JP2017039031A - Subject information acquisition device and control method thereof - Google Patents

Abstract

A subject information acquisition apparatus that acquires a photoacoustic wave image and an ultrasonic image provides a technique for performing correction control that can be adjusted by a user independently of the photoacoustic wave image and the ultrasonic image. To do.
A first image is generated using a probe and a photoacoustic wave generated from a subject irradiated with light and received by the probe, transmitted to the subject, reflected, and then probed. Signal processing means for generating a second image using ultrasonic waves received by the probe, display means for displaying the first image and the second image, and the luminance of the first image from the probe A subject having first correction means for correcting according to the distance and second correction means for correcting the luminance of the second image according to the distance from the probe independently of the first correction means. An information acquisition device is used.
[Selection] Figure 1

Description

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

(Photoacoustic tomography)
A photoacoustic tomography technique (Photo Acoustic Tomography, hereinafter referred to as PAT) that acquires functional information of a living body using light and ultrasonic waves has been proposed. PAT has been shown to be particularly useful in the diagnosis of skin cancer and breast cancer, and may be a medical device that replaces an ultrasonic imaging apparatus, an X-ray apparatus, or an MRI apparatus conventionally used in the diagnosis. Expected.

  When a living tissue is irradiated with pulsed light such as visible light or near infrared light, a light-absorbing substance inside the living body, especially a substance such as hemoglobin in the blood, absorbs the energy of the pulsed light and expands instantaneously. A photoacoustic wave (typically an ultrasonic wave) is generated. This phenomenon is called a photoacoustic effect, and PAT visualizes biological tissue information by measuring photoacoustic waves. By visualizing the light energy absorption density distribution (the density distribution of the light absorbing substance in the living body that is the source of the photoacoustic wave) as information on the living tissue, it is possible to image active angiogenesis by the cancer tissue. Moreover, functional information such as oxygen saturation of blood can be obtained by utilizing the light wavelength dependency of the generated photoacoustic wave.

  Furthermore, the PAT technique has a great advantage in terms of patient burden because it allows non-explosive and non-invasive image diagnosis because light and ultrasonic waves are used for imaging biological information. Therefore, it is expected to be used in breast cancer screening and early diagnosis in place of X-ray devices that are difficult to diagnose repeatedly.

In PAT, based on the measurement principle of photoacoustic, light absorbing material to calculate the initial sound pressure P _o of the photoacoustic wave generated as a result of absorbing light in the following equation (1).
P _o = Γ · μ _a · Φ (1)
Here, Γ is the Gruneisen coefficient, which is obtained by dividing the product of the square of the volume expansion coefficient β and the speed of sound c by the constant pressure specific heat C _p . Γ is known to have a substantially constant value depending on the subject, μ _a is the light absorption coefficient of the light absorbing material, Φ is the amount of light inside the subject, that is, the amount of light actually reaching the light absorbing material (light Fluence).

According to equation (1), since the initial sound pressure P _o is dependent on the product of the optical absorption coefficient mu _a light amount [Phi, photoacoustic wave generated when the light amount is larger as the light absorption coefficient was small value larger Become. The same applies to the case where the light absorption coefficient is large even if the amount of light is small.
Incidentally, the distribution of the product of the initial sound pressure distribution P _o by dividing the Gurunaizen coefficient gamma mu _a and [Phi, i.e. the optical energy absorption density distribution can be calculated. Initial sound pressure distribution P _o is obtained by measuring the time variation of the sound pressure P of the photoacoustic wave reaching the ultrasonic probe and propagates inside the subject.

Furthermore, in order to calculate the distribution of the object inside the optical absorption coefficient mu _a, which is a diagnosis target, it is necessary to calculate the distribution of the light intensity Φ in the subject. Since the measurement light penetrates into the deep part of the subject while being strongly diffused and attenuated inside the subject, the amount of light Φ actually reaching the light-absorbing substance is calculated from the light attenuation amount and the penetration depth in the subject. When the surface condition of the subject is irradiated with pulsed light having a uniform light amount, the boundary condition is determined on the assumption that the light propagates on the plane wave inside the subject. ).
Φ = Φ ₀ · exp (−μ _eff · d) (2)
Here, μ _eff is the average effective light attenuation coefficient of the subject, and Φ ₀ is the amount of pulsed light irradiated on the subject, that is, the amount of light on the subject surface. D is the distance from the light irradiation region on the surface of the subject to the light-absorbing substance that emits the photoacoustic wave.

As described above, the light absorption coefficient distribution μ _a can be calculated from the equation (1) and the light energy absorption density distribution μ _a Φ.

(Ultrasonic measurement)
The ultrasonic measurement apparatus transmits an ultrasonic beam formed by synthesizing a plurality of ultrasonic waves using an ultrasonic probe (hereinafter sometimes simply referred to as a probe) to a subject. And the information of the tissue in a subject is obtained by receiving the ultrasonic echo reflected in the inside of a subject. Further, by repeating the ultrasonic measurement while two-dimensionally scanning the subject with the ultrasonic beam, the morphological information of the tissue in the subject can be measured and visualized three-dimensionally.

  Ultrasound measurement can detect the specificity of the tumor (for example, differences in breast cancer, cyst, solids, etc.) in breast cancer diagnosis in the mammary gland, detect lobular cancer, and determine the position and shape of the tumor in the depth direction. It can be recognized and is widely used as a diagnostic device. The ultrasonic diagnostic apparatus has a great advantage in terms of patient burden since it can non-invasively measure tissue in a living body by acoustic measurement using ultrasonic waves. Therefore, it is used for screening and early diagnosis of breast cancer in place of other diagnostic devices that are difficult to diagnose repeatedly.

  In general, in breast cancer diagnosis, benign / malignant diagnosis is comprehensively performed based on the results of palpation and image diagnosis with a plurality of modalities. Patent Document 1 discloses a technique for performing image diagnosis based on a plurality of modalities while maintaining the same state of a subject as a technique for improving the accuracy of breast cancer diagnosis. According to this technique, it is possible to acquire a photoacoustic wave image and an ultrasonic image that visualize active angiogenesis due to breast cancer based on the principle of photoacoustic while keeping the state of the subject identical.

  Further, in Patent Document 2, taking into account the attenuation characteristic of the amount of light accompanying the penetration of pulsed light into the subject, the photoacoustic wave generated inside the subject is in accordance with the time it takes to reach the probe. TGC (Time Gain Control) control for increasing or decreasing the amplification gain is disclosed. By TGC control, a photoacoustic wave image having a uniform luminance level can be obtained regardless of the measurement depth.

However, it has been reported so far in Non-Patent Document 1 and the like that μ _eff in the breast varies greatly _depending on the subject. Strongly depends on the damping characteristics mu _eff of light intensity Φ in the subject, due to variation in the mu _eff, light amount difference even when compared with the same Hitatachi depth that extends to more than 10 times Yes, the optimum correction value for the measurement depth differs for each subject.

Japanese Patent No. 4448189 JP 2010-015535 A

JOURNAL OF BIOMEDICAL OPTICS 1 (3), 330-334 (JULY 1996)

  In order to obtain a photoacoustic wave image having a uniform luminance level regardless of the measurement depth, the attenuation characteristic of the light amount accompanying the penetration of pulsed light into the subject and the photoacoustic wave generated inside the subject are searched. It is preferable to correct the measurement depth by a combination of attenuation characteristics until reaching the touch element. The attenuation characteristic of the amount of light inside the subject is expressed by Equation (2), and the attenuation characteristic of the acoustic wave in the living body generally shows an exponential function characteristic.

  The same can be said for obtaining an ultrasonic image having a uniform luminance level regardless of the measurement depth. In other words, measurement is performed in view of the attenuation characteristics of the ultrasonic wave until it reaches the inside of the subject by transmitting ultrasonic waves, and the attenuation characteristic of the ultrasonic wave until the ultrasonic echo reflected inside the object reaches the probe. It is preferable to correct the depth.

