JP2010125260A - Biological testing apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a biological testing apparatus which makes a living tissue minimize to attenuate a light intensity and an elastic wave, can irradiate an object at a high efficiency with light energy below MPE, and can detect an elastic wave in a high S/N ratio. <P>SOLUTION: The biological testing apparatus includes: a light source for generating light to irradiate an object; an elastic wave detecting means for detecting an elastic wave generated by the object that has absorbed the irradiated light; and a sound adjusting layer which is set to have one surface touching with the elastic wave detecting means and another one contacting with the object, wherein the apparatus is designed to allow the light to pass through the sound adjusting layer and then irradiate the object, and further is designed to have a light diffusing means for irradiating the object with light almost the same intensity independently of the position inside the sound adjusting layer. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a biopsy device for measuring spectral characteristics inside a living tissue, and particularly to a reflection-type biopsy device using a photoacoustic effect.

A biopsy device that measures the spectral characteristics inside living tissue is diagnosed by determining the formation of new blood vessels associated with tumor growth and oxygen metabolism of hemoglobin from the light absorption characteristics of specific substances such as hemoglobin contained in blood. It is used for.
Such an apparatus uses near infrared light having a wavelength of about 600 to 1500 nm, which has good transmission characteristics for living tissue.
However, the light transmitted through the living tissue propagates while repeating strong scattering by cells of several tens of μm size constituting the living body, and thus becomes multiple scattered light (diffused light).
With this diffused light, it is difficult to obtain local spectral characteristics in the living tissue because all the paths through which the light has propagated cannot be specified.
For this reason, in a conventional biopsy apparatus, an apparatus using a photoacoustic effect has been developed as a method for measuring local spectral characteristics in a living tissue.

  As a reflection-type biological examination apparatus using the photoacoustic effect as described above, for example, a pulsed light is irradiated into a living tissue, and a local region is detected from an elastic wave generated by a photoacoustic effect generated based on optical energy. An apparatus for measuring spectral characteristics has been proposed (see, for example, Patent Document 1).

Further, as a reflection-type biological examination apparatus using the photoacoustic effect, Patent Document 2 proposes the following biological information video apparatus.
This device is configured to alternately arrange optical fibers that irradiate light on living tissue and piezoelectric elements that detect elastic waves, or to detect photoacoustic waves using transparent piezoelectric elements that can transmit the irradiating light. Is done.
Then, the living tissue is irradiated with light from a probe in contact with the surface of the subject, and an elastic wave is detected from the same probe.
In such a reflection type measurement device, there is no restriction that the subject is arranged between the light irradiation unit and the elastic wave detection unit unlike the transmission type measurement device, so that it can be applied to many measurement objects. It becomes possible.
US Pat. No. 5,843,0023 JP 2005-21380 A

However, the conventional reflection-type biopsy device that measures the spectral characteristics inside the living tissue has the following problems.
The intensity of light irradiated into the living tissue is significantly attenuated by absorption and scattering in the process of propagating through the living tissue.
In addition, the elastic wave generated based on the light energy applied to the inside of the living tissue also attenuates the signal intensity due to the influence of absorption and scattering in the process of propagating through the living tissue.
In order to cope with these, it is conceivable to increase the generated elastic wave by increasing the light energy irradiated into the living tissue.
However, a maximum permissible exposure (MPE) that can irradiate the living body in order to prevent damage to the living body that is the subject by the light energy to be irradiated (hereinafter, abbreviated as MPE). To do).
Therefore, even if the light energy to be irradiated is increased, the MPE becomes the upper limit.
The MPE is determined by the following criteria, for example.
(1) IEC 60825-1: Safety of laser products
(2) JIS C 6802: Safety standard for laser products (3) FDA: 21 CFR Part 1040.10
(4) ANSI Z136.1: Laser Safety Standards
Thus, since the light energy irradiated beyond MPE cannot be increased, it is desirable to minimize the attenuation of the light intensity and the elastic wave by the living tissue.
When measuring an object in a reflection type, the propagation distance of both the light and the elastic wave is minimized by matching the position of the opening where the light enters the target site and the position of the detection unit that detects the elastic wave generated from the target site. By doing so, attenuation of light intensity and elastic wave can be minimized.

However, in the devices shown in Patent Document 1 and Patent Document 2, the positions where the optical fiber as the opening for entering light into the living tissue and the piezoelectric element as the detection unit for detecting the elastic wave are not aligned. .
For this reason, the light intensity and the attenuation of the elastic wave by the living tissue increase, and there is a problem that the elastic wave cannot be detected with a high S / N.
Further, in the probe using a transparent piezoelectric element and an optical fiber that can transmit the light to be irradiated shown in Patent Document 2, the position of the opening for incident light and the position of the detection unit for detecting the elastic wave coincide with each other. Since it is comprised, attenuation of light intensity and an elastic wave can be reduced.
However, in such a configuration, light is not irradiated from the surface of the living body in the vicinity of the region where the optical fiber is not disposed.
Since MPE is light energy that can be irradiated per unit area, if there is a non-irradiated region, the incident light energy is reduced and an elastic wave cannot be detected with high S / N.
Although it is possible to reduce the non-irradiation area by arranging optical fibers at high density, in this case, the bundle of optical fibers becomes thick and the probe becomes difficult to handle.

