JP6614910B2 - Photoacoustic device - Google Patents

Description

  The present invention relates to a photoacoustic apparatus using a photoacoustic effect.

  One of imaging techniques using light is a photoacoustic imaging technique. In photoacoustic imaging, first, pulsed light generated from a light source is irradiated onto a subject. Irradiation light propagates and diffuses in the subject, and is absorbed at a plurality of locations in the subject to generate photoacoustic waves. The transducer converts the photoacoustic wave into an electrical signal, and the processing device analyzes the electrical signal to acquire information on the optical characteristic value inside the subject.

The generated sound pressure (hereinafter also referred to as initial sound pressure) P ₀ of the photoacoustic wave generated from the light absorber in the subject can be expressed by the following equation.

P ₀ = Γ · μ _a · Φ (1)
Here, Γ is a Gruneisen coefficient, which is obtained by dividing the product of the volume expansion coefficient β and the square of the sound velocity c by the constant pressure specific heat C _p . Φ is the amount of light at a certain position (local area) (the amount of light reaching the absorber, also referred to as light fluence).

The initial sound pressure P ₀ can be obtained using a reception signal (PA signal) output from a probe that has received a photoacoustic wave.

If glue Nai Sen coefficients Kimare tissue, since it is known to take a substantially constant value, the optical absorption coefficient mu _a light quantity Φ by measuring and analyzing the temporal variation of PA signals at a plurality of locations The product, that is, the light energy absorption density can be obtained.

  Patent Literature 1 discloses a photoacoustic image generation apparatus that generates a photoacoustic image of a blood vessel based on a photoacoustic wave generated due to light.

JP2013-2448077A JP 2014-128455 A JP 2014-100284 A

Bin Luo and Sailing He, Optics Express, Vol. 15, Issue 10, pp. 5905-5918 (2007)

  By the way, when the measurement target is a living body, it is conceivable that a signal obtained by photoacoustic measurement is affected by the pulsation of the living body. For example, if the light absorber is hemoglobin, the signal acquired at the timing when the amount of blood in the blood vessel is large is large in the amount of hemoglobin present in the region to be measured, so the photoacoustic generated according to equation (1) The sound pressure of the waves increases. Therefore, it is expected that the S / N ratio of the obtained signal is relatively high. On the other hand, even if the same part is measured, the sound pressure of the generated photoacoustic wave is small because the signal acquired when the blood volume in the blood vessel is small is low in the amount of hemoglobin present in the part to be measured. Become. That is, it is expected that the S / N ratio of the received signal of the photoacoustic wave generated at the timing when the blood volume is small is relatively low. That is, the accuracy of the acquired subject information changes depending on the blood volume in the blood vessel.

  Therefore, an object of the present invention is to provide a photoacoustic apparatus capable of suppressing the influence on the acquired subject information due to the fluctuation of the blood volume in the blood vessel.

A photoacoustic apparatus according to one aspect of the present invention includes a light irradiation unit that irradiates a subject with pulsed light a plurality of times, and a photoacoustic generated by irradiating the subject with pulsed light from the light irradiation unit. A receiving unit that receives a wave and outputs a plurality of signals corresponding to a plurality of times of light irradiation; a blood information acquisition unit that acquires information about a blood volume of the subject; and the plurality of signals based on the plurality of signals. A subject information acquisition unit that acquires subject information in a region of interest in the sample, and the subject information acquisition unit is based on a plurality of signals acquired in a first period within each fluctuation period Obtaining first subject information, obtaining second subject information based on a plurality of signals obtained in a second period different from the first period within each fluctuation period, One subject information and the second subject information are superimposed and arranged in parallel. It is displayed on the display unit Te.

  According to the photoacoustic apparatus according to the present invention, it is possible to suppress the influence on the acquired object information due to the blood volume in the blood vessel.

Configuration diagram of photoacoustic apparatus according to embodiment The figure which shows the flowchart of the subject information acquisition method which concerns on Embodiment 1. FIG. The figure which shows the various sequences which concern on Embodiment 1. The figure which shows the flowchart of the subject information acquisition method which concerns on embodiment. The figure which shows the example of a display concerning Embodiment 2.

  Hereinafter, the present invention will be described in more detail with reference to the drawings. In addition, the same code | symbol is attached | subjected to the same component in principle, and description is abbreviate | omitted.

[Embodiment 1]
As described above, the S / N of the received signal of the photoacoustic wave generated in the region where the blood volume is small is relatively small. Therefore, when acquiring the subject information of the region of interest by the photoacoustic apparatus, there is a possibility that the accuracy of the subject information acquired in a period in which the blood volume is small may be reduced. Therefore, in the present embodiment, an example will be described in which the blood volume of the test part is estimated based on an electrocardiogram signal, and the subject information is acquired based on an acoustic wave generated during a period when the blood volume is relatively large.

  The photoacoustic apparatus according to the present embodiment is an apparatus that acquires subject information based on a photoacoustic wave reception signal. The subject information according to the present embodiment refers to information about the subject obtained from the received signal of the photoacoustic wave generated by the photoacoustic effect. Specifically, the subject information includes a generated sound pressure (initial sound pressure), a light energy absorption density, a light absorption coefficient, a concentration of a substance constituting the tissue, and the like. Here, the concentration of the substance includes oxygen saturation, oxyhemoglobin concentration, deoxyhemoglobin concentration, total hemoglobin concentration, and the like. The total hemoglobin concentration is the sum of the oxyhemoglobin concentration and the deoxyhemoglobin concentration. In addition, distribution data such as a light absorption coefficient distribution and an oxygen saturation distribution may be used as the subject information.

(Basic configuration)
A basic configuration of the photoacoustic apparatus according to the present embodiment will be described with reference to FIG.

  FIG. 1 is a schematic diagram showing the configuration of the photoacoustic apparatus of the present embodiment. The photoacoustic apparatus of this embodiment includes a light irradiation unit 110, an acoustic wave reception unit 130, an electrocardiogram acquisition unit 150, an input unit 170, a display unit 180, and a processing unit 190. The light irradiation unit 110 includes a light source 111 and an optical system 113. Details of these configurations will be described later.

  First, the pulsed light 112 from the light source 111 is guided to the optical system 113. The pulsed light 112 emitted from the optical system 113 is irradiated on the subject 120 and reaches the light absorber 121 in the subject 120. The light absorber 121 is typically a blood vessel in a living body, particularly a substance such as hemoglobin present in the blood vessel, a tumor, or the like. The light absorber 121 absorbs light energy and generates a photoacoustic wave 122. The generated photoacoustic wave 122 propagates through the subject and reaches the acoustic wave receiving unit 130.

