Method and apparatus for measuring internal property distribution

• US 6,075,610 A
• Filed: 05/09/1997
• Issued: 06/13/2000
• Est. Priority Date: 05/10/1996
• Status: Expired due to Term

• Current Assignee: Hamamatsu Photonics KK
• Original Assignee: Hamamatsu Photonics KK
• Inventors: Ohta, Kazuyoshi, Ueda, Yukio, Tsuchiya, Yutaka
• Primary Examiner(s): Kim, Robert H.
• Assistant Examiner(s): Smith, Zandra V.
• Application Number:
  US08/853,879
• Time in Patent Office: 1,131 Days
• Field of Search: 600/310, 600/316, 600/322, 600/323, 600/328, 600/339, 600/473, 600/476, 356/337, 356/342, 356/343, 356/432
• US Class Current: 356/432
• CPC Class Codes: G01N 21/49 within a body or fluid

Abstract

A method for measuring an internal property distribution which includes making measurement light incident from a plurality of light incidence positions on a surface of a measured object, detecting the measurement light that has passed through the object, successively or simultaneously, at at least one light detection position out of a plurality of light detection positions on the surface of the object. A plurality of measurement values obtained by a plurality of combinations of the light incidence position and said light detection position are extracted. A mean value of the measured values are calculated to obtain a reference value and a change amount of a predetermined internal property in each of the plurality of regions of the object are calculated using the plurality of measured values obtained. The reference value thereby establishing an internal property change amount distribution in the object.

Claims

1. A method for measuring an internal property distribution, comprising:

making measurement light incident successively into a measurement object from a plurality of light incidence positions onto a surface of said measurement object;

detecting the measurement light, said measurement light having passed through the measurement object successively or simultaneously, at at least one light detection position out of a plurality of light detection positions on the surface of said measurement object and in a predetermined positional relation with respect to a light incidence position at which the measurement light to be measured was incident;

obtaining a measured value of a predetermined parameter of said measurement light based on incident measurement light detected at each light detection position;

extracting a plurality of said measured values obtained by a plurality of combinations of said light incidence position and said light detection position, said positional relation of which is relatively identical, and calculating a mean value of the measured values to obtain a reference value in the positional relation; and

calculating a change amount of a predetermined internal property in each region of said measurement object divided into a plurality of regions using said plurality of measured values obtained by said plurality of combinations, and said reference value, thereby obtaining an internal property change amount distribution in the measurement object.

2. A method for measuring an internal property distribution, comprising:

making measurement light incident successively into a measurement object from a plurality of light incidence positions onto a surface of a said measurement object;

detecting the measurement light, said measurement light having passed through the measurement object successively or simultaneously, at at least one light detection position out of a plurality of light detection positions on the surface of said measurement object and in a predetermined positional relation with respect to a light incidence position at which the measurement light to be measured was incident;

obtaining a measured value of a predetermined parameter of said measurement light based on each incident measurement light detected at each light detection position;

extracting a plurality of said measured values obtained by a plurality of combinations of said light incidence position and said light detection position, said positional relation of which is relatively identical, and calculating a mean value of the measured values to obtain a reference value in the positional relation; and

calculating a change amount of a predetermined internal property in each region of said measurement object divided into a plurality of regions using said plurality of measured values obtained by said plurality of combinations, and said reference value, thereby obtaining an internal property change amount distribution of the measurement object,

wherein said internal property is an absorption coefficient,

said method further comprising;

obtaining a mean absorption coefficient and a mean reduced scattering coefficient of said object; and

selecting a spread function corresponding to said mean absorption coefficient and mean reduced scattering coefficient,

wherein in said obtaining the internal property change amount distribution, a change amount of the absorption coefficient in said each region is calculated using said plurality of measured values, said reference value, and said spread function.

3. The method according to claim 2, wherein, in said step of obtaining said mean absorption coefficient and mean reduced scattering coefficient, said mean absorption coefficient and mean reduced scattering coefficient are obtained based on said reference value.

