JP2019072647A - Analyte information acquisition device and method - Google Patents

Abstract

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 an object information acquiring apparatus and an object information acquiring method. In particular, the present invention relates to an object information acquiring apparatus and an object information acquiring method for irradiating pulsed light to an object, receiving an acoustic wave generated in the object, and acquiring information in the object.

  Photoacoustic imaging such as photoacoustic tomography (hereinafter referred to as PAT (Photoacoustic tomography)) has attracted attention as a method of specifically imaging angiogenesis generated due to cancer. The PAT is a technology for illuminating pulsed light (near infrared rays etc.) on a subject such as a living body and receiving and imaging a photoacoustic wave emitted from the inside of the living body.

  Non-Patent Document 1 discloses a handheld device using photoacoustic imaging technology. A schematic view of the hand-held photoacoustic apparatus described in Non-Patent Document 1 is shown in FIG. 7 (a). In FIG. 7A, the photoacoustic probe 101 fixes a receiver 102 for receiving the photoacoustic wave so as to be sandwiched by the output end 103 a of the bundle fiber 103. The pulsed light generated by the light source 104 is incident on the incident end of the bundle fiber 103 through the illumination optical system 105, and the pulsed light is emitted from the emission end 103a of the bundle fiber 103 to an object (not shown). The receiver 102 receives the photoacoustic wave emitted from the inside of the subject and converts it into a received signal. Then, the processing unit 106 of the ultrasonic apparatus 100 amplifies and digitizes the received signal, and then performs image reconstruction. The processing device 106 outputs the generated image data to the monitor 107 to display the photoacoustic image.

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

  In an apparatus using photoacoustic imaging technology, it is desirable to improve the signal-to-noise ratio (SNR) of the received signal in order to improve the contrast. Therefore, it is conceivable to reduce noise by increasing the number of times of acquisition of received signals and averaging them. However, simply increasing the number of times of acquisition of the reception signal extends the acquisition time accordingly. When the acquisition time becomes long, positional deviation or the like may occur due to relative movement between the subject and the photoacoustic probe, which may degrade the performance of the image. Therefore, it is conceivable to increase the irradiation frequency of pulsed light.

  However, as shown in FIG. 7 (b), Maximum Permissible Exposure (MPE) to the skin is defined by Japanese Industrial Standard (JIS) C6802. According to this definition, the MPE is maximized when the irradiation frequency is about 10 Hz or less, and if it is increased to a higher frequency, the exposure dose must be reduced in inverse proportion. FIG. 7B is the result of calculation at a wavelength of 800 nm and an exposure time of 10 seconds or more. Then, when the irradiation area of the pulse light is constant, the tissue inside the subject (a light absorber according to the initial sound pressure of the photoacoustic wave p = Γμaφ (Γ: Gruneisen coefficient, μa: absorption coefficient, φ: light quantity) The light amount φ to) decreases in inverse proportion, and the initial sound pressure p of the photoacoustic wave also decreases in inverse proportion. For example, when the irradiation frequency of pulsed light to an object is 10 Hz to 20 Hz, the irradiation density (irradiated light amount per unit area) must be halved, and instead of averaging to reduce noise, the original reception I will lower the sound pressure. In the subject, the light attenuates exponentially, so that it is particularly difficult for the light to reach the deep part of the subject. As a result, the effect of SNR improvement can not be obtained.

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

  In order to solve the above problems, an object information acquiring apparatus according to the present invention is an object information acquiring apparatus for acquiring a characteristic distribution in an object, the light source generating pulse light, and the inside of the object using the pulse light. A receiver for receiving an acoustic wave generated by the light source and converting it into an electrical signal, and a first irradiation unit and a second irradiation unit for irradiating the pulse light generated by the light source to different areas of the object surface The pulse that the pulse light is not continuously irradiated to the subject from each of the probe, the signal processing unit for acquiring the characteristic distribution in the subject using the electric signal, and the first and second irradiation units And a controller configured to control an irradiation position of the light, wherein the signal processing unit includes an electric signal caused by the pulsed light irradiated from the first irradiation unit and a pulse irradiated from the second irradiation unit. Averaging electrical signals caused by light Integrating and acquiring the characteristic distribution in the object using the averaged signal or the integrated signal, or using an electrical signal resulting from the pulsed light emitted from the first irradiation unit Combining the acquired distribution and a distribution acquired using an electrical signal derived from the pulsed light emitted from the second irradiation unit, and acquiring the combined distribution as the characteristic distribution in the object It is characterized by

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

  According to the present invention, it is possible to improve the SNR by increasing the number of times of acquisition of the reception signal, and further to shorten the acquisition time.

