WO2000028302A1 - Method and device for measuring internal information of scattering absorber - Google Patents
Method and device for measuring internal information of scattering absorber Download PDFInfo
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- WO2000028302A1 WO2000028302A1 PCT/JP1999/006181 JP9906181W WO0028302A1 WO 2000028302 A1 WO2000028302 A1 WO 2000028302A1 JP 9906181 W JP9906181 W JP 9906181W WO 0028302 A1 WO0028302 A1 WO 0028302A1
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- absorption coefficient
- light
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- predetermined
- coefficient difference
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
- G01N21/47—Scattering, i.e. diffuse reflection
- G01N21/4795—Scattering, i.e. diffuse reflection spatially resolved investigating of object in scattering medium
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- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
- A61B5/00—Measuring for diagnostic purposes; Identification of persons
- A61B5/0059—Measuring for diagnostic purposes; Identification of persons using light, e.g. diagnosis by transillumination, diascopy, fluorescence
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- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
- A61B5/00—Measuring for diagnostic purposes; Identification of persons
- A61B5/145—Measuring characteristics of blood in vivo, e.g. gas concentration, pH value; Measuring characteristics of body fluids or tissues, e.g. interstitial fluid, cerebral tissue
- A61B5/1455—Measuring characteristics of blood in vivo, e.g. gas concentration, pH value; Measuring characteristics of body fluids or tissues, e.g. interstitial fluid, cerebral tissue using optical sensors, e.g. spectral photometrical oximeters
Definitions
- the present invention relates to a method and an apparatus for measuring internal information of a scattering medium, such as an absorption coefficient and a concentration of an absorbing component.
- MBL rule Based on the Micro's Beer-Lambert Law (hereinafter referred to as the “MBL rule”), a method for measuring the absorption coefficient or the concentration of an absorbing component of a scattering medium, which is a medium to be measured, is used. For example, there are methods disclosed by the present inventors in JP-A-8-94517, JP-A-10-73481, and JP-A-10-111238. Such a method based on the MBL rule has a great feature that it is basically unaffected by (1) the shape of the medium, (2) the boundary conditions, and (3) scattering. Unless otherwise specified, the same analytical formula can be applied to media having any media shape, arbitrary boundary conditions, and various scattering characteristics.
- measurement methods based on the MBL rule can be roughly divided into four types. That is, (1) time-resolved spectroscopy (hereinafter referred to as “TRS method”) using the time-resolved waveform of the detected light, (2) time-resolved spectroscopy using the time-integrated value of the time-resolved waveform and the average optical path length. Integral measurement method (Time Integrated Spectroscopy, hereinafter referred to as “TIS method”), (3) Time-resolved gate measurement method (Time Gating Spectroscopy, hereinafter referred to as “TGS method”) that uses a part of the time-resolved waveform cut out by a gate.
- TIS method Time Integrated Spectroscopy
- TGS method Time Gating Spectroscopy
- the measurement method based on the MBL rule has many advantages as described above, its measurement accuracy is not sufficient for use and application in a wide range.
- the absolute value of light intensity is affected by various individual differences due to skin color, presence or absence of hair, and the like, which causes a decrease in measurement accuracy.
- the wavelength dependence of the scattering coefficient reduces measurement accuracy.
- the calculation time for the analysis at the time of measurement was not sufficiently shortened, which made real-time measurement difficult.
- the present invention has been made in view of the above-described problems, and measures internal information of a scattering medium that can perform measurement with higher accuracy and higher speed than the conventional measurement method based on the MBL rule. It is an object to provide a method and an apparatus.
- the present inventor has found that, without using information such as the absolute value of the light intensity or the ratio thereof, a spectroscopic measurement method using the optical path length average and dispersion, or a physical quantity corresponding thereto.
- a spectroscopic measurement method using the optical path length average and dispersion or a physical quantity corresponding thereto.
- MMS method Magnetic and Variance based Spectroscopy
- the first method for measuring the internal information of the scattering medium includes the following steps: (1) light incident from two or more types of pulsed light having a predetermined wavelength into the scattering medium from a light incident position; (2) a light detection step of detecting at the light detection position the light of the two or more types of predetermined wavelengths having propagated inside the scattering medium at a light detection position, and (3) obtaining the light detection signal.
- the first apparatus for measuring internal information of a scattering medium comprises: (1) a light incidence means for causing two or more types of pulsed light having a predetermined wavelength to enter the scattering medium from a light incident position; ) Light detecting means for detecting at the light detection position the light of the two or more types of predetermined wavelengths having propagated inside the scattering medium and obtaining a light detection signal; and (3) detecting the light based on the light detection signal.
- Signal processing means for acquiring a waveform data indicating a temporal change in light intensity; and (4) an optical path for calculating, based on the waveform data, an average optical path length of a plurality of photons constituting the detection light and a dispersion.
- the above-described first method and apparatus according to the present invention are based on the TIMVS method, which is an MVS method for performing analysis in the time domain by a time-resolved integral measurement method (TIS method).
- TIS method time-resolved integral measurement method
- the average of the optical path length of detected photons (the center of gravity of the time-resolved waveform) and the dispersion can be calculated at high speed.
