JP2016209725A - Analyte information acquisition device and method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve such a problem that, if light emission frequency is increased for shortening an acquisition time of a reception signal, SNR is reduced since an exposure amount has to be reduced.SOLUTION: An analyte information acquisition device of the present invention comprises: a probe comprising a receiver for receiving an acoustic wave and then converting the wave into an electric signal, and a first radiation part and a second radiation part for respectively radiating pulse light to different areas on an analyte surface; and a controller for controlling radiation positions of the pulse light so that the pulse light is not radiated continuously to the analyte from the respective first and second radiation parts.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a subject information acquisition apparatus and a subject information acquisition method. In particular, the present invention relates to a subject information acquisition apparatus and a subject information acquisition method for acquiring information in a subject by irradiating the subject with pulsed light and receiving an acoustic wave generated in the subject.

  As a method for specifically imaging angiogenesis caused by cancer, photoacoustic imaging such as photoacoustic tomography (hereinafter referred to as PAT) is drawing attention. PAT is a technique for illuminating a subject such as a living body with pulsed light (near infrared light or the like), receiving a photoacoustic wave emitted from the inside of the living body, and imaging it.

  Non-Patent Document 1 discloses a handheld device using photoacoustic imaging technology. A schematic diagram of a handheld photoacoustic apparatus described in Non-Patent Document 1 is shown in FIG. In FIG. 7A, the photoacoustic probe 101 is fixed so that the receiver 102 for receiving the photoacoustic wave is sandwiched between the emission ends 103 a of the bundle fiber 103. The pulsed light generated by the light source 104 enters the incident end of the bundle fiber 103 via the illumination optical system 105, and the subject (not shown) is irradiated with the pulsed light from the output end 103a of the bundle fiber 103. The receiver 102 receives a photoacoustic wave emitted from the subject and converts it into a received signal. Then, the processing device 106 of the ultrasonic apparatus 100 performs amplification and digitization of the received signal, and then performs image reconstruction. The processing device 106 outputs the generated image data to the monitor 107 and displays a photoacoustic image.

Photons Plus Ultrasound: Imaging and Sensing 2009, Proc. of SPIE vol. 7177, 2009

  In an apparatus using the photoacoustic imaging technique, it is desirable to improve the SNR (signal-to-noise ratio) of the received signal in order to improve the contrast. Therefore, it is conceivable to reduce noise by increasing the number of times of reception signal acquisition and averaging. However, simply increasing the number of times the received signal is acquired increases the acquisition time accordingly. If the acquisition time becomes long, a positional shift or the like associated with the relative movement between the subject and the photoacoustic probe may occur, and the image performance may deteriorate. For this reason, it is conceivable to increase the irradiation frequency of the pulsed light.

  However, as shown in FIG. 7 (b), the maximum permissible exposure (MPE; Maximum Permissible Exposure) for the skin is defined in Japanese Industrial Standard (JIS) C6802. According to this rule, MPE becomes maximum when the irradiation frequency is about 10 Hz or less, and if it is increased to a higher frequency, the exposure amount must be decreased in inverse proportion. FIG. 7B shows the result of calculation at an exposure time of 10 seconds or longer and a wavelength of 800 nm. Then, when the irradiation area of the pulsed light is constant, according to the initial sound pressure p = Γμaφ (Γ: Gruneisen coefficient, μa: absorption coefficient, φ: light quantity) of the photoacoustic wave, the tissue inside the subject (light absorber) ) Decreases in inverse proportion, and the initial sound pressure p of the photoacoustic wave also decreases in inverse proportion. For example, if the irradiation frequency of the pulsed light on the subject is changed from 10 Hz to 20 Hz, the irradiation density (the amount of irradiation light per unit area) must be halved, and instead of reducing the noise by averaging, the original reception The sound pressure is lowered. Since light attenuates exponentially in the subject, it is particularly difficult for light to reach the deep part of the subject. As a result, the effect of improving the SNR cannot be obtained.

  An object of the present invention is to improve the SNR by shortening the acquisition time of a received signal in view of the above problems.

