JP2014073411A - Test object information processing apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an imaging apparatus simultaneously acquiring a photoacoustic image and an ultrasonic image and causing no deviation in respective imaging areas, even when respective signals of both images are acquired by individual transducers.SOLUTION: A biological information processing apparatus includes: a first device array 4a for transmitting/receiving elastic waves; a first signal processing section that generates a tomographic image from signals received by the first device array; a light source for applying light to a subject; a second device array 4b for receiving elastic waves generated by the light applied to the subject; and a second signal processing section that generates a stereoscopic image from signals received by the second device array. The first device array transmits/receives the elastic waves obliquely to the subject's surface, where a region in the subject from which the tomographic image is acquired and a region in the subject from which the stereoscopic image is acquired are overlapped.

Description

  The present invention relates to a biological information processing apparatus, and more particularly to a biological information processing apparatus that combines a three-dimensional stereoscopic image using photoacoustic waves and a two-dimensional tomographic image using ultrasonic echoes.

Conventionally, diagnostic imaging apparatuses using ultrasonic waves have been widely used. In a conventional apparatus, a tomographic image is generated by transmitting an ultrasonic wave to a subject, receiving a reflected ultrasonic echo, and imaging it. A three-dimensional stereoscopic image can also be obtained by using a two-dimensional array of electromechanical transducers (transducers) or scanning a one-dimensional array of transducers. In addition, a proposal has been made to display such a three-dimensional stereoscopic image simultaneously with a two-dimensional tomographic image (Patent Document 1).
On the other hand, in the examination of specimens, development of devices that display not only morphological images but also functional images has been promoted in recent years. One of such devices is a device using photoacoustic spectroscopy. This photoacoustic spectroscopic analysis results when a specific substance in the specimen absorbs the energy of the irradiated light when the specimen is irradiated with visible light, near infrared light, or mid-infrared light having a predetermined wavelength. A photoacoustic wave is detected, and the concentration of the specific substance is quantitatively measured. The specific substance in the specimen is, for example, glucose or hemoglobin contained in blood.

  In Patent Document 2, a morphological image and a functional image are displayed by simultaneously acquiring both a photoacoustic image and a normal ultrasonic echo image using a common one-dimensional transducer. The tissue structure obtained by the ultrasound echo method can be displayed in an overlapping manner with the three-dimensional structure of glucose, hemoglobin, and their activities obtained by the photoacoustic imaging method, so that malignant tumors in the tissue can be judged effectively. It is expected. In particular, in a functional image obtained by the photoacoustic imaging method, only a part having a specific function is displayed, so that the visibility during three-dimensional display is good, but it is difficult to determine the position in the body. The ultrasonic echo method is advantageous for site identification because the structure of the entire tissue is shown, and it is effective to display it simultaneously with photoacoustic imaging.

  In this specification, an elastic wave generated by a photoacoustic spectroscopic analysis method (photoacoustic imaging method) is called a photoacoustic wave, and an elastic wave transmitted and received in a normal pulse echo method is called an ultrasonic wave.

JP 2008-229097 A JP 2005-21380 A

In Patent Document 1 that simultaneously displays a two-dimensional tomographic image and a three-dimensional stereoscopic image by the ultrasonic echo method, a functional image cannot be obtained in the first place. In addition, the ultrasonic echo method has an advantage that a soft tissue can be photographed in detail. Therefore, when a stereoscopic image is used, the visibility is inferior. Stereoscopic images obtained by the ultrasonic echo method are useful for observation of parts with clear boundaries, such as the heart and fetus, and multiple parts overlap by forming three-dimensional images when observing parts of multiple tissues where the boundaries are not clear. On the contrary, the visibility may deteriorate. In addition, in order to obtain a stereoscopic image by the ultrasonic echo method, it is necessary to sequentially create a large number of ultrasonic beams and collect ultrasonic echoes for each of them. Therefore, it is difficult to create a fine image with high resolution in a short time.
On the other hand, in the acquisition of a three-dimensional image by the photoacoustic imaging method, three-dimensional image data can be constructed by receiving a photoacoustic wave generated by a single light irradiation with a two-dimensional array transducer. Therefore, in the method of Patent Document 2, the acquisition time does not increase as in the case of acquiring three-dimensional image data by the ultrasonic echo method.