Moreover, in the probe using the transparent piezoelectric element and single lens which can transmit the light to irradiate shown by patent document 2, the intensity | strength of the light which injects into a biological body is high near the center of a lens, and becomes low in a peripheral part. .
For this reason, there is a problem in that an elastic wave cannot be detected with a high S / N because light energy incident on the living body is reduced from a region where the light intensity is low.
In addition, since the piezoelectric element disclosed in Patent Document 2 requires a characteristic capable of transmitting irradiated light, usable materials are limited to some materials such as PZNT.
The frequency characteristics of the piezoelectric element are determined by the material characteristics of the piezoelectric element and the thickness of the element.
For example, a polymer piezoelectric film material such as PVDF (polyvinylidene fluoride), which is relatively easy to fabricate, is used in a frequency band of several tens of MHz or more.
In addition, piezoelectric ceramic materials such as PZT (lead zirconate titanate), which can easily manufacture thick elements of several mm or more, are used in the frequency band from kHz to 10 MHz.
The frequency band required for the measuring device is selected according to the depth of the target tissue and the required resolution.
Limiting the material that can be used for the piezoelectric element as in Patent Document 2 has a problem of limiting the target tissue and application.
Further, neither Patent Document 1 nor Patent Document 2 discloses monitoring or controlling so that the intensity of light applied to the subject does not exceed MPE.

  In view of the above problems, the present invention minimizes light intensity and elastic wave attenuation caused by living tissue, and can irradiate a subject with light energy that does not exceed MPE with high efficiency and elasticity at high S / N. An object of the present invention is to provide a biopsy apparatus that can detect waves.

The present invention provides a biopsy device configured as follows.
The biopsy apparatus of the present invention includes a light source that generates light for irradiating a subject,
An acoustic wave detection unit that detects an elastic wave generated by the subject that has absorbed the irradiated light, and an acoustic matching layer that is provided in contact with the elastic wave detection unit on one side and that can contact the subject on the other side A biopsy device comprising:
The light is configured to be able to irradiate the subject via the acoustic matching layer,
It has a light diffusing means for irradiating light with substantially uniform intensity regardless of the position in the acoustic matching layer.
The biological examination apparatus of the present invention is characterized by having a light guide means for guiding the light generated by the light source to the acoustic matching layer.
The biopsy device of the present invention is characterized in that the light diffusing means is constituted by a light diffusing member provided in the acoustic matching layer.
In the living body examination apparatus of the present invention, the light diffusing means changes the intensity of light to be irradiated by changing the distribution density or size of the light scatterer.
In the living body examination apparatus of the present invention, the light scattering member is constituted by light scattering particles or stippling.
In the biopsy device of the present invention, the member constituting the elastic wave detecting means is constituted by a member that transmits light,
The light diffusing means includes a lens array disposed between the light source and the elastic wave detecting means.
In addition, the biopsy device of the present invention includes a reference member that serves as a reference as to whether or not the light intensity applied to the subject is within a maximum allowable range allowed for the subject. And
In the biopsy device of the present invention, the reference member is provided on the acoustic matching layer or a cap member in contact with the acoustic matching layer, and the light intensity of the light guided to the reference member is allowed to the subject. And a control device for controlling so as not to exceed a maximum allowable range.
The biopsy device of the present invention is characterized in that the reference member is made of a material having the same acoustic impedance as that of the acoustic matching layer.
The biopsy device of the present invention is characterized in that the cap member is made of a material having the same acoustic impedance as that of the reference member and the acoustic matching layer.
The biological examination apparatus of the present invention further includes an ultrasonic generator, and the elastic wave detecting means is generated in the subject by the ultrasonic wave generated from the ultrasonic generator and applied to the subject. It is characterized in that the generated echo can be detected.
In the living body inspection apparatus of the present invention, the ultrasonic generator is also used by the elastic wave detecting means.

  According to the present invention, attenuation of light intensity and elastic waves by living tissue can be minimized, light energy not exceeding MPE can be irradiated to a subject with high efficiency, and elastic waves can be detected with high S / N. A possible biopsy device can be realized.

  The best mode for carrying out the present invention will be described by the following examples.

Examples of the present invention will be described below.
[Example 1]
In the first embodiment, a configuration example of a reflective biopsy apparatus to which the present invention is applied will be described.
FIG. 1 is a schematic diagram illustrating the configuration of a reflection-type biopsy apparatus according to the present embodiment.
In FIG. 1, 100 is a light generator, 200 is an ultrasonic detector, 300 is an illumination optical system, 400 is a signal analysis device, 500 is a control device, 600 is a memory, 700 is a display, 800 is a main body housing, and 900 is A probe housing, 1000 is a cable.
E is a subject, and α is an absorber inside the living tissue.
The light generator 100 and the signal analysis device 400 are housed in a main body housing 800, and the ultrasonic detector 200 and the illumination optical system 300 are housed in a probe housing 900.
The cable 1000 connects the main body housing 800 and the probe housing 900.
The subject E here is, for example, a living tissue such as a breast.

The biological examination apparatus of the present embodiment includes a light source (light generator 100) that generates light for irradiating a subject,
Elastic wave detection means (piezoelectric element 6) for detecting elastic waves generated by the subject that has absorbed the irradiated light;
An acoustic matching layer 5 provided on one surface in contact with the elastic wave detecting means and capable of contacting the subject on the other surface.
The light can be irradiated to the subject via the acoustic matching layer 5.
In the present specification, an acoustic wave generated by the photoacoustic effect is referred to as a photoacoustic wave, and an acoustic signal is obtained by converting the photoacoustic wave into an electric signal by the piezoelectric element 6.

