Siemens Medical Solutions USA, Inc.

Other

Siemens Corporate Research, Inc.

John C Engdahl

Jianzhong Qian

Guo-Qing Wei

Jinhun Joung

Samir Chowdhury

James Frank Caruba

Glenn F Knoll

Ronald A Rojeski

Douglas Scott McGregor

John Thomas Pawlak

Darrell Burckhardt

Douglas Jay Wagenaar

Dennis E Persyk

William L Rogers

Eric Q Chen

A partitioned pipeline read-out circuit architecture eliminates real-time constraints from off-chip read-out control electronics in a solid-state radiation detector system, so that an efficient decoupled architecture is possible. The front-end electronics includes a multi-channel ASIC with independently triggered charge sensitive pre-amplifiers, shaper circuits, and switched sample-and-hold capacitor circuits for each photodiode or pixel of the detector module. With this structure, individual photodiodes of the photodetector array can detect and store scintillation events independently and randomly. The ASIC is interfaced to an external successive approximation A/D converter for conversion and subsequent input to a data processing apparatus.

Burst-mode readout for solid state radiation detectors using partitioned pipeline architecture

An improved method of, and apparatus for, nuclear imaging takes advantage of the ability to determine the depth of gamma ray/electron interaction within a semiconducting gamma ray detector to determine the (most highly probable) location of the first gamma ray/electron interaction within the detector. Lines of interaction constructed between opposing detector arrays, extending between the location of the first gamma ray/electron interaction in each detector associated with the coincident detection of gamma radiation, permits a positron-emitting object of interest to be imaged according to protocols known in the art, but with better spatial resolution than previously believed to have been known.

Nuclear imaging using three-dimensional gamma particle interaction detection

A dynamic Single Photon Emission Computed Tomography (SPECT) system utilizes an array of modular detectors structured in a dome shape and being independently tiltable in polar or azimuth angle. The system can be used to image cardio-vascular studies as well as other quantitative studies and 3D imaging studies, without requiring movement or motion of the detectors.

Stationary multi-pinhole cardio vascular SPECT system

A gamma camera having a scintillation detector formed of multiple bar detector modules. The bar detector modules in turn are formed of multiple scintillation crystal bars, each being designed to have physical characteristics, such as light yield, to achieve a sufficient spatial resolution for nuclear medical imaging applications. According to another aspect of the invention, the bar detector modules are arranged in a three-dimensional array, where each module is made up of a two-dimensional array of bar detectors with at least one photosensor optically coupled to each end of the module. Such a camera can be used for both PET (coincidence) and single photon imaging applications. According to another aspect of the invention, a bar detector gamma camera is provided, which utilizes an improved positioning algorithm that greatly enhances spatial resolution in the z-axis direction (i.e., the direction along the length of the scintillation crystal bar).

Nuclear imaging system using scintillation bar detectors and method for event position calculation using the same

A system and method for appearance-based object detection includes a first portion capable of brightness and contrast normalization for extracting a plurality of training images, finding eigenimages corresponding to the training images, receiving an input image, forming a projection equation responsive to the eigenimages, solving for intensity normalization parameters, computing the projected and normalized images, computing the error-of-fit of the projected and normalized images, thresholding the error-of-fit, and determining object positions in accordance with the thresholded error-of-fit; and optionally includes a second portion capable of forming eigenimages for multiresolution for sub-sampling the training images, forming training images of coarse resolution in accordance with the sub-sampled images, computing eigenimages corresponding to the training images of coarse resolution, interpolating the eigenimages for coarse resolution, performing orthonormalization on the interpolated images by singular value decomposition, and providing pseudo-eigenimages corresponding to the orthonormalized images for a finer resolution.

Integrated approach to brightness and contrast normalization in appearance-based object detection

A multi-pinhole collimator nuclear medical imaging detector divides a target object space into many non-overlapping areas and projects a minified image of each area onto a segmented detector, where each segment functions as an independent detector or imaging cell. Septa may be provided between the collimator and the detector, to physically isolate the segments.

Multi-pinhole collimation for nuclear medical imaging

A method and apparatus for improving the energy resolution, sensitivity and other aspects of a x-ray or gamma ray detector by using modified acquisition electronics in conjunction with low leakage current photodiodes. Specifically, increasing the integration time of the sample circuits without degrading energy resolution due to parallel noise in order to improve energy resolution and sensitivity, and to allow new electronics designs.

Low noise, long integration time acquisition for radiation detectors

A system and method for automatic quantitative assessment of myocardial image quality includes a liver-heart artifact quantification unit for providing a sequence of images, detecting the heart position in each image, segmenting non-heart activity relative to the detected heart positions, measuring the liver-heart effect in each image based on the segmentations, fusing the measurements obtained in each image, and determining a quality number for the plurality of images responsive to the fused measurements; and also includes a heart detection unit for receiving the image sequence, generating a region of interest comprising the heart by 1-D pseudo-motion analysis of the image sequence, localizing the heart center by a training-based algorithm, fitting a curve to the localized heart centers of each image in the sequence, refining the heart center positions of localized heart centers falling outside of a tolerance distance from the fitted curve, and determining a bounding circle comprising the heart in accordance with the localized and refined heart center positions.