However, in Patent Document 2, since the photoacoustic wave is received, the sound beam is transmitted, and the echo is received by a common transducer, the following problems occur.
The frequency band of the photoacoustic wave used in the photoacoustic spectroscopic analysis method is generally lower than the frequency band of the ultrasonic wave used in the ultrasonic echo. For example, the frequency band of the photoacoustic wave is distributed in the range of 200 KHz to 2 MHz with 1 MHz as the center frequency, which is lower than the center frequency of the ultrasound used in the ultrasonic echo, 3.5 MHz to 12 MHz. Therefore, when both of them are received by a common transducer, there is a problem that the spatial resolution is deteriorated in the ultrasonic image. In Patent Document 2, the harmonic imaging method is applied to cope with this problem, but the harmonic component may be less sensitive than the fundamental component because the signal is attenuated. When the frequency band of the photoacoustic wave and the ultrasonic wave is farther apart (for example, the central band of the photoacoustic wave is about 1 MHz and the central band of the ultrasonic wave is about 10 MHz), the above-mentioned problem is noticeable when received by a common transducer Become.
In addition, as described above, a two-dimensional transducer is required to construct a three-dimensional stereoscopic image by the photoacoustic imaging method at high speed. On the other hand, in order to acquire image data by the ultrasonic echo method in a short time, it is preferable to construct a tomographic image by performing ultrasonic beam scanning on a plane with a substantially one-dimensional array of transducers.

  Thus, since the requirements for the transducer are different between the ultrasonic echo method and the photoacoustic imaging method, it is preferable to use the transducer individually. In this case, there has been a problem that a shift occurs in a region where an actual image is acquired due to a shift in the arrangement of each transducer.

  The present invention has been made in consideration of the above problems, and its purpose is to obtain a three-dimensional stereoscopic image by a photoacoustic imaging method and a two-dimensional tomographic image by an ultrasonic echo method with different transducers. The purpose is to match the shooting areas.

In order to solve the above problems, a biological information processing apparatus according to the present invention provides:
A first element array for transmitting and receiving elastic waves;
A first signal processing unit for generating a tomogram from signals received by the first element array;
A light source for irradiating the subject with light;
A second element array for receiving an elastic wave generated by light irradiated on the subject;
A second signal processing unit that generates a stereoscopic image from signals received by the second element array;
A biological information processing apparatus having
The first element array transmits and receives elastic waves obliquely with respect to the surface of the subject so that a region in the subject from which the tomographic image is obtained and a region in the subject from which the stereoscopic image is obtained overlap. ,
It is characterized by that.

The biological information processing method according to the present invention includes:
Photoacoustics that acquire information in a subject by receiving echo acoustic waves, which are reflected from the subject's elastic wave reflected in the subject, and photoacoustic waves generated from the subject by the light radiated on the subject A biological information processing method in an imaging apparatus,
A tomographic image generating step of irradiating the subject with elastic waves, receiving echo elastic waves reflected from within the subject, and generating a tomographic image of the subject;
A stereoscopic image generating step of irradiating the subject with light, receiving elastic waves generated in the subject, and generating a stereoscopic image of the subject;
Including
In the tomographic image generation step, elastic waves are transmitted and received obliquely with respect to the subject surface so that the region in the subject from which the tomographic image is obtained and the region in the subject from which the stereoscopic image is obtained overlap.
It is characterized by that.

  According to the present invention, the three-dimensional stereoscopic image obtained by the photoacoustic spectroscopy and the imaging region of the ultrasonic tomographic image obtained by the ultrasonic echo method overlap, so that both images can be acquired at the same time for the same subject part. Furthermore, the positional relationship between the inspection target by the photoacoustic imaging method and the surrounding biological tissue can be observed with high accuracy, and the region to be imaged by the photoacoustic spectroscopy can be set while visually recognizing on the tissue tomographic plane.

Block diagram showing a configuration example of a photoacoustic imaging apparatus The figure explaining a photoacoustic probe The figure which shows the probe composition in the case of controlling an ultrasonic scanning surface mechanically The figure which shows the example of the photoacoustic imaging device

<First Embodiment>
[overall structure]
FIG. 1 shows an overall outline of a photoacoustic imaging apparatus (biological information processing apparatus) according to this embodiment. In the photoacoustic imaging apparatus according to the present embodiment, a photoacoustic probe (photoacoustic probe) 100 includes a transducer array 4a for an ultrasonic echo method and a transducer array 4b for a photoacoustic image. Hereinafter, the ultrasonic transducer array 4a and the photoacoustic transducer array 4b are referred to. The ultrasonic transducer array 4a corresponds to the first element array in the present invention, and the photoacoustic transducer array 4b corresponds to the second element array in the present invention.

