阅读说明：本技术 图像处理装置、图像处理方法和程序 (Image processing apparatus, image processing method, and program ) 是由 佐佐木翔也 长永兼一 梶田大树 今西宣晶 相磯贞和 于 2019-03-29 设计创作，主要内容包括：一种图像处理装置,具有：光谱图像获取部件,获取光谱图像,该光谱图像是基于通过对已注入有造影剂的被测体照射具有多个不同波长的光而生成的光声波的、使用与所述多个不同波长对应的光声信号生成的图像；造影剂信息获取部件,获取关于造影剂的信息；区域确定部件,基于关于造影剂的信息来确定光谱图像中的与造影剂对应的区域；以及显示控制部件,显示光谱图像,使得能够区分与造影剂对应的区域和除所述区域以外的区域。(An image processing apparatus has: a spectral image acquisition unit that acquires a spectral image that is an image generated using photoacoustic signals corresponding to a plurality of different wavelengths based on photoacoustic waves generated by irradiating a subject into which a contrast agent has been injected with light having the plurality of different wavelengths; a contrast agent information acquisition section that acquires information on a contrast agent; a region determining section that determines a region corresponding to the contrast agent in the spectral image based on the information on the contrast agent; and a display control section that displays the spectral image so that a region corresponding to the contrast agent and a region other than the region can be distinguished.)

1. An image processing apparatus characterized by comprising:

a spectral image acquisition unit that acquires a spectral image that is an image generated using photoacoustic signals corresponding to a plurality of different wavelengths based on photoacoustic waves generated by irradiating a subject into which a contrast agent has been injected with light having the plurality of different wavelengths;

a contrast agent information acquisition section that acquires information on the contrast agent;

a region determination section that determines a region in the spectral image corresponding to the contrast agent based on the information on the contrast agent; and

a display control unit that displays the spectral image so that a region corresponding to the contrast agent and a region other than the region corresponding to the contrast agent can be distinguished.

2. The image processing apparatus according to claim 1,

the region determining part

Determining a numerical range of image values of the spectral image based on the information about the contrast agent, and

determining a region of the spectral image having image values included in the numerical range as a region corresponding to the contrast agent.

3. The image processing apparatus according to claim 1,

the region determination section determines a numerical range of image values of the spectral image to which a color is to be assigned based on information on the contrast agent, and

the display control section assigns colors to image values of the spectral image included in the numerical range and displays the spectral image.

4. The image processing apparatus according to claim 2 or 3,

the sign of the image value of the region corresponding to the contrast agent is opposite to the sign of the image value of the region other than the region corresponding to the contrast agent.

5. The image processing apparatus according to any one of claims 1 to 4,

the region determining section determines a region in the spectral image corresponding to the contrast agent based on the information on the contrast agent and the information of the plurality of wavelengths.

6. An image processing apparatus characterized by comprising:

a spectral image acquisition unit that acquires a spectral image based on photoacoustic waves generated by irradiating a subject into which a contrast agent has been injected with light having a plurality of different wavelengths;

a contrast agent information acquisition section that acquires information on the contrast agent; and

a display control section that assigns colors to image values of the spectral image based on the information on the contrast agent, and displays the spectral image.

7. The image processing apparatus according to claim 6,

the display control means also assigns a color to a negative image value of the spectral image and displays the spectral image.

8. The image processing apparatus according to claim 6 or 7,

the display control means further assigns colors to the image values of the spectral image based on the information on the contrast agent and the information of the plurality of wavelengths, and displays the spectral image.

9. The image processing apparatus according to any one of claims 1 to 8,

the display control part

Displaying a colorimetric scale representing a relationship between an image value of the spectral image and a display color, and

displaying the colorimetric scale so that a display color corresponding to the contrast agent can be recognized.

10. The image processing apparatus according to any one of claims 1 to 9, further comprising:

a photoacoustic image acquiring section that acquires a plurality of photoacoustic images corresponding to the plurality of wavelengths, respectively, the plurality of photoacoustic images being generated based on a photoacoustic wave generated by irradiating a subject into which a contrast agent has been injected with light having the plurality of wavelengths, wherein,

the display control part

Determining the brightness of the spectral image based on an image value of one of the plurality of photoacoustic images, and

a conversion table for converting the image value of the photoacoustic image into luminance is determined based on the image value of the spectral image.

11. The image processing apparatus according to any one of claims 1 to 10,

the contrast agent information acquisition means acquires information on the contrast agent from the supplemental information associated with the spectral image.

12. The image processing apparatus according to any one of claims 1 to 11,

the information on the contrast agent is information on the type or concentration of the contrast agent.

13. The image processing apparatus according to any one of claims 1 to 12, further comprising:

a photoacoustic image acquiring section that acquires a first photoacoustic image based on a photoacoustic wave generated according to irradiation of light having a first wavelength and a second photoacoustic image based on a photoacoustic wave generated according to irradiation of light having a second wavelength, wherein,

the spectral image acquisition means generates an image based on a ratio of the first photoacoustic image to the second photoacoustic image as the spectral image.

14. The image processing apparatus according to any one of claims 1 to 12,

based on a wavelength λ having a first wavelength₁Is measured by a photoacoustic wave generated by the irradiation of light of I^λ ₁(r) based on having a second wavelength λ₂Is measured by a photoacoustic wave generated by the irradiation of light of I^λ ₂(r) and a first wavelength λ₁The corresponding deoxyhemoglobin has a molar absorption coefficient of ε_Hb ^λ ₁And a second wavelength lambda₂The corresponding deoxyhemoglobin has a molar absorption coefficient of ε_Hb ^λ ₂And a first wavelength lambda₁The corresponding oxyhemoglobin has a molar absorption coefficient of ε_HbO ^λ ₁And a second wavelength lambda₂The corresponding oxyhemoglobin has a molar absorption coefficient of ε_HbO ^λ ₂And r is the position of the sensor,

the spectral image acquisition section generates a calculated value is (r) of a spectral image according to the following formula.

[ mathematical expression 1]

15. The image processing apparatus according to claim 14,

the measurement is the absorption coefficient or the initial sound pressure.

16. The image processing apparatus according to any one of claims 1 to 15,

the contrast agent is ICG having a concentration of at least 2.5mg/mL and no more than 10.0 mg/mL.

17. The image processing apparatus according to any one of claims 1 to 16,

the contrast agent information acquisition section is configured to acquire information representing a concentration of the contrast agent as information on the contrast agent based on an instruction from a user, and

in a case where information indicating that the type of the contrast agent is ICG is acquired as the information on the contrast agent, an instruction from the user indicating an ICG concentration of less than 2.5mg/mL or more than 10.0mg/mL is not received.

18. The image processing apparatus according to claim 16 or 17,

the plurality of wavelengths includes 797nm as the first wavelength and 835nm as the second wavelength.

19. The image processing apparatus according to any one of claims 1 to 18,

the display control section displays a plurality of spectral images generated in time series as a moving image.

20. The image processing apparatus according to claim 19,

the display control means may be capable of displaying the moving image in a fast-forward manner.

21. The image processing apparatus according to claim 19 or 20,

the display control means can repeatedly display the moving image.

22. An image processing method, comprising:

acquiring a spectral image which is an image generated using photoacoustic signals corresponding to a plurality of different wavelengths based on photoacoustic waves generated by irradiating a subject into which a contrast agent has been injected with light having the plurality of different wavelengths;

acquiring information about the contrast agent;

determining a region in the spectral image corresponding to the contrast agent based on the information about the contrast agent; and

displaying the spectral image so that a region corresponding to the contrast agent and a region other than the region corresponding to the contrast agent can be distinguished.

23. An image processing method, comprising:

acquiring a spectral image which is an image generated using photoacoustic signals corresponding to a plurality of different wavelengths based on photoacoustic waves generated by irradiating a subject into which a contrast agent has been injected with light having the plurality of different wavelengths;

acquiring information about the contrast agent; and

assigning colors to image values of the spectral image based on the information about the contrast agent, and displaying the spectral image.

24. The image processing method according to claim 22 or 23,

the contrast agent is ICG and the plurality of wavelengths includes 797nm as a first wavelength and 835nm as a second wavelength.

25. A program for causing a computer to execute the image processing method according to any one of claims 22 to 24.

Technical Field

The present invention relates to image processing for images generated by photoacoustic imaging.

Background

In the examination of blood vessels, lymphatic vessels, and the like, photoacoustic imaging (also referred to as "optical ultrasound imaging") using a contrast agent is known. Patent document 1 discloses a photoacoustic image generating apparatus that uses a contrast agent for contrasting lymph nodes, lymphatic vessels, and the like as an evaluation target and projects light having a wavelength that is absorbed by the contrast agent to generate photoacoustic waves.

CITATION LIST

Patent document

Patent document 1: international publication No. WO 2017/002337

Disclosure of Invention

Technical problem

However, in the photoacoustic imaging disclosed in patent document 1, there are cases where it is difficult to find out the structure of a contrast object in a subject (for example, traveling in a blood vessel, a lymphatic vessel, or the like).

Therefore, an object of the present invention is to provide an image processing apparatus that generates an image in which the structure of a contrast object is easily ascertained by photoacoustic imaging.

Solution to the problem

An image processing apparatus according to an aspect of the present invention includes: a spectral image acquisition unit that acquires a spectral image that is an image generated using photoacoustic signals corresponding to a plurality of different wavelengths based on photoacoustic waves generated by irradiating a subject into which a contrast agent has been injected with light having the plurality of different wavelengths; a contrast agent information acquisition section that acquires information on a contrast agent; a region determining section that determines a region corresponding to the contrast agent in the spectral image based on the information on the contrast agent; and a display control section that displays the spectral image so that a region corresponding to the contrast agent and a region other than the region corresponding to the contrast agent can be distinguished.

