Maximum volume coverage in spiral computed tomography scanning.
OBJECTIVE
Given a slice thickness and an image noise level, volume coverage in spiral computed tomography (CT) scanning was maximized with respect to detector collimation and table increment.


METHODS
The maximization was analytically performed on the basis of the following relationships: (1) With the half-scan interpolation method, the slice sensitivity profile (SSP) in spiral CT scanning is the convolution of a rectangular detector response function (the width is equal to the detector collimation) and a triangular table motion function (the base is equal to the table increment); (2) the SSP variance is equal to the sum of squared detector collimation divided by 12 and squared table increment divided by 24; (3) the image noise variance is inversely proportional to tube current and detector collimation; and (4) the maximum continuous scanning time is inversely proportional to tube current.


RESULTS
Given a limited tube heat capability, a slice thickness, and an image noise level, we proved that the maximum volume coverage is reached with a pitch of square root of 2.


CONCLUSIONS
With a heat-limited tube and for a specified image quality in terms of slice thickness and image noise, a pitch of 1.4 should be used for maximum volume coverage in spiral CT scanning.
Wang
G
G
Mallinckrodt Institute of Radiology, Washington University School of Medicine, St. Louis, MO 63110, USA.
Vannier
M W
MW
D006801:Humans; D013679:Technology, Radiologic; D014057:Tomography, X-Ray Computed / Q000379:methods*