Methods and apparatus for a remote, noninvasive technique to detect core body temperature in a subject via thermal imaging

• US 20040254472A1
• Filed: 05/25/2004
• Published: 12/16/2004
• Est. Priority Date: 05/27/2003
• Status: Active Grant

• Current Assignee: Cardiowave Incorporated
• Original Assignee: Cardiowave Incorporated
• Inventors: McQuilkin, Gary L.
• Granted Patent: US 7,340,293 B2
• Time in Patent Office: Days
• US Class Current: 600/473
• CPC Class Codes: A61B 5/015 By temperature mapping of body part
• CPC Class Codes: G01J 2005/0077 Imaging
• CPC Class Codes: G01J 5/0025 Living bodies ear thermometers G01J5/0011; detecting, measuring or recording for diagnostic purposes A61B5/00
• CPC Class Codes: G01J 5/53 Reference sources, e.g. standard lamps; Black bodies

Abstract

An approach to noninvasively, remotely and accurately detect core body temperature in a warm-blooded subject, human or animal, via thermal imaging. Preferred features such as the use of in-frame temperature references, specific anatomical target regions and a physiological heat transfer model help the present invention to overcome pitfalls inherent with existing thermal imaging techniques applied to physiological screening applications. This invention provides the ability to noninvasively, remotely and rapidly screen for diseases or conditions that are characterized by changes in core body temperature. One human application of this invention is the remote screening for severe acute respiratory syndrome (SARS), since fever is a common, early symptom. Other diseases and conditions that affect the core body temperature of humans or animals may also be noninvasively and remotely detected with this invention.

Claims

1. A thermal imaging system that provides core body temperature information of a subject, comprising

a thermal imaging device that acquires thermal image data of at least a portion of the subject when the subject is within a field of view of the device;

and

program instructions that derive a core body temperature information for the subject using the thermal image data.

2. The thermal imaging system of claim 1, further comprising program instructions to identify a portion of the thermal image data that corresponds to a target area of the subject.

3. The thermal imaging system of claim 2, wherein the target area is an eye region of the subject.

4. The thermal imaging system of claim 2, wherein the target area is a forehead region of the subject.

5. The thermal imaging system of claim 1, further comprising an in-frame temperature reference system positioned in the field of view of the device when the thermal image of the subject is acquired.

6. The thermal imaging system of claim 5, further comprising program instructions to calibrate the thermal image data using temperature data associated with the in-frame temperature reference system.

7. The thermal imaging system of claim 6, wherein the temperature reference system comprises a first temperature sensor providing ambient temperature information, a second temperature sensor that provides second temperature information, and a third temperature sensor that provides third temperature information.

8. The thermal imaging system of claim 6, wherein the calibration program instructions comprise a linear calibration algorithm to convert a measured temperature to a calibrated temperature.

9. The thermal imaging system of claim 7, wherein the calibration program instructions comprising a linear calibration algorithm to convert a measured temperature to a calibrated temperature.

10. The thermal imaging system of claim 1, further comprising program instructions comprising steps that convert a measured temperature to a corrected temperature based upon an emissivity characteristic of a surface.

11. The thermal imaging system of claim 2, further comprising program instructions that derive a core body temperature from data corresponding to the target area.

12. A method of remotely determining a core body temperature of a subject, comprising:

acquiring thermal image data for at least a portion of the subject; and

deriving the core body temperature of the subject using the thermal image data.

13. The method of claim 12, wherein said deriving step comprises using a portion of the thermal image data that corresponds to a target area of the subject to derive the core body temperature.

14. The method of claim 13, wherein the target area is an eye region of the subject.

15. The method of claim 13, wherein the target area is a forehead region of the subject.

16. The method of claim 12, further comprising using an in-frame temperature reference system positioned in the field of view of the device when the thermal image data of the subject is acquired.

17. The method of claim 16, further comprising calibrating the thermal image data using temperature data associated with the in-frame temperature reference system.

18. The method of claim 16, wherein the temperature reference system comprises a first temperature sensor providing ambient temperature information, a second temperature sensor that provides second temperature information, and a third temperature sensor that provides third temperature information.

19. The method of claim 17, wherein the calibrating step comprises using a linear calibration algorithm to convert a measured temperature to a calibrated temperature.

20. The method of claim 18, wherein the calibrating step comprises using a linear calibration algorithm to convert a measured temperature to a calibrated temperature.

21. The method of claim 12, wherein the deriving step comprises converting a measured temperature to a corrected temperature based upon an emissivity characteristic of a surface.

22. The method of claim 17, wherein the in-frame temperature reference system includes first and second elevated temperature references, the first elevated temperature reference being at a temperature higher than an expected value of the body surface temperature of the subject and the second elevated temperature reference being at a temperature lower than an expected value of the body surface temperature of the subject.

23. A method of screening for SARS, comprising:

acquiring thermal image data of at least a portion of a subject;

determining a core body temperature of the subject based on the thermal image data; and

using the determined core body temperature to assess whether the subject may have SARS.

24. A method of screening for a health condition, comprising

acquiring a thermal image of at least a portion of a subject;

determining a core body temperature of the subject based on the thermal image data; and

using the determined core body temperature to assess whether the subject may have a health condition.

25. The method of claim 24, wherein the health condition is selected from at least one of

a) SARS;

b) smallpox;

c) a health condition associated with bio-terrorism;

d) heat stroke;

e) hypothermia;

f) chronic wasting disease;

g) mad cow disease;

h) scrapies; and

i) West Nile Virus.

26. The method of claim 24, wherein the health condition is smallpox.

27. The method of claim 24, wherein the health condition is associated with bio-terrorism.

28. The method of claim 24, wherein the health condition is selected from heat-stroke and hypothermia.

29. The method of claim 24, wherein the health condition is selected from chronic wasting disease, mad cow disease, and scrapies.

30. The method of claim 24, wherein the health condition is West Nile virus.

31. A method of determining a core body temperature of a subject, comprising the steps of:

acquiring thermal image data of an eye region of the target subject; and

determining a core body temperature of the subject based on thermal image data associated with the eye region.

32. A method of determining a core body temperature of a subject, comprising the steps of:

acquiring thermal image data of a forehead region of the target subject; and

determining a core body temperature of the subject based on thermal image data associated with the forehead region.

33. A method of screening a target body for an abnormal core body temperature, comprising:

deriving at least one surface temperature of the target body remotely; and

determining a core body temperature of the target from the at least one surface temperature of the target body.

34. A method of determining a core body temperature of a target body, comprising:

simultaneously acquiring thermal image data of a subject and a surface associated with an ambient temperature; and

deriving the core body temperature of the target body from the simultaneously acquired surface and ambient temperature thermal image data.

35. A method of detecting a core body temperature of an animal, comprising the steps of:

determining a core body temperature of the animal using thermal image data; and

evaluating a health condition of the animal based on the determined core body temperature.

36. A thermal imaging system comprising an in-frame temperature reference system, said reference system comprising:

a first temperature reference surface having a relatively high emissivity; and

a second temperature reference surface having a relatively low emissivity.

37. The thermal imaging system of claim 36, further comprising a heater element coupled to both the first and second temperature reference surfaces.

38. The thermal imaging system of claim 36, wherein the in-frame temperature reference system further comprises an ambient temperature reference.