- SSM Simple Subtraction Method
- the second method for measuring the internal information of the scattering medium is characterized in that: (1) two or more types of modulated light having a predetermined wavelength modulated at a predetermined frequency are incident on the scattering medium from a light incident position. (2) a light detection step of detecting light of the two or more types of predetermined wavelengths propagated inside the scattering medium at a light detection position and acquiring a light detection signal; (3) a light detection step of A signal processing step of extracting the signal of the predetermined frequency component from the light detection signal; (4) a group delay of the signal of the predetermined frequency component based on the signal of the predetermined frequency component; Calculating the second-order partial differential value of the group delay and the logarithm of the amplitude, and calculating the second-order partial differential value of the logarithm of the amplitude; Absorption coefficient difference at a given wavelength of Based on a predetermined relationship established between a way to comprising the, the absorption coefficient difference calculating step of calculating the absorption coefficient difference that put in the
- the measuring device for internal information of the second scattering medium includes: (1) two or more types of modulated light modulated at a predetermined frequency and having a predetermined wavelength are incident on the scattering medium from a light incident position. (2) light detection means for detecting light of the two or more types of predetermined wavelengths having propagated inside the scattering medium at a light detection position and obtaining a light detection signal;
- the group delay of the signal of the predetermined frequency component and the second derivative of the logarithmic amplitude with respect to the modulation frequency are calculated.
- Means for calculating the partial differential value, and (5) modulation of the group delay and the logarithm of the amplitude An absorption coefficient difference calculating means for calculating the absorption coefficient difference at the predetermined wavelength based on a second-order partial differential value with respect to frequency, and a predetermined relationship established between the absorption coefficient differences at the two or more types of predetermined wavelengths;
- An apparatus comprising:
- the above-described second method and apparatus according to the present invention are based on the PMMVS method, which is the MVS method for performing analysis in the frequency domain by the phase modulation measurement method (PMS method).
- the PMMVS method has a Fourier transform relationship with the TIMVS method according to the first method and apparatus according to the present invention, and thus modulates the group delay and the logarithm of the amplitude for light of a plurality of wavelengths.
- FIG. 1 is a graph showing the relationship between the average optical path length and the absorption coefficient when the scattering coefficient is different.
- FIG. 2 is a schematic diagram showing one embodiment of a measuring device for internal information of a scattering medium according to the present invention.
- FIG. 3 is a schematic diagram showing an example of a preferred specific configuration of the device shown in FIG.
- FIG. 4 is a flow chart showing one embodiment of a method for measuring internal information of a scattering medium according to the present invention.
- FIG. 5 is a flowchart showing another embodiment of the method for measuring the internal information of the scattering medium according to the present invention.
- FIG. 6 is a schematic diagram showing another embodiment of the measuring device for internal information of the scattering medium according to the present invention.
- FIG. 7 is a schematic diagram showing an example of a preferred specific configuration of the device shown in FIG.
- FIG. 8 is a graph showing the absorption spectrum of hemoglobin.
- FIG. 9 is a graph showing the relationship between the absorption coefficient of the phantom and the average optical path length.
- the survival rate of photons propagating zigzag inside the scattering medium is an exponential function exp (— ⁇ al) of the product of the zigzag optical path length 1 (ell) and the absorption coefficient ⁇ a of the medium (scattering medium). . That is, the attenuation is represented by the product al of the zigzag optical path length 1 and the absorption coefficient ⁇ a.
- the impulse response h (t) of the scattering medium becomes a time-causal function
- C is the speed of light in the medium
- t is the flight time
- 1 is the optical path length (flying distance)
- Flight time t The speed of light C is determined by the refractive index of the scattering medium, and for example, in a living body, the value may be regarded as a constant value.
- the transport scattering coefficient (also referred to as the equivalent scattering coefficient), which will be used later, is expressed as d (1 — g) ⁇ s using ⁇ s and the average g of the cosine of the scattering angle. expressed.
- ⁇ ⁇ ( ⁇ !., ⁇ ⁇ ) -J ⁇ ° ⁇ (,, ⁇ ) ⁇ + In 5 ( ⁇ ⁇ , ⁇ ) is as ⁇ (l.2c).
- L (jus, a ) ii c ⁇ t> in the above equation (1.2b) represents the average optical path length (also called average optical path length) of the detected photons.
- ⁇ t> represents the center of gravity of the impulse response waveform (average time of flight of the detected photons), and the time waveform of the impulse response can be easily calculated by calculating (calculating the moment) with a computer. .
- the time waveform of the impulse response can be easily calculated by computing with a computer.
- the time integral I ( ⁇ S, ia) of ⁇ a related third floor partial derivative i.e. the optical path length average L (us, ⁇ Roh / / a 2 order partial derivative can be obtained regarding this
- the value gives information about the waveform distortion: Mathematically, if there is an m-order partial derivative, there is always a (m-1) th or lower partial derivative.
- the time width of the incident light pulse used for measurement is finite, and the bandwidth of the amplifier and the counting circuit is also finite. Therefore, the time waveform (observed waveform or observed value) obtained by actual measurement is a convolution of the impulse response of the scattering medium and the impulse response of the measurement system (also called instrument function).
- the following two methods are available to remove the influence of the characteristics of the measurement device from the observed values and obtain the average optical path length and dispersion of the impulse response of a true scattering medium.
