Koninklijke Philips Corporation N.v.

Marconi Medical Systems, Inc.

Barry D Kline

Jerome John Griesmer

A subject ( ) is disposed adjacent a detector array ( ) for the purposes of nuclear imaging. The subject ( ) is injected with a radioactive isotope ( ) and &ggr;-ray emissions indicative of nuclear decay are detected at the detector array ( ). P-ASIC ( ) preamplifier circuits are complex low-noise integrated circuits which dissipate a considerable amount of power (300-500 mW each). These components account for most of the dissipated power on the daughter cards ( ). In order to facilitate the cooling of these electrical components, they are mounted on circuit boards ( ) that are arranged parallel to each other extending perpendicularly away from the detector array ( ). This provides channels between the boards through which cooling air is drawn by an array of fans ( ).

Method of cooling high density electronics

A subject ( ) is disposed adjacent a detector array ( ) for the purposes of nuclear imaging. The subject ( ) is injected with a radioactive isotope ( ) and &ggr;-ray emissions indicative of nuclear decay are detected at the detector array ( ) these signals are processed and reconstructed into an image representation of the anatomy of the subject ( ). A dual level arbitration system orders detected signals for ease of processing and efficiency of reconstruction. The first level of the arbiter monitors a group of individual detectors ( ). It locks out any signal that arrives from its group of detectors if a previous signal is still being analyzed. This avoids paralyzation of the system. The second level of the arbiter consists of a plurality of memories, one for each group of individual detectors ( ) that store an address and energy of each processed signal. These memories pass a token around among themselves, and if they possess the token, as well as data, they load that data onto a data collection bus, which transfers it to an event archive ( ) for storage until enough data is collected to be reconstructed into an image of the subject ( ).

Data reduction architecture for nuclear medicine imagers

A subject ( ) is disposed adjacent a detector array ( ). The subject ( ) is injected with a radioactive isotope ( ) and &ggr;-ray emissions indicative of nuclear decay are detected at the detector array ( ). The detector array generates electrical signals in response to each &ggr;-ray which signals are processed ( ) and reconstructed ( ) into an image representation of the anatomy of the subject ( ). A high voltage bias is applied across the detector array. The bias is applied by a set of bias strips ( ) and an electrically isolated common busbar ( ) built onto a sheet of flexible circuit material. This flexible circuit ( ) is highly transmissive to gamma radiation in the energy range 60-180 keV which is typically used in diagnostic nuclear medicine. Connections between the common busbar ( ) and the bias strips ( ) are made by resistors ( ) on individual detector cards. Each bias strip is capacitively coupled ( ) to the local ground on each detector card to form a Faraday shield around each detector array. Bias strips set above groups of detector arrays and electrical pads ( ) are disposed along opposite faces. A substantially uniform DC electric field is set up between the strips and pads across the detector array. The strips and pads substantially surround groups of arrays defining Faraday cages. Capacitive filters ( ) connected with the strips filter out noise. The capacitor's connection to the P-ASIC ground completes a Faraday shield around the highly sensitive detector array ( ). Resistors ( ) electrically isolate each of the Faraday cages. Additionally, light baffles are added to prevent visible light from generating a signal in the detector array ( ). Collimator vanes ( ) are supported on a ground layer ( ) which is separated from the conductive strips ( ) by a resilient foam layer ( ).

High voltage distribution system for CZT arrays

A subject ( ) is disposed adjacent a detector array ( ) of a nuclear camera. The subject ( ) is injected with a radioactive isotope ( ) and &ggr;-ray emissions indicative of nuclear decay are detected at the detector array ( ). Individual detectors ( ) are monitored in groups of 64. When one of them detects a nuclear event, it produces an electrical spike that is filtered into a Gaussian with about a 1.2 &mgr;sec peaking time. A 10 bit analog to digital converter ( ) 10 repeatedly digitizes the amplitude of the Gaussian pulse, e.g. at a 20 MHz clock rate. The 10 bit digitized pulse amplitudes are monitored by a 10 bit comparitor ( ), which monitors consecutive values of the digitized signal, looking for the peak value, e.g. for the amplitude to stop rising. When the peak is detected, the most recent four digital pulse amplitudes contiguous to the peak are summed in a 12 bit accumulator ( ) to generate a 12 bit peak amplitude value. A series of 12-bit peak values and the corresponding pixel addresses are stored in a buffer memory of the event analyzer ( ). A reconstruction processor ( ) reconstructs the identifications of the &ggr;-ray receiving detectors, or other indicators of event detection location, and the digital peak values to generate an image representation.

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Cleveland Hts., OH, United States of America

Barry D Kline