Noninvasive determination of alcohol in tissue

• US 20050261560A1
• Filed: 05/24/2004
• Published: 11/24/2005
• Est. Priority Date: 04/11/2001
• Status: Active Grant

• Current Assignee: John D. Maynard, Russell E. Abbink, Trent D. Ridder
• Original Assignee: TruTouch Technologies, Inc.
• Inventors: Maynard, John D., Abbink, Russell E., Ridder, Trent D.
• Granted Patent: US 7,403,804 B2
• Time in Patent Office: Days
• US Class Current: 600/310
• CPC Class Codes: A61B 5/0059 using light, e.g. diagnosis by transillumination, diascopy, fluorescence A61B5/0093, A61B5/1455, A61B5/02416 and A61B5/0261 take precedence
• CPC Class Codes: A61B 5/0075 by spectroscopy, i.e. measuring spectra, e.g. Raman spectroscopy, infrared absorption spectroscopy A61B5/0071 takes precedence
• CPC Class Codes: A61B 5/14546 for measuring analytes not otherwise provided for, e.g. ions, cytochromes
• CPC Class Codes: A61B 5/1455 using optical sensors, e.g. spectral photometrical oximeters

Abstract

An apparatus and method for non-invasive determination of attributes of human tissue by quantitative infrared spectroscopy. The system includes subsystems optimized to contend with the complexities of the tissue spectrum, high signal-to-noise ratio and photometric accuracy requirements, tissue sampling errors, calibration maintenance problems, and calibration transfer problems. The subsystems include an illumination subsystem, a tissue sampling subsystem, a spectrometer subsystem, a data acquisition subsystem, and a processing subsystem. The invention is applicable, as examples, to determining the concentration or change of concentration of alcohol in human tissue.

Claims

1. An apparatus for non-invasive determination of an attribute of human tissue by quantitative near infrared spectroscopy comprising:

an illumination subsystem;

a tissue sampling subsystem, in optical communication with the illumination subsystem;

a spectrometer subsystem in optical communication with the tissue sampling subsystem, said spectrometer subsystem including a spectrometer;

a data acquisition subsystem including a detector which receives an output from the spectrometer subsystem and converts said output to a communicable representation, said data acquisition subsystem including means for modifying said communicable representation and producing an analyzable representation thereof; and

a processing subsystem for receiving said analyzable representation and further including means for determining the attribute from said analyzable representation.

2. An apparatus according to claim 1, wherein the illumination subsystem comprises a source of light that is substantially spatially homogeneous and substantially angularly homogeneous.

3. An apparatus according to claim 1, wherein the illumination subsystem comprises a light homogenizer.

4. An apparatus according to claim 3, wherein the light homogenizer comprises a light pipe.

5. An apparatus according to claim 4, wherein the light pipe has a polygonal cross-section along a portion of its length.

6. An apparatus according to claim 4, wherein the light pipe has an axis along the direction of light travel therethrough, and wherein the axis describes a bend.

7. An apparatus according to claim 4, wherein the light pipe has a diffuse internal surface.

8. An apparatus according to claim 3, wherein the light homogenizer comprises a glass diffuser.

9. An apparatus according to claim 1, wherein the illumination subsystem comprises a filament light source and a light homogenizer.

10. An apparatus according to claim 9, wherein the filament source comprises a tungsten halogen lamp.

11. An apparatus according to claim 1, wherein the illumination subsystem comprises a source of light, and a chamber mounted with the source such that light from the source is collected by the chamber and directed to an output of the chamber.

12. An apparatus according to claim 1, wherein the tissue sampling subsystem comprises a first optical waveguide in optical communication with the illumination subsystem and adapted to communicate light to tissue, and a second optical waveguide in optical communication with the spectrometer and adapted to receive light from tissue.

13. An apparatus according to claim 1, wherein the illumination subsystem and sampling subsystem comprise a light source, a chamber mounted with the light source such that light from the source is collected by the chamber and directed to an output of the chamber, a first optical waveguide in optical communication with the output of the chamber and adapted to communicate light to tissue, and a second optical waveguide in optical communication with the spectrometer subsystem and adapted to receive light from tissue.

14. An apparatus according to claim 13, wherein the chamber comprises a reflective internal surface, and wherein a portion of the internal surface is diffusively reflective.

15. An apparatus according to claim 1, wherein the tissue sampling subsystem comprises three rows of optical fibers, with two outer rows mounted on either side of an inner row, and wherein the outer rows are in optical communication with the illumination subsystem, and wherein the inner row is in optical communication with the spectrometer subsystem.

16. An apparatus according to claim 15, wherein the edges of fibers in adjacent rows are not less than 75 microns apart.

17. An apparatus according to claim 1, wherein the tissue sampling subsystem comprises a plurality of illumination fibers in optical communication with the illumination subsystem, and a plurality of detection fibers in optical communication with the spectrometer subsystem, wherein the illumination fibers are disposed at an angle to the detection fibers.

18. An apparatus according to claim 17, wherein the illumination fibers are disposed at an angle between 20 degrees and 30 degrees from normal to the tissue surface, inclined toward the detection fibers, and wherein the detection fibers are disposed at an angle between 20 degrees and 30 degrees from normal to the tissue surface, inclined toward the illumination fibers, and wherein each illumination fiber is separated from the nearest detection fiber inclined toward the illumination fiber by at least 75 microns.

19. The apparatus of claim 1, wherein the spectrometer subsystem comprises a VCSEL.

20. The apparatus of claim 1, wherein the processing subsystem comprises a multivariate model relating spectroscopic information to tissue attribute.

21. The apparatus of claim 20, wherein the multivariate model uses information at more than three wavelengths, and wherein the tissue attribute comprises alcohol concentration state or change of state.

22. The apparatus of claim 20, wherein the multivariate model comprises in vivo tissue spectra and corresponding attribute values, and in vitro spectra and corresponding attribute values.

23. The apparatus of claim 20, wherein the multivariate model comprises in vivo tissue spectra and corresponding attribute values, and spectral information from interferants.

24. The apparatus of claim 1, wherein the tissue sampling subsystem comprises a positioning device mounted with the tissue of the subject.

25. The apparatus of claim 1, wherein the tissue sampling subsystem comprises an interface to tissue on a hand of a subject.

26. The apparatus of claim 1, wherein the tissue sampling subsystem comprises an interface to tissue on a fingertip of a subject.

27. The apparatus of claim 1, wherein the tissue sampling subsystem comprises a bracket mounted with a base which references an elbow of a subject'"'"'s arm disposed thereon.

28. The apparatus of claim 27, wherein the tissue sampling subsystem comprises an adjustable hand rest spaced longitudinally from the bracket along the base.

combination said subsystems provide a clinically relevant level of precision and accuracy.

30. An apparatus according to claim 1, wherein the tissue sampling subsystem comprises a plurality of optical fibers having a numerical aperture of about 0.22.

29. An apparatus for non-invasive determination of an attribute of human tissue by quantitative near infrared spectroscopy comprising:

an illumination subsystem;

a spectrometer subsystem in optical communication with the illumination subsystem, said spectrometer subsystem including a spectrometer;

a tissue sampling subsystem, in optical communication with the spectrometer subsystem;

a data acquisition subsystem including a detector which receives an output from the tissue sampling subsystem and converts said output to a communicable representation, said data acquisition subsystem including means for modifying said communicable representation and producing an analyzable representation thereof; and

a processing subsystem for receiving said analyzable representation and further including means for determining the attribute from said analyzable representation.

31. An apparatus according to claim 29, wherein the tissue sampling subsystem comprises a light homogenizer mounted such that light from the spectrometer subsystem is homogenized.