Investigation of optimal display size for detecting ground-glass opacity on high resolution computed tomography using a new digital contrast-detail phantom.
The purpose of this study was to clarify the relationship between display sizes of high resolution computed tomography (HRCT) images for detecting ground-glass opacity (GGO) and observer performance using a digital contrast-detail (d-CD) phantom. A structure of the d-CD phantom was determined on the basis of the actual images of GGOs and background noises of 22 patients who were diagnosed as GGO by chest HRCT. The d-CD phantom has a 512×512 matrix in size and has total of 100 holes: the diameter of these holes increases stepwise from 2 to 20 pixels with 2 pixels interval in a vertical direction and the CT value varies stepwise from 2 to 200 HU in a horizontal direction. The observer performance study was carried out for three different display sizes (30 cm×30 cm as an enlarged size, 13 cm×13 cm as an original size, and 7 cm×7 cm as a reduced size) using a 2-megapixels LCD monitor, and it was analyzed using Friedman and Wilcoxon statistical tests. As a result, the observer performance for the original display and the reduced display sizes was superior to that for the enlarged size (P=0.006 and 0.037 for the original display and the reduced display sizes, respectively), whereas there was no significant difference between the original display and reduced display sizes (P=0.77). The d-CD phantom enables a short-term evaluation of observer performance and is useful in analyzing relationship between display size and observer performance.
Yamaguchi
Michihiro
M
Department of Radiology, Osaka Prefectural Medical Center for Respiratory and Allergic Disease, Osaka Prefectural Hospital Organization, and Department of Medical Physics and Engineering, Graduate School of Medicine, Osaka University, 3-7-1 Habikino, Habikino City, Osaka 583-8588, Japan. yamaguchim@opho.jp
Fujita
Hideki
H
Bessho
Yuichi
Y
Inoue
Tatsuro
T
Asai
Yoshiyuki
Y
Murase
Kenya
K
D003626:Data Display; D004867:Equipment Design; D019544:Equipment Failure Analysis; D006801:Humans; D008175:Lung Neoplasms / Q000000981:diagnostic imaging*; D019047:Phantoms, Imaging; D011856:Radiographic Image Enhancement / Q000295:instrumentation*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014057:Tomography, X-Ray Computed / Q000295:instrumentation*