Radiant energy – Invisible radiant energy responsive electric signalling – With or including a luminophor
Utility Patent
1998-10-23
2001-01-02
Hannaher, Constantine (Department: 2878)
Radiant energy
Invisible radiant energy responsive electric signalling
With or including a luminophor
C250S366000, C250S363020
Utility Patent
active
06169285
ABSTRACT:
FIELD OF THE INVENTION
The present invention pertains to the field of nuclear medicine. More particularly, the present invention relates to a technique for increasing the effective field of view of a radiation detector in a nuclear medicine imaging system.
BACKGROUND OF THE INVENTION
In nuclear medicine, images of internal structures or functions of a patient's body are acquired by using one or more gamma cameras to detect radiation emitted by a radio pharmaceutical that has been injected into the body. A computer system controls the gamma cameras to acquire data and then processes the acquired data to generate images. Nuclear medicine imaging techniques include single photon emission computed tomography (SPECT) and positron emission tomography (PET). SPECT imaging is based on the detection of individual gamma rays emitted from the body, while PET imaging is based on the detection of gamma ray pairs resulting from electron-positron annihilations and emitted in coincidence with each other. Accordingly, PET imaging is sometimes referred to as coincidence imaging. Nuclear medicine imaging systems, which are sometimes referred to as gamma camera systems, include dedicated SPECT systems, dedicated PET systems, and systems having dual PET/SPECT capability. Gamma camera systems with dual PET/SPECT capability are available from ADAC Laboratories of Milpitas, Calif.
Gamma camera detectors typically include a number of photomultiplier tubes (PMTs), which provide electrical outputs in response to scintillation events occurring within a scintillation crystal. Electronic circuits process the outputs of the PMTs to determine the position of each scintillation event. The PMT size and arrangement are chosen so that the light from one scintillation event spreads into several PMTs, and the event is typically positioned by calculating the signal-weighted average PMT position of the PMTs located near the event; this process may be referred to as the “centroid” method.
While this method generally is sufficiently accurate over most of the detector area, one long-standing problem associated with this method is poor position sensitivity near the edge of the detector. This problem is caused, at least in part, by the fact that there are no PMTs to sample the light that would have spread beyond the edges of the detector. The result is a region of the detector around the edges of its field of view which is practically unusable, reducing the overall sensitivity to the detection of photons. In addition, for PET systems with multiple fixed detectors, the result may be an increase in the size of regions of missing data (“gaps”) between detectors. Image reconstruction can be complicated by these effects. Therefore, what is needed is a gamma camera system which overcomes these and other disadvantages of the prior art.
SUMMARY OF THE INVENTION
A method and apparatus are provided for detecting a radiation-induced event in a radiation detector using virtual detector elements. The radiation detector includes multiple real detector elements adapted to respond to radiation-induced events. At least one of the real detector elements responding to the event is identified. The event is mapped to at least one virtual detector element. Data representing a response of the real detector element(s) and data representing a response of the virtual detector element(s) are then used to represent the event.
In particular embodiments, the event may be a scintillation event, and the detector elements may be photomultiplier tubes (PMTs). The event may mapped to a particular virtual PMT based on the peak real PMT for the event. Data representing the response of a virtual detector element may be generated based on data representing the response of a corresponding one or more real detector element(s).
Other features of the present invention will be apparent from the accompanying drawings and from the detailed description which follows.
REFERENCES:
patent: 4071761 (1978-01-01), Horrocks
patent: 4181855 (1980-01-01), Horrocks
patent: 4418282 (1983-11-01), Horrocks
patent: 5296708 (1994-03-01), Moyers et al.
patent: 5444252 (1995-08-01), Hug et al.
patent: 5461232 (1995-10-01), McCandless et al.
patent: 5471061 (1995-11-01), Moyers et al.
patent: 5493120 (1996-02-01), Geagan
patent: 5552606 (1996-09-01), Jones et al.
patent: 5565684 (1996-10-01), Gullberg et al.
patent: 5585637 (1996-12-01), Bertelsen et al.
patent: 5608221 (1997-03-01), Bertelsen et al.
patent: 5646408 (1997-07-01), Goldberg et al.
patent: 5841833 (1998-11-01), Mazess et al.
patent: 5847398 (1998-12-01), Shahar et al.
James A. Sorenson, Ph.D., et al.,Physics in Nuclear Medicine,W.B. Saunders Company, 2nd Ed., Philadelphia, 1987, pp. 438-442.