  Further, in most cases, the attenuation characteristic of the light amount and the attenuation characteristic of the photoacoustic wave and the ultrasonic wave are not uniform in the subject. Therefore, it is required to improve the accuracy of measuring the distribution of each attenuation characteristic (that is, attenuation coefficient). For this purpose, for example, an apparatus or method for directly measuring each attenuation coefficient, or a calculation method for estimating from an information that can be indirectly measured has been studied. However, there are problems such as complicated work in diagnosis and high cost of the apparatus and processing, and implementation is not easy.

  As described above, there is a potential difference in image characteristics in the depth direction due to the difference in attenuation characteristics of each measurement principle between the photoacoustic wave image and the ultrasonic image. . In addition, in order to obtain an image that is easier to observe, it is necessary to provide the user with a correction means for controlling the correction.

  The present invention has been made in view of the above problems, and in an object information acquisition apparatus that acquires a photoacoustic wave image and an ultrasonic image, the photoacoustic wave image and the ultrasonic image are independently adjusted and adjusted by the user. An object of the present invention is to provide a technique for performing possible correction control.

The present invention employs the following configuration. That is,
With a probe,
A first image is generated using a photoacoustic wave generated from a subject irradiated with light and received by the probe, and the probe is transmitted to the subject and reflected by the subject. Signal processing means for generating a second image using the received ultrasonic waves;
Display means for displaying the first image and the second image;
First correction means for correcting the luminance of the first image according to the distance from the probe;
Second correction means for correcting the brightness of the second image according to the distance from the probe independently of the first correction means;
A subject information acquisition apparatus characterized by comprising:

The present invention also employs the following configuration. That is,
A method for controlling an object information acquiring apparatus having a probe, signal processing means, display means, first correction means and second correction means,
The probe receives a photoacoustic wave generated from a subject irradiated with light; and
The signal processing means generating a first image using the photoacoustic wave;
The probe receives ultrasonic waves transmitted to the subject and reflected by the subject; and
The signal processing means generating a second image using the ultrasound; and
The display means displaying the first image and the second image;
The first correcting means correcting the luminance of the first image according to the distance from the probe;
A second step in which the second correction means corrects the luminance of the second image according to the distance from the probe independently of the first correction means;
A control method for a subject information acquiring apparatus.

  According to the configuration of the present invention, in the subject information acquisition apparatus that acquires a photoacoustic wave image and an ultrasonic image, correction control that can be adjusted by the user independently is performed on the photoacoustic wave image and the ultrasonic image. Technology can be provided.

1 is a schematic diagram of a device configuration of a subject information acquisition device according to Embodiment 1. FIG. 5 is a flowchart showing acquisition and correction of subject information in the first embodiment. FIG. 3 is a conceptual diagram illustrating object information correction means according to the first embodiment. FIG. 3 is a conceptual diagram illustrating a method for correcting subject information according to the first embodiment. 5 is a flowchart for explaining correction of subject information in the first embodiment. 9 is a flowchart for explaining initial correction of subject information in the second embodiment. 10 is a flowchart showing acquisition and adjustment of subject information in the third embodiment. FIG. 9 is a conceptual diagram for explaining subject information correction means according to a fourth embodiment. FIG. 9 is a conceptual diagram illustrating a method for correcting subject information according to a fourth embodiment.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. However, the dimensions, materials, shapes, and relative arrangements of the components described below should be changed as appropriate according to the configuration of the apparatus to which the invention is applied and various conditions. It is not intended to limit the following description.

<Embodiment 1>
The subject information acquisition apparatus according to the present invention visualizes subject information with photoacoustic waves and ultrasonic waves to generate an image. A subject information acquisition apparatus according to the present invention is configured to transmit an ultrasonic wave to a subject and receive an ultrasonic echo signal, and to receive a photoacoustic wave signal generated by irradiating the subject with light. It has a configuration. The correction of the subject information in the present embodiment includes a correction unit for the luminance level in the depth direction with respect to the generated image, and corrects the luminance value of the image according to the operation of the correction unit by the user. Is. The following description will focus on the parts that characterize the present invention.

  Note that the subject information generated by the ultrasound echo signal (hereinafter simply referred to as ultrasound signal) is information reflecting the difference in acoustic impedance of the tissue inside the subject. The object information generated by the photoacoustic wave signal includes the source distribution of acoustic waves generated by light irradiation, the initial sound pressure distribution in the object, or the light energy absorption density distribution derived from the initial sound pressure distribution, , Absorption coefficient distribution, concentration information distribution of substances constituting the tissue. The substance concentration information distribution is, for example, an oxygen saturation distribution, an oxygenated / deoxygenated hemoglobin concentration distribution, or the like. Image data to be displayed on the display can be generated by performing appropriate processing on the subject information.

  The acoustic wave shown in the present invention is typically an ultrasonic wave, and includes an elastic wave called a sound wave, an ultrasonic wave, and an acoustic wave. In particular, an elastic wave generated inside the subject when the subject is irradiated with light such as near infrared light is referred to as a photoacoustic wave. The probe according to the present invention receives ultrasonic waves and photoacoustic waves generated or reflected in the subject.

(Device configuration)
FIG. 1 is a schematic diagram of an apparatus configuration of a subject information acquisition apparatus according to this embodiment. The subject 101 to be measured is, for example, a breast in breast cancer diagnosis in a mammary gland department.

The object information acquisition apparatus includes a probe 102 that transmits / receives ultrasonic waves and receives photoacoustic waves in contact with the object 101, a light source 103 that generates light, and irradiation optics that irradiates the object 101 with light. A system 104 is provided. The apparatus also includes a signal receiving unit 105 that amplifies the signal detected by the probe 102 and converts the signal into a digital signal, and a photoacoustic wave signal processing unit 106 that performs integration processing of the detected photoacoustic wave signal. The apparatus also includes an ultrasonic transmission control unit 107 that applies an ultrasonic transmission drive signal to the probe 102, and an ultrasonic signal processing unit 108 that performs reception focus processing and the like from the detected ultrasonic signal. The apparatus also includes an operation unit 110 for a user (mainly an inspector such as a medical worker) to input an instruction for starting measurement and parameters necessary for the measurement to the apparatus, the acquired photoacoustic wave signal and ultrasonic wave An image construction unit 111 is provided for constructing a photoacoustic wave image and an ultrasonic image from the signal. The apparatus also includes a display unit 112 that displays a configured image and a user interface (UI) for operating the apparatus. The apparatus also receives a variety of user operations via the operation unit 110, generates control information necessary for the measurement operation, and controls each function via the system bus 114. A storage unit 113 that stores setting information is provided.
The signal receiving unit, the photoacoustic wave signal processing unit, the ultrasonic signal processing unit, the signal receiving unit, and the image construction unit correspond to the signal processing means of the present invention in that various types of processing are performed on the acoustic wave to generate an image. . The display unit corresponds to display means of the present invention.

(Probe)
The probe 102 is configured by arranging a plurality of acoustic elements. These acoustic elements detect a photoacoustic wave generated inside the subject when the subject is irradiated with the light 121 and convert it into an electrical signal, thereby obtaining a photoacoustic wave signal.
In the present embodiment, these acoustic elements also have a function of transmitting ultrasonic waves to the subject 101. An ultrasonic signal can be obtained by detecting an ultrasonic echo reflected inside the subject and converting it into an electrical signal. The photoacoustic wave signal described above corresponds to the first electric signal of the present invention, and the ultrasonic signal corresponds to the second electric signal.

