JP5424846B2 - Photoacoustic imaging device - Google Patents

Description

  The present invention relates to a technique that can be suitably applied to photoacoustic imaging.

Active research in non-invasive optical imaging devices that obtain in-vivo information by propagating visible to infrared light emitted from a light source into the living body and detecting light and acoustic waves in the medical field It has been.
As one of the optical imagings, there is a photoacoustic imaging technique called PAT (Photo Acoustic Tomography). In photoacoustic imaging, a living body is irradiated with pulsed light generated from a light source, and an acoustic wave generated from a living tissue that has absorbed energy of pulsed light that has propagated and diffused in the living body is detected by an acoustic wave detector. This is a technique for imaging a light characteristic distribution in a living body, in particular, a light energy absorption density distribution from the detection signal.

As an example of the photoacoustic imaging apparatus, Non-Patent Document 1 discloses an example of the apparatus. In Non-Patent Document 1, the detector is arranged only in a part of the periphery of the subject. Considering that the spherical wave generated from the subject is emitted in all directions and the problem of the size and wiring of the detector, it is common practice to place the detector only in a limited range. As described above, in Non-Patent Document 1, the acoustic detector is arranged so as to acquire only the acoustic wave generated in one direction among the acoustic waves generated from the light absorber.
In Patent Document 1, an object is placed at one focus of an elliptical spherical acoustic reflection member, and a detector is placed at the other focus to detect all acoustic waves emitted from the object and increase the signal intensity. ing.

JP 2006-208050 A

Srirang Manohar, et. Al., “Region-of-interest breast images with the Twente Photoacoustic Mammoscope (PAM)”, Proc. Of SPIE, Vol. 6437, 643702, 2007.

  However, when the acoustic wave detector is arranged so as to detect an acoustic wave only in a specific direction as in Non-Patent Document 1, the acoustic wave emitted from the light absorber in the other direction cannot be received. The reproducibility cannot be maintained. Shape reproducibility refers to the possibility that the shape of a light absorber that is a sound source can be reproduced with a reconstructed image. For example, as shown in FIG. 9A, since a spherical wave is emitted from a point-like or spherical light absorber and a photoacoustic wave heading toward the detector always exists, at the time of reconstruction, as shown in FIG. Shape reproducibility can be maintained. However, as shown in FIG. 9C, in the slab or linear light absorber, a spherical wave is emitted from the end also in the detection direction, but a plane wave is emitted only in the vertical direction from the intermediate portion. . For this reason, there is a portion that does not emit photoacoustic waves toward the detector (all intermediate portions here), and only an image as shown in FIG. 9D is obtained, and shape reproducibility cannot be maintained. .

Patent Document 1 also only receives an acoustic wave from a light absorber that emits an acoustic wave toward the detector from another direction using an acoustic reflecting member. That is, even in Patent Document 1, information on a light absorber that emits an acoustic wave in a direction not facing the detector cannot be obtained, and shape reproducibility cannot be maintained.

  In consideration of the above problems, the present invention is based on the shape of the sound source even if there is no acoustic wave toward the detector due to the shape of the sound source or the positional relationship between the sound source and the detector. The purpose is to improve reproducibility.

A first aspect of the present invention is a light source that irradiates a subject with light, an acoustic wave detector that detects a photoacoustic wave emitted from the subject and converts it into an electrical signal, and is emitted from the subject. An acoustic reflection unit that reflects a photoacoustic wave to the acoustic wave detection unit, and an arithmetic processing unit that obtains an information image in the subject based on the photoacoustic wave detected by the acoustic wave detection unit, The arithmetic processing unit obtains spatial information by performing reconstruction processing based on the electrical signal converted by the acoustic wave detection unit, and a relative position between the acoustic wave detection unit and the acoustic reflection unit, and Using an angle, the image included in the spatial information is a real image based on the direct acoustic wave that is directly incident on the acoustic wave detection unit, and the reflected sound that is reflected on the acoustic reflection unit and incident on the acoustic wave detection unit. The acoustic wave detector is distinguished from a virtual image based on a wave. A real image based on the reflected acoustic wave is obtained from a virtual image based on the reflected acoustic wave using a relative position and angle of the acoustic reflecting unit, and the direct acoustic wave is obtained using the real image based on the reflected acoustic wave. The photoacoustic imaging apparatus is characterized in that an information image in the subject is acquired by complementing a real image obtained by the above.

