Methods and systems for optically characterizing a turbid material using a structured incident beam

• US 8,634,077 B2
• Filed: 10/01/2009
• Issued: 01/21/2014
• Est. Priority Date: 10/01/2008
• Status: Expired due to Fees

• Current Assignee: East Carolina University
• Original Assignee: East Carolina University
• Inventors: Hu, Xin-Hua, Chen, Cheng
• Primary Examiner(s): Chowdhury, Tarifur
• Assistant Examiner(s): AKANBI, ISIAKA O
• Application Number:
  US13/122,062
• Publication Number:
  US 20110286000A1
• Time in Patent Office: 1,573 Days
• Field of Search: 356445-446
• US Class Current: 356/445
• CPC Class Codes: G01N 2021/4709 Backscatter
• CPC Class Codes: G01N 2021/4735 Solid samples, e.g. paper, glass
• CPC Class Codes: G01N 21/4738 Diffuse reflection precedence is given to G01N21/55 - G01N21/57 if specular component is taken into consideration, e.g. also for testing fluids, fibrous materials
• CPC Class Codes: G01N 21/4785 Standardising light scatter apparatus; Standards therefor
• CPC Class Codes: G01N 2201/0635 Structured illumination, e.g. with grating

Abstract

Methods and systems for optically characterizing a turbid sample are provided. A structured light beam is impinged on the sample. The sample includes an embedded region. A reflected light image of the structured light beam is detected from the sample. A measured reflectance image of the structured light beam for the sample is determined based on the reflected light image and a reflectance standard. The following parameters are determined: absorption coefficients ÿa, scattering coefficient ÿs and anisotropy factor g of the sample from the reflectance image. A size parameter of the embedded region is estimated based on the absorption coefficients ÿa, scattering coefficient ÿs and/or anisotropy factor g of the sample from the measured reflectance image.

Claims

1. A method for optically characterizing a turbid sample, the method comprising:

impinging a structured light beam on the sample, wherein the sample comprises an embedded region;

detecting a reflected light image of the structured light beam from the sample;

determining a measured reflectance image of the structured light beam for the sample based on the reflected light image and a reflectance standard;

determining an absorption coefficient μ

_a, a scattering coefficient μ

_s·

and/or an anisotropy factor g of the sample from the reflectance image;

estimating a size parameter of the embedded region based on the absorption coefficients μ

_a, scattering coefficient μ

_s and/or anisotropy factor g of the sample from the measured reflectance image;

wherein determining a measured reflectance image comprises the reflected light image of the sample normalized by a reflected light image of the reflectance standard; and

wherein the reflectance standard is a calibrated diffuse reflectance standard.

2. The method of claim 1, wherein the light beam is an incoherent, full-field light beam.

3. The method of claim 1, wherein the embedded region comprises a tissue abnormality, and the size parameter of the embedded region is correlated to a likelihood of cancer malignancy.

4. The method of claim 3, wherein the tissue abnormality comprises an epithelial abnormality, and the size parameter is a depth of the epithelial abnormality.

5. The method of claim 1, wherein the structured light beam is formed by passing an incoherent light beam through a stencil having transmissive and non-transmissive or partially transmissive regions to thereby form a structured profile.

6. The method of claim 5, wherein the structured profile is a grating pattern.

7. The method of claim 1, wherein the measured reflectance image is detected by a detector that is spaced-apart from the sample.

8. The method of claim 1, wherein the absorption coefficient μ

_a, scattering coefficient μ

_s and/or anisotropy factor g of the sample from the refectance image is based on Monte Carlo simulation on the basis of radiative transfer theory.

9. The method of claim 8, wherein determining the absorption coefficient μ

_a, scattering coefficient μ

_s and/or anisotropy factor g of the sample from the reflectance image is further based on an optical diffusion model.

10. A system for optically characterizing a turbid sample, the system comprising:

a structured light beam source configured to impinge a beam on a sample, wherein the sample comprises an embedded region;

a detector configured to detect a reflected light image of the structured light beam from the sample;

a signal analyzer configured to determine a measured reflectance image of the structured light beam for the sample based on the reflected light image of the sample normalized by another reflected light image of the reflectance standard, and to determine an absorption coefficient μ

_a, scattering coefficient μ

_s, and anisotropy factor g of the sample from the measured reflectance image, to estimate a size parameter of the embedded region based on the absorption coefficients μ

_a, scattering coefficient μ

_s, and/or anisotropy factor g of the sample from the measured reflectance image;

wherein the signal analyzer is further configured to determine a measured reflectance image by normalizing the reflected light image of the sample by the reflected light image of the reflectance standard; and

wherein the reflectance standard is a calibrated diffuse reflectance standard.

11. The system of claim 10, wherein the light beam source is configured to provide an incoherent, full-field light beam.

12. The system of claim 10, wherein the embedded region comprises a tissue abnormality, and the signal analyzer is configured to correlate the size parameter of the embedded region to a likelihood of cancer malignancy.

13. The system of claim 12, wherein the tissue abnormality comprises an epithelial abnormality, and the size parameter is a depth of the epithelial abnormality.

14. The system of claim 10, wherein the incoherent light beam source further comprises a stencil having transmissive and non-transmissive or partially transmissive regions to thereby form a structured profile.

15. The system of claim 14, wherein the structured profile is a grating pattern.

16. The system of claim 10, wherein the detector is spaced-apart from the sample.

17. The system of claim 10, wherein the signal analyzer is configured to determine the absorption coefficient μ

_a, scattering coefficient μ

_s and/or anisotropy factor g of the sample from the reflectance image based on a Monte Carlo simulation on the basis of radiative transfer theory.

18. The system of claim 17, wherein the signal analyzer is configured to determine the following:

absorption coefficients μ

_a, reduced scattering coefficient μ

_s′

of the sample from the reflectance image based on an optical diffusion model.

19. A method for optically characterizing a turbid, biological tissue sample, the method comprising:

impinging a structured light beam on the tissue sample, wherein the tissue sample comprises an embedded region;

detecting a reflected light image of the structured light beam from the tissue sample;

determining a measured reflectance image of the structured light beam for the tissue sample based on the reflected light image of the sample normalized by a reflected light image of the reflectance standard, wherein the reflectance standard is a calibrated diffuse reflectance standard;

determining an absorption coefficient μ

_a, a scattering coefficient μ

_s, and/or an anisotropy factor g of the tissue sample from the reflectance image;

estimating a size parameter of the embedded region based on the absorption coefficients μ

_a, scattering coefficient μ

_s, and/or anisotropy factor g of the tissue sample from the measured reflectance image; and

assessing a health parameter of the tissue sample based on the size parameter of the embedded region.