JP2020036981A - Subject information acquisition device and control method thereof - Google Patents

Abstract

To provide information related to an error of characteristic information due to a position deviation of a subject concerning photoacoustic imaging.SOLUTION: A subject information acquisition device includes: a light source to generate light of a first wavelength and a second wavelength; a conversion element for receiving an acoustic wave to be generated by irradiating a subject with light of the first and second wavelengths and outputting first and second reception signals; a characteristic information acquisition section for acquiring first and second characteristic information distributions on the basis of the first and second reception signals and acquiring a material concentration distribution inside a subject on the basis of the first and second characteristic information distributions; a position deviation amount acquisition section for acquiring a position deviation amount between the first and second characteristic information distributions; and a display control section for outputting an image based on a material concentration distribution and a position deviation amount to a display section.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a subject information acquisition device and a control method thereof.

  As one of imaging techniques using light, there is photoacoustic imaging (PAI). In photoacoustic imaging, first, a subject is irradiated with pulsed light generated from a light source. After the irradiation light propagates and diffuses in the subject, when the light absorber in the subject absorbs the energy of the light, an acoustic wave (hereinafter, referred to as a photoacoustic wave) is generated. The photoacoustic wave is received by the ultrasonic probe (transducer), and the received signal is analyzed and processed in the processing device, so that information on the optical characteristic value inside the subject is obtained as image data. Thereby, the optical characteristic value distribution in the subject is visualized.

  In recent years, in order to obtain information on fine light absorbers, improvement in resolution of photoacoustic imaging has been required. Therefore, development of a photoacoustic microscope that focuses sound or collects irradiation light to image an absorber such as a micro blood vessel near the surface of a subject with high resolution has been advanced. In Patent Literature 1, resolution is improved by condensing irradiation light with a lens and arranging a subject at a focal position of light.

  Further, the light absorber inside the subject has different absorption characteristics depending on the wavelength. Therefore, by irradiating the subject with light having different wavelengths from each other and performing a calculation based on the signal intensity of the photoacoustic wave for each wavelength, it is possible to obtain a distribution regarding the substance concentration in the subject. Specifically, the distribution relating to the concentration of the substance is imaged using the absorption coefficient value of the light in the subject obtained for each wavelength and the wavelength dependence of the light absorption specific to the target substance. Furthermore, the oxygen saturation of blood can be acquired based on the concentration of oxyhemoglobin HbO and the concentration of deoxyhemoglobin Hb.

JP 2011-519281 A

  When the subject is a living body, the subject may move during the photoacoustic measurement due to pulsation, respiration, or other body movements. As a result, the relative positional relationship between the subject, the ultrasonic probe, and the light irradiation unit is shifted. In the case of a hand-held photoacoustic device in which the operator holds the probe, or in the case of a photoacoustic device in which the ultrasonic probe is moved (scanned) to image a wide area, the subject does not move. However, if the ultrasonic probe moves from an ideal position, the above-described relative positional relationship shifts. Further, due to the deformation of the subject due to the body movement, the positional relationship of each part inside the subject may change.

  During the measurement of oxygen saturation, etc., between the measurement at the first wavelength and the measurement at the second wavelength, if the above-mentioned body movement or the movement of the ultrasonic probe occurs, the photoacoustic derived from each wavelength A shift or deformation occurs between the images. In the future, such shifts and deformations will be collectively referred to as “position shifts”. When such a displacement between wavelengths occurs, the light absorbers at different positions in the subject are compared when calculating the substance concentration. As a result, the accuracy of the density calculation may be reduced.

In particular, when the light absorber of interest is blood, if the positional relationship shifts between the measurement wavelengths, the position of the blood vessel at each wavelength shifts. As a result, the ratio of the absorption coefficient between wavelengths at each blood vessel position becomes an erroneous value, so that an erroneous oxygen saturation is obtained.

  Note that the positional deviation in this specification means that the position of the subject, the position of the ultrasonic probe, and the relative positional relationship between the two are deviated from the design values of the apparatus and the set values at the time of scanning. I do. For example, when scanning an ultrasonic probe, the photoacoustic wave is detected at each position on the scanning trajectory, so that the measurement position changes each time it is detected. However, since such a position change is known information, it can be reflected in image reconstruction, and is not called a position shift.

  In a conventional photoacoustic apparatus, an operator cannot obtain information on an error in characteristic information such as oxygen saturation due to a position shift. If the operator interprets the obtained photoacoustic image without information on the reliability of the quantitative value of the characteristic information such as the oxygen saturation, the accuracy of diagnosis may be reduced.

  The present invention has been made in view of such a problem. An object of the present invention is to provide information on an error in characteristic information due to a position shift of a subject in photoacoustic imaging.

The present invention employs the following configuration. That is,
A light source that generates light of the first wavelength and light of the second wavelength,
The first wavelength light receives the acoustic wave generated by irradiating the subject, outputs a first reception signal, and generates the acoustic wave generated by irradiating the subject with the second wavelength light. A conversion element that receives and outputs a second reception signal;
Obtaining a first characteristic information distribution based on the first received signal, obtaining a second characteristic information distribution based on the second received signal, based on the first and second characteristic information distribution Characteristic information acquisition unit that acquires the substance concentration distribution inside the subject,
A displacement amount acquisition unit that acquires a displacement amount between the first characteristic information distribution and the second characteristic information distribution,
A display control unit that outputs an image based on the substance concentration distribution and the displacement amount to a display unit,
An object information acquiring apparatus, comprising:

The present invention also employs the following configuration. That is,
A light source, a conversion element, a characteristic information acquisition unit, a position shift amount acquisition unit, and a display control unit, a control method of the subject information acquisition device including:
The light source generates light of a first wavelength and light of a second wavelength,
The conversion element receives the acoustic wave generated by irradiating the subject with the light of the first wavelength and outputs a first reception signal, and the subject is irradiated with the light of the second wavelength. Receiving the generated acoustic wave and outputting a second received signal;
The characteristic information acquisition unit acquires a first characteristic information distribution based on the first received signal, acquires a second characteristic information distribution based on the second received signal, the first and second Obtaining a substance concentration distribution inside the subject based on the second characteristic information distribution,
The position shift amount obtaining unit obtains a position shift amount between the first characteristic information distribution and the second characteristic information distribution,
The display control unit outputs an image based on the substance concentration distribution and the displacement amount to a display unit,
And a control method of the subject information acquiring apparatus.

ADVANTAGE OF THE INVENTION According to this invention, in photoacoustic imaging, the information regarding the error of the characteristic information resulting from the displacement of a test object can be provided.