Advantageous effects of the invention

According to the present invention, it is possible to provide an image processing apparatus that generates an image in which the structure of a contrast object is easily ascertained by photoacoustic imaging.

Drawings

FIG. 1 is a block diagram of a system according to an embodiment of the invention.

Fig. 2 is a block diagram illustrating a specific example of an image processing apparatus and peripheral components thereof according to an embodiment of the present invention.

Fig. 3 is a detailed block diagram of a photoacoustic apparatus according to an embodiment of the present invention.

FIG. 4 is a schematic view of a probe according to an embodiment of the invention.

Fig. 5 is a flowchart of an image processing method according to an embodiment of the present invention.

Fig. 6 is a graph showing an absorption coefficient spectrum when the ICG concentration has changed.

Fig. 7A to 7D are contour plots of calculated values of formula (1) corresponding to the contrast agent when the wavelength combination has changed.

Fig. 8 is a line graph showing the calculated value of formula (1) corresponding to the contrast agent when the ICG concentration has changed.

Fig. 9 is a graph showing molar absorption coefficient spectra of oxyhemoglobin and deoxyhemoglobin.

Fig. 10 is a diagram illustrating a GUI according to an embodiment of the present invention.

Fig. 11A and 11B are spectral images of the right forearm extension side when the ICG concentration has changed.

Fig. 12A and 12B are spectral images of the left forearm extension side when the ICG concentration has changed.

Fig. 13A and 13B are spectral images of the inner right calf and the inner left calf when the ICG concentration has changed.

Detailed Description

Suitable embodiments of the present invention will be described hereinafter with reference to the accompanying drawings. However, the size, material, shape, relative arrangement, and the like of the components described below may be appropriately changed according to the configuration of the apparatus to which the present invention is applied and various conditions. Accordingly, the scope of the invention is not limited by the following description.

The photoacoustic image acquired by the system according to the present invention reflects the amount of absorption and the rate of absorption of light energy. The photoacoustic image is an image representing the spatial distribution of at least one piece of measured body information including the generated sound pressure (initial sound pressure) of the photoacoustic wave, the light absorption energy density, the light absorption coefficient, and the like. The photoacoustic image may be an image representing a two-dimensional spatial distribution, or an image (volume data) representing a three-dimensional spatial distribution. The system according to the present embodiment generates a photoacoustic image by imaging a subject injected with a contrast agent. In addition, in order to find the three-dimensional structure of the contrast object, the photoacoustic image may be an image representing a two-dimensional spatial distribution in the depth direction from the surface of the subject or an image representing a three-dimensional spatial distribution.

Further, the system according to the present invention can generate a spectral image of the subject using a plurality of photoacoustic images corresponding to a plurality of wavelengths. The spectral image of the present invention is an image generated using photoacoustic signals corresponding to a plurality of wavelengths based on photoacoustic waves generated by irradiating a subject with light having a plurality of different wavelengths.

In addition, the spectral image may be an image representing the concentration of a specific substance in the subject, the image being generated using photoacoustic signals corresponding to a plurality of wavelengths. When the light absorption coefficient spectrum of the contrast agent to be used is different from the light absorption coefficient spectrum of the specific substance, the image value of the contrast agent in the spectral image is different from the image value of the specific substance in the spectral image. Therefore, a region of the contrast agent can be distinguished from a region of the specific substance from the image value of the spectral image. In addition, as the specific substance, a substance constituting the subject, such as hemoglobin, glucose, collagen, melanin, fat, or water, is conceivable. In this case, it is necessary to select a contrast agent having a light absorption spectrum different from the light absorption coefficient spectrum of the specific substance. Further, the spectral image may be calculated by different calculation methods according to the type of the specific substance.

In the embodiment to be described below, an image calculated using the oxygen saturation calculation formula (1) is described as a spectral image. The inventors found that, when substituting the measured value i (r) of photoacoustic signals acquired using a contrast agent whose wavelength dependence of the optical absorption coefficient tends to be different from that of oxyhemoglobin and deoxyhemoglobin into formula (1) that calculates the oxygen saturation level of hemoglobin in blood (which may be an index having a correlation with the oxygen saturation level) based on photoacoustic signals corresponding to a plurality of wavelengths, the calculated value is (r) that deviates greatly from the numerical range taken from the oxygen saturation level of hemoglobin is obtained. Therefore, if a spectral image is generated using this calculated value is (r) as an image value, it is easy to separate (distinguish) a hemoglobin region (blood vessel region) in the subject from a contrast agent-existing region (for example, a lymphatic vessel region if a contrast agent is injected into the lymphatic vessel) on the image.

[ mathematical expression 1]

Here, I^λ ₁(r) is based on having a first wavelength λ₁Measured value of photoacoustic wave generated by irradiation of light of (1)^λ ₂(r) is based on having a second wavelength λ₂Is measured by the photoacoustic wave generated by the irradiation of light. Epsilon_Hb ^λ ₁Is related to the first wavelength lambda₁Molar absorption coefficient of the corresponding deoxyhemoglobin mm^-1mol^-1]，ε_Hb ^λ ₂Is related to a second wavelength lambda₂Molar absorption coefficient of the corresponding deoxyhemoglobin mm^-1mol^-1]。ε_HbO ^λ ₁Is related to the first wavelength lambda₁Molar absorption coefficient of the corresponding oxyhemoglobin [ mm ]^-1mol^-1]，ε_HbO ^λ ₂Is related to a second wavelength lambda₂Molar absorption coefficient of the corresponding oxyhemoglobin [ mm ]^-1mol^-1]. r is the position. In addition, as the measured value I^λ ₁(r) and I^λ ₂(r), the absorption coefficient μ can be used_a ^λ ₁(r) and μ_a ^λ ₂(r) alternatively, an initial sound pressure P may be used₀ ^λ ₁(r) and P₀ ^λ ₂(r)。

When the measurement value based on the photoacoustic wave generated from the hemoglobin-existing region (blood vessel region) is substituted into formula (1), the oxygen saturation level of hemoglobin (or an index having a correlation with the oxygen saturation level) is acquired as the calculation value is (r). On the other hand, in the subject injected with the contrast agent, when the measurement value based on the acoustic wave generated from the contrast agent existing region (e.g., lymphatic vessel region) is substituted into the formula (1), the pseudo concentration distribution of the contrast agent is acquired as the calculation value is (r). In addition, when calculating the concentration distribution of the contrast agent, the value of the molar absorption coefficient of hemoglobin may be used as it is in formula (1). The spectral image is (r) acquired in this way becomes an image depicted in a state where both the hemoglobin-existing region (blood vessel) and the contrast agent-existing region (e.g., lymphatic vessel) in the subject can be separated (distinguished) from each other.

In addition, although the image value of the spectral image is calculated using the formula (1) of calculating the oxygen saturation in the present embodiment, a calculation method other than the formula (1) may be used when an index other than the oxygen saturation is calculated as the image value of the spectral image. Since a known index and an index calculation method can be used as the index and its calculation method, a detailed description thereof is omitted here.

Furthermore, the system according to the invention may use the representation based on having the first wavelength λ₁The first photoacoustic image and the base of the photoacoustic wave generated by the irradiation of lightAt a second wavelength λ₂The ratio of the second photoacoustic image of the photoacoustic wave generated by the irradiation of light of (a) is taken as a spectral image. That is, an image based on a ratio of the first photoacoustic image to the second photoacoustic image, where the first photoacoustic image is based on the photoacoustic image having the first wavelength λ, may be used as the spectral image₁And the second photoacoustic image is based on a photoacoustic wave generated according to the light having the second wavelength λ₂The light of (2) generates a photoacoustic wave. In addition, the image generated according to the deformation formula of formula (1) can also be represented by the ratio of the first photoacoustic image to the second photoacoustic image, and thus can be said to be an image (spectral image) based on the ratio of the first photoacoustic image to the second photoacoustic image.

In addition, in order to find the three-dimensional structure of the contrast object, the spectral image may be an image representing a two-dimensional spatial distribution in the depth direction from the surface of the subject or an image representing a three-dimensional spatial distribution.

Hereinafter, the configuration of the system of the present embodiment and the image processing method will be described.

A system according to the present embodiment will be described using fig. 1. Fig. 1 is a block diagram illustrating the configuration of a system according to the present embodiment. The system according to the present embodiment includes a photoacoustic apparatus 1100, a storage apparatus 1200, an image processing apparatus 1300, a display apparatus 1400, and an input apparatus 1500. Transmission and reception of data between the devices may be performed in a wired or wireless manner.

The photoacoustic apparatus 1100 generates a photoacoustic image by imaging a subject into which a contrast agent has been injected, and outputs the photoacoustic image to the storage apparatus 1200. The photoacoustic apparatus 1100 is an apparatus that generates information of characteristic values corresponding to a plurality of positions in a subject using a reception signal acquired by receiving a photoacoustic wave generated from irradiation of light. That is, the photoacoustic apparatus 1100 is an apparatus that generates a spatial distribution of characteristic value information derived from a photoacoustic wave as medical image data (photoacoustic image).

The storage device 1200 may be a storage medium such as a Read Only Memory (ROM), a magnetic disk, or a flash memory. Further, the storage 1200 may be a storage server via a network such as Picture Archiving and Communication System (PACS).

The image processing apparatus 1300 is an apparatus that processes information such as the photoacoustic image and the supplementary information of the photoacoustic image stored in the storage apparatus 1200.