4. The method according to claim 2, further comprising calculating an absolute value of the absorption coefficient in said each region, using said change amount of the absorption coefficient and said mean absorption coefficient, and thereby obtaining an absorption coefficient absolute value distribution in said object.

5. The method according to claim 4, further comprising calculating a concentration of an absorptive constituent in said each region, using said absolute value of the absorption coefficient, and thereby obtaining an absorptive constituent concentration distribution in said object.

6. The method according to claim 5, wherein said object contains at least two absorptive constituents,

wherein the measurement light incident into said object in said light incidence step has at least two wavelengths at which absorption coefficients for the absorptive constituents are different from each other;

wherein, in said light detection, said measurement light having the at least two wavelengths is detected, respectively;

wherein, in said obtaining the measured values, said measured values are obtained for each of said measurement light having the at least two wavelengths;

wherein, in said obtaining the reference value, said mean value is calculated for each of said measurement light having the at least two wavelengths;

wherein, in said obtaining the internal property change amount distribution, the change amount of said absorption coefficient is calculated for each of said measurement light having the at least two wavelengths;

wherein, in said obtaining the absorption coefficient absolute value distribution, said absolute value of the absorption coefficient is calculated for each of said measurement light having the at least two wavelengths; and

wherein, in said obtaining the absorptive constituent concentration distribution, said concentration of the absorptive constituent is calculated for each of said measurement light having the at least two wavelengths, thereby obtaining a concentration distribution of said each absorptive constituent in said object.

7. A method for measuring an internal property distribution, comprising:

making measurement light incident successively into a measurement object from a plurality of light incidence positions onto a surface of a said measurement object;

detecting the measurement light, said measurement light having passed through the measurement object successively or simultaneously, at at least one light detection position out of a plurality of light detection positions on the surface of said measurement object and in a predetermined positional relation with respect to a light incidence position at which the measurement light to be measured was incident;

obtaining a measured value of a predetermined parameter of said measurement light based on each incident measurement light detected at each light detection position;

extracting a plurality of said measured values obtained by a plurality of combinations of said light incidence position and said light detection position, said positional relation of which is relatively identical, and calculating a mean value of the measured values to obtain a reference value in the positional relation; and

calculating a change amount of a predetermined internal property in each region of said measurement object divided into a plurality of regions using said plurality of measured values obtained by said plurality of combinations, and said reference value, thereby obtaining an internal property change amount distribution of the measurement object,

wherein said internal property is a reduced scattering coefficient,

said method further comprising;

obtaining a mean absorption coefficient and a mean reduced scattering coefficient of said measurement object; and

selecting a spread function corresponding to said mean absorption coefficient and mean reduced scattering coefficient,

wherein in said obtaining the internal property change amount distribution, a change amount of the reduced scattering coefficient in said each region is calculated using said plurality of measured values, said reference value, and said spread function.

8. The method according to claim 7, wherein, in said obtaining said means absorption coefficient and mean reduced scattering coefficient, said mean absorption coefficient and mean reduced scattering coefficient are obtained based on said reference value.

9. The method according to claim 7, further comprising calculating an absolute value of the reduced scattering coefficient in said each region, using the change amount of said reduced scattering coefficient and said mean reduced scattering coefficient, and thereby obtaining a reduced scattering coefficient absolute value distribution in said object.