  The acoustic wave receiving unit 130 receives the photoacoustic wave 122 and outputs a time-series reception signal. The processing unit 190 sequentially receives the reception signals output from the acoustic wave receiving unit 130. By performing the above steps a plurality of times of light irradiation, a plurality of time-series received signals corresponding to the plurality of times of light irradiation can be obtained.

  The processing unit 190 generates subject information in the region of interest using a plurality of input time-series received signals. Then, the processing unit 190 transmits the generated subject information data to the display unit 180, and causes the display unit 180 to display an image or numerical value of the subject information in the region of interest. The region of interest may be set in advance, or the user may input the region of interest using the input unit 170. The region of interest is set so as to include at least a part of the subject 120. Details of the method for acquiring subject information will be described later.

  By the way, when hemoglobin is assumed as the light absorber, since the amount of hemoglobin is small in a region where the blood volume in the blood vessel is small, the light absorption coefficient in that region is relatively low. Therefore, the sound pressure of the photoacoustic wave generated according to the equation (1) is reduced. That is, the S / N of the received signal of the photoacoustic wave generated in the region where the blood volume is small is relatively small. Further, when the amount of blood is extremely small, the photoacoustic wave reception signal may be buried in noise. For this reason, when the subject information of the region of interest is acquired by the photoacoustic apparatus, the accuracy of the acquired subject information may be reduced in a region where the blood volume is small.

  In view of the above problems, the photoacoustic apparatus according to the present embodiment includes an electrocardiogram acquisition unit 150 that acquires an electrocardiogram signal of the subject 120. The heart state of the subject 120 can be estimated from the waveform of the electrocardiogram signal obtained by the electrocardiogram acquisition unit 150, and the blood flow state of the subject 120 can be estimated. Therefore, based on the electrocardiogram signal of the subject 120, the processing unit 190 receives a photoacoustic wave reception signal generated when the amount of blood in the region of interest is small among a plurality of reception signals corresponding to a plurality of times of light irradiation. The object information in the region of interest is acquired without using it. That is, the processing unit 190 uses at least a part of the received signal of the photoacoustic wave generated when the blood volume in the region of interest is large among the plurality of received signals corresponding to the plurality of times of light irradiation. The subject information at is acquired. In the present embodiment, the electrocardiogram acquisition unit corresponds to the blood information acquisition unit.

  By extracting the signal used for the subject information in this way, the photoacoustic wave having a high S / N generated when the blood volume is large, that is, when the amount of hemoglobin as the light absorber is large. Object information can be acquired using many received signals. In addition, according to the present embodiment, since the subject information can be acquired without using the received signal of the photoacoustic wave having a low S / N generated in a state where the blood volume is low, the subject in the region of interest can be obtained. Information can be acquired with high accuracy. Details of the signal extraction timing will be described later.

  Hereinafter, each component block of the photoacoustic apparatus according to the present embodiment will be described.

(Light source 111)
The light source 111 is preferably a pulsed light source capable of generating pulsed light on the order of nanoseconds to microseconds. A specific pulse width is preferably about 1 to 100 nanoseconds. The wavelength is preferably in the range of about 400 nm to 1600 nm. In particular, when imaging a blood vessel near the surface of a living body with high resolution, light having a wavelength in the visible light region (400 nm or more and 700 nm or less) is preferable. On the other hand, when imaging a deep part of a living body, it is preferable to use light having a wavelength (700 nm or more and 1100 nm or less) that is less absorbed in the background tissue of the living body. However, it is possible to use terahertz waves, microwaves, and radio waves.

  As the specific light source 111, a laser is preferable. Moreover, when measuring using light of a plurality of wavelengths, a laser capable of converting the oscillating wavelength is more preferable. When irradiating the subject 120 with a plurality of wavelengths, it is also possible to use a plurality of lasers that oscillate light of different wavelengths while irradiating each of them or alternately irradiating them. When multiple lasers are used, they are collectively expressed as a light source.

  As the laser, various lasers such as a solid laser, a gas laser, a dye laser, and a semiconductor laser can be used. In particular, a pulsed laser such as an Nd: YAG laser or an alexandrite laser is preferable. Further, a Ti: sa laser or an OPO (Optical Parametric Oscillators) laser using Nd: YAG laser light as excitation light may be used. In addition, a light emitting diode or the like can be used instead of the laser.

(Optical system 113)
The optical system 113 transmits the pulsed light 112 from the light source 111 to the subject 120. An optical element such as a lens, a mirror, or an optical fiber can be used for the optical system 113. Further, the optical system 113 according to the present embodiment includes an optical mirror 114 for changing the traveling direction of the pulsed light 112, a light control unit 115, and a diffusion plate 116.

  In a biological information acquisition apparatus using a breast or the like as a subject, it is preferable that the light emitting portion of the optical system 113 is irradiated with the beam diameter of the pulsed light expanded by the diffusion plate 116 or the like. On the other hand, in the photoacoustic microscope, in order to increase the resolution, it is preferable that the light emitting portion of the optical system 113 is composed of a lens or the like, and the beam diameter is focused for irradiation.

  In addition, the optical system 113 can include a light control unit 115 that can adjust the attenuation amount of the pulsed light 112 emitted from the light source 111. As the light control unit 115, any means that can adjust the attenuation amount of the pulsed light 112 such as a mechanical shutter and a liquid crystal shutter can be used.

  Further, the optical system 113 may be moved with respect to the subject 120, thereby enabling imaging of the subject 120 over a wide range.

  Note that it is also possible to directly irradiate the subject 120 with light from the light source 111 without using the optical system 113.

(Subject 120)
The subject 120 does not constitute a part of the photoacoustic apparatus of the present invention, but will be described below. The main purpose of the photoacoustic apparatus according to the present embodiment is to diagnose malignant tumors and vascular diseases in humans and animals, and to observe the course of chemotherapy. Therefore, the subject 120 is assumed to be a living body, specifically, a target site for diagnosis such as the breast, neck, and abdomen of a human body or animal.

  In addition, as the light absorber 121 inside the subject 120, one having a relatively high light absorption coefficient inside the subject 120 is preferable. For example, if the human body is a measurement target, oxyhemoglobin or deoxyhemoglobin, a blood vessel containing many of them, or a new blood vessel formed in the vicinity of a tumor is the target of the light absorber 121.

