JP2017046762A - Subject information acquisition device and method for driving subject information acquisition device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce acquisition of input signals that does not significantly contribute to acquiring subject information in a high resolution manner.SOLUTION: The subject information acquisition device includes: a holding member with an opening into which a subject part that is part of a subject is inserted; and an opening regulation member for regulating a shape of the opening. A movement area of a support body for supporting a transducer is defined based on the shape of the opening.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a subject information acquisition apparatus and a method for driving a subject information driving apparatus.

  Research on optical imaging devices that irradiate a subject such as a living body from a light source such as a laser and image information in the subject obtained based on the light incident on the subject is actively progressing in the medical field. It has been. As one of the optical imaging techniques, there is Photoacoustic Imaging (PAI: photoacoustic imaging). In photoacoustic imaging, a subject is irradiated with pulsed light generated from a light source, and acoustic waves generated from the subject tissue that absorbs the energy of pulsed light that has propagated and diffused within the subject are received. Based on the received signal The subject information is imaged.

  In photoacoustic imaging, a difference in absorption rate of light energy between a target site such as a tumor and other tissues is used. The test site absorbs the irradiated light energy and expands instantaneously. Elastic waves (hereinafter also referred to as photoacoustic waves) generated at that time are received by the probe. By mathematically analyzing the received signal, information in the subject, in particular, an initial sound pressure distribution, a light energy absorption density distribution, or a light absorption coefficient distribution of the generated photoacoustic wave can be obtained. Such information can also be used for quantitative measurement of a specific substance in the subject, for example, oxygen saturation in blood. In recent years, preclinical research for imaging a blood vessel image of a small animal using this photoacoustic imaging and clinical research for applying this principle to diagnosis of breast cancer or the like have been actively promoted (Non-patent Document 1).

  Patent Document 1 describes a photoacoustic apparatus that performs photoacoustic imaging using a probe in which a transducer is arranged on a hemisphere. According to this probe, it is possible to receive photoacoustic waves generated in a specific region, specifically, near the center of the hemisphere with high sensitivity. For this reason, the resolution of the subject information in the specific region is increased. In Patent Document 1, this probe is scanned in a certain plane, and then the probe is moved in a direction perpendicular to the scanning plane and scanned in another plane. It is described that it is performed once. According to the scanning described in Patent Document 1, it is described that subject information with high resolution can be acquired in a wide range.

JP 2012-179348 A

“Photoacoustic angiography of the breast”, Medical Physics, Vol. 37, no. 11, November 2010

  However, in the scan described in Patent Document 1, a photoacoustic wave may be received even when a region with high sensitivity is not in a region of interest for which subject information is desired to be acquired. The reception signal acquired at this time is a reception signal that does not greatly contribute to acquiring subject information in the region of interest with high resolution. That is, in the scan described in Patent Document 1, the efficiency of acquiring a reception signal for acquiring subject information with high resolution in a region of interest may be low.

  Therefore, an object of the present invention is to provide a photoacoustic apparatus that can efficiently acquire a reception signal for increasing the resolution of subject information in a region of interest.

  A subject information acquisition apparatus according to one aspect of the present invention includes a light source, a plurality of transducers that receive an acoustic wave generated by irradiating the subject with light generated from the light source, and output an electrical signal; A support body that supports the plurality of transducers and a holding member that holds the subject so that the directional axes of the plurality of transducers are gathered to insert a test portion that is a part of the subject. A holding member having a plurality of openings, a moving part that relatively moves the test part and the support, a moving area setting part that sets a moving area of the moving part, and an opening that defines the shape of the opening And the moving area setting section determines the moving area based on information related to the opening.

  According to the present invention, it is possible to efficiently acquire a received signal for increasing the resolution of subject information in a region of interest.

It is the schematic which shows the structure of the subject information acquisition apparatus which concerns on 1st Embodiment. It is a flowchart which shows operation | movement of the subject information acquisition apparatus which concerns on 1st Embodiment. It is the schematic which shows the connection of the subject information acquisition apparatus which concerns on 1st Embodiment. It is the schematic which shows the movement area | region of the support body with respect to a 1st aperture | diaphragm | squeeze part. It is the schematic which shows the movement area | region of the support body with respect to a 2nd aperture | diaphragm | squeeze part. It is the schematic which shows the structure of the subject information acquisition apparatus which concerns on 2nd Embodiment. It is the schematic which shows the structure of the aperture_diaphragm | restriction part which concerns on 2nd Embodiment. It is a flowchart which shows operation | movement of the subject information acquisition apparatus which concerns on 2nd Embodiment.

