Application of subsecond rotation scan to helical CT for lung cancer screening.
OBJECTIVE
To clarify whether the benefit of a reduced effective scan width obtained using a smaller pitch outweighs the disadvantage of increased noise in the application of a subsecond helical CT to mass screenings for lung cancer.


METHODS
Twenty-two helical CT scans of the lung were obtained in 11 healthy subjects using the following parameters: 1) scan 1 was performed at 120 kVp, 50 mA, 10-mm collimation, 1-second/rotation, helical pitch of 2.0; and 2) scan 2 was performed at 120 kVp, 50 mA, 10-mm collimation, 0.75-second/rotation, helical pitch of 1.5. Computer-generated nodules measuring 10 mm and 6 mm in diameter showing ground-glass opacity were superimposed on these images. The detectability of each nodule was evaluated by six blinded readers using ROC analysis.


RESULTS
Detectability of the 6-mm nodules was significantly higher in scan 2 than in scan 1. Detectability of the 10-mm nodules was not significantly different between scans 1 and 2.


CONCLUSIONS
The use of a smaller pitch by employing a subsecond rotation scan in a helical CT for lung cancer screenings improves the detection of small lesions without increasing either the scanning time or radiation dose.
Mori
Yoshine
Y
Department of Radiology, Nagoya University Graduate School of Medicine, Japan. yoshine@jg7.so-net.ne.jp
Itoh
Shigeki
S
Ikeda
Mitsuru
M
Sawaki
Akiko
A
Suzuki
Koujiro
K
Iwano
Shingo
S
Satake
Hiroko
H
Arahata
Shoji
S
Ota
Toyohiro
T
Ishigaki
Takeo
T
D000328:Adult; D005260:Female; D006801:Humans; D007564:Japan; D008175:Lung Neoplasms / Q000000981:diagnostic imaging*; D008297:Male; D008403:Mass Screening; D008875:Middle Aged; D019047:Phantoms, Imaging; D036542:Tomography, Spiral Computed / Q000379:methods*