- the first is the well-known deconvolution method.
- the impulse response is obtained by deconvolution of the observed value with the device function, and the optical path length average and dispersion are obtained from the obtained waveform.
- the second method the average and dispersion of the optical path length in the device function and the average and dispersion of the optical path length in the observation waveform are separately obtained, and the average and dispersion of the impulse response of the scattering medium are determined from these values.
- the average optical path length and the variance in the impulse response are the differences between the observed waveform and the instrument function.
- the observed waveform o (t) is calculated using the impulse response of the medium (true optical waveform) h (t) and the impulse response of the measurement system (instrument function) i (t).
- R and X are a real part and an imaginary part, respectively, and A and 0 are an amplitude and a phase delay, respectively, which can be easily measured by a lock-in amplifier or the like.
- Equation (3.3) is similar to equation (1.2c) above, and the left side of equation (3.3) is observable.
- the integrand of the first term on the right side is a group delay, which corresponds to the optical path length average L (js, jUa) described above.
- Equation (3.3) 2-i ⁇ .
- / ⁇ is a phase delay
- the change in the absorption coefficient when the scattering coefficient is constant (absorption coefficient difference) must be calculated from the measured group delay and its dependence on the absorption coefficient. Can be.
- the spectroscopic measurement method for quantifying the concentration of the absorption component from the optical path length average and dispersion values of the impulse response
- the transport scattering coefficient ⁇ 's two (1-g) / s ), which is generally easy to measure, is used.
- one type of water containing absorbing component considered two wavelengths spectroscopy of scattering media mainly, the example i Oyobie 2 wavelengths used for measurement, the optical in that its wavelength Constants are represented using subscripts 1 and 2.
- £ 1 and £ 2 are the wavelengths i and the extinction coefficient (or absorption coefficient) per unit concentration of the absorption component in the person 2 , for example, the molar extinction coefficients, ⁇ wl and ⁇ w2 are the wavelengths i and 2 Is the absorption coefficient of water. Therefore, seeking absorption coefficient difference obtained et al is from the measured waveform (a2 - ⁇ al), it is possible to quantify the concentration C of the absorptive constituent.
- the value of the scattering coefficient at two wavelengths differs in a general medium. This difference in the scattering coefficient complicates the algorithm for determining the concentration of the absorbed component.
- the relationship between the average optical path length and the transport scattering coefficient is first determined, and then a new method for quantifying the concentration of the absorption component using the relationship is described.
- the average optical path length L (z's, ju.) In the case of reflection measurement is simply abbreviated as L P ,
- / O is the distance between the light incidence and the detection position.
- Equation (4.3) is the effective attenuation coefficient ⁇ . ) 2 (.
- ⁇ e is the effective attenuation coefficient ⁇ . ) 2 (.
- Typical measurement conditions namely / O> 20 mm, ⁇ 's> 0. 8 mm, ⁇ a "0. 00 l
- Equation (4.3) is Is approximated.
- the ratio of the optical path length averages does not depend on the absorption coefficient, but becomes a constant determined by the transport scattering coefficient ratio.
- L shown in equation (4.3) It is difficult to measure the ratio directly.
- L l (a J (, / 1 ⁇ 2) I f ⁇ 'sl and define by k'.
- Li (ia) and L 2 (// a) used here have different transport scattering coefficients. It represents the average optical path length for a medium with the same absorption coefficient / a. Therefore, using the coefficient k 'defined here, the absorption coefficient has the same value ⁇ a, It is possible to estimate the ratio of the average optical path length for media with different transport scattering coefficients.
- equation (4.6) means that the curves k'X Li (a) and L 2 (// a) representing the average optical path length overlap in the (a, L) plane. From the curves Li (// a) and L 2 (j) representing the average optical path length at ⁇ a 2 ( ⁇ -'sl, // a) and 2 ( ⁇ 's 2, // a) against Holds.
- the concentration C of the absorption component is determined using such a relationship.
- the absorption coefficient difference is the optical path length average L, ( ⁇ al ) obtained from the actual measurement
- phase modulation measurement method (PMS method)
- the spectroscopic measurement method (MVS method) using the optical path length average and dispersion, or physical quantities equivalent to them, has the following advantages in addition to the advantages of the conventional MBL-based measurement method:
- the absolute value of the incident light intensity and individual differences do not matter, 2
- optical path length average L (z's,,) in the case of reflection measurement is given by the above formula (4.2), and if abbreviated as L,
- the transport scattering coefficient 's and the absorption coefficient can be quantified using the optical path length average L and the dispersion 2 calculated from the measured values.
- the method comprises biggest feature is simple 'and an advantage, a high accuracy is obtained for relatively large medium, this time transport scattering coefficient i' measurement accuracy of s and the absorption coefficient la is about 10% is there.
- this method has a transport scattering Excellent quantitative accuracy with respect to the ratio of numbers. That is, the above-described method enables the transport scattering coefficient ratio to be measured with high accuracy and high speed. In this case, the above-described difference calculation method can be used to obtain the optical path length average L and the dispersion 2 .
- the ratio 's (person 2) / HL's ( ⁇ ⁇ ) of the transport scattering coefficient obtained when measuring at wavelengths i and 2 is the average optical path length obtained at each wavelength.