First, a configuration for generating a tomographic image by the ultrasonic echo method will be described. In order to transmit an ultrasonic wave (elastic wave) from the ultrasonic transducer array 4a, an ultrasonic signal is generated through the system controller 1, the transmission beam former 2, and the transmission amplifier 3, and a voltage is applied to the ultrasonic transducer array 4a. The The transmitted ultrasonic wave is reflected from the subject 14, and the reflected ultrasonic wave (echo elastic wave) is received by the ultrasonic transducer array 4a. The received ultrasonic signals are phased and added to the reception signals from the respective elements through the reception amplifier 5 and the reception beam former 6 that performs delay and weighting control. Then, after being detected and converted into a luminance signal by the ultrasonic signal processing unit (first signal processing unit) 10, it is stored in an image memory in the image processing unit 11.
A linear scanning method can be used for transmission / reception beam forming for creating a tomographic image by the ultrasonic echo method. In the linear scanning method, an ultrasonic beam is formed by the ultrasonic transducer array 4a and is scanned substantially in parallel. For this reason, a part of the transducer group constituting the ultrasonic transducer array 4a is used as an ultrasonic aperture for ultrasonic transmission / reception, and an ultrasonic beam is transmitted / received from the ultrasonic aperture. The transmission beam former 2 and the reception beam former 6 select this ultrasonic aperture, and transmit and receive ultrasonic waves using a plurality of corresponding transducers in the ultrasonic transducer array 4a. By switching the transducer to be selected, the ultrasonic aperture is moved in a one-dimensional direction. That is, the transmission / reception ultrasonic beam can be moved substantially in parallel. An ultrasonic scanning surface 21 (FIG. 2C) is formed by scanning with an ultrasonic beam (linear scanning). The imaging area of the tomographic image by the ultrasonic echo method is this ultrasonic scanning surface 21.
At the same time, the transmission beamformer 2 and the reception beamformer 6 perform an operation called focusing that converges the ultrasonic beam by giving different delays to the transmission / reception signals of a plurality of transducers. Furthermore, it is desirable to perform dynamic focusing and apodization for moving the focus point during the phasing addition of the received signal. However, these are widely known in the technical field, and thus description thereof is omitted. Although details will be described later, in the present embodiment, the ultrasonic scanning surface 21 is configured to be tilted by transmission / reception beam forming processing.

  Next, a configuration for generating a stereoscopic image by photoacoustic spectroscopy will be described. The light source 13 oscillates pulsed laser light for irradiating the subject 14 with a drive signal from the system control unit 1 and irradiates the subject 14. By irradiating the subject 14 with pulsed laser light, the detection target such as hemoglobin inside the subject absorbs the energy of the laser light, and the temperature of the detection target rises according to the amount of absorbed energy. Due to this, the detection target is instantaneously expanded to generate a photoacoustic wave (elastic wave). The generated photoacoustic wave is received by the photoacoustic transducer array 4b, and is re-imaged by the photoacoustic signal processing unit (second signal processing unit) 9 via the reception amplifier 7 and the A / D converter 8. Configuration processing. The reconstructed photoacoustic signal is stored in the image memory in the image processing unit 11 as a luminance signal.

  In the memory of the image processing unit 11, image data of a stereoscopic image (photoacoustic image) and a tomographic image (ultrasonic image) obtained from the photoacoustic signal processing unit 9 and the ultrasonic signal processing unit 10 are stored. In the image processing unit 11, based on the image data and the angle data of the ultrasonic scanning surface 21 from the system control unit 1, a synthesized image obtained by synthesizing a photoacoustic analysis image of a blood vessel and a tissue image by ultrasonic echoes is generated. The image is generated and displayed on the image display unit 12. This display may be, for example, a composite image obtained by superimposing a tomographic image of an ultrasonic echo method on a three-dimensional stereoscopic image by a photoacoustic method, or an ultrasonic wave on a two-dimensional cross-sectional image or a two-dimensional projection image of a photoacoustic method. A composite image in which images are superimposed may be used. Moreover, you may display each image separately.

[Probe configuration]
FIG. 2 shows a probe configuration for simultaneously acquiring a photoacoustic signal and an ultrasonic echo signal. FIG. 2A shows the appearance of the probe, and FIG. 2B is an enlarged view of the transducer portion. FIG. 2C shows the entire configuration of the probe and an imaging region by the photoacoustic method and the ultrasonic echo method.
As shown in FIG. 2A, the probe 100 includes a case 30, a cable 31, and a transducer unit 4. The transducer unit 4 includes the ultrasonic transducer array 4a and the photoacoustic transducer array 4b as described above. As shown in FIG. 2B, the photoacoustic transducer array 4b is two-dimensionally arranged, and is provided with a light irradiation opening 23 for incident pulse laser light. The ultrasonic transducer array 4a has an array (linear) structure in which a plurality of one-dimensional transducer arrays are arranged. Here, the number of elements included in one row of transducers is sufficiently larger than the number of rows. This structure is exactly a two-dimensional array, but can be regarded as a substantially one-dimensional array, and is also called a 1.75-dimensional array type transducer.
The ultrasonic transducer array 4a and the photoacoustic transducer array 4b are arranged side by side in a direction orthogonal to the linear scanning direction of the ultrasonic transducer array 4a. In addition, since the ultrasonic transducer array 4a has a plurality of transducer arrays, the beam can be tilted in the direction perpendicular to the linear scanning direction by the beam forming process, and the ultrasonic beam is transmitted / received obliquely with respect to the subject surface. it can.
It should be noted that the upper surface and the lower surface of the transducer array are matched layers, backing, wiring,
An acoustic lens is disposed on the upper surface of the ultrasonic transducer array, but is omitted from the drawing.

