Error detection/correction and fault detection/recovery – Pulse or data error handling – Digital data error correction
Reexamination Certificate
1998-08-25
2001-09-18
Chung, Phung M. (Department: 2133)
Error detection/correction and fault detection/recovery
Pulse or data error handling
Digital data error correction
C714S746000
Reexamination Certificate
active
06292919
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates generally to data communications and, more particularly, to exchanging data in an imaging system
In at least one known computed tomography (CT) imaging 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, or view 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 the 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.
At least one known CT imaging system sends imaging data collected by the detector array across a slip-ring having a shoe and a copper ring mechanism at a rate of about 1.5 megabytes (MB) per second during normal scanning. A receiver of the imaging data checks the data and, if the data is correct, sends an acknowledgment to a transmitter that the correct imaging data was received. Using this method, the slip-ring has the capability of transmitting data at about 5.0 MB per second, and uses the excess bandwidth for re-transmission of the imaging data in the event of an error. However, as scan speeds are increased and additional data is collected in the detector array, data must be transmitted over the slip-ring at a faster rate. As a result, there is insufficient bandwidth to provide a communication path back from the receiver of the imaging data to the transmitter. In addition, because corrected data must be re-transmitted when an error occurs, scanning speeds are limited.
To increase the rate of data transfer within the imaging system, it is desirable to provide communication system, or circuit, which transmit data without requiring an acknowledgment be sent from the receiver to the transmitter. It would also be desirable to provide such a circuit which corrects data errors without re-transmitting the imaging data.
BRIEF SUMMARY OF THE INVENTION
These and other objects may be attained by an imaging system which, in one embodiment, includes a communication system, or circuit, transmits imaging, or CT, data from a data acquisition system to a computer or image reconstructor. The communication system includes a transmitter for encoding and transmitting the imaging data and a receiver for receiving and decoding the imaging data.
In one aspect, the present invention is directed to transmitting imaging data across a slip-ring at a high rate of speed without transmitting information from the receiver to the transmitter. More specifically, the transmitter receives parallel data from the data acquisition system and converts the parallel byte data into a serial stream of data. The serial data is transmitted across the slip-ring 1 bit at a time to the receiver. The receiver then decodes the serial data into parallel byte data. More specifically, the encoded data includes command codes, message blocks, and SYNC data. The command codes include data so that the receiver starts decoding the serial data at the proper time. The message data includes the imaging data and Cyclic Redundancy Check (CRC) data representative of the transmitted imaging data. The CRC data is utilized by the receiver to detect and correct errors in the transmitted imaging data. The SYNC data is utilized to synchronize the receiver with the transmitter.
The above described imaging system communication circuit transmits high-speed data across an imaging system slip-ring without requiring an acknowledgment be sent from the receiver to the transmitter. In addition, the communication circuit corrects data errors without re-transmitting the data.
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PCI Local Bus specification, Revision 2.1, effective Jun. 1, 1995, available from PCI Special Interest Group, Portland, OR. Total of 9 pages from chapters 1,2, and 3.
Fries Mark David
Pearson, Jr. Phil E.
Armstrong Teasdale LLP
Cabou Christian G.
Chung Phung M.
General Electric Company
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