Abstract:
A method for phase contrast imaging comprises: illuminating an object by terahertz radiation such that the terahertz radiation interacts with the object; illuminating a diffraction grating by the terahertz radiation that has interacted with the object; translating the diffraction grating along the direction of the grating wave vector, to measure, for each of different grating positions, an intensity distribution of the terahertz radiation that has interacted with the object and with the grating in a diffraction field; and retrieving a phase contrast image of the object from the intensity distributions. An apparatus for phase contrast imaging is also provided.
Abstract:
A method for phase contrast imaging comprises: illuminating an object by terahertz radiation such that the terahertz radiation interacts with the object; illuminating a diffraction grating by the terahertz radiation that has interacted with the object; translating the diffraction grating along the direction of the grating wave vector, to measure, for each of different grating positions, an intensity distribution of the terahertz radiation that has interacted with the object and with the grating in a diffraction field; and retrieving a phase contrast image of the object from the intensity distributions. An apparatus for phase contrast imaging comprises: a terahertz radiation emitter for generating terahertz radiation, which illuminates an object to interact with the object; a diffraction grating, which is illuminated by the terahertz radiation that has interacted with the object; a terahertz radiation detector for measuring, for each of different grating positions, an intensity distribution of the terahertz radiation that has interacted with the object and with the grating in a diffraction field; and a data collecting and processing system for retrieving a phase contrast image of the object from the intensity distributions.
Abstract:
A method and apparatus for CT image reconstruction may include selecting, by a unit, projection data of the same height on a curve having a curvature approximate to that of the scanning circular orbit, implementing, by a unit, a weighting processing on the selected projection data, filtering, by a unit, the weighting processed projection data along a horizontal direction, implementing, by a unit, three-dimensional back projection on the filtered projection data along the direction of ray. The method and apparatus can effectively eliminate cone beam artifact under a large cone angle.
Abstract:
A method and apparatus for CT image reconstruction may include selecting, by a unit, projection data of the same height on a curve having a curvature approximate to that of the scanning circular orbit, implementing, by a unit, a weighting processing on the selected projection data, filtering, by a unit, the weighting processed projection data along a horizontal direction, implementing, by a unit, three-dimensional back projection on the filtered projection data along the direction of ray. The method and apparatus can effectively eliminate cone beam artifact under a large cone angle.
Abstract:
An X-ray imaging system comprising: an X-ray source, a source grating, a fixed grating module and an X-ray detector, which are successively positioned in the propagation direction of X-ray; an object to be detected is positioned between the source grating and the fixed gating module; said source grating can perform stepping movement in a direction perpendicular to the optical path and grating stripes; wherein the system further comprises a computer workstation for controlling said X-ray source, source grating and X-ray detector so as to perform the following processes: the source grating performs stepping movement in at least one period thereof; at each stepping step, the X-ray source emits X-ray to the object to be detected, and the detector receives the X-ray at the same time; wherein after at least one period of stepping and data acquisition, the light intensity of X-ray at each pixel point on the detector is represented as a light intensity curve; the light intensity curve at each pixel point on the detector is compared with a light intensity curve in the absence of the object to be detected, a pixel value of each pixel point is calculated from change in said light intensity curve; an image of the detected object is reconstructed according to the calculated pixel value.
Abstract:
An X-ray imaging system comprising: an X-ray source, a source grating, a fixed grating module and an X-ray detector, which are successively positioned in the propagation direction of X-ray; an object to be detected is positioned between the source grating and the fixed gating module; said source grating can perform stepping movement in a direction perpendicular to the optical path and grating stripes; wherein the system further comprises a computer workstation for controlling said X-ray source, source grating and X-ray detector so as to perform the following processes: the source grating performs stepping movement in at least one period thereof; at each stepping step, the X-ray source emits X-ray to the object to be detected, and the detector receives the X-ray at the same time; wherein after at least one period of stepping and data acquisition, the light intensity of X-ray at each pixel point on the detector is represented as a light intensity curve; the light intensity curve at each pixel point on the detector is compared with a light intensity curve in the absence of the object to be detected, a pixel value of each pixel point is calculated from change in said light intensity curve; an image of the detected object is reconstructed according to the calculated pixel value.
Abstract:
An x-ray imaging technology, performing an x-ray dark-field CT imaging of an examined object using an imaging system which comprises an x-ray source, two absorbing gratings G1 and G2, an x-ray detector, a controller and a data processing unit, comprising the steps of: emitting x-rays to the examined object; enabling one of the two absorbing gratings G1 and G2 to perform phase stepping motion within at least one period range thereof; where in each phase stepping step, the detector receives the x-ray and converts it into an electric signal; wherein through the phase stepping of at least one period, the x-ray intensity at each pixel point on the detector is represented as an intensity curve; calculating a second moment of scattering angle distribution for each pixel, based on a contrast of the intensity curve at each pixel point on the detector and an intensity curve without presence of the examined object; taking images of the object at various angles, then obtaining an image with scattering information of the object in accordance with a CT reconstruction algorithm.
Abstract:
An x-ray imaging technology, performing an x-ray dark-field CT imaging of an examined object using an imaging system which comprises an x-ray source, two absorbing gratings G1 and G2, an x-ray detector, a controller and a data processing unit, comprising the steps of: emitting x-rays to the examined object; enabling one of the two absorbing gratings G1 and G2 to perform phase stepping motion within at least one period range thereof; where in each phase stepping step, the detector receives the x-ray and converts it into an electric signal; wherein through the phase stepping of at least one period, the x-ray intensity at each pixel point on the detector is represented as an intensity curve; calculating a second moment of scattering angle distribution for each pixel, based on a contrast of the intensity curve at each pixel point on the detector and an intensity curve without presence of the examined object; taking images of the object at various angles, then obtaining an image with scattering information of the object in accordance with a CT reconstruction algorithm.