  A preferred embodiment of the present invention will be described with reference to the drawings.

(First embodiment)
First, the subject information acquiring apparatus according to the first embodiment of the present invention will be described. FIG. 1 is a schematic diagram illustrating a configuration of a subject information acquisition apparatus 100 according to the first embodiment.

  The test part E is a measurement target. Specific examples include parts of a living body such as a breast, a hand, and a foot. When calibrating or adjusting the apparatus, a phantom that simulates the acoustic characteristics and optical characteristics of a living body serves as the test part E. Here, the acoustic characteristics are propagation speed and attenuation rate of acoustic waves, and the optical characteristics are light absorption coefficient and scattering coefficient. In order to perform photoacoustic wave measurement (hereinafter also referred to as photoacoustic measurement), a light absorber having a large light absorption coefficient of light emitted from the light source 117 described later needs to be present in the test portion E. There is. When the test part E is a living body, hemoglobin, water, melanin, collagen, lipid, and the like are applicable. When the test part E is a phantom, a substance simulating optical characteristics is enclosed in the phantom as a light absorber.

  The light source 117 is a device that generates pulsed light. As the light source, a laser capable of obtaining a large output is desirable, but a light emitting diode or a flash lamp may be used. In order to generate photoacoustic waves effectively, light must be irradiated in a sufficiently short time according to the thermal characteristics of the subject. When the subject is a living body, the pulse width of the pulsed light generated from the light source 117 is preferably set to several tens of nanoseconds or less. The wavelength of the pulsed light is in the near infrared region called a biological window, and is preferably about 700 nm to 1200 nm. The light in this region can reach a relatively deep part of the living body, and information on the deep part of the living body can be obtained. If measurement is performed only near the surface of a living body, pulsed light in the visible to near infrared region of about 500 to 700 nm may be used. In particular, the wavelength of the pulsed light is desirably a region where the observation target has a high absorption coefficient.

  The holding unit 106 is attached to the opening of the support base 102 that supports the subject, holds the subject E that is part of the subject inserted from the opening, and maintains the shape of the subject E. It is a holding member. A plurality of holding portions 106 having different shapes may be prepared and replaced. In this case, it is preferable to include an attachment portion for detachably attaching the object information acquisition apparatus wave and holding portion 106. A different shape of the holding unit 106 may be selected by the user in accordance with the type and size of the test portion E. If the material of the holding part 106 is a material close to the acoustic impedance of the test part E, it is possible to reduce reflection of acoustic waves at the interface between the test part E and the holding part 106. The thickness of the holding unit 106 is preferably thin in order to reduce reflection of acoustic waves by the holding unit 106. When the test part E is irradiated with light via the holding unit 106 as in the present embodiment, or when an appearance image of the test part E is acquired by an imaging device described later, the holding unit 106 transmits light. Is preferably high. For example, polymethylpentene, polyethylene terephthalate, polycarbonate and the like are suitable. When the test part E is a breast, the shape of the holding part 106 is preferably a shape obtained by cutting a sphere in a certain cross section in order to reduce deformation of the breast shape and keep the shape constant. The holding unit 106 that holds the breast is not limited to the cup-shaped holding unit using the above-described material, but may be a sheet-like film, a rubber sheet, or the like that is deformed by contact with the test part E. May be. Further, the measurement may be performed without using the holding unit 106.

  The optical system 114 transmits the pulsed light generated by the light source 117. Specifically, it is an optical device such as a lens, a mirror, a prism, an optical fiber, and a diffusion plate. Moreover, when guiding light, the shape and light density may be changed using these optical devices so as to obtain a desired light distribution. The optical apparatus is not limited to those described here, and any optical apparatus may be used as long as it satisfies the above functions. Further, the maximum permissible exposure (MPE: Maximum Permissible Exposure) is determined by the safety standard shown below for the intensity of light allowed to irradiate the living tissue. (IEC 60825-1: Safety of laser products, JIS C 6802: Safety standards for laser products, FDA: 21 CFR Part 1040.10, ANSI Z136.1: Laser Safety Standards, etc.). The maximum allowable exposure value defines the intensity of light that can be irradiated per unit area. For this reason, it is preferable to spread the light to a certain area as shown by the broken line in FIG.

  The transducer 109 detects an acoustic wave generated when the light emitted from the light source 117 is irradiated from the optical system 114 onto the test part E, and outputs an electrical signal. It is desirable that the photoacoustic wave from the test portion E has high reception sensitivity and a wide frequency band with sensitivity. As a member constituting the transducer 109, a piezoelectric element using a piezoelectric ceramic material typified by PZT (lead zirconate titanate) or a polymer piezoelectric film material typified by PVDF (polyvinylidene fluoride) is used. Can do. In addition to the piezoelectric element, for example, a capacitive element such as cMUT (Capacitive Micro-machined Ultrasonic Transducers), a transducer using a Fabry-Perot interferometer, or the like can be used. However, the present invention is not limited to those described here, and any other one may be used as long as the above functions are satisfied.

