title: [Evaluation of low-contrast detectability in low-dose chest computed tomography].
abstract: We investigated whether low-contrast resolution evaluation can be applied to chest (lung field) computed tomography (CT) images that are commonly reconstructed using filter kernels with strong frequency emphasis and displayed at wide window widths. We assumed low dose chest CT examinations and set the current-time product to 5 and 10 mAs. The visual detection study was performed by five radiological technologists using water phantom images in which the simulated low contrast objects (disc objects) were implanted. In addition, values of the low contrast detectability index (LCDI) based on a signal-to-noise ratio theorem were calculated from the modulation transfer factor, noise power spectrum, and the object's spectrum for each combination of object size, contrast, current-time product, and kernel. The detectability results correlated well with the LCDI values and correlated less well with the contrast-to-noise ratio results. These results were consistent with the results of past reports on abdomen images. Therefore, our results indicated that low contrast sensitivity can be applied to chest CT images as well as abdominal ones.
authors.affiliation: Department of Radiology, Hannan City Hospital.
authors.forename: Yohei
authors.initials: Y
authors.lastname: Miura
authors.forename: Katsuhiro
authors.initials: K
authors.lastname: Ichikawa
authors.forename: Takanori
authors.initials: T
authors.lastname: Hara
authors.forename: Shinji
authors.initials: S
authors.lastname: Niwa
authors.forename: Ichiro
authors.initials: I
authors.lastname: Fujimura
authors.forename: Shoichi
authors.initials: S
authors.lastname: Terakawa
mesh_terms: D006801:Humans; D008168:Lung / Q000000981:diagnostic imaging*; D019047:Phantoms, Imaging; D011829:Radiation Dosage; D013902:Radiography, Thoracic / Q000379:methods; D012680:Sensitivity and Specificity; D014057:Tomography, X-Ray Computed / Q000379:methods*