(Acoustic wave receiving unit 130)
The acoustic wave receiving unit 130 includes one or more conversion elements and a casing. The conversion element includes a piezoelectric element using a piezoelectric phenomenon such as lead zirconate titanate (PZT), a conversion element using optical resonance, a capacitive conversion element such as a capacitive micromachined ultrasonic transducer (CMUT), and the like. Any conversion element that can receive a wave and convert it into an electrical signal may be used. In the case of including a plurality of conversion elements, it is preferable that they are arranged in a plane or curved surface called a 1D array, 1.5D array, 1.75D array, or 2D array.

  In order to acquire subject information in a wide range, the acoustic wave receiving unit 130 is preferably configured to mechanically move with respect to the subject 120 by a scanning mechanism (not shown). Moreover, it is preferable that the optical system 113 (irradiation position of the pulsed light 112) and the acoustic wave receiving unit 130 move in synchronization.

  In the case of the handheld acoustic wave receiving unit 130, the user has a gripping unit that grips the acoustic wave receiving unit 130. An acoustic lens may be provided on the reception surface of the acoustic wave receiving unit 130. In addition, the acoustic wave receiving unit 130 may be provided with a plurality of conversion elements.

  The acoustic wave receiving unit 130 may be provided with an amplifier that amplifies a time-series analog signal output from the conversion element.

(ECG acquisition unit 150)
The electrocardiogram acquisition unit 150 acquires an electrocardiogram signal of the subject 120. Typically, the electrocardiogram acquisition unit 150 includes an induction electrode that extracts an electrocardiogram signal, an amplifier, an A / D converter, and the like. For example, as the electrocardiogram acquisition unit 150, the device described in Patent Document 2 or Patent Document 3 can be used. According to the electrocardiogram signal obtained by the electrocardiogram acquisition unit 150, the heart state of the subject 120 can be estimated. It is also possible to estimate the blood flow in the blood vessel from the form of the heart estimated from the electrocardiogram signal.

(Input unit 170)
The input unit 170 receives various inputs from a user (mainly an inspector such as a medical worker) and transmits the input information to the configuration of the processing unit 190 and the like via the system bus. For example, the input unit 170 allows the user to perform image processing operations related to images, such as parameter settings related to imaging, an instruction to start imaging, and observation parameter settings such as the range and shape of a region of interest.

  The input unit 170 includes a mouse, a keyboard, a touch panel, and the like, and notifies an event to software such as an OS operating on the control unit 193 according to a user operation. Further, the handheld photoacoustic apparatus is preferably provided with an input unit 170 for instructing driving of the light irradiation unit 110. As such an input unit 170, a button-type switch or a foot switch provided on the probe can be employed.

(Display unit 180)
As the display unit 180, a display such as an LCD (Liquid Crystal Display), a CRT (Cathode Ray Tube), or an organic EL display can be used. Note that the display unit 180 may be separately prepared and connected to the photoacoustic apparatus without being configured to be included in the photoacoustic apparatus of the present embodiment.

(Processing unit 190)
The processing unit 190 as a computer includes a calculation unit 191, a storage unit 192, and a control unit 193.

  The arithmetic unit 191 collects time-series analog reception signals output from the acoustic wave reception unit 130, and performs signal processing such as amplification of the reception signal, AD conversion of the analog reception signal, and storage of the digitized reception signal I do. As the arithmetic unit 191 that performs such processing, a circuit generally called a DAS (Data Acquisition System) can be used. Specifically, the arithmetic unit 191 includes an amplifier that amplifies a received signal, an AD converter that digitizes an analog received signal, and the like.

  Moreover, the calculating part 191 can acquire the generated sound pressure information of each position in the subject using the received signal. The generated sound pressure information at each position in the subject is also referred to as an initial sound pressure distribution in the subject. When the photoacoustic apparatus is a photoacoustic tomography apparatus, the calculation unit 191 performs image reconstruction using the obtained reception signal, thereby generating sound corresponding to a position on a two-dimensional or three-dimensional spatial coordinate. Pressure data can be obtained. The calculation unit 191 can use a known reconstruction method such as Universal Back Projection (UBP), Filtered Back Projection (FBP), or a model-based method as an image reconstruction method. Further, the arithmetic unit 191 may use a delay and sum process as an image reconstruction method.

  In addition, the calculation unit 191 performs envelope detection on the obtained reception signal with respect to time change, and then calculates the amplitude value in the time axis direction of the signal after envelope detection for each optical pulse in the depth direction of the conversion element. It may be converted and plotted in the pointing direction (typically in the depth direction) in spatial coordinates. The calculation unit 191 can acquire initial sound pressure distribution data by performing this for each position of the conversion element. In particular, this method is preferably used when the photoacoustic apparatus is a photoacoustic microscope.

  An arithmetic circuit such as a CPU or GPU (Graphics Processing Unit), or an FPGA (Field Programmable Gate Array) chip can be used as the arithmetic unit 191 that performs processing for acquiring the generated sound pressure information. Note that the arithmetic unit 191 is not limited to a single processor or arithmetic circuit, but may be configured from a plurality of processors or arithmetic circuits.

  The storage unit 192 can store received signals after AD conversion, various distribution data, display image data, various measurement parameters, and the like. In addition, each process performed by the object information acquisition method described later can be stored in the storage unit 192 as a program that is executed by the control unit 193 in the processing unit 190. Note that the storage unit 192 in which the program is stored is a non-temporary recording medium. The storage unit 192 typically includes a storage medium such as a FIFO memory, a ROM, a RAM, and a hard disk. Note that the storage unit 192 may be configured not only from one storage medium but also from a plurality of storage media.

  In addition, the processing unit 190 includes a control unit 193 for controlling the operation of each component block of the photoacoustic apparatus. The control unit 193 supplies necessary control signals and data to each constituent block of the photoacoustic apparatus via the bus. Specifically, the control unit 193 supplies a light emission control signal that instructs the light source 111 to emit light, a reception control signal of a conversion element in the acoustic wave reception unit 130, and the like. The control unit 193 typically uses a CPU.

  In addition, each structure with which the process part 190 is provided may be comprised by the integral apparatus, and may be comprised by another apparatus, respectively. Moreover, the calculating part 191 and the control part 193 may be comprised by the single device. That is, the processing unit 190 may include a single device that functions as the calculation unit 191 and the control unit 193.

[Subject information acquisition method]
Next, a flow in which the photoacoustic apparatus according to the present embodiment acquires object information will be described with reference to FIG. The control unit 193 reads out a program describing the subject information acquisition method stored in the storage unit 192, and causes the photoacoustic apparatus to execute the following subject information acquisition method.