  The support body 107 according to this embodiment is a substantially hemispherical container having a shape obtained by cutting a true sphere with a plane passing through a substantially center. A plurality of transducers 109 are provided inside the hemispherical support 107, and an optical system 114 is provided at the bottom of the hemisphere. The support 107 also functions as a container for holding an acoustic matching material 105 described later, and the acoustic matching material 105 is filled inside the support 107. In order to support these members, the support body 107 is preferably configured using a metal material having high mechanical strength. The receiving surface of each of the plurality of transducers 109 provided on the support 107 is arranged so that the direction with the highest sensitivity of the receiving directivity is directed toward a specific region. Specifically, the plurality of transducers 109 are arranged in a predetermined region of interest of the test part E so that the directional axes of the transducers 109 are gathered in a specific region. In this embodiment, it arrange | positions so that a directional axis may cross | intersect in a specific location (for example, the curvature center of a support body). By collecting the directional axes of the plurality of transducers 109 in a specific area, it is possible to receive acoustic waves generated from the specific area with higher sensitivity than when the directional axes are arranged in parallel. As a result, the resolution of the image in the specific region can be increased. In the present embodiment, this specific region is referred to as a “high sensitivity region”, and the “high sensitivity region” refers to a region from the point with the highest resolution to the half of the highest resolution. Note that the arrangement of the plurality of transducers 109 may be any arrangement as long as a desired high sensitivity region can be formed. It should be noted that the directional axes of all the transducers 109 do not necessarily intersect at one point as long as a high-sensitivity region in which the directional axes of a plurality of transducers 109 are gathered, and the directional axes of any two transducers 109 do not intersect. Also good. In other words, at least a part of the elements of the plurality of transducers 109 may be arranged on the support 107 so that the photoacoustic wave generated in the high sensitivity region can be received with high sensitivity. The shape of the support 107 is not limited to a hemispherical shape, and may be any shape as long as the plurality of transducers 109 can be arranged as described above. The support 107 may have a curved surface other than the surface on a true sphere. In addition, it is preferable to arrange the plurality of transducers 109 on the support 107 so that the high sensitivity region determined by the arrangement of the plurality of transducers 109 is formed at a position where the test portion E is assumed to be located. When there is a holding unit 106 that holds the shape of the test part E as in this embodiment, a plurality of transducers 109 are arranged on the support 107 so that a high-sensitivity region is formed in the vicinity of the holding unit 106. Also good. Further, as in the present embodiment, when there is a diaphragm 101 that defines the shape of the test part E, a plurality of transducers 109 are arranged on the support 107 so that a high sensitivity region is formed in the vicinity of the diaphragm 101. May be.

  The scanning stage 108 as a moving unit moves the relative position of the support 107 with respect to the test portion E in the X, Y, and Z directions in FIG. The scanning stage 108 includes a guide mechanism (not shown) in the X, Y, and Z directions, a drive mechanism in the X, Y, and Z directions, and a position sensor that detects the positions of the support in the X, Y, and Z directions. . As shown in FIG. 1, since the support 107 is mounted on the scanning stage 108, it is preferable to use a linear guide or the like that can withstand a large load as the guide mechanism. Moreover, as a drive mechanism, a lead screw mechanism, a link mechanism, a gear mechanism, a hydraulic mechanism, etc. can be used. As the driving force, a motor or the like can be used. As the position sensor, an optical or magnetic encoder can be used. However, the configuration is not limited to the above-described configuration, and any configuration may be used as long as the relative position between the test portion E and the support 107 can be changed. In this embodiment, the case where the support 107 is moved in a state where the position of the test part E is fixed is shown, but the moving part is configured to move at least one of the support 107 and the test part E. I just need it.

  The electric signal acquisition unit 115 collects electric signals from a plurality of transducers 109 in time series, and typically, from an element such as a CPU, an OP amplifier, an A / D converter, or a circuit such as an FPGA or an ASIC. Composed. The analog signals received from the plurality of transducers 109 are filtered, amplified, and A / D converted, and transferred to the processing operation unit 110 described later. The electrical signal acquisition unit 115 may be configured not only with one element or circuit but also with a plurality of elements or circuits.

