X-ray or gamma ray systems or devices – Specific application – Computerized tomography
Reexamination Certificate
1998-08-25
2001-03-06
Bruce, David V. (Department: 2876)
X-ray or gamma ray systems or devices
Specific application
Computerized tomography
C378S012000, C378S004000
Reexamination Certificate
active
06198791
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates generally to imaging and, more particularly, to scalable multislice imaging systems.
In at least some imaging systems generally referred as computed tomography (CT) systems, 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. X-ray sources typically include x-ray tubes, which emit the x-ray beam at a focal spot. X-ray detectors typically include a collimator for collimating x-ray beams received at the detector, a scintillator adjacent the collimator, and photodiodes adjacent the scintillator.
Dual (two) slice CT systems are known, but at least some of the commercially available dual slice systems have a number of limitations, including balancing scanning speed and z-axis resolution (e.g., as scanning speed increases, z-axis resolution decreases), image quality associated with image reconstruction processing, and flexibility, e.g., such systems cannot collect more than 2 slices of data. Particularly, the known commercially available dual slice systems are not scalable in that such dual slice systems cannot be configured to collect more than two slices of data.
It would be desirable to provide a multislice CT system that can be used to collect one, two or more slices of data. It also would be desirable to provide such a multislice CT system that enables fast scanning speed with good image quality and z-axis resolution.
BRIEF SUMMARY OF THE INVENTION
These and other objects may be attained by a scalable multislice system which, in one embodiment, includes a scalable multi-slice detector, a scalable data acquisition system (SDAS), scalable scan management, control, and image reconstruction processes, and scalable image display and analysis. As used herein, the term scalable generally means that an operator can readily and simply select the desired number of slices and the slice thickness for images to be displayed. In an exemplary embodiment, the system enables the operator to select 1, 2, 4 or more slices to be displayed at a selected slice thickness. By enabling the system operator to make such selections, the image data for different clinical applications can be displayed in a most optimum format. No known multislice system provides an operator with such flexibility.
More specifically, and in an exemplary embodiment, the system includes a host computer coupled to a monitor (user interface) for displaying images and messages to the operator. The host computer is coupled to a keyboard and a mouse to enable the operator to input information and commands to the host computer, e.g., the desire number of slices and slice thickness. The host computer also is coupled to a scan and reconstruction control unit (SRU) which includes image generation controls.
A stationary controller is connected to the SRU, and the stationary controller is coupled to a table controller for controlling motion of the patient table. The stationary controller also is connected, through a slipring, to an on-board (i.e., on the gantry) controller and to a scalable data acquisition system (SDAS). The on-board controller controls operation of the x-ray source and operation of the SDAS, which converts analog signals from the scalable detector to digital data. The x-ray source includes a cam collimator controlled by the on-board controller. The position of the cams of the cam collimator are adjusted based on the desired number of slices and the desired slice thickness.
The system also includes a detector having a number (e.g., 57) of modules. Each module, in an exemplary embodiment, includes a scintillator array and a photodiode array. In the exemplary embodiment, the scintillator and photodiode arrays each are 16×16 arrays. The photodiodes are coupled to a switching apparatus which, in the one embodiment, includes an array of FETs, and the FETs control the combination of photodiode outputs based on the desired number of slices and slice thickness input the operator.
In operation, and during a scan (e.g., a helical or axial scan), the photodiode outputs are supplied to the SDAS, via the FETs, for analog to digital conversion. The digital outputs from the SDAS are then supplied to the SRU via the slipring for image generation. Specifically, the SRU reconstructs images from the collected data, and such reconstructed images can be displayed to the user on the monitor or archived, or both.
The above described scalable multislice system can be easily and simply operated to collect one, two, or more slices of data. Such system also enables fast scanning speed with good image quality, z-axis resolution, and a low x-ray tube load.
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Besson Guy M.
Hampel Willi W.
He Hui David
Hoffman David M.
Hu Hui
Bruce David V.
Cabou Christian G.
General Electric Company
Hobden Pamela R.
Price Phyllis Y.
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