Semiconductor gamma-ray camera and medical imaging system

• US 5,847,396 A
• Filed: 07/03/1997
• Issued: 12/08/1998
• Est. Priority Date: 12/23/1994
• Status: Expired due to Term

• Current Assignee: Digirad Corporation
• Original Assignee: Digirad Corporation
• Inventors: Doty, F. Patrick, Lingren, Clinton L., Apotovsky, Boris, Friesenhahn, Stanley J., Augustine, Frank L., Ashburn, William L., Butler, Jack F.
• Primary Examiner(s): Porta, David P.
• Assistant Examiner(s): Bruce, David Vernon
• Application Number:
  US08/887,960
• Time in Patent Office: 523 Days
• Field of Search: 250/369, 250/371, 250/366
• US Class Current: 250/369
• CPC Class Codes: A61B 6/037 Emission tomography
• CPC Class Codes: A61B 6/4258 for detecting non x-ray radiation, e.g. gamma radiation A61B6/037 takes precedence
• CPC Class Codes: G01T 1/161 Applications in the field of nuclear medicine, e.g. in vivo counting apparatus for radiation diagnosis A61B6/00
• CPC Class Codes: G01T 1/1642 using a scintillation crystal and position sensing photodetector arrays, e.g. ANGER cameras
• CPC Class Codes: G01T 1/243 Modular detectors, e.g. arrays formed from self contained units constructional or manufacturing details H01L25/00
• CPC Class Codes: G01T 1/247 Detector read-out circuitry for processing gain or off-set correction H04N
• CPC Class Codes: H01L 27/146 Imager structures
• CPC Class Codes: H01L 27/14658 X-ray, gamma-ray or corpuscular radiation imagers measuring X-, gamma- or corpuscular radiation G01T1/00
• CPC Class Codes: H01L 27/14676 X-ray, gamma-ray or corpuscular radiation imagers measuring X-, gamma- or corpuscular radiation G01T1/00
• CPC Class Codes: H04N 5/32 Transforming X-rays cameras or camera modules for generating image signals from X-rays H04N23/30; circuitry of SSIS for transforming X-rays into image signals H04N25/30

Abstract

A high-energy photon imaging system including an imaging head, a signal processor, a data acquisition system and an image processing computer. The imaging head includes a detector comprising a plurality of closely-packed detection modules. Each detection module comprises a plurality of detection elements mounted to a circuit carrier. The detection elements produce electrical pulses having amplitudes indicative of the magnitude of radiation absorbed by the detection elements. The circuit carrier includes channels for conditioning and processing the signals generated by corresponding detection elements and for preparing the processed signals for further processing by a signal processor. Each conditioning and processing channel stores the amplitudes of the detection element electrical pulses exceeding a predetermined threshold. The detection modules employ a fall-through circuit which automatically finds only those detection elements that have a stored pulse amplitude exceeding the threshold. The fall-through circuit searches for the next detection element and associated channel having a valid event. The signal processor performs diagnostics, gain normalization, and response efficiency normalization functions. The data acquisition system controls the acquisition and processing of data received from the conditioning and processing channels, produces image data based upon the data in a format that is compatible with existing imaging cameras, and transmits the data to the image processing computer. The image processing computer formulates images based upon the processed signals and displays the formulated images on a display device.

Claims

1. A fall-through event system for selecting events generated by a plurality of signal conditioning and processing channels, each channel coupled to a corresponding detection element, each channel conditioning and processing electrical pulses produced by the corresponding detection element, and each channel producing a valid event whenever the corresponding detection element produces a pulse exceeding a predetermined threshold, comprising:

a. means for scanning the channels, wherein the scanning means scans each channel in a predetermined sequence until finding a valid event, and, upon finding a valid event, enables the channel containing the valid event and awaits receipt of an advance signal before continuing to scan subsequent channels in the sequence.

2. The fall-through event system of claim 1, wherein each channel independently conditions and processes the electrical pulses produced by the corresponding detection element.

3. The fall-through event system of claim 1, wherein each channel receives the electrical pulses produced by the corresponding detection element at random times.

4. The fall-through event system of claim 1, wherein each channel produces a valid event based upon the amplitude of the electrical pulses produced by the corresponding detection element.

5. The fall-through event system of claim 1, wherein each channel stores the amplitude of the electrical pulses which exceed a predetermined threshold.

6. The fall-through event system of claim 5, wherein the channel enabled by the reading means generates a valid signal, outputs an address associated with the enabled channel, and outputs the amplitude stored by the enabled channel.

7. The fall-through event system of claim 6, wherein, upon receipt of the advance signal, the enabled channel ceases to output the valid signal, the associated address, and the amplitude, and wherein the enabled channel resets the amplitude stored by the enabled channel.

8. The fall-through event system of claim 6, wherein the enabled channel generates a digital representation of the amplitude stored by the enabled channel.