Koninklijke Philips Corporation N.v.

Koninklijke Philips Electrions N.v.

Jens-Peter Schlomka

Roland Proksa

Geoffrey Harding

Ewald Roessl

Thomas Koehler

Michael Grass

Gerhard Martens

Peter Forthmann

Naor Wainer

Axel Thran

Udo Van Stevendaal

Jörg Sabczynski

Jörn Borgert

Amir Livne

Tuvia Liran

Michael Wilhelm Paul Dargatz

Aviv Marks

Bernd Schreiber

Udo Van Steven-Daal

Michael Graβ

For correcting differential phase image data, differential phase image dataacquired with radiation at different energy levels is received, wherein the differential phase image datacomprises pixels, each pixelhaving a phase gradient valuefor each energy level. After that an energy dependent behavior of phase gradient valuesof a pixelis determined and a corrected phase gradient valuefor the pixelis determined from the phase gradient valuesof the pixeland a model for the energy dependence of the phase gradient values

Differential phase contrast imaging with energy sensitive detection

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.

Spectral detector calibration

An imaging system includes a radiation source (, T, T, T) that rotates about an examination region and emits radiation that traverses the examination region. The radiation source (, T, T, T) 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 (, D, D, D) that detects radiation traversing the examination region. The energy-resolving detector array (, D, D, D) 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 () that performs a spectral reconstruction of the energy-resolved output signals. In another embodiment, the detector array () includes a photon-counting detector array ().

Spectral CT

An apparatus includes a local minimum identifier () 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 () 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.

Digital pulse processing for multi-spectral photon counting readout circuits

An imaging system including a radiation source () that emits poly-chromatic radiation that traverses an examination region and a detector () 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 () 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 () 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.

K-edge imaging

The invention relates to a beam filter () 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 () comprises a stack of absorbing sheets () that are separated by wedge-shaped spaces () and focused to a radiation source (). Furthermore, the absorbing sheets have a varying width in direct ion of the radiation. Different fractions of the radiation source () area are therefore masked by the beam filter () at different points (A, B) on a detector area (). The absorbing sheets preferably comprise a material that is highly absorbing for the radiation to be filtered.

Beam filter, particularly for x-rays

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. Thereby the two focus points are spatially separated from each such that a first beam path originating from the first focus point penetrates a certain voxel within the object and impinges on a first detector element and a second beam path originating from the second X-ray focus point penetrates the same voxel and impinges on a second detector element.

Effective dual-energy x-ray attenuation measurement

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.

Coherent-scatter computer tomograph

A computer tomography apparatus for examination of an object of interest includes detecting elements adapted to detect electromagnetic radiation scattered from the object of interest in an energy-resolving manner. A combination unit is adapted to combine signals detected by different detecting elements such as to reduce the amount of data to be processed for determining structural information concerning the object of interest.

Computer tomography apparatus

In CSCT, by using a fan-shaped primary beam, combined with a 2D detector, single-slice transmission tomography and scatter tomography can be measured simultaneously. In such a System blurred scatter functions are measured unless a monochromatic source of radiation is used. According to the present invention, an energy resolving 1D or 2D detector System is proposed, which, in combination with a tomographic reconstruction, provides a good spectral resolution, even with a polychromatic primary beam. Furthermore, according to an aspect of the present invention, only one energy resolving detector-line is required to achieve the fall spectrum. Advantageous applications of the system and method according to the present invention are in medical imaging and material analysis, such as baggage inspection.

Fan-beam coherent-scatter computer tomography

The invention describes a method of generating metabolic images of an investigation region () of a body () by irradiating an X-ray fluorescence marker in that region and detecting the resulting X-ray fluorescence with a fluorescence detector (). A fan beam () is used as a source of primary X-radiation, thus allowing the scanning of a whole body slice () in one step. The fluorescence image may be directly measured, e.g. by mapping voxels () of the investigation region onto pixels () of the detector () with the help of a pinhole collimator (), or it may be reconstructed by procedures of computed tomography. Moreover, a morphological image may be generated by simultaneously recording X-ray transmission through the body ().

Method and imaging system for imaging the spatial distribution of an x-ray fluorescence marker

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.

Automatic material discrimination by using computer tomography

Due to the provision of slit collimators an intensity of a fan beam is reduced significantly such that expensive high power x-ray tubes have to be used. According to an exemplary embodiment of the present invention, a high power tube may be used with a very long focus in combination with a focusing collimator. The tube can be a cheap fixed anode tube still with a high power of, for example, 15 kW due to the large focus. The collimator may ensure that the resolution of the reconstructed scatter function is not degraded. The illuminated slice thickness is increased which may allow for an isotropic spatial resolution.

Focused coherent-scatter computer tomography

The invention relates to a computed tomography apparatus (CT apparatus) for imaging by means of radiation having traversed an object to be examined (that is, directly transmitted radiation), as well as by means of radiation scattered by the object to be examined, which apparatus includes a radiation source (S), a detector arrangement () and a device whereby the radiation () having traversed the object to be examined can be blocked at least to an extent that the intensity incident on the detector arrangement () does not substantially exceed the intensity of radiation () scattered by the object () to be examined and incident on the detector arrangement (). The invention enables the detection of scattered radiation (CSCT mode) which is not affected by crosstalk from the transmitted radiation, even when the detector arrangement does not satisfy severe requirements as regards crosstalk properties and/or is configured as a single-row detector arrangement.

Computed tomography apparatus

In CSCT, an exact reconstruction of a scattering function for each voxel is not known for polychromatic primary radiation. According to an exemplary embodiment of the present invention, a beam hardening compensation is performed prior to reconstruction allowing to perform a quasi-exact reconstruction on the basis of the primary radiation mean attenuation values are determined, from which an equivalent water thickness is derived. From the equivalent water thickness an energy shift is calculated, which is used to correct the initial mean energy of the scatter radiation. Furthermore, a CT reconstruction may be performed prior to a CSCT reconstruction allowing for a beam-hardening correction. Advantageously, this may allow for an improved image quality and an improved resolution of the scatter function.

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Hamburg, Germany

Jens-Peter Schlomka