(S100: Step of acquiring a photoacoustic wave reception signal by multiple times of light irradiation)
In this step, the light irradiation unit 110 irradiates the subject 120 with the pulsed light 112. Subsequently, the acoustic wave receiving unit 130 receives the photoacoustic wave 122 generated by the irradiation of the pulsed light 112 and outputs a time-series analog reception signal. The arithmetic unit 191 collects time-series analog reception signals output from the acoustic wave reception unit 130 and performs amplification processing of the reception signals and AD conversion processing of the analog reception signals. Then, the calculation unit 191 stores the digitized reception signal in the storage unit 192. The time-series received signal data stored in the storage unit 192 is also referred to as photoacoustic data. In the present invention, the received signal is a concept including both an analog signal and a digital signal.

  Further, in this step, the light irradiation unit 110 performs light irradiation a plurality of times, whereby a plurality of time-series received signals corresponding to the plurality of light irradiations are stored in the storage unit 192.

  In the case where the light source 111 is a solid laser or the like that is easily pumped by heat, it is preferable to emit light at a constant repetition frequency and irradiate the subject 120 a plurality of times for stable driving of the light source. FIG. 3A shows a driving sequence of the light source 111 according to this embodiment. As shown in FIG. 3A, in the present embodiment, the light source 111 emits light at a predetermined repetition frequency (about 5 Hz).

(S200: Step of acquiring an electrocardiogram signal during a plurality of times of light irradiation)
In this step, the electrocardiogram acquisition unit 150 acquires an electrocardiogram signal of the subject 120 and transmits it to the processing unit 190. The electrodes provided in the electrocardiogram acquisition unit 150 are appropriately arranged so that an electromyogram signal (electrocardiogram signal) related to the heart can be acquired.

  FIG. 3B shows a typical ECG signal waveform obtained by the ECG acquisition unit 150. The electrocardiogram signal shown in FIG. 3 (b) has a waveform with a period of about 1.2 seconds. Typically, the waveform of an electrocardiogram signal is formed by combining a P wave, a Q wave, an R wave, an S wave, and a T wave. In general, the period from the top of the R wave to the vicinity of the end of the T wave corresponds to the ventricular systole, and blood is pumped into the artery. The period from the vicinity of the end of the T wave to the top of the R wave corresponds to the ventricular diastole. In this specification, the time t1 from the top of the R wave to the vicinity of the end of the T wave is referred to as “first time from the R wave generation timing to the T wave generation timing”.

  FIG. 3C is a graph showing changes in blood volume in the region of interest. As described above, in the heart mode, the ventricle contraction is triggered by the R wave of the electrocardiogram signal, and the delivery to the artery is started. However, as can be understood from FIG. 3C, the blood volume in the region of interest does not increase at the generation timing of the R wave, but the blood flow corresponding to the ventricular contraction in the region of interest from the generation timing of the R wave. It increases with a time difference by the time t2 until it reaches. Then, after the time t2 has elapsed from the generation timing of the R wave, it is considered that the period in which the blood volume is high is maintained for the time t1 of the ventricular contraction period.

  In this specification, the time t2 from when the R wave is generated until the blood flow corresponding to the ventricular contraction reaches the region of interest is also referred to as “delay time”.

(S300: step of extracting a received signal obtained when the blood volume in the region of interest is large based on the electrocardiogram signal)
In this step, the calculation unit 191 serving as the subject information acquisition unit uses the electrocardiogram signal obtained in S200 based on the electrocardiogram signal obtained in S200 from a plurality of time-series received signals corresponding to the plurality of times of light irradiation obtained in S100. A signal used for acquiring specimen information is extracted.

  Based on the electrocardiogram signal obtained by the electrocardiogram acquisition unit 150, the calculation unit 191 determines the timing when the blood volume in the region of interest is large. Then, the arithmetic unit 191 reads out a photoacoustic wave reception signal generated at the timing from the storage unit 192. On the other hand, the calculation unit 191 does not read out the received signal of the photoacoustic wave generated at the timing when the blood volume in the region of interest is small from the storage unit 192 and does not use it for acquiring the subject information.

  FIG. 3D shows a signal extraction sequence performed by the arithmetic unit 191 and indicates that the arithmetic unit 191 extracts a received signal obtained when “read”. The arithmetic unit 191 is a period from the time when the R wave of the electrocardiogram signal is generated to the time when the time t1 of the ventricular systole passes after the R wave generation timing of the electrocardiogram signal among the plurality of time series received signals obtained in S100. A received signal of the generated photoacoustic wave is extracted. That is, the calculation unit 191 reads, from the storage unit 192, a photoacoustic wave reception signal generated by irradiating light during a period in which blood flow due to electrical stimulation exists in the region of interest and the amount of blood is large. On the other hand, the calculation unit 191 does not read out from the storage unit 192 a photoacoustic wave reception signal generated by light irradiation during a period other than the period in which the blood volume is large.

  The signal extracted in this step is a received photoacoustic wave signal generated at the timing when the blood volume increases due to ventricular contraction. For this reason, the extracted signal contains many signals with high S / N.

  Since the speed of light is orders of magnitude faster than the speed of photoacoustic waves, it can be considered that photoacoustic waves are generated simultaneously at each position in the region of interest at the timing when the pulsed light 112 is irradiated. In this specification, the timing at which the subject 120 is irradiated with the pulsed light 112 is defined as the timing at which the photoacoustic wave generated by the pulsed light 112 is generated.

  Further, it is typically known that the time t1 from the generation timing of the R wave to the generation timing of the T wave is a time of 0.3 seconds or more and 0.45 seconds or less. Therefore, the calculation unit 191 receives a photoacoustic wave reception signal generated at a predetermined time of 0.3 second or more and 0.45 second or less after the time t2 has elapsed from the generation timing of the R wave as a period in which the blood volume is large. May be read from the storage unit 192.

  Here, the calculation unit 191 can detect the generation timing of a specific wave such as an R wave or a T wave from the electrocardiogram signal. For example, the calculation unit 191 can detect a wave of an electrocardiogram signal larger than a predetermined amplitude as an R wave. Further, for example, the calculation unit 191 performs template matching with an R wave or T wave template waveform stored in the storage unit 192 for the electrocardiogram signal and detects a wave having a high similarity as an R wave or T wave. Can do. In addition, as a method of detecting a specific wave, any method may be used as long as a characteristic waveform such as an R wave or a T wave can be detected.

