General Electric Company

Other

Armin H Pfoh

Hui Hu

Thomas L Toth

Norbert Joseph Pelc

Peter Michael Edic

Guy M Besson

Jiang Hsieh

David Michael Hoffman

Robert F Senzig

Michael F Gard

Carl R Crawford

Clifford Bueno

Harry Israel Ringermacher

Stanley Haim Fox

Hui David He

Jonathan Alan Murray

Shankar Visvanathan Guru

George E Seidenschnur

Willi W Hampel

Gary R Strong

Thaddeus Raymond Ulijasz

Jiunn-Ru Jeffrey Huang

A flexible imager, for imaging a subject illuminated by incident radiation, includes a flexible substrate, a photosensor array disposed on the flexible substrate, and a scintillator. The scintillator is disposed so as to receive and absorb the incident radiation, is configured to convert the incident radiation to optical photons, and is optically coupled to the photosensor array. The photosensor array is configured to receive the optical photons and to generate an electrical signal corresponding to the optical photons. A digital imaging method for imaging subject includes conforming flexible digital imager to subject, the subject being positioned between flexible digital imager and a radiation source. The method further includes activating radiation source to expose the subject to radiation and collecting an image with the flexible digital imager.

Imager

An apparatus and a method of processing a collection of uncorrected radiographs are described with the apparatus comprising an X-ray scatter compensator and a controller. The compensator is configured for iteratively generating a refined value of a normalized estimated X-ray scatter signal corresponding to an uncorrected radiograph of said collection of uncorrected radiographs. The controller is configured to be coupled to the compensator and further configured to subtract said refined value of said normalized estimated X-ray scatter signal from a corresponding normalized total X-ray signal of a respective one of said uncorrected radiographs so as to form a corresponding corrected radiograph.

Iterative X-ray scatter correction method and apparatus

A single-slice data acquisition system (DAS) for a CT imaging system is time-multiplexed to measure more than one signal over the DAS standard sampling time interval. In one embodiment, a detector element includes a scintillator and two photodiodes aligned with respective portions of the scintillator. Each photodiode generates a signal based on the scintillator output. The signal from one of the photodiodes is subjected to a time-dependent gain during consecutive sampling intervals. The gain-adjusted signal and the signal from the other photodiode are combined, and the combined signal is processed to obtain an estimate of the z-derivative of the signal. The estimated z-derivative is then used to generate a high quality image.

Methods and apparatus for time-multiplexing data acquisition

Focal spot position determination systems having a high sensitivity to focal spot movement for use in connection with multi-slice computed tomography imaging systems are described. In one embodiment, the determination system is configured for application in a two slice system. Signals from adjacent detector cells in separate rows are compared to determine focal spot position. More particularly, the signal intensity A of the signal output by a first detector cell and the signal intensity B of the signal output by the second detector cell are related to the position of the focal spot. That is, the z position of the centerline of the fan beam can be determined by relating the signal intensities A and B according to the ratio &lsqb;(A&minus;B)/(A&plus;B)&rsqb;. Such ratio is representative of the beam location and can be used to control adjustment of the imaging system pre-patient collimator to maintain the beam in the desired position.

Methods and systems for determining x-ray beam position in multi-slice computed tomography scanners

The present invention is, in one aspect, an imaging system having a detector that has multiple detector cells extending along a z-axis, the detector being configured to collect multiple slices of data; and a scalable data acquisition system configured to convert signals from the detector to digital form, the scalable data acquisition system having a plurality of converter boards each with a plurality of channels, the channels and detector cells having an interweaved coupling to reduce susceptibility to band artifact.

Scalable multislice imaging system

The present invention, in one form, is a system for reducing contribution of scatter signal to an image of an object constructed from projection data acquired during a computed tomography scan. The system includes an x-ray source which emits an x-ray beam toward a detector array. A collimator plate is movable with respect to the detector array. The system is configured to move the collimator between a first position and a second position. In the first and second positions, the collimator does not cover the detector array, i.e., the collimator does not collimate the x-ray beam impacting the detector array. When moving between the first and second positions, the collimator at least partially covers the detector array, i.e., the collimator at least partially collimates the x-ray beam impacting the detector array. A first signal intensity at the detector array is obtained when the collimator is in the first position and a second signal intensity at the detector array is obtained when the collimator is moved between the first and second position. The determined signal intensities are then utilized to determine the scatter signal of the x-ray beam and to generate substantially uncorrupted projection data.

