Siemens Aktiengesellschaft

Siemens Aktiengesell Schaft

Wolfgang Haerer

Thomas Mertelmeier

Karl Barth

Karl Wiesent

Dietrich Hassler

Michael Zellerhoff

Guenter Lauritsch

Heinz Eschenbacher

Gunter Schwierz

Lothar Baetz

Ernst-Peter Ruehrnschopf

In a device and associated method for reconstruction and visualization of projection data, projection data are stored per slice and are subjected to an image reconstruction procedure in parallel within arbitrary slice planes in a processor-controlled filtering process that is executed n times, wherein volume data that are created can already be made available (loaded) for a direct visualization.

Device and method for reconstruction and visualization of projection data

In a method for correction of scatter radiation errors in radiography and computer tomography, using flat panel detectors, initially an estimation of a scatter radiation distribution Sr(y,z) is undertaken, and a standard correction term &#x3b4;pis subsequently calculated. Noise filtering of the standard correction term &#x3b4;pwith F(&#x3b4;p) is implemented and subsequently the noise-filtered standard correction term F(&#x3b4;p) is added to the logarithmized measured total projection data p. The noise filtering can be implemented adaptively dependent on a previously-determined local noise variance. The method can be implemented in a radiography system and/or by a computer for generation and/or processing of projective and/or tomographic exposures, with a memory containing program codes causing the computer in operation to execute the steps of the method.

Scatter radiation correction in radiography and computed tomography employing flat panel detector

In a tomosynthetic image reconstruction method and diagnostic device operating with such a method, a tomosynthetic 3D x-ray image is reconstructed by a discrete filtered back projection from a number of individual digital projection data recorded from different project angles within a restricted angular range, in which at least one filtering is performed with a convolution kernel that, in the local area outside of its central value, corresponds to an exponential function.

Tomosynthetic image reconstruction method, and diagnostic device operating according to the method

In a method for reconstruction of a three-dimensional image of an object scanned in linear or circular fashion in the context of a tomosynthesis. The object is transirradiated with X-rays from various projection angles &phgr; for the recording of the projection images, and the radiation exiting from the object is recorded by a detector that supplies digital output image signals. The output image signals representing the projection image data are supplied to a computer for image reconstruction. In the context of the reconstruction a filter is first produced, on the basis of the following steps: A 3D transmission function H (&ohgr; ,&ohgr; ,&ohgr; ) is calculated from the recording geometry for the individual projection image recording and the back-projection of the individual projection images into the 3D reconstruction image volume. By approximation, the 3D transmission function H (&ohgr; ,&ohgr; ,&ohgr; ) is inverted for the determination of an inversion function H (&ohgr; ,&ohgr; ,&ohgr; ). A 3D filtering function H (&ohgr; ,&ohgr; ,&ohgr; ) is produced dependent on one or more desired image characteristics of the reconstruction image. A resulting 3D filtering function H (&ohgr; ,&ohgr; ,&ohgr; ) is determined by multiplication of the 3D filtering function H (&ohgr; ,&ohgr; ,&ohgr; ) and the inversion function H (&ohgr; ,&ohgr; ,&ohgr; ). A 2D filtering function H (&ohgr; ,&ohgr; ) is determined from the resulting 3D filtering function H (&ohgr; ,&ohgr; &ohgr; ) by coordinate transformation of the 3D object space into the 2D projection image space of the respective individual projection images at the projection angle &phgr;. After calculating the filter, the reconstruction of the image takes place in the computer by application of the 2D filtering function H (&ohgr; ,&ohgr; ) to the associated individual projection image data, and production of the reconstruction image by back-projection of the filtered individual projection image data, into the 3D reconstruction image volume.

Method for reconstructing a three-dimensional image of an object scanned in the context of a tomosynthesis, and apparatus for tomosynthesis

In an x-ray diagnostic apparatus for tomosynthesis or laminographic imaging using a patient positioning table, an x-ray source which emits an x-ray beam on one side of the patient positioning table, an x-ray detector arranged on the other side of the patient positioning table for the capture of the x-ray beam and for producing digital images, a device for movement of the x-ray source, a device for shifting of the x-ray detector and a device for superimposing the digital images so that only the details lying in a specific longitudinal slice for an examination subject are sharply imaged, the x-ray detector is rotated relative to the movement direction at an angle.

X-ray diagnostic apparatus with relatively moved x-ray source and detector

A sectional plane of the examination subject is first scanned by focused ultrasound transmission beams in an adaptation phase. Disturbing effects from the reflected echo signals which are caused by the inhomogenities in the tissue are thereby measured. In this adaptation phase, correction values for the delay time of the signals of the elemental transducers of the ultrasound array in comparison to the standard focusing are also derived from the measured values. In a following B-image imaging phase, the delay times of the active aperture are then varied dependent on the correction values during the emission and/or during reception. The disturbing effects are thereby compensated. A method and apparatus are disclosed which are especially well-suited for linear array systems and for patients having inhomogeneous tissues.

Method and apparatus for adaptive focusing in a medical ultrasound

In an illustrated embodiment, the fan shaped beam of penetrating radiation has a central ray directed offcenter relative to a row of detectors e.g. by a distance corresponding to one-fourth the detector separation. In this way, for each projection with a given central ray angle, further points can be derived by interpolation using the measurements from other projections. With a given number of detector elements, the number of points per projection can be doubled in this way.

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Erlangen, Germany

Wolfgang Haerer