Phase Contrast Imaging
- Sincrotrone Trieste and INFN Trieste (Italy)
All standard (medical) x-ray imaging technologies, rely primarily on the amplitude properties of the incident radiation, and do not depend on its phase. This is unchanged since the discovery by Roentgen that the intensity of an x-ray beam, as measured by the exposure on a film, was related to the relative transmission properties of an object. However, recently various imaging techniques have emerged which depend on the phase of the x-rays as well as the amplitude. Phase becomes important when the beam is coherent and the imaging system is sensitive to interference phenomena. Significant new advances have been made in coherent optic theory and techniques, which now promise phase information in medical imaging. The development of perfect crystal optics and the increasing availability of synchrotron radiation facilities have contributed to a significant increase in the application of phase based imaging in materials and life sciences. Unique source characteristics such as high intensity, monochromaticity, coherence and high collimating provide an ideal source for advanced imaging. Phase contrast imaging has been applied in both projection and computed tomography modes, and recent applications have been made in the field of medical imaging. Due to the underlying principle of X-ray detection conventional image receptors register only intensities of wave fields and not their phases. During the last decade basically five different methods were developed that translate the phase information into intensity variations. These methods are based on measuring the phase shift {phi} directly (using interference phenomena), the gradient {nabla}{sub {phi}}, or the Laplacian {nabla}{sup 2}{phi}. All three methods can be applied to polychromatic X-ray sources keeping in mind that the native source is synchrotron radiation, featuring monochromatic and reasonable coherent X-ray beams. Due to the vast difference in the coefficients that are driven absorption and phase effects (factor 1,000-10,000 in the energy range suitable for medical imaging) phase based imaging techniques are inherently extremely sensitive.
- OSTI ID:
- 21254895
- Journal Information:
- AIP Conference Proceedings, Vol. 1077, Issue 1; Conference: Advanced summer school on physics 2008: Frontiers in contemporary physics, Mexico City (Mexico), 7-11 Jul 2008; Other Information: DOI: 10.1063/1.3040252; (c) 2008 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); ISSN 0094-243X
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
COSMOLOGY AND ASTRONOMY
99 GENERAL AND MISCELLANEOUS//MATHEMATICS, COMPUTING, AND INFORMATION SCIENCE
ABSORPTION
BINARY STARS
COMPUTERIZED TOMOGRAPHY
COSMIC X-RAY SOURCES
CRYSTALS
FILMS
INTERFERENCE
LAPLACIAN
MONOCHROMATIC RADIATION
OPTICS
PHASE SHIFT
RECEPTORS
SYNCHROTRON RADIATION
X RADIATION
X-RAY DETECTION