Assessment of Skin Entrance Kerma in the United States: The Nationwide Evaluation of X Ray Trends (NEXT)

Abstract

The Nationwide Evaluation of X ray Trends (NEXT) is an annual survey programme to estimate national skin entrance air kerma, free-in-air, for representative diagnostic X ray examinations. It is conducted in the United States cooperatively between the federal government's Food and Drug Administration (FDA) and the various state and local governments through the coordinating agency known as the conference of Radiation control programme Directors (CRCPD). NEXT originally began in 1973 and in 1983 it underwent a major change; limiting the annual survey to one examination, using standard attenuation phantoms for the measurement of exposure, empirically evaluating film processing, and the collection of comprehensive technical data such as tube potential, half-value layer (HVL), type of film screen grid, and optical density of the resulting phantom radiograph. Surveys have been performed for chest radiography (1984 and 1986), the abdomen and lumbosacral spine examination (1987 and 1989), mammography (1985 and 1988), computerised tomography (CT) (1990), and currently fluoroscopy (1991). The mammography and fluoroscopy examinations differ from the other surveys by incorporating image quality test objects.