Monte Carlo Simulation for Polychromatic X-ray Fluorescence Computed Tomography with Sheet-Beam Geometry

摘要

X-ray fluorescence computed tomography based on sheet-beam can save a hugeamount of time to obtain a whole set of projections using synchrotron. However,it is clearly unpractical for most biomedical research laboratories. In thispaper, polychromatic X-ray fluorescence computed tomography with sheet-beamgeometry is tested by Monte Carlo simulation. First, two phantoms (A and B)filled with PMMA are used to simulate imaging process through GEANT 4. PhantomA contains several GNP-loaded regions with the same size (10 mm) in height anddiameter but different Au weight concentration ranging from 0.3% to 1.8%.Phantom B contains twelve GNP-loaded regions with the same Au weightconcentration (1.6%) but different diameter ranging from 1mm to 9mm. Second,discretized presentation of imaging model is established to reconstruct moreaccurate XFCT images. Third, XFCT images of phantom A and B are reconstructedby fliter backprojection (FBP) and maximum likelihood expectation maximization(MLEM) with and without correction, respectively. Contrast to noise ratio (CNR)is calculated to evaluate all the reconstructed images. Our results show thatit is feasible for sheet-beam XFCT system based on polychromatic X-ray sourceand the discretized imaging model can be used to reconstruct more accurateimages.