Low-dose CT screening for lung cancer with automatic exposure control: phantom study.
We conducted a study to determine optimal scan conditions for automatic exposure control (AEC) in computed tomography (CT) of low-dose chest screening in order to provide consistent image quality without increasing the collective dose. Using a chest CT phantom, we set CT-AEC scan conditions with a dose-reduction wedge (DR-Wedge) to the same radiation dose as those for low-tube current, fixed-scan conditions. Image quality was evaluated with the use of the standard deviation of the CT number, contrast-noise ratios (CNR), and receiver-operating characteristic (ROC) analysis. At the same radiation dose, in the scan conditions using CT-AEC with the DR-Wedge, the SD of the CT number of each slice position was stable. The CNR values were higher at the lung apex and lung base under CT-AEC with the DR-Wedge than under standard scan conditions (p < 0.0002). In addition, ROC analysis of blind evaluation by four radiologists and three technologists showed that the image quality was improved for the lung apex (p < 0.009), tracheal bifurcation (p < 0.038), and lung base (p < 0.022) in the scan conditions using CT-AEC with the DR-Wedge. We achieved improvement of image quality without increasing the collective dose by using CT-AEC with the DR-Wedge under low-dose scan conditions.
Gomi
Shiho
S
Department of Cancer Screening Technology and Development, National Cancer Center Research Center for Cancer Prevention and Screening, Tokyo, Japan. sgomi@ncc.go.jp
Muramatsu
Yoshihisa
Y
Tsukagoshi
Shinsuke
S
Suzuki
Masahiro
M
Kakinuma
Ryutaro
R
Tsuchiya
Ryosuke
R
Moriyama
Noriyuki
N
D001331:Automation; D055088:Early Detection of Cancer / Q000706:statistics & numerical data; D006801:Humans; D008175:Lung Neoplasms / Q000000981:diagnostic imaging* / Q000473:pathology; D019047:Phantoms, Imaging; D011482:Protective Devices; D011785:Quality Assurance, Health Care; D011829:Radiation Dosage; D011835:Radiation Protection; D014057:Tomography, X-Ray Computed / Q000295:instrumentation* / Q000379:methods
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