- optical path length average and variance are abbreviated.
- the concentration C of the absorption component can be obtained from the measured value by substituting equation (5.6) into equation (4.8). If the transport scattering coefficient ratio is known in advance, this known value may be used. Further, the ratio of the transport scattering coefficient may be obtained by another method.
- FIG. 2 shows a measuring apparatus according to the present invention for quantifying the concentration C of the absorption component contained in the scattering medium 1 using light of two wavelengths.
- the liquid is, for example, water. You need to take care.
- the device shown in FIG. 2 includes a light guide 3 for light incidence, and an output end of the light guide 3 is arranged at a predetermined position on the surface of the scattering medium 1.
- a light source 5 is optically connected to the input end of the light guide 3 via a wavelength selector 4, and the pulse light emitted from the light source 5 is supplied to the wavelength selector 4 at a predetermined wavelength i and / or The wavelength is selected by 2 and is incident on the scattering medium 1 from the position U j via the light guide 3.
- the time width of this pulsed light may be short enough to derive the average optical path length of the impulse response from the light detection signal, and is usually selected in the range of about 10 ps to 1 ns.
- the wavelength of light is appropriately selected according to the scattering medium 1 to be measured. In general, for example, in a living body, the light wavelength is determined from the relationship between the transmittance of the living body and the spectroscopic absorption coefficient of the absorption component to be quantified. Usually, a wavelength in the near infrared region of about 700 to 900 nm is used.
- Various light sources such as a light emitting diode, a laser diode, and various pulse lasers can be used as the light source 5.
- the light source 5 may use two or more types of light sources that generate light of a single wavelength or a narrow band, but may also generate light of two or more wavelengths at the same time. With such a configuration of the light source 5, the configurations of the light guide 3 and the wavelength selector 4 are appropriately changed and set. Further, light having two or more wavelengths may be generated in time series. In this case, the wavelength selector 4 can be omitted.
- the device shown in FIG. 2 includes a light guide 6 for light detection, and the input end of the light guide 6 is arranged at a predetermined position on the surface of the scattering medium 1.
- a light detector 7 is optically connected to the output end of the light guide 6, and light propagated while being scattered inside the scattering medium 1 is transmitted from the position v k via the light guide 6. The light is guided to the detector 7, and the photodetector 7 converts the received light signal into a light detection signal which is an electric signal.
- a signal processing unit 8 is electrically connected to the photodetector ⁇ and the light source 5, and the signal processing unit 8 acquires waveform data indicating a temporal change in detected light intensity based on the photodetection signal.
- an arithmetic processing unit 9 is electrically connected to the signal processing unit 8.
- the arithmetic processing unit 9 calculates the average and dispersion of the optical path lengths of a plurality of photons constituting the detection light based on the waveform data. Based on the optical path length average, dispersion, and the ratio of the transport scattering coefficient at the two wavelengths, the difference in the absorption coefficient ( ⁇ a2 — ⁇ al ) is determined by the above equation (4.8). Based on the difference or directly, the concentration C of the absorbed component is determined by the above equation (4.9).
- the light guide for light incidence 3, the wavelength selector 4, and the light source 5 are the light incidence means according to the present invention, and the light guide 6 for light detection and the light detector 7 are the light detection means and signal processing according to the present invention.
- the unit 8 constitutes a signal processing unit according to the present invention.
- the arithmetic processing unit 9 is configured to have a plurality of functions, and these are the optical path length average and dispersion arithmetic means (or group delay and amplitude second-order partial differential value arithmetic means) according to the present invention; It constitutes the coefficient difference calculation means.
- the inside absorbs light and the outside blocks light. It is desirable to have a light-emitting structure.
- a wavelength selection filter (not shown) is appropriately arranged between the photodetector 7 and the light guide 6. The measurement may be performed.
- FIG. 3 shows an example of a preferred configuration of the photodetector 7, the signal processing unit 8, and the arithmetic processing unit 9.
- the configuration shown in Fig. 3 is for implementing a high-speed time waveform measurement method using a method called a so-called time-correlated photoelectron counting method.
- a photomultiplier tube (PMT) is used as the photodetector 7, and the signal processing unit 8 uses a constant 'fraction' discriminator (CFD) 21, time-amplitude conversion (TAC) 22 and AD converter (A / D) 23.
- CFD constant 'fraction' discriminator
- TAC time-amplitude conversion
- AD converter A / D
- This digital signal corresponds to waveform data indicating a temporal change of the detected light intensity.
- the CPU 30 is electrically connected to the light source 5 and the signal processing unit 8, and the timing of light detection synchronized with light incidence is controlled by the CPU 30.
- the waveform data output from the signal processing unit 8 is guided to the CPU 30.
- the wavelength of the incident light is also controlled or selected by the CPU 30.
- Specific wavelength selection means include, for example, an optical beam switch using a mirror, a wavelength switch using a filter, and an optical switch using an optical switch.
- the arithmetic processing unit 9 shown in FIG. 3 further includes a program memory 40 storing an operating system (OS) 41 and an internal information measurement program 42 described later in detail, and a data file storing various data files.