FIG. 2 is a schematic diagram illustrating the overall configuration of the photoacoustic apparatus according to the first embodiment. 5 is a flowchart illustrating an example of a subject information acquisition flow according to the first embodiment. 11 is a flowchart illustrating another example of the subject information acquisition flow according to the first embodiment. 11 is a flowchart illustrating an example of a subject information acquisition flow according to the second embodiment. 11 is a flowchart illustrating an example of a subject information acquisition flow according to the third embodiment. FIG. 2 is a schematic diagram illustrating an example of a display method according to the first embodiment. Schematic diagram showing an example of a display method according to the second embodiment. 14 is a flowchart illustrating an example of a subject information acquisition flow according to the fourth embodiment.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. However, dimensions, materials, shapes, relative arrangements, and the like of the components described below should be appropriately changed depending on the configuration of the apparatus to which the invention is applied and various conditions. Therefore, it is not intended to limit the scope of the present invention to the following description. In addition, the same components are denoted by the same reference numerals in principle, and description thereof is omitted.

  The present invention relates to a technique for detecting an acoustic wave propagating from a subject and generating characteristic information inside the subject. Therefore, the present invention can be regarded as a subject information acquisition device or a control method thereof, or a subject information acquisition method or a signal processing method. The present invention can also be regarded as a program for causing an information processing apparatus having hardware resources such as a CPU and a memory to execute these methods, and a storage medium storing the program.

  The subject information acquiring apparatus of the present invention includes a device that receives an acoustic wave generated by a photoacoustic effect in a subject irradiated with light (electromagnetic waves) and acquires subject information as image data. Such a device can also be called a photoacoustic device, a photoacoustic imaging device, or the like. The characteristic information is characteristic information generated using a reception signal obtained by receiving a photoacoustic wave and corresponding to each of a plurality of positions in the subject.

  The characteristic information acquired by the present invention reflects the amount of light energy absorbed and the rate of absorption. For example, information on the source of the acoustic wave generated by light irradiation, the initial sound pressure (generated sound pressure) in the subject, or the light energy absorption density and absorption coefficient derived from the initial sound pressure, and the concentration of the substance constituting the tissue Is included. The information on the concentration of the substance is, for example, oxyhemoglobin or deoxyhemoglobin concentration, total hemoglobin concentration or oxygen saturation derived therefrom. Further, glucose concentration, collagen concentration, melanin concentration, volume fraction of fat and water, and the like may be used. Further, a two-dimensional or three-dimensional object information distribution can be obtained based on the characteristic information of each position in the object. The distribution data can be generated as image data to be displayed on a display device.

  The acoustic wave referred to in the present invention is typically an ultrasonic wave, and includes an elastic wave called a sound wave and an acoustic wave. An electric signal converted from an acoustic wave by a probe or the like is also called an acoustic signal. However, the description of an ultrasonic wave or an acoustic wave in this specification is not intended to limit the wavelength of those elastic waves. The acoustic wave generated by the photoacoustic effect is called a photoacoustic wave or a photoacoustic wave. An electric signal derived from a photoacoustic wave is also called a photoacoustic signal.

  The subject information acquiring apparatus of the present invention can measure a living body such as a human or an animal, a sample other than a living body, and a calibration sample such as a phantom. When the subject is a living body, it can be expected to be used for diagnosis of vascular diseases and malignant tumors.

<First embodiment>
(Characteristic value image and misalignment distribution are displayed side by side)
Hereinafter, the configuration and processing of the subject information acquiring apparatus (photoacoustic apparatus) according to the first embodiment will be described.

((Device configuration))
FIG. 1 is a schematic diagram showing the configuration of the photoacoustic apparatus of the present embodiment. The apparatus includes a light source 100, a probe 200, an optical waveguide unit 300, a light irradiation unit 400, a scanning mechanism 500, a control unit 600, a processing unit 700, a display unit 800, and a water tank 900 as basic components. The processing unit 700 includes a signal collection unit 710, a characteristic information acquisition unit 720, and a position shift amount acquisition unit 730. The probe 200 includes a conversion element 210.

  The pulse light emitted from the light source 100 passes through the optical waveguide unit 300 and is irradiated from the light irradiation unit 400 as irradiation light 1000 to the subject 1100, and reaches the light absorber 1110 in the subject 1100. The light absorber 1110 typically includes hemoglobin in a living body, a blood vessel containing a large amount of hemoglobin, and a tumor involving new blood vessels. The light absorber 1110 absorbs light energy and generates photoacoustic waves. The generated photoacoustic wave propagates inside the subject and reaches the conversion element 210.

  The conversion element 210 outputs a time-series reception signal by receiving the photoacoustic wave. The received signals output from the conversion element 210 are sequentially input to the processing unit 700. In the present embodiment, the conversion element 210 (receiving surface) of the probe 200 is immersed in water 910 as an acoustic matching material in the water tank 900. Thus, acoustic matching between the subject 1100 and the conversion element 210 is achieved.

  The scanning mechanism 500 moves the measuring unit 1200 including the probe 200, the light irradiation unit 400, and the like to change the relative positional relationship with respect to the subject 1100. The control unit 600 controls each component block in the photoacoustic apparatus.

  The processing section 700 uses the signal input from the conversion element 210 to generate characteristic information related to the light absorption rate. Further, the processing unit 700 calculates the characteristic information on the concentration such as the oxygen saturation and the amount of displacement of the subject between the measurement wavelengths based on the characteristic information on the light absorptance obtained for each measurement wavelength. calculate. The processing unit 700 transmits the data of the generated characteristic information and the positional deviation amount to the display control unit 850. The display control unit 850 causes the display unit 800 to display the image of the characteristic information and the information on the positional shift.

Hereinafter, details of each constituent block of the photoacoustic apparatus according to the present embodiment will be described.
(Light source 100)
The light source 100 is preferably a pulse light source that can generate pulse light on the order of nanoseconds to microseconds. A specific pulse width is preferably about 1 to 100 nanoseconds. Further, the wavelength is preferably about 400 nm to 1600 nm. In particular, when imaging a blood vessel near the surface of a living body with high resolution, 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, a wavelength (700 nm or more and 1100 nm or less) where absorption is small in a background tissue of the living body is preferable. However, it is also possible to use a terahertz wave, a microwave, and a radio wave region.

As a specific light source 100, a laser is preferable. Further, in order to output light of a plurality of wavelengths including at least the first wavelength and the second wavelength, a wavelength tunable laser capable of changing the oscillating wavelength is more preferable. As the laser, a solid laser, a gas laser, a dye laser, a semiconductor laser, or the like can be used. Particularly, a pulse laser such as an Nd: YAG laser or an Alexandrite laser is preferable. Alternatively, a Ti: sa laser using Nd: YAG laser light as excitation light, an OPO (Optical Parametric Oscillators) laser, or a dye laser may be used. A plurality of light sources having different wavelengths may be used. In addition, a light emitting diode or a flash lamp can be used instead of the laser.

