JP2015123345A - Subject information acquisition device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a technique for preventing prolonged measurement while suppressing the cost in photoacoustic measurement where a light irradiation position is movable.SOLUTION: A subject information acquisition device comprises an irradiation section 3 for irradiating light a subject with light, a scanning control unit 11 for moving the irradiation unit 3 on the subject more than one time, a receiver 9 for receiving an acoustic wave generated from the subject by the irradiation of light from the irradiation unit 3 and converting it to an electric signal, and a processor 12 for generating characteristic information on the inside of the subject by using the electric signal output by the receiver 9. The scanning control unit 11 moves the irradiation unit 3 so that the regions on the subject to be irradiated with light in every more than one time of movement have an at least partially common region. The processing unit 12 generates the characteristic information by using the electrical signals output by the receiver in every more than one time of the movement where the position relationship between the irradiation unit 3 and the receiver 9 is different.

Description

  The present invention relates to a subject information acquisition apparatus.

  One method for obtaining optical characteristic values such as absorption coefficient in a subject such as a living body is photoacoustic tomography (PAT) (Non-patent Document 1). PAT is a technology that utilizes the characteristics of ultrasonic waves that are less scattered in vivo than light.

  In PAT, when pulsed light generated from a light source is irradiated on a living body, the light propagates while diffusing in the living body. The light absorber included in the living body absorbs the propagated light and generates a photoacoustic wave (typically, an ultrasonic wave). By receiving this photoacoustic wave with a probe and analyzing the received signal, it is possible to acquire an initial sound pressure distribution caused by the light absorber in the living body. The absorption coefficient distribution can be acquired by considering the light distribution with respect to the initial sound pressure distribution.

  In order to accurately know the size of the tumor in the living body, it is preferable that the resolution of the apparatus is high. Therefore, in Patent Document 1, an example in which the resolution in a plane parallel to the scanning plane of the probe is improved by disposing two probes on both sides of the light irradiating the living body with inclination relative to the living body. Is disclosed. Further, Patent Document 1 discloses an example in which the resolution is improved by alternately arranging one probe on both sides of light that irradiates a living body for each step.

JP 2012-223567 A

M.M. Xu, L .; Wang "Photoacoustic imaging in biomedicine", Review of scientific instruments, 77, 041101 (2006)

  However, when considering an apparatus such as that disclosed in Patent Document 1, two probes are required, which causes a problem that the apparatus becomes expensive. Further, when one probe is alternately arranged on both sides of the light for irradiating the living body for each step, the imaging time becomes long, which causes a problem that the operator and the subject are burdened.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a technique for preventing prolonged measurement while suppressing costs in photoacoustic measurement in which the irradiation position of light is movable. is there.

The present invention employs the following configuration. That is,
An irradiation unit for irradiating the subject with light; and
A scanning control unit for moving the irradiation unit on the subject a plurality of times;
A receiving unit that receives an acoustic wave generated from the subject by irradiation of light from the irradiation unit and converts the acoustic wave into an electrical signal;
A processing unit that generates characteristic information inside the subject using the electrical signal output by the receiving unit;
Have
The scanning control unit is configured to move the irradiation unit such that a region on the subject irradiated with light in each of the plurality of movements has at least a partially common region;
The processing unit generates the characteristic information using an electrical signal output by the receiving unit for each of the plurality of movements in which the positional relationship between the irradiation unit and the receiving unit is different. This is a specimen information acquisition apparatus.

The present invention also employs the following configuration. That is,
An irradiation unit for irradiating the subject with light; and
A scanning control unit for moving the irradiation unit on the subject a plurality of times;
A receiving unit including a plurality of elements that receive an acoustic wave generated from the subject by irradiation of light from the irradiation unit and convert it into an electrical signal;
A processing unit that generates characteristic information inside the subject using the electrical signal output by the receiving unit;
Have
The receiving unit selects a receiving element group to be used for reception from the plurality of elements so that the elements that receive the acoustic wave in each of the plurality of movements are at least partially different.
The processing unit generates the characteristic information using an electrical signal output by the receiving unit for each of the plurality of movements in which the positional relationship between the irradiation unit and the receiving element group of the receiving unit is different. An object information acquiring apparatus characterized by the above.

  According to the present invention, in photoacoustic measurement in which the irradiation position of light is movable, it is possible to prevent measurement from being prolonged while suppressing cost.

Configuration diagram of Embodiment 1 Flowchart of imaging in Embodiment 1 The figure for demonstrating the effect of Embodiment 1 The figure for demonstrating the effect of Embodiment 1 Configuration diagram of Embodiment 2 Flow chart of imaging in embodiment 2 Configuration diagram of Embodiment 3 First table in the third embodiment Flowchart of imaging in Embodiment 3 Configuration diagram of Embodiment 4 Flowchart of imaging in embodiment 4 Configuration diagram of Embodiment 5 Second table in the fifth embodiment Flowchart of imaging in embodiment 5 Configuration diagram of Embodiment 6 Third table in the sixth embodiment Flow chart of imaging in embodiment 6 The figure for demonstrating the effect of Embodiment 6

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

  The subject information acquisition apparatus of the present invention utilizes photoacoustic tomography technology that irradiates a subject with light (electromagnetic waves) and receives (detects) an acoustic wave generated and propagated in the subject according to the photoacoustic effect. Including equipment. Such an object information acquiring apparatus obtains image data inside the object based on photoacoustic measurement, and thus can be called a photoacoustic image apparatus. In the following description, such a photoacoustic image apparatus and a photoacoustic image forming method using the same will be described. However, the apparatus according to the present invention is not necessarily required to display the characteristic information, and may be stored as usable data.