- An input device 70 having a keyboard 71 and a mouse 72 for receiving an input, and a display 81 for outputting the obtained display and an output device 80 having a pudding 82 are provided. These are also controlled by the CPU 30 which is electrically connected.
- the above memory may be a computer internal memory (hard disk) or a flexible disk.
- the data file memory 50 contains waveform data obtained by executing the internal information measurement program 42, optical path length average, instrument functions (impulse response of the measurement system), dispersion, transport scattering coefficient ratio, absorption coefficient difference, etc.
- the data is stored, and data such as measurement conditions and known values input in advance using the input device 70 are also stored.
- Such input data includes the shape of the medium to be measured, the light incident position, the light detection position, the distance between the light incident and the light detection positions, the wavelength of the light used for measurement, and the type of measurement (reflection type, transmission type, etc.). ), The absorption coefficient at a predetermined wavelength of the absorption component to be measured.
- the photodetector 7 includes a photomultiplier tube, a photodiode, and an avalanche chef. All types of photodetectors, such as photodiodes and PIN photodiodes, can be used. When selecting the photodetector 7 to be used for measurement, it is sufficient that the photodetector 7 has a spectral sensitivity characteristic that can detect light having the wavelength of the measurement light to be used. Further, when the optical signal is weak, it is preferable to use a photodetector with high sensitivity or high gain. Further, instead of the light guide 3 for light incidence and the light guide 6 for light detection, an optical fiber or a lens may be used.
- FIG. 4 the flowchart showing the processing of the internal information measuring program 42 shown in FIG. 3.
- pulse light of a predetermined wavelength generated by the light source 5 is incident on the light incident position u of the scattering medium 1 via the light guide 3 (SI 10),
- the light scattered and propagated inside the body 1 is detected by the light detector 7 via the light guide 6 installed at the light detection position v k (S120). .
- a light detection signal corresponding to the detected light is emitted from the light detector 7, and is converted into waveform data indicating a temporal change of the detected light intensity in the signal processing unit 8 (S130).
- the device function impulse response of the measurement system
- the device function is measured in advance (S 190), and is stored in the file memory 50.
- the device function is such that the scattering absorber 1 is removed in the configuration shown in FIG. 3, and the light output end of the light guide 3 and the light input end of the light guide 6 are directly opposed and contact-coupled. Measure. Therefore, the device function includes effects such as the pulse width of the light source and the bandwidth of the detection system.
- the optical path length average L and the dispersion 2 of a plurality of photons constituting the impulse response are calculated (S140).
- the average optical path length and variance of the impulse response are, as shown in Eqs. (2.8) and (2.10) above, the average optical path length between the measured waveform and the instrument function. And variance.
- the average optical path length is expressed by the weighted average of the time-resolved waveform, and the variance is expressed by the above (1.3). That is, the waveform data obtained above can be calculated by a computer (moment calculation) and can be obtained at high speed.
- the square root of the ratio of the scattering coefficients is calculated based on the equation (5.6) (S150).
- the difference of the absorption coefficient of the scattering medium or the concentration of the absorption component is calculated based on the above equation (4.8) or (4.9), respectively (S166 or S170). ), And outputs the calculated result (S180).
- the optical path length average and dispersion may be obtained from the impulse response obtained by performing deconvolution processing on the waveform data using the device function.
- the square root of the ratio of the scattering coefficient (S150) a value previously measured by another method may be used, as described above.
- n + 2 ( ⁇ 3, n is an integer of 1 or more) kinds of pulsed light or more as the light of the predetermined wavelength .n + 1 kinds of absorption coefficient differences are obtained. From these values, the concentrations of the n + 1 kinds of absorption components can be determined.
- This embodiment shows an example in which the present invention is applied to phase modulation measurement.
- the configuration of the measurement device is such that the signal processing unit 8 shown in FIG. 3 described above is replaced with an arithmetic device including, for example, a lock-in amplifier.
- the light source 5 has two types of predetermined wavelengths including three types of modulation frequency components ( ⁇ 1, ⁇ 2 , ⁇ 3 )! And / or ⁇ 2 modulated light is generated.
- FIG. 5 shows a flowchart of an embodiment in which the method of the present invention is applied to phase modulation measurement. In the flowchart shown in FIG.
- the intensity-modulated light of a predetermined wavelength generated by the light source 5 is incident on the light incident position Uj of the scattering medium 1 via the light guide 3 (S110), and the scattered light is absorbed.
- the light scattered and propagated inside the body 1 is detected by the light detector 7 via the light guide 6 installed at the light detection position v k (S120).
- a light detection signal corresponding to the detected light is emitted from the light detector 7 and supplied to the signal processing unit 8.
- the lock-in amplifier included in the signal processing unit 8 extracts three types of predetermined frequency component signals with respect to the modulated light of the wavelengths of the person i and the person 2 (S131), and also outputs three types of predetermined signals.
- the real part R, imaginary part X, amplitude A, and phase delay ⁇ described in Eq. (3.1) are output. Note that the zero point of the phase is obtained in advance (S191).
- the amplitude A, the phase delay, and the three modulation frequencies ( ⁇ ⁇ 5 ⁇ 2 , ⁇ ) of the three types of predetermined frequency component signals with respect to the two types of predetermined wavelength modulated light input are calculated.
