Original Jpn J Radiol Technol 2000 ; 56 (1) : 95-102
Assessment of Digital Radiography System for Chest Radiography
with RbBr:Tl+ Photostimulable Storage Phosphors

HIDEMICHI KAWATA, RUMI YAMAGATA,1) SUNAO OOKURA, RYUUJI IKEMATSU, SEIJI OOKUBO, HIDEFUMI KUROKI, HITOSHI TANIGAWA,
SEIJI KAWAMURA, NORITADA NAKASHIMA, KIMINORI FUJIMOTO,2) NORIYOSHI UMEZAKI,2) and NAOFUMI HAYABUCHI2)
Center for Diagnostic Imaging, Kurume University Hospital
1)Center for Imaging, Kurume University Medical Center
2)Department of Radiology, Kurume University School of Medicine
Received March 12, 1999; Revision accepted Oct. 12, 1999; Code No. 254
Summary
Observer performance experiments were performed with a digital radiography system (Regius model 330: DR system)using photostimulable storage phosphors (RbBr:Tl+)and a conventional screen-film system (HGM-UR1: S-F system)for chest radiography. A phantom lung with simulated opacities was used (nodule, miliary opacity, consolidation, and reticular opacity), and was exposed with the DR system (sampling distance: 175µm, 2,048 x 2,048 pixels, 12 bits)and S-F system under the same conditions of exposure. Eight physicians with 10 years of almost daily practice in interpreting chest radiographs evaluated the visibility of the simulated opacities and ranked them. The ranking data were analyzed by means of normalized ranked data and the scoring method. Statistical analyses were performed by two-way analysis of variance (ANOVA)and the least significant difference (LSD)method with Studentized t-value, and the confidence coefficients of the ranking were calculated. Evaluation of the visibility of simulated opacities in the lung field showed that the chest radiographs obtained with the DR system using THX2 (look-up table: LUT for chest radiography)were equal to or better than those obtained with the S-F system. In conclusion, the DR system (THX2 with LUT)is a highly useful modality for chest radiography because of its superior performance in comparison with the S-F system under the radiographic conditions used in this study.
Key words: Chest radiography, Digital radiography(DR), Photostimulable storage phosphor, Normalized ranked data