Next, schematic steps in the measurement method for measuring the subject E with the biopsy apparatus having the configuration of the above-described embodiment will be described.
The light generator 100 emits nanosecond-order pulsed light, and the illumination optical system 300 guides the pulsed light to the surface of the subject E.
The pulsed light incident from the surface of the subject E propagates inside the living tissue and reaches the absorber α.
The light energy that has reached the absorber α is absorbed and converted into thermal energy, an instantaneous temperature rise occurs in the absorber α, and the increased temperature is relaxed.
At this time, expansion and contraction occur in the tissue containing the absorber α due to the temperature rise and relaxation, thereby generating an elastic wave that becomes a photoacoustic wave.
The elastic wave generated from the absorber α propagates through the tissue of the subject E and is detected by the ultrasonic detector 200.
The detected elastic wave is converted into an electric signal by the ultrasonic detector 200 to be an acoustic signal. The signal analysis device 400 calculates the position of the absorber α from the time characteristic of the acoustic signal, and calculates the absorption coefficient μ _a from the intensity characteristic.
Furthermore, by reconstructing the spatial distribution of the absorption coefficient mu _a surrounding absorber α and to produce an image of the absorption characteristic in the specimen E.
The control device 500 stores the calculated position and the absorption coefficient μ _a in the memory 600 and displays a spatial distribution image of the absorption coefficient μ _a on the display 700.

Next, details of each component will be described.
It is known that when a tumor such as cancer grows in a living tissue, the formation of new blood vessels and the consumption of oxygen increase.
As a method for evaluating the formation of new blood vessels and the increase in oxygen consumption, characteristics of absorption spectra of oxygenated hemoglobin (HbO ₂ ) and reduced hemoglobin (Hb) can be used.
FIG. 2 is an absorption spectrum of HbO ₂ and Hb in the wavelength range of 600 to 1000 nm.
The biopsy apparatus measures the concentrations of Hb and HbO ₂ contained in the blood in the living tissue from the absorption spectra of multiple wavelengths of HbO ₂ and Hb.
Then, by measuring the concentration of Hb and HbO ₂ at a plurality of positions and creating an image of the concentration distribution, it is possible to determine the region where the new blood vessels are formed in the living tissue.
Further, the oxygen saturation can be calculated from the concentrations of Hb and HbO ₂ , and the region where the oxygen consumption is increasing can be determined from the oxygen saturation.
Thus, the spectral information of Hb and HbO ₂ measured by the biopsy device can be used for diagnosis.

The light generator 100 is a light source that emits nanosecond-order pulsed light of a specific wavelength that irradiates the subject E, and includes a laser 1, a laser driver 2, and a pulse generator 3.
The wavelength of the light emitted by the laser 1 is selected according to the absorption spectrum of water, fat, protein, oxidized hemoglobin, reduced hemoglobin, etc. constituting the living tissue.
As an example, the range of 600 to 1500 nm is suitable because it absorbs water, which is the main component of the internal tissue of the living body, and transmits light well, and is characterized by the spectra of fat, oxyhemoglobin, and reduced hemoglobin.
In this embodiment, as shown in FIG. 2, _two wavelengths of λ1 = 700 nm and λ2 = 850 nm are used as wavelengths around 800 nm at which the absorption characteristics of Hb and HbO ₂ are switched.
As a specific example of the light source, a semiconductor laser that generates different wavelengths, a wavelength tunable laser, or the like may be used.

The ultrasonic detector 200 detects elastic waves generated inside the subject E.
FIG. 3 shows a structure of a linear array probe as an example of an ultrasonic detector constituting the living body inspection apparatus in the present embodiment.
In FIG. 3, 4 is an acoustic lens, 5 is an acoustic matching layer, 6 is a plurality of piezoelectric elements, 7 is a backing material, and 8 is a lead wire.
The linear array probe of the present embodiment is configured by providing an acoustic lens 4 in contact with the surface of the subject E, and providing an acoustic matching layer 5 on the opposite side of the acoustic lens 4 to the subject E.
Further, a plurality of small strip-shaped piezoelectric elements 6 a, 6 b, 6 c, 6 d, 6 e, 6 f, 6 g are arranged in a straight line so as to contact the acoustic matching layer 5, and a backing material 7 is further provided.
Lead wires 8a, 8b, 8c, 8d, 8e, 8f and 8g are connected to each piezoelectric element 6.

The acoustic lens 4 uses a cylindrical lens that focuses in a direction perpendicular to the arrangement direction of the piezoelectric elements 6, and selectively receives a photoacoustic signal generated from a focal position inside the living tissue.
The material constituting the acoustic lens is preferably a material having acoustic characteristics similar to that of a living tissue, and examples thereof include silicon rubber.
If it is made of a material having a sound velocity slower than the sound velocity inside the living tissue, the shape becomes a convex lens, the focal position is determined by the curvature of the convex surface, and the focal size is determined by the focal length and the width of the cylindrical lens.
On the other hand, as a method of focusing in the arrangement direction of the piezoelectric elements 6, electronic focusing using a linear array probe is used. The electronic focus will be described later.

