# US 2018/0249911 A1 · Diffusing wave spectroscopy apparatus and control method therefor > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2018/0249911 A1 - Document ID: US20180249911A1 - Status: Published application - Kind: A1 - Application number: 15/449,195 - Filed: 2017-03-03 - Published: 2018-09-06 - Earliest claimed: 2017-03-03 - Assignees: Canon U.S.A., Inc. - Applicants: Canon USA Inc. - Inventors: Masaki Hosoda; Haruo Nakaji - Web page: https://patentgrep.com/patent/US20180249911A1 ## CPC - A61B 5/0075: {by spectroscopy, i.e. measuring spectra, e.g. Raman spectroscopy, infrared absorption spectroscopy (A61B5/0071 takes precedence)} - A61B 5/6826: {Finger} - G01N 21/474: {Details of optical heads therefor, e.g. using optical fibres} - G01N 21/4785: {Standardising light scatter apparatus; Standards therefor} - A61B 5/021: Measuring pressure in heart or blood vessels - A61B 5/026: Measuring blood flow {(A61B3/1233, A61B3/1241 take precedence)} - G01N 2021/4742: {comprising optical fibres} - G01N 2021/4778: {Correcting variations in front distance} - G01N 2201/121: Correction signals - A61B: DIAGNOSIS; SURGERY; IDENTIFICATION (usefulness limited to only animals A61D) - G01N: INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES (measuring or testing apparatus or processes other than immunoassay, involving enzymes or microorganisms C12M, C12Q) ## Abstract A DWS apparatus includes a coherent light source, a photodetector, a control unit which can measure an intensity autocorrelation function, a measuring unit which can measure a source-detector distance to obtain source-detector distance data, and a calibrating unit which adjusts the intensity autocorrelation function by using the source-detector distance data. The calibrating unit calibrates the intensity autocorrelation function by adjusting the time constant of the autocorrelation function based on a comparison of the source-detector distance to the time constant of the intensity autocorrelation function. ## Claims ### Claim 1 A diffusing wave spectroscopy apparatus, comprising: a source configured to emit light to irradiate tissue of a subject; a detector configured to detect at least part of the light after propagation through the tissue; a distance measurement unit configured to measure a source-detector distance; a control unit configured to obtain an intensity autocorrelation function by using light intensity data corresponding to light intensity signals obtained from the detector, and to derive a time decay value (τdecay) of the intensity autocorrelation function; and a calibrating unit configured to calibrate the intensity autocorrelation function by adjusting the time decay value of the intensity autocorrelation function based on the measured source-detector distance. ### Claim 2 (depends on 1) The diffusing wave spectroscopy apparatus according to claim 1, wherein the source includes a coherent light source and a source optical fiber, the source optical fiber having a proximal end thereof connected to the coherent light source and a distal end thereof arranged in contact with the tissue of the subject, and the detector includes a photodetector and a detector optical fiber, the detector optical fiber having a proximal end thereof connected to the photodetector and a distal end thereof arranged in contact with the subject at a location other than the distal end of the source optical fiber. ### Claim 3 (depends on 2) The diffusing wave spectroscopy apparatus according to claim 2, wherein the distance measurement unit measures a distance between the distal end of the source optical fiber and the distal end of the detector optical fiber both in contact with the subject, as the source-detector distance. ### Claim 4 (depends on 1) The diffusing wave spectroscopy apparatus according to claim 1, wherein the distance measurement unit includes at least one linear encoder. ### Claim 5 (depends on 1) The diffusing wave spectroscopy apparatus according to claim 1, wherein the distance measurement unit includes at least one rotary encoder. ### Claim 6 (depends on 1) The diffusing wave spectroscopy apparatus according to claim 1, wherein the probe includes a clamp configured to receive therein an anatomical extremity of a subject. ### Claim 7 (depends on 1) The diffusing wave spectroscopy apparatus according to claim 1, wherein the calibrating unit is configured to calibrate the intensity autocorrelation function by adjusting the time decay value (τdecay) of the intensity autocorrelation function according to the following equation y=0.0059ê(−0.162x), where y is a value of a time decay function and x is the measured source-detector distance. ### Claim 8 (depends on 1) The diffusing wave spectroscopy apparatus according to claim 1, wherein the calculation unit derives a time decay value (τdecay) of the intensity autocorrelation function based on tissue or blood condition of the subject, wherein the calculation unit is further configured to calculate a time constant value (τ) of intensity autocorrelation function based on the measured source-detector distance, and wherein the calibration unit is configured to calibrate the intensity autocorrelation function by comparing the time decay value (τdecay) of the intensity autocorrelation function to the time constant value (τ) calculated using the measured source-detector distance, and determining whether a difference thereof is below a threshold value. ### Claim 9 (depends on 7) The diffusing wave spectroscopy apparatus according to claim 7, wherein the calibration