  Characteristic information or subject information refers to the source distribution of acoustic waves generated by light irradiation, the initial sound pressure distribution in the subject, or the optical energy absorption density distribution, absorption coefficient distribution, and tissue derived from the initial sound pressure distribution. The concentration distribution of the constituent substances is shown. The substance constituting the tissue is, for example, a blood component such as an oxygen saturation distribution or an oxidized / reduced hemoglobin concentration distribution, or fat, collagen, moisture, and the like.

  The acoustic wave referred to in the present invention is typically an ultrasonic wave and includes an elastic wave called a sound wave or an acoustic wave. An acoustic wave generated by the photoacoustic effect is called a photoacoustic wave or an optical ultrasonic wave. An electric signal converted from an acoustic wave by the probe is also called an acoustic signal.

  The present invention can also be understood as an operation method and a control method of a subject information acquisition apparatus. The present invention can also be understood as a program for causing an information processing apparatus or the like to execute an operation method or a control method.

[Embodiment 1]
First, a basic embodiment will be described.

<Photoacoustic imaging device>
The photoacoustic image apparatus of this embodiment is typically shown in FIG. The apparatus has, as a hardware configuration, a pulse light source 1, an optical transmission unit 2, a light irradiation unit 3 that irradiates light to the subject, a holding member 5 that holds the subject, and reception that receives photoacoustic waves generated in the subject. It has a section (probe) 9. The apparatus further includes an image forming unit 12 that forms an image of information in the subject using a signal received by the receiving unit, a display unit 13 that displays information formed by the image forming unit, and a light irradiation unit and a receiving unit. A scanning control unit 11 that controls scanning is included.

  The pulsed light emitted from the pulse light source is transmitted to the light irradiation unit by the light transmission unit. The transmitted pulsed light is applied to the subject held by the holding member through the holding member. The irradiated pulsed light diffuses and propagates inside the subject. When part of the energy of the propagated light is absorbed by a light absorber such as blood (resulting in a sound source), photoacoustic waves (typically ultrasound) are generated due to the thermal expansion of the light absorber. To do.

  The photoacoustic wave generated in the subject is received by the receiving unit through the holding member. The light irradiation unit and the receiving unit may be arranged so as to sandwich the subject or may be arranged on the same side with respect to the subject. The light irradiation unit and the receiving unit move on the subject along the holding member, and the positional relationship is controlled by the scanning control unit. The signal received by the receiving unit is sent to the image forming unit to form an image. Information inside the subject formed with an image is sent to the display unit and displayed.

(Pulse light source)
When the subject is a living body, the light irradiation unit emits light having a wavelength that is absorbed by a specific component among components constituting the living body. The wavelength of light used in the present invention is desirably a wavelength at which light propagates to the inside of the subject. Specifically, when the subject is a living body, the thickness is 600 nm or more and 1100 nm or less. In order to efficiently generate photoacoustic waves, the pulse width is preferably about 10 to 50 nanoseconds.

  As the light source, a laser capable of obtaining a large output is preferable, but a light emitting diode, a flash lamp, or the like can 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 timing, waveform, intensity, etc. of irradiation are controlled by the light source controller. The light source control unit may be integrated with the light source.

(Optical transmission part)
As the optical transmission unit, spatial transmission using a lens, a mirror, and a diffusion plate, transmission using an optical fiber, or a combination of these may be considered.

(Light irradiation part)
The light irradiation unit moves along the holding member. The positional relationship with the receiving unit and the scanning method are controlled by the scanning control unit described below. In order to make the shape of the light irradiated to the subject appropriate, the light irradiation unit may include an optical member such as a lens.

(Subject and light absorber)
These are not constituent elements of the photoacoustic image apparatus of the present invention, but are objects to be measured. The photoacoustic imaging apparatus of the present invention is mainly intended for imaging of blood vessels, diagnosis of malignant tumors and vascular diseases of humans and animals, and follow-up of chemical treatment. The light absorber inside the subject has a relatively high absorption coefficient in the subject although it depends on the wavelength of light used. Specific examples include water, fat, protein, oxygenated hemoglobin, and reduced hemoglobin.

(Receiver)
The receiving unit includes an element that receives photoacoustic waves generated on the surface of the living body, the inside of the living body, and the like by pulsed light and converts them into an analog electric signal. Such a receiving unit is generally called a probe. The receiving unit may also include a plurality of elements. Among a plurality of elements included in the receiving unit, a group of elements that receive an acoustic wave in a certain measurement or scanning is called a receiving element group. In other words, some of the elements in the receiving unit may or may not receive acoustic waves for some reason.