  The overall configuration of the probe will be described with reference to FIG. 2C. In the probe 100 according to the present embodiment, an ultrasonic transducer array 4 a, a photoacoustic transducer array 4 b, light incident prisms 16 a and 16 b, and an optical transmission path 17 are formed on the protective plate 15. A semitransparent mirror film 18 and a total reflection mirror film 19 are formed in the optical transmission line 17. The pulse laser beam generated from the light source 13 propagates through the optical transmission path 17, and a part, preferably half of the light amount thereof is reflected by the translucent mirror film 18, passes through the protective plate 15 by the light incident prism 16 a, and passes through the subject 14. Is irradiated. Further, the pulsed laser light transmitted through the semitransparent mirror film 18 in the optical transmission path 17 is reflected by the total reflection mirror film 19, passes through the protective plate 15 by the light incident prism 16 b, and is irradiated onto the subject 14. The optical transmission line 17 only needs to transmit the pulse laser beam without loss, and can be formed using an optical fiber bundle or a glass block material. In the case of being formed of a glass block material, the semitransparent mirror film 18 and the total reflection mirror film 19 can be formed by a multilayer thin film that matches the wavelength of the pulse laser beam on the block bonding surface and the end surface. Furthermore, the optical transmission path 17 can be configured to propagate the pulsed laser light in space, and the semitransparent mirror film 18 and the total reflection mirror film 19 can be configured using a semitransparent mirror and a total reflection mirror. In this case, the optical transmission line 17 may be enclosed by a lens barrel that is separated from the outside. The light incident prisms 16a and 16b can also be made of a glass block material, but it is also possible to obtain an equivalent effect by substituting a total reflection mirror. Further, when the optical transmission path 17 is constituted by an optical fiber bundle, it is possible to irradiate the subject 14 with pulsed laser light directly from the optical transmission path 17 by using the plasticity of the optical fiber bundle.

In the present embodiment, the irradiation pulse laser light is incident on the subject 14 from the light irradiation opening 23 around the photoacoustic transducer array 4b. The pulsed laser light is obliquely incident on the subject 14 by the light incident prisms 16a and 16b, and is irradiated so as to intersect just below the photoacoustic transducer array 4b. The portion irradiated with the pulse laser beam (the portion in front of the photoacoustic transducer array 4b) is a photoacoustic imaging region 20 where a stereoscopic image is captured by photoacoustic spectroscopy. This configuration has an advantage that the photoacoustic imaging region 20 below the photoacoustic transducer array 4b can be irradiated with a substantially uniform light amount.
When the subject 14 is thin, a configuration in which a pulse laser is incident on the subject 14 from the side opposite to the photoacoustic transducer array 4b may be employed. Moreover, the intensity of light irradiation in the thickness direction of the subject 14 can be made uniform by performing double-sided irradiation on the subject 14 opposite to the photoacoustic transducer array 4b side. However, when the subject 14 is thick, it is difficult for the pulse laser light to pass through the subject 14, so that the pulse laser light incidence from at least the photoacoustic transducer array 4b side is a preferable form as in this configuration.

  The ultrasonic transducer array 4a transmits an ultrasonic beam and simultaneously receives a reflected wave of the beam in the subject 14 as an ultrasonic echo signal. In addition, directivity can be given to the received beam by performing beam forming processing on the received ultrasonic wave. The ultrasonic transmission / reception beam is scanned in the scanning direction (in FIG. 2C, the direction perpendicular to the paper surface). Thereby, a tomographic image of the subject 14 on the ultrasonic scanning surface 21 is obtained. That is, the ultrasonic scanning surface 21 is an imaging region (imaging cross section) by an ultrasonic echo method. In addition, it is preferable to provide an ultrasonic stand-off 29 for satisfactorily taking a tomographic image by inclining an ultrasonic beam with respect to the surface of the subject and entering the subject 14.

[Operation of ultrasonic transducer array]
As described above, in this embodiment, the direction of the ultrasonic beam transmitted / received from the ultrasonic transducer array 4a can be tilted in the direction perpendicular to the scanning direction (the left-right direction in FIG. 2C) by the transmission / reception beamformer. For this purpose, the ultrasonic transducer array 4a has a plurality of transducer rows. Hereinafter, beam steering processing for tilting the beam direction will be described.

  As described above, the ultrasonic transducer array 4a has transducer groups arranged in a matrix. For the sake of explanation, the ultrasonic beam scanning direction (direction perpendicular to the paper surface in FIG. 2C; corresponding to the first direction of the present invention) is the lateral direction, and the vertical direction (left and right direction in FIG. 2C; second direction of the present invention). Is called the elevation direction. The ultrasonic beam scanning is performed by moving the ultrasonic aperture in the lateral direction. The transmission beamformer 2 and the reception beamformer 6 perform beam scanning by selecting a transducer that forms an ultrasonic aperture.