A unit that performs an arithmetic function of the image processing apparatus 1300 may be constituted by a processor such as a CPU or a Graphics Processing Unit (GPU) and an arithmetic circuit such as a Field Programmable Gate Array (FPGA). These units may be constituted not only by a single processor and a single arithmetic circuit, but also by a plurality of processors and a plurality of arithmetic circuits.

A unit performing a storage function of the image processing apparatus 1300 may be configured as a non-transitory storage medium such as a Read Only Memory (ROM), a magnetic disk, or a flash memory. In addition, the unit performing the storage function may be a volatile medium such as a Random Access Memory (RAM). In addition, the storage medium storing the program is a non-transitory storage medium. In addition, a unit performing a storage function may be configured not only as a single storage medium but also as a plurality of storage media.

A unit that performs a control function of the image processing apparatus 1300 is configured as an arithmetic element such as a CPU. The unit performing the control function controls the operation of each component of the system. The unit performing the control function may receive an instruction signal of various operations such as start of measurement from the input unit and control each component of the system. Further, the unit performing the control function may read a program code stored in the computer 150 and control the operation of each component of the system.

The display device 1400 is a display such as a liquid crystal display or an organic Electroluminescent (EL) device. In addition, the display apparatus 1400 may display a GUI for operating an image or an apparatus.

As the input device 1500, an operation console that can be operated by a user and is configured by a mouse, a keyboard, and the like can be used. Further, the display apparatus 1400 may be configured as a touch panel, and the display apparatus 1400 may serve as the input apparatus 1500.

Fig. 2 illustrates a specific configuration example of an image processing apparatus 1300 according to the present embodiment. The image processing apparatus 1300 according to the present embodiment includes a CPU 1310, a GPU 1320, a RAM 1330, a ROM 1340, and an external storage device 1350. Further, a liquid crystal display 1410 as the display apparatus 1400, and a mouse 1510 and a keyboard 1520 as the input apparatus 1500 are connected to the image processing apparatus 1300. In addition, the image processing apparatus 1300 is connected to an image server 1210 as a storage apparatus 1200 such as a Picture Archiving and Communication System (PACS). Accordingly, the image data may be stored in the image server 1210, or the image data in the image server 1210 may be displayed on the liquid crystal display 1410.

Next, a configuration example of the devices included in the system according to the present embodiment will be described. Fig. 3 is a schematic block diagram of devices included in the system according to the present embodiment.

The photoacoustic apparatus 1100 according to the present embodiment includes the driving unit 130, the signal collecting unit 140, the computer 150, the probe 180, and the injecting unit 190. The probe 180 includes a light irradiation unit 110 and a receiving unit 120. Fig. 4 is a schematic diagram of a probe 180 according to the present embodiment. The measurement object is the subject 100 into which the contrast agent is injected by the injection unit 190. The driving unit 130 drives the light irradiation unit 110 and the receiving unit 120 to perform mechanical scanning. When the light irradiation unit 110 irradiates light to the subject 100, an acoustic wave is generated in the subject 100. The acoustic wave generated from the photoacoustic effect caused by light is also referred to as a photoacoustic wave. The receiving unit 120 outputs an electric signal (photoacoustic signal) as an analog signal when receiving the photoacoustic wave.

The signal collection unit 140 converts the analog signal output from the reception unit 120 into a digital signal and outputs the digital signal to the computer 150. The computer 150 stores the digital signal output from the signal collection unit 140 as signal data derived from the photoacoustic wave.

The computer 150 generates a photoacoustic image by performing signal processing on the stored digital signal. Further, the computer 150 performs image processing on the obtained photoacoustic image, and then outputs the photoacoustic image to the display unit 160. The display unit 160 displays an image based on the photoacoustic image. The display image is stored in a memory in the computer 150 or a storage device 1200 such as a data management system connected to a modality (modality) through a network based on a storage instruction from a user or the computer 150.

Further, the computer 150 also performs drive control of components included in the photoacoustic apparatus. Further, the display unit 160 may display a GUI or the like in addition to the image generated by the computer 150. The input unit 170 is configured to allow a user to input information. The user can perform operations such as start or end of measurement and an indication of storage of a generated image using the input unit 170.

Hereinafter, each component of the photoacoustic apparatus 1100 according to the present embodiment will be described in detail.

(light irradiation unit 110)

The light irradiation unit 110 includes a light source 111 that emits light and an optical system 112 that guides the light projected from the light source 111 to the object 100. In addition, the light includes pulsed light such as so-called rectangular wave and triangular wave.

In view of the thermal suppression condition and the stress suppression condition, it is preferable that the pulse width of the light emitted from the light source 111 is not more than 100 ns. In addition, a wavelength in the range of about 400nm to 1600nm may be used as the wavelength of light. When imaging blood vessels at high resolution, wavelengths that absorb more in blood vessels (at least 400nm and no more than 700nm) may be used. When imaging a deep part of a living body, light of a wavelength (at least 700nm and not more than 1100nm) which is generally less absorbed in background tissue (water, fat, and the like) of the living body can be used.

A laser or a light emitting diode may be used as the light source 111. Further, when measurement is performed using light having a plurality of wavelengths, a light source capable of changing the wavelength may be used. In addition, in the case of irradiating a plurality of wavelengths to a subject, a plurality of light sources generating light having different wavelengths may be provided, and light may be alternately irradiated from the respective light sources. In the case where a plurality of light sources are used, the light sources are collectively represented as one light source. As the laser, various lasers such as a solid laser, a gas laser, a dye laser, and a semiconductor laser can be used. For example, a pulsed laser such as a Nd: YAG laser or alexandrite laser (alexandrite laser) can be used as the light source. In addition, a Ti: sa laser or an Optical Parametric Oscillator (OPO) laser using Nd: YAG laser as excitation light may be used as the light source. In addition, a flash lamp or a light emitting diode may be used as the light source 111. In addition, a microwave source may be used as the light source 111.

Optical elements such as lenses, mirrors, and optical fibers may be used for the optical system 112. In the case where a breast or the like is used as the object 100, the light projecting portion of the optical system may be configured as a diffuser or the like that diffuses light to expand the beam diameter of the pulsed light and irradiate the pulsed light. On the other hand, in the photoacoustic microscope, the light projecting portion of the optical system 112 may be configured as a lens or the like and focus and irradiate a light beam to improve resolution.

In addition, the light irradiation unit 110 may directly irradiate the light to the object 100 from the light source 111 without including the optical system 112.

(receiving unit 120)

The receiving unit 120 includes a transducer 121 outputting an electrical signal upon receiving an acoustic wave, and a support 122 supporting the transducer 121. Further, the transducer 121 may be a transmitting part that transmits an acoustic wave. The transducer as the receiving means and the transducer as the transmitting means may be a single (common) transducer or separate components.

As a member constituting the transducer 121, a piezoelectric ceramic material typified by lead zirconate titanate (PZT), a polymer piezoelectric film material typified by polyvinylidene fluoride (PVDF), or the like can be used. Further, an element other than the piezoelectric element may be used. For example, a transducer using a Capacitive Micromachined Ultrasonic Transducer (CMUT) or the like may be used. In addition, any transducer may be used as long as it can output an electric signal upon receiving an acoustic wave. Furthermore, the signals acquired by the transducers are time-resolved signals. That is, the amplitude of the signal acquired by the transducer represents a value based on the sound pressure received by the transducer at each instant of time (e.g., a value proportional to the sound pressure).

Frequency components constituting the photoacoustic wave are typically 100KHz to 100MHz, and a transducer capable of detecting these frequencies may be employed as the transducer 121.

The support 122 may be formed of a metal material having high mechanical strength. A mirror finishing or a process for light scattering may be performed on the surface of the subject 100 side of the support 122 so that a large amount of irradiation light is input to the subject. In the present embodiment, the support 122 has a hemispherical shell shape and is configured to be able to support the plurality of transducers 121 on the hemispherical shell. In this case, the orientation axes of the transducers 121 disposed in the support 122 converge near the center of curvature of the hemisphere. Then, when imaging is performed using signals output from the plurality of transducers 121, the image quality near the center of curvature improves. In addition, the support 122 may take any configuration as long as it can support the transducer 121. The support 122 may be configured such that multiple transducers are arranged side-by-side within a plane or curved surface referred to as a 1D array, a 1.5D array, a 1.75D array, or a 2D array. The plurality of transducers 121 correspond to the plurality of receiving parts.

In addition, the support 122 may serve as a container for storing the acoustic matching material. That is, the support 122 may serve as a container for deploying acoustically matching material between the transducer 121 and the subject 100.

Further, the receiving unit 120 may include an amplifier that amplifies the timing analog signal output from the transducer 121. In addition, the receiving unit 120 may include an a/D converter that converts the time-series analog signal output from the transducer 121 into a time-series digital signal. That is, the receiving unit 120 may include a signal collecting unit 140 described later.

The space between the receiving unit 120 and the object 100 is filled with a medium capable of propagating photoacoustic waves. As the medium, a material that can propagate an acoustic wave so that acoustic characteristics at an interface between the subject 100 and the transducer 121 can be matched and that has a photoacoustic wave transmittance as high as possible is employed. For example, water, ultrasonic gel, or the like may be used as the medium.

Fig. 4 shows a side view of the probe 180. The probe 180 according to the present embodiment includes a receiving unit 120 in which a plurality of transducers 121 are three-dimensionally arranged in a hemispherical support 122 having an opening. Further, the light projection unit of the optical system 112 is disposed at the bottom of the support 122.

In the present embodiment, as shown in fig. 4, when the subject 100 is in contact with the holder 200, the shape of the subject 100 is held.

