Title :
Noise in reconstructed images in tomography parallel, fan and cone beam projections
Author :
Hiriyannaiah, Harish P. ; Snyder, Wesley E. ; Bilbro, Griff L.
Author_Institution :
Center for Commun. & Signal Process., North Carolina State Univ., Raleigh, NC, USA
Abstract :
A principle source of noise in X-ray and emission computer tomography is at the detectors that measure the projection of the object. The noise can be approximated by additive, signal-independent white Gaussian statistics by ignoring the negligible effects of scattering and diffraction of the source beam. The back-projection filter that is used significantly alters power spectral density of the noise, such that the back-projected noise at each reconstructed point is no longer white. However, to effectively restore the reconstructed image using maximum a posteriori techniques via mean field annealing (MFA), a reasonable estimate of the autocorrelation of the back-projected noise is necessary. This work derives the autocorrelation and power spectra of the reconstructed noise for parallel, fan, and cone beam projections and also shows some preliminary results of MFA restorations
Keywords :
computerised tomography; noise; radioisotope scanning and imaging; X-ray tomography; autocorrelation spectra; back-projected noise autocorrelation; cone beam projection; diffraction; emission computer tomography; fan projection; maximum a posteriori techniques; mean field annealing; parallel projection; power spectral density; reconstructed images; scattering; signal-independent white Gaussian statistics; Autocorrelation; Gaussian noise; Image reconstruction; Image restoration; Noise measurement; Object detection; Tomography; X-ray detection; X-ray detectors; X-ray imaging;
Conference_Titel :
Computer-Based Medical Systems, 1990., Proceedings of Third Annual IEEE Symposium on
Conference_Location :
Chapel Hill, NC
Print_ISBN :
0-8186-9040-2
DOI :
10.1109/CBMSYS.1990.109382
