Share Email Print
cover

Proceedings Paper

Correction of cross-scatter in next generation dual source CT (DSCT) scanners
Author(s): H. Bruder; K. Stierstorfer; M. Petersilka; C. Wiegand; C. Suess; T. Flohr
Format Member Price Non-Member Price
PDF $14.40 $18.00
cover GOOD NEWS! Your organization subscribes to the SPIE Digital Library. You may be able to download this paper for free. Check Access

Paper Abstract

In dual source CT (DSCT) with two X-ray sources and two data measurement systems mounted on a CT gantry with a mechanical offset of 90 deg, cross scatter radiation, (essentially 90 deg Compton scatter) is added to the detector signals. In current DSCT scanners the cross scatter correction is model based: the idea is to describe the scattering surface in terms of its tangents. The positions of these tangent lines are used to characterize the shape of the scattering object. For future DSCT scanners with larger axial X-ray beams, the model based correction will not perfectly remove the scatter signal in certain clinical situations: for obese patients scatter artifacts in cardiac dual source scan modes might occur. These shortcomings can be circumvented by utilizing the non-diagnostic time windows in cardiac scan modes to detect cross scatter online. The X-ray generators of both systems have to be switched on and off alternating. If one X-ray source is switched off, cross scatter deposited in the respective other detector can be recorded and processed, to be used for efficient cross scatter correction. The procedure will be demonstrated for cardiac step&shoot as well as for spiral acquisitions. Full rotation reconstructions are less sensitive to cross scatter radiation; hence in non-cardiac case the model-based approach is sufficient. Based on measurements of physical and anthropomorphic phantoms we present image data for DSCT systems with various collimator openings demonstrating the efficacy of the proposed method. In addition, a thorough analysis of contrast-to-noise ratio (CNR) shows, that even for a X-ray beam corresponding to a 64x0.6 mm collimation, the maximum loss of CNR due to cross scatter is only about 7% in case of obese patients.

Paper Details

Date Published: 25 March 2008
PDF: 10 pages
Proc. SPIE 6913, Medical Imaging 2008: Physics of Medical Imaging, 69131W (25 March 2008); doi: 10.1117/12.768471
Show Author Affiliations
H. Bruder, Siemens AG (Germany)
K. Stierstorfer, Siemens AG (Germany)
M. Petersilka, Siemens AG (Germany)
C. Wiegand, Siemens AG (Germany)
C. Suess, Siemens AG (Germany)
T. Flohr, Siemens AG (Germany)


Published in SPIE Proceedings Vol. 6913:
Medical Imaging 2008: Physics of Medical Imaging
Jiang Hsieh; Ehsan Samei, Editor(s)

© SPIE. Terms of Use
Back to Top