  In order to solve the above-described problems, an object information acquisition apparatus according to the present invention is an object information acquisition apparatus that acquires a characteristic distribution in a subject, and includes a light source that generates pulsed light, A receiver for receiving the acoustic wave generated in the step S3 and converting it into an electrical signal, and a first irradiation unit and a second irradiation unit for irradiating the pulsed light generated by the light source to different regions of the subject surface, respectively. The pulse, so that the subject is not continuously irradiated with pulse light from a probe, a signal processing unit that acquires a characteristic distribution in the subject using the electrical signal, and the first and second irradiation units. A control unit that controls an irradiation position of light, and the signal processing unit includes an electrical signal resulting from the pulsed light emitted from the first irradiation unit and a pulse emitted from the second irradiation unit. Averaging electrical signals caused by light Is obtained by integrating and obtaining an averaged signal or a characteristic distribution in the subject using the integrated signal, or using an electric signal resulting from pulsed light emitted from the first irradiation unit Combining the acquired distribution with the distribution acquired using the electrical signal resulting from the pulsed light emitted from the second irradiation unit, and acquiring the combined distribution as a characteristic distribution in the subject It is characterized by.

Further, the subject information acquisition method of the present invention irradiates the subject with the pulsed light generated by the light source from the first irradiating unit and the second irradiating unit, and the sound generated in the subject by the irradiation of the pulsed light. An object information acquisition method for acquiring a characteristic distribution in a subject using an electric signal output from a receiver that has received a wave, wherein the signal processing acquires the characteristic distribution in the subject using the electric signal A control step for controlling the irradiation position of the pulsed light so that the subject is not irradiated with the pulsed light continuously from each of the first and second irradiation units, and in the signal processing step, The averaged signal is obtained by averaging or integrating the electrical signal resulting from the pulsed light emitted from the first irradiation unit and the electrical signal resulting from the pulsed light emitted from the second irradiation unit. Or using the integrated signal Serial to get the characteristic distribution in the subject, or,
A distribution acquired using an electrical signal resulting from the pulsed light emitted from the first irradiation unit, and a distribution obtained using an electrical signal resulting from the pulsed light emitted from the second irradiation unit, And the synthesized distribution is acquired as a characteristic distribution in the subject.

  According to the present invention, the SNR can be improved by increasing the number of times of reception signal acquisition, and the acquisition time can be further shortened.

It is a schematic diagram explaining the apparatus structure in Embodiment 1 of this invention. It is a figure explaining the switching timing of the optical path in Embodiment 1 of this invention. It is a figure explaining the switching method of the optical path in Embodiment 1 of this invention. It is a figure explaining the switching method of the optical path in Embodiment 1 of this invention. It is a figure explaining the switching timing of the optical path in Embodiment 2 of this invention. It is a schematic diagram explaining the structure of the probe in Embodiment 3 of this invention. It is a figure explaining background art.

  The present invention will be described below with reference to the drawings. In the present invention, the acoustic wave is typically an ultrasonic wave, and includes an elastic wave called a sound wave, an ultrasonic wave, a photoacoustic wave, and an optical ultrasonic wave. The subject information acquisition apparatus of the present invention receives acoustic waves generated in a subject by irradiating the subject with light (electromagnetic waves including visible light and infrared rays), and uses the subject information as image data. Includes devices that use photoacoustic effects to be acquired.

  The acquired object information includes the initial sound pressure distribution of acoustic waves generated by light irradiation, the light energy absorption density distribution derived from the initial sound pressure distribution, the absorption coefficient distribution, the concentration distribution of the substances constituting the tissue, etc. The characteristic distribution is shown. The concentration distribution of the substance is, for example, an oxygen saturation distribution or an oxidized / reduced hemoglobin concentration distribution.

  In the present invention, pulsed light emitted from a light source is propagated to one irradiation unit, and an acoustic wave from a subject is received by a receiver. In the next light emission, pulse light is irradiated from different irradiation units, and an acoustic wave is received by the receiver. Thus, in the present invention, a plurality of pulsed light irradiation units are provided, and the subject is not irradiated with pulsed light continuously from one irradiation unit. Here, in the present invention, “the subject is not continuously irradiated with pulsed light” means that the subject is irradiated with the next pulsed light when the subject is irradiated with pulsed light once from a certain irradiation unit. Means from another irradiation unit. That is, the pulse light is not irradiated twice continuously from the same irradiation part.

