摘要:
A method and apparatus for use with a volumetric computed tomography (CT) scanning system. In accordance with the present invention, the volumetric CT scanning system utilizes an area detector to acquire projection data. The acquired projection data is stored in memory. The projection data corresponding to groups of pixels of the detector is then rebinned to thereby reduce the amount of projection data that will be utilized in performing an initial volumetric reconstruction of the image. The reconstructed image may then be processed to identify particular regions of interest, such as a pathology. If a particular region of interest is identified, all of the projection data corresponding to the region is then used to retrospectively reconstruct a high resolution image of the region of interest. The retrospectively reconstructed high resolution image can then be processed and analyzed to further evaluate the region of interest.
摘要:
The present invention provides a model and a method and apparatus for utilizing the model to simulate an imaging scenario. The model is mathematically defined by analytical basis objects and/or polygonal basis objects. Preferably, the model is a model of the human heart and thorax. Polygonal basis objects are only used to define structures in the model that experience torsion, such as certain structures in the heart that experience torsion during the cardiac cycle. The manner in which the basis objects comprising the model are transformed by scaling, translation and rotation is defined for each basis object. In the case where a basis object experiences torsion, the rotation of the basis object will change as a function of the length along the axis of the basis object about which rotation is occurring. During an imaging system simulation, the model is utilized by a forward projection routine, which integrates the linear attenuation coefficients associated with the rays emitted by a simulated x-ray source and collected by a simulated detector array to obtain line integrals corresponding to forward projection data. The forward projection data is then processed to take into account the physics of the imaging technology, the x-ray source and the detector array. The processed projection data is then processed and back-projected by a reconstruction modeling routine to produce a reconstructed representation of the model of the heart as a function of time.
摘要:
An x-ray imaging system images an object by transmitting primary signals and includes a collimator placed between detectors of the x-ray imaging system. The collimator reduces respective scatter components of total signals including a primary signal component and a scatter signal component. One of the detectors detects the total signals, the collimator collimates the primary signals of the total signals focally aligned with the collimator and traveling through the one of the detectors, another of the detectors detects the collimated, primary signals. The x-ray imaging system reduces the scatter components of the total signals detected by the one of the detectors based on the detected, collimated signals and the corresponding, detected, total signals. In another aspect, a detector includes regions of reduced absorption.
摘要:
A method for arranging detector sections for an imaging system that has a field of view that is defined by a rotational axis and imaging geometry is provided. The method includes providing a plurality of detector sections, and arranging the detector sections in an asymmetric arrangement about a central axis of the field of view.
摘要:
Techniques, hardware, and software are provided for quantification of extensional features of structures of an imaged subject from image data representing a two-dimensional or three-dimensional image. In one embodiment, stenosis in a blood vessel may be quantified from volumetric image data of the blood vessel. A profile from a selected family of profiles is fit to selected image data. An estimate of cross sectional area of the blood vessel is generated based on the fit profile. Area values may be generated along a longitudinal axis of the vessel, and a one-dimensional profile fit to the generated area values. An objective quantification of stenosis in the vessel may be obtained from the area profile. In some cases, volumetric image data representing the imaged structure may be reformatted to facilitate the quantification, when the structural feature varies along a curvilinear axis. A mask is generated for the structural feature to be quantified based on the volumetric image data. A curve representing the curvilinear axis is determined from the mask by center-finding computations, such as moment calculations, and curve fitting. Image data are generated for oblique cuts at corresponding selected orientations with respect to the curvilinear axis, based on the curve and the volumetric image data. The oblique cuts may be used for suitable further processing, such as image display or quantification.
摘要:
An apparatus and method used to calibrate a gamma camera include an energy source and intensity selector and an energy weighting device. The energy source provides an energy output, such as an electrical current. The intensity selector is connected to the energy source and adjusts the energy output to a predetermined energy level that corresponds to an intensity of a predetermined radioactive source. The energy weighting device is also connected to the energy source and gamma camera, and the spatial compensator creates calibration signals from the energy output of the energy source. The calibration signals are supplied to the gamma camera and used during calibration of the gamma camera in lieu of energy signals produced by the gamma camera in response to a radioactive source.
摘要:
A method of forming a planar semiconductor device, such as an array of APDs, includes the steps of doping a substantially planar block of n type semiconductor material with a p type dopant in accordance with a selected pattern to form a plurality of n type wells in the block surrounded by a foundation of p type semiconductor material. Each n type well is disposed so as to respectively adjoin a first surface of the block and such that a respective p-n junction is formed between the n type material in the well and the p type material foundation. The n type semiconductor material in each well has a substantially constant concentration of n type dopant throughout the n type material; the concentration of p type dopant in the foundation has a positive gradient extending from the p-n junction towards the second surface such that the peak surface electric field of the p-n junction in each well is less than the bulk electric field of the same p-n junction.