Phase-space formulation for phase-contrast x-ray imaging.
Phase-space formulation based on the Wigner distribution has been presented for analyzing phase-contrast image formation. Based on the statistical nature and affine canonical covariance of Wigner distributions in the phase space, we show that the partial coherence effects of incident x-ray wave field on image intensity are simply accounted for by a multiplication factor, which is the reduced complex degree of coherence of the incident x-ray wave field. We show especially that with the undulator sources one cannot obtain the phase-contrast intensity by summing over the contributions from all electron positions, since the van Cittert-Zernike theorem fails in general for undulators. We derive a comprehensive formula that quantifies the effects of partial spatial coherence, polychromatic spectrum, body attenuation, imaging-detector resolution, and radiation dose on phase-contrast visibility in clinical imaging. The results of our computer modeling and simulations show how the formula can provide design guidelines and optimal parameters for clinical x-ray phase-contrast imaging systems.
Wu
Xizeng
X
Department of Radiology, University of Alabama at Birmingham, Birmingham, Alabama 35233, USA. xwu@uabmc.edu
Liu
Hong
H
D000465:Algorithms; D003198:Computer Simulation; D008858:Microscopy, Phase-Contrast / Q000379:methods*; D008962:Models, Theoretical; D011856:Radiographic Image Enhancement / Q000379:methods*; D011857:Radiographic Image Interpretation, Computer-Assisted / Q000379:methods*; D011859:Radiography / Q000379:methods*; D012031:Refractometry / Q000379:methods*