  At this time, the transmission beam is steered in the element direction having a relatively small amount of delay time by inputting a transmission signal having different delay times between the transducers arranged in the elevation direction. The steering tilt amount, that is, the transmission / reception direction of the ultrasonic beam in the plane orthogonal to the linear scanning direction is controlled by the relative amount of delay time. The steering tilt amount can be specified by the user from an input unit (not shown). Therefore, the user can adjust the inclination of the tomographic image acquisition surface to a desired angle while viewing the acquired image.

  Similarly, by giving different delay times between the transducers arranged in the elevation direction with respect to the received signal output from the transducer, the received beam is steered in the direction of the element having a relatively small amount of time delay in the phasing addition. Is done. The amount of steering tilt is controlled by the relative amount of delay time. Further, as is well known in the art, the transmission / reception beam is focused by delaying the signal between the transducers in the ultrasonic aperture.

  By scanning the ultrasonic beam inclined in the elevation direction in the lateral direction in this way, the inclination of the ultrasonic scanning surface 21 is controlled, and the imaging cross section by the ultrasonic echo method crossing the photoacoustic imaging region 20 is changed. Can do.

  The ultrasonic transducer array 4a in the present embodiment is also characterized by the above-described operation. The term 1.75 dimensional array is not only a simple transducer array but also an expression including its driving method. That is, transducer arrays having the same or almost the same number of vertical and horizontal elements may be used as the ultrasonic transducer array. In this case, the ultrasonic aperture is one-dimensionally moved to create a tomographic image at this angle while keeping the angle formed by the normal of the transducer transmission / reception surface and the ultrasonic beam at the specified angle. It may be configured to scan linearly. In general, it is desirable that the number of elements in the scanning direction is large in order to increase the width of the screen, but the number of elements for tilting (steering) the ultrasonic beam may be smaller. Therefore, in terms of cost, it is preferable to use a transducer array having different vertical and horizontal element arrangements in terms of form.

[Operation of Photoacoustic Transducer Array]
The photoacoustic transducer array 4b is a transducer group arranged in a two-dimensional array in form. However, unlike the ultrasonic transducer array 4a, scanning of a beam such as selecting an element for providing an opening for receiving a photoacoustic wave and moving the opening is not performed. The photoacoustic transducer array 4b uses reception signals from almost all elements at all times during reception for constructing a stereoscopic image. Also, ultrasonic waves are not transmitted. The photoacoustic waves from the desired three-dimensional imaging region generated by the light irradiation are received almost simultaneously by the respective elements of the photoacoustic transducer array 4b except for the difference in the propagation time thereof. A 3D stereoscopic image is constructed using the signal. For this reason, photoacoustic wave signal acquisition is performed instantaneously.
In the present invention, the photoacoustic transducer array 4b that can collectively acquire signals for a three-dimensional stereoscopic image and the ultrasonic transducer array 4a that is required to perform transmission / reception beam scanning for creating a tomographic image are separately provided. doing. Furthermore, the angle of the ultrasonic scanning surface formed by the ultrasonic transducer array 4a can be controlled in order to suitably combine both captured images.

[Transducer characteristics]
In addition to the above operational differences, the ultrasonic transducer array 4a and the photoacoustic transducer array 4b have the following characteristic differences.
Since the ultrasonic transducer array 4a is used for the purpose of rendering morphological information inside the specimen, it is composed of transducers that can transmit and receive ultrasonic waves at a higher frequency than the photoacoustic transducer that acquires functional information. Here, the frequency band of the ultrasonic transducer array 4a is typically about 7 to 12 MHz. Further, the form information is information based on the form inside the specimen, and is information obtained by a normal ultrasonic pulse echo method. Further, in order to perform transmission / reception of ultrasonic waves in the ultrasonic transducer array 4a, it is necessary to use a transducer that satisfies both the characteristics of reception and transmission of ultrasonic waves at the same time. For example, an element having a high SNR for reception and having durability against a high voltage applied at the time of transmission is required, which limits the selection of transducers.

On the other hand, since the photoacoustic transducer array 4b is used for the purpose of depicting the functional information inside the specimen, the transducer can receive ultrasonic waves (photoacoustic waves) having a frequency lower than that of the ultrasonic transducer for acquiring the morphological information. Consists of Here, the frequency band of the photoacoustic transducer array 4b is typically about 1 to 4 MHz. The function information is information obtained by a photoacoustic spectroscopic analysis method (photoacoustic imaging method), for example, information on the concentration of a specific substance in a specimen such as glucose or hemoglobin contained in blood. In order to acquire such functional information, a high SNR is required for the photoacoustic signal. However, a transducer specialized in a high SNR at the time of reception by separating it from an ultrasonic transducer that performs transmission and reception as in this embodiment. This has the advantage that it can be selected.
For example, as a transducer constituting the ultrasonic transducer array 4a, a piezoelectric element that performs mutual conversion between an electrical signal and mechanical vibration (ultrasonic waves) is used. On the other hand, any detector may be used as the transducer constituting the photoacoustic transducer array 4b as long as it can detect acoustic waves. For example, a transducer using a piezoelectric phenomenon, a transducer using optical resonance, a transducer using a change in capacitance, and the like can be given. Of these, a transducer having a high reception SNR may be used according to the application. For example, when receiving acoustic waves generated from detection objects of various sizes, it is possible to use a transducer that uses a change in capacitance in a wide detection frequency band or a plurality of transducers that have different detection bands.