  Various receivers can be used as long as they can receive photoacoustic waves, such as those using piezoelectric phenomena, those using light resonance, and those using changes in capacitance. . As the receiving unit of the present embodiment, a probe in which a plurality of receiving elements are typically arranged one-dimensionally or two-dimensionally is suitable. By using such a multidimensional array element, photoacoustic waves can be received simultaneously at a plurality of locations, and the measurement time can be shortened. When the number of elements of the probe is sufficiently large, scanning can be performed while selecting and switching an arbitrary element by the switching unit.

(Holding member)
In order to acoustically couple the probe and the subject, a material having an acoustic impedance close to that of the subject is preferable as the holding member. An example is polymethylpentene. In order to efficiently receive the photoacoustic wave, it is preferable that the probe and the holding member are brought into contact with each other via an acoustic matching agent such as a liquid such as water or a gel.

  When holding the object between two holding members and irradiating light on the surface of the object opposite to the probe, one holding member does not need to consider acoustic impedance and transmits light. Therefore, any material that is optically transparent may be used. Typically, a plastic plate such as acrylic or a glass plate is used. Of the two holding members, if the holding member with the probe is fixed to the breast, and the holding member with the light irradiation part is movable independently of the light irradiation part, the breast or the like It becomes easy to press the subject.

(Scanning control unit)
The scanning control unit is means for moving the light irradiation unit and the probe with respect to the subject. The scanning control unit includes a scanning mechanism that drives the stage, and the light irradiation unit and the probe move on the scanning mechanism. The scanning control unit enables the photoacoustic measurement while taking the image at an arbitrary position and moving the light irradiation unit and the probe two-dimensionally on the subject.

  In the following description, it is assumed that the scanning control unit moves the light irradiating unit and the probe a plurality of times when scanning with the two points on the subject connected in a substantially straight line is defined as one movement. . That is, the scanning control unit acquires an acoustic wave from a wide area on the subject by a plurality of movements such as reciprocal scanning at substantially the same position or a combination of main scanning and sub scanning.

  The control performed by the scanning control unit in the present invention includes a first scanning mode in which scanning is performed while maintaining the first positional relationship between the light irradiation unit and the receiving unit, and a second position different from the first positional relationship. And a second scanning mode for scanning while maintaining the relationship. The first and second positional relationships and the first and second scanning modes will be specifically described in the embodiment.

(Image forming part)
The image forming unit generates information inside the subject using a signal received by the probe. Typically, a workstation or the like is used for the image forming unit, and the image forming process is performed by software programmed in advance. In some of the embodiments of the present invention, the image forming unit determines whether the signal received by the probe is used for image formation based on the position where the probe receives the photoacoustic wave and the position where the image is formed. To decide. Details will be described in the embodiment.

(Display section)
The display unit is a device that displays data output from the image forming unit. Typically, a liquid crystal display or the like is used. The display unit is not essential for the photoacoustic image apparatus of the present invention, and may be provided separately.

<Detailed explanation>
Next, the present embodiment will be described in more detail below with reference to the drawings. In addition, all the effects by the following embodiment were confirmed by simulation. In addition, the setting values, measurement values, tables, and the like in the embodiments are examples, and the invention is not limited to this range.

  First, after placing the light irradiation unit on the left of the front of the probe and scanning the probe and the light irradiation unit, the light irradiation unit is arranged on the right of the front of the probe and the probe and light are scanned. An example of scanning the irradiation unit will be described. The configuration of this embodiment will be described with reference to FIG.

  FIG. 1A is a configuration diagram of the first scanning mode, FIG. 1B is a configuration diagram of the second scanning mode, and FIG. 1C is a diagram illustrating scanning lines of the probe.

1 (a) and 1 (b), 1 is a pulse light source, 2 is an optical transmission unit, 3 is a light irradiation unit, 4 is light, 5a is a first holding member, 5b is a second holding member, 6 is a subject, 7 is a light absorber, 8 is a photoacoustic wave, 9 is a probe (corresponding to a receiving unit), and 10 is an outer edge of the reception range of the probe. Further, 11 is a scanning control unit, 12 is an image forming unit (of which 12a is a signal processing unit, 12b is a reconstruction unit), and 13 is a display unit.

  The pulse light source 1 was a titanium / sapphire laser. The used titanium / sapphire laser has a pulse width of 10 nanoseconds, a frequency of 10 Hz, and a wavelength of 797 nm. The light emitted from the pulse light source 1 is transmitted to the light irradiation unit 3 by the light transmission unit 2 including a lens or mirror for processing into a desired shape and a bundle fiber. An optical member is provided in the light irradiation unit 3 so that the light 4 emitted from the light irradiation unit 3 is uniformly irradiated to the subject with a width of 30 mm.

The subject 6 is held between two sheets of the first holding member 5a and the second holding member 5b. Here, the first holding member 5a is a polycarbonate having a thickness of 20 mm, and the second holding member 5b is a polymethylpentene having a thickness of 7 mm. The second holding member 5b is fixed, and the first holding member 5a can be moved in the Z direction. The subject 6 is a phantom that simulates a living body, and has a thickness of 50 mm, a width of 200 mm, a sound velocity of 1500 m / s, a light absorption coefficient of 0.01 mm ⁻¹ , and an equivalent scattering coefficient of 1.1 mm ⁻¹ .

