206 results about "X ray spectra" patented technology

A method of and a system for spectral correction in multi-energy computed tomography are provided to correct reconstructed images, including high-energy CT images and Z (effective atomic number) images, for spectral variations, which include time variations on a scanner due to HVPS drift and scanner to scanner variations due to the beamline component differences. The method uses a copper filter mounted on the detector array for tracking the spectral changes. The method comprises: generating copper ratios; computing working air tables; calculating scales and offsets; and correcting high-energy CT images and Z images using calculated scales and offsets. The method further includes an off-line calibration procedure to generate necessary parameters for the online correction.

Method of and system for adaptive scatter correction in the absence of scatter detectors in multi-energy computed tomography are provided, wherein input projection data acquired using at least two x-ray spectra for scanned objects may include a set of low energy projections and a set of high energy projections; wherein a low-pass filter of variable size is provided; the method comprises estimating the size of the low-pass filter; computing amounts of scatter; and correcting both sets of projections for scatter. The estimation of low-pass filter size comprises thresholding high energy projections into binary projections; filtering the binary projections; finding the maximum of the filtered binary projections; calculating the low-pass filter size from the found maximum. The computation of amounts of scatter comprises exponentiating input projections; low-pass filtering the exponentiated projections with the estimated filter size; computing the amounts of scatter from the filtered projections.

An X-ray spectrometer which uses at least one curved analyzing crystal and which provides improved wavelength resolution of characteristic X-rays used for analysis and improved ratio of characteristic X-rays to background intensity by using only effective diffractive regions of the analyzing crystal. X-ray blocking plates upstand from an end of a crystal support member supporting the analyzing crystal in the direction of angular dispersion of the crystal toward the inside of a Rowland circle. Incident X-rays going from the point X-ray source toward the crystal and X-rays diffracted by the crystal toward an X-ray detector are partially blocked by the X-ray blocking plates. The shielded regions vary according to the incident angle θ of the incident X-rays. Optimum or nearly optimum effective regions of the surface of the crystal can be used at all times.

This invention relates to an optically coupled digital radiography method and apparatus for simultaneously obtaining two distinct images of the same subject, each of which represents a different x-ray energy spectrum. The two images may be combined in various ways such that anatomical features may be separated from one another to provide a clearer view of those features or of underlying structures. The two different images are obtained using a pair of scintillators separated by an x-ray filter that attenuates part of the x-ray spectrum of an x-ray exposure such that the first and second scintillators receive a different energy spectrum of the same x-ray exposure. Alternatively, the two different images can be obtained without a filter and with two scintillators made of different fluorescing materials that react differently to the same x-ray exposure.

A method for performing x-ray absorption spectroscopy and an x-ray absorption spectrometer system to be used with a compact laboratory x-ray source to measure x-ray absorption of the element of interest in an object with both high spatial and high spectral resolution. The spectrometer system comprises a compact high brightness laboratory x-ray source, an optical train to focus the x-rays through an object to be examined, and a spectrometer comprising a single crystal analyzer (and, in some embodiments, also a mosaic crystal) to disperse the transmitted beam onto a spatially resolving x-ray detector. The high brightness / high flux x-ray source may have a take-off angle between 0 and 105 mrad. and be coupled to an optical train that collects and focuses the high flux x-rays to spots less than 500 micrometers, leading to high flux density. The coatings of the optical train may also act as a “low-pass” filter, allowing a predetermined bandwidth of x-rays to be observed at one time while excluding the higher harmonics.

An x-ray spectrometer system comprising an x-ray imaging system with at least one achromatic imaging x-ray optic and an x-ray detection system. The optical train of the imaging system is arranged so that its object focal plane partially overlaps an x-ray emitting volume of an object. An image of a portion of the object is formed with a predetermined image magnification at the x-ray detection system. The x-ray detection system has both high spatial and spectral resolution, and converts the detected x-rays to electronic signals. In some embodiments, the detector system may have a small aperture placed in the image plane, and use a silicon drift detector to collect x-rays passing through the aperture. In other embodiments, the detector system has an energy resolving pixel array x-ray detector. In other embodiments, wavelength dispersive elements may be used in either the optical train or the detector system.