[Probing method]
The probe 100 according to the present embodiment can be manufactured as follows, for example. First, an ultrasonic transducer array 4a (one-dimensional array transducer) and a photoacoustic transducer array 4b (two-dimensional array transducer) are produced by a method similar to the conventional method. This is performed by cutting out the piezoelectric vibrator, adhering to the backing material, dicing the vibrator, attaching the acoustic matching layer, and pulling out the wiring portion. An acoustic lens is attached to the ultrasonic transducer. Then, the ultrasonic transducer array 4a and the photoacoustic transducer array 4b are arranged with a space therebetween, and then fixed with a mold. And it is completed by fitting in the housing.
Separately created ultrasonic transducer array 4a (one-dimensional array transducer) and photoacoustic transducer array 4b (two-dimensional array transducer) may be arranged in parallel.

[Advantages of this embodiment]
According to the present embodiment, since a three-dimensional stereoscopic image by the photoacoustic method and a two-dimensional tomographic image by the ultrasonic echo method can be acquired simultaneously, the position in the tissue of the specific structure included in the functional image by the photoacoustic method is determined. It can be confirmed by the tomographic image obtained by the ultrasonic echo method that can obtain the structure of the whole tissue.
In addition, since the transducer array for the photoacoustic method and the transducer array for the ultrasonic echo method are individually provided, elements suitable for the respective conditions can be employed. Therefore, an image by the photoacoustic method and an image by the ultrasonic echo method can be taken under good conditions, and thus a good image can be obtained.
Furthermore, since the imaging region by the photoacoustic method and the imaging region by the ultrasonic echo method overlap, it is possible to capture both images at the same time and display an image synthesized in real time. Further, even if time-division imaging is performed in order to avoid signal interference, the same part can be imaged at substantially the same timing. If both imaging areas are different, in order to obtain an image by the both methods at the same location, it is necessary to move the probe and re-image, and information at the same time cannot be obtained.
In addition, since the angle of the ultrasonic tomogram (inclination of the ultrasonic beam) can be controlled, the user can select a cross-section of the tissue structure as a reference. For this reason, by selecting a cross-section from which a characteristic form in the subject can be extracted and displaying a tomographic image, it is possible to specify a favorable region when setting the photoacoustic analysis region. In addition, the cross-section of the ultrasound image can be changed when observing the tissue structure by photoacoustic analysis and ultrasonic echoes in the subject, allowing comparison of the photoacoustic analysis features and tissue structure over a wide range of sections. It becomes.

<Second Embodiment>
In the first embodiment, the ultrasonic transducer array 4a is configured to include a plurality of transducer arrays, and the configuration is such that the inclination of the ultrasonic scanning surface is controlled by providing a delay time between elements in the elevation direction. In the present embodiment, the ultrasonic transducer array 4a is mechanically tilted.
FIG. 3 shows a configuration for tilting the ultrasonic transducer array in the present embodiment. The ultrasonic transducer array 4 a is supported by a support arm 26, and the support arm 26 can be rotated by a rotation motor (not shown) through a rotation shaft 27. A rotation sensor is attached to the rotation motor, and the rotation angle of the rotation shaft 27 is measured. The rotation motor and the rotation sensor are connected to the system control unit 1. The rotation motor is driven by a drive signal from the system control unit 1, and at the same time, an inclination angle information signal of the support arm 26 is transmitted to the system control unit 1 by the rotation sensor. The system control unit 1 can detect the tilt angle of the support arm 26 based on the tilt angle information signal and simultaneously drive the rotation motor with a drive signal to set the tilt angle of the support arm 26 to a desired angle. The support arm 26, the rotation shaft 27, the rotation sensor, and the rotation motor correspond to the rotation mechanism in the present invention.
With the above operation, the inclination of the ultrasonic transducer array 4a in the elevation direction can be set to a desired angle. The ultrasonic transducer array 4a, the support arm 26, and the rotating shaft 27 are stored in a packaging material 24 filled with oil 25 that propagates ultrasonic waves without attenuation. An ultrasonic matching layer 28 is preferably formed on the surface of the packaging material 24 in contact with the subject 14 so as to transmit the ultrasonic waves without reflecting them.
In this configuration, by controlling the inclination of the ultrasonic transducer array 4a itself, the angle of the ultrasonic beam can be changed, and the crossing angle between the ultrasonic scanning surface 21 and the photoacoustic imaging region 20 can be changed. No forming process is required. For this reason, the transducers in the transducer array 4a can have a one-dimensional one-dimensional structure, and the number of transducers and their signal lines can be reduced. Further, since the transmission beam former 2 and the reception beam former 6 do not require ultrasonic beam steering, there is an advantage that the circuit configuration scale of each beam former can be made smaller than that of the above-described embodiment. However, when the transducers of the transducer array 4a are arranged in one row, it is desirable to focus the ultrasonic beam in the elevation direction by providing the acoustic lens 22 on the transmission / reception surface of the transducer array 4a.
In order to obtain a desired scanning section angle, mechanical steering control of the transducer array surface and beam steering based on signal delay control between elements may be combined.