  The light absorber 7 is a cylinder having a radius of 1 mm and a length of 90 mm, and is provided inside the subject 6. The center position is a place 40 mm away from the center of the surface of the second holding member 5b on the subject 6 side in a direction perpendicular to the second holding member 5b.

  For the probe 9, lead zirconate titanate (PZT), which is a piezoelectric material, was used. The element width of the probe 9 is 1 mm, the number of elements is 20 horizontal × 30 vertical, the center frequency of sensitivity is 0.5 MHz, and the full width at half maximum of sensitivity is 1 MHz. In the present embodiment, the outer edge 10 of the probe reception range is defined as a direction having half the sensitivity with respect to the sensitivity in the direction perpendicular to the surface on which the elements of the probe are arranged. It is inclined by 65 degrees with respect to the direction perpendicular to.

  The scanning control unit 11 includes a stage mechanism that drives the light irradiation unit 3 and the probe 9 along the first holding member 5a and the second holding member 5b, and the driving pitch is 1 mm. The scanning range 9 is from the left end to the right end of the subject 6. In this embodiment, the scanning control unit 11 scans the light irradiation unit 3 and the probe 9 back and forth with respect to the subject 6.

  FIG. 1A is a configuration diagram of the forward path, and FIG. 1B is a configuration diagram of the return path. In the forward path, the light irradiation unit 3 and the probe 9 scan while maintaining the first positional relationship in which the center of the light irradiation unit 3 is shifted to the left by 30 mm from the center of the probe 9. This is called the first scanning mode.

  On the other hand, on the return path, the light irradiation unit 3 and the probe 9 scan while maintaining the second positional relationship in which the center of the light irradiation unit 3 is shifted to the right by 30 mm from the center of the probe 9. This is called a second scanning mode. In this case, the region on the subject irradiated with light in the first scanning mode and the region on the subject irradiated with light in the second scanning mode have a partially common region.

  When the imaging range is long in the Y direction, as shown in FIG. 1C, the light irradiation unit 3 and the probe 9 move to the next scanning line, and perform a reciprocating scan again. In the present embodiment, the distance between adjacent scanning lines is 30 mm. This series of operations continues until the entire imaging range is imaged. In FIG. 1C, the forward path and the backward path are shifted from each other, but they are actually on the same line.

The image forming unit 12 forms an image of information inside the subject 6 by back projection using the signal received by the probe 9. The pitch of the formed image is 1 mm. More specifically, the signal processing unit performs digital conversion and amplification processing on the analog electric signal, and the reconstruction unit 12b generates volume data using an image reconstruction technique.
The display unit 13 uses a liquid crystal monitor to display an image in the subject 6 on which an image has been formed.

(Processing flow)
Next, an imaging flow in the present embodiment will be described with reference to FIG.
S101 is a step of starting imaging and is performed by the operator.
Next, in S102, the scanning control unit 11 scans the light irradiation unit 3 and the probe 9 in the first scanning mode. In step S103, the scanning control unit 11 scans the light irradiation unit 3 and the probe 9 in the second scanning mode.

Next, in S104, the scanning control unit 11 determines whether the scanning range is sufficient for the imaging range. If the scanning range is insufficient (S104 = NO), the process proceeds to S105, and the light irradiation unit 3 and the probe 9 move to the next scanning line. Then, the process returns to S102.
If the scanning range is sufficient (S104 = YES), the process proceeds to S106, and the image forming unit 12 generates the characteristic information in the subject 6 based on the signal received by the probe 9.
In step S107, the display unit 13 displays information in the subject 6. Finally, imaging is completed in S108.

The effect of this embodiment by the above apparatus configuration and imaging flow will be described with reference to FIGS.
FIG. 3A shows an image formed at the center in the Y direction of the light absorber 7 when the light irradiation unit 3 and the probe 9 are imaged without shifting in the X direction. The X axis in FIG. 3A is the distance in the X direction from the left end of the holding member 5b, and the Y axis is the Z direction distance from the surface of the holding member 5b on the subject 6 side. FIG. 3B is a profile of image intensity at a depth where the light absorber 7 is located in FIG.

  FIG. 4A is an image formed at the center in the Y direction of the light absorber 7 when the light irradiation unit 3 and the probe 9 are imaged while being shifted by 30 mm in the X direction. FIG. 4B is a cross-sectional view at a depth where the light absorber 7 is located in FIG.

  In FIG. 3B, the full width at half maximum of the light absorber 7 is 3 mm, and in FIG. 4B, the full width at half maximum of the light absorber 7 is 2 mm. From this, it can be seen that the resolution is improved by this embodiment. In the present embodiment, scanning is performed without changing the positions of the light irradiation unit and the probe for each step, so that the imaging time is shortened and the burden on the operator and the subject is reduced. Furthermore, since it can be imaged with one probe, it is inexpensive.

