Radiographic Optical Density Under Automatic Exposure Control and Comparison with the EC Quality Criteria

As part of a quality control programme in diagnostic radiology, automatic exposure systems in general radiography and mammography have been checked over the years 1996 to 1998. The optical density has been measured of films of standard phantoms exposed under normal clinical conditions, representative of the mean density of clinical films. Approximately 100 general diagnostic systems and 28 mammographic systems, responsible for approximately 1,000,000 patient examinations, were involved. Results show that the mean film density of the lumbar spine films was 1.27 compared to that of 1.62 for the mammographic systems. There was a wide variation in the lumbar spine densities with only 65% meeting the EC Quality Criteria that the target optical density should lie between 1.0-1.4. However over the three years there was a reduction in the range of densities. In mammography, 83% of systems met the recommended target density in the United Kingdom of 1.4-1.8.