US5241181A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Coincidence detector for a PET scanner
Assignee: General Electric Co
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Filing: 1992-07-27
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Granted: 1993-08-31
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Expires: 2012-07-27
Abstract
Abstract A PET scanner includes a coincidence detector circuit which compares time markers produced by a ring of detector modules. Detector module outputs are sampled every 250 nanoseconds and assembled into event data packets which are time multiplexed through the coincidence detector circuit. The coincidence detector circuit is formed around a set of ASICs which perform the comparisons necessary to detect coincidence events. Coincidence event data packets are sorted into sinograms and used to reconstruct images.
Inventors
- 👤 John D. Mertens
- 👤 William L. Bhend
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-06 02:44
CPC Classifications
G; G01; G01T; G01T1/00; G01T1/29; G01T1/2914; G01T1/2985; A; A61; A61B; A61B6/00; A61B6/02; A61B6/03; A61B6/037
Claims Analysis
Total Claims: 15
Claim 1
Independent Claim
264 words
A positron emission tomographic scanner which comprises: detector means having a plurality of detector modules which produce a corresponding plurality of event data packets during a sample period, each event data packet indicating the location of the detector module which produced it and including a time marker indicative of the time at which a scintillation event was detected by the detector module; a coincidence detector circuit connected to receive and store the plurality of event data packets produced during each sample period, the coincidence detector circuit including: a) a comparator circuit coupled to receive the time markers in a pair of said stored event data packets and being operable to compare them and indicate a coincidence event if the difference between the two received time markers is within a preset time window; b) output register means connected to the comparator circuit for storing a coincidence data packet that includes an indication that a coincidence event has taken place and the location data for the two detector modules that produced the event data packets which are responsible for the coincidence event; c) clock means for dividing each sample period into a plurality of time increments; d) shift means connected to the clock means for changing the pair of stored event data packets coupled to the comparator circuits during each time increment, such that a plurality of pairs of event data packets are compared for coincidence events by the comparator circuit during each sample period; and image reconstruction means connected to the coincidence detector circuit for receiving the coincidence data packets therefrom and reconstructing an image.
Claim 2
Dependent Claim
264 words
A positron emission tomographic scanner which comprises: detector means having a plurality of detector modules which produce a corresponding plurality of event data packets during a sample period, each event data packet indicating the location of the detector module which produced it and including a time marker indicative of the time at which a scintillation event was detected by the detector module; a coincidence detector circuit connected to receive and store the plurality of event data packets produced during each sample period, the coincidence detector circuit including: a) a comparator circuit coupled to receive the time markers in a pair of said stored event data packets and being operable to compare them and indicate a coincidence event if the difference between the two received time markers is within a preset time window; b) output register means connected to the comparator circuit for storing a coincidence data packet that includes an indication that a coincidence event has taken place and the location data for the two detector modules that produced the event data packets which are responsible for the coincidence event; c) clock means for dividing each sample period into a plurality of time increments; d) shift means connected to the clock means for changing the pair of stored event data packets coupled to the comparator circuits during each time increment, such that a plurality of pairs of event data packets are compared for coincidence events by the comparator circuit during each sample period; and image reconstruction means connected to the coincidence detector circuit for receiving the coincidence data packets therefrom and reconstructing an image.
Claim 3
Dependent Claim
51 words
The positron emission tomographic scanner as recited in claim 1 in which the coincidence detector circuit includes a plurality of comparator circuits and the shift means changes the pairs of stored event data packets coupled to each of said plurality of comparator circuits a plurality of times during each sample period.
Claim 4
Dependent Claim
103 words
The positron emission tomographic scanner as recited in claim 1 in which the shift means includes a set of cascade connected row holding registers, which each store respective ones of the event data packets, and a set of cascade connected column holding registers, which each store other respective ones of the event data packets, and one of the row holding registers and one of the column holding registers are coupled to the comparator circuit, wherein the location of the event data packets stored in the row holding registers and the column holding registers are changed during each time increment of the sample period.
Claim 5
Dependent Claim
44 words
The positron emission tomographic scanner as recited in claim 3 in which the coincidence detector circuit includes a plurality of comparator circuits, each of said comparator circuits being connected to respective ones of the row holding registers and to said one column holding register.
Claim 6
Dependent Claim
30 words
The positron emission tomographic scanner as recited in claim 4 which includes a plurality of output register means, each connected to a respective one of said plurality of comparator circuits.
Claim 7
Dependent Claim
39 words
The positron emission tomographic scanner as recited in claim 5 in which the plurality of output registers are cascade connected and the location of coincidence data packets stored therein are changed during each time increment of the sample period.
Claim 8
Dependent Claim
38 words
The positron emission tomographic scanner as recited in claim 4 in which the coincidence detector circuit includes means responsive to a transaxial field of view mask to control the number of comparator circuits operable during each time increment.
Claim 9
Dependent Claim
36 words
The positron emission tomographic scanner as recited in claim 7 in which the transaxial field of view of the coincidence detector circuit may be changed by changing the data in the transaxial field of view mask.
Claim 10
Dependent Claim
46 words
The positron emission tomographic scanner as recited in claim 1 in which the coincidence detector circuit includes a window register which stores said preset time window, and the value of said preset time window may be changed by storing a different value in said window register.
Claim 11
Dependent Claim
70 words
The positron emission tomographic scanner as recited in claim 1 in which the detector modules are disposed in a ring around a central axis, the event data packets each include axial position data, and the comparator circuit includes axial angle filter means which inhibit the indication of said coincidence event if the difference between the axial position data in the two event data packets being compared exceed a preset amount.
Claim 12
Dependent Claim
44 words
The positron emission tomographic scanner as recited in claim 10 in which the coincidence detector circuit includes an angle register which stores said preset amount, and the value of said preset amount may be changed by storing a different value in said angle register.
Claim 13
Dependent Claim
67 words
The positron emission tomographic scanner as recited in claim 1 in which the comparator circuit includes means for adding an offset to one of the time markers in each pair of stored event data packets and means for comparing the resulting pair of time markers and indicating a random coincidence event if the difference between these resulting pair of time markers is within a preset time window.
Claim 14
Dependent Claim
30 words
The positron emission tomographic scanner as recited in claim 12 in which the coincidence data packet stored by the output register means indicates when a random coincidence event is detected.
Claim 15
Dependent Claim
53 words
The positron emission tomographic scanner as recited in claim 1 in which the comparator circuit includes means responsive to a calibration mode signal for outputting said difference between the two received time markers, and the coincidence data packet stored by the output register means indicates said difference between the two received time markers.
References Cited (Backward Citations)
US4284890A
Cited
US4983841A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1996-08-30 | 1997-03-01 | 1997-08-31 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2000-08-30 | 2001-03-01 | 2001-08-31 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2004-08-30 | 2005-03-01 | 2005-08-31 | $7700.00 | Window Closed / Lapsed |