The space between the receiving unit 120 and the holder 200 is filled with a medium capable of propagating photoacoustic waves. As the medium, a material that can propagate an acoustic wave so that acoustic characteristics at an interface between the subject 100 and the transducer 121 can be matched and that has a photoacoustic wave transmittance as high as possible is employed. For example, water, ultrasonic gel, or the like may be used as the medium.

The holder 200 as a holding member is used to hold the shape of the object 100 during measurement. By holding the subject 100 with the holder 200, it is possible to suppress movement of the subject 100 and hold the position of the subject 100 within the holder 200. As a material of the holder 200, a resin material such as polycarbonate, polyethylene, or polyethylene terephthalate may be used.

The holder 200 is attached to the mounting portion 201. The mounting portion 201 may be configured so that a plurality of types of holders 200 can be replaced in accordance with the size of the subject. For example, the mounting portion 201 may be configured to enable replacement of holders having different radii of curvature and different centers of curvature.

(drive unit 130)

The driving unit 130 is a portion that changes the relative position of the subject 100 and the receiving unit 120. The driving unit 130 includes a motor such as a stepping motor that generates a driving force, a driving mechanism that transmits the driving force, and a position sensor that detects position information of the receiving unit 120. As the drive mechanism, a screw mechanism, a link mechanism, a gear mechanism, a hydraulic mechanism, or the like can be used. Further, as the position sensor, a potentiometer using an encoder, a variable resistor, a linear scale, a magnetic sensor, an infrared sensor, an ultrasonic sensor, or the like can be used.

In addition, the driving unit 130 is not limited to changing the relative position of the subject 100 and the receiving unit 120 in the XY direction (two-dimensionally), but may be changed one-dimensionally or three-dimensionally.

In addition, the driving unit 130 may fix the receiving unit 120 and move the subject 100 as long as it can change the relative position of the subject 100 and the receiving unit 120. When the subject 100 is moved, an arrangement in which the subject 100 is moved by moving a holder that holds the subject 100, and the like is conceivable. In addition, both the subject 100 and the receiving unit 120 can be moved.

The driving unit 130 may move the relative position continuously or in a step-and-repeat manner. The driving unit 130 may be a motorized stage (stage) or a manual stage that enables movement along a programmed trajectory.

Further, although the driving unit 130 performs scanning by simultaneously driving the light irradiation unit 110 and the receiving unit 120 in the present embodiment, the driving unit 130 may drive only the light irradiation unit 110 or only the receiving unit 120.

In addition, in the case where the probe 180 is of a handheld type equipped with a grip portion, the photoacoustic apparatus 1100 may not include the driving unit 130.

(Signal collecting Unit 140)

The signal collection unit 140 includes an amplifier that amplifies an electric signal, which is an analog signal output from the transducer 121, and an a/D converter that converts the analog signal output from the amplifier into a digital signal. The digital signal output from the signal collection unit 140 is stored in the computer 150. The signal collection unit 140 is also referred to as a Data Acquisition System (DAS). The electric signal in this specification is a concept including both an analog signal and a digital signal. In addition, a light detection sensor such as a photodiode may detect light projection from the light irradiation unit 110, and the signal collection unit 140 may start the above-described process by synchronizing the detection result with the trigger.

(computer 150)

The computer 150 as an information processing apparatus is configured similarly to the hardware of the image processing apparatus 1300. That is, a unit performing an arithmetic function of the computer 150 may be constituted by a processor such as a CPU or a Graphic Processing Unit (GPU) and an arithmetic circuit such as a Field Programmable Gate Array (FPGA). These units may be constituted not only by a single processor and a single arithmetic circuit, but also by a plurality of processors and a plurality of arithmetic circuits.

The unit performing a storage function of the computer 150 may be a volatile medium such as a Random Access Memory (RAM). In addition, the storage medium storing the program is a non-transitory storage medium. In addition, a unit performing a storage function of the computer 150 may be configured not only as a single storage medium but also as a plurality of storage media.

A unit that performs a control function of the computer 150 is configured as an arithmetic element such as a CPU. The unit that performs the control function of the computer 150 controls the operation of each component of the photoacoustic apparatus. The unit that performs the control function of the computer 150 can receive an instruction signal of various operations such as start of measurement from the input unit 170 and control each component of the photoacoustic apparatus. Further, the unit performing the control function of the computer 150 may read the program code stored in the unit performing the storage function and control the operation of each component of the photoacoustic apparatus. That is, the computer 150 may function as a control device of the system according to the present embodiment.

In addition, the computer 150 and the image processing apparatus 1300 may be configured as the same hardware. A single piece of hardware may perform the functions of both the computer 150 and the image processing apparatus 1300. That is, the computer 150 may execute the functions of the image processing apparatus 1300. In addition, the image processing apparatus 1300 may execute the function of the computer 150 as an information processing apparatus.

(display unit 160)

The display unit 160 is a display such as a liquid crystal display or an organic Electroluminescent (EL) device. Further, the display unit 160 may display a GUI for operating an image or a device.

In addition, the display unit 160 and the display apparatus 1400 may be the same display. That is, a single display may perform the functions of both the display unit 160 and the display apparatus 1400.

(input unit 170)

As the input unit 170, an operation console constituted by a mouse, a keyboard, and the like that can be operated by a user can be employed. Further, the display unit 160 may be configured as a touch panel, and the display unit 160 may serve as the input unit 170.

In addition, the input unit 170 and the input device 1500 may be the same device. That is, a single device may perform the functions of both the input unit 170 and the input device 1500.

(injection unit 190)

The injection unit 190 is configured to enable injection of a contrast agent into the subject 100 from outside the subject 100. For example, the injection unit 190 may include a contrast medium container and an injection needle that penetrates the subject. However, the injection unit 190 is not limited thereto and can be applied to various types as long as they can inject a contrast agent into the subject 100. In this case, the injection unit 190 may be a known injection system or a syringe, for example. In addition, the computer 150 as the control device can inject the contrast agent into the subject 100 by controlling the operation of the injection unit 190. Further, the user can inject a contrast agent into the subject 100 by operating the injection unit 190.

(test body 100)

Although the subject 100 does not constitute a system, it will be described below. The system according to the present embodiment can be used for the purpose of diagnosis of malignant tumors, vascular diseases, and the like, and process observation of chemotherapy, and the like, in humans or animals. Therefore, as the object 100, a part to be diagnosed, such as a living body, specifically, a breast, various organs, a blood vessel network, a head, a neck, an abdomen, limbs including fingers or toes, or the like of a human body or an animal, is conceivable. For example, if a human body is taken as a measurement object, oxyhemoglobin or deoxyhemoglobin, a blood vessel containing a large amount of these substances, a new blood vessel formed near a tumor, or the like can be used as an object of the light absorber. In addition, plaques of the carotid artery wall and the like can be targeted as light absorbers. In addition, melanin, collagen, lipid, and the like contained in the skin can be used as an object of the light absorber. In addition, a contrast agent injected into the subject 100 may be used as an optical absorber. As a contrast agent for photoacoustic imaging, a dye such as indocyanine green (ICG) or Methylene Blue (MB), a gold particle, a mixture thereof, or an externally introduced substance obtained by integrating or chemically modifying these materials may be employed. In addition, a phantom (phantom) mimicking a living body may be used as the subject 100.

In addition, the components of the photoacoustic apparatus may be configured as separate apparatuses or as an integrated single apparatus. Further, at least some of the components of the photoacoustic apparatus may be configured as a unitary, single apparatus.

In addition, each apparatus constituting the system according to the present embodiment may be configured as separate hardware, or all the apparatuses may be configured as a single hardware. The functions of the system according to the present embodiment may be configured using any hardware.

Next, an image generation method according to the present embodiment will be described using a flowchart shown in fig. 5. In addition, the flowchart shown in fig. 5 includes a procedure representing the operation of the system according to the present embodiment and a procedure representing the operation of a user such as a doctor.

(S100: procedure for obtaining checklist information)

The computer 150 of the photoacoustic apparatus 1100 acquires examination order information transmitted from an in-hospital information system (in-hospital information system) such as a Hospital Information System (HIS) or a Radiology Information System (RIS). The examination order information includes information such as a type of modality used for the examination and a contrast agent used for the examination.

(S200: Process of acquiring information on contrast agent based on user' S instruction or examination order information)

The computer 150 as a contrast agent information acquisition means acquires information on the contrast agent. The user may indicate the type and concentration of contrast agent used for the examination using the input unit 170. In this case, the computer 150 may acquire information about the contrast agent through the input unit 170. Further, in the case where the examination order information acquired in S100 includes information on the contrast agent, the computer 150 may acquire the information on the contrast agent by reading the information on the contrast agent from the examination order information. The computer 150 may acquire information about the contrast agent based on at least one of the indication of the user and the examination order information. For example, as the information on the contrast agent indicating the condition of the contrast agent, the type of the contrast agent, the concentration of the contrast agent, and the like are conceivable.

Fig. 10 illustrates an example of a GUI displayed on the display unit 160. Items 2500 of the GUI display examination order information such as patient ID, examination ID, and imaging date and time. The item 2500 may include a display function of displaying checklist information acquired from an external device such as a HIS or RIS and an input function of enabling a user to input checklist information using the input unit 170. An item 2600 of the GUI displays information about the contrast agent such as the type of the contrast agent and the concentration of the contrast agent. The item 2600 may include a display function of displaying information about a contrast agent acquired from an external device such as a HIS or RIS and an input function of enabling a user to input information about a contrast agent using the input unit 170. In item 2600, information on the contrast agent, such as the type and concentration of the contrast agent, may be input from among a plurality of choices by a method such as a pull-down list (pull-down). In addition, the GUI shown in fig. 10 may be displayed on the display apparatus 1400.

