Koninklijke Philips Corporation N.v.

U.S. Philips Corporation

Jan Timmer

Jantje E Wilting

Robert Johannes Frederik Homan

Pieter Maria Mielekamp

Peter George Van De Haar

Michael Grass

Roland Proksa

Holger Schmitt

Drazenko Babic

Hannes Nickisch

Nicolaas Jan Noordhoek

Willem P Van Der Brug

Petrus N Vis

Fransisca M De Brouwer

Nicolaas J Nordhoek

A system (IPS) and related method for fractional flow reserve, FFR, simulation. The simulation for a range of FFR values for a vasculature portion is based on a composite transfer function which is combined from a weighted sum of global effect transfer functions he, each representing a distinct physical effect that causes a pressure drop. The weights we are gotten from a previous training phase against pressure pi versus flow rate fi 5 sample measurements associated with respective vasculature geometries. The simulated range of FFR values is visualized in a graphics display (GD) as a function of pressure and flow rate values within respective intervals.

Local FFR estimation and visualisation for improved functional stenosis analysis

The present invention refers to 3D rotational X-ray imaging systems for use in computed tomography (CT) and, more particularly, to a fast, accurate and mathematically robust calibration method for determining the effective center of rotation (I) in not perfectly isocentric 3D rotational C-arm systems and eliminating substantially circular ring artifacts (RA) which arise when using such a CT scanner system for acquiring a set of 2D projection images of an object of interest to be three-dimensionally reconstructed. For this purpose, a C-arm based rotational CT scanner comprising at least one radiation detector (D) having an X-radiation sensitive surface exposed to an X-ray beam emitted by at least one X-ray tube (S), each rotating along a non-ideal circular trajectory (T, T) about an object of interest to be three-dimensionally reconstructed from a set of 2D projection images is used for providing geometrical calibration data by scanning a calibration phantom from a plurality of distinct projection directions and calculating, for each projection direction, the 3D positions of the X-ray tube's focal spot and the X-ray detector's center. For approximating the exact 3D position and angular direction of the axis of rotation about which the at least one X-ray tube and the at least one radiation detector rotate, a circular regression technique using a number of mathematically robust least squares fits is applied.

Calibration method for ring artifact correction in non-ideal isocentric 3D rotational X-ray scanner systems using a calibration phantom based rotation center finding algorithm

According to an exemplary embodiment a targeting method for targeting a first object from an entry point to a target point in an object () under examination is provided, wherein the method comprises selecting a two-dimensional image () of the object under examination depicting the entry point () and the target point () and determining a planned path () from the entry point to the target point, wherein the planned path has a first direction. Furthermore, the method comprises recording data representing a fluoroscopic image of the object under examination, wherein the fluoroscopic image is recorded under a second direction so that a normal of the image coincide with the first direction and determining whether the first object is on the determined planned path based on shape and/or position of the projection of the first object in the fluoroscopic image.

Targeting method, targeting device, computer readable medium and program element

It is described a gain calibration for a two-dimensional X-ray detector (), in which the gain coefficients for scattered radiation () and direct radiation () are measured or estimated separately. A weighed average may be applied on the appropriate scatter fraction. The scatter fraction depending gain calibration method produces less ring artifacts in X-ray images as compared to known gain calibration methods, which do not take into account the fraction of scattered radiation reaching the X-ray detector ().

X-ray detector gain calibration depending on the fraction of scattered radiation

Prior to an intervention, a 3D rotational scan is acquired (at block) in respect of a body volume and reconstructed. In addition, three-dimensional image data in respect of the body volume is acquired (at block) using another modality, such as computerised tomography (CT) or magnetic resonance (MR), reconstructed, and prepared for visualisation. During the actual intervention, live two-dimensional fluoroscopic images are acquired (at block), using the imaging system employed to acquire the 3D rotational scan, and processed for visualisation. The 2D image data is registered (at block) to the 3D rotational image data acquired and reconstructed in respect of the body volume of interest, and then a 3D-3D registration process is employed (at block) to register the 3D image data acquired in respect of the same body volume using, for example, CT or MR imaging systems to the 3D rotational image data, and a display module () is used to align the 2D fluoroscopic image and the 3D MR/CT image as a fused or composite image and display the image.

Image processing system and method for registration of two-dimensional with three-dimensional volume data during interventional procedures

An imaging system including an artifact reducer arranged to correct for a ring-shaped artifact in a three-dimensional reconstructed volume. The artifact reducer includes a first stage correction arranged to eliminate structured noise of an output screen of an image intensifier of an X-ray imaging apparatus using a first corrective image. A raw image of a patient is first processed with the first corrective image. The gain-corrected images are forwarded to an image deformation correction where a suitable unwarping function performed. The gain-corrected unwarped images are then made available to a second stage gain correction where a second corrective image is applied resulting in a final set of images with a substantially reduced ring-shaped artifact. The final set of images is made available to an image reconstructor arranged for further processing of the final set of images, the result thereof being visualized on a computer monitor for inspection purposes.