10. A method for measuring an internal property distribution, comprising:

making measurement light incident successively into a measurement object from a plurality of light incidence positions onto a surface of a said measurement object;

detecting the measurement light, said measurement light having passed through the measurement object successively or simultaneously, at at least one light detection position out of a plurality of light detection positions on the surface of said measurement object and in a predetermined positional relation with respect to a light incidence position at which the measurement light to be measured was incident;

obtaining a measured value of a predetermined parameter of said measurement light based on each incident measurement light detected at each light detection position;

extracting a plurality of said measured values obtained by a plurality of combinations of said light incidence position and said light detection position, said positional relation of which is relatively identical, and calculating a mean value of the measured values to obtain a reference value in the positional relation; and

calculating a change amount of a predetermined internal property in each region of said measurement object divided into a plurality of regions using said plurality of measured values obtained by said plurality of combinations, and said reference value, thereby obtaining an internal property change amount distribution of the measurement object,

wherein said internal property is a refractive index,

said method further comprising;

obtaining a mean absorption coefficient, a mean reduced scattering coefficient, and a mean refractive index of said measurement object; and

selecting a spread function corresponding to said mean absorption coefficient, mean reduced scattering coefficient, and mean refractive index;

wherein in said obtaining the internal property change amount distribution, a change amount of the refractive index in said each region is calculated using said plurality of measured values, said reference value, and said spread function.

11. The method according to claim 10, wherein, in said obtaining said mean absorption coefficient, mean reduced scattering coefficient, and mean refractive index, at least the mean absorption coefficient and mean reduced scattering coefficient are obtained based on said reference value.

12. The method according to claim 10, further comprising calculating an absolute value of the refractive index in said each region, using said change amount of the refractive index and said mean refractive index, and thereby obtaining a refractive index absolute value distribution in said object.

13. A method for measuring an internal property distribution, comprising:

making measurement light incident successively into a measurement object from a plurality of light incidence positions onto a surface of a said measurement object;

detecting the measurement light, said measurement light having passed through the measurement object successively or simultaneously, at at least one light detection position out of a plurality of light detection positions on the surface of said measurement object and in a predetermined positional relation with respect to a light incidence position at which the measurement light to be measured was incident;

obtaining a measured value of a predetermined parameter of said measurement light based on each incident measurement light detected at each light detection position;

extracting a plurality of said measured values obtained by a plurality of combinations of said light incidence position and said light detection position, said positional relation of which is relatively identical, and calculating a mean value of the measured values to obtain a reference value in the positional relation; and

calculating a change amount of a predetermined internal property in each region of said measurement object divided into a plurality of regions using said plurality of measured values obtained by said plurality of combinations, and said reference value, thereby obtaining an internal property change amount distribution of the measurement object,

further comprising displaying an image indicating the distribution inside said measurement object, based on said distribution obtained.

14. An apparatus for measuring an internal property distribution, comprising:

light incidence means for making measurement light incident successively into a measurement object from a plurality of light incidence positions onto a surface of said measurement object;

light detection means for detecting the measurement light, said measurement light having passed though the measurement object successively or simultaneously, at at least one light detection position out of a plurality of light detection positions on the surface of the measurement object and in a predetermined positional relation with respect to a light incidence position at which the measurement light to be measured was incident;

measured value acquiring means for obtaining a measured value of a predetermined parameter of the measurement light based on each measurement light detected at each light detection position;

reference value calculating means for extracting a plurality of said measured values obtained by a plurality of combinations of said light incidence position and said light detection position said positional relation of which is relatively identical and calculating a mean value of the measured values to obtain a reference value in the positional relation; and

internal property change amount calculating means for calculating a change amount of a predetermined internal property in each region of said object divided into a plurality of regions using said plurality of measured values obtained by said plurality of combinations, and said reference value, and thereby obtaining an internal property change amount distribution in the measurement object.