Automatic and quantitative assessment of image quality in SPECT myocardial perfusion imaging

A radionuclide scanner in which multiple detectors are equipped with collimators such that a circular rotation of the detector around a target provides the movement needed for collimator sampling. This collimator sampling is accomplished through strategic placement of the detector heads relative to each other such that for any given projection, a complete imaging of the projection is acquired by summing the complementary contributions of the multiple detector heads at the projection under consideration.

High resolution, multiple detector tomographic radionuclide imaging based upon separated radiation detection elements

A gamma camera having a system for performing a quality control procedure with minimal to no intervention from a user of the camera. In one aspect, the gamma camera includes a relatively weak radioactive source positioned at a fixed or known location relative to the gamma camera scintillation crystal and positioned so that the entrance window side of the crystal is facing the source, wherein the photons emitted from the source have an energy that is below the energy of photons used for diagnostic imaging. The response of the gamma camera photo-multiplier tubes to the absorption events caused by the radioactive source when the camera is idle can be compared to a baseline response to determine whether one or more of the PMTs need to be adjusted.

System and method for calibrating and tuning a gamma camera

The present invention provides a method for discriminating between detected radiation events, so that the sensitivity of the radiation detector may be preserved without causing the inclusion of a large number of the undesired radiation events. This method includes the steps of: (1) empirically determining the energy response function of the radiation detector; and (2) then using the energy response function during the actual detection process to differentiate between the desired and undesired radiation events. Generally, the energy response function for each of the detectors is determined by simulating the condition for the subsequent, actual measurement. During this process, the detector is illuminated with a uniform stream of radiation to be measured. The detector should be exposed to a large number of radiation rays, and the number of undesired rays is minimized. For example, the detector will be exposed to only direct, unscattered radiation. This simulation produces an energy response function for the detector in conditions that approximate the actual measurement. Then, when taking actual measurements in the second step, a least squares estimate of the number of desired, unscattered events is produced by taking the dot product of (1) the spectrum acquired during actual measurement and (2) a weighting vector determined from the empirically determined energy response function.

Method of gamma ray event selection

A radiation assisted electron emission device uses semiconductor or semi-insulator material formed with an emission mechanism such as a field emission tip, a thermionic emission device, or a negative electron affinity emitter as a source of electrons. The material is irradiated with a source of radiation, such as electromagnetic radiation, neutron radiation, or charged particle radiation, which excites electron-hole pairs in the material to generate a population of free conducting electrons. The electrons are driven to the emission mechanism by a suitable transport process, such as diffusion or drift. The electron emission device has applicability to a broad range of technologies where an electron beam or current is used.

Radiation assisted electron emission device

According to one embodiment of the invention, a variable length correlation method is provided for compensating for body motions and heart creep in a sequence of image frames obtained by single-photon emission computed tomograph (SPECT) myocardial perfusion imaging. Abrupt body motions, gradual body motions, and heart upward creep are detected and corrected in the sequence of image frames, based on varying correlation lengths. A linear transformation is used to compensate for appearance changes of the heart under different acquisition angles so as to achieve high accuracy of motion detection and correction. The detecting and correcting step is applied in the two-dimensional image domain. The method also includes the steps of detecting and excluding high intensity, non-heart regions in a particular image frame so that non-heart motions such as bowel gas, spleen, and liver motions are excluded from being involved in the motion detection and correction procedure.

Variable-length correlation method for motion correction in SPECT myocardial perfusion imaging

A gamma ray imaging detector for nuclear medical imaging includes an array of photodiode detectors provided on opposite surfaces of a scintillating crystal. By measuring the relative distribution of detection signal intensities produced by each photodiode in each array, it becomes possible to measure the depth of interaction of a gamma ray absorption event along the Z axis direction of the crystal in addition to its spatial position in the X-Y plane of the crystal and its absorption energy. The value of the measured depth of interaction is subsequently used in refining the calculation of the spatial location and improving the performance characteristics of the imaging detector.

Gamma ray imaging detector with three dimensional event positioning and

A scintillation camera is provided with a scintillation crystal assembly having multiple crystal layers for interacting with various photon energy levels. The camera performs imaging of conventional nuclear medicine radioisotopes as well imaging of high energy isotopes used in PET (Positron Emission Tomography) applications. The multiple crystal layers have the effect of doubling the sensitivity of the camera to high energy photons, while retaining the performance characteristics needed for conventional low energy photon imaging.

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Lake Forest, IL, United States of America

John C Engdahl