Conversion Of A Radiology Department To Rare-Earth Screen-Film Systems

The Department of Radiology at Jackson Memorial Hospital performs 204,000 x-ray examinations per year involving 816,000 x-ray films. When it became necessary to replace a large percentage of existing screens we decided that, in view of the large potential saving in radiation dose to the community, the conversion to Rare-Earth Technology had to be considered. The size and complexity of this department makes it difficult to attempt a piecemeal conversion and therefore a combination phantom-patient study was undertaken to determine what - if any - compromises in image quality would be necessary to achieve significant dose reduction. Pelvic phantom images were produced at the same kVp, mA and identical film density (at a predetermined spot) utilizing 34 different film-screen combinations at surface exposures ranging from 55 mR to 650 mR. Radiologists in the department were asked to rank the films, blind, (including a sample of the system in use at that time, i.e. Dupont Hi-Plus Screens and 3M Type R Film) for contrast, sharpness, noise and overall subjective image quality on a scale of 1-5. The dependence of image quality on kVp was examined by taking phantom images of selected film-screen systems at 70, 90, and 110 kVp. These were ranked in a similar way. Simultaneous to the above phantom study, selected film-screen combinations were used for various routine diagnostic examinations to establish whether or not x-ray techniques could be adjusted to produce acceptable diagnostic image quality using Rare-Earth Systems in the entire department.