title: Effect of x-ray energy dispersion in digital subtraction imaging at the iodine K-edge--a Monte Carlo study.
abstract: The effect of the energy dispersion of a quasi-monochromatic x-ray beam on the performance of a dual-energy x-ray imaging system is studied by means of Monte Carlo simulations using MCNPX (Monte Carlo N-Particle eXtended) version 2.6.0. In particular, the case of subtraction imaging at the iodine K-edge, suitable for angiographic imaging application, is investigated. The average energies of the two beams bracketing the iodine K-edge are set to the values of 31.2 and 35.6 keV corresponding to the ones obtained with a compact source based on a conventional x-ray tube and a mosaic crystal monochromator. The energy dispersion of the two beams is varied between 0 and 10 keV of full width at half-maximum (FWHM). The signal and signal-to-noise ratio produced in the simulated images by iodine-filled cavities (simulating patient vessels) drilled in a PMMA phantom are studied as a function of the x-ray energy dispersion. The obtained results show that, for the considered energy separation of 4.4 keV, no dramatic deterioration of the image quality is observed with increasing x-ray energy dispersion up to a FWHM of about 2.35 keV. The case of different beam energies is also investigated by means of fast simulations of the phantom absorption.
authors.affiliation: Dipartimento di Fisica Sperimentale dell'Università di Torino and INFN, Torino, Italy. prino@to.infn.it
authors.forename: F
authors.initials: F
authors.lastname: Prino
authors.forename: C
authors.initials: C
authors.lastname: Ceballos
authors.forename: A
authors.initials: A
authors.lastname: Cabal
authors.forename: A
authors.initials: A
authors.lastname: Sarnelli
authors.forename: M
authors.initials: M
authors.lastname: Gambaccini
authors.forename: L
authors.initials: L
authors.lastname: Ramello
mesh_terms: D015901:Angiography, Digital Subtraction / Q000379:methods*; D003198:Computer Simulation; D004583:Electrons; D006801:Humans; D007455:Iodine / Q000737:chemistry*; D009010:Monte Carlo Method; D019047:Phantoms, Imaging; D017785:Photons; D014965:X-Rays
chemical_list: D007455:Iodine