The acoustic matching layer 5 is provided in order to efficiently transmit elastic waves.
In general, the acoustic impedance of a piezoelectric element material and a living body are greatly different. Therefore, when the piezoelectric element material and a living body are in direct contact with each other, reflection at the interface is increased and elastic waves cannot be efficiently transmitted.
Therefore, the acoustic wave is efficiently transmitted by inserting the acoustic matching layer 5 made of a substance having an intermediate acoustic impedance between the piezoelectric element material and the living body.
Examples of the material constituting the acoustic matching layer 5 include epoxy resin and quartz glass.
In the present invention, the acoustic lens 4 and the acoustic matching layer 5 are commonly used as constituent members of the illumination optical system 300, and the functions of these illumination optical systems 300 will be described later.

The piezoelectric element 6 is an elastic wave detecting means for converting an elastic wave (pressure) generated by a subject that has absorbed light irradiated from the light generator 100 into an acoustic signal that is an electric signal (voltage). .
The material of the piezoelectric element 5 is selected according to the measurement depth of the subject E and the required resolution.
Examples include a piezoelectric ceramic material typified by PZT (lead zirconate titanate) and a polymer piezoelectric film material typified by PVDF (polyvinylidene fluoride) suitable for detecting photoacoustic signals of 1 MHz to several tens of MHz. Can be used.
The backing material 7 is for suppressing unnecessary vibration of the piezoelectric element 6 that has received elastic waves.

Next, electronic focusing using the linear array probe of this embodiment will be described.
FIG. 4 is a diagram for explaining the electronic focus.
In FIG. 4, 9 is a variable delay element, and 10 is a receiver.
A variable delay element 9a, b, c, d, e, f, g and a receiver 10 are connected to a plurality of piezoelectric elements 6a, b, c, d, e, f, g, and a receiver 10 via lead wires 8, respectively. Connected.
The variable delay element 9 is a device that delays the conduction of an electric signal transmitted through the electric wire using a coil obtained by winding an elongated electric wire in a coil shape.
Moreover, the delay time of an electrical signal can be adjusted by switching a plurality of taps provided in the middle of the coil.
The receiver 10 is a device that receives an acoustic signal converted by the piezoelectric element 6.

The elastic waves generated from the position X of the elastic wave generation source reach the piezoelectric element 6 with time differences τa, τb, τc, τd, τe, τf, and τg, respectively.
The elastic wave that has reached the piezoelectric element 6 is converted into an acoustic signal and is received by the receiver 10 through the variable delay element 9.
At this time, the difference in distance between the position X of the elastic wave generating source and each piezoelectric element 6 can be corrected by the variable delay element 9 to make the phases uniform.
In the example shown in the figure, the delay time given by the variable delay element 9 is increased for the piezoelectric element 6 that has a short distance from the position X and reaches the elastic wave earlier.
In addition, when the piezoelectric elements that are equidistant from the position X have the same delay time given by the variable delay element 9 (τa = τg <τb = τf <τc = τe <τd), the phase when the receiver 10 receives the signal is changed. Can be matched.
As described above, the electronic focus of the linear array probe can control the focal length and the focal position in the arrangement direction of the piezoelectric elements 6 by controlling the delay time given by the variable delay element 9.
In the above example, the phase is corrected by electronic focusing using the variable delay element 9.
However, a signal at a desired position can also be acquired from a plurality of acoustic signals acquired from the plurality of piezoelectric elements 6 without using the variable delay element 9 by using the Sum And Delay Beamforming method.

As another configuration example of the ultrasonic detector 200, a configuration example of a 2D array probe will be described.
FIG. 5 shows the structure of a 2D array probe which is another configuration example of the ultrasonic detector 200 of the present embodiment.
Members having the same numbers as those in FIG. 3 have the same functions as those described above.
In the linear array probe described above, the electronic focus is used only for the method of focusing in the arrangement direction of the piezoelectric elements 6, whereas in the 2D array probe, the electronic focus is set in all directions in which the piezoelectric elements 6 are arranged. Can be used.
Further, by using the Sum And Delay Beamforming method from a plurality of acoustic signals acquired from the plurality of piezoelectric elements 6, signals at desired positions in all directions can be acquired.
In this embodiment, the acoustic matching layer 5 and the acoustic lens 4 are used. However, in the case of the 2D array probe described with reference to FIG. is there.
In addition, the acoustic matching layer 5 may be composed of multiple layers when acoustic matching between the subject and the piezoelectric element is performed in a plurality of stages.
Furthermore, a protective layer may be provided with a thickness and material that does not significantly deteriorate the elastic wave in order to protect the contact portion with the subject.
As described above, the acoustic matching layer in the present specification is a layer structure provided between the piezoelectric element 6 and the subject E, and in addition to the acoustic matching layer 5, the acoustic lens 4 and the multilayer acoustic matching layer. Including a protective layer.

