Surgery – Diagnostic testing – Detecting nuclear – electromagnetic – or ultrasonic radiation
Reexamination Certificate
1997-05-30
2001-01-09
Kamm, William E. (Department: 3737)
Surgery
Diagnostic testing
Detecting nuclear, electromagnetic, or ultrasonic radiation
C250S363040, C250S363030, C600S425000
Reexamination Certificate
active
06171243
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to the art of diagnostic imaging. It finds particular application in conjunction with nuclear or gamma cameras and will be described with particular reference thereto. It is to be appreciated, however, that the present invention will also find application in other non-invasive investigation techniques and imaging systems such as single photon planar imaging, whole body nuclear scans, positron emission tomography (PET) and other diagnostic modes.
Positron emission tomography (PET) scanners are known as coincidence imaging devices. In planar coincidence imaging, two radiation detectors oppose each other with a subject disposed between the detectors. Typically, one or more radiopharmaceuticals or radioisotopes capable of generating positron emission radiation are injected into the subject. The radioisotope preferably travels to an organ of interest whose image is to be produced. The detectors scan the subject along a longitudinal axis without rotation producing a data set with incomplete angular sampling, otherwise known as limited angle tomography. Radiation events are detected on each detector and a coincidence circuitry compares and temporally matches the events on each detector. Events on one detector which have a coincident event on the other detector are treated as valid data and may be used in image reconstruction.
Typically, the detector includes a scintillation crystal that is viewed by an array of photomultiplier tubes. The relative outputs of the photomultiplier tubes are processed and corrected, as is conventional in the art, to generate an output signal indicative of (1) a position coordinate on the detector head at which each radiation event is received, and (2) an energy of each event. The energy is used to differentiate between various types of radiation such as multiple emission radiation sources and to eliminate noise, or stray and secondary emission radiation. A two-dimensional image representation is defined by the number of coincidence radiation events or counts received at each coordinate. However during a scan, only a fraction of the events detected are coincidence events. As such, scan times are increased in an effort to obtain a sufficient data sampling for image reconstruction which poses additional inconveniences to the subject and an increase in scanning costs from reduced patient throughput.
The present invention provides a new and improved diagnostic imaging system and method which provides diagnostic information in addition to coincidence events which overcomes the above-referenced problems and others.
SUMMARY OF THE INVENTION
In accordance with the present invention, a new and improved diagnostic imaging system and method for diagnostic imaging is provided. The diagnostic imaging system includes a gantry which defines an examination region that receives a subject where the subject includes a positron emitter and a single photon emitter. First and second radiation detectors are oppositely disposed on the gantry and have the examination region therebetween. The first and second radiation detectors detect radiation from the examination region. A coincidence circuit is connected to the first and second radiation detectors and determines coincidence radiation events emitted from the positron emitter. Coincidence data is generated based on the coincidence radiation events. A third radiation detector which includes a collimator, detects collimated radiation traveling along a selected projection path. The third radiation detector is supported on the gantry at an angle to the first and second radiation detectors. A projection data processor is connected to the third radiation detector and generates collimated projection data based on collimated radiation detected from the single photon emitter. A combiner selectively combines the coincidence data and the collimated projection data into an image volume and a reconstruction processor reconstructs an image representation from the image volume.
In a more limited aspect of the present invention, the diagnostic imaging system further includes a transmission radiation source which generates transmission radiation toward the examination region. The third radiation detector detects both the transmission radiation from the transmission radiation source and emission radiation from the subject. A sorter sorts the emission and transmission radiation detected. The projection data processor generates transmission projection data based on the transmission radiation detected and selectively combines the transmission projection data with the collimated projection data.
In accordance with another aspect of the present invention, a diagnostic imaging system is provided including a gantry which supports a plurality of radiation detectors which detect coincidence radiation emitted from a subject disposed in an examination region. A processor generates coincidence data from the detected coincidence radiation and a reconstruction processor reconstructs the coincidence data into an image representation of a selected portion of the subject. The diagnostic imaging system further includes a collimated radiation detector which detects collimated radiation from the examination region. A collimation data processor generates collimated radiation data based on the collimated radiation detected and the collimated radiation data is selectively combined with the coincidence data before reconstruction by the reconstruction processor.
One advantage of the present invention is that a positron imaging system which generates coincidence events is combined with a single photon imaging system.
Another advantage of the present invention is that image reconstruction is improved by combining coincidence data with collimated data.
Yet another advantage is that sufficient image quality may be obtained in a shorter scan time, thereby improving patient throughput and minimizing patient inconvenience. Still another advantage is that the production of whole body planar images with additional depth information, PET images with transmission attenuation, and combined PET/SPECT, dual isotope imaging is facilitated.
Still further advantages of the present invention will become apparent to those of ordinary skill in the art upon reading and understanding the following detailed description of the preferred embodiments.
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DiFilippo Frank P.
Gagnon Daniel
Fry John J.
Gurin Timothy B.
Kamm William E.
Mantis Mercader Eleni
Picker International Inc.
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