According to a second aspect of the present invention, there is provided a method for analyzing subject information in a photoacoustic imaging apparatus including an acoustic wave detection unit and an acoustic reflection unit, the photoacoustic being emitted from the subject by light irradiated on the subject. A detection step of detecting a wave by the acoustic wave detection unit to acquire an electrical signal, and a calculation processing step of obtaining an information image in the subject based on the photoacoustic wave detected by the acoustic wave detection unit. Including the step of performing spatial reconstruction processing based on the electrical signal acquired in the detection step and acquiring spatial information, and the relative position of the acoustic wave detection unit and the acoustic reflection unit. Using the angle and the angle, the image included in the information image is a real image based on the direct acoustic wave directly incident on the acoustic wave detection unit, and the reflection reflected on the acoustic reflection unit and incident on the acoustic wave detection unit Acoustic wave And a step of acquiring a real image based on the reflected acoustic wave from a virtual image based on the reflected acoustic wave using a relative position and angle of the acoustic wave detecting unit and the acoustic reflecting unit. And a step of complementing the real image based on the direct acoustic wave by using the real image based on the reflected acoustic wave.

According to a third aspect of the present invention, there is provided a computer program for obtaining subject information in a photoacoustic imaging apparatus including an acoustic wave detection unit and an acoustic reflection unit, wherein the subject is irradiated with light irradiated on the subject. An acquisition step of acquiring a detection signal of a photoacoustic wave radiated from a specimen, and an arithmetic processing step of acquiring an information image in the subject based on the acquired detection signal are executed. Based on the detection signal, the processing step performs a reconstruction process to acquire an information image, and uses the relative positions and angles of the acoustic wave detection unit and the acoustic reflection unit to generate the information image. A real image based on a direct acoustic wave directly incident on the acoustic wave detection unit, and a virtual image based on a reflected acoustic wave reflected on the acoustic reflection unit and incident on the acoustic wave detection unit. Distinguishing, using the relative position and angle of the acoustic wave detection unit and the acoustic reflection unit, calculating a real image based on the reflected acoustic wave from a virtual image based on the reflected acoustic wave, and the reflection And a step of complementing the real image based on the direct acoustic wave using a real image based on the acoustic wave.

  According to the present invention, the multi-directional acoustic wave generated from the absorber can be detected by the photoacoustic wave detector, so that the reproducibility of the shape can be greatly improved.

Configuration example of biological information imaging apparatus according to first embodiment Functional block diagram of biological information imaging apparatus Flow chart of processing performed by biological information imaging apparatus Explanatory drawing of the image formation process and final image in 1st Embodiment Configuration example of biological information imaging apparatus according to second embodiment Explanatory drawing of the image formation process in 2nd Embodiment Configuration example of biological information imaging apparatus according to third embodiment Explanatory drawing of the image formation process in 3rd Embodiment Example of reconstructed image according to the prior art

<First Embodiment>
[Overview]
A biological information imaging apparatus (photoacoustic imaging apparatus) according to a first embodiment of the present invention will be described with reference to FIG. FIG. 1 is a diagram illustrating a configuration example of a biological information imaging apparatus according to the present embodiment. The biological information imaging apparatus of the present embodiment enables imaging of optical characteristic distribution in a living body (subject) for diagnosis of tumors such as breast cancer and vascular diseases, and for follow-up of chemical treatment. . An image obtained by imaging subject information is referred to as an information image.

In the biological information imaging apparatus of this embodiment, the living body 12 is irradiated with the light 20 from the pulse light source 11. The irradiated light 20 diffuses in the living body and is absorbed by the tumor, blood vessel, contrast agent introduced into the living body, or a similar light absorbing body 13 in the living body (in the subject). An acoustic wave (elastic wave) 18 generated by thermal expansion of the light absorber 13 is detected by an acoustic wave detector (acoustic wave detection unit) 14. The arithmetic processing unit 16 images biological information by reconstructing the detected acoustic wave.

