Impact of scattered radiation on spectral CT

Jens Wiegert; Klaus Jürgen Engel; Christoph Herrmann

doi:10.1117/12.813674

14 March 2009 Impact of scattered radiation on spectral CT

Jens Wiegert, Klaus Jürgen Engel, Christoph Herrmann

Proceedings Volume 7258, Medical Imaging 2009: Physics of Medical Imaging; 72583X (2009) https://doi.org/10.1117/12.813674
Event: SPIE Medical Imaging, 2009, Lake Buena Vista (Orlando Area), Florida, United States

Abstract

In "Spectral CT" based on energy-resolving photon-counting detectors (also "multi-energy CT") spectral information of transmitted X-radiation is measured in order to extract additional information about the material composition of the scanned object. Common practice is to decompose the attenuation line integrals into several components based on models of physical (e.g. photo/Compton/K-edge) or material properties (e.g. water/calcium). Scattered radiation causes a significant deterioration to the results, which are obtained with these models, as the measured spectrum in a specific detector element contains additional contributions which are not related to the attenuation in the respective line integral of the beam. In this paper the detrimental impact of scattered radiation in multi-energy CT is quantitatively analyzed by means of Monte-Carlo simulations. Large projection data sets of full rotational acquisitions are computed by combining noise-free analytical primary radiation with Monte-Carlo calculated scattered radiation of high statistical accuracy. The simulations show that, compared to the primary spectrum, the scatter spectrum is significantly shifted towards lower energies resulting in very high scatter-to-primary ratios for energies below 50keV. In the analysis of sinograms and reconstructed data using extended Alvarez-Macovsky decomposition into Photo-, Compton-, and K-edge images, it is revealed that scattered radiation causes significant inhomogeneity artifacts especially in the Photo image. Additionally "crosstalk" between Photo-, Compton- and K-edge images is found as K-edge structures appear in the other images and vice versa. Quantitatively it is found that due to scatter the reconstructed concentration of the K-edge material is up to 23 % smaller than its correct value.

Citation Download Citation

Jens Wiegert, Klaus Jürgen Engel, and Christoph Herrmann "Impact of scattered radiation on spectral CT", Proc. SPIE 7258, Medical Imaging 2009: Physics of Medical Imaging, 72583X (14 March 2009); https://doi.org/10.1117/12.813674

ACCESS THE FULL ARTICLE

INSTITUTIONAL
Select your institution to access the SPIE Digital Library.

SELECT YOUR INSTITUTION

PERSONAL
Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.

PERSONAL SIGN IN

No SPIE Account? Create one

PURCHASE THIS CONTENT

SUBSCRIBE TO DIGITAL LIBRARY

50 downloads per 1-year subscription

Members: $195

Non-members: $335 ADD TO CART

25 downloads per 1 - year subscription

Members: $145

Non-members: $250 ADD TO CART

PURCHASE SINGLE ARTICLE

Includes PDF, HTML & Video, when available