(Probe 200)
The probe 200 includes one or more conversion elements 210 and a housing that supports the conversion elements 210. As the conversion element 210, an element that receives an acoustic wave and converts it into an electric signal can be used. For example, a piezoelectric element using a piezoelectric phenomenon such as lead zirconate titanate (PZT), a conversion element using light resonance, and a capacitance conversion element such as a CMUT can be used.

  When the photoacoustic apparatus is a photoacoustic tomography apparatus, the probe 200 preferably includes a plurality of conversion elements 210. The plurality of conversion elements 210 are arranged so as to be arranged in a plane called a 1D array, a 1.5D array, a 1.75D array, a 2D array, or a curved surface such as an arc shape or a bowl shape. Is preferred. On the other hand, when the photoacoustic apparatus is a photoacoustic microscope, it is preferable that the probe 200 be a focus type probe. In that case, an acoustic lens is provided on the receiving surface of the conversion element 210.

  Further, in order to stabilize the shape of the subject, it is preferable to provide a holding member (not shown). In the case of a bowl-shaped probe, a dish-shaped or cup-shaped holding member is suitable. Further, a configuration in which the subject is sandwiched between two plate-like members may be adopted. The holding member is preferably made of a material that transmits light and acoustic waves. The use of the holding member also has an advantage that the calculation of the light amount distribution described later can be simplified.

  The scanning mechanism 500 mechanically moves the probe 200 with respect to the subject 1100, so that a wide range of subject information can be acquired. It is preferable that the light irradiation unit 400 and the probe 200 move in synchronization. As a scanning method, a raster scan, a snake scan, a spiral scan, or the like can be used according to the shape of the probe or the subject. When the probe 200 is a handheld type, the probe 200 has a grip portion for the operator to grip the probe 200.

(Optical waveguide 300)
The optical waveguide 300 transmits light from the light source 100 to the light irradiator 400. The optical waveguide 300 can use an optical element such as an optical fiber, a lens, a mirror, a prism, and a diffusion plate.

(Light irradiation unit 400)
The light irradiator 400 irradiates the subject 1100 with the light transmitted by the optical waveguide 300 as irradiation light 1000. Here, in the photoacoustic tomography apparatus, it is preferable that the light irradiating section 400 irradiates the light beam with the diameter of the light beam expanded by a lens or the like. On the other hand, in the photoacoustic microscope, in order to increase the resolution, it is preferable that the light irradiating portion of the optical waveguide 300 is formed of a lens or the like, and that the irradiation is performed while focusing the diameter of the irradiation light 1000.

  Further, the light irradiation unit 400 may be moved with respect to the subject 1100. Further, the light irradiation unit 400 may be moved in conjunction with the probe 200. Thereby, a wide range can be imaged. In the case of a bowl-shaped probe, the light irradiation section 400 may be arranged at the center of the bowl. It is also possible to directly irradiate the subject 1100 with light from the light source 100 without using the optical waveguide unit 300 and the light irradiation unit 400.

(Processing unit 700)
The processing unit 700 according to the present embodiment includes a signal collection unit 710, a characteristic information acquisition unit 720, and a displacement amount calculation unit 730.

  The signal collection unit 710 collects a time-series analog reception signal (referred to as a photoacoustic signal) output from the conversion element 210. Then, signal processing such as amplification of the received signal, AD conversion of the analog received signal, and storage of the digitized received signal are performed. In addition, the signal collection unit 710 collects, for each irradiated pulse, a signal related to the light amount (referred to as a light amount signal) output from a photodetector (not shown) on which a part of the irradiation light 1000 is incident. As the signal collecting unit 710, a circuit called DAS (Data Acquisition System) can be used. For example, the signal collection unit 710 includes an amplifier that amplifies a received signal, an AD converter, and the like. Note that the amplifier may be provided in the probe 200. In the present invention, light of the first wavelength is converted to a first received signal, and light of the second wavelength is converted to a second received signal.

  The characteristic information acquisition unit 720 acquires characteristic information related to the light absorption rate in the subject for each position using the photoacoustic signal and the light amount signal collected by the signal collection unit 710. For example, a generated sound pressure distribution, a light energy absorption density distribution, a light absorption coefficient distribution, and the like are acquired. Further, the characteristic information acquisition unit 720 obtains characteristic information (particularly, oxygen saturation distribution of blood) relating to the concentration of a substance present in the subject, using characteristic information relating to the absorptance of light of each wavelength. As an image reconstruction method at the time of acquiring the characteristic information, a known method such as UBP (Universal Back Projection), FBP (Filtered Back Projection), and phasing addition (Delay and Sum) can be used. In the present invention, a first characteristic information distribution is obtained from a first received signal, and a second characteristic information distribution is obtained from a second received signal. Further, a substance concentration distribution is obtained from the first characteristic information distribution and the second characteristic information distribution. For obtaining the substance concentration distribution, the distribution of the displacement amount may be used.

  The position shift amount calculation unit 730 calculates the position shift amount between the measurement wavelengths by using the characteristic information on the light absorptance for each measurement wavelength calculated by the characteristic information acquisition unit 720.

  An arithmetic circuit such as a processor such as a CPU or a GPU or an FPGA (Field Programmable Gate Array) chip can be used as the characteristic information acquisition unit 720 and the displacement amount calculation unit 730. It should be noted that not only one processor or arithmetic circuit but also a plurality of processors or arithmetic circuits may be used. Further, a memory for storing received signals, generated distribution data, display image data, various measurement parameters, and the like may be provided. The memory is typically composed of one or more storage media such as ROM, RAM, and hard disk.

(Display unit 800)
The display unit 800 displays the characteristic information on the concentration of the substance such as the oxygen saturation calculated by the characteristic information acquisition unit 720 and the distribution of the displacement between the measurement wavelengths calculated by the displacement calculation unit 730. As the display unit 800, an LCD (Liquid Crystal)
(Display, CRT (Cathode Ray Tube), organic EL display, etc.). The display unit 800 may be provided separately from the photoacoustic device. As the display control unit 850, an information processing device, a control circuit, or the like can be used. Alternatively, a control circuit built in the display unit may be used.