  An embodiment of a three-dimensional photoacoustic imaging apparatus using the present invention will be described with reference to FIG. The subject 14 is held between two protective plates 15. A probe 100 and a guide support (guide part) 32 are arranged on the protection plate 15. The probe unit is moved along the guide support 32 by a stepping line motor (moving unit) (not shown). The probe 100 is connected to the main body 33 by a cable 31. The stepping line motor is driven by a drive signal from the system controller 1 in the main body 33. The main body 33 includes the system control unit 1, the transmission amplifier 3, the transmission beam former 2, the reception amplifiers 5 and 7, the reception beam former 6, A / D 8, the photoacoustic signal processing unit 9, and the ultrasonic signal processing unit shown in FIG. 2C. 10, an image processing unit 11, an image display unit 12, and the like are stored. The main body 33 also includes a console 43 for performing operation input.

  The pulsed laser light source 13 may be provided in the probe 100, or a laser beam that is disposed outside and generated may be guided to the probe 100 through a transmission path (not shown). The ultrasonic transducer array 4 a in the probe 100 is arranged such that the lateral direction is perpendicular to the direction along the guide support 32 and the elevation direction is parallel to the direction along the guide support 32. Therefore, the movement of the probe portion is regulated in the elevation direction by the guide support tool 32. The image display unit 12 includes a photoacoustic image display unit 42 that displays a photoacoustic analysis image and an ultrasonic image display unit 41 that displays a tomographic image of a tissue by an ultrasonic echo method.

The ultrasonic transducer array 4a in the probe 100 transmits / receives an ultrasonic beam while scanning it in the lateral direction, creates a tomographic image of the tissue by ultrasonic echoes in the main body 33 as described above, and creates the image display unit 12 in real time. Is displayed on the ultrasonic image display unit 41. The user preferably adjusts the angle of the ultrasonic scanning surface 21 through the console 43 according to the thickness of the subject 14 so that the tomographic plane of the ultrasonic tomography includes the entire width of the photoacoustic imaging region 20. At this time, it is possible to adjust the position of the imaging section with reference to the ultrasonic tomographic image displayed in real time.
Next, the pulse laser light source is driven by the drive signal from the system control unit 1, and the subject 14 is irradiated with the pulse laser light from the light aperture in the probe 100. At the same time, the photoacoustic signal is acquired by the photoacoustic transducer array 4b. Is called. Using the acquired photoacoustic signal, photoacoustic analysis image data is created in the procedure described above in the main body 33, and a three-dimensional stereoscopic photoacoustic image is created by the image processing unit 11, and the image display unit 12 Are displayed on the photoacoustic image display unit 42. The image displayed on the photoacoustic image display unit 42 is a composite image obtained by superimposing a tomographic image by an ultrasonic echo method on a three-dimensional stereoscopic photoacoustic image, or a photoacoustic two-dimensional cross-sectional image, a two-dimensional projection image, It may be a composite image superimposed with an ultrasonic image. Further, the image displayed on the photoacoustic image display unit 42 may be an image obtained by joining captured images of different parts of the subject 14 obtained from the probe 100 moved along the guide support 32.

This embodiment has an advantage that a photoacoustic analysis image can be acquired over a wide area of the subject 14 by moving the probe 100 in a direction along the guide support 32 and a part or all of the image can be displayed. At this time, an ultrasonic tomographic image intersecting with the photoacoustic imaging region 20 is simultaneously acquired and displayed in real time, so that the user can move the probe 100 while checking the region in the subject 14 to be imaged by the probe 100. That is, it is possible to specify the imaging position and imaging range of the photoacoustic analysis of the probe 100 while viewing the ultrasonic image of the ultrasonic image display unit 41, and the photoacoustic analysis is performed using the tissue structure in the subject based on the ultrasonic image as an index. The imaging range can be determined. Furthermore, since the angle of the tomographic plane of the ultrasonic image can be adjusted, the cross-section of the reference tissue structure can be selected. Therefore, it is possible to select a cross section from which a characteristic form can be extracted with respect to the structure in the subject 14 and display an ultrasonic tomographic image of the cross section, which is favorable when a photoacoustic analysis region is set using an ultrasonic image. The area can be specified. In addition, since the cross section of the ultrasonic screen can be changed when the photoacoustic analysis feature in the subject 14 and the observation of the tissue structure by the ultrasonic echo are performed with the synthesized image, the photoacoustic analysis feature and the tissue can be changed over a wide range. The structure can be compared.