  The processing calculation unit 110 includes a calculation unit 111 and a storage unit 112. The arithmetic unit 111 is typically composed of elements such as a CPU, GPU, A / D converter, and circuits such as an FPGA and an ASIC. The calculation unit 111 performs signal processing on the electrical signal output from the electrical signal acquisition unit 115 and acquires information inside the test unit E. In addition, as illustrated in FIG. 3, the calculation unit 111 as a control unit can control the operation of each component configuring the subject information acquisition apparatus via the bus 120. The storage unit 112 typically includes a storage medium such as a ROM, a RAM, and a hard disk. Note that the storage unit 112 may be configured not only from one storage medium but also from a plurality of storage media. The storage unit 112 can also store a program to be executed by the calculation unit 111. However, the program is stored in the nonvolatile storage medium of the storage unit 112. Moreover, it is preferable that the processing calculation unit 110 is configured to be able to pipeline process a plurality of signals at the same time. As a result, it is possible to shorten the time until the object information is acquired.

  The display unit 118 displays information on the test part E output from the processing calculation unit 110 as a distribution image, numerical data, or the like. A liquid crystal display is typically used, but other types of displays such as a plasma display, an organic EL display, and an FED may be used. The display unit 118 may be provided separately from the subject information acquisition apparatus.

  The input unit 119 is configured so that the user can input desired information to the processing calculation unit 110. As the input unit 119, a keyboard, a mouse, a dial, a push button, a touch panel, or the like can be used. When a touch panel is adopted as the input unit 119, the display unit 118 may also serve as the input unit 119. The desired information may include information such as the attention area designation and the type of the holding unit 106. The input unit 119 may be provided separately from the subject information acquisition apparatus of the present invention.

  The acoustic matching material 105 fills the space between the test part E and the holding part 106 and between the holding part 106 and the transducer 109 and acoustically couples the test part E and the transducer 109. An acoustic matching material 105 made of a different material may be disposed between the test portion E and the holding portion 106 and between the holding portion 106 and the transducer 109. As the acoustic matching material 105, it is necessary to select a material that is close to the acoustic impedance of the test portion E and the transducer 109 and that has a small acoustic wave attenuation. Further, a material that transmits pulsed light generated by the light source 117 is preferable. For example, water, castor oil, gel and the like can be used. Note that the acoustic matching material 105 may be provided separately from the subject information acquisition apparatus.

  The aperture 101 as the opening defining portion is a member that is disposed around the opening of the support base 102 and defines the position of the test portion E in the holding unit 106 and the shape of the opening. Further, it is a member that closes at least a part of the gap between the test portion E and the opening, and reduces leakage of light emitted from the optical system 114 toward the subject. By providing the diaphragm unit 101, it is possible to reduce the irradiation of light to a portion that is not the test part E of the subject. The throttle unit 101 is preferably one that can be adapted to various test parts E, such as the size and shape of the test part E. Therefore, it is preferable to prepare a plurality of aperture portions 101 having different aperture shapes. The shape of the opening may be any shape, such as a circle, an ellipse, a polygon, or a teardrop shape, as long as it can block at least a part of the gap between the test portion and the opening. In the present specification, similar openings having different opening sizes are also referred to as having different opening shapes. That is, the shape information of the opening is information including the size of the opening. The aperture portion 101 is attached to an attachment portion 103 provided on the support base 102. As a method for fixing to the attachment portion 103, any method may be used as long as the position of the throttle portion 101 can be fixed at the time of measurement, such as screwing, fitting, and adhesion.

  The detection unit 104 detects the type of the diaphragm unit 101 attached to the attachment unit 103. The detection unit 104 can employ, for example, a reader that reads information from an ID chip, a barcode, or the like that indicates the type of the diaphragm unit 101 mounted on the diaphragm unit 101. However, the present invention is not limited to this, and any type may be used as long as the type of the aperture 101 can be detected. Further, the information read from the diaphragm unit 101 may not be information directly indicating the shape of the diaphragm unit. For example, information such as unique numbers and symbols assigned to different types of apertures 101 may be recorded on an ID chip, a barcode, or the like. In this case, the subject information acquisition apparatus refers to, for example, data stored in advance in the storage unit 112 that associates a unique number or symbol assigned to the diaphragm unit 101 with the shape of the diaphragm unit 101. The aperture shape of the diaphragm 101 attached to the attachment 103 can be recognized. Furthermore, even if the detection unit 104 is not used, when the user inputs information related to the diaphragm unit 101 installed in the attachment unit 103 by the input unit 119, the subject information acquisition apparatus recognizes the opening shape of the diaphragm unit 101. You may let them.

