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SU‐C‐220‐02: A High Efficiency Grid System for Abdominal Radiography
Author(s) -
Gauntt D,
Barnes G
Publication year - 2011
Publication title -
medical physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.473
H-Index - 180
eISSN - 2473-4209
pISSN - 0094-2405
DOI - 10.1118/1.3611508
Subject(s) - grid , optics , detector , line (geometry) , materials science , computer science , physics , geometry , mathematics
Purpose: To improve scatter control in abdominal radiography.Methods: A crossed grid system was constructed and consists of a stationary low ratio, high strip density conventional grid (8:1, 60 lines/cm) positioned above and with its septa orthogonal to the septa of a novel high ratio, air interspace, coarse strip density scanning grid (15:1, 2.0 lines/cm). The latter has articulating grid slats; during an exposure the slats remain focused on the x‐ray focal spot. To suppress grid line artifacts, a trapezoidal x‐ray exposure was generated and coupled with the movement of the scanning grid. This effectively eliminates grid line artifacts for small grid movements. The grid DQE was measured for 4 grid configurations: the crossed grid system, the scanning grid alone, a stationary 15:1 conventional grid, and no grid. The measurements were made with standard CsI flat panel detector and a variety of acrylic thicknesses and x‐ray tube potentials.Results: In all cases the DQEgrid measured with the various grid systems was markedly better (130% to 580%) than that measured without a grid. The performance of the crossed grid system was 6% to 120% better than the conventional 15:1 grid. The scanning grid system performed 22% better (20 cm acrylic, 60 kVp) to 6% worse (40 cm acrylic, 120 kVp) than the crossed grid system. While subtle gridline artifacts are present in flat‐field images, the artifacts are invisible in images of anthropomorphic phantoms Conclusions: A high efficiency scanning grid system has been designed and constructed. The system requires only a short grid movement during an exposure to suppress grid line artifacts. It can be used with or without a crossed conventional low ratio grid. In either case, its dose efficiency in controlling scatter is markedly superior that of a high quality, high ratio conventional stationary grid. The authors are co‐owners of X‐Ray Imaging Innovations, which has developed this technology, and are co‐inventors of U.S. Patent 6,795,529, which covers this technology