15. An apparatus for measuring an internal property distribution, comprising:

light incidence means for making measurement light incident successively into a measurement object from a plurality of light incidence positions onto a surface of said measurement object;

light detection means for detecting the measurement light, said measurement light having passed through the measurement object successively or simultaneously, at at least one light detection position out of a plurality of light detection positions on the surface of the measurement object and in a predetermined positional relation with respect to a light incidence position at which the measurement light to be measured was incident;

measured value acquiring means for obtaining a measured value of a predetermined parameter of the measurement light based on each measurement light detected at each light detection position;

reference value calculating means for extracting a plurality of said measured values obtained by a plurality of combinations of said light incidence position and said light detection position said positional relation of which is relatively identical and calculating a mean value of the measured values to obtain a reference value in the positional relation; and

internal property change amount calculating means for calculating a change amount of a predetermined internal property in each region of said object divided into a plurality of regions using said plurality of measured values obtained by said plurality of combinations, and said reference value, and thereby obtaining an internal property change amount distribution in the object,

wherein said internal property is an absorption coefficient,

said apparatus further comprising;

mean absorption and scattering coefficient detecting means for obtaining a mean absorption coefficient and a mean reduced scattering coefficient of said object, and

spread function selecting means for selecting a spread function corresponding to said mean absorption coefficient and mean reduced scattering coefficient;

wherein, in said internal property change amount calculating means, a change amount of the absorption coefficient in said each region is calculated using said plurality of measured values, said reference value, and said spread function.

16. The apparatus according to claim 15, wherein in said mean absorption and scattering coefficient detecting means, said mean absorption coefficient and mean reduced scattering coefficient are obtained based on said reference value.

17. The apparatus according to claim 15, further comprising absorption coefficient absolute value calculating means for calculating an absolute value of the absorption coefficient in said each region, using said change amount of the absorption coefficient and said mean absorption coefficient, and thereby obtaining an absorption coefficient absolute value distribution in said object.

18. The apparatus according to claim 17, further comprising absorptive constituent concentration calculating means for calculating a concentration of an absorptive constituent in said each region, using said absolute value of the absorption coefficient, and thereby obtaining an absorptive constituent concentration distribution in said object.

19. The apparatus according to claim 18, wherein said measurement object contains at least two absorptive constituents;

wherein the measurement light incident into said object in said light incidence means has at least two wavelengths at which absorption coefficients for said absorptive constituents are different from each other;

wherein in said light detection means said measurement light having the at least two wavelengths is detected respectively;

wherein in said measured value acquiring means said measured values are obtained for each of said measurement light having the at least two wavelengths;

wherein in said reference value calculating means said mean value is calculated for each of said measurement light having the at least two wavelengths;

wherein in said internal property change amount calculating means said change amount of the absorption coefficient is calculated for each of said measurement light having the at least two wavelengths;

wherein in said absorption coefficient absolute value calculating means said absolute value of the absorption coefficient is calculated for each of said measurement light having the at least two wavelengths; and

wherein in said absorptive constituent concentration calculating means said concentration of the absorptive constituent is calculated for each of said measurement light having the at least two wavelengths, thereby obtaining a concentration distribution of said each absorptive constituent in said object.

20. An apparatus for measuring an internal property distribution, comprising:

light incidence means for making measurement light incident successively into a measurement object from a plurality of light incidence positions onto a surface of said measurement object;

light detection means for detecting the measurement light, said measurement light having passed through the measurement object successively or simultaneously, at at least one light detection position out of a plurality of light detection positions on the surface of the measurement object and in a predetermined positional relation with respect to a light incidence position at which the measurement light to be measured was incident;

measured value acquiring means for obtaining a measured value of a predetermined parameter of the measurement light based on each measurement light detected at each light detection position;

reference value calculating means for extracting a plurality of said measured values obtained by a plurality of combinations of said light incidence position and said light detection position said positional relation of which is relatively identical and calculating a mean value of the measured values to obtain a reference value in the positional relation; and

internal property change amount calculating means for calculating a change amount of a predetermined internal property in each region of said object divided into a plurality of regions using said plurality of measured values obtained by said plurality of combinations, and said reference value, and thereby obtaining an internal property chance amount distribution in the object,

wherein said internal property is a reduced scattering coefficient;

said apparatus further comprising;

mean absorption and scattering coefficient detecting means for obtaining a mean absorption coefficient and a mean reduced scattering coefficient of said object; and

spread function selecting means for selecting a spread function corresponding to said mean absorption coefficient and mean reduced scattering coefficient;

wherein, in said internal property change amount calculating means, a change amount of the reduced scattering coefficient in said each region is calculated using said plurality of measured values, said reference value, and said spread function.