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.

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

  The acquired object information includes the initial sound pressure distribution of the acoustic wave 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 material constituting the tissue, etc. The characteristic distribution of The concentration distribution of the substance is, for example, an oxygen saturation distribution or an oxygenated / reduced hemoglobin concentration distribution.

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

  According to the above configuration, the position of the object surface (skin) to which pulse light is actually irradiated is irradiated with light at a low frequency, but the light is diffused inside the object so that either irradiation unit There is an area where light also reaches. Therefore, for example, when two irradiation units are provided, even if pulse light is irradiated alternately at a frequency of 10 Hz to regions different from the two irradiation units on the surface of the object, for example, 20 Hz There is an area where pulsed light is emitted at the frequency. Therefore, noise components can be reduced by averaging the number of times of acquisition of reception signals and performing averaging processing or integration processing (addition processing) of the reception signals. The noise component can also be reduced not by processing received signals but by combining image data after image reconstruction.

  This will be described in more detail in the following embodiments.

(Embodiment 1)
A photoacoustic apparatus which is the object information acquiring apparatus of Embodiment 1 will be described with reference to FIG. The subject information acquisition apparatus of the present invention comprises 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 light. Although a laser capable of obtaining a large output is preferable as the light source 4, it is also possible to use a light emitting diode or the like instead of the laser. Preferably, an Nd: YAG laser or an alexandrite laser, or a Ti: sa laser or an OPO laser using Nd: YAG laser light as excitation light is used. Besides, as the laser, various lasers such as a solid state laser, a gas laser, a dye laser and a semiconductor laser can be used. It is preferable to select a specific wavelength of the generated light according to the component (for example, hemoglobin) to be measured among the light in the range of 500 nm to 1300 nm.

  In the present embodiment, the pulse light generated by the light source 4 is shaped into a beam diameter by the pulse optical system 5 which is an optical member, and is incident on the bundle fiber 3 which 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 received signal (electrical signal), and an emission end 3a as an irradiation unit that irradiates the subject with pulsed light. In the present embodiment, two emission ends 3a 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 emitting end 3 a is an emitting end of the bundle fiber 3, and light is propagated by the bundle fiber 3 up to the emitting end 3 a.

  In the present invention, as described above, the output end 3a of the bundle fiber 3 may be used as an irradiation unit, and light may be directly irradiated from the output end 3a to the object. However, any optical member such as a diffusion plate may be provided. In this case, the diffusion plate is an irradiation unit, and light is irradiated from the diffusion plate to the subject. In addition, the optical fiber 4 may not be used for drawing the pulsed light from the light source 4 to the subject but an optical member such as a mirror or a lens provided in the light shielding cylinder may be used. In this case, when light is directly irradiated to the object from the light emission end of the light shielding cylinder, the light emission end of the light shielding cylinder is the irradiation unit.

  In the present embodiment, the two emission ends 3 a are disposed on the side of the receiver so as to sandwich the receiver 2. Then, the substantially total amount of light emitted from the light source 4 is propagated to the respective emission ends 3a of the bundle fibers 3a. Here, the substantial total light amount from the light source 4 described herein means the total light amount excluding light attenuation and reflection during propagation, or light consumption due to light amount measurement and branching for acquiring a trigger. That is, in the present embodiment, in order to propagate pulse light to two emission ends, the light is not split by a half mirror or the like, and one acoustic wave is received from one light source 4 at the time of acoustic wave reception once (that is, The total light intensity is transmitted only to the emitting end.

  The area of the emission end 3a of the bundle fiber (the irradiation area to the object) is the width of the emission end in the longitudinal direction of the receiver 2 (the width in the array direction of the elements when a plurality of elements are arrayed in one dimension) And the output end width in the vertical direction. The width in the vertical direction is narrowed in accordance with the substantial total light amount so as to obtain an irradiation density as high as possible, which is equal to or less than the MPE defined in Japanese Industrial Standard (JIS) C6802. By doing this, the received signal per irradiation of pulsed light becomes large. Then, a substantial total amount of light from the light source 4 is emitted alternately from the emitting end 3 a of the bundle fiber sandwiching the receiver 2. The receiver 2 receives an acoustic wave for each emission and transmits a received signal to the processing device 6.