  Note that blood flow corresponding to ventricular contraction reaches the region of interest after a time corresponding to the value obtained by dividing the blood vessel length between the heart and the region of interest by the blood flow velocity after the R wave is generated. Therefore, the calculation unit 191 starts extraction of a signal to be used for acquiring the subject information based on the generation timing of the R wave, information on the blood vessel length between the heart and the region of interest, and information on the blood flow velocity. Can be determined. However, in order to determine the extraction start timing of the signal to be used as described above, it is necessary to measure the distance between the heart and the region of interest and the blood flow velocity for each subject. There is.

  Therefore, it is preferable to select the extraction start timing from those predetermined for each region of the region of interest. That is, it is preferable that the storage unit 192 includes a relationship table between the type of region of the region of interest and the delay time t2. Moreover, it is preferable that the photoacoustic apparatus has an input unit 170 configured so that the user can input the type of the region of the region of interest. For example, the input unit 170 can be configured such that the user can select the type of the region of interest from the plurality of types of regions displayed on the display unit 180. Then, the calculation unit 191 can read the delay time t <b> 2 corresponding to the type of the part input by the input unit 170 from the relation table stored in the storage unit 192. The calculation unit 191 detects the generation timing of the R wave from the electrocardiogram signal, and extracts a desired signal from the received photoacoustic wave signal generated after the delay time t2 read from the storage unit 192 has elapsed from that timing. be able to.

  Here, the description has been made using the type of region of the region of interest as the information necessary for determining the delay time t2. However, the information necessary for determining the delay time t2 is not limited thereto. For example, even if the type of region of interest is the same, the delay time t2 is considered to change depending on the age of the subject. Therefore, it is preferable that the input unit 170 is configured to be able to input information such as the age of the subject in addition to the type of part. That is, it is preferable that the input unit 170 is configured to be able to input at least the type of region of interest. The control unit 193 preferably reads out the delay time t2 corresponding to the input information such as the age of the subject from the relation table.

  Moreover, when the target site | part of a photoacoustic apparatus is decided beforehand, it is preferable that the memory | storage part 192 preserve | saves the information of the delay time t2 calculated | required beforehand. Then, the calculation unit 191 detects the generation timing of the R wave from the electrocardiogram signal, and extracts a desired signal from the photoacoustic wave reception signal generated after the delay time t2 stored in the storage unit 192 from the timing. be able to.

  When the period from the generation timing of the R wave until the blood flow corresponding to the ventricular contraction reaches the region of interest can be ignored, the generation timing of the R wave may be set as the extraction start timing. That is, in this case, the delay time t2 = 0 may be set.

  In this embodiment, the extraction amount of the received signal is set in consideration of the fact that the blood volume increases during the time t1 of the ventricular systole after the delay time t2 has elapsed from the generation timing of the R wave. Is not limited to this form. For example, the time t1 corresponds to the time of the ventricular systole, but depending on the amount of stored blood, most of the blood delivery may be completed before the time t1 elapses. That is, there may be a case where the time of the ventricular systole does not match the time required for blood delivery. In this case, there is a possibility that the blood volume increases only for a time shorter than the time t1. In this case, the processing unit 190 acquires subject information using at least a part of the received photoacoustic wave signal generated after the delay time t2 elapses from the R wave generation timing until the time t3 elapses. It is preferable to do. That is, the processing unit 190 is obtained until half of the time t1 elapses among the received signals obtained until the voltage application time t1 elapses after the delay time t2 elapses from the generation timing of the R wave. It is preferable to use many received signals.

  Further, for example, even during the time t1 after the delay time t2 has elapsed from the generation timing of the R wave, the S / N of the received signal acquired is sufficient at the timing when the increase in blood volume is not sufficiently large. In some cases, it may not be large. Therefore, it is preferable that the calculation unit 191 extracts a reception signal whose amplitude is larger than a predetermined value during the voltage application time t1 after the delay time t2 has elapsed from the generation timing of the R wave. As a result, it is possible to selectively extract a received signal having a particularly high S / N during the period in which the blood volume increases.

  Note that the sequence shown in FIG. 3D is not only executed in real time in parallel with the sequence shown in FIGS. 3A to 3C, but also the sequence shown in FIGS. It may be performed after the sequence is complete.

  In the present embodiment, a desired signal is extracted from a plurality of time-series received signals stored in the storage unit 192. However, as long as the object information can be acquired by selectively using the desired signal, this method is used. Not limited to. For example, among the analog electrical signals output from the acoustic wave receiving unit 130, those corresponding to the received photoacoustic wave signal generated when the blood volume is small may not be stored in the storage unit 192. As a result, the storage unit 192 selectively stores a photoacoustic wave reception signal generated when the blood volume is large. Then, the calculation unit 191 may acquire subject information by selectively using a photoacoustic wave reception signal generated when the amount of blood stored in the storage unit 192 is large.

(S400: Step of acquiring subject information in the region of interest based on the extracted received signal)
In this step, the calculation unit 191 acquires subject information in the region of interest based on the reception signal extracted in S300. In the present embodiment, the calculation unit 191 calculates photoacoustic wave generated sound pressure information at each position in the region of interest, that is, initial sound pressure distribution, as subject information, and stores it in the storage unit 192.

  Since the initial sound pressure distribution obtained in this step is calculated based on the signal having a high S / N extracted in S300, the accuracy is high. Therefore, when the calculation unit 191 displays the image of the initial sound pressure distribution stored in the storage unit 192 on the display unit 180, an image with high image quality such as resolution and contrast can be provided to the user.

  The calculation unit 191 may calculate the light fluence of the pulsed light 112 that has reached each position in the region of interest, that is, the light amount distribution. In the present embodiment, the calculation unit 191 obtains information on the light amount distribution in the region of interest of the pulsed light 112 by solving the light diffusion equation described in Non-Patent Document 1, and stores it in the storage unit 192. it can. Note that the calculation unit 191 may acquire the light amount distribution by any technique as long as the light amount distribution in the region of interest can be acquired.

  Subsequently, the calculation unit 191 uses the initial sound pressure distribution and the light amount distribution in the region of interest stored in the storage unit 192, and uses the light absorption coefficient distribution in the region of interest as subject information according to Expression (1). You may get it.

  In this step, the computing unit 191 may acquire one frame of subject information from the time-series received signal obtained by one pulse of light irradiation among the signals extracted in S300. In addition, the calculation unit 191 may acquire one frame of subject information from a plurality of time-series received signals obtained by a plurality of times of light irradiation among the signals extracted in S300. In other words, the calculation unit 191 may acquire the subject information using at least a part of the received photoacoustic wave signal generated when the blood volume is large.