  In the present invention, the probe 102 can be of any type. For example, a conversion element using piezoelectric ceramics (PZT) used in a general ultrasonic diagnostic apparatus is used. Further, a capacitance type CMUT (Capacitive Micromachined Ultrasonic Transducer) can also be used. Also, MMUT (Magnetic MUT) using a magnetic film and PMUT (Piezoelectric MUT) using a piezoelectric thin film can be used.

  Note that the probe 102 is preferably a probe configured to be able to transmit ultrasonic waves and to detect both ultrasonic echoes and photoacoustic waves, whereby ultrasonic waves at the same position can be detected. And photoacoustic wave object information can be obtained. However, the object to which the present invention is applied is not limited to this. Individual probes may be installed for ultrasonic transmission / reception and photoacoustic reception for signal processing.

  In addition, an array-type probe in which a plurality of acoustic elements are arranged two-dimensionally so that photoacoustic waves generated and propagated three-dimensionally from a light-absorbing material or the like can be detected with the widest possible solid angle A child is preferred. By using the array-type probe, it is possible to acquire photoacoustic wave and ultrasonic volume data necessary for imaging the subject region on the front surface of the probe. However, a linear scanning probe in which acoustic elements are arranged in a straight line may be used.

Since the propagation path of the photoacoustic wave and the ultrasonic wave is between the probe 102 and the subject 101, it is preferable to obtain a strong acoustic coupling by arranging an acoustic matching material. For example, a gel or gel sheet for ultrasonic measurement can be used as the acoustic matching material.

(Optical system)
The light source 103 emits pulsed light (width of 100 nsec or less) having a center wavelength in the near infrared region of 530 to 1300 nm. As the light source 103, a solid-state laser (for example, a Yttrium-Aluminium-Garnet laser or a Titan-Sapphire laser) capable of emitting a pulse having a center wavelength in the near infrared region is generally used. A laser such as a gas laser, a dye laser, or a semiconductor laser can also be used, and a light-emitting diode or the like can be used as the light source 103 instead of the laser.

  The wavelength of light is selected between 530 nm and 1300 nm according to the light absorbing substance in the living body to be measured. Examples of the light-absorbing substance include oxygenated hemoglobin or deoxygenated hemoglobin, blood vessels containing many of them, and malignant tumors containing many new blood vessels, as well as glucose and cholesterol. For example, when measuring hemoglobin in a new blood vessel of breast cancer, light of 600 to 1000 nm is generally absorbed. On the other hand, light absorption of water constituting the living body is minimized near 830 nm, so light is absorbed at 750 to 850 nm. Becomes relatively large. Moreover, since the light absorption rate changes for each light wavelength depending on the state of hemoglobin (oxygen saturation), functional changes in the living body can be measured by utilizing this wavelength dependency.

  The irradiation optical system 104 guides the pulsed light emitted from the light source 103 toward the subject, and forms and emits light 121 suitable for measurement. The irradiation optical system 104 is typically configured by optical components such as a lens or prism that collects or expands light, a mirror that reflects light, or a diffusion plate that diffuses light. An optical waveguide such as an optical fiber can also be used for light guide from the light source 103 to the subject 101.

  Note that, as a safety standard regarding irradiation of laser light or the like to the skin or eyes, generally, the maximum allowable exposure amount (Maximum Permissible Exposure) is determined by IEC 60825-1 according to conditions such as light wavelength, exposure duration, and pulse repetition. . The irradiation optical system 104 generates light 121 having a shape and an emission angle suitable for imaging the subject region on the front surface of the probe 102 while ensuring safety in accordance with such a standard. In FIG. 1, the irradiation optical system 104 is arranged only on one side of the probe 102, but the actual arrangement is not limited to this. For example, by irradiating the probe 102 with light from both sides, the subject region on the front surface of the probe 102 can be illuminated more uniformly.

  Further, the irradiation optical system 104 includes an optical configuration (not shown) that detects the emission of the light 121 to the subject 101 and generates a synchronization signal for controlling the reception and recording of the photoacoustic wave signal in synchronization therewith. . The emission of the light 121 can be detected by dividing a part of the pulsed light generated by the light source 103 by an optical system such as a half mirror and guiding it to the optical sensor, and using a detection signal generated by the optical sensor. When a bundle fiber is used for light guide of pulsed light, it can be detected by branching a part of the fiber and guiding it to an optical sensor. The synchronization signal generated by this detection is input to the signal receiving unit 105.

(Signal processing system)
The signal receiving unit 105 amplifies the photoacoustic wave signal or the ultrasonic signal generated by the probe 102 in accordance with the synchronization signal transmitted from the irradiation optical system 104 or the ultrasonic transmission control unit 107 and converts it into a digital signal. The signal reception unit 105 includes a signal amplification unit that amplifies the analog signal generated by the probe 102 and an A / D conversion unit that converts the analog signal into a digital signal.

  The photoacoustic wave signal processing unit 106 corrects the sensitivity variation of the acoustic element of the probe 102 and the physical or electrical missing element for the digital signal of the photoacoustic wave generated by the signal receiving unit 105. Complement processing, integration processing for noise reduction, etc. are performed. By accumulating processing, it is possible to repeatedly acquire photoacoustic wave signals at the same position of the subject 101 and perform cumulative averaging processing to reduce system noise and improve the S / N ratio of the photoacoustic wave signal. .

  A photoacoustic signal obtained by detecting a photoacoustic wave emitted from a light-absorbing substance inside the subject 101 is generally a weak signal. Therefore, a photoacoustic wave image suitable for image diagnosis is obtained by irradiating the light 121 a plurality of times and accumulating a plurality of photoacoustic wave signals obtained by each irradiation to improve the S / N ratio. Can do.

  The ultrasonic transmission control unit 107 generates and applies a drive signal to be applied to each acoustic element constituting the probe 102, and controls the frequency and sound pressure of the ultrasonic wave to be transmitted. In this embodiment, in an array-type probe in which a plurality of acoustic elements are arranged two-dimensionally, linear scanning of ultrasonic beam transmission and ultrasonic echo reception is performed along one direction constituting the array. After that, the linear scan is repeated in the other direction. Thereby, three-dimensional ultrasonic data composed of a plurality of B-mode images can be obtained.

  The ultrasonic transmission control unit 107 sets a transmission direction of the ultrasonic beam and selects a transmission delay pattern corresponding to the transmission direction, and sets a reception direction of the ultrasonic echo and corresponds to the reception direction. And a reception control function for selecting a reception delay pattern. The transmission delay pattern is a pattern of delay times given to a plurality of drive signals in order to form an ultrasonic beam in a predetermined direction by ultrasonic waves transmitted from a plurality of acoustic elements. The reception delay pattern is a delay time pattern given to a plurality of reception signals in order to extract ultrasonic echoes from an arbitrary direction with respect to the ultrasonic signals detected by the plurality of acoustic elements. These transmission delay pattern and reception delay pattern are stored in the storage unit 113.

  Based on the reception delay pattern selected by the ultrasonic transmission control unit 103, the ultrasonic signal processing unit 108 corresponds to each delay time for the ultrasonic digital signal generated by the signal receiving unit 105, The reception focus processing is performed by adding the respective signals. Ultrasonic data with a focused focus is generated by this process. In addition, a B-mode image is generated through logarithmic compression or filter processing.

  The control processor 109 operates an operating system (OS) that performs basic resource control and management in the program operation. And the program code stored in the memory | storage part 113 is read, and the function of embodiment described afterwards is performed. In particular, in response to event notifications generated by various operations such as imaging start instructions and interruptions from the user via the operation unit 110, the object information acquisition operation is managed, and each hardware is connected via the system bus 114. Control.

