Methods of minimizing scattering and improving tissue sampling in non-invasive testing and imaging

• US 6,420,709 B1
• Filed: 12/27/2000
• Issued: 07/16/2002
• Est. Priority Date: 07/15/1992
• Status: Expired due to Fees

• Current Assignee: Optix LP
• Original Assignee: Optix LP
• Inventors: Block, Myron J., Sodickson, Lester
• Primary Examiner(s): Epps, Georgia
• Assistant Examiner(s): HANIG, RICHARD E
• Application Number:
  US09/749,331
• Time in Patent Office: 566 Days
• Field of Search: 250/343, 250/347, 250/341.1, 356/39, 128/633, 128/634
• US Class Current: 250/343
• CPC Class Codes: A61B 5/14532 for measuring glucose, e.g. by tissue impedance measurement
• CPC Class Codes: A61B 5/14546 for measuring analytes not otherwise provided for, e.g. ions, cytochromes
• CPC Class Codes: A61B 5/14558 by polarisation
• CPC Class Codes: G01N 2021/3137 with selection of wavelengths after the sample
• CPC Class Codes: G01N 21/359 using near infrared light
• CPC Class Codes: G01N 21/4795 spatially resolved investigating of object in scattering medium in vivo A61B
• CPC Class Codes: G01N 21/49 within a body or fluid

Abstract

An improved method and apparatus for use in optical testing of concentration in samples has been developed. The apparatus restricts the solid angle of illumination and the solid angle of detection to eliminate a high proportion of the scattered radiation while allowing the ballistic radiation and the snake-like radiation to be transmitted. In samples which contain multiple scattering centers, this allows less correction for variations in effective pathlength and allows easier calibration of the apparatus. The use of polarized radiation as a means of minimizing scattered radiation in the sample is also disclosed.

Claims

1. A device for imaging inhomogeneities in a tissue comprising:

a radiation source for illuminating a designated area of said tissue with radiation having a wavelength between 700-2500 nm, said designated area being at least comparable in size to the thickness of said tissue, said illumination of said designated area being over a restricted solid angle;

a detector comprising a plurality of detector units in an array, said detector arranged to receive radiation from only a limited solid angle with an area comparable in size to said designated area;

whereby a shadowgram of said inhomogeneities in said tissue is generated.

2. The device of claim 1 further comprising scanning means for scanning said radiation source and/or said detector across said tissue.

3. The device of claim 1 wherein said inhomogeneities comprise temperature inhomogeneities.

4. The device of claim 1 wherein said inhomogeneities comprise concentration inhomogeneities.

5. The device of claim 1 wherein said inhomogeneities comprise scattering inhomogeneities.

6. A method of imaging inhomogeneities in a tissue comprising:

illuminating a designated area of said tissue with a radiation source generating radiation having a wavelength between 700-2500 nm, said designated area being at least comparable in size to the thickness of said tissue, said illumination of said designated area being over a restricted solid angle;

detecting transmitted radiation with a detector comprising a plurality of detector units in an array, said detector arranged to receive radiation from only a limited solid angle with an area comparable in size to said designated area;

whereby a shadowgram of said inhomogeneities in said tissue is generated.

7. The method of claim 6 further comprising the step of using a scanning device to scan said radiation source and/or said detector across said tissue.

8. The method of claim 6 comprising the step of measuring temperature inhomogeneities by comparing said detected inhomogeneities with a temperature standard.

9. The method of claim 6 comprising the step of measuring concentration inhomogeneities by comparing said detected inhomogeneities with a concentration standard.

10. The method of claim 6 comprising the step of measuring scattering inhomogeneities by detecting inhomogeneities at various angles.