The illumination optical system 300 of this example guides light to the subject E.
The acoustic matching layer 5 and the acoustic lens 4, which are components common to the ultrasonic detector 200 described above, and an optical fiber 11 (light guiding means) that guides pulsed light from the light source are housed in the probe housing 900. This constitutes the probe of the biological examination apparatus.
The acoustic matching layer composed of the acoustic matching layer 5 and the acoustic lens 4 is provided so as to be in contact with the piezoelectric element 6 as the elastic wave detecting means described above on one side and to be in contact with the subject E on the other side. ing.
FIG. 6 is a schematic diagram illustrating the configuration of the probe of the biopsy apparatus in the present embodiment.
As described above, the acoustic lens 4 and the acoustic matching layer 5 are also commonly used as components of the ultrasonic detector 200.
Here, functions of the acoustic lens 4 and the acoustic matching layer 5 as components of the illumination optical system 300 will be described.
The acoustic matching layer 5 is a flat element that transmits light emitted from the laser 1 and is doped with light diffusing particles (light diffusing member) in order to form light diffusing means.
It is manufactured by mixing scattering particles with the epoxy resin described above. The optical fiber 11 guides the light emitted from the laser 1 to the side surface of the acoustic matching layer 5 as illustrated.
The light incident on the inside of the acoustic matching layer 5 is multiply scattered by the light scattering particles, and the entire acoustic matching layer 5 functions as a surface light source.
At that time, the spatial distribution of the light intensity in the entire region emitted from the acoustic matching layer 5 is adjusted so as to be a light distribution with a substantially uniform intensity.
Since the subject cannot be irradiated with light having an intensity exceeding the MPE even in a part of the area, a substantially uniform light distribution is formed, and the light intensity at this time is changed to the MPE. In addition, light energy that does not exceed MPE can be irradiated with high efficiency.
Adjustment for forming such a light distribution with substantially uniform intensity can be performed by changing the distribution density of the light scattering particles in accordance with the position of the acoustic matching layer 5.
For example, the intensity of the light transmitted through the light scattering member is attenuated as the propagation distance becomes longer. Therefore, the distribution density of the light scattering particles in the vicinity of the optical fiber 11 on which the light is incident is lowered. The distribution density is changed so as to increase the distribution density.

As a configuration example of the flat acoustic matching layer 5 including the light diffusing means, another configuration example that functions as a surface light source that emits substantially uniform light intensity will be described.
FIG. 7 is a diagram illustrating another configuration example of the flat acoustic matching layer 5. As an example of such a configuration, as shown in FIG. 7, a stipple made of a diffuse reflection material is provided on the surface on the side where the piezoelectric element 6 of a flat plate element made of a material that transmits light emitted from the laser 1 is placed. May be provided.
In this case, by changing the size of stippling and the distribution density according to the position of the acoustic matching layer 5, it can be adjusted so as to obtain a substantially uniform light intensity distribution.
The acoustic lens 4 is made of a material that transmits the light emitted from the laser 1, and guides the light emitted from the acoustic matching layer 5 to the surface of the subject E.

FIG. 8 shows another configuration example of the illumination optical system 300 (probe) provided with the light diffusing means.
In the example of FIG. 8, light diffusing particles are provided in the acoustic lens 4, and light emitted from the laser 1 is guided from the optical fiber 11 provided between the piezoelectric elements 6.
The probe using the illumination optical system 300 illustrated in FIGS. 6 and 8 is easy to handle because the cable does not become thick.
In addition, the piezoelectric element material can be selected from a large number of materials because there is no need to worry about light transmission characteristics.

FIG. 9 shows still another configuration example of the illumination optical system 300 (probe) provided with the light diffusing means.
In the example of FIG. 9, the acoustic lens 4 and the acoustic matching layer 5 in the acoustic signal detection unit are configured by members that transmit light of a specific wavelength emitted by the laser 1.
Further, the light diffusing means includes a lens array 14 that spreads light emitted from the optical fiber 11 disposed between the acoustic signal detecting means including the piezoelectric element 6 and the backing material 7 and the light source means.
FIG. 10 shows the light intensity distribution applied to the subject E. The solid line profile shows the light intensity distribution on the surface of the subject E, and the dotted line profile shows the light intensity distribution by each lens array 14. ing.
The profile of one lens in the lens array 14 is a distribution having a peak at the center of the lens, but the profile of each lens is adjusted on the surface of the subject E to be adjusted to a substantially uniform light intensity I distribution. can do.

The signal analysis apparatus 400 according to the present embodiment includes a calculation processing unit 12 and an image generation unit 13.
The calculation processing unit 12 calculates the position of the absorber α from the time characteristic of the acquired acoustic signal, and calculates the absorption coefficient μ _a from the intensity characteristic.
FIG. 11 is a profile of an acoustic signal obtained by measuring the subject E.
The acoustic signal generated from the subject E is acquired as a characteristic spike-like waveform generated from the interface between the surface of the subject E and the acoustic lens 4 and the absorber α.
The propagation time tx of the elastic wave converted into the acoustic signal from the waveform of the acoustic lens interface and the absorber α is known.
If the speed of sound in the biological tissue is vs, the distance between the surface of the subject E and the absorber α when measured can be calculated.
That is, spatial position information of the absorber α in the subject E can be obtained.
Further, the amplitude ΔP of the N-shaped spike shape generated from the absorber α represents the intensity Pα of the elastic wave generated from the absorber α.
The intensity Pα of the elastic wave due to the photoacoustic effect generated in the absorber α is the absorption coefficient of the absorber α μ _a , the light intensity incident on the absorber α is Iα, and the Gruneisen parameter determined according to the living tissue is Γ. Then, it can be calculated by the following formula.

As in the equation, when the intensity Iα of light incident on the absorber α changes, the intensity Pα of the elastic wave due to the photoacoustic effect changes.
This is because, in the case where there is a partial spot in the intensity distribution of the light incident on the subject, whether the intensity Pα of the detected elastic wave changes is due to the spot of the light intensity, or the absorber α to distinguish whether is intended by the absorption coefficient mu _a show that difficult.
For this reason, it is necessary to form a light distribution with a substantially uniform intensity and irradiate the subject with light so that the detected intensity Pα of the elastic wave is not caused by light intensity spots. .
In this way, irradiating the subject with light having a substantially uniform light distribution not only irradiates the subject with light energy not exceeding MPE with high efficiency, but also the elasticity generated in the absorber α. It is also necessary to calculate the absorption coefficient μ _a with high accuracy from the wave intensity Pα.

