Orhan H. Suleiman

Managing Radiation Use in Medical Imaging: A Multifaceted Challenge

This special report aims to inform the medical community about the many challenges involved in managing radiation exposure in a way that maximizes the benefit-risk ratio. The report discusses the state of current knowledge and key questions in regard to sources of medical imaging radiation exposure, radiation risk estimation, dose reduction strategies, and regulatory options.

Radiation protection requirements for medical x‐ray film

Previous darkroom shielding requirements for medical x-ray film-assumed that the film should not be exposed to diagnostic x-ray radiation levels greater than 2 microGy (0.2 mR) for the life of the film. Modern medical x-ray films are much less sensitive to ionizing radiation, with most films showing at least an order of magnitude less sensitivity than previously assumed. Conversely, these same films when loaded in cassettes using modern intensifying screens exhibit an order of magnitude greater sensitivity when these cassettes are exposed to ionizing radiation. These data suggest that protection of modern medical x-ray film, stored in a darkroom, may require less shielding than previously assumed. Conversely, film loaded in a cassette will require greater shielding.

A Comparison of Freshly Exposed and Preexposed Control Film in the Evaluation of Processing

In order to determine the relative effectiveness of improperly stored, preexposed sensitometric film in the evaluation of processing during a several month period of time, a comparison was made of medical x-ray film which was exposed with a light sensitometer and immediately processed (freshly exposed) and film that had been exposed with a light sensitometer at an earlier time (preexposed) and processed along with the freshly exposed film. The freshly exposed and preexposed films were further divided into a properly stored group, in our darkroom, and an environmentally stored group. The environmentally stored films were kept in a light-tight box in the trunk of a car during the months of August through October, 1983, and August through September, 1984. Each sample set of data included (1) properly stored and freshly exposed film, (2) properly stored and preexposed film, (3) environmentally stored and freshly exposed film; and (4) environmentally stored and preexposed film. A complete set of films was processed at specific times during the study. Initially the time interval for processing between two consecutive sample sets was measured in minutes, with this time interval increasing to hours, days, and weeks. The last sample set was processed 70 days after the study began. Density differences as large as 0.70 between the freshly exposed and preexposed films were observed. A second trial was conducted in order to repeat some of our earlier observations. Two additional film types were incorporated into the second trial. Observations will be discussed along with implications for quality assurance test procedures.