Biological Imaging by X-ray Phase Tomography Using Diffraction-Enhanced Imaging

Abstract

A feasibility test of phase tomography using diffraction-enhanced imaging (DEI) was performed with biological tissues consisting of not only soft tissues but also cartilages and bones. Reconstructed three-dimensional images indicated that phase tomography using DEI has an advantage from a biological viewpoint over phase tomography using a crystal X-ray interferometer, which cannot be applied to samples involving marked refractive index changes at boundaries between soft tissues and bones or cartilages.

General reconstruction formulas for analyzer-based computed tomography

“…This imaging geometry was also used in Ref. 12, but no specific consequences of this geometry for the stability of CT reconstruction were mentioned there.…”

Innovative radiographic system to improve the sharpness of radiographs: could a phase-shift effect contribute to improved image-quality for plain computed radiographs for general use?

“…Phase contrast also exists, which takes place after X-rays penetrate the object and theoretically allows much higher contrast and spatial resolution than with absorption imaging, 1 without excessive doses of radiation. Potential applications of in-line phase contrast to X-ray imaging were initially tested during the 1990s, mostly using synchrotron radiation monochromized by a crystal, which provides strong, coherent X-rays that are suitable for study with phase-contrast imaging and has been shown to be useful for imaging microscopic and/or low-contrast objects that cannot be imaged using standard X-ray techniques, [2][3][4][5][6][7][8][9][10][11] such as blood vessels of rats in vivo without contrast agents. 12 Through experiments with synchrotron radiation, not only pure phasecontrast imaging but also an edge-enhancement effect superimposed on absorption contrast due to the diffraction of X-rays, in which changes in the direction of propagation of X-rays after they penetrate through an object are extracted to enhance X-ray images by means of the Bragg refl ection, has been observed.…”

“…12 Through experiments with synchrotron radiation, not only pure phasecontrast imaging but also an edge-enhancement effect superimposed on absorption contrast due to the diffraction of X-rays, in which changes in the direction of propagation of X-rays after they penetrate through an object are extracted to enhance X-ray images by means of the Bragg refl ection, has been observed. 7,10,11,13 Also called "diffraction-enhanced imaging," this technique has been expected to sharpen X-ray images and thus potentially improve the precision of radiography. 13 However, synchrotron radiation is only possible using extremely large, specialized equipment and the X-ray beam provided is very narrow; hence, this technique has not been considered clinically applicable.…”

Development of diffraction enhanced imaging at beamline BL07 at the SAGA Light Source and its application

“…The cross section of a phase shift is about 1000 times larger than an absorption cross section, which enables us to observe the structure of soft materials such as bio-materials or polymers. Compared to several other phase imaging methods that use a crystal interferometer [1-3], propagation-based phase imaging [4], and X-ray Talbot interferometry [5,6], diffraction enhanced imaging (DEI) has advantages such as a wide dynamic range of the material density and a simple experimental arrangement [7][8][9]. In the DEI method, refraction angles of X-rays penetrating materials are analyzed by a crystal analyzer.…”