Computed tomography of x-ray index of refraction using the diffraction enhanced imaging method.

Diffraction enhanced imaging (DEI) is a new, synchrotron-based, x-ray radiography method that uses monochromatic, fan-shaped beams, with an analyser crystal positioned between the subject and the detector. The analyser allows the detection of only those x-rays transmitted by the subject that fall into the acceptance angle (central part of the rocking curve) of the monochromator/analyser system. As shown by Chapman et al, in addition to the x-ray attenuation, the method provides information on the out-of-plane angular deviation of x-rays. New images result in which the image contrast depends on the x-ray index of refraction and on the yield of small-angle scattering, respectively. We implemented DEI in the tomography mode at the National Synchrotron Light Source using 22 keV x-rays, and imaged a cylindrical acrylic phantom that included oil-filled, slanted channels. The resulting 'refraction CT image' shows the pure image of the out-of-plane gradient of the x-ray index of refraction. No image artefacts were present, indicating that the CT projection data were a consistent set. The 'refraction CT image' signal is linear with the gradient of the refractive index, and its value is equal to that expected. The method, at the energy used or higher, has the potential for use in clinical radiography and in industry.

[1]  André Guinier,et al.  X-ray Crystallography. (Book Reviews: X-Ray Diffraction in Crystals, Imperfect Crystals, and Amorphous Bodies) , 1963 .

[2]  B. Batterman,et al.  Dynamical Diffraction of X Rays by Perfect Crystals , 1964 .

[3]  Azriel Rosenfeld,et al.  Digital Picture Processing , 1976 .

[4]  Jerome B. Hastings,et al.  Computed tomography with monochromatic X rays from the National Synchrotron Light Source , 1991 .

[5]  M. E. Alferieff,et al.  Refraction contrast in X-ray introscopy , 1991 .

[6]  V. N. Ingal,et al.  X-ray plane-wave topography observation of the phase contrast from a non-crystalline object , 1995 .

[7]  S. Wilkins,et al.  Phase-contrast imaging of weakly absorbing materials using hard X-rays , 1995, Nature.

[8]  F. Arfelli,et al.  Mammography imaging studies using a Laue crystal analyzer , 1996 .

[9]  D. Mangra,et al.  Passive vibration damping of the APS machine components , 1996 .

[10]  D N Slatkin,et al.  Single-and dual-energy CT with monochromatic synchrotron x-rays. , 1997, Physics in medicine and biology.

[11]  E. Pisano,et al.  Diffraction enhanced x-ray imaging. , 1997, Physics in medicine and biology.

[12]  E Castelli,et al.  Low-dose phase contrast x-ray medical imaging. , 1998, Physics in medicine and biology.

[13]  Michael Hart,et al.  X-ray Optics for Synchrotron Radiation; Perfect Crystals, Mirrors and Multilayers , 1998 .

[14]  E Pisano,et al.  Medical applications of diffraction enhanced imaging. , 1998, Breast disease.

[15]  Y. Kohmura,et al.  Refraction-enhanced x-ray imaging of mouse lung using synchrotron radiation source. , 1999, Medical physics.

[16]  Atsushi Momose,et al.  Applications of phase-contrast x-ray imaging to medicine using an x-ray interferometer , 1999, Optics & Photonics.

[17]  P. Spanne,et al.  In-line holography and phase-contrast microtomography with high energy x-rays. , 1999, Physics in medicine and biology.

[18]  P. Spanne,et al.  Instrumentation of the ESRF medical imaging facility , 1999 .

[19]  William Thomlinson,et al.  Implementation of diffraction-enhanced imaging experiments: at the NSLS and APS , 2000 .