X-ray or gamma ray systems or devices – Specific application – Computerized tomography
Reexamination Certificate
1998-08-25
2001-06-12
Church, Craig E. (Department: 2882)
X-ray or gamma ray systems or devices
Specific application
Computerized tomography
C378S207000
Reexamination Certificate
active
06246743
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates generally to computed tomography (CT) imaging and more particularly, to troubleshooting of an imaging system.
In at least one known CT system configuration, an x-ray source projects a fan-shaped beam which is collimated to lie within an X-Y plane of a Cartesian coordinate system and generally referred to as the “imaging plane”. The x-ray beam passes through the object being imaged, such as a patient. The beam, after being attenuated by the object, impinges upon an array of radiation detectors. The intensity of the attenuated beam radiation received at the detector array is dependent upon the attenuation of the x-ray beam by the object. Each detector element of the array produces a separate electrical signal that is a measurement of the beam attenuation at the detector location. The attenuation measurements from all the detectors are acquired separately to produce a transmission profile.
In known third generation CT systems, the x-ray source and the detector array are rotated with a gantry within the imaging plane and around the object to be imaged so that the angle at which the x-ray beam intersects the object constantly changes. A group of x-ray attenuation measurements, i.e., projection data, from the detector array at one gantry angle is referred to as a “view”. A “scan” of the object comprises a set of views made at different gantry angles during one revolution of the x-ray source and detector.
In an axial scan, the projection data is processed to construct an image that corresponds to a two dimensional slice taken through the object. One method for reconstructing an image from a set of projection data is referred to in the art as the filtered back projection technique. This process converts that attenuation measurements from a scan into integers called “CT numbers” or “Hounsfield units”, which are used to control the brightness of a corresponding pixel on a cathode ray tube display.
To reduce the total scan time, a “helical” scan may be performed. To perform a “helical” scan, the patient is moved while the data for the prescribed number of slices is acquired. Such a system generates a single helix from a one fan beam helical scan. The helix mapped out by the fan beam yields projection data from which images in each prescribed slice may be reconstructed.
At least one known CT imaging system utilizes a detector array and a data acquisition system (DAS) for collecting image data. The detector array includes detector cells or channels that each produce an analog intensity signal which is representative of the x-ray energy impinged upon the cell. The analog signals are then supplied to the DAS for conversion to digital signals. The digital signals are then used to produce image data. Image artifacts, with the potential for patient mis-diagnosis, can be produced by the degradation or failure of individual detector cells, the DAS, and detector to DAS interconnections. Detector cell degradation as measured by gain non-linearity typically produces ring or band annoyance artifacts. In addition, failure of cells at the center of the detector results in a spot on the image, which could be interpreted as a tumor or lesion. Similarly, degradation and failure of the interconnections and DAS impact the image quality. As a result of the complexity of the imaging system troubleshooting of components may be time consuming and difficult.
Accordingly, it is desirable to provide an imaging system which detects component failure and provides fault isolation information. It would also be desirable to provide such a system without increasing the cost and complexity of the system.
BRIEF SUMMARY OF THE INVENTION
These and other objects may be attained in an imaging system which, in one embodiment, alters the configuration of a detector array and a data acquisition system to determine degraded component performance and generate fault isolation information. The imaging system includes a multislice detector array having a plurality of detector cells, an x-ray source for radiating an x-ray beam toward the detector array, a data acquisition system (DAS), and a computer.
By altering the configuration of the detector array and channel selection within the DAS, degraded components may be isolated for replacement. More specifically, detector intensity data is generated and converted by the DAS for a reference scan. If the scan data does not conform to reference data, the configuration of the detector array and DAS are altered and additional reference scans are performed to provide fault isolation information. More specifically, by altering the configuration of the detector array to include different combinations of cells, different detector intensity data are generated to identify degraded detector performance. In addition, the DAS configuration is altered so that the detector intensity data is converted by one or any number of DAS channels. By comparing the results of the different combinations, degraded interconnection and DAS performance is identified and fault isolation information is generated.
By utilizing the multislice detector array and the DAS, specific degraded components are identified. In addition, the described system reduces the time required to isolate a failure and produces repeatable results without increasing the cost and complexity of the system.
REFERENCES:
patent: 4965726 (1990-10-01), Heuscher et al.
patent: 5473663 (1995-12-01), Hsieh
He Hui David
Kopp, III Rudolph T.
Schanen Paul C.
Seidenschnur George E.
Armstrong Teasdale LLP
Cabow Christian G.
Church Craig E.
General Electric Company
LandOfFree
Methods and apparatus for troubleshooting scaleable... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Methods and apparatus for troubleshooting scaleable..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Methods and apparatus for troubleshooting scaleable... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2522014