In the above description, the photoacoustic image is a three-dimensional stereoscopic image, and the ultrasonic image is a two-dimensional tomographic image. However, a three-dimensional stereoscopic image by an ultrasonic echo method may be created and displayed. A three-dimensional stereoscopic image by the ultrasonic echo method can be created by synthesizing a plurality of ultrasonic tomographic images acquired by the probe 100 moving along the guide support 32 according to the position of the probe 100. Even in such a case, since the photoacoustic imaging region 20 and the ultrasonic scanning surface 21 overlap each other, the following effects are produced. That is, since the photoacoustic image and the ultrasonic image overlap in the moving direction, the non-displayable area of the composite image caused by the shift of both images is reduced with respect to the moving amount of the probe 100, and the moving amount of the probe 100 is reduced. The entire apparatus can be configured compactly.
In the above embodiment, the movement of the probe 100 is one-dimensional. However, by combining this linear movement in a raster shape, the probe 100 is moved two-dimensionally on the subject 14 to perform a wider range of photoacoustic imaging. Can be created.

4a Ultrasonic transducer array 4b Photoacoustic transducer array 9 Photoacoustic signal processing unit 10 Ultrasonic signal processing unit 13 Light source 14 Subject

The present invention relates to a subject information processing apparatus, and more particularly to a subject information processing apparatus that combines a three-dimensional stereoscopic image using photoacoustic waves and a two-dimensional tomographic image using ultrasonic echoes.

In order to solve the above problems, a subject information processing apparatus according to the present invention includes:
A first element array for transmitting and receiving elastic waves;
First signal processing means for generating a tomogram from signals received by the first element array;
A light source for irradiating the subject with light;
A second element array for receiving an elastic wave generated by light irradiated on the subject;
Second signal processing means for generating a stereoscopic image from signals received by the second element array;
Moving means for moving the first element array and the second element array;
A subject information processing apparatus comprising:
The first element array, as a region within a subject that region and the three-dimensional image inside the object where the tomographic image is obtained are obtained overlap, to send and receive acoustic waves,
The moving means moves the first element array and the second element array so that an area in the subject from which the tomographic image is obtained and an area in the subject from which the stereoscopic image is obtained overlap. It is characterized by that.

Claims (8)

A first element array for transmitting and receiving elastic waves;
A first signal processing unit for generating a tomogram from signals received by the first element array;
A light source for irradiating the subject with light;
A second element array for receiving an elastic wave generated by light irradiated on the subject;
A second signal processing unit that generates a stereoscopic image from signals received by the second element array;
A biological information processing apparatus having
The first element array transmits and receives elastic waves obliquely with respect to the surface of the subject so that a region in the subject from which the tomographic image is obtained and a region in the subject from which the stereoscopic image is obtained overlap. ,
A biological information processing apparatus. By scanning an elastic wave transmitted from the first element array, a tomographic image on the scanning plane is obtained.
The biological information processing apparatus according to claim 1, wherein the scanning plane overlaps a region of a subject irradiated with light from the light source. The first element array includes a plurality of transducers arranged in at least a first direction,
The second element array is composed of a plurality of transducers arranged two-dimensionally,
The first element array and the second element array are provided side by side in a second direction orthogonal to the first direction,
The first element array transmits and receives an elastic wave inclined in the second direction.
The biological information processing apparatus according to claim 1 or 2, characterized in that The first element array has a two-dimensional arrangement in which a plurality of transducers are arranged in the second direction,
By varying the delay time given to the transducers arranged in the second direction, it is possible to control the angle of inclination of the elastic wave transmission / reception direction in the second direction,
The biological information processing apparatus according to claim 3. A rotation mechanism that rotates the first element array around the first direction as a rotation axis;
By rotating the first element array by the rotation mechanism, it is possible to control the inclination angle of the elastic wave transmission / reception direction to the second direction.
The biological information processing apparatus according to claim 3. A probe unit including at least the first element array and the second element array;
A guide part for restricting movement of the probe part in the second direction;
A moving part for moving the probe part along the guide part;
The biological information processing apparatus according to claim 3, further comprising: The display apparatus which further displays a tomographic image generated by the first signal processing unit and a stereoscopic image generated by the second signal processing unit in an overlapping manner. The biological information processing apparatus according to any one of the above. Biological information for acquiring information in a subject by receiving an echo elastic wave reflected by the subject in the subject's elastic wave and a photoacoustic wave generated from the subject by the light applied to the subject A biological information processing method in a processing apparatus,
A tomographic image generating step of irradiating the subject with elastic waves, receiving echo elastic waves reflected from within the subject, and generating a tomographic image of the subject;
A stereoscopic image generating step of irradiating the subject with light, receiving a photoacoustic wave generated in the subject, and generating a stereoscopic image of the subject;
Including
In the tomographic image generation step, elastic waves are transmitted and received obliquely with respect to the subject surface so that the region in the subject from which the tomographic image is obtained and the region in the subject from which the stereoscopic image is obtained overlap.
A biological information processing method.

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