Spiral-helical Techniques – Biomedical Imaging Division, VT / WFU School of Biomedical Engineering and Sciences
http://www.bid.sbes.vt.edu
Biomedical Imaging Division, VT / WFU SBESSun, 27 Mar 2016 22:44:19 +0000en-UShourly1https://wordpress.org/?v=4.5.2Wang G, Vannier MW: Optimal pitch in spiral computed tomography. Medical Physics 24:1635-1639
http://www.bid.sbes.vt.edu/1997/10/wang-g-vannier-mw-optimal-pitch-in-spiral-computed-tomography-medical-physics-241635-1639/
http://www.bid.sbes.vt.edu/1997/10/wang-g-vannier-mw-optimal-pitch-in-spiral-computed-tomography-medical-physics-241635-1639/#respondWed, 01 Oct 1997 18:00:28 +0000http://localhost/wordpress/?p=430The focus of this paper is to analytically optimize spiral/helical computed tomography (CT) protocols based on a simplified imaging model. Spiral CT was approximately modeled as follows: Using the half-scan raw data interpolation method, the variance of the spiral CT slice sensitivity profile is equal to the sum of squared detector collimation divided by 12 and squared table increment divided by 24. Image noise variance is inversely proportional to tube current and detector collimation. The maximum continuous scanning time is inversely proportional to tube current. Slice thickness, image noise, and signal-to-noise ratio were, respectively, optimized for a given scanning coverage, consistently resulting in pitch of square root of 2. To avoid longitudinal aliasing, at least 2-3 transverse slices should be reconstructed per collimation. When the simplified spiral CT model is valid and a scanning range specified, 1.4 pitch is required for optimal image quality. The method can be applied to more accurate spiral CT models. Click here for full article….
]]>http://www.bid.sbes.vt.edu/1997/10/wang-g-vannier-mw-optimal-pitch-in-spiral-computed-tomography-medical-physics-241635-1639/feed/0Wang G, Vannier MW: Maximum volume coverage in spiral CT. Academic Radiology 3:423-428, 1996
http://www.bid.sbes.vt.edu/1996/05/wang-g-vannier-mw-maximum-volume-coverage-in-spiral-ct-academic-radiology-3423-428-1996/
http://www.bid.sbes.vt.edu/1996/05/wang-g-vannier-mw-maximum-volume-coverage-in-spiral-ct-academic-radiology-3423-428-1996/#respondWed, 01 May 1996 18:00:23 +0000http://localhost/wordpress/?p=414Rationale and Objectives. 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(2) Conclusion. 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. Click here for full article….
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