Since the intensity of light propagating in an absorbing / scattering medium such as a biological tissue can be calculated by using a light diffusion equation or a transport equation, Iα can be calculated.
ΔP measured by the ultrasonic detector 200 includes the influence of attenuation caused by propagation of the elastic wave generated in the absorber α through the living tissue. Therefore, Pα can be calculated by subtracting the influence of attenuation by calculation. it can.
From the above, the absorption coefficient μ _a of the absorber α in the subject E can be calculated.

Image generating unit 13, calculated based on the spatial position of the absorption coefficient mu _a of the absorber α in the subject E, generates a distribution image of absorption coefficient mu _a within the object E.
The control device 500 stores the spatial position of the absorber α in the subject E calculated by the signal analysis device 400 and the distribution image of the absorption coefficient μ _a and the absorption coefficient μ _{a in} the memory 600 and also displays the object on the display 700. displaying a distribution image of absorption coefficient mu _a in the sample E.
As the memory 600, a data recording device such as an optical disk, a magnetic disk, a semiconductor memory, or a hard disk can be used.
As the display 700, a display device such as a liquid crystal display, a CRT, or an organic EL can be used.

Next, a step of acquiring a spectral characteristic image inside the tissue of the subject E with the biopsy apparatus in the present embodiment will be shown.
First, in step 1, the acoustic lens 4 of the illumination optical system 300 housed in the probe housing 900 is brought into contact with the surface of the subject E.
When a measurement start switch (not shown) is operated, the light generator 100 is driven to emit nanosecond-order pulsed light having a wavelength λ1 = 700 nm.
Next, in step 2, the illumination optical system 300 irradiates the subject E with pulsed light.
Next, in step 3, the elastic wave generated in the subject E is detected by the ultrasonic detector 200. The detected elastic wave is converted into an acoustic signal by the piezoelectric element 6.
Next, in step 4, the signal analysis device 400 calculates the position of the absorber α from the time characteristic of the acquired acoustic signal, calculates the absorption coefficient μ _a from the intensity characteristic, and absorbs the absorber α and the surrounding absorption coefficient. generating a reconstructed image of the spatial distribution of mu _a.
Next, in step 5, the control device 500 stores the calculated position information and image of the absorption coefficient μ _a of the wavelength λ 1 in the memory 600.
Next, in step 6, the control device 500 sets the wavelength of light emitted from the light generator 100 to λ2 = 850 nm.
The light generator 100 is driven to emit nanosecond-order pulsed light having a wavelength of λ2 = 850 nm.

Hereinafter, the same process as steps 2, 3 and 4, in step 7, the control unit 500 stores the position information and the image of the absorption coefficient mu _a the calculated wavelength λ2 in the memory 600.
Next, in step 8, the control unit 500 displays on the display 700 by superimposing a distribution image of absorption coefficient mu _a wavelength λ1 and .lambda.2.
Finally, in step 9, the measurement is finished.

As described above, in the biological examination apparatus according to the present embodiment, the position of the opening that irradiates the subject with the light and the position of the detection unit that detects the elastic wave are matched, and the spatial distribution of the light intensity that irradiates the subject. Is made substantially uniform.
This makes it possible to detect the photoacoustic signal with high S / N by irradiating the subject with light energy not exceeding MPE with high efficiency while minimizing the light intensity and elastic wave attenuation by the living tissue. A type of biopsy device can be provided.
In the present embodiment, a spectroscopic analysis method using the characteristics of absorption spectra of oxyhemoglobin and reduced hemoglobin is shown as an example of using a wavelength of 600 to 1500 nm. However, the present invention is not limited to this example.
For example, water, fat, protein (collagen), and the like, which are main constituents of living tissue, can be the target of spectroscopic analysis.

[Example 2]
In the second embodiment, a configuration example of a reflection type biopsy apparatus in a form different from that of the first embodiment will be described.
FIG. 12 is a schematic diagram illustrating the configuration of the biopsy apparatus in the present embodiment.
The basic configuration of the biological examination apparatus is the same as that shown in the first embodiment, and the constituent members having the same numbers have the same functions as those described in the first embodiment.
In this embodiment, a reference member 15 is newly added to the acoustic matching layer of the illumination optical system 300 as a reference for determining whether the light intensity emitted into the subject is within the maximum allowable range allowed for the subject. Provided.
The reference member 15 is embedded in the middle part of the acoustic lens 4 of the illumination optical system 300. As a material constituting the reference member 15, a colored silicon rubber, a polymer resin material, or the like can be used.
In the reference member 15, the Gruneisen parameter Γ _s determined from the absorption coefficient μ _as for light of a specific wavelength emitted by the light generator 100 and the physical properties of the material constituting the reference member 15 is known.
Consider the case where the light generator 100 emits light of wavelength λ1. The absorption coefficient of the reference member 15 with respect to the wavelength λ1 is μ _{as (} λ ₁₎ , and the light intensity irradiated to the reference member 15 is I _s . The pressure P _s of the elastic wave due to the photoacoustic effect generated in the reference member 15 is expressed by the following equation.