  In addition, the control processor 109 acquires parameters for acquiring object information designated by the operation unit 110 or set in the storage unit 113 in advance. Based on the parameter, laser light emission control information necessary for satisfying the number of integration of the photoacoustic wave signal is output to the light source 103 and the photoacoustic wave signal processing unit 106. Similarly, control information relating to ultrasonic transmission / reception control operations such as transmission of ultrasonic beams and reception of ultrasonic echoes such as a plurality of focus settings is output to the ultrasonic transmission control unit 107 and the ultrasonic signal processing unit 108.

  In addition to this, the control unit processor 109 manages the device state by managing the identification information for identifying the device individual and the information set for the individual, and monitoring the state of each hardware.

  Based on the acquired digital signal and ultrasonic data of the photoacoustic wave, the image construction unit 111 images the tissue information in the subject and superimposes any tomographic image of the photoacoustic wave image and the ultrasonic image, or those Configure the displayed image. Further, various correction processes such as luminance correction, distortion correction, and region-of-interest extraction are applied to the configured image to configure information more preferable for diagnosis. Further, according to the operation of the operation unit 110 by the user, adjustment of parameters and display image regarding the configuration of the photoacoustic wave image, the ultrasonic image, or the superimposed image thereof is performed. The photoacoustic wave image corresponds to the first image of the present invention, and the ultrasonic image corresponds to the second image.

  A photoacoustic wave image is obtained by performing image reconstruction processing on a digital signal of a three-dimensional photoacoustic wave generated by detecting a plurality of acoustic elements arranged in an array. The photoacoustic wave image can visualize object information such as characteristic distribution such as acoustic impedance and optical characteristic value distribution. As the image reconstruction processing, for example, back projection in the time domain or Fourier domain generally used in the tomography technique, or phasing addition processing is used. If time constraints are not strict, image reconstruction methods such as inverse problem analysis by iterative processing can be used, and image reconstruction can be performed by using a probe with a reception focus function such as an acoustic lens. It is also possible to visualize the subject information without performing the process.

  The image configuration unit 111 is generally configured using a GPU (Graphics Processing Unit) having a high-performance arithmetic processing function and a graphic display function. As a result, the time required for image reconstruction processing and display image configuration can be reduced.

  The storage unit 113 includes a memory necessary for the operation of the control processor 109, a memory for temporarily storing data during the object acquisition operation, a generated photoacoustic wave image or ultrasonic image, and related object information. It is composed of a storage medium such as a hard disk that stores diagnostic information and the like. And the program code of the software which implement | achieves the function of embodiment described hereafter is stored. Also, factory default values and default parameters are stored as parameters related to the object information acquisition operation. The default parameter reflects a parameter setting often used when the object information acquisition operation is repeatedly performed, and can be updated as appropriate by the user. By holding the default parameters, it is possible to eliminate the complexity of setting all the parameters every time when the object information is acquired.

  Note that the default value may be stored and held separately for each individual object information acquisition apparatus, connected hardware such as the probe 102, and for each object 101 and user.

(interface)
The display unit 112 displays the photoacoustic wave image and the ultrasonic image configured by the image configuration unit 111, or a superimposed image thereof, and a UI for operating the image and the apparatus. In general, a liquid crystal display is used, but any type of display such as an organic EL (Electro Luminescence) may be used.

  The operation unit 110 is an input device for a user to specify parameters relating to an object information acquisition operation, such as the number of times of acoustoacoustic image integration and reception gain settings for photoacoustic waves and ultrasonic waves. Further, it includes a photoacoustic wave correction unit 110A and an ultrasonic wave correction unit 110B, and also has a function for performing an image processing operation relating to an image. Generally, it is composed of a mouse, a keyboard, a touch panel, and the like, and notifies an event to software such as an OS operating on the control processor 109 in accordance with a user operation.

In the subject information acquiring apparatus having the above configuration, the same subject region is used except when the probe position / posture changes by using a probe capable of detecting photoacoustic waves and ultrasonic waves. The photoacoustic wave image and the ultrasonic image can be acquired at once in one object information acquisition operation. In addition, the same photoacoustic wave image and ultrasonic image are displayed side by side, or a superimposed image thereof is generated and displayed, thereby assisting the user in observing, analyzing, and diagnosing subject information. Further, by providing independent brightness correction means for the photoacoustic wave image and the ultrasonic image, brightness correction can be performed so that the user can easily observe without depending on the attenuation characteristics based on the respective measurement principles. it can.

(Processing flow)
Next, with reference to FIG. 2, a flow showing the flow of obtaining object information in the first embodiment will be described. The flowchart of FIG. 2 is implemented when the user instructs acquisition of subject information via the operation unit 110.

  In step S <b> 201, the light source 103 emits pulsed light in accordance with a light emission start instruction related to acquisition of object information from the control processor 109. The pulsed light emitted from the light source 103 is shaped by the irradiation optical system 104 and irradiated onto the subject 101 as light 121. The irradiation optical system 104 generates a synchronization signal simultaneously with the emission of the light 121 to the subject 101 and sends it to the signal receiving unit 105.

  In step S202, a photoacoustic wave signal is acquired. Specifically, the probe 102 first detects a photoacoustic wave generated from the subject 101 and generates an analog electric signal (photoacoustic wave signal). Then, the signal receiving unit 105 starts receiving the photoacoustic wave signal in synchronization with the synchronization signal generated by the irradiation optical system 104 and converts it into a digital signal. The signal receiving unit 105 that has received the synchronization signal receives a photoacoustic wave signal by a predetermined number of samples at a sampling rate operable from that moment. The number of samples is determined in consideration of the propagation speed of the acoustic wave in the subject and the maximum measurement depth as a device specification.

  In step S203, the photoacoustic wave signal processing unit 106 performs integration processing using the photoacoustic wave digital signal generated in step S202.

  In step S204, it is determined whether or not the number of photoacoustic wave signals specified by the user or set in advance is satisfied. If the signal integration count is not satisfied, the process proceeds to step S201 and the acquisition of the photoacoustic wave signal is repeated. If the signal integration count is satisfied, the process proceeds to step S205.

  In step S205, the image construction unit 111 generates a photoacoustic wave image using the integrated photoacoustic wave signal obtained up to step S204. In general, the reconfiguration process takes time, and since the process can be outsourced to the GPU, the subsequent processes can be performed in parallel. When generating an image, for example, the UBP (Universal Back-Projection) method, which is an image reconstruction method in the time domain, can be used.

  In step S206, the subject is scanned with ultrasound. Specifically, first, the control processor 109 instructs the ultrasonic transmission control unit 107 to start acquiring an ultrasonic B-mode image. The ultrasonic transmission control unit 107 performs linear scanning of ultrasonic beam transmission and ultrasonic echo reception based on a plurality of parameters such as focus settings. In addition, the ultrasonic control unit 105 transmits a synchronization signal to the signal receiving unit 105 simultaneously with the transmission of the ultrasonic beam. The ultrasonic echo is detected by the probe 102, and the signal receiving unit 105 that has received the synchronization signal receives the ultrasonic signal for a predetermined number of samples at an operable sampling rate and converts it into a digital signal. .

In step S207, the ultrasonic signal processing unit 106 performs phasing addition processing, logarithmic compression, filter processing, and the like on the ultrasonic digital signal obtained in step S206 to generate a B-mode image (ultrasonic image). To do.

  In step S208, initial correction is performed on the photoacoustic wave image. The initial correction is a correction process performed for each ultrasonic image and photoacoustic wave image according to the characteristics. As the initial correction of the photoacoustic wave image, for example, there is a process of giving a gain to the intensity of the photoacoustic wave detected from the reconstruction target part according to the amount of light reaching the part. At the time of initial correction, a default correction value stored in advance in the storage unit 113 or a correction value calculated after estimating the light attenuation characteristic is applied to the photoacoustic wave image. The initial correction may be executed by a component having an image processing function such as the photoacoustic wave signal processing unit 106 or the image configuration unit 111.