- equal to the partial derivative with respect to absorption coefficient of second order partial differential multiple photons modulation frequency constitutes the detection light is omega 2 group delay, and for the amplitude of the logarithmic omega (group delay, (3. 5) Refer to the formula) is calculated (S141).
- the square root of the ratio of the scattering coefficient that is, k 'is calculated (S150).
- the absorption coefficient difference of the scattering medium or the concentration of the absorption component is calculated based on the above equation (4.8) or (4.9), respectively (S160 or S170). ), And output the calculated result (S180).
- the calculation is performed by replacing the average optical path length L with c times the group delay, and replacing the variance 2 with the second order partial derivative with respect to ⁇ of the logarithm of c 2 times the amplitude.
- the group delay and its partial differential value with respect to the absorption coefficient are obtained.
- the group delay is approximated to the phase delay.
- a partial differential value for the delay absorption coefficient may be calculated.
- a value previously measured by another method may be used.
- ⁇ + 1 kinds of absorption coefficient differences can be obtained. Then, from these values, the concentration of ⁇ + 1 absorption component can be quantified.
- FIG. 6 shows a third embodiment of the present invention and shows an apparatus for measuring or monitoring the concentration of hemoglobin or the oxygen saturation of hemoglobin in a scattering medium such as a human head.
- This device uses three types of wavelengths, wavelength input 2 and input 3 light.
- the operation principle is the same as that of the first embodiment when pulsed light is used, and the same operation principle as that of the second embodiment when modulated light is used.
- the structure of the container on which the light incident means and the light detection means are mounted is different from the above embodiments.
- the light incident means and the light detection means are contained in a container 10 having a mounting band attached to the head 1a like a headband, and a signal processing unit 8, an arithmetic processing
- the external device 11 including the unit 9 and the like is connected by a cable 12.
- FIG. 7 shows the details of the container 10.
- the container 10 contains a light source 5, a wavelength selector 4, a light guide for light incidence 3, a light guide for light detection 6, and a light detector 7, and has a predetermined wavelength emitted from the light source 5.
- the lights of e2 and e3 are wavelength-selected by the wavelength selector 4 and are incident on the head 1a via the light guide 3.
- the predetermined wavelengths 2 and 3 are appropriately selected with reference to the hemoglobin absorption spectrum shown in FIG.
- the container 10 containing the light incident means and the light detection means and the external device 11 containing the signal processing unit 8 and the arithmetic processing unit 9 are connected to the cable 12 via the connector 13.
- connection can be established by other means such as wireless or optical signals.
- connection can be established by other means such as wireless or optical signals.
- it is possible to measure not only at bedside or at rest, but also during exercise.
- it is possible to measure not only the head but also, for example, the thighs of people in marathons.
- connection is made with a city cable or optical cable, remote measurement of people at home from facilities such as hospitals is possible, and it can also be applied to centralized management of hospital rooms in hospitals and the like.
- C b molar concentration of reduced hemoglobin (M)
- M Molar concentration of oxidized hemoglobin (M)
- ⁇ ⁇ , . 3 sh + q 3 C. + ⁇ ⁇ .
- aa 2 and a 3 are absorption coefficients including water and absorption components other than hemoglobin. .
- the left side of the above equation is a quantity measured by the method of the present invention.
- This equation consists of two unknowns, C b and C.
- two unknowns C b and C are obtained.
- a standard value of a living body can be used for the values of aa 2 and a 3 .
- the concentration C b of reduced hemoglobin the concentration of Mo globin to the oxidation-type C. , The amount of hemoglobin (C b + C.), And the oxygen saturation C. / (C b + Co).
- Tables 1 and 2 show the measurement results when the distance between the light incidence and the detection position is 5 mm in the reflection type measurement, and Tables 3 and 4 show the measurement results when the distance between the light incidence and the detection position is 30 mm.
- ⁇ A in the leftmost column in each table is the absorption coefficient of the medium set in the Monte Carlo calculation.
- the ⁇ ⁇ & in the center of the table is calculated using the average of the optical path length L calculated from a pair of vertically adjacent Monte-Rurodé nights and the variance 2 as shown in the above equation (4.8).
- Absorption coefficient difference determined by However, k ' l'.
- the right portion of the table showed the absorption coefficient difference obtained by another method of quantifying the ratio of the transport scattering coefficients for comparison ((5. 3 a) formula) as 01d-A ⁇ a. From the table, this Old-A Za has a tendency that DC bias tends to be applied in the reflection type measurement, and the inclination tends to be larger than 1 in the transmission type measurement.
- a ⁇ a obtained by the method according to the present invention is 01d- / ⁇ ⁇ it can be seen that the error is small compared to a.
- Two picosecond pulse generators with z and a pulse width of about 50 ps were used. These picosecond pulses pass through an optical switch and an optical attenuator, enter a 200-m-diameter GI fiber, and the light emitted from the other end, the output end, enters a phantom, which is a scattering absorber. Is done.
- the output light from the phantom is received by a bundle fiber with a diameter of 5 mm and measured by the time-correlated photoelectron counting device shown in Fig. 3.
- the device functions at two wavelengths required for the calculation of the optical path length average and the like are measured in a state where the light incident and light detection fibers are in close contact.