  With the above configuration, the object surface (skin) where the pulsed light is actually irradiated is irradiated with light at a low frequency, but within the object, the light diffuses, There is an area where light can reach. Therefore, for example, when two irradiation units are provided, even if pulsed light is alternately irradiated to different regions from the two irradiation units on the surface of the subject, for example, at a frequency of 10 Hz, A region where pulsed light is irradiated at a frequency is formed. Therefore, the noise component can be reduced by increasing the number of times of reception signal acquisition and performing an averaging process or an integration process (addition process) between the reception signals. Further, the noise component can be reduced not by processing the received signals but also by synthesizing the image data after image reconstruction.

  This will be described in detail in the following embodiments.

(Embodiment 1)
A photoacoustic apparatus that is an object information acquiring apparatus according to the first embodiment will be described with reference to FIG. The subject information acquisition apparatus of the present invention includes at least a light source 4, a photoacoustic probe 1, and a processing device 6.

  The light source 4 generates pulsed light such as near infrared rays. As the light source 4, a laser capable of obtaining a large output is preferable, but a light emitting diode or the like can be used instead of the laser. Preferably, an Nd: YAG laser, an Alexandrite laser, or a Ti: sa laser or an OPO laser using Nd: YAG laser light as excitation light is used. In addition, various lasers such as a solid-state laser, a gas laser, a dye laser, and a semiconductor laser can be used as the laser. As for the wavelength of the generated light, a specific wavelength may be selected according to a component to be measured (for example, hemoglobin) among light in the range of 500 nm to 1300 nm.

  In the present embodiment, the pulsed light generated by the light source 4 is shaped into a beam diameter by a pulse optical system 5 that is an optical member, and is incident on a bundle fiber 3 that is also an optical member. The bundle fiber 3 is connected to the photoacoustic probe 1.

  The photoacoustic probe 1 includes a receiver 2 that receives an acoustic wave emitted from a subject and converts it into a reception signal (electric signal), and an emission end 3a as an irradiation unit that irradiates the subject with pulsed light. In the present embodiment, two emission ends 3 a are provided as two irradiation units (a first irradiation unit and a second irradiation unit) symmetrically with respect to the receiver 2 so as to sandwich the receiver 2. The exit end 3a is the exit end of the bundle fiber 3, and light is propagated by the bundle fiber 3 up to the exit end 3a.

  In the present invention, as described above, the emission end 3a of the bundle fiber 3 may be used as an irradiation unit, and the subject may be directly irradiated with light from the emission end 3a. However, any optical member such as a diffusion plate may be provided. In this case, the diffusion plate is used as an irradiation unit, and the subject is irradiated with light from the diffusion plate. Further, the optical fiber such as a mirror or a lens provided in the light-shielding tube may be used instead of using the bundle fiber 3 for drawing the pulsed light from the light source 4 to the subject. In this case, when the subject is directly irradiated with light from the emission end of the light shielding cylinder, the emission end of the light shielding cylinder serves as an irradiation unit.

  In the present embodiment, the two emission ends 3 a are arranged on the side of the receiver so as to sandwich the receiver 2. Then, a substantial total amount of light emitted from the light source 4 is propagated to each output end 3a of the bundle fiber 3a. The substantial total light amount from the light source 4 described here means the total light amount excluding light consumption due to attenuation or reflection of light being propagated or branching for light amount measurement or trigger acquisition. That is, in this embodiment, in order to propagate the pulse light to the two exit ends, it is not branched by a half mirror or the like. The total amount of light is propagated only to the exit end.

  The area of the emission end 3a of the bundle fiber (irradiation area to the subject) is the emission end width in the longitudinal direction of the receiver 2 (the width in the arrangement direction of the elements when a plurality of elements are arranged one-dimensionally). And the product of the vertical emission end width. The width in the vertical direction is narrowed in accordance with the total amount of light so that the irradiation density is as high as possible below the MPE defined in Japanese Industrial Standard (JIS) C6802. By doing so, the reception signal for one irradiation of the pulsed light is increased. Then, a substantial total amount of light from the light source 4 is emitted alternately from the output end 3a of the bundle fiber with the receiver 2 interposed therebetween. The receiver 2 receives an acoustic wave for each emission and transmits a reception signal to the processing device 6.