Methods and apparatus for scanning an object in a computed tomography system

A multi-slice or volumetric CT system has a 2D array of detector elements arranged in columns along the slice direction and rows along the in-slice direction. Channels in a digital acquisition system connect to the respective columns and a switch assembly is operated during a scan to sequentially enable detector elements in each column either one or two at a time. By enabling two elements at a time, the SNR of the acquired data is increased and the expected resolution loss in the slice direction is compensated for by detector wobbling.

Detector signal integration in volumetric CT scanner detector arrays

An attenuator and detector cell arrangement for generating a signal ratio representative of focal spot position is described. The ratio is highly sensitive to focal spot position and facilitates generating, or reconstructing, a high quality image from the projection data. Further, and importantly, even if one detector cell is fully flooded, the signal intensity from such cell will vary depending upon the alignment between the focal spot and attenuator slot. Therefore, the focal spot movement detector is effective for detecting fan beam movement even if the detector cell is fully flooded. In one embodiment, the x-ray beam attenuator is configured to be positioned over the detecting surface of z-position detection cells. Slots or openings extend through the attenuator so that at least a portion of each detector cell is in free communication with an x-ray beam from the x-ray source. The slots are positioned and oriented so that one detector cell signal has its highest x-ray response at one extreme position along the focal spot trajectory and the other detector cell has its highest x-ray response at the other extreme position along the focal spot trajectory.

Methods and apparatus for detecting beam motion in computed tomography

Image artifacts are reduced in a volumetric CT scanner system by decreasing the detector pitch along one or both dimensions of a 2D detector array. Four different embodiments for reducing detector pitch without reducing the size of each detector element are disclosed.

X-ray detector array with reduced effective pitch

An x-ray computed tomography system for helically scanning a patient translates the patient as projections of the patient at various beam angles are obtained. The projection data are weighted prior to reconstruction to account for multiply measured projection data and the deviation of the cone beam from a parallel beam approximation.

Projection domain reconstruction method for helical scanning computed

A 3rd generation CT system produces gain calibration factors (.gamma.) for each channel of a detector array while a scan is being performed. Redundant views are acquired during the scan but the x-ray intensity values in the second view are shifted to the adjacent detector channel by focal spot wobbling the x-ray source. Gain calibration factors (.gamma.) are calculated using the ratio (.beta.) of x-ray intensity values measured at adjacent detector channels.

Detector channel gain calibration using focal spot wobble

An x-ray computed tomography system for helically scanning a patient translates the patient as projections of the patient at various beam angles are obtained. A cone beam reconstruction method, which accounts for the divergence of the rays of a fan beam of x-rays, is used to reconstruct multiple narrow slices which are combined to provide a larger slice with an improved slice profile. The conical shape of the fan beam causes some voxels to be scanned more than once for a given beam angle and this extra data is weighted and combined with its counterpart data to improve the quality of the image.

Reconstruction method for helical scanning computed tomography apparatus

An imaging system includes a linear detector array which measures x-rays passing through a patient from an x-ray source. A mask disposed over the detector array has staggered segments that block x-rays and divide the detector array into a pair of slice planes. Signals from the detector elements receiving x-rays in respective ones of the two slice planes are used to separately reconstruct a slice image for each of the two slice planes.

Multi-slice x-ray CT using a detector mask

A CT apparatus employing a cone beam of x-rays reduces image artifacts by employing full as opposed to half scans of less than 360.degree.. The present invention recognizes that rays of a cone beam that cross the imaging plane are not redundant with opposing rays in the scan, as is the case with the rays within the imaging plane. In a second embodiment, half scans of less than 360.degree. are obtained using in-plane and cross-plane rays of the cone beam and the data from the in-plane rays is used to estimate the missing data from that collected with the cross-plane rays.

Tomographic image reconstruction using cross-plane rays

An x-ray computed tomography system for helical scanning, translates a patient as projections of the patient at various beam angles are obtained and employs a detector array having multiple rows displaced along the direction of translation. The intensity signals from the multiple rows are combined to produce a composite projection having an improved beam profile along the translation direction. The composite projection is generated by adding together intensity signals obtained for detector elements in each column, at a given beam angle, and for related columns measuring rays having angles differing by x radians or an integer multiple thereof. The intensity signals are selected so that their points of acquisition cluster closely about the position of the desired slice plane.

Growing community of inventors

New Berlin, WI, United States of America

Armin H Pfoh