(Water tank 900)
The water tank 900 is a vessel that can hold water 910 as an acoustic matching material. By immersing the conversion element 210 provided in the probe 200 in the water 910, the subject 1100 and the conversion element 210 can be acoustically matched. Further, the surface of the water tank 900 in contact with the subject 1100 is preferably formed of a film thinner than the wavelength of the photoacoustic wave so that the photoacoustic wave can easily pass therethrough. Further, it is preferable that the acoustic matching material and the contact surface are made of a material that hardly absorbs the irradiation light 1000. As the acoustic matching material, water, ultrasonic gel, oil, or the like is preferable. Further, as the material of the contact surface, polyethylene, urethane rubber, PET or the like can be adopted. Further, an acoustic matching material such as an ultrasonic gel or water may be provided between the subject 1100 and the contact surface.

(Scanning mechanism 500)
As the scanning mechanism 500, an automatic stage using a stepping motor or a servomotor can be used. Further, it can be configured by combining mechanical parts such as an XY stage, a shaft, and a screw mechanism, and a position detection mechanism and a position control mechanism of a probe and a light irradiation unit. FIG. 1 shows a configuration in which the scanning mechanism 500 scans the measurement point on the subject 1100 by moving the measurement unit 1200. However, any configuration may be used as long as the measurement can be performed while scanning the measurement points on the subject 1100. For example, the irradiation light 1000 may irradiate the subject 1100 in a wide range, and the scanning mechanism 500 may move only the probe 200.

  Conversely, the probe 200 uses a device capable of receiving a wide range of photoacoustic waves (for example, a single transducer or an array-type transducer having a wide focus range), and the scanning mechanism 500 moves only the light irradiation unit. A configuration may be used. In this case, the irradiation light 1000 is preferably collected. When fixing the probe 200, the acoustic matching material does not need to be a liquid. For example, instead of the water tank 900 and the water 910, a gel member (such as a polyurethane-based gel) can be used.

  Further, the scanning mechanism 500 can perform scanning while changing the angles of the probe 210 and the light irradiation unit 400. Further, the scanning mechanism 500 can scan a measurement point on the subject 1100 without directly scanning the probe 200 and the light irradiation unit 400. For example, by controlling (changing or moving the angle of) the mirror that reflects the photoacoustic wave and the irradiation light 1000, the irradiation position of the irradiation light 1000 and the detection position of the photoacoustic wave can be scanned. Even in this case, the object to be moved may be any one of the light irradiation position, the photoacoustic wave detection position, and both. As such a mirror, a galvanometer mirror or a MEMS mirror is preferable.

(Control unit 600)
The control unit 600 supplies necessary control signals and data to each component block. Specifically, it supplies a signal for instructing the light source 100 to emit light, a reception control signal for the conversion element 200, and a control signal for the scanning mechanism 500. Further, it performs signal amplification control of the processing unit 600, AD conversion timing control, storage control of a received signal, and the like. As with the processing unit 700, the control unit 600 can also be configured by combining one or more circuits such as a processor such as a CPU and a GPU, and an FPGA chip. Further, a memory for storing various measurement parameters and the like may be provided. The memory is typically composed of one or more storage media such as ROM, RAM, and hard disk. These can be used together with the processing unit 700.

(Subject 1100)
The subject 1100 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 a vascular disease or a malignant tumor of a human or an animal, or to monitor the progress of chemotherapy. Therefore, the subject 1100 is assumed to be a site to be diagnosed such as a living body, specifically, a breast, neck, abdomen, face, and skin of a human body or an animal. Since the body moves due to respiration, pulsation, and the like, the living body is likely to be shifted or deformed from the installation position. However, even in the case of inanimate objects, displacement and deformation can occur. In some cases, the scanning mechanism moves the subject, but this does not correspond to the displacement according to the present invention. The position shift in the present invention refers to a state where the target of the subject has moved from an assumed position when an image is reconstructed from a photoacoustic signal derived from a plurality of wavelengths.

As the light absorber 1110 inside the subject 1100, a light absorber having a relatively high light absorption coefficient inside the subject 1100 is preferable. For example, if the human body is an object to be measured, oxyhemoglobin or deoxyhemoglobin, a blood vessel containing many of them, or a malignant tumor containing many new blood vessels is a target of the light absorber 1110. In addition, melanoma and plaque of the carotid artery wall are also targeted.

(Handheld type)
Further, the present invention can be applied to a handheld photoacoustic apparatus. In that case, the member surrounded by the dotted line 1300 may be stored in one housing that can be gripped by the operator.

((Subject information acquisition method))
In the photoacoustic apparatus according to the present embodiment, an example of a flow in which the processing unit 700 collects the measurement data, calculates the characteristic information and the amount of displacement of the subject, and displays the information on the display unit 800 will be described with reference to FIG. Will be explained. Here, the oxygen saturation is taken as an example of the characteristic information relating to the concentration, but other characteristic information can be obtained in a similar flow. This flow is started when the subject is placed in the measurable area and preparation processing such as activation of the apparatus and warm-up is completed.

  In step S101, multi-wavelength photoacoustic data and light amount data are obtained. First, the light irradiator 400 irradiates the subject with light. The conversion element 210 receives a photoacoustic wave generated for each light pulse. The signal collection unit 710 collects the time-series analog reception signals output from the conversion element 210 for each channel, performs various kinds of signal processing, and stores them. Further, the signal collecting unit 710 collects a light amount signal for each pulse output from the photodetector. At this time, in order to obtain a wide-range image, the scanning mechanism 500 moves the probe 200 and the light irradiation unit 400 relative to the subject, and receives photoacoustic waves at a plurality of scanning positions.

  By performing the above processing for a plurality of wavelengths, step S101 is completed. In this flow, after acquiring photoacoustic data and light amount data at the first wavelength, measurement at the second wavelength is performed. However, the measurement at the first wavelength and the second wavelength may be performed alternately while the probe 200 is moved by the scanning mechanism 500. Even in this case, the present invention is effective because body movement can occur during measurement using a plurality of wavelengths. As for the light amount, an estimated light amount value stored in a memory in advance may be obtained instead of actually measuring the light amount. The estimated light amount value can be calculated based on the device configuration, the light source control value, the positional relationship between the subject and the light irradiation unit, the depth of the target voxel in the subject, and the like.

  In step S102, the characteristic information acquisition unit 720 calculates light absorption distribution data in the subject for each measurement wavelength by analysis using the photoacoustic signal and the light amount signal obtained in S101. That is, the characteristic information acquisition unit 720 acquires light absorption distribution data at each measurement position by correcting the generated sound pressure generated from the photoacoustic signal by image reconstruction based on the light amount signal.