  With the above-described object information acquisition method, the influence of the blood volume in the blood vessel on the accuracy of the acquired object information can be suppressed.

  In addition, the photoacoustic apparatus which concerns on this embodiment can also acquire light absorption coefficient distribution similarly by performing each said step using the light of a different wavelength. And the calculating part 191 can also acquire the information of the concentration distribution of the substance which comprises the test object 120 as test object information using the light absorption coefficient distribution corresponding to the light of a mutually different several wavelength.

  However, when light of each of a plurality of wavelengths is generated using a single light source, it may take time to switch wavelengths. Here, if the wavelength is switched when the blood volume is large, the number of times that light can be irradiated during the state where the blood volume is large may decrease, leading to a decrease in accuracy of the subject information. . Therefore, it is preferable to switch the wavelength when the blood volume is low. For example, when one period is from one R wave to the next R wave, the light irradiation unit 110 emits light having the first wavelength λ1 during one period of the electrocardiogram signal. Subsequently, during a period when the blood volume in the cycle is small, the wavelength variable mechanism in the light source 111 is driven so that the light source 111 can generate light having the second wavelength λ2. Subsequently, within the next period, the light irradiation unit 110 irradiates the subject 120 with light having the second wavelength λ2.

  In this way, the wavelength can be switched during a period when the blood volume is small and the reception signal is determined not to be used. Thereby, it is possible to efficiently irradiate light of a plurality of wavelengths when the amount of blood is large without reducing the number of times of light irradiation in a period in which it is determined that the received signal should be used because of a large amount of blood. . In the present embodiment, since a signal that can be extracted for acquiring the subject information can be efficiently secured, the accuracy of obtaining the subject information can be improved efficiently.

  As described above, in the present embodiment, based on a plurality of received signals acquired in a common period within each fluctuation cycle of a blood volume fluctuation cycle that is repeated a plurality of times with the pulsation of the subject. Subject information is acquired. Since the subject information is acquired from the reception signals having the same timing, it is possible to suppress the influence on the acquired subject information due to fluctuations in blood volume. In particular, since a received signal acquired during a period in which the blood volume is large even within the fluctuation period as in this embodiment is used, an image with high accuracy of subject information can be obtained.

[Embodiment 2]
Next, Embodiment 2 will be described.

  In the first embodiment, the subject information is generated only from the received signal acquired during the period in which the blood volume is high. However, it is conceivable that the user has a desire to observe the test part in the period in which the blood volume is low. Therefore, in the present embodiment, a case will be described in which a reception signal obtained during a period of low blood volume that is not used in the acquisition of the subject information in the first embodiment is acquired, and the subject information is acquired based on this. .

  The configuration of the photoacoustic apparatus according to the present embodiment is the same as the configuration described in the first embodiment.

  Next, a flow in which the photoacoustic apparatus according to the present embodiment acquires object information will be described with reference to FIG. S100 and S200 are the same as those in the first embodiment.

(S500: a step of extracting a received signal obtained when the blood volume in the region of interest is large based on the electrocardiogram signal as a received signal 1 and a received signal obtained at other timing as a received signal 2)
In this step, the calculation unit 191 serving as the subject information acquisition unit uses the electrocardiogram signal obtained in S200 based on the electrocardiogram signal obtained in S200 from a plurality of time-series received signals corresponding to the plurality of times of light irradiation obtained in S100. A signal used for acquiring specimen information is extracted.

  Based on the electrocardiogram signal obtained by the electrocardiogram acquisition unit 150, the calculation unit 191 estimates a period during which the blood volume in the region of interest is large. Then, the calculation unit 191 reads the received signal of the photoacoustic wave generated during that period from the storage unit 192 as the received signal 1. On the other hand, the calculation unit 191 reads the received signal of the photoacoustic wave generated at the timing when the blood volume in the region of interest is small as the received signal 2 from the storage unit 192. That is, the arithmetic unit 191 extracts the received signal obtained when “read” in FIG. 3D as the first received signal, and receives the received signal obtained when not “read” as the second received signal. Extract as a signal. Thus, each received signal extracted by dividing it into a plurality of received signals is called a received signal group.

  As the signals extracted in this step, the photoacoustic wave generated at the timing when the blood volume increases due to ventricular contraction and the photoacoustic wave generated at the timing when the blood volume decreases due to ventricular expansion are read out as separate received signals. Therefore, the variation in blood volume at the time when each signal is generated in each received signal group is reduced.

(S600: Obtain and display subject information in the region of interest based on the extracted first received signal and second received signal)
In this step, the calculation unit 191 acquires subject information in the region of interest based on each of the first and second received signals extracted in S500. In the present embodiment, the calculation unit 191 calculates photoacoustic wave generated sound pressure information at each position in the region of interest, that is, initial sound pressure distribution, as subject information, and stores it in the storage unit 192.

  As described in the first embodiment, the subject information is not limited to the initial sound pressure distribution, but may be information on a light absorption coefficient distribution or a concentration distribution of a substance constituting the subject 120.

  As for the light absorption coefficient distribution and the substance concentration distribution, a method is known in which numerical values obtained by multiple laser irradiations are averaged to increase the S / N of the numerical values. On the other hand, since the light absorption coefficient distribution and the substance concentration distribution are proportional to the amount of hemoglobin, it can be said to be proportional to the blood volume. Therefore, the subject obtained from each of the first received signal and the second received signal, rather than the average of the subject information obtained from the plurality of received signals acquired regardless of the blood volume in the blood vessel. By averaging each information, it is possible to obtain subject information with a smaller variation in blood volume.

  Next, a display method of the obtained subject information will be described with reference to FIG.

  An area 220 is an area for displaying an image of an initial sound pressure distribution generated from the first received signal, and an area 221 is an area for displaying an image of the initial sound pressure distribution generated from the second received signal. is there. Since the initial sound pressure distribution is generally obtained as a 3D image, a 3D image may be displayed at the time of display, or a cross section of the 3D image, a range of MIP (Maximum Intensity Projection) images, or the like may be displayed. Also good.