In addition, in a case where the image processing apparatus 1300 has not received an input instruction of information on a contrast agent from a user, information on a contrast agent set as a default value may be acquired from a plurality of pieces of information on a contrast agent. In the case of the present embodiment, a case where ICG is set as a default contrast agent type and 1.0mg/mL is set as a default contrast agent concentration is described. Although the type and concentration of the contrast agent set as default values are displayed in the item 2600 of the GUI in the present embodiment, the information on the contrast agent may not be set as default values. In this case, information on the contrast agent may not be displayed in the item 2600 of the GUI on the initial screen.

(S300: Process of injecting contrast agent)

The injection unit 190 injects a contrast agent into the subject. When the user injects a contrast agent into the subject using the injection unit 190, the user can transmit a signal indicating that the contrast agent has been injected from the input unit 170 to the computer 150 as the control device by operating the input unit 170. Further, the injection unit 190 may transmit a signal indicating that the contrast agent has been injected into the subject 100 to the computer 150. In addition, a contrast medium may be injected into the subject without using the injection unit 190. For example, a contrast agent may be administered into a living body as a subject in such a manner that the living body inhales the sprayed contrast agent.

After the injection of the contrast agent, S400 described later may be performed after the time when the contrast agent is scattered to the contrast object in the subject 100.

(S400: Process of determining wavelength of irradiated light)

The computer 150 as the wavelength determining means determines the wavelength of the irradiated light based on the information on the contrast agent acquired in S200. In the present embodiment, the computer 150 determines a plurality of wavelengths based on information about the contrast agent to generate a spectral image. Hereinafter, a combination of wavelengths for easily identifying a region corresponding to a contrast agent in a spectral image will be described.

In the present embodiment, a case is assumed where an image according to formula (1) is generated as a spectral image in S800 described later. According to the formula (1), for the region of the blood vessel in the spectral image, an image value responsive to the actual oxygen saturation is calculated. However, for regions of contrast agent in the spectral image, the image values vary significantly depending on the wavelength used. Furthermore, for a region of the contrast agent in the spectral image, the image value also changes significantly depending on the absorption coefficient spectrum of the contrast agent. Therefore, the image value of the region of the contrast agent in the spectral image may be a value that cannot be distinguished from the image value of the region of the blood vessel. In addition, in order to find the three-dimensional distribution of the contrast agent, it is preferable that the image value of the region of the contrast agent in the spectral image is a value that can be distinguished from the image value of the region of the blood vessel.

Therefore, the inventors conceived of a method of adaptively changing the wavelength of irradiation light according to the condition of a contrast agent for examination to thereby control the image value of the region of the contrast agent in a spectral image. That is, the inventors devised a method in which the information processing apparatus determines the wavelength of the irradiation light that enables the region of the contrast agent to be distinguished from the region of the blood vessel in the spectral image based on the information about the contrast agent.

Specifically, in the case of generating an image using the formula (1) as a spectral image, the wavelength of the irradiation light can be determined using the fact that the oxygen saturation of the arteriovenous falls within a range of about 60% to 100% expressed in percentage. That is, the computer 150 as the information processing apparatus may determine two wavelengths at which the value of the formula (1) corresponding to the contrast agent in the spectral image becomes less than 60% or more than 100% based on the information on the contrast agent. Further, the computer 150 may determine, based on the information about the contrast agent, two wavelengths at which the sign of the image value of the region corresponding to the contrast agent in the spectral image becomes opposite to the sign of the image value of the other region.

Next, a change in image values corresponding to a contrast agent when the density of the contrast agent, which is information about the contrast agent, has changed will be described. Fig. 6 is a spectral diagram illustrating a change in absorption coefficient spectrum when the concentration of ICG as a contrast agent has changed. FIG. 6 shows spectra in the case where the concentration of ICG was 5.04. mu.g/mL, 50.4. mu.g/mL, 0.5mg/mL, and 1.0mg/mL in this order from the bottom. As shown in fig. 6, it can be understood that the degree of absorption of light increases as the concentration of the contrast agent increases. Further, it is understood that since the ratio of the absorption coefficients corresponding to the two wavelengths changes in response to the concentration of the contrast agent, the image value corresponding to the contrast agent in the spectral image changes in response to the concentration of the contrast agent. When the type of the contrast agent has been changed, the ratio of the absorption coefficients corresponding to the two wavelengths also changes, as is the case when the concentration of the contrast agent has been changed. Therefore, it can be understood that the image value corresponding to the contrast agent in the spectral image also changes in response to the type of the contrast agent.

Here, a spectral image obtained by imaging a living body into which ICG has been injected using a photoacoustic apparatus will be described. Fig. 11A to 13B illustrate spectral images obtained by imaging when ICG is injected while changing the density. In all imaging procedures, 0.1mL of ICG was injected under or within the skin of the hand or foot. ICG injected under or into the skin selectively enters the lymphatic vessels, thus imaging the lumen of the lymphatic vessels. Further, in all imaging operations, imaging was performed within 5 minutes to 60 minutes from the injection of ICG. Further, all the spectral images are spectral images generated from photoacoustic images obtained by irradiating light having a wavelength of 797nm and light having a wavelength of 835nm to a living body.

Fig. 11A illustrates a spectral image of the right forearm extension side when the ICG has not been injected. On the other hand, FIG. 11B illustrates a spectral image on the right forearm extension side when ICG is injected at a concentration of 2.5 mg/mL. Lymphatic vessels are depicted in the areas indicated by dotted lines and arrows in fig. 11B.

FIG. 12A shows a spectral image of the left forearm extension when ICG was injected at a concentration of 1.0 mg/mL. FIG. 12B shows a spectral image of the left forearm extension when ICG is injected at a concentration of 5.0 mg/mL. Lymphatic vessels are depicted in the areas indicated by dotted lines and arrows in fig. 12B.

FIG. 13A illustrates a spectral image of the inside of the right calf when ICG is injected at a concentration of 0.5 mg/mL. FIG. 13B illustrates a spectral image of the inner left calf when ICG was injected at a concentration of 5.0 mg/mL. Lymphatic vessels are depicted in the areas indicated by dotted lines and arrows in fig. 13B.

From the spectral images shown in fig. 11A to 13B, it can be understood that the visibility of lymphatic vessels in the spectral images is improved as the ICG concentration increases. Further, from fig. 11A to 13B, it can be understood that in the case where the concentration of ICG is at least 2.5mg/mL, lymphatic vessels can be satisfactorily depicted. That is, in the case where the concentration of ICG is at least 2.5mg/mL, the lymphatic vessels on the line can be clearly identified visually. Thus, where ICG is used as the contrast agent, its concentration may be at least 2.5 mg/mL. In addition, the concentration of ICG may be more than 5.0mg/mL in view of the dilutability of ICG in a living body. However, when the solubility of indocyanine green injection (Diagnogreen) is considered, it is difficult to melt it in an aqueous solution at a concentration of at least 10.0 mg/mL.

As described above, the concentration of ICG injected into a living body may be at least 2.5mg/mL and not more than 10.0mg/mL, and preferably at least 5.0mg/mL and not more than 10.0 mg/mL.

Accordingly, the computer 150 may be configured to selectively receive an instruction from the user indicating an ICG concentration within the above numerical range in a case where the ICG is input as a contrast agent type in the item 2600 of the GUI shown in fig. 10. That is, in this case, the computer 150 may be configured such that it does not receive an indication from the user that the ICG concentration is not within the above-described numerical range. Thus, the computer 150 may be configured such that the indication from the user indicating that the ICG concentration is less than 2.5mg/mL or greater than 10.0mg/mL is not received if the information indicating that the contrast agent type is ICG is acquired. Further, the computer 150 may be configured such that the instruction from the user indicating that the ICG concentration is less than 5.0mg/mL or greater than 10.0mg/mL is not received if the information indicating that the contrast agent type is ICG is acquired.

The computer 150 may configure the GUI such that the user cannot indicate on the GUI an ICG concentration that does not fall within the above numerical range. That is, the computer 150 may cause the GUI to be displayed such that the user cannot indicate the ICG concentration that does not fall within the above numerical range on the GUI. For example, the computer 150 may cause a drop-down list, by which ICG concentrations within the above numerical range can be selectively indicated, to be displayed on the GUI. The computer 150 may configure the GUI such that ICG concentrations that do not fall within the above numerical range in the drop-down list are displayed as gray and the concentration of gray cannot be selected.

Further, the computer 150 may notify an alarm when the user has indicated on the GUI an ICG concentration that does not fall within the above numerical range. As the notification method, any method such as display of an alarm on the display unit 160, sound, and lighting of a lamp may be employed.

Further, when ICG has been selected as the contrast agent type on the GUI, the computer 150 may cause the display unit 160 to display the above numerical range as the concentration of ICG to be injected into the subject.

In addition, the concentration of the contrast agent injected into the subject is not limited to the numerical range shown here, and an appropriate concentration may be used as appropriate for the purpose. Further, although an example of the case where the contrast agent type is ICG has been described here, the above configuration can be applied to other contrast agents in the same manner.

By configuring the GUI in this manner, the user can be supported to inject an appropriate concentration of contrast agent into the subject depending on the type of contrast agent expected to be injected into the subject.

