Low-contrast resolution in volumetric x-ray CT--analytical comparison between conventional and spiral CT.
Spiral/helical computed tomography (CT) was introduced to scan an anatomical volume in a single breath-hold for better temporal resolution as compared to conventional CT. Recently, it was established that given an x-ray dose, spiral CT also allows better longitudinal high-contrast resolution due to retrospective reconstruction. In spiral CT, full scan with interpolation (FI) and half-scan with interpolation (HI) are limited by the degraded slice sensitivity profile and increased image noise, respectively. We combined these two interpolation methods for a desirable balance. This new interpolation method, FI + HI, was shown to produce 4% lower image noise standard deviation than conventional CT, without loss of longitudinal bandwidth according to one-tenth-cutoff and mean-square-root measures. The analytic model of image noise was validated in a water phantom experiment. Our findings suggest the superiority of spiral CT over conventional CT in terms of both low-contrast resolution and high-contrast resolution.
Wang
G
G
Department of Radiology, University of Iowa, Iowa City 52242, USA.
Vannier
M W
MW
D055592:Biophysical Phenomena; D001703:Biophysics; D005069:Evaluation Studies as Topic; D006801:Humans; D019047:Phantoms, Imaging; D011857:Radiographic Image Interpretation, Computer-Assisted; D015203:Reproducibility of Results; D013679:Technology, Radiologic; D014057:Tomography, X-Ray Computed / Q000379:methods* / Q000706:statistics & numerical data