  The light attenuation characteristics (light attenuation coefficient distribution) in the living body, that is, the scattering shape of the light 121 is theoretically calculated by a light transport equation or a light diffusion equation derived by approximation. The light attenuation coefficient may be calculated using a finite element method, which is a numerical calculation method, based on information such as the light wavelength of the light 121 and the shape when the subject is incident. Since the shape of the light 121 when the subject is incident is determined by the design of the irradiation optical system 104, the design data of the illumination optical system 104 may be used. Or the data measured using the energy meter etc. which can measure a light shape may be sufficient. The shape data is stored in the storage unit 113 in advance.

  In step S209, initial correction is performed on the ultrasound image. At this time, a default correction value stored in advance in the storage unit 113 or a correction value calculated in consideration of the signal attenuation of the ultrasonic wave indicating the characteristic of the exponential function is applied to the ultrasonic image. The correction values calculated in steps S208 and S209 are reflected on the initial positions of correction value control points 304A to 304G and 308A to 308G on the UI described later together with image display.

  In step S210, the image construction unit 111 generates a superimposed image using the photoacoustic wave image and the ultrasonic image corrected in steps S208 and S209. The generated superimposed image is displayed on the display unit 112.

  In step S211, superimposed image correction processing is performed. Details will be described later.

  In step S212, it is determined whether or not an operation event for ending image observation for breast cancer diagnosis has been notified. When the image observation is finished, a series of flows for obtaining the subject information is finished. When continuing without ending image observation, the process proceeds to step S211, image correction is repeated, and image display is continued.

  Through the above processing, two pieces of object information based on the photoacoustic wave image and the ultrasonic image can be acquired at once in one operation for acquiring the object information.

  In this flowchart, the acquisition of the ultrasonic image is started after the generation of the photoacoustic wave image. However, in some cases, the ultrasonic image can be acquired in the interval of repeating the reception of the photoacoustic wave signal for integration. The reception period of the photoacoustic wave signal is determined by the repetition frequency of light emission of the light source 103. For example, in the case of a laser capable of emitting pulses at 10 Hz, the reception period is 100 msec. For example, if the photoacoustic wave signal reception time is 30 μsec, there is a waiting time of approximately 99 msec until the next photoacoustic wave signal is received. If the time required for transmitting an ultrasonic beam and receiving an ultrasonic echo is 60 μsec, for example, if ultrasonic transmission / reception is performed 128 times to generate a B-mode image, the time is approximately 12.8 msec with 100 μsec × 128 lines. The reception of the sound wave signal can be completed. Therefore, it is possible to implement the photoacoustic wave signal and the ultrasonic signal in a time division manner within a period of 100 msec.

  FIG. 3 is a conceptual diagram illustrating object information correcting means in the first embodiment. The correction unit in the present embodiment is provided as a UI displayed on the display unit 112. The application of the present invention is not limited to the configuration based on the software UI, and the function of the correction means may be provided by hardware such as a slide bar or a dial.

  Reference numeral 301 indicates an image obtained by superimposing a photoacoustic wave image and an ultrasonic image on an arbitrary cross section of the subject. For example, among the ultrasonic B-mode images acquired by the probe 102, the central one B-mode image is an image in which a tomographic image of a photoacoustic wave image indicating the same subject region is superimposed. The superimposed image 301 in this embodiment is a visualization of a subject region having a width of 32 mm (y-axis direction) × depth of 40 mm (z-axis direction), for example. In addition, it is assumed that the photoacoustic wave image and the ultrasonic image are configured with 12-bit gradation 4096 gradation per pixel. In FIG. 3, the z-axis indicates the depth direction as viewed from the probe surface, that is, the measurement depth direction. Therefore, the z-axis value indicates the distance from the probe. Further, the y-axis indicates the same direction as the ultrasonic linear scan direction.

  The superimposed image is obtained by superimposing a photoacoustic wave image on an ultrasonic image base. The ultrasonic image shows highly accurate morphological information regarding the contour shape of the tissue in the subject, the position in the depth direction (distance from the probe), and the like. The photoacoustic wave image visualizes the distribution of active angiogenesis due to breast cancer and shows functional quantities such as the amount of oxygen in the blood. Therefore, in the diagnosis using the superimposed image, it is possible to observe the form of the tissue and its functional amount in an intuitive manner.

  In addition, when superimposing a photoacoustic wave image on an ultrasonic image, the image grasping | ascertainment at the time of a diagnosis can be made easy by setting the opacity of a photoacoustic wave image. At this time, there is a method of determining the opacity of the pixel in a form corresponding to the luminance value of the photoacoustic wave image as it is, or transparentizing a luminance value region below a certain value that does not show a significant functional quantity.

  In the superimposed image, generally, the luminance value of the ultrasonic image indicating the morphological information of the tissue is a gray scale indicating light and dark as it is, and the luminance value of the photoacoustic wave image indicating the functional amount is, for example, from the minimum value blue to an intermediate value. It is expressed with a color scale that reaches the maximum value of red via green. Thereby, an image can be grasped intuitively.

  In the superimposed image 301 in FIG. 3, a light absorbing material (reference numerals 322 and 323) visualized in a photoacoustic wave image and a tissue (reference numerals 321 and 324) visualized in an ultrasonic image are shown.

  Reference numeral 302 denotes a color scale that is a legend of luminance values of the photoacoustic wave image. Reference numeral 303 denotes a photoacoustic wave image correcting unit, which is a UI corresponding to the photoacoustic wave correcting unit 110A. Reference numeral 306 denotes a gray scale that is a legend of luminance values of the ultrasonic image. Reference numeral 307 denotes an ultrasonic image correcting unit, which is a UI corresponding to the ultrasonic correcting unit 110B. The correction means 303 and 307 in the first embodiment are correction means for correcting the luminance values of the photoacoustic wave image and the ultrasonic image, respectively.

  In the photoacoustic wave image correcting means 303, control points for setting correction values of 304A, 304B, 304C, 304D, 304E, 304F, and 304G are arranged. The user can individually set the correction value according to the depth for the photoacoustic wave image. By operating the control points 304A to 304G, the light absorbing material 322 or 323 can be turned off or highlighted.

In addition, regarding the attenuation characteristic with respect to the depth direction of a photoacoustic wave image, the attenuation characteristic of light and the attenuation characteristic of a photoacoustic wave each show an exponential characteristic. Therefore, the correction value curve (arrangement of the control points 304A to 304G) for the combination is approximately along a logarithmic function.

  Similarly, control points for setting correction values of 308A, 308B, 308C, 308D, 308E, 308F, and 308G are also arranged in the ultrasonic image correction unit 307. The user can individually set the correction value according to the depth for the ultrasonic image. By operating the control points 308A to 308G, the display of the tissue 321 or 324 can be erased or highlighted.

  In addition, regarding the attenuation characteristic with respect to the depth direction of the ultrasonic image, the attenuation of the ultrasonic wave exhibits an exponential characteristic. Therefore, the correction value curve (arrangement of the control points 308A to 308G) has an approximately logarithmic function arrangement.

  When the user observes the superimposed image 301, there is a case where one of the images is emphasized with high luminance or is displayed with low luminance and is conservatively displayed. Therefore, it is preferable that the photoacoustic wave image correcting unit 303 and the ultrasonic image correcting unit 307 are arranged close to each other. In FIG. 3, the photoacoustic wave image correcting unit 303 and the ultrasonic image correcting unit 307 are arranged vertically, but by arranging them side by side, it is easy to operate the correcting units 303 and 307 alternately, and image observation is performed. The complexity of user operations at the time can be eliminated.