Next, a change in image values corresponding to the contrast agent in the spectral image when the combination of wavelengths has changed will be described. Fig. 7A to 7D illustrate simulation results of image values (oxygen saturation values) corresponding to a contrast agent in a spectral image in a combination of two wavelengths. The vertical axis and the horizontal axis of fig. 7A to 7D represent the first wavelength and the second wavelength. Contours of image values corresponding to the contrast agent in the spectral images are illustrated in fig. 7A to 7D. FIGS. 7A to 7D are graphs showing image values corresponding to the contrast agent in the spectral images at ICG concentrations of 5.04. mu.g/mL, 50.4. mu.g/mL, 0.5mg/mL, and 1.0mg/mL, respectively. As shown in fig. 7A to 7D, there are cases where the image value corresponding to the contrast agent in the spectral image becomes 60% to 100% depending on the selected wavelength combination. As described above, when such a wavelength combination is selected, it is difficult to distinguish a region of a blood vessel from a region of a contrast agent in a spectral image. Therefore, it is preferable to select a wavelength combination such that the image value corresponding to the contrast agent in the spectral image becomes less than 60% or more than 100% from the wavelength combinations shown in fig. 7A to 7D. Further, it is preferable to select a wavelength combination such that an image value corresponding to the contrast agent in the spectral image becomes a negative value from among the wavelength combinations shown in fig. 7A to 7D.

For example, a case may be envisaged here in which 797nm is selected as the first wavelength and 835nm is selected as the second wavelength. Fig. 8 is a graph showing a relationship between the ICG concentration and an image value (value of formula (1)) corresponding to a contrast agent in a spectral image in the case where 797nm is selected as the first wavelength and 835nm is selected as the second wavelength. According to fig. 8, in the case where 797nm is selected as the first wavelength and 835nm is selected as the second wavelength, the image value corresponding to the contrast agent in the spectral image is a negative value for any concentration in the range of 5.04 μ g/mL to 1.0 mg/mL. Therefore, in the case of generating a spectral image from such a wavelength combination, since the oxygen saturation of the blood vessel is not a negative value in principle, the blood vessel region can be clearly distinguished from the contrast agent region.

In addition, although it has been described that the wavelength is determined based on information on the contrast agent, the absorption coefficient of hemoglobin may be considered in determining the wavelength. Fig. 9 illustrates spectra of the molar absorption coefficient of oxyhemoglobin (dotted line) and the molar absorption coefficient of deoxyhemoglobin (solid line). In the wavelength range shown in fig. 9, the magnitude relationship between the molar absorption coefficient of oxyhemoglobin and the molar absorption coefficient of deoxyhemoglobin is inverted at 797 nm. That is, it can be said that veins are easily recognized at a wavelength shorter than 797nm, and arteries are easily recognized at a wavelength longer than 797 nm. However, in the treatment of lymphedema, lymphatic venous anastomosis (lymphatics-venous anastamosis) which makes a bypass between a lymphatic vessel and a vein is used. For its preoperative examination, it is conceivable to use photoacoustic imaging to image both the vein and the lymphatic vessels that have accumulated contrast agent. In this case, the vein can be imaged more clearly by setting at least one of the plurality of wavelengths to a wavelength shorter than 797 nm. Further, it is advantageous for imaging of veins to set at least one of the plurality of wavelengths to a wavelength at which the molar absorption coefficient of deoxyhemoglobin becomes larger than the molar absorption coefficient of oxyhemoglobin. Further, in the case of generating a spectral image from photoacoustic images corresponding to two wavelengths, setting both wavelengths to wavelengths at which the molar absorption coefficient of deoxyhemoglobin becomes larger than the molar absorption coefficient of oxyhemoglobin is advantageous for imaging of veins. By selecting these wavelengths, both lymphatic vessels and veins injected with contrast agent can be imaged with high accuracy in the pre-operative examination of lymphatic venous anastomosis.

However, if all of the plurality of wavelengths are wavelengths at which the absorption coefficient of the contrast agent is larger than that of blood, the oxygen saturation accuracy of blood is lowered due to an artifact resulting from the contrast agent. Thus, to reduce artifacts originating from the contrast agent, at least one of the plurality of wavelengths may be a wavelength at which the absorption coefficient of the contrast agent is less than the absorption coefficient of blood.

Here, although the case where the spectral image is generated according to the formula (1) has been described, the present invention may also be applied to the case where the spectral image in which the image value corresponding to the contrast agent in the spectral image is changed in response to the condition of the contrast agent or the wavelength of the irradiation light is generated.

(S500: Process of irradiating light)

The light irradiation unit 110 sets the wavelength determined in S400 in the light source 111. The light source 111 emits light having the wavelength determined in S400. Light generated from the light source 111 is irradiated to the object 100 as pulsed light through the optical system 112. Then, the pulsed light is absorbed in the subject 100 to generate photoacoustic waves according to the photoacoustic effect. Here, the injected contrast agent also absorbs the pulsed light to generate photoacoustic waves. In addition to the transmission of pulsed light, the light irradiation unit 110 may transmit a synchronization signal to the signal collection unit 140. In addition, the light irradiation unit 110 performs irradiation of light in the same manner for a plurality of wavelengths.

The user can specify control parameters such as the irradiation conditions (the repetition frequency, the wavelength, and the like of the irradiation light) of the light irradiation unit 110 and the position of the probe 180 using the input unit 170. The computer 150 may set control parameters determined based on the user's instructions. Further, the computer 150 may control the driving unit 130 based on the designated control parameter so as to move the probe 180 to the designated position. In the case where imaging at a plurality of positions is specified, the driving unit 130 first moves the probe 180 to an initial specified position. In addition, the driving unit 130 may move the probe 180 to a pre-programmed position at the start of measurement indication.

(S600: Process of receiving photoacoustic wave)

When receiving the synchronization signal transmitted from the light irradiation unit 110, the signal collection unit 140 starts a signal collection operation. That is, the signal collection unit 140 generates an amplified digital electric signal by performing amplification and AD conversion on the analog electric signal derived from the photoacoustic wave output from the reception unit 120, and outputs the amplified digital electric signal to the computer 150. The computer 150 stores the signals transmitted from the signal collection unit 140. In the case where imaging at a plurality of scanning positions is specified, the processes of S500 and S600 are repeatedly performed at the specified scanning positions to repeatedly perform irradiation of pulsed light and generation of digital signals derived from acoustic waves. In addition, the computer 150 may acquire the position information of the receiving unit 120 at the time of emission of light based on the output from the position sensor of the driving unit 130 using the emission of light as a trigger, and store the position information.

In addition, although an example of irradiating light having a plurality of wavelengths in a time-division manner has been described in the present embodiment, the method of irradiating light is not limited thereto as long as signal data corresponding to a plurality of wavelengths can be acquired. For example, in the case of performing encoding using irradiation of light, there may be a timing of irradiating light having a plurality of wavelengths almost simultaneously.

(S700: Process of generating photoacoustic image)

The computer 150 as photoacoustic image acquiring means generates a photoacoustic image based on the stored signal data. The computer 150 outputs the generated photoacoustic image to the storage means 1200 so that the photoacoustic image is stored therein.

As a reconstruction algorithm for converting signal data into a two-dimensional or three-dimensional spatial distribution, an analytical reconstruction method such as a back projection method in the time domain and a back projection method in the fourier domain or a model-based method (iterative computation method) may be employed. For example, as a back projection method in the time domain, a universal back-projection (UBP), a filtered back-projection (FBP), a delay-and-sum (delay-and-sum), and the like can be assumed.

The computer 150 generates initial sound pressure distribution information (generated sound pressures at a plurality of positions) as photoacoustic images by performing reconstruction processing on the signal data. Further, the computer 150 may acquire the absorption coefficient distribution information as the photoacoustic image by calculating a light flux distribution (light flux distribution) in the subject 100 of the light irradiated to the subject 100 and dividing the initial sound pressure distribution by the light flux distribution. A known method can be used as the calculation method of the light flux distribution. Further, the computer 150 may generate photoacoustic images corresponding to the respective lights having the plurality of wavelengths. Specifically, the computer 150 may perform reconstruction processing on signal data obtained by irradiation of light having a first wavelength, thereby generating a first photoacoustic image corresponding to the first wavelength. Further, the computer 150 may perform reconstruction processing on signal data acquired by irradiation of light having the second wavelength, thereby generating a second photoacoustic image corresponding to the second wavelength. In this way, the computer 150 may generate a plurality of photoacoustic images corresponding to light having a plurality of wavelengths.

In the present embodiment, the computer 150 acquires absorption coefficient distribution information corresponding to light having a plurality of wavelengths as a photoacoustic image. It is assumed that the absorption coefficient distribution information corresponding to the first wavelength is a first photoacoustic image and the absorption coefficient distribution information corresponding to the second wavelength is a second photoacoustic image.

In addition, although an example in which the system includes the photoacoustic apparatus 1100 that generates a photoacoustic image has been described in the present embodiment, the present invention can also be applied to a system that does not include the photoacoustic apparatus 1100. The present invention can be applied to any system as long as the image processing apparatus 1300 as photoacoustic image acquiring means can acquire photoacoustic images. For example, the present invention can also be applied to a system including the storage apparatus 1200 and the image processing apparatus 1300 without including the photoacoustic apparatus 1100. In this case, the image processing apparatus 1300 as photoacoustic image acquiring means may acquire a photoacoustic image by reading a specified photoacoustic image from the group of photoacoustic images stored in advance in the storage apparatus 1200.

(S800: Process of generating spectral image)

The computer 150 as spectral image acquisition means generates a spectral image based on a plurality of photoacoustic images corresponding to a plurality of wavelengths. The computer 150 outputs the spectral image to the storage device 1200 and causes the storage device 1200 to store the spectral image. As described above, the computer 150 may generate, as a spectral image, an image representing information corresponding to the concentration of a substance constituting the subject (such as a glucose concentration, a collagen concentration, a melanin concentration, and a volume fraction of fat or water). Further, the computer 150 may generate, as the spectral image, an image representing a ratio of the first photoacoustic image corresponding to the first wavelength and the second photoacoustic image corresponding to the second wavelength. In the present embodiment, an example is described in which the computer 150 generates an oxygen saturation image according to formula (1) as a spectral image using the first photoacoustic image and the second photoacoustic image.