  The processing device 6 includes a signal processing unit 6b and a control unit 6a. The signal processing unit 6b uses, as a trigger signal, an output from a photodiode (not shown) that is a photodetector that is measured by branching a part of the pulsed light, and when the trigger signal is input, the signal is received by the receiver 2. Get a signal. The trigger signal is not limited to the output from the photodiode. A method of synchronizing the light emission of the light source 4 and the input trigger to the signal processing unit 6b may be used.

  Then, the signal processing unit 6b performs amplification and digital conversion of the received signal, and then averages the acquired received signals for a plurality of times. However, averaging may be performed before amplification or before digital conversion. Further, as the averaging method, not only a simple arithmetic average but also an averaging method such as a geometric average may be used. Further, the effect of the present invention can be obtained by simply integrating (adding) the received signals for a plurality of times instead of averaging.

  Thereafter, the signal processing unit 6b performs image reconstruction using the averaged or integrated signal, and generates image information (image data). Here, the image data is a set of voxel data or pixel data, and the image data indicates a characteristic distribution such as an absorption coefficient distribution and an oxygen saturation distribution in the subject. The signal processing unit 6b outputs the image data to the monitor 7 for display.

  Further, in the present invention, not only processing such as averaging and integration of received signals but also image data may be combined after image reconstruction. That is, the image data may be combined after image reconstruction using each received signal resulting from light irradiation from each irradiation unit. The process of combining image data refers to a process of reducing noise components by adding, multiplying, and averaging pixel data (or voxel data) of each image data. Specifically, using image data (first distribution) acquired using a reception signal resulting from light irradiation from the first irradiation unit and a reception signal resulting from light irradiation from the second irradiation unit. Are combined (for example, averaged) with the acquired image data (second distribution). Then, synthesized (for example, averaged) image data (for example, averaged distribution) is set as a characteristic distribution in the subject. Here, the synthesis processing between the image data may be synthesis of luminance data subjected to various image processing such as edge enhancement and contrast adjustment, or may be synthesis of data before being converted into luminance data.

  The control unit 6a controls the light irradiation position so that the subject is not irradiated with light continuously from one irradiation unit. In the present embodiment, the control unit 6a controls the irradiation position of the pulsed light by controlling the switching device 8.

  The switching device 8 switches the optical path of the pulsed light from the light source 4 in order to change the irradiation position of the pulsed light. In FIG. 1, a switching device 8 is provided between the light source 4 and the pulse optical system 5 that shapes the beam diameter from the light source 4. The switching device 8 switches the incidence on the pulse optical system 5 based on switching information that is a control signal from the control unit 6 a in the processing device 6. By this switching, pulsed light is alternately emitted from the emission end 3a provided so as to sandwich the receiver 2.

(Pulse light irradiation control)
Next, the control method of the control part 6a is demonstrated using the timing chart of FIG.2 (b). FIG. 2A is a schematic view of the photoacoustic probe 1 as viewed from the side, and the two emission ends 3a are provided symmetrically so as to sandwich the receiver 2, so that the irradiation positions are the A side and the B side. It is divided into.

  In the timing chart of FIG. 2B, the light emission frequency of the light source 4 is set to 20 Hz as an example. Therefore, the light source 4 emits light every 50 msec. First, the switching device 8 emits pulsed light to the irradiation position on the A side, and the signal processing unit 6b receives the acoustic wave generated by the light irradiation from the A side using the receiver 2 and acquires the received signal. The switching device 8 switches so that the pulsed light is irradiated to the irradiation position on the B side between the irradiation from the A side and the next light emission. The receiver 2 receives an acoustic wave generated by light irradiation from the B side and acquires a reception signal.

  Since the pulsed light is irradiated symmetrically around the receiver 2, the irradiated pulsed light diffuses at a predetermined depth in the subject (for example, the depth of the subject is 3 mm or more). In other words, light reaches the region in a predetermined angle range with the center line directly below the receiver 2 from irradiation on either the A side or the B side. It is also generated by irradiation. The reception signal resulting from the light irradiation from the A side and the reception signal resulting from the light irradiation from the B side have substantially the same signal waveform.

  Therefore, since the frequency at which the acoustic wave is generated can be increased twice (20 Hz) inside the subject, the signal that can be acquired within the same time can be doubled compared to when receiving at 10 Hz. Therefore, the noise component can be reduced by averaging or integrating the acquired reception signals. Compared with the averaging effect at 10 Hz, the averaging effect obtained at 20 Hz within the same time can reduce the noise by about 1 / √2. Of course, the effect of the present invention can also be obtained by combining the image data.