Robert Anthony Dekemp, B.A.Sc., Attenuation Correction Positron Emission Tomography Single Photon Transmission Measurement, Sep. 1992, McMaster Univ., Hamilton (ON), 106 pgs.
Siu K. Yu and Claude Nahmias, Single Photon Transmission Measurements in Positron Tomography Using137Cs, 1995, McMaster Univ., Hamilton (ON), 29 pgs.
Karp, et al., Singles Transmission in Positron Emission Tomography Using137Cs, from 1995 IEEE Nuclear Science Symposium and Medical Imaging Conference record vol. 13, University of Pennylvania and UGM Medical Systems (Philadelphia, PA), pp. 1363-1367.
P. Nellemann, et al., Performance Characteristics of A Dual Head Spect Scanner With Pet Capability, From 1995 IEEE Nuclear Science Symposium conference record vol. 3, ADAC Laboratories and UGM Laboratory, pp. 1751-1755.
Karp, et al., Singles Transmission in Volume-Imaging Pet With A137Cs Source,Phys. Med. Biol.,vol. 40, 1995, pp. 929-944.
Bailey, et al., Ecart Art-A Continuously Rotating Pet Camera: Performance Characteristics, Initial Clinical Studies, And Installation Considerations In A Nuclear Medicine Department,European Journal of Nuclear Medicine,vol. 24, No. 1, Jan. 1997, London (UK) and Knoxville (TN), 10 pgs.
Robert A. De Kemp, et al., Attenuation Correction in Pet Using Single Photon Transmission Measurement,Med. Phys.,vol. 21, No. 6, Jun. 1994, pp. 771-778.
G. Muehllehner, et al., “Performance Parameters of a Positron Imaging Camera,” IEEE Transactions on Nuclear Science, vol. NS-23, Feb. 1976, pp. 528-537.
R.A. De Kemp, et al., Design and Performance of 3D Photon Transmission Measurement on a Positron Tomograph With Continuously Rotating Detectors, International Meeting on Fully Three-Dimensional Image Reconstruction in Radiology and Nuclear Medicine, 1995, Ottowa and Hamilton (ON), Knoxville (TN), pp. 51-54.
Gerd Muehllehner, Positron Camera with Extended Counting Rate Capability,Journal of Nuclear Medicine,vol. 15, No. 7, Jul. 1975, pp. 653-657.
Karp et al., Continuous-Slice Penn-Pet: A Positron Tomograph with Volume Imaging Capability,Journal of Nuclear Medicine,vol. 13, No. 5, May 1990, pp. 617-627.
R.J. Smith et al., “Singles Transmission Scans Performed Post-Injection for Quantitative Whole Body Pet Imaging,” 1996 IEEE Nuclear Science Symposium Conference Record, vol. 3, Nov. 1996, Philadelphia (PA), 7 pgs.
Karp, et al., Abstract No. 156 From proceedings of the 41st Annual Meeting, Scientific Papers, vol. 35, No. 5, Attenuation Correction in Pet Using A Singles Transmission Source, May 1994, Philadelphia (PA), p. 41P.
G. Muehllehner, et al., Abstract No. 284, From Proceedings of the 42nd Annual Meeting, Scientific Papers, Spect Scanner With Pet Coincidence Capability,Journal of Nuclear Medicine,Jun. 14, 1995, p. 70P.
Glenn F. Knoll, University of Michigan,Radiation Detection and Measurement,Second Edition, John Wiley & Sons, Inc., New York, 1979, pp. 120-129 and 597-598.
James K. O'Donell, M.D., “Nuclear Medicine Camera Improves Image Quality and Patient Throughput”,Advance for Administrators in Radiology,Aug. 1997, pp. 82-83.
Wong, W.H. et al., “A Scintillation Detector Signal Processing Technique with Active Pileup Prevention for Extending Scintillation Count Rates,”IEEE Nuclear Science Symposium and Medical Imaging Conference,Albuquerque, New Mexico, Nov. 9-15, 1997, 5 pages.
Abstract, Wong, W.H. et al., “An Ultra-High Count-Rate Pos
Petrillo Michael J.
Vaska Paul
ADAC Laboratories
Blakely , Sokoloff, Taylor & Zafman LLP
Gabor Otilia
Hannaher Constantine
LandOfFree
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