- the phantom used in the experiment was prepared by placing 1% Intralipid solution as scattering substance in an acrylic resin container (width 120 mm, height 120 mm, depth 40 mm) at 4200 ml, and then grease was absorbed as an absorbing substance.
- the absorption coefficient of the actual phantom is the sum of the absorption coefficient of the added ink and the absorption coefficient of water (distilled water).
- the absorption coefficient of the greenish brown ink and the absorption coefficient of distilled water were measured with a spectrometer. Table 7 shows the optical parameters of the phantom in the experiment. Table 7
- Table 8 shows the optical path length average and dispersion values of the impulse response obtained from the experimental values obtained from the phantom experiment performed under the above conditions.
- Figure 9 shows the relationship between the phantom absorption coefficient and the average optical path length.
- the absorption coefficient of the phantom was calculated using the actually measured absorption coefficient of distilled water, the amount of added ink, and the actually measured absorption coefficient of the ink.
- the curve in the figure is the general form of the equation representing the average optical path length obtained by light diffusion approximation.
- Table 9 shows the concentrations C of the absorbed components determined by the experiment.
- the method and apparatus for measuring the internal information of a scattering medium according to the present invention is a method for measuring the internal information of a scattering medium, which enables more accurate and high-speed measurement than a conventional measuring method based on the MBL rule. It can also be used as a device for measuring the absorption coefficient of a scattering medium and the concentration of absorbing components.
- the measurement method and apparatus according to the present invention use the average and dispersion of optical path lengths or physical quantities corresponding thereto, and do not use information such as the absolute value or ratio of light intensity. Therefore, it is useful in that it solves a difficult problem in practical use of quantifying or estimating the absolute value of the amount of light incident on a medium.
- Such a method has the great advantage that it can perform real-time measurement and can perform measurement independent of measurement forms such as shape and boundary conditions, medium dimensions, scattering characteristics, distance between light incidence and detection position, transmission reflection, etc. I will have it together. From the above, it is expected that the method and apparatus for measuring the internal information of the scattering medium according to the present invention are widely applied to an apparatus for simply and non-invasively measuring various physiologically functional substances in a living body in real time.
Description
Claims
Priority Applications (4)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
EP99954411A EP1136811B1 (en) | 1998-11-05 | 1999-11-05 | Method and device for measuring internal information of scattering absorber |
DE69925930T DE69925930T2 (de) | 1998-11-05 | 1999-11-05 | Verfahren und vorrichtung zur messung der inneren eigenschaften eines streuenden absorbers |
AU10782/00A AU1078200A (en) | 1998-11-05 | 1999-11-05 | Method and device for measuring internal information of scattering absorber |
US09/848,252 US6704110B2 (en) | 1998-11-05 | 2001-05-04 | Method and apparatus for measuring internal information of scattering medium |
Applications Claiming Priority (2)
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JP10/314613 | 1998-11-05 | ||
JP31461398A JP3950243B2 (ja) | 1998-11-05 | 1998-11-05 | 散乱吸収体の内部情報の計測方法及び装置 |
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US09/848,252 Continuation-In-Part US6704110B2 (en) | 1998-11-05 | 2001-05-04 | Method and apparatus for measuring internal information of scattering medium |
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PCT/JP1999/006181 WO2000028302A1 (en) | 1998-11-05 | 1999-11-05 | Method and device for measuring internal information of scattering absorber |
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US (1) | US6704110B2 (ja) |
EP (1) | EP1136811B1 (ja) |
JP (1) | JP3950243B2 (ja) |
AU (1) | AU1078200A (ja) |
DE (1) | DE69925930T2 (ja) |
WO (1) | WO2000028302A1 (ja) |
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JP4499270B2 (ja) * | 2000-10-30 | 2010-07-07 | 浜松ホトニクス株式会社 | 散乱吸収体計測装置の校正方法、及びそれを用いた散乱吸収体計測装置 |