  The subject information acquisition apparatus 100 may include an imaging unit 113. The imaging unit 113 captures the appearance of the test unit E and the diaphragm unit 101 and outputs a signal to the processing calculation unit 110. The processing calculation unit 110 analyzes the signal output from the imaging unit 113 and generates image data. An optical imaging element such as a CCD sensor or a CMOS sensor can be used for the imaging unit 113. The imaging unit 113 can employ a transducer that transmits and receives acoustic waves, such as a piezo element or a CMUT. Note that some elements of the plurality of transducers 109 may be used as the imaging unit 113. When a transducer capable of transmitting and receiving acoustic waves is used as the imaging unit 113, the shape information of the opening can be acquired by transmitting the acoustic wave to the test part E and receiving the reflected wave from the test part E. . In addition, any element may be employed for the imaging unit 113 as long as an image of the test part E can be generated based on the signal output from the imaging unit 113. Note that the imaging unit 113 and the processing calculation unit 110 serving as an image generation unit may be provided separately from the subject information acquisition apparatus. Further, the imaging unit 113 may be installed anywhere as long as it can shoot the test part E and the diaphragm unit 101.

  A stage control unit 116 serving as a movement region setting unit controls the movement region S, the movement path, and driving of the scanning stage 108 based on information related to the aperture of the diaphragm unit 101. Since an appropriate moving area S for obtaining information in the test portion E differs depending on the aperture shape of the aperture section 101, an appropriate scanning range is set according to the aperture shape of the aperture section 101. Note that the processing operation unit 110 may control the scanning stage 108 without providing the stage control unit 116. When the subject information acquisition apparatus 100 includes the detection unit 104, the stage control unit 116 corresponds to the detection result of the detection unit 104 from the information related to the opening stored in the storage unit 112 in advance. Read information. Then, the moving area S can be set based on the read information.

  Next, FIG. 2 for explaining the operation according to the present embodiment is a diagram showing a flowchart of the operation according to the present embodiment.

  In step S <b> 100, the detection unit 104 detects the type of the diaphragm unit 101 attached to the attachment unit 103, and outputs information on the type of the diaphragm unit 101 to the processing calculation unit 110. Alternatively, the processing calculation unit 110 may generate image data based on the signal output from the imaging unit 113 and detect the type of the aperture unit 101 from the image. For example, the detection is performed by recognizing the barcode, ID, or shape of the diaphragm 101 described in the diaphragm 101. Alternatively, the user uses the input unit 119 to input the type of the diaphragm unit 101 installed in the subject information acquisition apparatus, and outputs information on the type of the diaphragm unit 101 to the processing calculation unit 110. As described above, the information input from the detection unit 104 or the input unit 119 here does not have to be information directly indicating the shape of the opening.

  In step S101, the moving area S of the scanning stage 108 is set. The storage unit 112 of the processing calculation unit 110 stores information related to the apertures of the plurality of diaphragm units 101 in advance. The processing calculation unit 110 reads information on the diaphragm unit 101 of the type detected in step S100 or input by the user from the storage unit 112, and the calculation unit 111 moves the scanning stage 108 based on the read information related to the opening. Region S is calculated. Based on the calculated movement area S, the stage controller 116 is set. At this time, a movement path, a scanning speed, an acceleration profile, and the like may be set. Further, the processing calculation unit 110 may appropriately set the acoustic wave signal acquisition position in the set moving region S. Further, the user may set the signal acquisition position and interval of the acoustic wave in the moving area S using the input unit 119. The position and size of the high sensitivity region G are determined by the arrangement of the plurality of transducers 109. Therefore, the calculation unit 111 forms the high sensitivity region G inside the opening of the diaphragm 101 based on the shape information of the opening of the diaphragm 101 and the arrangement information of the plurality of transducers 109 on the support 107. The movement area S is set as follows. When a plurality of holding units 106 having different sizes can be exchanged, the moving region S is determined based on the size information of the holding unit 106, the information related to the opening defined by the diaphragm unit 101, and the arrangement information of the transducer 109. To do. The storage unit 112 may store in advance information on the high sensitivity region, the holding unit 106, the moving region S corresponding to the diaphragm unit 101, and the acoustic wave signal acquisition position.

