose and image quality to be correlated in order to divide the centers (using a film-screen system) into groups with a different efficiency level: in 101 centers dose and image quality were good, in 64 centers too high a dose was employed, in 66 centers image quality was poor, and in 38 centers dose was too high and image quality was poor. It must be stressed that the DQM program can play its role only if each center carries out its Quality Assurance activity after the methods recommended by the World Health Organization.