  Further, in order to make the acoustic wave 18 that has not directly entered the acoustic wave detector 14 incident on the acoustic wave detector 14, the acoustic reflection unit 15 in which the space between the living body and the acoustic reflection unit 15 is filled with the acoustic matching material 21 is acoustically generated. It is provided in a different direction from the wave detector 14. As a result, the detector 14 can receive the acoustic wave that directly enters the acoustic wave detector 14 and the acoustic wave 18 that does not directly enter the acoustic wave detector.

The biological information imaging apparatus according to the present embodiment includes the following units.
[Pulse light source]
The pulsed light source 11 is used as means for irradiating pulsed light having a specific wavelength that is absorbed by a specific component among the components constituting the living body. In the present embodiment, near-infrared light having a pulse width of 10 nanoseconds or less is used as pulsed light, but pulsed light having a pulse width on the order of several nanoseconds to several hundred nanoseconds may be employed.
A laser is preferable as the light source, but a light emitting diode or the like may be used instead of the laser. As the laser, various lasers such as a solid laser, a gas laser, a dye laser, and a semiconductor laser can be used.
The pulse light source 11 may be composed of one light source, but may be composed of a plurality of light sources. When the pulsed light source 11 is configured by using a plurality of light sources, a plurality of light sources that oscillate the same wavelength may be used in order to increase the irradiation intensity of the light applied to the living body. In order to measure the difference in the optical characteristic value distribution depending on the wavelength, a plurality of light sources having different oscillation wavelengths may be used. In addition, if a oscillating wavelength-convertable dye or OPO (Optical Parametric Oscillators) can be used, it is possible to measure the difference in the optical characteristic value distribution depending on the wavelength. Regarding the wavelength of the light source to be used, a region of 700 nm to 1100 nm, which is less absorbed in the living body, is preferable. When obtaining the optical characteristic value distribution of the living tissue relatively near the surface of the living body, it is also possible to use a wavelength region having a wider range than the above wavelength region, for example, a wavelength region of 400 nm to 1600 nm.

[Acoustic wave detector]
An acoustic wave detector (hereinafter also simply referred to as “detector”) 14 detects an acoustic wave generated from a light absorber in the living body that has absorbed the energy of light irradiated on the living body, and converts it into an electrical signal. That is, the detector 14 receives an acoustic wave and outputs an electrical signal according to the pressure of the received acoustic wave. As the detector 14, a transducer using a piezoelectric phenomenon, a transducer using optical resonance, a transducer using a change in capacitance, or the like can be used, and the type thereof is not particularly limited.
Further, in the present embodiment, the case where the array-like detector is arranged on the surface of the living body is shown. However, the present invention is not limited to such an arrangement, and tomography is performed so that acoustic waves can be detected at a plurality of locations. It only has to be done.
That is, since the same effect can be obtained if acoustic waves can be detected at a plurality of locations, one acoustic wave detector may be scanned two-dimensionally on the surface of the living body. Further, the positional relationship between the light source and the acoustic wave detector is not limited to the mode shown in the figure, and for example, the acoustic wave detector may be arranged in the same direction with respect to the living body.

[Sound reflection part]
The acoustic reflector (hereinafter also simply referred to as “reflector”) 15 reflects the photoacoustic wave emitted from the light absorber 13 in the living body 12 toward the detector 14. The reflection unit 15 can be configured by one or a plurality of reflection units. In order to avoid loss of the photoacoustic signal at the boundary surface of the living body 12, the reflection unit 15 is disposed in the acoustic matching material 21 having substantially the same acoustic impedance as that of the living body 12. The reflecting portion 15 is preferably made of a material such as stainless steel or aluminum that has a high reflectivity with respect to the photoacoustic signal and is stable with respect to the acoustic matching material 21.
Moreover, in this embodiment, although the reflection part 15 which has a plane acoustic reflection surface is arrange | positioned with respect to the detector 14 in the orthogonal | vertical direction, arrangement | positioning of the reflection part 15 is not restricted to this. The reflection unit 15 may be arranged in any way as long as the position and angle allow the acoustic wave radiated from within the target region and not directed to the detector 14 to be reflected by the detector 14. Note that the inside of the target region is a region to be imaged and refers to a range in which the pulsed light irradiated with the light source can propagate.
The reflection unit 15 may include a reflection unit control axis (control unit) 23 that changes an angle and a position in order to reflect an acoustic wave from various regions to the acoustic wave detector.