  Further, when operating the correction means 303 and 307 while observing the superimposed image 301, it is not preferable that the line of sight moves greatly and the superimposed image 301 is out of the field of view. Therefore, as shown in FIG. 3, by arranging the superimposed image 301 and the correcting means 303 and 307 side by side, the correcting means 303 and 307 can be captured in the peripheral visual field in the visual field for observing the superimposed image 301, or the movement of the line of sight Can be suppressed as much as possible.

  In FIG. 3, the correction means 303 and 307 provide a correction value setting function by arranging seven control points in the depth direction of the image. However, a necessary number according to the measurement depth is provided. Only need to be arranged. Further, a different number of control points may be arranged in the correction means 303 and 307.

  Next, a method for correcting subject information in the present embodiment will be described with reference to FIG. FIG. 4A shows an example of operating the photoacoustic wave image correcting unit 303 shown in FIG. 3, and FIG. 4B shows an example of a correction value curve calculated as a result of the operation.

  The user sets a correction value by dragging the control points 304A, 304B, 411C, 304D, 304E, 304F, and 304G via the operation unit 110. When the user drags each control point, the correction unit 303 notifies the control processor 109 of a position value change event. For example, while the user is dragging the control point 411C, the correction unit 303 sequentially notifies a change in value indicating the position of the control point. Upon receiving the notification, the control processor 109 sequentially generates and displays a photoacoustic wave image reflecting the new correction value after the operation.

  In this embodiment, moving the control point to the right increases the effect of brightness correction, and moving it to the left decreases the effect of brightness correction. For example, when the control point 411C is moved to the setting confirmation position 412C, the correction value at the depth position C is reduced.

When the values of the seven control points discretely arranged along the depth direction of the photoacoustic wave image are set, the correction value curve of FIG. Is calculated. In the example of FIG. 4B, nearest neighbor interpolation is applied to a region shallower than the control point 304A and a region deeper than 304G. For the interpolation calculation between discrete control points, any known interpolation method such as nearest neighbor interpolation, quadratic interpolation, ternary interpolation, polynomial interpolation, etc. may be applied.

In FIG. 4B, the vertical axis represents the depth position of the photoacoustic wave image, and the horizontal axis represents the correction value. A luminance value can be used as the correction value. For example, the correction value (luminance value) may be corrected by simply adding the Min value of 0 and the Max value of 4095 to individual pixel luminance values constituting the photoacoustic wave image.
A magnification can also be used as a correction value. For example, the correction value (magnification) may be corrected by setting the Min value to 0.2, the Max value to 1.8, and the intermediate value to 1.0 and multiplying each pixel luminance value.

  In the present invention, since the user can control the correction value to a desired value, it can be adjusted so that the user can easily observe. When the correction value is reflected and the upper limit of the gradation of the color scale 202 is exceeded, the upper limit value of the display gradation may be displayed.

  The user can also perform luminance correction on the ultrasonic image by the same operation in the ultrasonic correction unit 307.

  Furthermore, by providing the photoacoustic wave correcting means 303 and the ultrasonic correcting means 307 independently, it is possible to obtain a photoacoustic wave image and an ultrasonic image having a uniform luminance level regardless of the depth, and a superimposed image. This can contribute to improved visibility.

  In FIG. 4, the example in which the user sets the correction value by operating the operation unit 110 using the pointer 401 has been described, but it is also possible to directly operate with a finger using the touch panel. It is also possible to operate the correction value by pressing the cursor key after moving the focus with respect to the control point using the TAB key or the like using the keyboard.

  As described above, the luminance correction of the photoacoustic wave image and the ultrasonic image can be individually performed by using the operation unit 110 in accordance with the UI on the display unit 112. Further, since only the luminance correction is performed on the image, it is possible to quickly respond to the user's correction value operation.

  FIG. 5 is a flowchart showing the flow of subject information correction, that is, image correction (luminance correction) in the present embodiment.

  In step S501, the control processor 109 determines whether a value change event has been notified of the luminance correction control points 304A to 304G of the photoacoustic wave image or the luminance correction control points 308A to 308G of the ultrasonic image. If a value change event has been notified, the process proceeds to step S502. If no value change event has been notified, the process ends.

  In step S502, the control processor 109 calculates the brightness correction value shown in FIG. 4B in accordance with the value change of the brightness correction control point notified in step S501. When the control point of the photoacoustic wave image is operated, the calculation of the luminance correction value is omitted because the current setting value may be maintained for the ultrasonic image. The reverse is also true.

In step S503, the control processor 109 reflects the brightness correction value calculated in step S502 on each brightness value. When the event occurs at the control points 304A to 304G, the luminance value of the photoacoustic wave image is corrected. When the event occurs at the control points 308A to 308G, the luminance value of the ultrasonic image is corrected.

  In step S504, the display of the superimposed image on the display unit 112 is updated with respect to the target image updated by the new brightness correction in step S503.

In the subject information acquiring apparatus having the above configuration, the user can perform luminance correction suitable for observation by separately providing luminance correction means for the photoacoustic wave image and the ultrasonic image having different attenuation characteristics. . In addition, automatic correction according to the attenuation characteristics of the photoacoustic wave and the ultrasonic wave is applied as an initial correction when an image is presented to the user during one acquisition of the subject information. Can do.
As described in the above flowcharts, the photoacoustic wave image is corrected by initial correction by the photoacoustic wave signal processing unit or the image configuration unit, or by an operation by the user through the operation unit (operation unit) or the photoacoustic wave correction unit. Is done. In the present invention, these components correspond to the first correction means. Similarly, the ultrasonic signal processing unit or the image construction unit, the ultrasonic correction unit of the operation unit, and the like correspond to the second correction unit of the present invention.

  In the present embodiment, since the correction value responds in real time following the operation of the control point, the user can intuitively correct the luminance of the photoacoustic wave image and the ultrasonic image. In addition, when observing a superimposed image, the user can change the brightness correction of one image in a short period of time, thereby assisting visual recognition of differences from the other image and the overlap between functional information and morphological information of the tissue in the subject. You can also

  In the present embodiment, the example in which the photoacoustic wave image and the ultrasonic image are presented to the user as superimposed images has been described, but the application of the present invention is not limited to this. The photoacoustic wave image and the ultrasonic image may be presented side by side, or any other presentation method that allows the user to compare these two images.

<Embodiment 2>
A second embodiment of the present invention will be described with reference to the drawings.

In the first embodiment, the attenuation characteristics based on the respective measurement principles are estimated in the process of acquiring the photoacoustic wave image and the ultrasonic image, and the depth correction corresponding to the estimated attenuation characteristics is used as the initial correction. It was automatically applied and presented to the user.
In the present embodiment, for example, when displaying already stored photoacoustic wave image data, initial correction is performed based on image characteristics such as the luminance distribution. Hereinafter, a description will be given focusing on the features characteristic of the present embodiment.

  The apparatus configuration of the subject information acquisition apparatus in the present embodiment is the same as that shown in FIG. Further, the UI presented to the user can also be implemented in the form described with reference to FIGS.

  FIG. 6 is a flowchart for explaining a method for applying initial correction in the object information, particularly photoacoustic waves, in the present embodiment.

  In step S <b> 601, the control processor 109 reads out signal data necessary for generating a photoacoustic wave image stored in the storage unit 113. The photoacoustic wave image data stored in the storage unit 113 is not the image data after the luminance correction by the method of the first embodiment but the data before correction generated from the received photoacoustic wave signal data. is there.

  In step S602, the control processor 109 calculates an average value of a plurality of pixels at the same depth position (position in the z direction shown in FIG. 3) of the image data read in step S601. Alternatively, the luminance level for each of the regions is calculated by equally dividing the region into seven regions in the depth direction. These average values roughly represent the luminance level of the area. Thereby, the luminance distribution is obtained. At this time, the control processor corresponds to the luminance distribution calculating means of the present invention. The luminance distribution calculating means obtains the first luminance distribution of the present invention from the photoacoustic wave image and the second luminance distribution from the ultrasonic image.