This equation, the pressure P _s indicates that the light intensity I _s to be irradiated on the reference member 15 is likewise increased if increased.
Here, when the maximum exposure allowance (MPE) with respect to the subject E in the pulsed light of nanosecond order of wavelength λ1 is I _MPE λ ₁ , when the reference member 15 is irradiated with light having an intensity of I _MPE λ ₁ The pressure P _sMPE of the elastic wave due to the photoacoustic effect generated in is _expressed by the following equation.

When the pressure Ps generated in the reference member 15 becomes larger than P _{sMPE, the} reference member 15 is irradiated with light having an intensity exceeding I _MPE λ ₁ .
The pressures P _s and P _{sMPE of} these elastic waves can be calculated by the calculation processing unit 12 of the signal analysis device 400 described above.
Since the attenuation of light due to propagation through the acoustic lens 4 from the reference member 15 is slight, the light intensity applied to the reference member 15 is substantially equal to the light intensity applied to the subject E.
At this time, the reference member is provided in the acoustic matching layer, and the light intensity emitted from the light generator 100 is controlled so that the light intensity of the pulsed light guided to the reference member satisfies the relationship P _s <P _sMPE. Control by means 500.
Accordingly, it is possible to control the light intensity of the pulsed light so as not to exceed the maximum allowable range allowed for the subject, and to irradiate the subject E with light having a safe intensity.
Further, it is possible to irradiate the subject E with light energy not exceeding MPE with high efficiency.
Thereby, it is possible to provide a reflective biopsy apparatus capable of detecting elastic waves with high S / N.

In the example shown in FIG. 12 of the present embodiment, the reference member 15 is embedded in the acoustic lens 4 of the acoustic matching layer, but may be provided on the surface of the acoustic lens 4 that contacts the subject E.
In this case, the elastic wave generated by the photoacoustic effect generated from the reference member 15 has a different reflectance on the acoustic lens side and the opposite side, so that the detected pressure Ps must be corrected for the influence of the reflectance.
Further, when the reference member 15 is provided in the acoustic lens 4, the reference member 15 is permanently installed, and the effective area of the measurement probe is limited. For this reason, as shown in FIG. 15, the cap member 17 in contact with the acoustic lens 4 may be provided, and the reference member 15 may be provided in the cap member.
In such a configuration, the cap member 17 may be attached only when checking the light intensity.
Further, at this time, if the cap member 17, the reference member 15 and the acoustic matching layer are made of the same material, the acoustic impedance of the interface of each member becomes equal, so that the correction of the reflectance of each detected elastic wave interface becomes unnecessary. .

Further, the reference member 15 as described in the second embodiment can be provided on the acoustic matching layer of the illumination optical system 300 described with reference to FIGS.
As described above, the living body inspection apparatus according to the second embodiment can irradiate the subject E with light having a safe intensity.
In addition, it is possible to provide a reflective biopsy apparatus capable of detecting an elastic wave with high S / N by irradiating a subject with light energy that does not exceed MPE with high efficiency.

[Example 3]
In the third embodiment, a configuration example of a reflection-type biopsy apparatus in a form different from the first and second embodiments will be described.
FIG. 13 is a schematic diagram illustrating the configuration of the biopsy apparatus in the present embodiment.
The basic configuration of the biological examination apparatus is the same as that shown in the first embodiment, and the constituent members having the same numbers have the same functions as those described in the first embodiment.
In this embodiment, instead of the ultrasonic detector 200, an ultrasonic generator / detector 201 as a means having both functions of an ultrasonic generator and an ultrasonic detector is newly provided.
The ultrasonic generator / detector 201 has a function of generating an ultrasonic wave having a specific frequency Ω and focusing and guiding it to a predetermined position in the subject E, and also has the function of the ultrasonic detector 200 described in the first embodiment. Have.
The ultrasonic generator / detector 201 can acquire the internal structure of the subject E by ultrasonic echoes.
In the biological examination apparatus according to the third embodiment, the two characteristics of the light absorption characteristic based on the photoacoustic signal described in the first embodiment and the structural characteristic based on the ultrasonic echo are acquired by an integral probe.

FIG. 14 is a diagram showing a schematic configuration of a configuration example by the ultrasonic generator / detector 201 in the present embodiment.
Variable delay elements 9a to 9g and pulsar / receiver 16 are connected to each of the plurality of arranged piezoelectric elements 6a to 6g through lead wires 8a to 8g.
The pulser / receiver 16 has the function of the receiver 10 described in the first embodiment, and also functions as a device that generates a pulse voltage to be applied to the piezoelectric element 6.
The delay times given to the piezoelectric elements 6a to 6g are τa to m, respectively.
As shown in FIG. 14, when the delay time is increased as the variable delay element 9 in the center (for example, τa = τg <τb = τf <τc = τe <τd), the combined wavefront formed by each piezoelectric element 6 is focused. It becomes the wave front.
By controlling the delay time given by the variable delay element 9 in this way, the position where the ultrasonic waves are focused can be controlled.
Further, the direction in which the ultrasonic wave travels can be controlled by the same control.
That is, the case where ultrasonic waves are transmitted also has a relationship with that described in FIG.