In addition, the image processing apparatus 1300 as spectral image acquisition means may acquire a spectral image by reading a specified spectral image from a group of spectral images stored in advance in the storage apparatus 1200. Further, the image processing apparatus 1300 as photoacoustic image acquiring means may acquire a photoacoustic image by reading at least one of a plurality of photoacoustic images for generating a read spectral image from a photoacoustic image group stored in advance in the storage apparatus 1200.

(S900: Process of acquiring information on a contrast agent based on a photoacoustic image or a spectral image)

The image processing apparatus 1300, which is a contrast agent information acquisition means, reads the photoacoustic image or the spectral image from the storage apparatus 1200, and acquires information about the contrast agent based on the photoacoustic image or the spectral image.

The information on the contrast agent acquired in S200 may not correspond to the condition of the contrast agent that has actually been injected into the subject 100 and has diffused into the subject 100. Accordingly, the image processing apparatus 1300 can perform image processing on the photoacoustic image or the spectral image and calculate information about the contrast agent from the photoacoustic image or the spectral image. Therefore, information on the contrast agent that has diffused into the subject 100 can be acquired from an image obtained by capturing the subject 100 in a state in which the contrast agent has been injected into the subject 100.

An example of estimating the contrast agent concentration from the image processing performed on the photoacoustic image in the case where the absorption coefficient distribution image is used as the photoacoustic image and the image having the value of formula (1) is used as the spectral image will be described. First, the user indicates the position of the contrast agent concentration in the photoacoustic image or the spectral image that the user wants to obtain. The image processing apparatus 1300 acquires image values of the photoacoustic image at the specified position. Further, the image processing apparatus 1300 acquires the absorption coefficient of the contrast agent of each concentration corresponding to the wavelength of the irradiation light with reference to the absorption coefficient spectrum shown in fig. 6. Here, the image processing apparatus 1300 may determine the type of the contrast agent of which absorption coefficient is to be acquired based on the information about the type of the contrast agent acquired in S200. Then, the image processing apparatus 1300 compares the absorption coefficient of the contrast agent of each concentration with the image value of the photoacoustic image, and acquires the contrast agent concentration having a smaller difference from the image value as information on the contrast agent. In addition, the image processing apparatus 1300 may calculate, as the information on the contrast agent, a density in a case where a norm (norm) representing a difference between an absorption coefficient of the contrast agent and an image value of the photoacoustic image is smaller than a predetermined value according to a least square method.

Further, an example of estimating the contrast agent concentration from image processing performed on the spectral image will be described. The image processing apparatus 1300 acquires image values of the spectral image at the specified position. Further, the image processing apparatus 1300 acquires the absorption coefficients of the contrast agents of the respective concentrations corresponding to the two wavelengths of the irradiation light with reference to the absorption coefficient spectrum shown in fig. 6. Further, image processing apparatus 1300 calculates a value corresponding to each density from equation (1) based on the absorption coefficient corresponding to each density. Then, the image processing apparatus 1300 compares the values of formula (1) corresponding to the respective densities with the image values of the spectral image, and acquires the contrast agent density having a smaller difference than the image values as information on the contrast agent. In addition, the image processing apparatus 1300 may calculate, as the information on the contrast agent, a density in a case where a norm representing a difference between the calculated value of formula (1) and the image value of the spectral image is smaller than a predetermined value according to a least square method.

Further, the computer 150 may read information about the contrast agent stored as supplementary information associated with the photoacoustic image or the spectral image to acquire the information about the contrast agent. For example, the computer 150 may read information about the contrast agent stored in a tag (tag) of a photoacoustic image or a spectral image, which is a DICOM image, to read the information about the contrast agent. According to this aspect, even when measurement of photoacoustic waves is not accompanied, the image processing apparatus 1300 can read images from the storage apparatus 1200 such as PACS and perform setting of image display and setting of wavelength depending on the condition of the contrast agent associated with the images.

In addition, the image processing apparatus 1300 may read the contrast agent type from the supplementary information associated with the image, and calculate the contrast agent density by image processing on the image. In this way, the image processing apparatus 1300 can acquire pieces of information about the contrast agent by a combination of different methods.

(S1000: Process of determining whether to reset wavelength)

The image processing apparatus 1300 determines whether to reset the wavelength. If the image processing apparatus 1300 determines to reset the wavelength, the process returns to S400, and if the image processing apparatus 1300 determines not to reset the wavelength, the process proceeds to S1100.

For example, in the case where an instruction for resetting of a wavelength is received from a user, the image processing apparatus 1300 determines to reset the wavelength. Here, the image processing apparatus 1300 may cause the display apparatus 1400 to display the information on the contrast agent acquired in S900. The user may then confirm the information displayed on the display device 1400 and indicate a reset of the wavelength using the input device 1500 when it is determined that the wavelength needs to be reset. In the case where an instruction for resetting of the wavelength is received through the input apparatus 1500, the image processing apparatus 1300 may determine to perform the resetting of the wavelength and cause the computer 150 to perform the resetting of the wavelength. In addition, the user may indicate the wavelength itself of the illumination light as an indication of the resetting of the wavelength.

Further, the image processing apparatus 1300 may compare the information on the contrast agent acquired in S200 with the information on the contrast agent acquired in S900, and determine the reset wavelength if there is a difference between these pieces of information.

Further, the image processing apparatus 1300 may compare the information on the contrast agent acquired in S200 with the information on the contrast agent acquired in S900, and if there is a difference between these pieces of information, cause the display apparatus 1400 to display the fact. Further, the image processing apparatus 1300 may cause information on the contrast agent having the difference to be displayed. The user can confirm the information displayed on the display device 1400 and instruct the resetting of the wavelength using the input device 1500 when it is determined that the wavelength needs to be reset. That is, the image processing apparatus 1300 may cause the display apparatus 1400 to display information based on the information on the contrast agent acquired in S900.

On the other hand, in the case where the image processing apparatus 1300 does not determine the reset wavelength, the process proceeds to S1100. For example, in a case where an instruction for resetting of a wavelength has not been received from the user within a certain time, the image processing apparatus 1300 may determine not to perform resetting of a wavelength. Further, in the case where an instruction indicating that the resetting of the wavelength is not to be performed is received from the user, the image processing apparatus 1300 may determine that the resetting of the wavelength is not to be performed. In addition, in the case where there is no difference between the information on the contrast agent acquired in S200 and the information on the contrast agent acquired in S900, the image processing apparatus 1300 may determine not to perform the resetting of the wavelength. In the case where at least one of these conditions has been received, the image processing apparatus 1300 may determine not to perform the resetting of the wavelength.

(S1100: Process of displaying spectral image)

The image processing apparatus 1300 as display control means causes the display apparatus 1400 to display a spectral image based on the information on the contrast agent acquired in S200 or S900 so that a region corresponding to the contrast agent and other regions can be distinguished. In addition, as the rendering (rendering) method, any method such as Maximum Intensity Projection (MIP), volume rendering, and surface rendering may be employed. Here, setting conditions such as a display area and a line-of-sight direction when a three-dimensional image is rendered two-dimensionally can be arbitrarily specified according to an observation target.

Here, a case will be described where the settings are 797nm and 835nm in S400 and a spectral image is generated according to formula (1) in S800. As shown in fig. 8, in the case where these two wavelengths are selected, the image value corresponding to the contrast agent in the spectral image generated according to the formula (1) is a negative value at any ICG concentration.

As shown in fig. 10, the image processing apparatus 1300 displays a color bar (colorbar)2400 as a color scale (color scale) representing a relationship between an image value of a spectral image and a display color on the GUI. The image processing apparatus 1300 may determine the numerical range of the image value assigned to the colorimetric scale based on information about the contrast agent (for example, information indicating that the contrast agent type is ICG) and information indicating the wavelength of the illumination light. For example, the image processing apparatus 1300 may determine a numerical range including the oxygen saturation level of an artery, the oxygen saturation level of a vein, and an image value that is a negative value corresponding to a contrast agent according to formula (1). The image processing apparatus 1300 may determine a numerical range of-100% to 100%, and set the color bar 2400 that assigns-100% to a gradation (colorgradation) that varies from blue to red. According to this display method, it is possible to identify arteriovenous and also identify a region having a negative value corresponding to a contrast agent. Further, the image processing apparatus 1300 may display an indicator 2410 based on the information about the contrast agent and the information indicating the wavelength of the irradiation light, the indicator 2410 indicating the numerical range of the image value corresponding to the contrast agent. Here, in the color bar 2400, a region having a negative value is represented as a numerical range of image values corresponding to ICG using an indicator 2410. By displaying the colorimetric scale in this manner so that the display color corresponding to the contrast agent can be recognized, the region corresponding to the contrast agent in the spectral image can be easily recognized.

The image processing apparatus 1300 as the region determining means may determine a region in the spectral image corresponding to the contrast agent based on the information on the contrast agent and the information indicating the wavelength of the irradiation light. For example, the image processing apparatus 1300 may determine a region having a negative image value in the spectral image as a region corresponding to the contrast agent. Then, the image processing apparatus 1300 may cause the display apparatus 1400 to display the spectral image so that the region corresponding to the contrast agent and the other region can be distinguished. The image processing apparatus 1300 may employ an identification representation such as making a display color of a region corresponding to the contrast agent different from that of other regions, blinking a region corresponding to the contrast agent, or displaying an indicator (e.g., a frame) representing a region corresponding to the contrast agent.