[Operation processing unit]
The arithmetic processing unit 16 reconstructs the detection signal of the acoustic wave detected by the detector 14 to calculate the spatial information of the voxelized living body. The arithmetic processing unit 16 performs a reconstruction process using a reverse projection method or the like on the detected intensity of the acoustic wave and information on its temporal change, and converts the information into an optical characteristic value distribution (light energy absorption density distribution). The arithmetic processing unit 16 uses the positional information and angle information of the reflecting unit 15 to directly enter the detector 14 and an image of an acoustic wave (reflected acoustic wave) reflected by the reflecting unit 15 and incident on the detector 14. Distinguish images from acoustic waves (direct acoustic waves). The actual sound source position of the reflected acoustic wave can be obtained from the angle of the reflection unit 15 and the positional relationship between the reflection unit 15 and the detector 14. That is, the arithmetic processing unit 16 can calculate the spatial information of the living body from the reflected acoustic wave. And the arithmetic processing part 16 produces image information by complementing the spatial information obtained from a direct acoustic wave with the spatial information obtained from a reflected acoustic wave. Image information obtained by the processing of the arithmetic processing unit 16 is displayed on the image display unit 17.
The arithmetic processing unit 16 can be configured by a computer including a CPU (Central Processing Unit), a main storage device (memory), an auxiliary storage device (such as a hard disk), and an input device, for example. A computer program for realizing the functions of the arithmetic processing unit 16 is stored in the auxiliary storage device of the computer. When the CPU loads a program from the auxiliary storage device to the main storage device and executes it, the CPU functions as each functional unit shown in FIG. Moreover, the arithmetic processing part 16 performs the process step of S3-S5 shown by FIG. 3, and produces | generates biological image data (information image) from measurement data.

Hereinafter, details of the analysis method of the subject information performed by the arithmetic processing unit 16 will be described with reference to the drawings. First, the living body 12 is irradiated with light from the pulse light source 11 (S1), and the photoacoustic wave emitted from the light absorber 13 is detected by the detector 14 (S2). Then, the spatial information calculation unit 103 calculates the voxelized spatial information (voxel data) using the detected acoustic wave information (S3). Note that at this stage, without distinguishing whether the detected acoustic wave is a direct acoustic wave or a reflected acoustic wave, a reconstruction process is performed using all the detected acoustic waves to obtain spatial information. Calculate. Therefore, the spatial information calculated by the spatial information calculation unit 103 includes an image 50 obtained from the reflected acoustic wave reflected by the reflecting unit 15 as shown in FIG.
Next, the spatial information identification unit 104 distinguishes the generated spatial information into an image obtained from a direct acoustic wave and an image obtained from a reflected acoustic wave (S4). The position of the image obtained from the direct acoustic wave and the reflected acoustic wave is determined from the position and angle of the reflecting portion 15 obtained from the reflecting portion position / angle detecting means 101 and the position of the detector 14 obtained from the detector position detecting means 102. Can be sought. Specifically, a region 51 that is a shadow of the reflection unit 15 when viewed from the detector 14 is calculated, and an image included in the region 51 can be determined to be an image by a reflected acoustic wave. In addition, it can be determined that the image included in the other region 52 is an image by a direct acoustic wave. Here, the region where the image by the reflected acoustic wave is located is called an imaginary space, and the region where the image by the direct acoustic wave is located is called a real space.
The spatial information identification unit 104 can calculate the range (region 51) of the imaginary space from the positional relationship between the detector 14 and the reflection unit 15. A range other than the imaginary space (region 52) is regarded as a real space range. The range of the real space obtained in this way includes a region where the living body 12 cannot exist. However, even if regarded as described above, no problem occurs, and arithmetic processing can be realized by simple processing. In this way, the spatial information identification means 104 separates the image (spatial information) from the direct acoustic wave and the image (spatial information) from the reflected acoustic wave.
The positions of the reflection unit 15 and the detector 14 can be acquired by the reflection unit position / angle detection unit 101 and the detector position detection unit 102 which are sensors composed of a linear encoder or a rotary encoder. Moreover, it is good also as a structure which detects the relative position and angle with respect to the detector 14 of the reflection part 15 without detecting each position of the detector 14 and a reflection part.
The spatial information complementing means 105 obtains a corresponding real space image (real image) from a virtual image (virtual space information) obtained from the reflected wave at the reflecting section 15 and directly obtains an image (real space information) obtained from the acoustic wave. In addition, a complemented information image is obtained (S5). The position in the real space corresponding to the position in the imaginary space can be realized by coordinate transformation that matches the coordinates in the imaginary space with the coordinates in the real space. When a planar reflection unit is used as in this embodiment, information between the imaginary space and the real space can be converted using plane symmetry with respect to the reflection unit. Spatial information obtained by supplementing real space information using imaginary space information is shown in FIG. Thus, the space information generated using the real space information and the imaginary space information is displayed on the image display unit 17 (S6). In FIG. 4A, the virtual image space is displayed for explanation, but this virtual space may not necessarily be displayed as an actual imaging apparatus.