  An example of the correction method will be described. First, the characteristic information acquisition unit 720 calculates the light amount of the irradiation light 1000 applied to the subject 1100 from the light amount signal. At this time, the irradiation light amount is calculated using the relationship between the light amount signal and the irradiation light amount, which is measured in advance. It is preferable to have a relation table or a relational expression between the light quantity signal and the irradiation light quantity. Then, the characteristic information acquisition unit 720 calculates light amount distribution data in the subject based on the irradiation light amount and the shape of the subject. At this time, calculation using the finite element method or the Monte Carlo method can be performed based on the light transport equation and the light diffusion equation. Further, by measuring the irradiation distribution of the irradiation light in advance, more accurate light amount distribution data can be obtained.

Thereafter, the generated sound pressure distribution data is divided by the light quantity distribution data to obtain light absorption distribution data in the subject or data proportional to the light absorption distribution data in the subject. When the measurement is performed while scanning with the photoacoustic tomography apparatus, the generated sound pressure distribution data and the light amount distribution data at each scanning position are obtained by using the photoacoustic signal and the light amount signal output from the signal collecting unit 710 at each scanning position. Is calculated. Then, based on each scanning position information, divide the total generated sound pressure distribution data obtained by adding the generated sound pressure distribution data at each scanning position by the total light amount distribution data obtained by adding the light amount distribution data at each scanning position. Thereby, light absorption distribution data in the subject can be obtained.

  On the other hand, when the photoacoustic apparatus is a photoacoustic microscope, the characteristic information acquisition unit 720 performs envelope detection on the photoacoustic signal output from the photoacoustic signal collection unit 710 with respect to time change. Subsequently, the time axis direction of the signal for each light pulse is converted to the depth direction and plotted on the space coordinates. This is performed for each measurement position (scanning position) to obtain sound pressure distribution data.

  Further, the characteristic information acquisition unit 720 corrects sound pressure distribution data at each measurement position using the light amount signal output from the signal collection unit 710, and acquires light absorption distribution data in the subject. For example, when the photodetector is a photodiode, the peak value of the received signal output from the photodiode is taken at each measurement point. Then, by dividing the sound pressure distribution data by the peak value, light absorption distribution data in the subject or data proportional thereto is obtained.

  In the step of S103, the characteristic information acquisition unit 720 obtains the oxygen saturation distribution (substance concentration distribution) of blood using the light absorption distribution data of each wavelength obtained in S102.

  On the other hand, in the step of S104, the displacement amount calculating section 730 calculates the displacement amount between the measurement wavelengths using the light absorption distribution data for each measurement wavelength obtained in S102. Hereinafter, an example of the method of calculating the displacement will be described. One of the two wavelength light absorption distribution data obtained in S102 is set as a reference image. Then, the light absorption distribution of the other wavelength (called a deformed image) is deformed and aligned so as to match the reference image. Specifically, the correlation between the images is calculated at a point randomly extracted from the volume data of the light absorption distribution. Then, the image is deformed and optimized so that the correlation becomes high. At this time, an index such as a normalized cross-correlation indicating the degree of coincidence between the reference image and the deformed image can be used.

  A known method such as FreeFormDeformation can be used for the deformation. Note that the deformation position may be adjusted in multiple stages. For example, after the rotation, enlargement, reduction, shearing, and translation are performed by Affine transformation to roughly align the positions, FreeFormDeformation is used. In the present embodiment, the light absorption distribution is used as it is for the position shift correction, but an unnecessary portion may be removed, and further, a preprocessing such as a logarithmic image of the light absorption distribution may be performed.

  In the deformed image subjected to the deformed position adjustment in this way, the amount by which each point in the volume data has moved before and after the deformed position adjustment is defined as a position shift amount. As the displacement amount, a linear movement distance of each point before and after the deformation, a movement amount in a specific direction (for example, a direction perpendicular to the receiving surface of the conversion element 210), a vector amount having each direction component, and the like can be used. . In the measurement of three or more wavelengths, similar deformation alignment can be performed using the light absorption distribution at a certain measurement wavelength as a reference image.

  In step S105, the display unit 800 displays the oxygen saturation distribution calculated in S103 and the positional deviation amount distribution between the measurement wavelengths calculated in S104. The display method of both images may be superimposed display, alternate display, annotated display using characters or symbols, or the like, in addition to the side-by-side display as shown in FIG. Further, the display method may be changed in accordance with an operator's instruction using an input device such as a mouse or a keyboard.

As a method of displaying the displacement amount distribution, there is a method of directly displaying the displacement amount as shown in FIG. In the direct display method, it is preferable that the amount of misalignment corresponds to brightness, saturation, hue, and the like. All of these display methods may be used. Further, as shown in FIG. 6A, a certain threshold value is provided for the displacement amount, and binarized together with the characteristic information (810) according to whether the displacement amount is greater than or less than the threshold value. It may be displayed (820). Further, as shown in FIG. 6B, based on the obtained positional deviation amount, an error (820) of the characteristic information relating to the density caused by the positional deviation is calculated and displayed together with the characteristic information (810). good.

  In the case of a photoacoustic microscope, it is preferable to display the positional deviation amount distribution in the depth direction (the direction perpendicular to the receiving surface of the conversion element 210). This is because the shift of the focus position of the ultrasonic wave due to the position shift in the depth direction greatly changes the received sound pressure, and consequently increases the error of the characteristic information.

  After the processing by the photoacoustic apparatus up to step S105 is completed, the operator performs image interpretation based on the characteristic information related to the concentration of the substance such as the oxygen saturation and the positional deviation amount distribution between the measurement wavelengths displayed in S105. At this time, it is preferable to interpret the oxygen saturation distribution image using the displacement amount as an index of reliability.

<Modification>
In the present embodiment, the amount of displacement between the measurement wavelengths is calculated using the light absorption distribution data for each measurement wavelength in S104. However, other characteristic information may be used. For example, FIG. 3 shows a flow when the displacement amount calculating unit 730 calculates the displacement amount using the generated sound pressure distribution data.

  In S202, the characteristic information acquisition unit 720 calculates generated sound pressure distribution data. In S205, the displacement amount calculation unit 730 calculates the displacement amount using the generated sound pressure distribution data. The method of calculating the amount of displacement is the same as when using the light absorption distribution data. On the other hand, in S203 to S204, an oxygen saturation distribution (substance concentration distribution) is obtained based on a light absorption distribution derived from light of a plurality of wavelengths. Other steps are the same as those in FIG.

  Further, without using the characteristic information on the light absorption rate, for example, the subject 1100 may be photographed by a camera or the like at the time of measurement at each wavelength, and the displacement of the subject between the measurement wavelengths may be calculated based on the camera image. .

  As described above, according to the present embodiment, it is possible to provide information on an error in the characteristic information caused by the displacement of the subject. In particular, since information relating to the reliability of the characteristic information due to the positional deviation can be displayed in comparison with the reconstructed image, it is useful for interpretation by the operator.