  However, the number of reciprocations and the amount of shift between the light irradiation unit 3 and the probe 9 are not limited to this. Further, the direction in which the light irradiation unit 3 and the probe 9 are shifted is not limited to the X direction, and may be shifted in the Y direction. Further, the light irradiation unit 3 and the probe 9 do not necessarily need to be reciprocated. It is also possible to scan multiple times in one direction.

[Embodiment 2]
The second embodiment is an example in which the resolution is improved by shifting the receivable elements of the light irradiation unit and the probe without shifting the light irradiation unit and the probe. This embodiment is particularly effective when the number of elements of the probe is larger than the number of channels that can be received at one time.

  The configuration of this embodiment will be described with reference to FIG. FIG. 5A is a block diagram of the first scanning mode, FIG. 5B is a block diagram of the second scanning mode, and FIG. 5C is a diagram showing elements that can be received in the first scanning mode. FIG. 5D is a diagram showing elements that can be received in the second scanning mode.

5A to 5D, 1 to 8 and 10 to 13 are the same as those in the first embodiment, and thus the description thereof is omitted. The number of elements of the probe 9a is 40 elements in the X direction and 30 elements in the Y direction, and the number of channels that can be received at one time is 600. Other characteristics are the same as those of the first embodiment.
In the first scanning mode, reception is performed by 20 × 30 elements in the left half of the 40 elements, and in the second scanning mode, reception is performed by 20 × 30 elements in the right half. This switching is performed by the switching unit 14 based on information related to scanning by the scanning control unit 11.

(Processing flow)
Next, an imaging flow in the present embodiment will be described with reference to FIG.
S201 is a step of starting imaging and is performed by the operator.
In step S202, the scanning control unit 11 scans the light irradiation unit 3 and the probe 9a in the first scanning mode.
In step S203, the switching unit 14 switches the probe element used for reception.
In step S204, the scanning control unit 11 scans the light irradiation unit 3 and the probe 9a in the second scanning mode.

In step S205, the scanning control unit 11 determines whether the scanning range is sufficient for the imaging range. If the scanning range is insufficient (S205 = NO), the process proceeds to S206, and the light irradiation unit 3 and the probe 9a move to the next scanning line. Then, the process returns to S202.
If the scanning range is sufficient (S205 = YES), the process proceeds to S207, and the image forming unit 12 forms information in the subject 6 based on the signal received by the probe 9a.
Next, in S208, the display unit 13 displays information in the subject 6. Finally, imaging is completed in S209.

  The result of this embodiment by the above apparatus configuration and imaging flow will be described. The full width at half maximum of the light absorber 7 was 3 mm when imaging was performed using the central 20 × 30 element among the 40 × 30 elements of the probe. On the other hand, the full width at half maximum of the light absorber 7 was 2 mm when the left half 20 × 30 element and the right half 20 × 30 element were switched and imaged. From this, it can be seen that the resolution is improved by this embodiment.

  In the present embodiment, the light irradiation unit 3 and the probe 9a do not need to be shifted, so that there is an advantage that the control of the scanning control unit 11 is easier than the first embodiment. In this embodiment, half of the probe elements are used in the first scanning mode and the remaining half of the elements are used in the second scanning mode. However, the present invention is not limited to this. For example, the element used in the first scanning mode and the element used in the second scanning mode may overlap. There may be an element that is not used in either scanning mode. Further, the probe 9 is not necessarily required to scan. Specifically, it is possible to simply switch the receiving element without scanning the probe 9.

[Embodiment 3]
The third embodiment is an example in which an image forming position to which an operator pays attention is specified, and the scanning control unit determines an amount of shifting the light irradiation unit and the probe based on the specified position. The configuration of the present embodiment will be described with reference to FIGS. FIG. 7A is a block diagram of the first scanning mode, and FIG. 7B is a block diagram of the second scanning mode.

  In FIG. 7, since 1 to 13 are the same as those in the first embodiment, the description thereof is omitted. The first input unit 15 receives an image forming position noted by the operator when it is input. The scanning control unit 11 determines the amount by which the light irradiation unit 3 and the probe 9 are shifted based on the input information and the first table stored in the first storage unit.

FIG. 8 is a first table in this embodiment. The first table describes the relationship between the depth that the operator pays attention to and the amount by which the light irradiation unit 3 and the probe 9 are shifted. This relationship is obtained by performing a simulation in advance to obtain an appropriate value. In the case where the depth is not described, linear interpolation is performed from the amount of shifting the light irradiation unit 3 and the probe 9 at the depths before and after the depth. Note that the values described in the first table are not limited to this, and may be determined according to various conditions and measurement requirements.

(Processing flow)
Next, an imaging flow in the present embodiment will be described with reference to FIG.
In step S <b> 301, the image forming position focused by the operator is input to the first input unit 15.
Next, in S302, the scanning control unit 11 receives the information input to the first input unit 15 and the first table stored in the first storage unit, and based on them, the first positional relationship and A second positional relationship is determined.
Next, in S303, the operator starts imaging.

In step S304, the scanning control unit 11 scans the light irradiation unit 3 and the probe 9 in the first scanning mode. At this time, in the first positional relationship, the center of the light irradiation unit 3 is 30 mm to the left of the center of the probe 9.
In step S305, the scanning control unit 11 scans the light irradiation unit 3 and the probe 9 in the second scanning mode. At this time, in the second positional relationship, the center of the light irradiation unit 3 is located 30 mm to the right of the center of the probe 9.