21. The apparatus according to claim 20, wherein in said mean absorption and scattering coefficient detecting means, said mean absorption coefficient and mean reduced scattering coefficient are obtained based on said reference value.

22. The apparatus according to claim 20, further comprising reduced scattering coefficient absolute value calculating means for calculating an absolute value of the reduced scattering coefficient in said each region, using said change amount of the reduced scattering coefficient and said mean reduced scattering coefficient, and thereby obtaining a reduced scattering coefficient absolute value distribution in said object.

23. An apparatus for measuring an internal property distribution, comprising:

light incidence means for making measurement light incident successively into a measurement object from a plurality of light incidence positions onto a surface of said measurement object;

light detection means for detecting the measurement light, said measurement light having passed through the measurement object successively or simultaneously, at at least one light detection position out of a plurality of light detection positions on the surface of the measurement object and in a predetermined positional relation with respect to a light incidence position at which the measurement light to be measured was incident;

measured value acquiring means for obtaining a measured value of a predetermined parameter of the measurement light based on each measurement light detected at each light detection position;

reference value calculating means for extracting a plurality of said measured values obtained by a plurality of combinations of said light incidence position and said light detection position said positional relation of which is relatively identical and calculating a mean value of the measured values to obtain a reference value in the positional relation; and

internal property change amount calculating means for calculating a change amount of a predetermined internal property in each region of said object divided into a plurality of regions using said plurality of measured values obtained by said plurality of combinations, and said reference value, and thereby obtaining an internal property change amount distribution in the object,

wherein said internal property is a refractive index;

said apparatus further comprising;

mean absorption and scattering coefficient detecting means for obtaining a mean absorption coefficient, a mean reduced scattering coefficient, and a mean refractive index of said object; and

spread function selecting means for selecting a spread function corresponding to said mean absorption coefficient, mean reduced scattering coefficient and mean refractive index;

wherein, in said internal property change amount calculating means, a change amount of the refractive index in said each region is calculated using said plurality of measured values, said reference value, and said spread function.

24. The apparatus according to claim 23, wherein in said mean absorption and scattering coefficient detecting means, at least said mean absorption coefficient and mean reduced scattering coefficient are obtained based on said reference value.

25. The apparatus according to claim 23, further comprising refractive index absolute value calculating means for calculating an absolute value of the refractive index in said each region, using said change amount of the refractive index and said mean refractive index, and thereby obtaining a refractive index absolute value distribution in said object.

26. An apparatus for measuring an internal property distribution, comprising:

light incidence means for making measurement light incident successively into a measurement object from a plurality of light incidence positions onto a surface of said measurement object;

light detection means for detecting the measurement light, said measurement light having passed through the measurement object successively or simultaneously, at at least one light detection position out of a plurality of light detection positions on the surface of the measurement object and in a predetermined positional relation with respect to a light incidence position at which the measurement light to be measured was incident;

measured value acquiring means for obtaining a measured value of a predetermined parameter of the measurement light based on each measurement light detected at each light detection position;

reference value calculating means for extracting a plurality of said measured values obtained by a plurality of combinations of said light incidence position and said light detection position said positional relation of which is relatively identical and calculating a mean value of the measured values to obtain a reference value in the positional relation; and

internal property change amount calculating means for calculating a change amount of a predetermined internal property in each region of said object divided into a plurality of regions using said plurality of measured values obtained by said plurality of combinations, and said reference value, and thereby obtaining an internal property change amount distribution in the object,

further comprising image display means for displaying an image indicating the distribution inside said object, based on said distribution obtained.