  The processing device 6 includes a signal processing unit 6 b and a control unit 6 a. The signal processing unit 6b uses an output from a photodiode (not shown), which is a light detector that measures a part of the pulsed light, as a trigger signal as a trigger signal, and when the trigger signal is input, it 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, after performing amplification and digital conversion of the received signal, the signal processing unit 6b averages the acquired received signals for a plurality of times. However, averaging may be performed before amplification or before digital conversion. Further, the averaging method may use not only a simple arithmetic mean but also an averaging method such as a geometric mean. Furthermore, the effects of the present invention can be obtained even if integration processing (addition processing) is performed on 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 this image data indicates a characteristic distribution such as an absorption coefficient distribution or an oxygen saturation distribution in a subject. The signal processing unit 6 b outputs the image data to the monitor 7 for display.

  Further, in the present invention, not only the processing such as averaging or integration of the received signals, but also the image data may be combined after the image reconstruction. That is, the image data may be combined after image reconstruction is performed using the respective reception signals resulting from the light irradiation from the irradiation units. The process of combining image data indicates a process of reducing noise components by adding, multiplying, and averaging pixel data of each image data (or voxel data). Specifically, image data (first distribution) acquired using a reception signal caused by light irradiation from the first irradiation unit and a reception signal caused by light irradiation from the second irradiation unit are used. Image data (second distribution) obtained by the above-described image synthesis (for example, averaging). Then, the synthesized (eg, averaged) image data (eg, averaged distribution) is taken as the characteristic distribution in the subject. Here, the combining process of the image data may be combining of brightness data subjected to various image processes such as edge enhancement and contrast adjustment, or combining of data before being converted into brightness data.

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

  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, the switching device 8 is provided between the light source 4 and the pulse optical system 5 for shaping 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 which is a control signal from the control unit 6 a in the processing device 6. By this switching, pulsed light is emitted alternately from the emission ends 3a provided so as to sandwich the receiver 2.

(Illumination control of pulsed light)
Next, a control method of the control unit 6a will be described using a timing chart of FIG. 2 (b). FIG. 2A is a schematic view of the photoacoustic probe 1 viewed from the side direction, and two emission ends 3a are symmetrically provided so as to sandwich the receiver 2, so that the irradiation positions are A side and B side. Divided into

  In the timing chart of FIG. 2B, the light emission frequency of the light source 4 is 20 Hz as an example. Therefore, the light source 4 emits light every 50 msec. First, pulse light is irradiated to the irradiation position on the A side by the switching device 8, and the signal processing unit 6b receives an acoustic wave generated by light irradiation from the A side using the receiver 2, and acquires a reception signal. The switching device 8 switches so that the irradiation position on the B side is irradiated with the pulse light 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 about the receiver 2, the irradiated pulsed light is diffused when the predetermined depth in the subject (for example, the depth of the subject is 3 mm or more). That is, since light reaches from the irradiation on either the A side or the B side to the region of the predetermined angle range with the center line directly below the receiver 2, the acoustic wave is also on the A side or the B side at that position. It also occurs due to the irradiation of The received signal resulting from the light irradiation from the A side and the received 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 doubled (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, noise components can be reduced by averaging or integrating the acquired received signals. The averaging effect at 20 Hz acquired within the same time can reduce noise approximately by 1 / √2 as compared to the averaging effect at 10 Hz. Of course, the effects of the present invention can be obtained by combining the image data.

In addition, even if the frequency of the pulse light irradiation to the subject is increased to 20 Hz, the irradiation area to the object surface changes with each irradiation (the same area is not continuously irradiated), so the irradiation frequency to the same irradiation area Remains at 1x (10 Hz). That is, even if the light emission frequency of the light source 4 is 20 Hz with substantially total light quantity from the light source 4, the same area on the surface of the object is irradiated with pulse light at 10 Hz. Irradiation can be performed with an irradiation density of about / cm ² . Therefore, the photoacoustic generated from the subject and the reception signal thereof can be acquired at the intensity when the light source 4 emits light at 10 Hz.

  As described above, since the number of times of acquisition can be increased without decreasing the strength of the received signal, noise components can be reduced by the effects of averaging and integration of the received signals or combining of the image data. In addition, although the light emission frequency of the light source 4 was demonstrated as 20 Hz, this shows an example which can double the light emission frequency, without reducing the substantial total light quantity from the light source 4, and this invention limits it to this I will not.

