title: Comparison of anti-scatter grids for digital imaging with use of a direct-conversion flat-panel detector.
abstract: Our purpose in this study was to establish a selection standard for anti-scatter grids for a direct conversion flat-panel detector (FPD) system. As indices for grid evaluation, we calculated the selectivity, Bucky factor, and the signal-to-noise ratio improvement factor (SIF) by measuring rates of scatter transmission, primary transmission, and total transmission (based on the digitally displayed measurement values of the FPD system), using 4 acrylic phantoms of different thicknesses. The results showed that the SIF was less than 1.0 when the phantom thickness was 5 cm. When the phantom thickness was 25 cm and the grid ratio was 16:1, the SIF was 1.505 and 1.518 (maximum value) at 90 and 120 kV, respectively. Compared with the grid ratio of 12:1, the SIF at the grid ratio 16:1 was improved by 6.1% at 90 kV, and by 7.0% at 120 kV. In a direct-conversion FPD system, the grid ratio of 16:1 is considered adequate for eliminating the scattered-radiation effect when much scattered radiation is present, such as with a thick imaged object or a high X-ray tube voltage.
authors.affiliation: Department of Radiology, University Hospital, Kyoto Prefectural University of Medicine, 465 Kajii-cho, Kawaramachi-Hirokoji, Kamigyo-ku, Kyoto 602-8566, Japan. mizuta3@koto.kpu-m.ac.jp
authors.forename: Masayoshi
authors.initials: M
authors.lastname: Mizuta
authors.forename: Shigeru
authors.initials: S
authors.lastname: Sanada
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Akazawa
authors.forename: Toshifumi
authors.initials: T
authors.lastname: Kasai
authors.forename: Shuji
authors.initials: S
authors.lastname: Abe
authors.forename: Yasuhiro
authors.initials: Y
authors.lastname: Ikeno
authors.forename: Shigeki
authors.initials: S
authors.lastname: Mitou
mesh_terms: D012542:Scattering, Radiation; D059629:Signal-To-Noise Ratio; D014057:Tomography, X-Ray Computed / Q000295:instrumentation*