Furthermore, when looking in detail at a part suspected to be a tumor or a vascular disease in the living body, the angle or position of the reflection part is changed using the reflection part control axis 23 while fixing the acoustic wave detector and the light irradiation position. And measure at each angle or position. At this time, it is preferable that the real space information is complemented with the imaginary space information at the angles or positions of the respective reflecting portions, and the complemented distribution maps are added together. By changing the position and angle of the reflecting portion, it is possible not only to image light absorbers in various regions, but also to image light absorbers that emit photoacoustic waves only in specific directions with good reproducibility.
When there are a plurality of reflectors, real space information may be supplemented using imaginary space information by sound waves that have entered the detector after multiple reflections. It is possible to determine whether multiple reflection has occurred or to specify the position of the sound wave source (coordinate conversion processing) when multiple reflection has occurred in the same manner as described above.

  As described above, the acoustic wave from the light absorber that does not emit the acoustic wave in the direction toward the detection unit is reflected by the acoustic reflection unit and detected by the detector, so that the slab-like or linear light absorption is performed. Body shape reproducibility can be improved.

<Second Embodiment>
Next, a biological information imaging apparatus according to the second embodiment of the present invention will be described. FIG. 5 illustrates a configuration example of the biological information imaging apparatus according to the present embodiment. In addition, the same code | symbol is attached | subjected about the same structure as FIG.

  In the present embodiment, the light irradiated from the light source 11 is irradiated to the living body 12 from the side (in a direction orthogonal to the normal of the detector surface) via the optical waveguide 22. And the reflection part 24 with the curved acoustic reflection surface is provided in the opposite side to the light irradiation side. The reflection unit 24 is for causing the acoustic wave 18 that does not enter the detector 14 to enter the detector 14. It is also preferable to further include a reflection unit control axis (control unit) 23 for moving or rotating the reflection unit 24. By changing the position and angle of the reflection unit 24, acoustic waves from various regions can be reflected to the detector 14.

As in the first embodiment, the arithmetic processing unit 16 calculates spatial information from the acoustic wave detected by the detector 14, and distinguishes it into an image by a direct acoustic wave and an image (virtual image) by a reflected acoustic wave, Coordinate the virtual image and superimpose it on real space information. As shown in FIG. 6, the imaginary space 51 can be obtained from the positional relationship between the detector 14 and the reflector 24. Since the shape of the reflector 24 and the positional relationship with the detector 14 are known, the virtual image 50 can be converted into a real image. Such conversion can be expressed as a coordinate conversion matrix. Then, the spatial information of the light absorber 13 is obtained by superimposing the spatial information obtained by coordinate conversion of the virtual image with the spatial information of the real image.

  Thus, also in this embodiment, the shape reproducibility of the slab-like or linear light absorber can be improved as in the first embodiment.