Hereinafter, the step of acquiring the spectral characteristic image inside the tissue of the subject E with the biopsy apparatus in the present embodiment will be described.
In steps 1 to 7, measurement is performed in the same process as in the first embodiment.
In step 8, the ultrasonic wave is irradiated to the subject E by the ultrasonic generator / detector 201.
Next, in step 9,
An ultrasonic echo generated in the subject E is detected by the ultrasonic generator / detector 201. The detected ultrasonic echo is converted into an electric signal by the piezoelectric element 6.
Next, in step 10, the signal analysis device 400 calculates the position of the measurement target from the time characteristic of the electrical signal obtained by the ultrasonic echo, calculates the structural characteristic from the intensity characteristic, and reconstructs the spatial distribution of the structural characteristic. To generate an image.
Next, in Step 11, the control device 500 stores the calculated structural property position information and image in the memory 600.
Next, in step 12, the control device 500 superimposes the distribution image of the absorption coefficient μ _{a on} the wavelengths λ 1 and λ 2 and the image of the structural characteristic, and displays them on the display 700.
Finally, in step 9, the measurement is finished.

As described above, the living body inspection apparatus according to the third embodiment can detect the elastic wave with high S / N while minimizing the attenuation of the light intensity and the elastic wave due to the living tissue.
Furthermore, ultrasonic echoes can be measured using the same probe.
Further, the apparatus configuration of FIG. 13 is such that the ultrasonic generator / detector 201 is provided in the apparatus of the first embodiment, but the same effect can be obtained even if it is provided in the apparatus of the second embodiment. .

BRIEF DESCRIPTION OF THE DRAWINGS Schematic explaining the structure of the reflection type biopsy apparatus in Example 1 of this invention. Shows the absorption spectra of HbO ₂ and Hb in wavelengths 600-1000nm range at the time of describing the measurement of the subject of Example 1 of the present invention. The figure which shows the structure of the linear array probe which is an example of the ultrasonic detector which comprises the biopsy apparatus in Example 1 of this invention. FIG. 4 is a diagram for explaining electronic focusing using the linear array probe according to the first embodiment of the present invention. Schematic explaining the structure of the 2D array probe which is the other structural example of the ultrasonic detector in Example 1 of this invention. BRIEF DESCRIPTION OF THE DRAWINGS Schematic explaining the structure of the probe of the biopsy apparatus in Example 1 of this invention. The figure explaining the flat acoustic matching layer made to function as a surface light source which emits the substantially uniform light intensity which is the other structural example of the acoustic matching layer in Example 1 of this invention. The figure which shows another structural example of the illumination optical system (probe) provided with the light-diffusion means in Example 1 of this invention. The figure which shows another structural example of the illumination optical system (probe) provided with the light-diffusion means in Example 1 of this invention. The figure which shows the light intensity distribution irradiated to the subject in the measurement of the subject of Example 1 of this invention. The figure which shows the profile of the acoustic signal at the time of measuring the test object of Example 1 of this invention. Schematic explaining the structure of the reflection-type biopsy apparatus in Example 2 of this invention. Schematic explaining the structure of the reflection-type biopsy apparatus in Example 3 of this invention. The figure which shows schematic structure of the structural example by the ultrasonic generator / detector 201 in Example 3 of this invention. Schematic explaining another structure of the reflection-type biopsy apparatus in Example 2 of this invention.

Explanation of symbols

100: Light generator 200: Ultrasonic detector 201: Ultrasonic generator / detector 300: Illumination optical system 400: Signal analysis device 500: Control device 600: Memory 700: Display 800: Main body casing 900: Probe casing 1000 : Cable E: Subject α: Absorber inside living tissue

Claims (12)

A light source that generates light for irradiating the subject;
Elastic wave detection means for detecting elastic waves generated by the subject that has absorbed the irradiated light; and
An acoustic matching layer provided on one side in contact with the elastic wave detecting means and on the other side in contact with the subject,
The light is configured to be able to irradiate the subject via the acoustic matching layer,
A biological examination apparatus comprising light diffusing means for irradiating light with substantially uniform intensity regardless of the position in the acoustic matching layer.   The biopsy apparatus according to claim 1, further comprising a light guide unit that guides the light generated by the light source to the acoustic matching layer.   The biological examination apparatus according to claim 1, wherein the light diffusing unit includes a light diffusing member provided in the acoustic matching layer.   4. The biopsy device according to claim 3, wherein the light diffusing means changes the intensity of light to be irradiated by changing the distribution density or size of the light scattering member.   The biological examination apparatus according to claim 4, wherein the light scattering member is configured by light scattering particles or stippling. The member constituting the elastic wave detecting means is constituted by a member that transmits light,
The biological examination apparatus according to claim 1 or 2, wherein the light diffusing unit is configured by a lens array disposed between the light source and the elastic wave detecting unit.   The reference member according to any one of claims 1 to 6, further comprising a reference member that serves as a reference as to whether or not the intensity of light applied to the subject is within a maximum allowable range allowed for the subject. The biopsy device according to item 1.   The reference member is provided on the acoustic matching layer (inside or in contact with the subject) or a cap member in contact with the acoustic matching layer, and the light intensity of the light guided to the reference member is allowed to the subject. The biopsy apparatus according to claim 7, further comprising a control device that performs control so as not to exceed a maximum allowable range.   The biopsy device according to claim 8, wherein the reference member is made of a material having the same acoustic impedance as that of the acoustic matching layer.   The biopsy device according to claim 8, wherein the cap member is made of a material having the same acoustic impedance as the reference member and the acoustic matching layer. An ultrasonic generator,
The said elastic wave detection means can detect the echo which generate | occur | produced in the said test object with the ultrasonic wave which generate | occur | produced from this ultrasonic generator and was irradiated to the said test object. The biological examination apparatus of any one of Claims.   The biopsy apparatus according to claim 11, wherein the ultrasonic generator is also used by the elastic wave detecting means.

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