  4 (a) and 5 (a) show the mounting portion 103, the diaphragm portion 101 having a different opening shape between the two drawings, and the scanning range in which the high sensitivity region G moves from the positive direction of the Z axis. FIG. FIG. 4A is a diagram illustrating a case where the first aperture portion 101a having a circular opening shape is used. FIG. 5A is a diagram illustrating a case where the second diaphragm portion 101b having a teardrop shape is used. As shown in FIG. 4A, the opening of the first diaphragm portion 101a is larger than the opening of the second diaphragm portion 101b. For this reason, even when the second diaphragm 101b is used, if a moving area S that scans the entire area of the opening of the first diaphragm 101a is set, an area without the test part E (an area outside the opening) ) Is also scanned. As a result, the measurement time becomes longer than necessary, and further, a signal unnecessary for acquiring the information inside the test part E and the subject information in the test part E are not greatly contributed to acquiring with high resolution. Such a signal is also received. On the other hand, when a signal is acquired using the first diaphragm unit 101a, if a moving region that scans the entire moving region S of the second diaphragm unit 101b is set, Information can only be obtained from the department. Therefore, by controlling the moving region S in accordance with the shape of the diaphragm 101, it is possible to prevent the high-sensitivity region G from deviating from the range to be measured (that is, the region of interest) and efficiently acquire information on the range to be measured. be able to. 4 (a) and 5 (a), it is moved by linear motion and direction change. However, the present invention is not limited to this, and if it can move to all signal acquisition positions in the set movement region S, such as spiral motion and spiral motion. Any route is acceptable. When the support 107 is configured to hold the acoustic matching material 105 as in the present embodiment, the surface of the acoustic matching material 105 is disturbed by moving the support 107 without causing a rapid speed change or direction change. Can be suppressed. Further, it is preferable that the driving of the light source 117 and the scanning stage 108 is controlled so that the high sensitivity region G overlaps regardless of which diaphragm unit 101a or 101b is used. In the present embodiment, since the high sensitivity region G has a spherical shape, it is preferable that a signal is acquired at least once before the support 107 moves by a distance equal to the radius of the high sensitivity region G. The smaller the distance that the support 107 is moved during the time from the first pulse light irradiation to the next second pulse light irradiation, the more uniform the resolution. However, if the moving distance is small (that is, the moving speed is slow), it takes time to acquire all signals. Therefore, the interval between the moving speed and the reception signal acquisition time is preferably set as appropriate in consideration of the desired resolution and measurement time. The desired resolution may be set by the user through the input unit 119 or may be a resolution set in advance.

  In FIG. 4B and FIG. 5B, the center O of the high sensitivity region G at each measurement position is indicated by a cross (+). It is preferable to set the moving region S of the support 107 so that the photoacoustic measurement is performed when the center O is formed inside the openings of the aperture portions 101a and 101b. That is, it is preferable to set the moving region S so as to receive an acoustic wave when the center of curvature of the hemispherical support 107 at each measurement position exists inside the opening of the diaphragm 101. Furthermore, as shown in FIGS. 4B and 5B, the signal is also detected when the center O of the high sensitivity region G corresponding to the outermost periphery of the moving region S coincides with the outer edge of the aperture of the aperture. It is more preferable to set the movement area S so as to receive Here, two types of apertures having different aperture shapes are illustrated, but the present invention is not limited to this. The above can be applied if there are two or more diaphragm portions 101 having at least one of the shape of the opening and the size of the opening.

  In step S102, it is confirmed that the test part E has been inserted into the holding unit 106, and measurement is started. The user can visually confirm that the test part E has been inserted into the holding unit 106, and the subject information apparatus includes means for detecting the insertion state of the test part E, and is automatically detected. You may do it.

  In step S103, the support 107 is moved to the measurement position in the movement area S set in step S101. At this time, when the scanning stage 108 sequentially transmits the coordinate information of the support 107 to the processing calculation unit 110, the processing calculation unit 110 can grasp the position of the support 107.

  In step S <b> 104, the light source 117 emits pulsed light, and an acoustic wave is excited by the light absorber in the test portion E by the irradiated pulsed light. The generated acoustic wave propagates in the acoustic matching material 105 and is received by the plurality of transducers 109. The acoustic waves received by the plurality of transducers 109 are converted into electrical signals and sent to the electrical signal acquisition unit 115. The plurality of electrical signals acquired by the electrical signal acquisition unit 115 is sent to the processing calculation unit 110 and stored as electrical signals at the coordinate position of the support in step S103.

  In step S105, it is determined whether electric signals have been acquired at all measurement positions in the movement area S set in step S101. If the electrical signals have not been acquired at all the measurement positions (when the determination in step S105 is NO), the process returns to step S103, and the second measurement different from the first measurement position in the moving region S. The support 107 is moved to the position, and signal acquisition at the second measurement position is performed (step S104). Hereinafter, the same process is repeated until electric signals at all measurement positions in the moving region S set in step S101 are acquired.