unit calibrates the intensity autocorrelation function when the difference is below the threshold value. ### Claim 10 (depends on 7) The diffusing wave spectroscopy apparatus according to claim 7, wherein the calibration unit is configured to output a warning signal when the difference is equal to or above the threshold value. ### Claim 11 A method of calibrating measurements of a diffusing wave spectroscopy apparatus, comprising: emitting a coherent light from a source to irradiate tissue of a subject; detecting, using a detector, light intensity of scattered light after propagation of the light through the tissue of the subject; measuring a source-detector distance; calculating an intensity autocorrelation function by using light intensity data corresponding to light intensity signals obtained from the detector, and deriving a time decay value of the intensity autocorrelation function; and calibrating the intensity autocorrelation function by adjusting the time decay value of the intensity autocorrelation function based on the measured source-detector distance. ### Claim 12 (depends on 11) The method according to claim 11, wherein measuring the source-detector distance includes measuring a distance between a distal end of a source optical fiber and a distal end of a detector optical fiber both in contact with the subject and separate from each other. ### Claim 13 (depends on 12) The method according to claim 12, wherein measuring the source-detector distance includes measuring a distance between the distal end of the source optical fiber and the distal end of the detector optical fiber using at least one linear encoder. ### Claim 14 (depends on 12) The method according to claim 12, wherein measuring the source-detector distance includes measuring a distance between the distal end of the source optical fiber and the distal end of the detector optical fiber using at least one rotary encoder. ### Claim 15 (depends on 11) The method according to claim 11, wherein calibrating the intensity autocorrelation function includes adjusting the time decay value (τdecay) of the intensity autocorrelation function according to the following equation y=0.0059ê(−0.162x), where y is a value of a time decay function and x is the measured source-detector distance. ### Claim 16 (depends on 11) The method according to claim 11, further comprising: calculating a time constant value (τ) of the intensity autocorrelation function based on the measured source-detector distance, wherein the deriving a time decay value (τdecay) of the intensity autocorrelation function is based on tissue or blood condition of the subject, and wherein calibrating the intensity autocorrelation function includes comparing the time decay value (τdecay) of the intensity autocorrelation function to the time constant value (τ) calculated using the measured source-detector distance, and determining whether a difference thereof is below a threshold value. ### Claim 17 (depends on 16) The method according to claim 16, wherein, when the difference is below the threshold value, calibrating the intensity autocorrelation function includes adjusting the time decay value (τdecay) of the intensity autocorrelation function according to the following equation yt2—calibrated=yt1−{f(xt1)−f(xt2)} where x is the measured source-detector distance, y is a value of a time decay function, t1 is a time after t1 seconds have passed from a start time t0, and t2 is a time after a minimum time increment has passed from t1. ### Claim 18 (depends on 16) The method according to claim 16, wherein, when the difference is equal to or above the threshold value, calibrating the intensity autocorrelation function includes outputting a warning signal and rearranging the source and detector on the subject. ### Claim 19 A system comprising: one or more processors; and one or more computer-readable media coupled to the one or more processors, the one or more computer-readable media storing instructions that, when executed by the one or more processors, cause the one or more processors to perform operations comprising: emitting a coherent light from a source to irradiate tissue of a subject; detecting, using a detector, light intensity of scattered light after propagation of the light through the tissue of the subject; measuring a source-detector distance; calculating an intensity autocorrelation function by using light intensity data corresponding to light intensity signals obtained from the detector, and deriving a time decay value of the intensity autocorrelation function; and calibrating the intensity autocorrelation function by adjusting the time decay value of the intensity autocorrelation function based on the measured source-detector distance. ### Claim 20 A computer-readable medium storing instructions that, when executed by one or more processors, cause the one or more processors to perform operations comprising: emitting a coherent light from a source to irradiate tissue of a subject; detecting, using a detector, light intensity of scattered light after propagation of the light through the tissue of the subject; measuring a source-detector distance; calculating an intensity autocorrelation function by using light intensity data corresponding to light intensity signals obtained from the detector, and deriving a time decay value of the intensity autocorrelation function; and calibrating the intensity autocorrelation function by adjusting the time decay value of the intensity autocorrelation function based on the measured source-detector distance.