  In step S603, the control processor 109 calculates a correction value based on the calculated luminance level for each depth position so that the luminance level is uniform regardless of the depth direction. In other words, a correction value according to the luminance distribution according to the distance from the probe is obtained. For example, in the luminance level calculated for each depth position, when the luminance level is unified with reference to the intermediate value, the correction value for the luminance level exceeding the intermediate value is given a negative correction value by the difference, On the contrary, a positive correction value may be given to a luminance level lower than that. In addition, for example, correction may be performed so that the luminance level of the relatively surface layer region of the subject 101 that can maintain a high S / N in the reception of photoacoustic waves is standardized. The reference in the photoacoustic wave image corresponds to the first reference of the present invention. Similarly, the reference of the ultrasonic image corresponds to the second reference.

  In step S604, as the initial correction for the photoacoustic wave image, the control processor 109 applies the correction value calculated in step S603 to the photoacoustic wave image data read in step S601.

  In step S605, the image construction unit 111 displays the photoacoustic wave image corrected in step S604 on the display unit 112. It is also possible to display a superimposed image with an ultrasonic image acquired in a batch during the acquisition of the same subject information in the past. The correction value calculated in step S603 is reflected on the initial positions of correction value control points 304A to 304G and 308A to 308G on the UI described later together with image display.

According to the object information correction method having the above configuration, when an already stored photoacoustic wave image is read and displayed, an initial correction value is calculated based on a change in luminance level in the depth direction, Applicable to photoacoustic wave images. In most cases, the attenuation characteristics of the amount of light and photoacoustic waves and ultrasonic waves are not uniform in the subject. However, according to the present embodiment, a photoacoustic wave image having a uniform luminance level over the entire measurement depth can be presented to the user without estimating those characteristics. In the present embodiment, the luminance level is represented by the average luminance value. However, the luminance value having the largest distribution amount may be used as the luminance level.
Further, the initial correction can be similarly applied to the ultrasonic image.

<Embodiment 3>
A third embodiment of the present invention will be described with reference to the drawings. In the correction of the subject information according to the present embodiment, the correction value by the correction unit is reflected on the signal reception gain control, that is, the TGC control in the signal processing unit 105. Hereinafter, a description will be given focusing on the features characteristic of the present embodiment.

  The apparatus configuration of the subject information acquisition apparatus in the present embodiment is the same as that shown in FIG. The UI presented to the user can also be implemented in the form described with reference to FIGS.

The signal processing unit 105 in the present embodiment has a TGC (Time Gain) that increases or decreases the amplification gain according to the time that the acoustic wave reaches the probe 102 in addition to the functions in the above embodiment.
Control) can be executed. Generally, a variable gain amplifier that controls an amplification gain by voltage control is used as a circuit for performing TGC control. By configuring the acoustic wave detection signal amplifier with a variable gain amplifier, it becomes possible to perform TGC control for controlling the variable gain control signal together with the acoustic wave reception time.
The TGC control is a technique that is generally used in an ultrasonic diagnostic apparatus, and its purpose is to correct the attenuation of the ultrasonic wave in the subject. More specifically, monotonically increasing gain control is performed for the exponential attenuation characteristics of the ultrasonic waves.

  In addition, according to the technique of Patent Document 2, in order to obtain a photoacoustic wave image having a uniform luminance level regardless of the measurement depth, in consideration of the attenuation characteristic of the light amount inside the subject of the pulsed light, TGC control that increases or decreases the amplification gain of the photoacoustic wave according to the arrival time to the probe is also possible.

  FIG. 7 is a flowchart showing a flow of obtaining object information in the present embodiment. The flowchart in FIG. 7 is implemented when the user instructs acquisition of subject information via the operation unit 110. The difference from the flowchart of FIG. 2 is steps S701, S702, and S703.

  In step S <b> 701, the control processor 109 reads the set values at the present time of the photoacoustic wave image correcting unit 303 and the ultrasonic image correcting unit 307.

  In step S <b> 702, the control processor 109 generates a reception gain table for the photoacoustic wave signal storing the reception gain value for each reception sample in accordance with the setting of the photoacoustic wave image correction unit 303, and sends it to the signal reception unit 105. Set. The reception gain table is the same as the correction value curve shown in FIG. 4B. For example, the vertical axis represents the number of received samples along the time series of the signal reception unit, and the horizontal axis represents the signal amplification unit of the signal processing unit 105. Or array data with amplification gain in the A / D converter. The signal receiving unit 105 performs TGC control according to the reception gain table.

In steps S201 to S204, as in the first embodiment, a photoacoustic wave signal that satisfies a signal integration count specified in advance is acquired. However, in step S202 in the present embodiment, a photoacoustic wave signal subjected to TGC control according to the reception gain table set in step S701 is obtained.
In step S205, the image construction unit 111 generates a photoacoustic wave image based on the signal subjected to TGC control.

  In step S <b> 703, the control processor 109 generates an ultrasonic signal reception gain table in accordance with the setting of the ultrasonic image correction unit 307 and sets it in the signal receiving unit 105.

  In step S206, the ultrasonic transmission control unit 107 performs a linear scan of transmission of an ultrasonic beam and reception of an ultrasonic echo. When receiving an ultrasonic echo, the signal receiving unit 105 performs TGC control according to the reception gain table set in step S703.

  In step S207, the ultrasonic signal processing unit 106 performs phasing addition processing, logarithmic compression, filter processing, and the like on the ultrasonic digital signal obtained after the TGC control obtained in step S206. To generate a B-mode image.

  In step S <b> 210, the image construction unit 111 constructs a superimposed image using the photoacoustic wave image and the ultrasonic image generated as a result of steps S <b> 205 and S <b> 207, and displays them on the display unit 112.

According to the subject information acquiring apparatus having the above-described configuration, a signal is received from the photoacoustic wave image correcting unit 303 and the ultrasonic image correcting unit 307 in one operation of acquiring subject information. The function of receiving gain control is given. As a result, a photoacoustic wave image and an ultrasonic image on which TGC control has been performed can be acquired collectively. In the present embodiment, the first correcting means of the present invention includes a control processor that controls the TGC process on the photoacoustic signal and a signal receiving unit that executes the control processor. Similarly, the second correction means also includes a TGC control function by the control processor for the ultrasonic signal and an amplification function by the signal receiving unit.

  Note that the series of processing in the flowchart of FIG. 7 has been described as being completed by one acquisition of the subject information with respect to one acquisition instruction. By repeatedly executing this flowchart at a constant cycle, the apparatus can follow the user's continued correction operation within a predetermined time. Brightness correction means are provided separately for the photoacoustic wave image and the ultrasonic image with different attenuation characteristics, and by responding to the correction operation of the user in real time within a fixed time, it is possible to adjust the TGC control suitable for observation. User operations can be further assisted.

<Embodiment 4>
Embodiment 4 of the present invention will be described with reference to the drawings. The object information correction method of this embodiment is to return the luminance value correction or the reception gain correction setting in the depth direction of the photoacoustic image and ultrasonic image to the initial values performed in each of the above examples. .

  The apparatus configuration of the subject information acquisition apparatus in the present embodiment is the same as that shown in FIG. Further, the flowchart relating to the acquisition of the subject information is the same as that shown in FIG. 3, and the UI presented to the user can also be implemented in the form described with reference to FIGS.

  FIG. 8 is a conceptual diagram illustrating object information correcting means in the present embodiment. The correction unit in the present embodiment is provided as a UI displayed on the display unit 112. The application of the present invention is not limited to the configuration based on the software UI, and the function of the correction means may be provided by hardware such as a slide bar or a dial.