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

  The switching device 8 in FIG. 3A includes a mirror 8b that switches the optical path between the A side and the B side (the first irradiation unit side and the second irradiation unit side), and an actuator 8a that drives the mirror 8b. It consists of In order to make pulsed light enter the incident end 3b of the bundle fiber on the A side, the mirror 8b is driven to reflect the light (see the upper figure in FIG. 3A). In addition, in order to make pulse light enter 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 figure in FIG. 3A). In either drive, the actuator 8a is driven by a control signal from the control unit 6a. Further, the switching based on 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. 3B.

Furthermore, the switching device 8 of FIG. 4A applies 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 to be incident on the respective incident ends 3b of the bundle fibers on the A side and the B side.

  In addition to the configurations described in FIGS. 3A, 3B, 3C, and 4A, the switching device 8 may be a galvano mirror, an acousto-optic deflector (AOD), or the like.

  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 including 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 the present embodiment, since the number of acquisitions can be increased without decreasing the strength of the received signal, noise components are reduced by the effects of averaging and integration of the received signals or combining of the image data. be able to. As a result, since the SNR is improved, imaging improves the contrast and improves the visibility and the clinical diagnostic ability.

Second Embodiment
Embodiment 1 demonstrated the form which provides the radiation | emission end 3a of the bundle fiber used as the irradiation area | region of pulsed light so that the receiver 2 may be pinched | interposed one place each, and it irradiates alternately. In the second embodiment, a mode in which the number of emission ends that are the irradiation units is increased will be described. The configuration other than the number of optical paths of pulsed light from the light source and the configuration of the photoacoustic probe is the same as that of the first embodiment, and thus the description will be omitted.

  Fig.5 (a) is the schematic diagram which looked at the photoacoustic probe 1 of this embodiment from the side direction. The photoacoustic probe 1 is provided with four emission ends 3a (a first irradiation unit, a second irradiation unit, a third irradiation unit, a fourth irradiation unit), and irradiation is performed with the receiver 2 interposed therebetween. The position is divided into two at each of the A side B side and the C side D side. Substantially the 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 40 Hz as an example. That is, the light source 4 emits light every 25 msec.

  In FIG. 5B, first, pulse light is made incident on the A side by the switching device 8, and the receiver 2 acquires a reception signal of an acoustic wave caused by light irradiation from the A side. After the pulsed light irradiation and before the next pulsed light emission, the switching device 8 switches so that the pulsed 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 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 A side and the D side on the outer side are symmetrical with respect to the receiver 2, and the irradiation positions on the B side and the C side with the inner side are also symmetrical with respect to the receiver 2. Therefore, since the irradiated light is diffused when the depth of the object is a predetermined depth or more (in particular, the depth of the object is 3 mm or more), the pulse light emitted from the outside (A side and D side) is caused The received signals have substantially the same signal waveform. Similarly, the reception signals resulting from the pulsed light emitted from the inner side (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 received signal caused by the irradiation from the inner side and the received signal caused by the irradiation from the outer side have signal waveforms Makes a difference. For example, at a position in the subject below the receiver, the illumination from the outside has a lower amount of light reaching than the illumination from the inside. Due to the difference in the amount of light, the sound pressure of the received acoustic wave also changes, so the signal waveform of the received signal also changes. That is, the reception signal resulting from the irradiation from the outside has smaller amplitude (intensity) than the reception signal resulting from the irradiation from the inside.

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

  The gain depends on the depth of the subject, and may be analytically determined in accordance with the distance from the receiver 2 to each of the irradiation positions from the outside and the inside and the tissue of the subject. For the analysis, it is possible to use a light diffusion equation and an initial sound pressure of acoustic wave p = Γμaφ (Γ: Gruneisen coefficient, μa: absorption coefficient, φ: light quantity). Alternatively, the gain may be determined experimentally using a phantom whose optical characteristics are known.

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

  As described above, according to the second embodiment, the number of acquisitions can be further increased (that is, the irradiation frequency can be further increased) without reducing the strength of the received signal so much. The noise component can be reduced by the effect of the synthesis processing of data. As a result, since the SNR is improved, imaging improves the contrast and improves the visibility and the clinical diagnostic ability.

