Neurologic computed tomography in a defined population group.

A total of 766 residents of Olmsted County, Minnesota, underwent neurologic computed tomography (CT) from June 1973 through 1976; 981 scans were performed. The number of CT scans per 1,000 population increased each year and, during the period studied, the average rate based on the initial scan in each case was 2.4 and the rate based on all scans was 3.1. The age-specific rates were greatest among patients 65 years old or older. If CT use plateaus at about 6 scans per 1,000 population, then under conditions similar to those in this community, a population of approximately 400,000 would be required to assure adequate use of a CT scanner for investigating neurologic disease.