SCATTER-REDUCTION CHARACTERISTICS OF AN INFINITY-FOCUSED GRIDDED RADIOGRAPHIC CASSETTE

RATIONALE AND OBJECTIVES. The scatter-reduction properties of a new in finity-focused grid incorporated into a radiographic imaging cassette were analyzed. METHODS. A polystyrene chest phantom was imaged using t he cassette and bedside radiographic procedure. Scatter fractions were measured using a beam-stop technique at several anatomically equivale nt locations. The performance of this cassette also was evaluated as a function of the orientation angle. RESULTS. The gridded cassette prov ided a decrease in scatter fraction from 61% to 49% in the lung and fr om 87% to 76% in the mediastinum. To obtain equivalent film density wh en the grid was used, the exposure was increased by a factor of 3.0. W hile there was a decrease in scatter clean-up as the film cassette was tilted from the perpendicular, the grid performed well out to an angl e of 10 degrees. CONCLUSION. The gridded cassette for portable radiogr aphy provides scatter reduction with little sensitivity to alignment. The availability of this device could improve scatter rejection, and t herefore, contrast in portable radiographic imaging.