In addition, an item 2730 corresponding to the display of the ICG displayed on the GUI shown in fig. 10 may be instructed to switch to a display mode in which image values corresponding to the ICG are selectively displayed. For example, in a case where the user selects an item 2730 corresponding to the display of the ICG, the image processing apparatus 1300 may selectively display a region of the ICG by selecting a voxel (voxel) having a negative image value from the spectral image and selectively rendering the selected voxel. Likewise, the user may select an item 2710 corresponding to display of an artery or an item 2720 corresponding to display of a vein. The image processing apparatus 1300 may switch to a display mode in which image values corresponding to an artery (for example, at least 90% and not more than 100%) or image values corresponding to a vein (for example, at least 60% and not more than 90%) are selectively displayed, based on an instruction of a user. The numerical range of the image value corresponding to the artery and the image value corresponding to the vein may be changed based on the user's instruction.

In addition, an image obtained by assigning at least one of hue, brightness, and chroma to the image values of the spectral image and assigning the remaining parameters of hue, brightness, and chroma to the image values of the photoacoustic image may be displayed as the spectral image. For example, an image obtained by assigning hue and chroma to image values of a spectral image and assigning brightness to image values of a photoacoustic image may be displayed as a spectral image. Here, when the image value of the photoacoustic image corresponding to the contrast agent is larger or smaller than the image value of the photoacoustic image corresponding to the blood vessel, there is a case where it is difficult to visually recognize both the blood vessel and the contrast agent when the brightness is assigned to the image value of the photoacoustic image. Therefore, the conversion table for converting the image value of the photoacoustic image to the luminance can be changed in response to the image value of the spectral image. For example, in the case where the image value of the spectral image is included in the numerical range of the image value corresponding to the contrast agent, the luminance corresponding to the image value of the photoacoustic image may be reduced to be smaller than the luminance corresponding to the blood vessel. That is, if the image values of the photoacoustic image are the same when comparing the region of the contrast agent with the region of the blood vessel, the brightness of the region of the contrast agent can be reduced to be smaller than the brightness of the region of the blood vessel. Here, the conversion table is a table indicating luminances corresponding to a plurality of image values. Further, in the case where the image value of the spectral image is included in the numerical range of the image value corresponding to the contrast agent, the luminance corresponding to the image value of the photoacoustic image may be increased to be larger than the luminance corresponding to the blood vessel. That is, if the image values of the photoacoustic image are the same when comparing the region of the contrast agent with the region of the blood vessel, the luminance of the region of the contrast agent can be increased to be greater than the luminance of the region of the blood vessel. Further, the numerical range of the image value of the photoacoustic image, which does not convert the image value of the photoacoustic image into luminance, may vary depending on the image value of the spectral image.

The conversion table may be changed to an appropriate table according to the type and concentration of the contrast agent or the wavelength of the irradiation light. Accordingly, the image processing apparatus 1300 can determine the conversion table for converting the image value of the photoacoustic image into the luminance based on the information on the contrast agent and the information indicating the wavelength of the irradiation light. In a case where it is estimated that the image value of the photoacoustic image corresponding to the contrast agent is larger than the image value of the photoacoustic image corresponding to the blood vessel, the image processing apparatus 1300 may decrease the luminance of the image value corresponding to the photoacoustic image corresponding to the contrast agent to be smaller than the luminance of the image value corresponding to the photoacoustic image corresponding to the blood vessel. On the other hand, in a case where it is estimated that the image value of the photoacoustic image corresponding to the contrast agent is smaller than the image value of the photoacoustic image corresponding to the blood vessel, the image processing apparatus 1300 may increase the luminance of the image value corresponding to the photoacoustic image corresponding to the contrast agent to be larger than the luminance of the image value corresponding to the photoacoustic image corresponding to the blood vessel.

The GUI shown in fig. 10 displays an absorption coefficient image (first photoacoustic image) 2100 corresponding to the wavelength 797nm, an absorption coefficient image (second photoacoustic image) 2200 corresponding to the wavelength 835nm, and an oxygen saturation image (spectral image) 2300. The GUI may display images that each image is generated from light having which wavelength. Although both the photoacoustic image and the spectral image are displayed in the present embodiment, only the spectral image may be displayed. Further, the image processing apparatus 1300 may switch between display of the photoacoustic image and display of the spectral image based on an instruction of the user.

In addition, the display unit 160 may display a moving image. For example, a configuration may be adopted in which the image processing apparatus 1300 generates at least any one of the first photoacoustic image 2100, the second photoacoustic image 2200, and the spectral image 2300 in time series, generates moving image data based on the generated time-series images, and outputs the moving image data to the display unit 160. In addition, in view of the relatively small number of times of lymphatic flow, it is preferable to display a still image or a moving image compressed with time to reduce the judgment time of the user. Further, in the display of the moving image, the lymphatic flow state may be repeatedly displayed. The moving image speed may be a predetermined speed defined in advance or a predetermined speed designated by a user.

Further, in the display unit 160 capable of displaying a moving image, it is preferable that the frame rate of the moving image is variable. To set a variable frame rate, a window for a user to manually input the frame rate, a slider bar for changing the frame rate, or the like may be added to the GUI of fig. 10. Here, since the lymph is intermittently flowing in the lymphatic vessels, only a part of the acquired time-series volume data can be used to confirm the flow of the lymph. Therefore, there is a case where the efficiency is reduced when the real-time display is performed while confirming the flow of the lymph fluid. Accordingly, by setting a variable frame rate of the moving image displayed on the display unit 160, the moving image can be displayed in a fast-forward manner, and the user can confirm the state of the fluid in the lymphatic vessel in a short time.

Further, the display unit 160 may repeatedly display moving images within a predetermined time range. Here, it is also preferable to add a GUI such as a window or a slider for enabling the user to specify a range in which the repeated display is performed to fig. 10. Therefore, the user can easily find out the state of the fluid flowing in the lymphatic vessel, for example.

As described above, at least one of the image processing apparatus 1300 and the computer 150 as the information processing apparatus functions as an apparatus including at least one of the spectral image acquisition means, the contrast agent information acquisition means, the region determination means, the photoacoustic image acquisition means, and the display control means. In addition, the respective components may be configured as different hardware or a single hardware. Further, a plurality of components may be configured as a single hardware.

Although the contrast agent and the blood vessel can be distinguished by selecting a wavelength at which the value according to formula (1) corresponding to the contrast agent becomes a negative value in the present embodiment, the image value corresponding to the contrast agent may be any value as long as the contrast agent and the blood vessel can be distinguished using the image value corresponding to the contrast agent. For example, in the case where the image value of the spectral image (oxygen saturation image) corresponding to the contrast agent is less than 60% or more than 100%, or the like, the image processing described in the present procedure can also be applied.

Although an example of a case where ICG is used as a contrast agent has been described in the present embodiment, the image processing according to the present embodiment can be applied to any contrast agent other than ICG. Further, the image processing apparatus 1300 may perform image processing depending on the type of contrast agent based on information of the type of contrast agent injected into the subject 100 among a plurality of types of contrast agents.

The case where the image processing method is determined based on the acquired information on the contrast agent among the plurality of pieces of information on the contrast agent has been described in the present embodiment. However, in the case where the condition of the contrast agent for imaging has been uniquely determined, image processing corresponding to the condition of the contrast agent may be set in advance. In this case, the image processing according to the present embodiment described above can also be applied.

Although an example in which image processing is applied to spectral images based on photoacoustic images corresponding to a plurality of wavelengths has been described in the present embodiment, image processing according to the present embodiment may also be applied to photoacoustic images corresponding to a single wavelength. That is, the image processing apparatus 1300 may determine a region corresponding to the contrast agent in the photoacoustic image based on the information about the contrast agent and display the photoacoustic image so that the region corresponding to the contrast agent and other regions can be distinguished. Further, the image processing apparatus 1300 may display a spectral image or a photoacoustic image so that a region having a numerical value range of image values corresponding to a contrast agent set in advance can be distinguished from other regions.

Although an example in which the computer 150 as the information processing apparatus irradiates light with a plurality of wavelengths to generate a spectral image is described in the present embodiment, in the case of irradiating only light with a single wavelength to generate a photoacoustic image, the wavelength may also be determined by the wavelength determination method according to the present invention. That is, the computer 150 may determine the wavelength of the illumination light based on information about the contrast agent. In this case, it is preferable that the computer 150 determines a wavelength that enables the image value of the contrast agent region in the photoacoustic image to be distinguished from the image value of the blood vessel region.

In addition, the light irradiation unit 110 may irradiate the subject 100 with light having a wavelength set in advance so that an image value of a contrast agent region in the photoacoustic image can be distinguished from an image value of a blood vessel region. Further, the light irradiation unit 110 may irradiate the subject 100 with light having a plurality of wavelengths set in advance so that the image value of the contrast agent region in the spectral image can be distinguished from the image value of the blood vessel region.

(other embodiments)

Further, the present invention is also realized by executing the following processing. That is, software (program) for realizing the functions of the above-described embodiments is supplied to a system or an apparatus via a network or various storage media, and a computer (or CPU, MPU, or the like) of the system or the apparatus reads and executes the program.

The present invention is not limited to the above-described embodiments, and may be modified and changed in various ways without departing from the spirit and scope of the invention. Therefore, the following claims should be studied to determine the true scope of the invention.

The present invention claims priority from japanese patent application No. 2018-155033 filed on 21/8/2018, the contents of which are incorporated herein by reference.

List of reference numerals

1100 photoacoustic apparatus

1200 memory device

1300 image processing device

1400 display device

1500 input device