  The area 200 is an area for displaying a range to be extracted as the first received signal and a range to be extracted as the second received signal. A range 204 is a range representing the time t2 described in the first embodiment, and a range 205 is a range representing the time t1 described in the first embodiment. A range 201 represents a period between the start of the P wave and the time when the time t2 has elapsed from the apex of the R wave, and is a range that is extracted as the second received signal. A range 202 represents the time t1 and is a range that is extracted as the first received signal. A range 203 represents a range from the end of time t1 to the start of the P wave, and is extracted as a second received signal. A typical electrocardiogram waveform may be displayed in the background of the region 200 to make it easier for the user to understand. Further, the latest electrocardiogram waveform actually acquired by the electrocardiogram acquisition unit 150 may be displayed. Note that a typical ECG waveform or the latest ECG waveform may be displayed side by side with the region 200.

  Item 210 is a UI part that can input and change time t1. The item 211 is a UI part that can input and change the time t2. The width of the range 205 and the range 204 may be changed in conjunction with the change of the item 210 and the item 211. Further, in conjunction with the change of the item 201 and the item 211, the extraction processing of the first and second received signals in step 500 is executed again based on the newly set times t1 and t2. Further, the subject information is acquired again, and the images displayed in the area 220 and the area 221 are updated. In the example shown in FIG. 5, when the user selects the upper and lower triangles shown as the item 210, the length of the time t <b> 1 shown in the text box is updated, and the dotted line indicating the time t <b> 1 is also displayed on the area 200. The distance between is changed. The user may directly enter a number in the text box, or set the range of time t1 by determining the start and end times of time t1 by dragging the dotted line in area 200 with a mouse or the like. Also good. The time t2 may be set by the same method as the time t1.

  The object information to be displayed is not limited to the initial sound pressure distribution, but may be a light absorption coefficient distribution or a substance concentration distribution.

  In the present embodiment, one cycle of the electrocardiogram waveform is indicated by a period in which the blood volume is high (period indicated by (1) in FIG. 5) and a period in which the blood volume is low ((2) in FIG. 5). In this example, the period is divided into two or more sections. As one cycle is divided into more sections, the variation in blood volume in each section becomes smaller, and thus a reception signal with a more uniform signal level can be obtained. On the other hand, if the number of divisions of the electrocardiogram waveform is increased, the number of received signals obtained in each section is reduced, so that the effect of improving the S / N by averaging them is reduced. In view of this trade-off, it is desirable to determine how many periods are divided.

  In the present embodiment, the image based on the first received signal and the image based on the second received signal are displayed side by side, but other display methods may be used. As an example, it can be considered that two images are superimposed and displayed. Moreover, you may display an image alternately. When the number of divisions of the electrocardiogram waveform is increased, it can be displayed like a moving image. This is because an image obtained by averaging received signals obtained by multiple irradiations is sequentially displayed, so that the initial sound pressure distribution obtained from the received signals obtained by one laser irradiation is sequentially displayed as a moving image. Thus, it is possible to provide a user with a moving image based on an image having a higher S / N ratio.

  In this embodiment, the acquisition and display of the subject information are performed after the acquisition of the photoacoustic wave signal and the electrocardiogram signal. Information acquisition and display may be performed in real time. In addition, when acquiring and displaying subject information in real time, not all photoacoustic wave signals and ECG signals from the start of acquisition are used, but some photoacoustic wave signals and ECG signals are used. May be. For example, it is conceivable to use a photoacoustic wave signal and an electrocardiogram signal acquired during a period from a current time to a current time. In this way, more accurate subject information can be obtained even when the subject has moved.

  According to the second embodiment described above, the same effect as in the first embodiment can be obtained. Furthermore, according to the present embodiment, it is possible to provide the user with subject information for each different period of the blood volume fluctuation cycle. The arteries are beating at the timing when the blood volume increases, and it is considered that the arteries and veins can be distinguished by comparing these pieces of subject information.

[Others]
The present invention has been described in detail above with reference to specific embodiments. However, the present invention is not limited to the specific form described above, and the embodiments can be modified without departing from the technical idea of the present invention.

  For example, in the above description, the case where an electrocardiograph is used as the blood information acquisition unit for grasping the increase or decrease in the blood volume at the measurement site has been described. However, the blood volume at the measurement site is measured by other means for measuring the pulsation of the subject. You may know. For example, an infrared pulse meter may be used.

DESCRIPTION OF SYMBOLS 110 Light irradiation part 120 Subject 130 Acoustic wave receiving part 150 Electrocardiogram acquisition part 190 Processing part

Claims (10)