<Embodiment 2>
(Characteristic value image and misalignment distribution are superimposed and displayed)
The configuration of the photoacoustic device of the present embodiment is the same as that of the first embodiment. Hereinafter, the processing contents of the present embodiment will be described with reference to the flow of FIG. Steps S301 to S304 are the same as steps S101 to S104 in the first embodiment.

  In step S305, the characteristic information acquisition unit 720 reflects the positional deviation amount distribution using the substance concentration distribution of the oxygen saturation distribution obtained in step S303 and the positional deviation amount distribution between the measurement wavelengths obtained in step S304. Then, the characteristic information on the concentration of the substance is created.

For example, a certain threshold value is provided for the displacement amount, and the characteristic information relating to the concentration of the substance is set to 0 or null (no information) for a portion where the displacement amount is equal to or larger than the threshold value. As a result, in the next step S306, the characteristic information relating to the concentration of the substance is not displayed for a portion where the displacement is large and the characteristic information has a large error. Therefore, only the characteristic information at the position where the error is small and the reliability is high is displayed. It is preferable that the threshold value of the displacement amount is set according to the resolution of the photoacoustic apparatus. For example, in the case of a photoacoustic microscope having a resolution of 50 μm, the threshold is preferably set to 50 μm.

  As another example, there is a method of weighting characteristic information on the concentration of a substance in accordance with a positional deviation amount distribution. For example, the characteristic information relating to the concentration of the substance is assigned as hue data, and the displacement amount is assigned as lightness data. At this time, the brightness data is created such that the lightness is higher as the displacement amount is smaller, and the brightness is lower as the displacement amount is larger. As a result, in the next step S306, a portion having a small displacement amount, that is, a portion having a small value error and a high reliability is emphasized.

  In the case of a photoacoustic microscope, it is preferable to create characteristic information on the concentration of a substance reflecting the positional deviation amount distribution using a positional deviation amount distribution in the depth direction (perpendicular to the receiving surface of the conversion element 210). .

  In the step of S306, the characteristic information reflecting the positional deviation amount distribution created in S305 is displayed on the display unit 800. For example, in FIG. 7A, the characteristic information is displayed only for a portion where the displacement amount is equal to or less than a predetermined threshold. In FIG. 7B, the brightness is adjusted according to the amount of displacement, and characteristic information data relating to density is displayed as hue data.

  As described above, according to the present embodiment, information regarding an error in a quantitative value of characteristic information such as oxygen saturation due to a position shift is given to an operator. In particular, in the present embodiment, the index of the reliability of the image is superimposed on the reconstructed image inside the subject, and the reliability of each part can be understood in a list.

<Embodiment 3>
(Calculate the oxygen saturation after correcting the displacement)
The configuration of the photoacoustic device of the present embodiment is the same as in each of the above embodiments. Hereinafter, the processing contents of the present embodiment will be described with reference to the flow of FIG. 5 focusing on parts different from the above embodiments. Steps S401 to S402 are the same as steps S101 to S102 of the first embodiment.

  In the step of S403, the characteristic information acquisition unit 720 performs deformation and alignment with respect to the positional deviation of the light absorption distribution data for each measurement wavelength obtained in S402. From now on, the deformation and alignment between the measurement wavelengths will be referred to as position shift correction. When detecting the position shift in the position shift correction, the method of the deformed position alignment described in the first embodiment can be used. The characteristic information acquisition unit 720 corrects the positions of the pixels of the image that is not the reference image based on the detected positional shift amount.

  In step S404, the characteristic information acquisition unit 720 uses the light absorption distribution data of each wavelength after the position shift correction obtained in S403 to obtain a substance concentration distribution such as a blood oxygen saturation distribution.

  In step S405, the displacement amount calculating unit 730 calculates the displacement amount between the measurement wavelengths using the light absorption distribution data for each measurement wavelength obtained in S402. The method of calculating the amount of displacement is the same as that in step S104 of the first embodiment. In the present embodiment, since the positional deviation between the measurement wavelengths is corrected in S403, the positional deviation amount distribution may be obtained by comparing the data before the positional deviation correction and the data after the positional deviation correction.

  In step S406, a substance concentration distribution such as an oxygen saturation distribution is displayed on the display unit 800. In this embodiment, since the positional deviation has been corrected, only the oxygen saturation distribution may be displayed to simplify the display. However, the positional deviation amount distribution may be displayed for reference. The display method of both images may be any of the above-described methods such as juxtaposition, superimposition display, and alternate display. Each display method may be switched by a user operation. The alternate display may be performed by automatically switching between the two images to be displayed, or may be configured to switch the displayed image by a user operation. Further, as in the second embodiment, the positional deviation amount and the oxygen saturation (characteristic information value) may be displayed by reflecting the color and the like.

  After the processing by the photoacoustic apparatus up to step S406 is completed, the operator interprets the oxygen saturation distribution image. At this time, since the positional shift amount has been corrected, the operator can acquire highly accurate subject internal information only by viewing the displayed images. In addition, when the positional deviation amount distribution is displayed together with the oxygen saturation distribution, the accuracy of diagnosis is further improved by using the distribution as an index of reliability. In the present embodiment, various characteristic information values and camera images may be used for calculating and correcting the amount of displacement.

  In the present embodiment, the characteristic information regarding the density is calculated after the position shift is corrected, so that the value error due to the position shift is small. This effect is remarkable in the case of photoacoustic tomography. On the other hand, in the case of a photoacoustic microscope, the ultrasonic focus position shift accompanying the position shift in the depth direction (direction of the element directional axis) is sensitively reflected on the received sound pressure and the characteristic information value. Then, when the characteristic information regarding the density is calculated after the alignment, the positional deviation can be corrected, but the value of the absolute value of the sound pressure cannot be corrected. Therefore, a value error occurs according to the positional deviation amount. For the above reasons, this embodiment is particularly suitable for a photoacoustic microscope.

  As described above, according to the photoacoustic apparatus according to the present embodiment, it is possible to provide information on an error in a quantitative value of characteristic information such as oxygen saturation due to a position shift. In particular, since the image whose positional deviation has been corrected can be presented, it is easy for the operator to see and intuitively understand.

<Embodiment 4>
Hereinafter, an example of the processing flow of the fourth embodiment will be described with reference to FIG. In this embodiment, a Ti: sa laser is used as the light source 100. The laser light is applied to the surface of the subject 1100 using an optical fiber that is the optical waveguide 300. As the probe 200, one in which 512 piezo elements, which are the conversion elements 210, are spirally arranged on a hemispherical support is used. This hemispherical support is scanned on an XY plane by a scanner (scanning mechanism 500) that moves along the X axis and the Y axis.