  If the reception of photoacoustic waves at all measurement positions in the moving region S set in step S101 is completed (when the determination in step S105 is YES), the process proceeds to step S106. In step S106, the measurement ends. After the measurement is completed, the stage control unit 116 may move the support 107 to the initial position, or may stop the movement at the last measurement position.

  In step S107, the information inside the test part E is acquired by performing processing based on the image reconstruction algorithm on the reception signals acquired in steps S102 to S106. An example of an image reconstruction algorithm for acquiring subject information includes back projection in the time domain or Fourier domain used in tomography technology. Also, an image reconstruction method such as an inverse problem analysis method using an iterative process can be used.

  In step S108, the information inside the part E to be examined acquired in step S107 is displayed on the display unit 118.

  As described above, in the present embodiment, the high-sensitivity region G formed by gathering the directional axes of the plurality of transducers 109 based on the shape information of the aperture of the diaphragm 101 is the interior of the test part E. The moving area S of the scanning stage 108 is determined as shown in FIG. As a result, information in a range to be measured can be efficiently acquired with high image quality, and measurement can be performed in a scanning time suitable for the aperture shape of the diaphragm 101.

(Second Embodiment)
A subject information acquiring apparatus according to the second embodiment will be described. A description of portions common to the first embodiment is omitted. FIG. 6 is a schematic diagram showing the configuration of the subject information acquiring apparatus 200 according to the second embodiment. In the second embodiment, an example is shown in which a plurality of aperture portions are not prepared as in the first embodiment, but an aperture portion having a variable opening shape is applied.

  FIG. 7 is a diagram illustrating a configuration of the diaphragm unit 201 according to the second embodiment. The diaphragm unit 201 according to the second embodiment deforms the opening shape by driving a plurality (here, eight) of wings 202. The wing 202 rotates around the support post 206, and a shaft 207 provided in the drive ring 203 is fitted in the elongated hole 208 provided in the wing 202. The diaphragm unit 201 includes a drive mechanism 204 and a position sensor 205. As the driving mechanism 204, a gear mechanism or the like can be used. As the driving force, a motor or the like can be used. As the position sensor 205, an optical or magnetic encoder or the like can be used. The gear portion 209 of the drive ring 203 and the gear of the drive mechanism 204 are engaged with each other, and the motor of the drive mechanism 204 is driven to rotate about the center X of the aperture portion 201. By rotating the drive ring 203, the wing 202 rotates around the support column 206, and the shape of the opening is deformed. The position sensor 205 detects the amount of rotation of the drive ring 203 and outputs a signal to the processing calculation unit 110. The diaphragm unit 201 is connected to the processing calculation unit 110, and the processing calculation unit 110 controls the driving amount of the motor. The diaphragm 201 is preferably configured to automatically open when the motor is de-energized. The diaphragm unit 201 may have any configuration as long as the opening can be deformed. For example, elastic rubber, sponge, or cloth may be used. Further, the position sensor 205 may be provided in the drive mechanism 204 to detect the number of rotations of the motor.

  FIG. 8 is a diagram showing a flowchart of the operation in the second embodiment. Since only the steps S200 to S202 are different from the flowchart according to the first embodiment, only steps S200 to S202 will be described here.

  In step S <b> 200, the distance between the test part E and the opening end of the diaphragm unit 201 is measured based on the detection result by the distance detection unit. For example, the imaging unit 113 can be used as a distance detection unit that detects the distance between the test unit and the diaphragm unit 201. Based on the signal output from the imaging unit 113, the processing calculation unit 110 generates image data. Subsequently, the processing calculation unit 110 calculates the distance between the test portion E and the opening end of the aperture unit 201 based on the generated image data. For example, based on image data captured from a plurality of directions by the imaging unit 113, the processing calculation unit 110 calculates coordinate information of the test unit E and the aperture unit using a three-dimensional measurement technique such as a stereo method, and calculates the distance. You may measure. Alternatively, the user inputs the driving amount of the motor of the diaphragm unit 201 using the input unit 119 based on the image of the opening end of the test unit E and the diaphragm unit 201 displayed on the display unit 118, and the processing calculation unit To 110. Alternatively, for example, a sensor such as a fiber sensor may be separately provided to detect the distance between the test portion E and the open end.

  In step S201, the driving amount of the plurality of wings 202 of the diaphragm unit 201 is calculated based on the distance information between the test part E and the opening end measured in step S200, the motor of the diaphragm unit 201 is driven, and the diaphragm unit 201 is driven. Change the shape of the opening. It is preferable that the opening defined by the diaphragm portion 201 has an opening shape such that the gap between the test portion E and the diaphragm portion 201 is as small as possible.