Imaging system, an x-ray imaging apparatus, a method and a computer program arranged for reducing an artifact in a three-dimensional reconstructed volume

An artifact correcting image reconstruction apparatus includes a reconstruction processor () that reconstructs acquired projection data () into an uncorrected reconstructed image (). A classifying processor () classifies pixels of the uncorrected reconstructed image () at least into high, medium, and low density pixel classes. A pixel replacement processor () replaces pixels of the uncorrected reconstructed image () that are of the high density and low density classes with pixel values of the low density pixel class to generate a synthetic image (). A forward projecting processor () forward projects the synthetic image () to generate synthetic projection data (). A projection replacement processor () replaces acquired projection data () contributing to the pixels of the high density class with corresponding synthetic projection data () to generate corrected projection data (). The reconstruction processor () reconstructs the corrected projection data () into a corrected reconstructed image ().

Metal artifact correction in computed tomography

A computed-tomography system comprises a data-processing system arranged to receive attenuation profiles for respective orientations. A lowest representative noise level of the individual attenuation profiles is determined. The attenuation profiles are filtered in dependence of said lowest representative noise level. In particular it is achieved that the filtered attenuation profiles have the lowest maximum noise level among the received attenuation profiles.

Computed-tomography system with filtering

The size of a detail of an object is derived from a data set of data values relating to the object. The data set assigns the data values to positions in a multidimensional space. A direction is selected in the multidimensional space. The spatial resolution of the data set is higher in the selected direction as compared to the spatial resolution in other directions. The size of the detail is derived from data values in the selected direction. The selected direction can extend along the line of intersection which intersects a scanning plane in which the data values are acquired and a transverse plane extending at right angles to the longitudinal axis of the detail. The data values can be acquired an X-ray computed tomography imaging system, a magnetic resonsance imaging system, or a 3D ultrasound imaging system.

Deriving dimensions of a detail of an object

A cross-sectional distribution along a cutting plane is derived from an object data set of data values. The cross-sectional distribution comprises density values. The density values are calculated from data values of the object data set in positions outside the cutting plane. The object data set represents an object to be examined and is, for example, acquired by way of volumetric computed tomography or magnetic resonance imaging. For example, the density values of the cross-sectional distribution are calculated by local (slab) MIP or mIP or by interpolation.

Deriving a cross-sectional distribution from an object data set

The invention relates to a computer tomography apparatus in which the scanning trajectory is shaped as a helix and a conical radiation beam traverses the examination zone. According to the invention, the dimension of the detector window (or the part thereof which is used for the reconstruction) is a factor of 3, 5, 7 . . . larger than the distance between neighboring turns of the helix. Using this geometry, each voxel in the examination zone is irradiated exactly from an angular range of 3&pgr;, 5&pgr;, 7&pgr; . . . when it traverses the cone beam. Such data acquisition yields an improved image quality.

Computer tomography apparatus with a conical radiation beam and a helical scanning trajectory

A computer tomography device includes an X-ray source (1) and an X-ray detection system (3) for forming a number of density profiles of an object to be radiologically examined. A reconstruction unit (4) derives an image signal from the density profiles. A control system (20) adjusts the X-ray source (1) on the basis of a density value of the object and the control system is arranged to adjust the X-ray source on the basis of a part of the object to be examined. The control system is also arranged to adjust the X-ray source on the basis of a reference adjustment of the X-ray source. The reference adjustment is dependent on the part of the object to be examined.

Adjustable computer tomography device

A patient (7) is irradiated by an X-ray source (1) in a computed tomography apparatus. The radiation is subsequently detected by the detector cells (5) of a position-sensitive X-ray detection system (4) and the intensities detected are applied to a computing device (16). Absorption as well as elastic and inelastic scattering of X-rays occur within the patient (7). The data acquired is corrected for elastic (coherent) scatter by deriving a deconvolution function from the elastic scatter function, which deconvolution function is applied to the data. The elastic scatter function is determined, for example by a computer simulation.

Method of and apparatus for computed tomography

A computer tomography device is provided with a reconstruction unit (1) for deriving brightness values of an image from density values. An image processing system (2) for deriving corrected brightness values from the brightness values of the image is arranged to calculate the variation of brightness values of the image in the radial direction and in the tangential direction. The image processing system is also arranged to calculate the deviation between the variation in the radial direction and the variation in the tangential direction and to derive corrected brightness values from brightness values of the image and the deviation.

Correction for ring-like image artefacts

A computer tomography system includes an X-ray tube having an elongate anode across which a beam spot can be displaced, a scanogram being formed by correctly shifting the profiles measured in the various source positions with respect to one another, followed by superposition. Parts of the object which are situated in a selected layer are thus emphasized in an image, parts of the object which are situated outside the selected layer being blurred. When a point of interest in the object is determined by observation of the scanogram, the same apparatus is used to produce a tomography slice image transverse the scanogram image. An important additional advantage consists in that the permissible power to be applied to the X-ray source may be higher. Furthermore, a scanogram thus obtained is not necessarily disturbed by the failure of one or more detectors.

Growing community of inventors

Eindhoven, Netherlands

Jan Timmer