A light irradiation unit that irradiates the subject with pulsed light multiple times;
Receiving a photoacoustic wave generated by irradiating the subject with pulsed light from the light irradiation unit, and outputting a plurality of signals corresponding to a plurality of times of light irradiation; and
A blood information acquisition unit for acquiring information on the blood volume of the subject;
A subject information acquisition unit that acquires subject information in a region of interest in the subject based on the plurality of signals;
Have
The subject information acquisition unit includes:
Acquiring first subject information based on a plurality of signals acquired in the first period within each fluctuation period, and acquiring in a second period different from the first period in each fluctuation period Obtaining second subject information based on the plurality of signals obtained,
The first thing to be displayed in superposition to alongside Table radical 113 and object information and said second object information, the photoacoustic device you characterized. A light irradiation unit that irradiates the subject with pulsed light multiple times;
Receiving a photoacoustic wave generated by irradiating the subject with pulsed light from the light irradiation unit, and outputting a plurality of signals corresponding to a plurality of times of light irradiation; and
A blood information acquisition unit for acquiring information on the blood volume of the subject;
Subject information acquisition for acquiring subject information in a region of interest in the subject based on the plurality of signals acquired in a common period within each fluctuation cycle of the blood volume fluctuation cycle repeated a plurality of times And
Have
The subject information acquisition unit includes:
Wherein causing information indicating the common period of the object information and the in each variation period appear in Table radical 113, photoacoustic devices it said. A light irradiation unit that irradiates the subject with pulsed light multiple times;
Receiving a photoacoustic wave generated by irradiating the subject with pulsed light from the light irradiation unit, and outputting a plurality of signals corresponding to a plurality of times of light irradiation; and
A blood information acquisition unit for acquiring information on the blood volume of the subject;
Subject information acquisition for acquiring subject information in a region of interest in the subject based on the plurality of signals acquired in a common period within each fluctuation cycle of the blood volume fluctuation cycle repeated a plurality of times And
Have
The blood information acquisition unit
An electrocardiogram acquisition unit for acquiring an electrocardiogram signal of the subject;
The subject information acquisition unit includes:
Possible to display the object information and the ECG signal in Table radical 113, photoacoustic devices it said. A light irradiation unit that irradiates the subject with pulsed light multiple times;
Receiving a photoacoustic wave generated by irradiating the subject with pulsed light from the light irradiation unit, and outputting a plurality of signals corresponding to a plurality of times of light irradiation; and
A blood information acquisition unit for acquiring information on the blood volume of the subject;
Subject information acquisition for acquiring subject information in a region of interest in the subject based on the plurality of signals acquired in a common period within each fluctuation cycle of the blood volume fluctuation cycle repeated a plurality of times And
Have
The blood information acquisition unit
An electrocardiogram acquisition unit for acquiring an electrocardiogram signal of the subject;
The subject information acquisition unit includes:
Based on the electrocardiogram signal, an R wave generation timing and a T wave generation timing of the electrocardiogram signal are determined ,
A period from the start timing determined based on the R wave generation timing of the electrocardiogram signal to the elapse of a first time from the R wave generation timing of the electrocardiogram signal to the T wave generation timing of the electrocardiogram signal Without using a signal corresponding to the photoacoustic wave generated outside the period from the start timing until the first time elapses, using at least part of the signal corresponding to the photoacoustic wave generated in obtaining the object information, the photoacoustic apparatus it said. A light irradiation unit that irradiates the subject with pulsed light multiple times;
Receiving a photoacoustic wave generated by irradiating the subject with pulsed light from the light irradiation unit, and outputting a plurality of signals corresponding to a plurality of times of light irradiation; and
A blood information acquisition unit for acquiring information on the blood volume of the subject;
Subject information acquisition for acquiring subject information in a region of interest in the subject based on the plurality of signals acquired in a common period within each fluctuation cycle of the blood volume fluctuation cycle repeated a plurality of times And
Have
The blood information acquisition unit
An electrocardiogram acquisition unit for acquiring an electrocardiogram signal of the subject;
The subject information acquisition unit includes:
At least a signal corresponding to a photoacoustic wave generated during a period from a start timing determined based on an R wave generation timing of the electrocardiogram signal to a time of not less than 0.3 seconds and not more than 0.45 seconds. that use some acquires the object information, the photoacoustic apparatus you said. A light irradiation unit that irradiates the subject with pulsed light multiple times;
Receiving a photoacoustic wave generated by irradiating the subject with pulsed light from the light irradiation unit, and outputting a plurality of signals corresponding to a plurality of times of light irradiation; and
A blood information acquisition unit for acquiring information on the blood volume of the subject;
Subject information acquisition for acquiring subject information in a region of interest in the subject based on the plurality of signals acquired in a common period within each fluctuation cycle of the blood volume fluctuation cycle repeated a plurality of times And
An input unit configured to be able to input the type of part of the region of interest;
Possess the type of portion of the region of interest, a storage unit relation table with the second time until the generation timing or RaHiraku start timing of the R-wave is stored, and
The blood information acquisition unit
An electrocardiogram acquisition unit for acquiring an electrocardiogram signal of the subject;
The subject information acquisition unit includes:
The second time corresponding to the type of region of the region of interest input by the input unit is read from the relationship table,
Based on the generation timing of the R wave of the electrocardiogram signal and the second time read from the relation table, the start timing is set ,
At least a part of the signal corresponding to the photoacoustic wave generated in the period from the start timing to the first time from the generation timing of the R wave of the electrocardiogram signal to the generation timing of the T wave of the electrocardiogram signal using, without using the signal corresponding to the photoacoustic wave generated in the other period to the from the start timing of the first time has elapsed, to obtain the object information, you characterized light acoustic device. The subject information acquisition unit sets the start timing based on an R wave generation timing of the electrocardiogram signal, information on a distance between the heart of the subject and the region of interest, and information on blood flow velocity. The photoacoustic apparatus according to any one of claims 4 to 6 . A light irradiation unit that irradiates the subject with pulsed light multiple times;
Receiving a photoacoustic wave generated by irradiating the subject with pulsed light from the light irradiation unit, and outputting a plurality of signals corresponding to a plurality of times of light irradiation; and
A blood information acquisition unit for acquiring information on the blood volume of the subject;
Subject information acquisition for acquiring subject information in a region of interest in the subject based on the plurality of signals acquired in a common period within each fluctuation cycle of the blood volume fluctuation cycle repeated a plurality of times And
Have
The blood information acquisition unit
An electrocardiogram acquisition unit for acquiring an electrocardiogram signal of the subject;
The subject information acquisition unit includes:
A period from the start timing determined based on the R wave generation timing of the electrocardiogram signal to the elapse of a first time from the R wave generation timing of the electrocardiogram signal to the T wave generation timing of the electrocardiogram signal Without using a signal corresponding to the photoacoustic wave generated outside the period from the start timing until the first time elapses, using at least part of the signal corresponding to the photoacoustic wave generated in Obtaining the subject information;
The light irradiation unit, a plurality of times pulsed light at a constant repetition frequency, to irradiate the subject, photoacoustic devices it said. The light irradiation unit has a light source capable of emitting each pulsed light of a plurality of different wavelengths,
The light source, in addition to the period from the start time to the lapse of the first period, the photoacoustic device according to any one of claims 1 to 8, characterized in that, for switching the plurality of wavelengths . A light irradiation unit that irradiates the subject with pulsed light multiple times;
Receiving a photoacoustic wave generated by irradiating the subject with pulsed light from the light irradiation unit, and outputting a plurality of signals corresponding to a plurality of times of light irradiation; and
A blood information acquisition unit for acquiring information on the blood volume of the subject;
Subject information acquisition for acquiring subject information in a region of interest in the subject based on the plurality of signals acquired in a common period within each fluctuation cycle of the blood volume fluctuation cycle repeated a plurality of times And
Have a storage unit for storing the plurality of signals,
The blood information acquisition unit
An electrocardiogram acquisition unit for acquiring an electrocardiogram signal of the subject;
The subject information acquisition unit includes:
A period from the start timing determined based on the R wave generation timing of the electrocardiogram signal to the elapse of a first time from the R wave generation timing of the electrocardiogram signal to the T wave generation timing of the electrocardiogram signal Without using a signal corresponding to the photoacoustic wave generated outside the period from the start timing until the first time elapses, using at least part of the signal corresponding to the photoacoustic wave generated in Obtaining the subject information;
Extracted from the plurality of signals stored in the storage unit by extracting at least a part of a signal corresponding to a photoacoustic wave generated during the period from the start timing until the first time elapses. signal to acquire the object information on the basis of the photoacoustic apparatus you said.

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