In step S306, the scanning control unit 11 determines whether the scanning range is sufficient for the imaging range. If the scanning range is insufficient (S306 = NO), the process proceeds to S307, and the light irradiation unit 3 and the probe 9 move to the next scanning line. Then, the process returns to S304.
If the scanning range is sufficient in S306 (S306 = YES), the process proceeds to S308, and the image forming unit 12 forms information in the subject 6 based on the signal received by the probe 9.
In step S309, the display unit 13 displays information in the subject 6. Finally, imaging is completed in S310.

In the present embodiment using the above-described apparatus configuration and imaging flow, there is an advantage that it is possible to perform imaging suitable for the image forming position noted by the operator.
In the above description, the image forming position is described. However, actual image data may not be generated, but characteristic information may be generated. Various methods such as coordinate designation, GUI designation while referring to an image on the display unit, and condition designation can be used as the position designation method. The position designation can also include a depth designation.

[Embodiment 4]
The fourth embodiment is an example in which the operator inputs the first positional relationship and the second positional relationship, and the scanning control unit scans the light irradiation unit and the probe based on the input information. The configuration of this embodiment will be described with reference to FIG. FIG. 10A is a configuration diagram of the first scanning mode, and FIG. 10B is a configuration diagram of the second scanning mode.

  In FIG. 10, since 1 to 13 are the same as those of the first embodiment, the description thereof is omitted. The 2nd input part 17 receives the 1st positional relationship and 2nd positional relationship which an operator inputs. The scanning control unit 11 scans the light irradiation unit 3 and the probe 9 based on the input information.

(Processing flow)
Next, an imaging flow in the present embodiment will be described with reference to FIG.
In S <b> 401, the operator inputs the first positional relationship and the second positional relationship to the second input unit 15. In this embodiment, the shift amount is input as 30 mm.
Next, in S402, the operator starts imaging.

In step S403, the scanning control unit 11 scans the light irradiation unit 3 and the probe 9 in the first scanning mode. At this time, in the first positional relationship, the center of the light irradiation unit 3 is 30 mm to the left of the center of the probe 9.
In step S404, the scanning control unit 11 scans the light irradiation unit 3 and the probe 9 in the second scanning mode. At this time, in the second positional relationship, the center of the light irradiation unit 3 is located 30 mm to the right of the center of the probe 9.

In step S <b> 405, the scanning control unit 11 determines whether the scanning range is sufficient for the imaging range. If the scanning range is insufficient (S405 = NO), the process proceeds to S406, and the light irradiation unit 3 and the probe 9 move to the next scanning line. Then, the process returns to S403.
If the scanning range is sufficient in S405 (S405 = YES), the process proceeds to S407, and the image forming unit 12 forms information in the subject 6 based on the signal received by the probe 9.
In step S <b> 408, the display unit 13 displays information in the subject 6. Finally, the imaging ends in S409.

  In the present embodiment based on the above-described apparatus configuration and imaging flow, the operator can freely determine the first positional relationship and the second positional relationship, so the first positional relationship and the second positional relationship are determined by the subject 6. There is an advantage that it can be determined appropriately according to the characteristics.

[Embodiment 5]
The fifth embodiment is an example in which the measurement unit measures the thickness of the subject, and the scanning control unit determines the first positional relationship and the second positional relationship based on the measured information. The configuration of this embodiment will be described with reference to FIG. FIG. 12A is a configuration diagram of the first scanning mode, and FIG. 12B is a configuration diagram of the second scanning mode.

  In FIG. 12, since 1 to 13 are the same as those in the first embodiment, the description thereof is omitted. The measuring unit 18 measures the distance from the second holding member 5b, that is, the thickness of the subject 6 by measuring the position of the first holding member 5a. The measured information is sent to the scanning control unit 11. The scanning control unit 11 includes a second storage unit 19 that stores a second table for determining the first positional relationship and the second positional relationship based on the measured information. The scanning control unit 11 scans the light irradiation unit 3 and the probe 11 based on the information measured by the measurement unit 18 and the second table.

  FIG. 13 shows a second table in the present embodiment. The second table describes the relationship between the thickness of the subject 6 and the amount by which the light irradiation unit 3 and the probe 9 are displaced. This relationship is obtained by performing a simulation in advance to obtain an appropriate value. For the case where the thickness of the subject is not described, linear interpolation is performed from the amount of shifting the light irradiation unit 3 and the probe 9 at the thickness before and after that. However, the values described in the second table are not limited to this.

(Processing flow)
Next, an imaging flow in the present embodiment will be described with reference to FIG.
In S501, the measurement unit 18 measures the thickness of the subject 6.
In step S <b> 502, the scan control unit 11 determines the first positional relationship and the second positional relationship based on the measured information. In this embodiment, since the thickness of the subject 6 is 50 mm, the shift amount is determined to be 30 mm from FIG.
In step S503, the operator starts imaging.

