Method of measuring tissue optical properties using an optical beam of oblique incidence and uses thereof

• US 5,630,423 A
• Filed: 01/31/1996
• Issued: 05/20/1997
• Est. Priority Date: 01/31/1996
• Status: Expired due to Fees

• Current Assignee: Texas A&M University System
• Original Assignee: Texas A&M University System
• Inventors: Wang, Lihong, Jacques, Steven L.
• Primary Examiner(s): Lateef, Marvin M.
• Assistant Examiner(s): MANTIS MERCADER, ELENI M
• Application Number:
  US08/594,757
• Time in Patent Office: 475 Days
• Field of Search: 128/664, 128/665, 356/338, 356/340, 356/446
• US Class Current: 600/475
• 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: G01N 21/47 Scattering, i.e. diffuse reflection G01N21/25, G01N21/41 take precedence G01N21/55 takes precedence

Abstract

The present invention provides a method of determining the reduced scattering coefficient of a turbid medium having a smaller absorption coefficient than the reduced scattering coefficient by directing an optical beam obliquely incident to the medium and determining the reduced scattering coefficient as a function of the distance between the incident point and the center of the diffused reflectance, the incident angle, the relative refractive index and the reduced scattering coefficient.

Claims

1. A method of determining the reduced scattering coefficient of a turbid medium having an absorption coefficient less than the reduced scattering coefficient of said medium, comprising the steps of:

directing an optical beam that is obliquely incident upon said medium;

determining the reduced scattering coefficient of the medium using the diffuse reflectance profile based on the following formula;

##EQU7## wherein Δ

x is the distance between the incident point and the center of the diffuse reflectance that is several transport mean free paths away from the center;

α

_i is the incident angle;

n is the relative refractive index; and

μ

_s '"'"' is the reduced scattering coefficient.

2. The method of claim 1, wherein said turbid medium is a biological sample.

3. The method of claim 1, wherein the angle of said optical beam is from about 5°

to about 85°

.

4. The method of claim 1, wherein the absorption coefficient less than about 10% of the reduced scattering coefficient of said medium.

5. A method of determining an optical property of a turbid medium having an absorption coefficient similar to the reduced scattering coefficient of the medium, comprising the steps of:

directing an optical beam that is obliquely incident upon said medium;

determining the reduced scattering coefficient of the medium using the diffuse reflectance profile based on the following formula;

##EQU8## wherein Δ

x is the distance between the incident point and the center of the diffuse reflectance that is several transport mean free paths away from the center;

α

_i is the incident angle;

n is the relative refractive index;

μ

a is the absorption coefficient; and

μ

_s '"'"' is the reduced scattering coefficient.

6. The method of claim 5, wherein said turbid medium is a biological sample.

7. The method of claim 5, wherein the angle of said optical beam is from about 5°

to about 85°

.

8. The method of claim 5, wherein said optical property is selected from the group consisting of absorption coefficient.