Abstract: For correcting differential phase image data 52, differential phase image data 52 acquired with radiation at different energy levels is received, wherein the differential phase image data 52 comprises pixels 60, each pixel 60 having a phase gradient value 62a, 62b, 62c for each energy level. After that an energy dependent behavior of phase gradient values 62a, 62b, 62c of a pixel 60 is determined and a corrected phase gradient value 68 for the pixel 60 is determined from the phase gradient values 62a, 62b, 62c of the pixel 60 and a model for the energy dependence of the phase gradient values 62a, 62b, 62c.

Abstract: For correcting differential phase image data 52, differential phase image data 52 acquired with radiation at different energy levels is received, wherein the differential phase image data 52 comprises pixels 60, each pixel 60 having a phase gradient value 62a, 62b, 62c for each energy level. After that an energy dependent behavior of phase gradient values 62a, 62b, 62c of a pixel 60 is determined and a corrected phase gradient value 68 for the pixel 60 is determined from the phase gradient values 62a, 62b, 62c of the pixel 60 and a model for the energy dependence of the phase gradient values 62a, 62b, 62c.

Abstract: A method includes detecting radiation that traverses a material having a known spectral characteristic with a radiation sensitive detector pixel that outputs a signal indicative of the detected radiation and determining a mapping between the output signal and the spectral characteristic. The method further includes determining an energy of a photon detected by the radiation sensitive detector pixel based on a corresponding output of the radiation sensitive detector pixel and the mapping.

Abstract: An imaging system includes a radiation source (106, T1, T2, T3) that rotates about an examination region and emits radiation that traverses the examination region. The radiation source (106, T1, T2, T3) emits radiation having an energy spectrum that is selectively alternately switched between at least two different energy spectra during an imaging procedure. The system further includes an energy-resolving detector array (116, D1, D2, D3) that detects radiation traversing the examination region. The energy-resolving detector array (116, D1, D2, D3) resolves the detected radiation over at least two different energy ranges and produces energy-resolved output signals as a function of both emission energy spectrum and energy range. The system further includes a reconstructor (126) that performs a spectral reconstruction of the energy-resolved output signals. In another embodiment, the detector array (116) includes a photon-counting detector array (116).

Abstract: An apparatus includes a local minimum identifier (408) that identifies a local minimum between overlapping pulses in a signal, wherein the pulses have amplitudes that are indicative of the energy of successively detected photons from a multi-energetic radiation beam by a radiation sensitive detector, and a pulse pile-up error corrector (232) that corrects, based on the local minimum, for a pulse pile-up energy-discrimination error when energy-discriminating the pulses using at least two thresholds corresponding to different energy levels. This technique may reduce spectral error when counting photons at a high count rate.

Abstract: An imaging system including a radiation source (110) that emits poly-chromatic radiation that traverses an examination region and a detector (116) that detects radiation traversing the examination region and produces a signal indicative of the energy of a detected photon. The system further includes an energy discriminator (122) that energy resolves the signal based on a plurality of different energy thresholds, wherein at least two of the energy thresholds have values corresponding to at least two different K-edge energies of two different elements in a mixture disposed in the examination region. The system also includes a signal decomposer (132) that decomposes the energy-resolved signal into at least a multi K-edge component representing the at least two different K-edge energies. In one instance, a stoichiometric ratio of the two different elements in the contrast agent is known and substantially constant.

Abstract: The invention relates to a beam filter (10) that can particularly be used in spectral CT-applications for producing a desired intensity profile of a radiation beam without changing its spectral composition. In a preferred embodiment, the beam filter (10) comprises a stack of absorbing sheets (111) that are separated by wedge-shaped spaces (112) and focused to a radiation source (1). Furthermore, the absorbing sheets have a varying width in direct ion of the radiation. Different fractions of the radiation source (1) area are therefore masked by the beam filter (10) at different points (A, B) on a detector area (2). The absorbing sheets preferably comprise a material that is highly absorbing for the radiation to be filtered.

Abstract: An imaging system including a radiation source (110) that emits poly-chromatic radiation that traverses an examination region and a detector (116) that detects radiation traversing the examination region and produces a signal indicative of the energy of a detected photon. The system further includes an energy discriminator (122) that energy resolves the signal based on a plurality of different energy thresholds, wherein at least two of the energy thresholds have values corresponding to at least two different K-edge energies of two different elements in a mixture disposed in the examination region. The system also includes a signal decomposer (132) that decomposes the energy-resolved signal into at least a multi K-edge component representing the at least two different K-edge energies. In one instance, a stoichiometric ratio of the two different elements in the contrast agent is known and substantially constant.

Abstract: An imaging system includes a radiation source (106, T1, T2, T3) that rotates about an examination region and emits radiation that traverses the examination region. The radiation source (106, T1, T2, T3) emits radiation having an energy spectrum that is selectively alternately switched between at least two different energy spectra during an imaging procedure. The system further includes an energy-resolving detector array (116, D1, D2, D3) that detects radiation traversing the examination region. The energy-resolving detector array (116, D1, D2, D3) resolves the detected radiation over at least two different energy ranges and produces energy-resolved output signals as a function of both emission energy spectrum and energy range. The system further includes a reconstructor (126) that performs a spectral reconstruction of the energy-resolved output signals. In another embodiment, the detector array (116) includes a photon-counting detector array (116).