Further, even if the frequency of pulsed light irradiation on the subject is increased to 20 Hz, the irradiation area on the surface of the subject changes with each irradiation (the same area is not irradiated continuously), so the irradiation frequency on the same irradiation area Remains one time (10 Hz). That is, even if the light emission frequency of the light source 4 is 20 Hz with the substantial total amount of light from the light source 4, the same area on the subject surface is irradiated with pulsed light at 10 Hz, so the upper limit of MPE for the skin is 30 mJ. Irradiation can be performed with an irradiation density of about / cm ² . Therefore, the photoacoustic generated from the subject and its received signal can be acquired with the intensity when the light source 4 emits light at 10 Hz.

  As described above, since the number of acquisitions can be increased without reducing the strength of the received signals, the noise component can be reduced by the effect of averaging of the received signals, integration processing, or synthesis processing of the image data. Although the light emission frequency of the light source 4 has been described as 20 Hz, this shows an example in which the light emission frequency can be doubled without reducing the substantial total amount of light from the light source 4, and the present invention is not limited to this. Not.

(Specific configuration of switching device)
Next, the switching device 8 will be described with reference to FIGS. 3 and 4. In order to simplify the description of the switching device 8, the pulse optical system 5 is not shown in FIGS.

  The switching device 8 in FIG. 3A includes a mirror 8b that switches an optical path between the A side and the B side (the first irradiation unit side and the second irradiation unit side), an actuator 8a that drives the mirror 8b, Consists of. In order to make the pulse light incident on the incident end 3b of the bundle fiber on the A side, the mirror 8b is driven so as to reflect the light (see the upper diagram in FIG. 3A). Further, in order to make the pulse light incident on the incident end 3b of the bundle fiber on the B side, the mirror 8b is driven so as not to hit the light (see the lower diagram in FIG. 3A). In any drive, the actuator 8a is driven by a control signal from the controller 6a. The switching by the combination of the actuator 8a and the mirror 8b may be configured to switch between the A side and the B side by changing the position of the mirror 8b on the actuator 8a as shown in FIG.

  Further, the switching device 8 in FIG. 4A uses a polygon mirror 8c instead of the actuator 8a and the mirror 8b. The polygon mirror 8c rotates in synchronization with the light emission frequency of the light source 4 and is adjusted so as to be incident on each incident end 3b of the bundle fiber on the A side and the B side.

  The switching device 8 is not limited to the configuration described with reference to FIGS. 3A, 3B, and 4C, and a galvano mirror, an acousto-optic deflection element (AOD), or the like is applicable.

  Furthermore, in the present invention, the irradiation position can be switched without using the switching device 8. Specifically, as shown in FIG. 4B, a light source 4 composed of a first light source and a second light source is used. And the light source 4 can switch an irradiation position by controlling the light emission timing of a 1st light source and a 2nd light source based on the control signal from the control part 6a.

  As described above, in this embodiment, since the number of acquisitions can be increased without reducing the strength of the received signals, the noise component is reduced by the effect of averaging of the received signals, integration processing, or synthesis processing of the image data. be able to. As a result, since the SNR is improved, the contrast is improved when imaged, and the visibility and clinical diagnostic ability are improved.

(Embodiment 2)
Embodiment 1 demonstrated the form which provided the exit end 3a of the bundle fiber used as the irradiation area | region of a pulsed light so that the receiver 2 may be pinched | interposed one by one, and may irradiate alternately. In the second embodiment, a description will be given of a mode in which a larger number of emission ends that are irradiation units are provided. Since the configuration other than the number of optical paths of the pulsed light from the light source and the configuration of the photoacoustic probe is the same as that of the first embodiment, the description thereof is omitted.

  Fig.5 (a) is the schematic diagram which looked at the photoacoustic probe 1 of this embodiment from the side surface direction. The photoacoustic probe 1 is provided with four emission ends 3a (a first irradiation unit, a second irradiation unit, a third irradiation unit, and a fourth irradiation unit). The position is divided into two locations, A side B side and C side D side. A substantial total amount of light from the light source 4 is emitted from the emission end 3a of the bundle fiber. In the timing chart of FIG. 5B, the light emission frequency of the light source 4 is set to 40 Hz as an example. That is, the light source 4 emits light every 25 msec.