  In addition to the UI of FIG. 2 in the first embodiment, new functions are arranged. Reference numeral 801 denotes a reset button for the correction value of the photoacoustic wave image, and reference numeral 802 denotes a default setting button for updating the default correction value for the photoacoustic wave image held in the storage unit 113. In the present embodiment, a reset button 801 and a default setting button 802 are UI corresponding to the photoacoustic wave correction unit 110A in addition to the correction unit 303.

  When the default setting button 802 is pressed, a default setting button event is notified to the control processor 109. The control processor 109 that has received the notification stores and holds in the storage unit 113 the settings of the correction control points 304A to 304G that have been set up until the time of pressing.

  Reference numeral 811 is a reset button for the correction value of the ultrasonic image, and reference numeral 812 is a setting button for updating the default correction value for the ultrasonic image held in the storage unit 113. In the present embodiment, a reset button 811 and a default setting button 812 are UIs corresponding to the ultrasonic correction unit 110B in addition to the correction unit 307.

Next, a subject information correction method according to this embodiment will be described with reference to FIG. FIG. 9A shows the state of the correction value control point as a result of the user's free operation. FIG. 9B and FIG. 9C show the results of applying the correction method according to this embodiment, respectively. Note that the correction means in the first embodiment is provided as a UI displayed on the display unit 112. However, the application of the present invention is not limited to the configuration based on the software UI, and the function may be provided by hardware such as a button.

Reference numeral 903 indicates a state in which the correction control points 904A to 904G are arranged in accordance with the operation as a result of the user operating the photoacoustic wave image correction unit 303.
When the user presses the reset button 801 from this state, a reset button event is notified to the control processor 109. Upon receiving the notification, the control processor 109 reads the correction default value stored in the storage unit 113 and reflects it in the correction unit 303.

  FIG. 9B shows a state (914A to 914G) in which all correction control points are uniformly set to intermediate values as a result of pressing the reset button 801. This is, for example, a state where the device has been reset to the factory settings.

  FIG. 9C shows a state (924 </ b> A to 924 </ b> G) in which the correction control point is set to the correction default value at the time when the correction control point was previously updated as a result of pressing the reset button 801.

When the reset button is pressed, the correction control point moves to generate a value change event, and the flowchart of the object information correction in the first embodiment (FIG. 5) and the flow of object information acquisition in the third embodiment ( The correction can be reflected according to FIG.
The user can apply correction by the reset button 811 to the ultrasonic image by performing the same operation using the ultrasonic correction unit 307 and the reset button 811.

  In the object information acquiring apparatus having the above configuration, the photoacoustic wave image and the ultrasonic image are initially set, that is, reset at the same time after initial correction or after the user operates each correction control point. be able to. Thereby, the complexity of the user operation can be eliminated.

<Embodiment 5>
The object of the present invention can also be achieved by the following means. That is, a storage medium storing software program codes for realizing the functions of the above-described embodiments is supplied to a system or apparatus. Then, the computer (CPU or the like) of the system or apparatus reads and executes the program code stored in the storage medium. In this case, the program code itself read from the storage medium realizes the functions of the above-described embodiment, and the storage medium storing the program code constitutes the present invention.

  Further, by executing the program code read by the computer, an operating system (OS) or the like running on the computer performs part or all of the actual processing based on the instruction of the program code. Needless to say, the process includes the case where the functions of the above-described embodiments are realized.

Furthermore, it is assumed that the program code read from the storage medium is written in a memory provided in a function expansion card inserted into the computer or a function expansion unit connected to the computer. After that, based on the instruction of the program code, the CPU included in the function expansion card or function expansion unit performs part or all of the actual processing, and the function of the above-described embodiment is realized by the processing. Needless to say.
When the present invention is applied to the storage medium, the storage medium stores program codes corresponding to the flowcharts described above.

  A person skilled in the art can easily configure a new system by appropriately combining various technologies in the above embodiments, and thus a system based on such various combinations is also within the scope of the present invention. Belongs to.

  102: probe, 106: photoacoustic wave signal processing unit, 107: ultrasonic transmission control unit, 108: ultrasonic signal processing unit, 109: control processor, 110A: photoacoustic wave correction unit, 110B: ultrasonic correction unit 111: Image composition unit 112: Display unit

Claims (11)

With a probe,
A first image is generated using a photoacoustic wave generated from a subject irradiated with light and received by the probe, and the probe is transmitted to the subject and reflected by the subject. Signal processing means for generating a second image using the received ultrasonic waves;
Display means for displaying the first image and the second image;
First correction means for correcting the luminance of the first image according to the distance from the probe;
Second correction means for correcting the brightness of the second image according to the distance from the probe independently of the first correction means;
A subject information acquisition apparatus characterized by comprising: The object information acquiring apparatus according to claim 1, wherein the display unit superimposes and displays the first image and the second image. The object information acquiring apparatus according to claim 1, wherein the display unit displays the first image and the second image side by side. The first correction unit and the second correction unit are operations for a user to operate the correction value based on an image indicating a correction value for each distance from the probe displayed on the display unit. The object information acquiring apparatus according to claim 1, further comprising: means. 5. The subject information according to claim 4, wherein the display unit displays an image indicating a correction value for each distance from the probe side by side on the first image and the second image. Acquisition device. For at least one of the first image and the second image, further comprising a luminance distribution calculating means for obtaining a luminance distribution for each distance from the probe,
The first correction unit performs correction based on the first luminance distribution when the first luminance distribution indicating the luminance distribution of the first image is obtained by the luminance distribution calculation unit;
The second correcting unit performs correction based on the second luminance distribution when the second luminance distribution indicating the luminance distribution of the second image is obtained by the luminance distribution calculating unit. The object information acquiring apparatus according to claim 1, wherein the object information acquiring apparatus is one of the following. When the first luminance distribution is obtained by the luminance distribution calculating unit, the first correcting unit determines a first reference which is a luminance included in the first luminance distribution, and Correcting the brightness of the image based on the first criterion,
When the second luminance distribution is obtained by the luminance distribution calculating unit, the second correction unit determines a second reference that is a luminance included in the second luminance distribution, and The object information acquiring apparatus according to claim 6, wherein the luminance of the image is corrected based on the second reference. The signal processing means includes a first electrical signal obtained by the probe receiving the photoacoustic wave, and a second electrical signal obtained by the probe receiving the ultrasonic wave. Amplifying
The first correction means controls the amplification gain of the first electric signal according to the time from when the photoacoustic wave is generated until it reaches the probe,
The second correction means controls the amplification gain of the second electric signal according to the time from when the ultrasonic wave is reflected until it reaches the probe. 8. The object information acquiring apparatus according to any one of items 7 to 7. The first correction unit is configured to reduce the first electrical signal according to an attenuation characteristic of the light irradiated on the object in the object and an attenuation characteristic of a photoacoustic wave generated in the object. The object information acquiring apparatus according to claim 8, wherein an amplification gain is controlled. 10. The subject according to claim 8, wherein the second correction unit controls an amplification gain of the second electric signal in accordance with an attenuation characteristic of an ultrasonic wave reflected in the subject. Information acquisition device. A method for controlling an object information acquiring apparatus having a probe, signal processing means, display means, first correction means and second correction means,
The probe receives a photoacoustic wave generated from a subject irradiated with light; and
The signal processing means generating a first image using the photoacoustic wave;
The probe receives ultrasonic waves transmitted to the subject and reflected by the subject; and
The signal processing means generating a second image using the ultrasound; and
The display means displaying the first image and the second image;
The first correcting means correcting the luminance of the first image according to the distance from the probe;
A second step in which the second correction means corrects the luminance of the second image according to the distance from the probe independently of the first correction means;
A method for controlling a subject information acquiring apparatus, comprising:

Images