Radiant energy – Invisible radiant energy responsive electric signalling – Semiconductor system
Reexamination Certificate
2000-11-24
2003-07-01
Porta, David (Department: 2878)
Radiant energy
Invisible radiant energy responsive electric signalling
Semiconductor system
C250S370090, C250S370130
Reexamination Certificate
active
06586744
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention deals with the diagnostic imaging arts. It finds particular application in conjunction with electronics used in nuclear cameras and will be described with particular reference thereto. However, it is to be appreciated that the present invention has application in other devices that have electronics that require cooling and is not limited to the aforementioned application.
Nuclear imaging employs a source of radioactivity togs image the anatomy of a subject. Typically, a radiopharmaceutical is injected into the patient. This radiopharmaceutical contains atoms that decay at a predictable rate. Each time an atom decays, it releases a &ggr;-ray. These &ggr;-rays are detected, and from information such as their detected position and energy, a representation of the interior of the subject is reconstructed.
Typically, a nuclear camera has one, two, or three detector heads. Each head has a large scintillator sheet, such as doped sodium iodide, which converts incident radiation into flashes of light. An array of photomultiplier tubes is disposed in back of the scintillator to monitor for light flashes. The output of the photomultiplier tubes and associated circuitry indicates the coordinates of each scintillation on the sodium iodide crystal and its energy. Unfortunately, there are numerous non-uniformities and inaccuracies when using a large scintillator crystal and an array of photomultiplier tubes.
Rather than using a single, large scintillator and photomultiplier tubes, others have proposed using an array of small scintillators, each associated with a photodiode or other photoelectrical device which senses a scintillation in each individual scintillation crystal. Other types of individual solid-state detectors have also been suggested.
For resolution on the order of a millimeter, each scintillator/photodiode or other detector element is typically on the order of a millimeter square. Each of the detector elements needs to be powered and to have its output electrical signals processed. Typically, the powering and at least a portion of the processing circuitry is mounted in close association with the individual detectors. This leads to a high density of electrical components, many of which generate significant heat. Cooling the electronics becomes a significant problem.
The present invention provides a new and improved method and apparatus that overcomes the above referenced problems and others.
SUMMARY OF THE INVENTION
In accordance with one aspect of the present invention, a nuclear imaging apparatus is given. An array of detectors detects &ggr;-rays, information about the &ggr;-rays are processed by electronics, a cooling system cools the electronics, and a reconstruction processor converts the &ggr;-ray information into an image representation.
According to a more limited aspect of the present invention, the detector is an array of cadmium-zinc-telluride crystals.
According to a more limited aspect of the present invention, the detectors are collimated in one dimension.
According to a more limited aspect of the present invention, the cooling system includes fans and a cooling region.
According to a more limited aspect of the present invention, L-shaped connectors allow heat producing circuit boards to be disposed such that their disposition facilitates cooling.
According to a more limited aspect of the present invention, event analyzers detect events, their strength, and their locations, and sends this information to be stored in an event archive.
According to another aspect of the present invention, a nuclear camera is given. A detector head includes a housing within which are an array of detectors, circuit boards defining air channels, and heat generating P-ASICs mounted on the circuit boards.
According to a more limited aspect of the present invention, the circuit boards are mounted back to back in pairs.
According to another aspect of the present invention, a method of nuclear imaging is given. A subject is injected with a radiopharmaceutical that emits &ggr;-rays. The &ggr;-rays are detected by electronics and reconstructed into an image representation. The electronics are arranged to facilitate their cooling and they are cooled.
According to another aspect of the present invention, a method of nuclear imaging is given. &ggr;-rays are detected by an array of detector arrays. The array is mounted on heat generating circuitry and air is passed along the circuitry to cool it. Signals are processed from the detector array and converted into an image representation.
According to a more limited aspect of the present invention, the detector array is biased by high-voltage circuitry on the board. The signals from the detector array are pre-amplified by P-ASICs on the circuit boards.
One advantage of the present invention is that it keeps electrical components at safe temperature levels.
Another advantage of the present invention is that it allows for a large number of detectors in a small area.
Another advantage of the present invention resides in high sensitivity and detailed spatial sampling resolution.
Yet another advantage of the present invention is that it avoids the use of liquid coolant or cryogenic cooling.
Still further benefits and advantages of the present invention will become apparent to those skilled in the art upon a reading and understanding of the preferred embodiments.
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Griesmer Jerome J.
Kline Barry D.
Lee Shun
Marconi Medical Systems, Inc.
Porta David
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