In step S504, the scanning control unit 11 scans the light irradiation unit 3 and the probe 9 in the first scanning mode. At this time, in the first positional relationship, the center of the light irradiation unit 3 is 30 mm to the left of the center of the probe 9.
In step S505, the scanning control unit 11 scans the light irradiation unit 3 and the probe 9 in the second scanning mode. At this time, in the second positional relationship, the center of the light irradiation unit 3 is located 30 mm to the right of the center of the probe 9.

In step S <b> 506, the scanning control unit 11 determines whether the scanning range is sufficient for the imaging range. If the scanning range is insufficient (S506 = NO), the process proceeds to S507, and the light irradiation unit 3 and the probe 9 move to the next scanning line. Then, the process returns to S504.
If the scanning range is sufficient in S506 (S506 = YES), the process proceeds to S508, and the image forming unit 12 forms an image of information in the subject 6 based on the signal received by the probe 9.
In step S509, the display unit 13 displays information in the subject 6. Finally, imaging is completed in S510.

  The present embodiment using the above-described apparatus configuration and imaging flow has an advantage that the first positional relationship and the second positional relationship can be automatically and appropriately set even if the thickness of the subject changes.

[Embodiment 6]
In the first embodiment, the resolution is improved by shifting the image of the light irradiation unit and the probe. However, as can be seen from a comparison between FIG. 1B and FIG. 2B, the image intensity of the light absorber was reduced to 74%. In the sixth embodiment, whether the signal received by the probe is used for image formation is selectively determined according to the position at which the probe has received the photoacoustic wave, thereby suppressing the reduction in image intensity. In this example, the resolution is improved.

  The configuration of this embodiment will be described with reference to FIG. FIG. 15A is a block diagram of the first scanning mode, and FIG. 15B is a block diagram of the second scanning mode. In FIG. 15, since 1 to 13 are the same as those in the first embodiment, the description thereof is omitted. The third storage unit 20 determines whether to use the signal received by the probe 9 for image formation, based on the position where the probe 9 receives the photoacoustic wave 8 and the position where the image is formed. The third table is stored. The image forming unit 12 forms an image based on the third table.

  FIG. 16 shows a third table in the present embodiment. In the third table, the relationship between the coordinates of the image forming position and the coordinates of the element used for image formation is described for each of the first scanning mode and the second scanning mode. The element coordinates are defined such that the left end of the subject 6 is X = 0 mm and the right direction is a positive direction. Further, the surface of the second holding member 5b on the subject 6 side is defined as Z = 0 mm, the direction perpendicular to the second holding member 5b and toward the first holding member 5a is defined as a positive direction.

The way of viewing the third table will be described. For example, when forming an image of a voxel of (X, Z) = (100, 40) in the first scanning mode, referring to FIG. 16 (a), among the signals acquired by the probe 9 It can be seen that it is sufficient to form an image using only a signal received by an element of X ≧ 100 mm.
In the case of the second scanning mode, referring to the corresponding part in FIG. 16B, image formation is performed using only signals received by the element of X ≦ 100 mm among signals acquired by the probe 9. I understand that I should do it.

This relationship is obtained by performing a simulation in advance to obtain an appropriate value. If the coordinates are not described, linear interpolation is performed from the coordinates of the elements used for image formation at the coordinates before and after the coordinates. However, the values described in the third table are not limited to this. For example, the position of an element used for image formation can be determined for each depth of image formation, and a table can be provided for each characteristic of a probe or a subject. Further, a table can be provided in accordance with the amount by which the light irradiation unit 3 and the probe 9 are shifted.

(Processing flow)
Next, an imaging flow in the present embodiment will be described with reference to FIG.
In S601, the operator starts imaging.
In step S602, the scanning control unit 11 scans the light irradiation unit 3 and the probe 9 in the first scanning mode. At this time, in the first positional relationship, the center of the light irradiation unit 3 is 30 mm to the left of the center of the probe 9.

In step S603, the scanning control unit 11 scans the light irradiation unit 3 and the probe 9 in the second scanning mode. At this time, in the second positional relationship, the center of the light irradiation unit 3 is located 30 mm to the right of the center of the probe 9.
In step S604, the scanning control unit 11 determines whether the scanning range is sufficient for the imaging range. If the scanning range is insufficient (S604 = NO), the process proceeds to S605, and the light irradiation unit 3 and the probe 9 move to the next scanning line. Then, the process returns to S602.

If the scanning range is sufficient in S604 (S604 = YES), the process proceeds to S606, and the image forming unit 12 forms an image of information in the subject 6 based on the signal received by the probe 9.
In step S <b> 607, the display unit 13 displays information in the subject 6. Finally, imaging is terminated in S608.

  The effects of the present embodiment based on the above apparatus configuration and imaging flow will be described with reference to FIGS. 3, 4, and 18. FIG. 18A is an image at the center in the Y direction of the light absorber 7 when an image is formed based on the third table. FIG. 18B is a cross-sectional view at a depth where the light absorber 7 is located in FIG.

