Scatter-Reduction Characteristics of an Infinity-Focused Gridded Radiographic Cassette

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