  In FIG. 5B, first, pulse light is incident on the A side by the switching device 8, and a reception signal of acoustic waves resulting from light irradiation from the A side is acquired by the receiver 2. Between this pulse light irradiation and the next pulse light emission, the switching device 8 switches so that the pulse light is incident on the B side. And the receiver 2 acquires the received signal of the acoustic wave resulting from the light irradiation from the B side. Such a flow is repeated on the C side and the D side. In addition, although the light emission frequency of the light source 4 was demonstrated as 40 Hz, it is not limited to this.

  Here, the irradiation positions on the outer A side and D side are symmetrical with respect to the receiver 2, and the irradiation positions on the inner B side and C side are also symmetrical with respect to the receiver 2. Therefore, when the depth of the subject is equal to or greater than a predetermined depth (particularly, the depth of the subject is 3 mm or more), the irradiated light is diffused, resulting in pulsed light irradiated from the outside (A side and D side). The reception signals to be transmitted have substantially the same signal waveform. Similarly, the reception signals resulting from the pulsed light irradiated from the inside (B side and C side) also have substantially the same signal waveform.

  However, since the inner irradiation position and the outer irradiation position are not symmetrical with respect to the receiver 2, the reception signal caused by the irradiation from the inner side and the reception signal caused by the irradiation from the outer side are signal waveforms. The difference comes out. For example, at a position in the subject under the receiver, the amount of light reaching the irradiation from the outside is lower than the irradiation from the inside. Due to the difference in the amount of light, the sound pressure of the received acoustic wave also varies, so the signal waveform of the received signal also varies. That is, the reception signal resulting from irradiation from the outside has a smaller amplitude (intensity) than the reception signal resulting from irradiation from the inside.

  Therefore, it is preferable that the signal processing unit 6b corrects the received signal by irradiation from the outside and irradiation from the inside. Specifically, the amplitude may be adjusted by multiplying the received signal resulting from irradiation from the inside by the gain of the decrease. By doing so, the received signal is substantially the same regardless of the irradiation position from any irradiation position from the A side to the D side.

  The gain depends on the depth of the subject, and may be analytically determined according to the distance from the receiver 2 at each irradiation position from the outside and inside and the subject tissue. The light diffusion equation and the initial sound pressure p = Γμaφ (Γ: Gruneisen coefficient, μa: absorption coefficient, φ: light quantity) can be used for the analysis. Alternatively, the gain may be experimentally determined using a phantom with known optical characteristics.

  In the present embodiment, the order of irradiation with pulsed light is not limited to the order shown in FIG. 5B, and it is sufficient that at least the same irradiation position is not continuously irradiated. Further, in FIG. 5A, the bundle fiber exit ends 3a, which are the irradiation positions, are provided at two locations across the receiver 2, but the number may be further increased. For switching of the irradiation position of the pulsed light, the switching device 8 and the switching method described in the first embodiment with reference to FIGS. 3 and 4 may be applied.

  As described above, according to the second embodiment, since the number of acquisitions can be further increased (that is, the irradiation frequency is further increased) without significantly reducing the intensity of the reception signals, the reception signals are averaged, integrated, or imaged. The noise component can be reduced by the effect of the data synthesizing process. As a result, since the SNR is improved, the contrast is improved when imaged, and the visibility and clinical diagnostic ability are improved.

(Embodiment 3)
In the first and second embodiments, a description has been given of a mode in which the bundle fiber emitting end 3a, which is a pulsed light irradiation unit, is provided symmetrically with the receiver 2 interposed therebetween. The third embodiment will be described with respect to a configuration in which a plurality of bundle fiber emitting ends 3 a are provided on one side surface of the receiver 2. As an example, in FIG. 6, the two exit ends 3 a of the bundle fiber are both provided on one side of the receiver 2. Note that the basic apparatus configuration, averaging of received signals, integration processing, or image data synthesizing methods have been described in the first and second embodiments, and thus description thereof is omitted here.

  In FIG. 6, as described in the second embodiment, since the distance from the receiver 2 is different between the pulsed light irradiation area A side and the B side, the intensity of the acoustic wave received by the receiver 2 is different. Therefore, it is preferable to multiply the received signal by a gain determined analytically and / or experimentally.

