Systems and methods for determining a state of a patient

• US 10,667,727 B2
• Filed: 09/05/2008
• Issued: 06/02/2020
• Est. Priority Date: 09/05/2008
• Status: Active Grant

• Current Assignee: Varian Medical Systems Incorporated (Siemens AG)
• Original Assignee: Varian Medical Systems Incorporated (Siemens AG)
• Inventors: Mostafavi, Hassan, Povzner, Sergey
• Primary Examiner(s): Salmon, Katherine D
• Application Number:
  US12/205,512
• Publication Number:
  US 20100063419A1
• Time in Patent Office: 4,288 Days
• Field of Search: None
• CPC Class Codes: A61B 2090/364 Correlation of different images or relation of image positions in respect to the body
• CPC Class Codes: A61B 5/1135 by monitoring thoracic expansion
• CPC Class Codes: A61B 5/7285 for synchronising or triggering a physiological measurement or image acquisition with a physiological event or waveform, e.g. an ECG signal A61B6/5205, A61B6/541, A61B8/5207, A61B8/543 take precedence
• CPC Class Codes: A61B 6/5288 involving retrospective matching to a physiological signal
• CPC Class Codes: A61B 6/541 involving acquisition triggered by a physiological signal
• CPC Class Codes: A61B 90/36 Image-producing devices or illumination devices not otherwise provided for
• CPC Class Codes: A61B 90/361 Image-producing devices, e.g. surgical cameras
• CPC Class Codes: G06F 2218/10 by analysing the shape of a waveform, e.g. extracting parameters relating to peaks
• CPC Class Codes: G06T 2207/30004 Biomedical image processing
• CPC Class Codes: G06T 7/248 involving reference images or patches
• CPC Class Codes: G06V 2201/03 Recognition of patterns in medical or anatomical images
• CPC Class Codes: G16H 30/40 for processing medical images, e.g. editing
• CPC Class Codes: G16H 40/63 for local operation
• CPC Class Codes: G16H 40/67 for remote operation

Abstract

A method of monitoring a patient includes obtaining a first image of an object, obtaining a second image of the object, determining a level of similarity between the first and second images, obtaining a third image of the object, determining a level of similarity between the first and third images, analyzing a time series of values that includes the determined level of similarity between the first and second images and the determined level of similarity between the first and third images, and determining a state of the patient based at least on a result of the act of analyzing.

Claims

1. A method comprising:

digitally obtaining a first image of an object;

digitally obtaining a second image of the object;

digitally processing the first and second images to determine a first level of similarity between the first and second images, wherein the first level of similarity comprises a similarity value derived using a two-dimensional array of pixel values of the first image and a two-dimensional array of pixel values of the second image;

obtaining a third image of the object; and

digitally processing the first and third images to determine a second level of similarity between the first and third images, wherein the second level of similarity comprises a similarity value derived using the two-dimensional array of pixel values of the first image and a two-dimensional array of pixel values of the third image, the second level of similarity being different from the first level of similarity;

wherein the first level of similarity and the second level of similarity form a time series, the first level of similarity between the first and second images representing a first phase of a physiological cycle of a patient, the second level of similarity between the first and third images representing a second phase of the physiological cycle of the patient, the physiological cycle being a respiratory cycle;

wherein the method further comprises electronically processing the time series by a processing unit to analyze the time series, wherein the time series is analyzed to determine whether one or more pre-defined criteria are satisfied for detecting and/or characterizing motion, and wherein the act of electronically processing the time series comprises using the first level of similarity as the first phase of the physiological cycle; and

wherein the method further comprises;

determining a first time point t₁;

determining a second time point t₂; and

determining a period T that is between the first and second time points;

wherein the first image is obtained at a time that is a fraction of the period T after a detected peak point.

2. The method of claim 1, wherein the time series is electronically processed by the processing unit for determining whether there is a lack of motion by the patient.

3. The method of claim 2, wherein the time series is electronically processed by the processing unit for determining whether there is a lack of motion by the patient comprises determining a plurality of points within a duration in the time series that have values below a prescribed threshold.

4. The method of claim 3, wherein the duration is greater than a respiratory period of the patient.

5. The method of claim 1, wherein the time series is electronically processed by the processing unit for determining whether there is a lack of periodicity in a motion by the patient.

6. The method of claim 5, wherein the act of determining whether there is a lack of periodicity in a motion by the patient comprises determining whether the time series exhibits an irregular pattern.

7. The method of claim 1, wherein the time series is electronically processed by the processing unit for determining whether the patient has shifted in position.

8. The method of claim 7, wherein the act of determining whether the patient has shifted in position comprises determining a plurality of points within a duration in the time series that have values below a prescribed threshold.

9. The method of claim 1, wherein the time series is electronically processed by the processing unit for determining whether a motion of the object is related to breathing.

10. The method of claim 1, wherein the process further comprises generating a signal for providing an alarm that indicates the determined state of the patient.

11. The method of claim 1, further comprising detecting and/or characterizing motion without determining an actual position of the patient.

12. The method of claim 1, wherein the act of digitally processing the first and second images to determine the first level of similarity between the first and second images does not require a detection of a marker specifically designed to be detected by an imaging device.

13. The method of claim 1, wherein the act of digitally processing the first and second images to determine the first level of similarity between the first and second images does not require a performance of image recognition to identify the object in the second image.

14. The method of claim 1, wherein the patient does not have a marker that is specifically designed to be detected by an imaging device.

15. The method of claim 1, wherein the first and second images are obtained using a camera.

16. The method of claim 1, wherein the first and second images are obtained using a radiation machine.

17. The method of claim 1, wherein the object comprises at least a portion of a blanket.

18. The method of claim 1, wherein the object comprises at least a portion of the patient'"'"'s clothes.

19. The method of claim 1, wherein the object is a part of the patient.

20. The method of claim 1, wherein the first image is a subset of a first image frame.

21. The method of claim 20, wherein the second image is a subset of a second image frame, and wherein a position of the first image in the first image frame is the same as a position of the second image in the second image frame.

22. The method of claim 20, further comprising obtaining the first image frame, wherein the first image is obtained by:

determining a portion in the first image frame, wherein the portion of the first image frame contains an image of a portion of the object that was undergoing a relatively high motion when the first image frame was obtained; and

using the portion as the first image.

23. The method of claim 20, further comprising obtaining the first image frame, wherein the first image frame is obtained when the patient is at an end of an exhale motion.

24. The method of claim 20, further comprising obtaining the first image frame, wherein the first image frame is obtained when the patient is at an end of an inhale motion.

25. The method of claim 1, further comprising obtaining a new image for use as the first image when it is determined that the patient has shifted position.

26. The method of claim 1, wherein the act of electronically processing the time series comprises performing a spectral analysis.

27. The method of claim 26, wherein the spectral analysis is performed to detect position shift, lack of periodicity, or lack of motion.

28. The method of claim 1, wherein the similarity value of the first level of similarity comprises a correlation value determined by performing a correlation between the first and second images.

29. The method of claim 1, wherein the similarity value of the first level of similarity indicates a degree of two-dimensional similarity between the first and second images.