Abstract: A method includes detecting radiation that traverses a material having a known spectral characteristic with a radiation sensitive detector pixel that outputs a signal indicative of the detected radiation and determining a mapping between the output signal and the spectral characteristic. The method further includes determining an energy of a photon detected by the radiation sensitive detector pixel based on a corresponding output of the radiation sensitive detector pixel and the mapping.

Abstract: An apparatus includes a local minimum identifier (408) that identifies a local minimum between overlapping pulses in a signal, wherein the pulses have amplitudes that are indicative of the energy of successively detected photons from a multi-energetic radiation beam by a radiation sensitive detector, and a pulse pile-up error corrector (232) that corrects, based on the local minimum, for a pulse pile-up energy-discrimination error when energy-discriminating the pulses using at least two thresholds corresponding to different energy levels. This technique may reduce spectral error when counting photons at a high count rate.

Abstract: It is described a method and a CT system for measuring dual-energy X- ray attenuation data of an object. The CT system comprises a rotatable holder, an X-ray source comprising two different X-ray focus points, and an X-ray detection device comprising a plurality of detector elements exhibiting different spectral sensitivities. The method comprises the steps of (a) adjusting the X-ray source such that it emits X-rays originating a first focus point, (b) acquiring first attenuation data separately with first detector elements and with second detector elements, (c) moving the X-ray focus discretely to a second focus point, and (d) acquiring second attenuation data separately with both types of detector elements.

Abstract: A Computer Tomography system for examining an object is disclosed. The system comprises a first X-ray tube, a second X-ray tube, a first X-ray detection unit and a second X-ray detection unit. Preferably, the first X-ray detection unit is adapted to acquire a first data set by detecting radiation emitted by the first X-ray tube after passing through the object under examination, and the second X-ray detection unit is adapted to acquire a second data set by detecting radiation emitted by the second X-ray tube after being scattered by the object under examination. The system has particular application to the field of baggage inspection.

Abstract: According to an exemplary embodiment an imaging system (100) for examining an object under examination comprises a scanning unit, wherein the scanning unit comprises a radiation source (106, 108), and a detection unit (107, 109), wherein the scanning unit is adapted to emit a radiation beam (123), which radiation beam follows a linear movement of the object under examination such that a predetermined region of the object under examination is scanned while the object under examination moves.

Abstract: It is described a method and a CT system for measuring dual-energy X- ray attenuation data of an object. The CT system comprises a rotatable holder, an X-ray source comprising two different X-ray focus points, and an X-ray detection device comprising a plurality of detector elements exhibiting different spectral sensitivities. The method comprises the steps of (a) adjusting the X-ray source such that it emits X-rays originating a first focus point, (b) acquiring first attenuation data separately with first detector elements and with second detector elements, (c) moving the X-ray focus discretely to a second focus point, and (d) acquiring second attenuation data separately with both types of detector elements.

Abstract: The invention relates to a beam filter (10) that can particularly be used in spectral CT-applications for producing a desired intensity profile of a radiation beam without changing its spectral composition. In a preferred embodiment, the beam filter (10) comprises a stack of absorbing sheets (111) that are separated by wedge-shaped spaces (112) and focused to a radiation source (1). Furthermore, the absorbing sheets have a varying width in direct ion of the radiation. Different fractions of the radiation source (1) area are therefore masked by the beam filter (10) at different points (A, B) on a detector area (2). The absorbing sheets preferably comprise a material that is highly absorbing for the radiation to be filtered.

Abstract: A computer tomography apparatus (200) for examination of an object of interest (207), the computer tomography apparatus (200) comprising detecting elements (223) adapted to detect, as detecting signals, electromagnetic radiation scattered from an object of interest (207) in an energy-resolving manner, and a combination unit (225) adapted to combine detecting signals detected by different detecting elements (223) such as to reduce the amount of data to be processed for determining structural information concerning the object of interest (207).

Abstract: Method and apparatus are provided for combining information obtained from CT and Coherent Scatter Computed Tomography to better determine whether there are dangerous materials in the baggage or not. Hence, the attenuation coefficient and the diffraction pattern of the item of baggage are used to determine whether the baggage should be cleared.

Abstract: According to an embodiment of the present invention, a reconstruction scheme for a CSCT is provided which is capable of reconstructing data acquired just over a half turn, i.e. 180° plus fan angle. The reconstruction scheme may provide for an extension of the reconstruction towards smaller and larger q-regions as compared with a 360°-reconstruction, if the short scan reconstruction technique is applied to a full scan data set.

Abstract: Conventional CSCT may require a complex reconstruction involving a large number of calculations. According to an exemplary embodiment of the present invention, additional collimators are used in combination with energy revolving detectors, which may allow that a CSCT image may be reconstructed by a simple superposition of images obtained from different viewing angles in a direct tomography data acquisition scheme. Advantageously, a reconstruction may be avoided. Advantageously, this may allow for an improved image quality while reducing an amount of calculations required for generating the output image.