Method and means for measurement of biochemical components

• US 5,632,273 A
• Filed: 07/05/1994
• Issued: 05/27/1997
• Est. Priority Date: 02/04/1994
• Status: Expired due to Fees

• Current Assignee: Hamamatsu Photonics KK
• Original Assignee: Hamamatsu Photonics KK
• Inventors: Suzuki, Susumu
• Primary Examiner(s): Sykes, Angela D.
• Assistant Examiner(s): WINAKUR, ERIC FRANK
• Application Number:
  US08/270,986
• Time in Patent Office: 1,057 Days
• Field of Search: 128/633, 128/664, 356/39, 356/40, 356/41
• 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 5/1455 using optical sensors, e.g. spectral photometrical oximeters
• CPC Class Codes: G01N 21/314 with comparison of measurements at specific and non-specific wavelengths dual wavelength spectrometry G01J3/427
• CPC Class Codes: G01N 21/49 within a body or fluid

Abstract

Biochemical components and changes in the components are measured by directing light of several wavelengths into a body at one location, sensing light at the wavelengths emerging from the body at a plurality of distances from the one location, and ascertaining biochemical component characteristics in the body as a function of variations, with respect to distance, of the logarithm of the ratio of the light sensed to the light directed into the body. The variations with respect to distance are in the form of the derivative and square of the derivatives of the logarithm.

Claims

1. The method, comprising:

directing electromagnetic radiation at one or more wavelengths into a body at one location;

sensing electromagnetic radiation at the wavelengths emerging from the body at a plurality of distances from the one location; and

ascertaining biochemical component characteristics in the body as a function of differences in a negative logarithm of the electromagnetic radiation sensed for the wavelengths at the plurality of distances, and a scattering coefficient relative to the wavelengths at each of the distances.

2. The method as in claim 1, wherein the differences with respect to distance are in a form of the derivative of the negative logarithm.

3. The method as in claim 2, wherein the step of ascertaining further includes determining concentrations of biochemical components as a function of the square of said derivative, and a molar extinction coefficient.

4. The method as in claim 3, wherein the sensing is performed on a number of elements j by a plurality of detectors each at one of the plurality of distances, and wherein the step of determining includes calculating a concentration C_j each of the elements j on the basis of equation ##EQU22## and OD=-log(I_o /I_i), μ

_a is an extinction coefficient, μ

'"'"'_s is a scattering coefficient, and ε

_j is a known molar extinction coefficient for each of the elements j.

5. The method as in claim 3, wherein the sensing is performed on a number of elements j by a plurality of detectors each at one of the plurality of distances, and wherein the step of determining includes calculating a concentration C_j for each of the elements j on the basis of equation ##EQU23## and OD=-log(I_o /I_i), μ

_a =an extinction coefficient, μ

_a is an extinction coefficient, μ

'"'"'_s is a scattering coefficient, and ε

_j is a known molar extinction coefficient for each of the elements j.

6. The method as in claim 5, wherein the step of calculating includes using the matrix formula ##EQU24## where μ

_ai is for the wavelength λ

i and N is at least equal to a number of compounds determined plus 1 for a baseline.

7. The method as in claim 3, wherein the step of determining includes calculating concentrations from the matrix ##EQU25##

8. The method as in claim 3, wherein the step of determining includes calculating concentrations from the matrix ##EQU26## and calculating changes in concentration from the matrix ##EQU27##

9. The method as in claim 2, wherein the step of ascertaining further includes determining changes, with respect to time, of concentrations of biochemical components as a function of changes in time of the square of said derivative, and a molar extinction coefficient.

10. The method as in claim 9, wherein the step of determining includes calculating changes in concentrations from the matrix ##EQU28##

11. The method as in claim 1, wherein the step of ascertaining further includes determining concentrations of biochemical components as a function of the square of said differences.

12. The method as in claim 1, wherein the step of ascertaining further includes determining concentrations of biochemical components as a function of the square of said differences and a molar extinction coefficient.

13. The method as in claim 1, wherein the step of ascertaining further includes determining changes, with respect to time, of concentrations of biochemical components as a function of changes in time of the square of said differences and a molar extinction coefficient.

14. The method as in claim 1, wherein the step of directing directs the radiation at each wavelength in an impulse or sine wave form.

15. An apparatus, comprising:

means for directing electromagnetic radiation at one or more wavelengths into a body at one location;

means for sensing electromagnetic radiation at the plurality of wavelengths emerging from the body at a plurality of distances from the one location; and

means for ascertaining biochemical component characteristics in the body as a function of differences in a negative logarithm of the electromagnetic radiation sensed for the wavelengths at the plurality of distances, and a scattering coefficient relative to the wavelengths at each of the distances.

16. The apparatus as in claim 15, wherein, in the means for ascertaining, the differences with respect to distance are in the form of a derivative of the negative logarithm for the wavelengths.

17. The apparatus as in claim 16, wherein the means for ascertaining includes means for determining concentrations of biochemical components as a function of the square of said derivative, and a molar extinction coefficient.

18. The apparatus as in claim 17, wherein the means for sensing includes a plurality of detectors each for one of elements j and each at one of the distances, and wherein the means for determining includes means for calculating a concentration c_j for each of the elements j on the basis of equation ##EQU29## where OD=-log(I_o /I_i), μ

_a is an extinction coefficient, μ

'"'"'_s is a scattering coefficient, and ε

_j is a known molar extinction coefficient of the element j.

19. The apparatus as in claim 17, wherein the means for sensing includes a plurality of detectors each for one of elements j and each at one of the distances, and wherein the means for determining includes means for calculating a concentration C_j for each of the elements j on the basis of equation ##EQU30## and OD=-log(I_o /I_i), ε

_j is a known molar extinction coefficient for each of the elements j, μ

_a is an extinction coefficient, and μ

'"'"'_s is a scattering coefficient.

20. The apparatus as in claim 19, wherein the means for calculating includes means for executing the matrix formula ##EQU31## where μ

_ai is for the wavelength λ

i and N is at least equal to the number of compounds determined plus 1 for a baseline.

21. The apparatus as in claim 17, wherein the means for determining includes means for calculating concentrations from the matrix ##EQU32##

22. The apparatus as in claim 17, wherein the means for determining includes means for calculating concentrations from the matrix ##EQU33## and means for calculating changes in concentration from the matrix ##EQU34##

23. The apparatus as in claim 16, wherein the means for ascertaining further includes means for determining changes in concentrations of biochemical components as a function of changes in the square of said derivative, and a molar extinction coefficient.

24. The apparatus as in claim 23, wherein the means for determining includes means for calculating changes in concentrations from the matrix ##EQU35##

25. The apparatus as in claim 15, wherein the means for ascertaining further includes means for determining concentrations of biochemical components as a function of the square of said differences.

26. The apparatus as in claim 15, wherein the means for ascertaining further includes means for determining concentrations of biochemical components as a function of the square of said differences and a molar extinction coefficient.

27. The apparatus as in claim 15, wherein the means for ascertaining further includes means for determining differences in concentrations of biochemical components as a function of the square of said differences and a molar extinction coefficient.

28. An apparatus as in claim 15, wherein said directing means directs radiation at each of the wavelengths in a pulse or sine wave form.