In the present embodiment, the acoustic reflector 24 is arranged in a direction perpendicular to the acoustic wave detector 14, but the angle at which the acoustic wave from the target region is reflected by the acoustic wave detector outside the range of the detector. If so, it can be anywhere.
In addition, it is also preferable to perform measurement a plurality of times while changing the position and angle of the reflection unit 24 and add the information images obtained by each measurement and display them as one information image. Although it is considered that there is a subject region where the photoacoustic wave cannot be detected depending on the position and angle of the reflecting portion, by performing multiple measurements by changing the position and angle of the reflecting portion 24, detection omission can be reduced, Therefore, shape reproducibility is improved.
It is also preferable to scan or move the position of the light source in order to change the biological imaging region. Further, the position of the optical waveguide instead of the light source may be changed. Furthermore, instead of moving the light source or the like, the same light source may be arranged at a plurality of positions.

<Third Embodiment>
Next, a biological information imaging apparatus according to Embodiment 3 of the present invention will be described. FIG. 7 illustrates a configuration example of the biological information imaging apparatus according to the present embodiment. In addition, the same code | symbol is attached | subjected about the same structure as FIG.

  The living body imaging apparatus according to the present embodiment includes a pulse light source 11 and an optical waveguide 22 that guides light emitted from the light source 11 to the living body 12. In this embodiment, the living body 12 is irradiated with light from the pulse light source 11 from the same direction as the detector 14. The living body 12 is immersed in a container 25 filled with an acoustic matching material, for example, an acoustic matching gel or water.

  In addition, the living body imaging apparatus according to the present embodiment includes an acoustic reflection unit 15 in order to cause the acoustic wave 18 that has not entered the acoustic wave detector 14 to enter the acoustic wave detector 14. The container 25 has a trapezoidal shape, the detector 14 is provided on the long side, and the reflecting portion 15 is provided on each of the oblique sides. Thereby, the acoustic wave 18 that has not been directed to the detector 14 can be reflected and incident on the detector 14.

  As in the first and second embodiments, the arithmetic processing unit 16 calculates spatial information from the acoustic wave detected by the detector 14 and directly distinguishes between an image by the acoustic wave and an image by the reflected acoustic wave (virtual image). The virtual image is coordinate-transformed and superimposed with real-space information. As shown in FIG. 8, the imaginary space 51 can be obtained from the positional relationship between the detector 14 and the reflection unit 15. Since the shape of the reflector 15 and the positional relationship with the detector 14 are known, the virtual image 50 can be converted into a real image. Such conversion can be expressed as a coordinate conversion matrix. Then, the spatial information of the light absorber 13 is obtained by superimposing the spatial information obtained by coordinate conversion of the virtual image with the spatial information of the real image.

  In order to reduce artifacts due to multiple reflections, an acoustic absorption unit 26 may be provided on the wall of the container 25, not the detector 14 or the reflection unit 15. Further, although the trapezoidal container has been described as an example, the shape of the container 25 is not necessarily limited to the trapezoidal shape, and may be an arbitrary shape.

11..Pulse light source, 12 .... Biological body, 13..Light absorber, 14..Detector, 15..Reflection unit, 16 .... Calculation processing unit, 24..Reflection unit

Claims (11)