  In addition, the signal collector 710 of the present embodiment has a function of simultaneously receiving all data from the 512-channel acoustic wave detection element, amplifying and converting the data, and then transferring the data to the computer that is the characteristic information acquisition unit 720. . The sampling frequency of the signal collector 710 is 20 MHz, and the timing of light irradiation is the reception start timing.

  The subject 1100 is a phantom made of hemispherical urethane rubber simulating a living body. In the phantom, titanium oxide as a scatterer and two kinds of inks simulating the absorption spectrum of blood as an absorber are mixed. Further, a spherical black rubber having a diameter of 0.5 mm is embedded as a light absorber 1110 in the center of the phantom. The size of the phantom is 80 mm in diameter. The phantom is fixed with a transparent plastic cup (holding member), and is in contact with the probe 200 via water as an acoustic matching member.

In the step of S801, while scanning the hemispherical probe along a circumferential or spiral trajectory, the wavelengths of 756 nm and 797 nm are applied to the phantom by using two Ti: sa lasers.
Are alternately irradiated at 10 Hz. Then, the probe 200 acquires a photoacoustic signal at each measurement position. Further, similarly to the first embodiment, light amount data at each measurement position is obtained. Note that, depending on the accuracy of the scanning mechanism, an error of about ± 200 μm may occur with respect to the designated measurement position. Next, in step S802, the characteristic information acquisition unit 720 calculates the light absorption distribution at each measurement position for each wavelength in the same manner as in the first embodiment.

  In the step of S803, the displacement amount acquisition unit 730 calculates the displacement amount between wavelengths. Here, in the light absorption distribution calculated for each wavelength at each measurement position, the light absorption distribution measured at a wavelength of 797 nm is set as a reference image. Then, the movement amount at which the correlation value between the reference image and the light absorption distribution data at the wavelength of 756 nm becomes maximum is defined as the shift amount. As a result, the shift amounts (or shift vectors) in the X, Y, and Z directions at each measurement position are calculated.

  This description corresponds to the case of a step-and-repeat method in which the scanning mechanism 500 repeatedly stops and moves the probe, and performs photoacoustic measurement at each wavelength at each stop position. However, this embodiment can also be applied to a case where the probe is continuously moved to perform photoacoustic measurement by performing appropriate interpolation calculation.

  In step S804, the characteristic information acquisition unit 720 shifts the light absorption distribution data having the wavelength of 756 nm in the X, Y, and Z directions based on the shift amount calculated in step S803, and corrects the shift amount. Then, an oxygen saturation distribution image is calculated from the reference image and the light absorption distribution data of the wavelength 756 nm after the shift amount correction. As a result, an oxygen saturation distribution image reflecting the displacement amount distribution is created.

  In step S805, the created oxygen saturation distribution image is displayed on the display unit 800. The display method may be the same as in the above embodiments. Thereby, a high-precision oxygen saturation distribution image in which the shift amount has been corrected is displayed at the time of interpretation by the operator. Note that the positional deviation amount distribution (vector) between the measurement wavelengths calculated by the positional deviation amount calculating unit 730 may be displayed together with the oxygen saturation as information on the reliability.

  As described above, according to the present invention, it is possible to provide an operator with information on an error in a quantitative value of characteristic information such as oxygen saturation due to a displacement of a subject. The operator can perform image interpretation using these pieces of information as an index of image reliability, which leads to more accurate diagnosis.

  The present invention has been described in detail with reference to the 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.

<Other embodiments>
The present invention can also be implemented by a computer (or a device such as a CPU or an MPU) of a system or an apparatus that implements the functions of the above-described embodiments by reading and executing a program recorded in a storage device. Further, for example, the present invention can be implemented by a method including steps executed by a computer of a system or an apparatus that realizes the functions of the above-described embodiments by reading and executing a program recorded in a storage device. . For this purpose, the program is executed, for example, via a network or from various types of storage media that can be the storage device (that is, computer-readable storage media that temporarily stores data). Provided to Therefore, the computer (including a device such as a CPU and an MPU), the method, the program (including a program code and a program product), and a computer-readable recording medium for non-temporarily storing the program are all of the present invention. Included in the scope of the invention.

  100: light source, 210: conversion element, 720: characteristic information acquisition unit, 730: displacement amount acquisition unit, 800: display unit, 850: display control unit

The present invention employs the following configuration. That is,
A light source that generates light of the first wavelength and light of the second wavelength,
The first wavelength light receives the acoustic wave generated by irradiating the subject, outputs a first reception signal, and generates the acoustic wave generated by irradiating the subject with the second wavelength light. A conversion element that receives and outputs a second reception signal;
Obtaining a first characteristic information distribution based on the first received signal, obtaining a second characteristic information distribution based on the second received signal, the first characteristic information distribution and the second characteristic A characteristic information acquisition unit that acquires a substance concentration distribution inside the subject based on the information distribution,
Between irradiation of the first irradiation and the second wavelength of light having a wavelength of the light, the position to obtain the positional displacement amount distribution between the front Symbol first characteristic information distribution and said second characteristic information distribution A shift amount obtaining unit;
And an image representing the material density distribution, and a display control unit Ru is displayed on the display unit an image representing the positional displacement amount distribution,
An object information acquiring apparatus, comprising:
Further, the present invention employs the following configuration. That is,
A light source that generates light of the first wavelength and light of the second wavelength,
The first wavelength light receives the acoustic wave generated by irradiating the subject, outputs a first reception signal, and generates the acoustic wave generated by irradiating the subject with the second wavelength light. A conversion element that receives and outputs a second reception signal;
Obtaining a first characteristic information distribution based on the first received signal, obtaining a second characteristic information distribution based on the second received signal, the first characteristic information distribution and the second characteristic A characteristic information acquisition unit that acquires a substance concentration distribution inside the subject based on the information distribution,
Between the irradiation of the light of the first wavelength and the irradiation of the light of the second wavelength, a positional shift for obtaining a positional shift amount distribution between the first characteristic information distribution and the second characteristic information distribution. A quantity acquisition unit;
A display control unit that causes an image reflecting the positional deviation amount distribution to the substance concentration distribution acquired by the characteristic information acquisition unit to be displayed on a display unit,
An object information acquiring apparatus, comprising:

The present invention also employs the following configuration. That is,
A light source, a conversion element, a characteristic information acquisition unit, a position shift amount acquisition unit, and a display control unit, a control method of the subject information acquisition device including:
The light source generates light of a first wavelength and light of a second wavelength,
The conversion element receives the acoustic wave generated by irradiating the subject with the light of the first wavelength and outputs a first reception signal, and the subject is irradiated with the light of the second wavelength. Receiving the generated acoustic wave and outputting a second received signal;
The characteristic information acquiring unit acquires a first characteristic information distribution based on the first received signal, acquires a second characteristic information distribution based on the second received signal, and acquires the first characteristic. Obtaining a substance concentration distribution inside the subject based on the information distribution and the second characteristic information distribution ,
Before SL positional shift amount obtaining unit, between the irradiation of the said irradiation of the first wavelength light second wavelength light, between the second characteristic information distribution and said first characteristic information distribution Obtaining a displacement distribution ;
Wherein the display control unit, and an image representing the material density distribution, comprising the steps of Ru is displayed on the display unit and an image representing the positional displacement amount distribution,
And a control method of the subject information acquiring apparatus.
Further, the present invention employs the following configuration. That is,
A light source, a conversion element, a characteristic information acquisition unit, a position shift amount acquisition unit, and a display control unit, a control method of the subject information acquisition device including:
The light source generates light of a first wavelength and light of a second wavelength,
The conversion element receives the acoustic wave generated by irradiating the subject with the light of the first wavelength and outputs a first reception signal, and the subject is irradiated with the light of the second wavelength. Receiving the generated acoustic wave and outputting a second received signal;
The characteristic information acquiring unit acquires a first characteristic information distribution based on the first received signal, acquires a second characteristic information distribution based on the second received signal, and acquires the first characteristic. Obtaining a substance concentration distribution inside the subject based on the information distribution and the second characteristic information distribution,
The position shift amount acquisition unit, between the irradiation of the light of the first wavelength and the irradiation of the light of the second wavelength, the position between the first characteristic information distribution and the second characteristic information distribution Obtaining a shift amount distribution;
The display control unit, a step of displaying on the display unit an image reflecting the displacement amount distribution in the substance concentration distribution acquired by the characteristic information acquisition unit,
And a control method of the subject information acquiring apparatus.

Claims (17)

A light source that generates light of the first wavelength and light of the second wavelength,
The first wavelength light receives an acoustic wave generated by irradiating the subject, outputs a first reception signal, and generates the acoustic wave generated by irradiating the subject with the second wavelength light. A conversion element that receives and outputs a second reception signal;
Obtaining a first characteristic information distribution based on the first received signal, obtaining a second characteristic information distribution based on the second received signal, based on the first and second characteristic information distribution Characteristic information acquisition unit that acquires the substance concentration distribution inside the subject,
A displacement amount acquisition unit that acquires a displacement amount between the first characteristic information distribution and the second characteristic information distribution,
A display control unit that outputs an image based on the substance concentration distribution and the displacement amount to a display unit,
A subject information acquisition device, comprising: The displacement amount acquisition unit, between the irradiation of the light of the first wavelength and the irradiation of the light of the second wavelength, based on a change in the relative positional relationship between the subject and the conversion element, The subject information acquiring apparatus according to claim 1, wherein the displacement amount is acquired. The said displacement amount acquisition part acquires the said displacement amount by the body movement of the said test object between irradiation of the light of the said 1st wavelength, and irradiation of the light of a said 2nd wavelength, The Claim. Item 4. The subject information acquisition device according to item 1 or 2. The said displacement amount acquisition part acquires the said displacement amount by deformation | transformation of the said test object between the irradiation of the light of the said 1st wavelength, and the irradiation of the light of a said 2nd wavelength, The Claims characterized by the above-mentioned. 4. The subject information acquiring apparatus according to any one of 1 to 3. 5. The display control unit according to claim 1, wherein the display control unit displays an image representing the substance concentration distribution and an image representing the distribution of the displacement amount side by side on the display unit. 6. Subject information acquisition device. 5. The display control unit according to claim 1, wherein the display control unit displays an image representing the substance concentration distribution and an image representing the distribution of the displacement amount on the display unit in an overlapping manner. 6. The subject information acquisition device according to the above. 7. The display device according to claim 5, wherein the display control unit causes the display unit to display an image in which the distribution of the displacement amount corresponds to at least one of lightness, saturation, and hue. 8. Sample information acquisition device. The object information acquiring apparatus according to claim 5, wherein the displacement amount acquiring unit acquires a binarized distribution of the displacement amount. The subject information acquiring apparatus according to claim 5, wherein the displacement amount acquiring unit acquires an error in the substance concentration distribution caused by the displacement based on the distribution of the displacement amount. The subject information acquiring apparatus according to any one of claims 1 to 4, wherein the characteristic information acquiring unit acquires the substance concentration distribution corrected based on the displacement amount. The characteristic information acquisition unit is configured to modify the second characteristic information distribution in accordance with the first characteristic information distribution based on the displacement amount, and to apply the modified second characteristic information distribution to the first characteristic information distribution. The subject information acquiring apparatus according to claim 10, wherein the substance concentration distribution is acquired by using the characteristic information distribution of (1). 12. The subject information acquiring apparatus according to claim 11, wherein the display control unit causes the display unit to display only a portion of the substance concentration distribution where the displacement amount is equal to or less than a predetermined threshold. The subject information acquiring apparatus according to claim 11, wherein the display control unit causes the display unit to display the substance concentration distribution weighted based on the distribution of the displacement amount. 14. The displacement amount acquiring unit according to claim 1, wherein the displacement amount acquiring unit acquires the displacement amount based on a correlation between the first characteristic information distribution and the second characteristic information distribution. A subject information acquisition apparatus according to claim 1. 14. The subject information acquiring apparatus according to claim 1, wherein the displacement amount acquiring unit acquires the displacement amount based on a camera image. The subject information acquiring apparatus according to claim 1, wherein the characteristic information acquiring unit acquires an oxygen saturation distribution as the substance concentration distribution. A light source, a conversion element, a characteristic information acquisition unit, a position shift amount acquisition unit, and a display control unit, a control method of the subject information acquisition device including:
The light source generates light of a first wavelength and light of a second wavelength,
The conversion element receives the acoustic wave generated by irradiating the subject with the light of the first wavelength and outputs a first reception signal, and the subject is irradiated with the light of the second wavelength. Receiving the generated acoustic wave and outputting a second received signal;
The characteristic information acquisition unit acquires a first characteristic information distribution based on the first received signal, acquires a second characteristic information distribution based on the second received signal, the first and second Obtaining a substance concentration distribution inside the subject based on the second characteristic information distribution,
The position shift amount obtaining unit obtains a position shift amount between the first characteristic information distribution and the second characteristic information distribution,
The display control unit outputs an image based on the substance concentration distribution and the displacement amount to a display unit,
A method for controlling a subject information acquiring apparatus, comprising:

Images