US7505135B2 (en) * | 2002-07-15 | 2009-03-17 | Ariel Ltd. | Method and apparatus for imaging through scattering or obstructing media |
JP2006032885A (ja) * | 2003-11-18 | 2006-02-02 | Sharp Corp | 光源装置およびそれを用いた光通信装置 |
US7551950B2 (en) * | 2004-06-29 | 2009-06-23 | O2 Medtech, Inc,. | Optical apparatus and method of use for non-invasive tomographic scan of biological tissues |
JP4662831B2 (ja) * | 2005-09-20 | 2011-03-30 | 富士フイルム株式会社 | 試料分析装置 |
JP5420163B2 (ja) * | 2007-10-24 | 2014-02-19 | 浜松ホトニクス株式会社 | 生体計測装置 |
JP5087526B2 (ja) * | 2008-11-25 | 2012-12-05 | 浜松ホトニクス株式会社 | 散乱吸収体計測方法及び散乱吸収体計測装置 |
US8788001B2 (en) * | 2009-09-21 | 2014-07-22 | Covidien Lp | Time-division multiplexing in a multi-wavelength photon density wave system |
US8391943B2 (en) * | 2010-03-31 | 2013-03-05 | Covidien Lp | Multi-wavelength photon density wave system using an optical switch |
US20140019077A1 (en) | 2011-03-28 | 2014-01-16 | Avl Test Systems, Inc. | Deconvolution method for emissions measurement |
DE102012101858A1 (de) * | 2012-03-06 | 2013-09-12 | MBE- Komponenten GmbH | Vorrichtung und Verfahren zur Bestimmung der Partialdrucke von Prozessstoffen |
JP6048950B2 (ja) * | 2012-06-15 | 2016-12-21 | セイコーエプソン株式会社 | 濃度測定装置 |
JP6043276B2 (ja) * | 2013-12-27 | 2016-12-14 | 浜松ホトニクス株式会社 | 散乱吸収体測定装置及び散乱吸収体測定方法 |
JP6551723B2 (ja) * | 2014-11-13 | 2019-07-31 | 株式会社リコー | 光学センサ、光学検査装置、及び光学特性検出方法 |
EP3315943B1 (en) | 2015-06-24 | 2020-03-11 | Hamamatsu Photonics K.K. | Scattering absorber measurement device and scattering absorber measurement method |
US11654635B2 (en) | 2019-04-18 | 2023-05-23 | The Research Foundation For Suny | Enhanced non-destructive testing in directed energy material processing |
Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPH07163571A (ja) * | 1993-09-08 | 1995-06-27 | Siemens Ag | 種々異なる波長の光による組織検査装置 |
JPH1073481A (ja) * | 1996-08-30 | 1998-03-17 | Hamamatsu Photonics Kk | 散乱体の吸収情報計測方法及び装置 |
JPH10111238A (ja) * | 1996-10-03 | 1998-04-28 | Technol Res Assoc Of Medical & Welfare Apparatus | 散乱体の吸収情報の計測方法及び装置 |
Family Cites Families (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5792051A (en) * | 1988-12-21 | 1998-08-11 | Non-Invasive Technology, Inc. | Optical probe for non-invasive monitoring of neural activity |
JP2780935B2 (ja) * | 1994-09-22 | 1998-07-30 | 浜松ホトニクス株式会社 | 散乱吸収体の吸収成分の濃度計測方法及び装置 |
DE4445683A1 (de) * | 1994-12-21 | 1996-06-27 | Boehringer Mannheim Gmbh | Verfahren zur Untersuchung eines streuenden Mediums mit intensitätsmoduliertem Licht |
JP3793255B2 (ja) | 1995-08-28 | 2006-07-05 | 浜松ホトニクス株式会社 | 光学測定方法及び光学測定装置 |
GB9702018D0 (en) * | 1997-01-31 | 1997-03-19 | Univ London | Determination of the ratio of optical absorbtion coefficients at different wavelengths in a scattering medium |
JP3887486B2 (ja) * | 1998-05-26 | 2007-02-28 | 浜松ホトニクス株式会社 | 散乱吸収体の内部特性分布の計測方法及び装置 |
-
1998
- 1998-11-05 JP JP31461398A patent/JP3950243B2/ja not_active Expired - Lifetime
-
1999
- 1999-11-05 DE DE69925930T patent/DE69925930T2/de not_active Expired - Lifetime
- 1999-11-05 AU AU10782/00A patent/AU1078200A/en not_active Abandoned
- 1999-11-05 EP EP99954411A patent/EP1136811B1/en not_active Expired - Lifetime
- 1999-11-05 WO PCT/JP1999/006181 patent/WO2000028302A1/ja active IP Right Grant
-
2001
- 2001-05-04 US US09/848,252 patent/US6704110B2/en not_active Expired - Lifetime
Patent Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPH07163571A (ja) * | 1993-09-08 | 1995-06-27 | Siemens Ag | 種々異なる波長の光による組織検査装置 |
JPH1073481A (ja) * | 1996-08-30 | 1998-03-17 | Hamamatsu Photonics Kk | 散乱体の吸収情報計測方法及び装置 |
JPH10111238A (ja) * | 1996-10-03 | 1998-04-28 | Technol Res Assoc Of Medical & Welfare Apparatus | 散乱体の吸収情報の計測方法及び装置 |
Non-Patent Citations (2)
Title |
---|
See also references of EP1136811A4 * |
ZHANG H, ET AL.: "QUANTITATION OF ABSORBERS IN TURBID MEDIA USING TIME-INTEGRATED SPECTROSCOPY BASED ON MICROSCOPIC BEER-LAMBERT LAW", JAPANESE JOURNAL OF APPLIED PHYSICS, JAPAN SOCIETY OF APPLIED PHYSICS, JP, vol. 37, no. 05A, PART 01, 1 January 1998 (1998-01-01), JP, pages 2724 - 2727, XP002924572, ISSN: 0021-4922, DOI: 10.1143/JJAP.37.2724 * |
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Publication number | Publication date |
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EP1136811B1 (en) | 2005-06-22 |
JP2000146828A (ja) | 2000-05-26 |
EP1136811A4 (en) | 2003-01-02 |
DE69925930T2 (de) | 2006-05-11 |
US20010038454A1 (en) | 2001-11-08 |
US6704110B2 (en) | 2004-03-09 |
DE69925930D1 (de) | 2005-07-28 |
JP3950243B2 (ja) | 2007-07-25 |
EP1136811A1 (en) | 2001-09-26 |
AU1078200A (en) | 2000-05-29 |
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