  In FIG.18 (b), the full width at half maximum of the light absorber 7 is 2 mm, and is the same as that of FIG.4 (b). On the other hand, when FIG. 18B is compared with FIG. 3B, the image intensity of the light absorber is increased to 205% by selecting an element used for image formation. This means that the image intensity is improved by 2.8 times compared to the 74% reduction in the first embodiment. At this time, since the number of elements used for image formation is half that of the first embodiment, the noise intensity is doubled. Therefore, in this embodiment, the S / N is improved twice as compared with the first embodiment.

  Thus, the image intensity can be reduced by selectively determining whether the signal received by the probe according to the present embodiment is used for image formation according to the position where the probe has received the photoacoustic wave. It can be seen that the resolution can be improved while suppressing.

  In the drawings for explaining the respective embodiments, the light irradiation unit 3 and the probe 9 have a face-to-face positional relationship that is disposed on the side facing the subject 6. However, as already described, the positional relationship between the two is not limited to this. For example, the light irradiation unit may be disposed on the same side as the probe, and the subject may be irradiated with light from behind or from the side of the probe. Further, the subject may be irradiated from both sides. Also in these positional relationships, the resolution at the time of imaging can be improved by changing the mode for each of a plurality of scans as in the present invention.

  If the scanning control is possible, a configuration in which the holding member 5 is not provided can be employed. Alternatively, a shape other than a plane, for example, a curved shape suitable for the breast or a cup-shaped holding member can be used. Alternatively, a non-plate member such as a flexible member or a film member can be used.

1: pulse light source, 2: light transmission unit, 3: light irradiation unit, 9: probe, 11: scanning control unit, 12
: Image forming unit

Claims (12)

An irradiation unit for irradiating the subject with light; and
A scanning control unit for moving the irradiation unit on the subject a plurality of times;
A receiving unit that receives an acoustic wave generated from the subject by irradiation of light from the irradiation unit and converts the acoustic wave into an electrical signal;
A processing unit that generates characteristic information inside the subject using the electrical signal output by the receiving unit;
Have
The scanning control unit is configured to move the irradiation unit such that a region on the subject irradiated with light in each of the plurality of movements has at least a partially common region;
The processing unit generates the characteristic information using an electrical signal output by the receiving unit for each of the plurality of movements in which the positional relationship between the irradiation unit and the receiving unit is different. Sample information acquisition device. In the scanning control unit, the first scanning mode in which the irradiation unit and the receiving unit move while maintaining the first positional relationship, and the irradiation unit and the receiving unit are the first positional relationship. The subject information acquiring apparatus according to claim 1, wherein the control includes a second scanning mode that moves while maintaining a different second positional relationship. The irradiation unit and the receiving unit are arranged to face each other with the subject interposed therebetween, and the first positional relationship is a positional relationship in which the center of the irradiation unit and the center of the receiving unit are shifted. The second positional relationship is a positional relationship in which a center of the irradiation unit and a center of the receiving unit are shifted, and a positional relationship different from the first positional relationship. Subject information acquisition apparatus. The center of the said irradiation part in said 1st positional relationship and the center of the said irradiation part in said 2nd positional relationship are located oppositely via the center of the said receiving part. Subject information acquisition apparatus. The scanning control unit controls an amount of shifting the irradiation unit and the reception unit using the first positional relationship and the second positional relationship input by an operator. Or the object information acquiring apparatus according to 4; An input unit for receiving an input of a position for generating the characteristic information in the subject;
6. The object information acquisition according to claim 3, wherein the scanning control unit controls an amount of shifting the irradiation unit and the receiving unit based on information on an input position. apparatus. The object information acquisition according to any one of claims 3 to 6, wherein the scanning control unit controls an amount of shifting the irradiation unit and the receiving unit based on a thickness of the subject. apparatus. The processing unit determines whether to use the acoustic wave received by the receiving unit for generating the characteristic information based on a position of the receiving unit and a position where the characteristic information is generated. Item 8. The subject information acquisition apparatus according to any one of Items 1 to 7. An irradiation unit for irradiating the subject with light; and
A scanning control unit for moving the irradiation unit on the subject a plurality of times;
A receiving unit including a plurality of elements that receive an acoustic wave generated from the subject by irradiation of light from the irradiation unit and convert it into an electrical signal;
A processing unit that generates characteristic information inside the subject using the electrical signal output by the receiving unit;
Have
The receiving unit selects a receiving element group to be used for reception from the plurality of elements so that the elements that receive the acoustic wave in each of the plurality of movements are at least partially different.
The processing unit generates the characteristic information using an electrical signal output by the receiving unit for each of the plurality of movements in which the positional relationship between the irradiation unit and the receiving element group of the receiving unit is different. A subject information acquisition apparatus characterized by the above. The control performed by the scanning control unit includes movement of the irradiation unit and the receiving unit according to a first scanning mode and movement according to a second scanning mode. Sample information acquisition device. The irradiation unit and the receiving unit are arranged to face each other with the subject interposed therebetween, and the receiving element group in the second scanning mode is not selected as the receiving element group in the first scanning mode. The object information acquiring apparatus according to claim 10, comprising at least a part of the element. The receiving element group in the first scanning mode and the receiving element group in the second scanning mode are located opposite to each other via the center of the receiving unit. Sample information acquisition device.

Images