  In step S202, the moving area S of the scanning stage 108 is set. The processing calculation unit 110 uses the calculation unit 111 to calculate the aperture shape of the diaphragm unit 201 from the driving amount of the diaphragm unit 201 calculated in step S201. Alternatively, the shape of the aperture of the diaphragm unit 201 is photographed by the imaging unit 113, and the aperture shape information of the diaphragm unit 201 is calculated from the image data generated by the processing calculation unit. Based on the calculated shape information, the movement area S of the scanning stage 108 is calculated, and the stage control unit 116 is set.

  As described above, according to the second embodiment, in addition to obtaining the same effects as those of the first embodiment, it is not necessary to attach and remove the throttle portion.

  Each of the above embodiments is merely illustrative, and various modifications may be made without departing from the technical idea of the present invention.

DESCRIPTION OF SYMBOLS 100 Object information acquisition apparatus 101, 101a, 101b Diaphragm | restriction part 102 Support stand 107 Support body 108 Scan stage 109 Transducer 110 Process calculating part 111 Calculation part 112 Storage part 116 Stage control part

Claims (14)

A light source;
A plurality of transducers for receiving an acoustic wave generated by irradiating the subject with light generated from the light source and outputting an electrical signal;
A support that supports the plurality of transducers such that the directional axes of the plurality of transducers are gathered;
A holding member for holding the subject, the holding member having an opening for inserting a test portion which is a part of the subject;
A moving part that moves at least one of the test part and the support so that a relative position between the test part and the support changes;
A moving area setting unit for setting a moving area of the moving unit;
An opening defining portion that defines the shape of the opening,
The subject information acquisition apparatus, wherein the moving region setting unit determines the moving region based on information related to the opening.   The object information acquiring apparatus according to claim 1, wherein the opening defining portion has a variable shape of the opening. The object information acquiring apparatus according to claim 2, wherein the opening defining unit changes a shape of the opening in accordance with a shape of the test part. It further has an imaging unit,
The said movement area setting part acquires the shape information of the opening prescribed | regulated by the said opening prescription | regulation part based on the signal output from the said imaging part, The any one of Claim 1 thru | or 3 characterized by the above-mentioned. Subject information acquisition apparatus. The imaging unit is at least one of the plurality of transducers;
The at least one transducer acquires shape information of an opening of the opening defining portion by transmitting an acoustic wave to the test portion and receiving a reflected wave of the acoustic wave. The subject information acquisition apparatus described.   The object information acquiring apparatus according to claim 1, further comprising an attachment portion to which the opening defining portion is detachably attached. A storage unit storing shape information of the opening defined by the opening defining unit;
The subject information according to claim 6, wherein the moving region setting unit sets the moving region by reading shape information corresponding to an opening defining portion attached to the attachment portion from the storage unit. Acquisition device. It further includes an input unit configured to allow a user to input information related to the opening defining unit attached to the attachment unit,
The said movement area | region setting part reads the shape information corresponding to the opening prescription | regulation part attached to the said attachment part from the said memory | storage part based on the information input from the said user. Subject information acquisition apparatus. A detection unit for detecting the type of the opening defining portion attached to the attachment portion;
The said movement area setting part reads the shape information corresponding to the opening prescription | regulation part attached to the said attachment part from the said memory | storage part based on the detection result by the said detection part, The said storage part is characterized by the above-mentioned. Subject information acquisition apparatus. A distance detection unit that detects a distance between the subject and the opening defining unit;
4. The object information acquisition apparatus according to claim 1, wherein opening shape information of the opening defining portion is acquired based on a detection result by the distance detection portion. 5. The moving region setting unit sets the moving region based on the shape of the opening defined by the opening defining unit and the arrangement of the plurality of transducers supported by the support. Item 4. The subject information acquiring apparatus according to any one of Items 1 to 3. A holding part for holding the test part;
The subject information acquiring apparatus according to claim 11, wherein the moving region setting unit further sets the moving region based on a shape of the holding unit. A plurality of transducers for receiving an acoustic wave generated by irradiating the subject with light and outputting an electrical signal;
A support that supports the plurality of transducers such that the directional axes of the plurality of transducers are gathered;
A holding member for holding the subject, the holding member having an opening for inserting a test portion which is a part of the subject;
A method for driving a subject information acquisition apparatus, comprising: a moving unit that moves at least one of the test unit and the support so that a relative position between the test unit and the support changes.
A method for driving a subject information acquiring apparatus, comprising: determining a moving region in which the moving unit moves based on information on the opening. The method for driving a subject information acquiring apparatus according to claim 13, wherein a distance between the opening and the test portion is information relating to the opening.

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