[Quality assurance of mammography in the province of Trent].

In 1991, a second program for quality control in mammography was carried out in the Physics Department of the Trento Hospital. All the six mammographic centers around Trento entered the study and 9 mammographic units were thus considered. Two main types of measurements were obtained: a) determination of the physical variables affecting radiologic system optimization; b) evaluation of image quality and average breast dose, according to DQM program criteria. The film variables, mean gradients and base plus fog level, the half-value layer (HVL) and the entrance exposure free in air were scored as acceptable in all cases. The average breast dose was calculated on the basis of literature data, given the entrance exposure free in air, the HVL and the focus-skin distance values. All the mammographic units but one were scored as "D" (acceptable) on the average breast dose curve, which is defined by the national average value obtained during phase II of the DQM program. This Quality Control program allowed all mammographic units to be optimized and also emphasized the need for periodical quality controls.