A light source for irradiating the subject with light;
An acoustic wave detector that detects a photoacoustic wave emitted from the subject and converts it into an electrical signal ;
An acoustic reflector that reflects the photoacoustic wave emitted from the subject to the acoustic wave detector;
Based on the photoacoustic wave detected by the acoustic wave detecting unit, and the arithmetic processing unit for obtaining the information image in the subject,
Have
The arithmetic processing unit includes:
Based on the electrical signal converted by the acoustic wave detection unit , reconstruct processing is performed to obtain spatial information,
Using the relative position and angle of the acoustic reflector portion and the acoustic wave detector, an image contained prior Kisora between information, and the real image based on the direct acoustic wave directly incident to the acoustic wave detector , said reflected acoustic reflector portion is divided into the imaginary image based on the reflected acoustic waves incident to the acoustic wave detector,
From the imaginary image based on the reflected acoustic wave by using the relative position and angle of the acoustic reflector portion and the acoustic wave detection unit, obtains the real image based on the reflected acoustic waves,
Using the real image based on the previous SL reflected acoustic waves, the direct acoustic wave photoacoustic imaging apparatus according to claim <br/> to obtain information image in the subject by complementing the actual image by. The arithmetic processing unit, and a shape and a relative position and angle of the said acoustic wave detector acoustic reflector portion, obtains the region of the space where imaginary image based on the reflected acoustic waves is obtained, contained in the area photoacoustic imaging apparatus according to claim 1, characterized in that it is determined that the imaginary image by the reflected acoustic wave image to be.   The photoacoustic imaging apparatus according to claim 1, wherein the acoustic reflection unit has a flat acoustic reflection surface.   The photoacoustic imaging apparatus according to claim 1, wherein the acoustic reflection unit has a curved acoustic reflection surface. The said acoustic reflection part is one or more, The any one of Claims 1-4 characterized by the above-mentioned.
Item 2. The photoacoustic imaging apparatus according to item 1.   The photoacoustic imaging apparatus according to claim 1, further comprising a control unit configured to move or rotate the acoustic reflection unit. Measurement is performed a plurality of times by changing the position or angle of the acoustic reflection unit, and the calculation processing unit acquires an information image in the subject for each measurement, and adds the obtained information images together. The photoacoustic imaging apparatus according to claim 6. A method for analyzing object information in a photoacoustic imaging apparatus including an acoustic wave detection unit and an acoustic reflection unit,
A detection step of obtaining an electric signal by detecting a photoacoustic wave, wherein the test body or al emitted by the light irradiated to the subject by the acoustic wave detecting unit,
Based on the photoacoustic wave detected by the acoustic wave detecting unit, and the arithmetic processing step of obtaining the information image in the subject,
Including
The arithmetic processing step includes
Based on the electrical signal acquired in the detection step, performing a reconstruction process to acquire spatial information;
Using the relative position and angle of the acoustic reflector portion and the acoustic wave detector, an image contained prior Kijo paper image, the real image based on the direct acoustic wave directly incident to the acoustic wave detector a distinguishing step and imaginary image based on the reflected acoustic waves incident to the acoustic wave detector is reflected to the acoustic reflector portion,
From the imaginary image based on the reflected acoustic wave by using the relative position and angle of the acoustic reflector portion and the acoustic wave detector, acquiring a real image based on the reflected acoustic waves,
Using the real image based on the previous SL reflected acoustic waves, comprising the steps of: complementing the real image based on the direct acoustic waves,
A method for analyzing subject information, comprising: Wherein the distinguishing step, the shape and the relative position and angle of the said acoustic wave detector acoustic reflector portion, obtains the region of the space where imaginary image based on the reflected acoustic waves is obtained, contained in the area the method of analyzing the object information according to claim 8, characterized in that it is determined that the imaginary image by the reflected acoustic wave image to be. Measured multiple times by changing the position or angle of the acoustic reflector,
The analysis of subject information according to claim 8 or 9, further comprising a step of acquiring information images in the subject for each measurement and adding the obtained information images. Method. A computer program for obtaining information on an object in a photoacoustic imaging apparatus including an acoustic wave detection unit and an acoustic reflection unit,
On the computer,
An acquisition step of acquiring a detection signal of the photoacoustic wave, wherein the test body or al emitted by the light irradiated to the subject,
Based on the acquired detection signal , an arithmetic processing step of acquiring an information image in the subject is executed,
The arithmetic processing step includes
A step of pre based on dangerous out signal to obtain the information image by performing reconstruction processing,
Using the relative position and angle of the acoustic reflector portion and the acoustic wave detector, an image contained prior Kijo paper image, the real image based on the direct acoustic wave directly incident to the acoustic wave detector a distinguishing step and imaginary image based on the reflected acoustic waves incident to the acoustic wave detector is reflected to the acoustic reflector portion,
Calculating a real image based on the reflected acoustic wave from a virtual image based on the reflected acoustic wave using a relative position and angle of the acoustic wave detecting unit and the acoustic reflecting unit;
Using the real image based on the previous SL reflected acoustic waves, comprising the steps of: complementing the real image based on the direct acoustic waves,
A computer program comprising:

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