(Embodiment 3)
Embodiment 1 and Embodiment 2 demonstrated the form which provided the output end 3a of the bundle fiber which is an irradiation part of pulsed light symmetrically so that the receiver 2 might be pinched | interposed. Embodiment 3 demonstrates the form which provided the radiation | emission end 3a of the several bundle fiber in the one side surface side of the receiver 2. FIG. As an example, in FIG. 6, both of the two output ends 3 a of the bundle fiber are provided on one side of the receiver 2. The basic apparatus configuration, the averaging and integration processing of received signals, and the method of combining image data are described in the first and second embodiments, and thus the 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 irradiation region A side and the side B of the pulsed light, the intensity of the acoustic wave received by the receiver 2 is different. Therefore, the received signal may be multiplied by an analytically and / or experimentally determined gain.

  Further, in combination with the second embodiment, different numbers may be provided, such as two points on one side and three points on the other side of the output end 3a of the bundle fiber which is the irradiation part of pulse light.

  As described above, according to the third embodiment, the position of the emission end of 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 is easy for the operator to hold.

REFERENCE SIGNS LIST 1 photoacoustic probe 2 receiver 3 bundle fiber 3 a emission end 3 b incident end 4 light source 5 pulse optical system 6 processing device 6 a control unit 6 b signal processing unit 7 monitor 8 switching device

Claims (10)

A subject information acquisition apparatus for acquiring a characteristic distribution in a subject, comprising:
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 pulsed light generated by the light source to different areas of the subject surface; A probe having a second irradiation unit;
A signal processing unit that acquires a characteristic distribution in a subject using the electrical signal;
A control unit that controls an irradiation position of the pulse light so that the pulse light is not continuously irradiated to the subject from each of the first and second irradiation units;
Have
The signal processing unit
An averaged signal or an averaged signal obtained by averaging or integrating an electrical signal caused by the pulsed light emitted from the first irradiation unit and an electrical signal caused by the pulsed light emitted from the second irradiation unit Acquiring the characteristic distribution in the object using the integrated signal, or
A distribution obtained using an electrical signal originating from the pulsed light emitted from the first irradiating unit, and a distribution obtained using an electrical signal originating from the pulsed light emitted from the second irradiating unit, An object information acquiring apparatus characterized in that it synthesizes and acquires the synthesized distribution as a characteristic distribution in the object.   The object information acquiring apparatus according to claim 1, wherein the first and second irradiation units are disposed 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.   The said control part is controlled so that the said pulsed light may be radiate | emitted alternately from the said 1st irradiation part and the said 2nd irradiation part, It is characterized by the above-mentioned. Subject information acquisition device. It has a switching device for switching an optical path of pulse light from the light source between the first irradiation unit side and the second irradiation unit side.
The subject information acquiring apparatus according to any one of claims 1 to 4, wherein the control unit controls the irradiation position by controlling the switching device. The light source includes a first light source generating pulse light propagated to the first irradiation unit, and a second light source generating pulse light propagated to the second irradiation unit.
The object information acquiring apparatus according to any one of claims 1 to 4, wherein the control means controls the irradiation position by controlling light emission timings of the first and second light sources. .   The subject according to any one of claims 1 to 6, wherein the probe further includes an irradiation unit other than the first and second irradiation units for irradiating the object with the pulse light. Sample information acquisition device.   The object information according to claim 7, wherein the signal processing unit corrects the intensity of each electrical signal caused by the pulsed light emitted from each of the irradiation units according to the position of each of the irradiation units. Acquisition device.   The object information acquiring apparatus according to claim 1, wherein the first and second irradiation units are both disposed on one side of the receiver. An electrical signal output from a receiver that emits pulsed light generated by a light source to a subject from the first irradiation unit and the second irradiation unit, and receives an acoustic wave generated in the subject by the pulsed light irradiation. An object information acquisition method for acquiring a characteristic distribution in an object using
A signal processing step of acquiring a characteristic distribution in a subject using the electrical signal;
A control step of controlling an irradiation position of the pulse light so that the pulse light is not continuously irradiated to the subject from each of the first and second irradiation units;
Have
In the signal processing step,
An averaged signal or an averaged signal obtained by averaging or integrating an electrical signal caused by the pulsed light emitted from the first irradiation unit and an electrical signal caused by the pulsed light emitted from the second irradiation unit Acquiring the characteristic distribution in the object using the integrated signal, or
A distribution obtained using an electrical signal originating from the pulsed light emitted from the first irradiating unit, and a distribution obtained using an electrical signal originating from the pulsed light emitted from the second irradiating unit, An object information acquiring method characterized in that the above-mentioned synthesized is acquired as the characteristic distribution in the object.

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