Signal enhancement module

• US 7,164,130 B2
• Filed: 02/18/2004
• Issued: 01/16/2007
• Est. Priority Date: 02/18/2003
• Status: Active Grant

• Current Assignee: Digirad Health, Inc. (Star Equity Holdings, Inc.)
• Original Assignee: Digirad Corporation
• Inventors: Welsh, Dan, Kindem, Joel, Conwell, Richard L., Gurley, Michael
• Primary Examiner(s): Porta; David
• Assistant Examiner(s): BOOSALIS, FANI POLYZOS
• Application Number:
  US10/782,730
• Publication Number:
  US 20040173750A1
• Time in Patent Office: 1,063 Days
• Field of Search: 250/336.41, 250/363.01, 250/363.02, 250/363.03, 250/363.07, 250/363.09, 250/370.01, 250/370.07, 250/370.08, 250/370.09, 250/336.1
• US Class Current: 250/336.1
• CPC Class Codes: G01T 1/1647 Processing of scintigraphic data not related to a particular imaging system G01T1/2992

Abstract

Events of interest are detected within a gamma ray detection system. Characteristics of undesired signals, including a multiplicity of events within the signal, a density of events within the signal, and other aspects are determined. The signal is filtered based on its expected characteristics. A signal which does not have the expected characteristics is rejected, and an image is formed that excludes those rejected signals.

Claims

1. A method, comprising:

storing a signal indicative of a detection over a specified length of time by an electromagnetic detector in a buffer;

comparing said signal to at least one criterion, said at least one criterion representing a characteristic of a signal, said characteristic indicative of whether the signal resulted from detection of a desired electromagnetic wave as being rejected and indicating a signal when said comparing indicates that the signal did not result from detection of the desired electromagnetic wave, wherein said comparing comprises determining a multiplicity of events within the signal in the buffer, and rejecting the signal if the number of events is outside a specified threshold.

2. A method as in claim 1, wherein said signal is indicative of a gamma ray detection by a gamma ray detector.

3. A method as in claim 2, wherein said criterion includes a threshold based on expected amounts of gamma ray detection during a specified procedure.

4. A method as in claim 3, wherein said comparing comprises using a raw multiplicity filter, to reject signals when they do not have more than a specified number of events within a specified time.

5. A method as in claim 3, wherein said comparing comprises using a global density filter to reject signals when they do not have more than a specified number of events in a specified time period.

6. A method as in claim 3, wherein said comparing comprises using a local density filter to reject strings in a signal that have more than a specified number of events in a specified time.

7. A method as in claim 3, wherein said comparing comprises using a raw multiplicity filter to reject signals when they have a size greater than a specified amount.

8. A method as in claim 3, wherein said comparing comprises using an average energy filter that rejects signals based on a comparison to a specified average energy threshold.

9. A method as in claim 2, wherein said comparing comprises comparing the signal to a criterion that represents vibrational energy.

10. A method as in claim 2, wherein said comparing comprises comparing the signal to a criterion that represents a cosmic ray.

11. A method as in claim 2, wherein said comparison comprises comparing the signal to a plurality of criterion that represent both vibrational energy and a cosmic ray.

12. A method as in claim 1, wherein said storing a signal comprises storing the signal in a buffer along with an associated signal that represents whether the signal is complete.

13. A method as in claim 1, further comprising forming an image and excluding rejected signals from said image.

14. A method as in claim 1, further comprising initially associating a second signal representing a valid signal with the signal, and using said comparing to change said second signal to a value representing an invalid signal when said comparing indicates that the signal did not result from detection of the desired electromagnetic wave.

15. A method as in claim 14, wherein said second signal is a digital bit.

16. A method, comprising:

obtaining a first signal from an electromagnetic detector, indicative of a detection by the electromagnetic detector;

associating a second signal with the first signal, the second signal having a first value which indicates that the first signal is valid;

processing the value of the first signal, to determine whether the first signal represents a desired event being monitored; and

changing the second signal to a second value when said processing indicates that the electromagnetic detector signal represents an event other than a desired observed event, wherein said processing comprises comparing the signal to a criterion that represents vibrational energy, and changing the value of the second signal to represent an invalid signal when said comparing indicates that the signal represents vibrational energy.

17. A method, comprising:

obtaining a first signal from an electromagnetic detector, indicative of a detection by the electromagnetic detector;

associating a second signal with the first signal, the second signal having a first value which indicates that the first signal is valid;

processing the value of the first signal, to determine whether the first signal represents a desired event being monitored; and

changing the second signal to a second value when said processing indicates that the electromagnetic detector signal represents an event other than a desired observed event, wherein said processing comprises comparing the signal to a criterion that represents a cosmic ray, and changing the value of the second signal to represent an invalid associated first signal, when said comparing detects that the signal represents a cosmic ray.

18. A system comprising:

an electromagnetic detector, having a surface adapted to detect an electromagnetic wave, and producing an output signal indicative of a detection;

a buffer, which stores a length of said output signal over a specified length of time; and

a signal processor, including an electronic filter therein, which processes said output signal in said buffer, using a filter characteristic which represents a multiplicity of events within the signal and that indicates whether the output signal resulted from detection of a desired electromagnetic phenomenon, and indicating signals as being rejected when they did not result from said detection of said desired electromagnetic phenomenon.

19. A system as in claim 18, wherein said electromagnetic detector is a medical gamma ray detector.

20. A system as in claim 19, further comprising an image display which displays an image based on said output signal, including only signals that resulted from detection of the desired electromagnetic phenomenon.

21. A system as in claim 19, wherein said filter characteristic represents a characteristic of incoming cosmic rays.

22. A system as in claim 19, wherein said filter characteristic represents a characteristic of electromagnetic interference.

23. A system as in claim 19, wherein said filter characteristic represents a characteristic of mechanical vibration.

24. A system as in claim 18, wherein said filter characteristic represents a density of events within the signal.

25. A system as in claim 18, wherein said signal processor includes a buffer therein which stores an electronic representation of said output signal, and stores a status signal indicative of whether the output signal is rejected.

26. A signal processor, comprising:

an input portion, receiving a signal from a medical gamma ray detector;

a buffer, which stores a length of said output signal over a specified length of time;

a signal processor portion, including an electronic filter therein which processes said signal in said buffer to reject portions of the signal based on a number of events within the signal that did not result from detection of a desired electromagnetic phenomenon, and produces an image output signal, representing an image based on at least one signal from said image portion which is not rejected by said signal processor portion.

27. A signal processor as in claim 26, wherein said electronic filter rejects signals based on a density of events within the signal.

28. A signal processor as in claim 26, wherein said electronic filter filters out signals which have a characteristic representing incoming cosmic rays.

29. A signal processor as in claim 26, wherein said electronic filter filters out signals which have a characteristic representing electromagnetic interference.

30. A signal processor as in claim 26, wherein said electronic filter filters out signals which have a characteristic representing mechanical vibration.

31. A method, comprising:

determining, in a medical gamma ray system, a dose and number of gamma ray signals which will be applied to a patient;

receiving gamma rays from the patient as applied by the medical camera ray system;

using said dose and number of gamma ray signals to form a filter to filter out portions of the received gamma rays

that are outside a range that is based on said dose and number of gamma ray signals determined in said determining.