  Further, in combination with the second embodiment, different numbers may be provided, such as two emission ends 3a of the bundle fiber that is a pulse light irradiation unit on one side and three on the other side.

  As described above, according to the third embodiment, the position of the emission end of the pulsed light provided adjacent to the receiver 2 can be arbitrarily provided. Therefore, it becomes easy to make the photoacoustic probe 1 into a shape that the operator can easily grasp.

DESCRIPTION OF SYMBOLS 1 Photoacoustic probe 2 Receiver 3 Bundle fiber 3a Outgoing end 3b Incoming end 4 Light source 5 Pulse optical system 6 Processing apparatus 6a Control part 6b Signal processing part 7 Monitor 8 Switching apparatus

Claims (10)

An object information acquisition apparatus for acquiring a characteristic distribution in an object,
A light source that generates pulsed light;
A receiver for receiving an acoustic wave generated in the subject by the pulsed light and converting it into an electrical signal; a first irradiating unit for irradiating the different regions of the subject surface with the pulsed light generated by the light source; A probe having a second irradiation section;
A signal processing unit for obtaining a characteristic distribution in the subject using the electrical signal;
A control unit that controls the irradiation position of the pulsed light so that the subject is not irradiated with pulsed light continuously from each of the first and second irradiation units;
Have
The signal processing unit
The electric signal resulting from the pulsed light emitted from the first irradiation unit and the electric signal resulting from the pulsed light emitted from the second irradiation unit are averaged or integrated, and the averaged signal or Using the integrated signal to obtain a characteristic distribution in the subject, or
A distribution acquired using an electrical signal resulting from the pulsed light emitted from the first irradiation unit, and a distribution obtained using an electrical signal resulting from the pulsed light emitted from the second irradiation unit, A subject information acquisition apparatus characterized in that the combined distribution is acquired as a characteristic distribution in the subject.   The object information acquiring apparatus according to claim 1, wherein the first and second irradiation units are arranged on a side surface of the receiver.   The object information acquiring apparatus according to claim 1, wherein the first and second irradiation units are arranged symmetrically with respect to the receiver.   4. The control unit according to claim 1, wherein the control unit controls the pulsed light to be alternately emitted from the first irradiation unit and the second irradiation unit. 5. Subject information acquisition apparatus. A switching device that switches an optical path of pulsed light from the light source between the first irradiation unit side and the second irradiation unit side;
The subject information acquisition apparatus according to claim 1, wherein the control unit controls the irradiation position by controlling the switching device. The light source comprises a first light source that generates pulsed light propagated to the first irradiation unit, and a second light source that generates pulsed light propagated to the second irradiation unit,
5. The subject information acquisition apparatus according to claim 1, wherein the control unit controls the irradiation position by controlling light emission timings of the first and second light sources. 6. .   The object according to claim 1, wherein the probe further includes an irradiation unit other than the first and second irradiation units for irradiating the subject with the pulsed light. Sample information acquisition device.   The object information according to claim 7, wherein the signal processing unit corrects the intensity of each electric signal caused by the pulsed light emitted from each irradiation unit according to the position of each irradiation unit. Acquisition device.   The subject information acquiring apparatus according to claim 1, wherein both the first and second irradiation units are arranged on one side of the receiver. An electrical signal output from a receiver that irradiates a subject with pulsed light generated by a light source from the first and second irradiating units and receives an acoustic wave generated in the subject by irradiation with the pulsed light. An object information acquisition method for acquiring a characteristic distribution in an object using
A signal processing step of obtaining a characteristic distribution in the subject using the electrical signal;
A control step of controlling the irradiation position of the pulsed light so that the subject is not irradiated with pulsed light continuously from each of the first and second irradiation units;
Have
In the signal processing step,
The electric signal resulting from the pulsed light emitted from the first irradiation unit and the electric signal resulting from the pulsed light emitted from the second irradiation unit are averaged or integrated, and the averaged signal or Using the integrated signal to obtain a characteristic distribution in the subject, or
A distribution acquired using an electrical signal resulting from the pulsed light emitted from the first irradiation unit, and a distribution obtained using an electrical signal resulting from the pulsed light emitted from the second irradiation unit, And acquiring the synthesized distribution as a characteristic distribution in the subject.