JP5769652B2 - Photoacoustic measuring device and photoacoustic measuring method - Google Patents

Description

  The present invention relates to a photoacoustic measurement apparatus and a photoacoustic measurement method used for examination and diagnosis of a subject using a photoacoustic analysis method.

  Conventionally, as a method for acquiring a tomographic image inside a subject, an ultrasonic image is generated by detecting ultrasonic waves reflected in the subject by irradiating the subject with ultrasonic waves. Ultrasonic imaging for obtaining a morphological tomographic image is known. On the other hand, in the examination of a subject, development of an apparatus that displays not only a morphological tomographic image but also a functional tomographic image has been advanced in recent years. One of such devices is a device using a photoacoustic analysis method. In this photoacoustic analysis method, light having a predetermined wavelength (for example, visible light, near-infrared light, or mid-infrared light) is irradiated to a subject as measurement light, and a specific substance in the subject is irradiated with the measurement light. A photoacoustic wave, which is an elastic wave generated as a result of absorbing energy, is detected, and the concentration of the specific substance is quantitatively measured. The specific substance in the subject is, for example, glucose or hemoglobin contained in blood. Such a technique for detecting a photoacoustic wave and generating a photoacoustic image based on the detection signal is called photoacoustic imaging (PAI) or photoacoustic tomography (PAT).

  Conventionally, in the photoacoustic measurement using the photoacoustic effect as described above, there are the following problems. The intensity of the measurement light is significantly attenuated by absorption and scattering in the process of propagating through the subject. In addition, the intensity of the photoacoustic wave generated in the subject based on the measurement light is also attenuated by absorption and scattering in the process of propagating in the subject. Therefore, in photoacoustic measurement, it is difficult to obtain information on the deep part of the subject. In order to solve this problem, for example, it is conceivable to increase the generated photoacoustic wave by increasing the amount of measurement light energy in the subject.

  However, when the subject is a living body, the maximum permissible exposure (MPE) per unit area that can be irradiated to the living body is determined in order not to damage the living tissue by the energy of the measurement light. ing. Therefore, even if the amount of light is increased, MPE becomes the upper limit.

  Therefore, as a method for suppressing the amount of light below MPE and detecting a photoacoustic wave having a high S / N, for example, as shown in Patent Document 1, measurement is performed using a bundle fiber including a plurality of optical fibers. A method of irradiating measurement light so that the light intensity distribution is uniform can be mentioned. For example, as shown in Patent Document 1, when a probe unit in which an optical system using a bundle fiber and an ultrasonic detection probe are combined together is used, the cord portion of the probe unit is flexible. Therefore, there is an advantage that the handling performance of the user is improved.

JP 2010-12295 A

  However, when the probe unit as described above is used, the handling performance is improved, but there is a problem that the measurement light is emitted in an unintended direction. In photoacoustic measurement, high-intensity measurement light is generally used to detect photoacoustic waves with sufficient intensity. Therefore, if measurement light is emitted in an unintended direction, for example, the measurement light enters a person's eyes and the person feels uncomfortable, or the measurement light is irradiated to a nearby measurement device and the device malfunctions. Or it may lead to an unexpected situation such as failure.

  The present invention has been made in view of the above problems, and in photoacoustic measurement using a probe unit, a photoacoustic measurement apparatus and a light that can reduce the possibility of measurement light being emitted in an unintended direction. The object is to provide an acoustic measurement method.

In order to solve the above-described problem, a first photoacoustic measurement device according to the present invention includes:
In a photoacoustic measuring apparatus that irradiates measurement light into a subject, detects a photoacoustic wave generated in the subject, converts the photoacoustic wave into an electrical signal, and performs photoacoustic measurement based on the electrical signal ,
A probe unit including a light irradiating unit for irradiating measurement light and an electroacoustic converting unit for converting a photoacoustic wave into an electrical signal;
An acquisition means for acquiring position coordinates and posture information in a space of the probe unit in real time, and acquiring position coordinates of a non-emission specific space that is a space where measurement light is not desired to be emitted;
Estimating means for estimating the orientation of the detection surface of the probe unit based on the posture information;
Determination means for determining whether or not measurement light may be emitted into the non-emission specific space based on the position coordinates of the probe unit, the orientation of the detection surface, and the position coordinates of the non-emission specific space;
Characterized in that it includes an avoidance measure means for taking measures to avoid a situation in which the measurement light is emitted into the non-emission specific space when the determination result that the above possibility is obtained by the above determination. It is.

  In the first photoacoustic measurement apparatus according to the present invention, the determination unit calculates a distance between a straight line extending in the above direction from the position coordinate of the probe unit and the position coordinate of the non-emission specific space, and the distance is predetermined. It is preferable to determine that the above possibility exists when the value is equal to or less than the threshold value.

  Alternatively, in the first photoacoustic measurement apparatus according to the present invention, the determination means includes a line connecting the position coordinates of the probe unit and the position coordinates of the non-emission specific space, and a straight line extending in the above direction from the position coordinates of the probe unit. It is preferable that the angle formed is calculated, and when the angle is equal to or smaller than a predetermined threshold, it is determined that the above possibility exists.

And in the 1st photoacoustic measuring device which concerns on this invention, when a judgment means judges that there exists the said possibility, it makes the stepwise judgment further according to the said high possibility. Yes,
It is preferable that the avoidance measure means changes the content of the measure in accordance with stepwise judgment.

  And in the 1st photoacoustic measuring device which concerns on this invention, it is preferable that an acquisition means acquires the position coordinate of non-release specific space in real time. Or in the 1st photoacoustic measuring device which concerns on this invention, an acquisition means shall acquire the position coordinate of the non-release specific space registered previously.

  In the first photoacoustic measurement apparatus according to the present invention, the avoidance measure means is such that the distance between the position coordinates of the probe unit and the position coordinates of the non-emission specific space is a predetermined distance or more, and the detection surface is an obstacle. If it is recognized that the measurement light is not emitted into the space due to contact with the light, no action can be taken regardless of the determination result by the determination means.

On the other hand, the second photoacoustic measurement device according to the present invention is:
In a photoacoustic measuring apparatus that irradiates measurement light into a subject, detects a photoacoustic wave generated in the subject, converts the photoacoustic wave into an electrical signal, and performs photoacoustic measurement based on the electrical signal ,
A probe unit including a light irradiating unit for irradiating measurement light and an electroacoustic converting unit for converting a photoacoustic wave into an electrical signal;
An acquisition means for acquiring the position coordinates in the space of this probe unit in real time and acquiring the position coordinates of a measurement place where photoacoustic measurement is desired,
A determination means for determining whether or not the position coordinates of the probe unit belong within a predetermined range based on the position coordinates of the measurement location;
It is characterized by comprising emission control means for emitting measurement light from the probe unit only when a determination result indicating that the position coordinates of the probe unit are within the predetermined range is obtained by the above determination. .

And in the 2nd photoacoustic measuring device concerning the present invention, an acquisition means acquires posture information in space of a probe unit in real time,
The judging means judges whether or not the posture information belongs within a predetermined range based on the measurement specific posture of the probe unit.
It is preferable that the emission control means emits measurement light only when a determination result that the posture information belongs to the predetermined range is further obtained.

Furthermore, the first photoacoustic measurement method according to the present invention includes:
Photoacoustic generated in the subject by irradiating the subject with the measuring light using a probe unit that includes a light irradiating unit that irradiates the measuring light and an electroacoustic converting unit that converts the photoacoustic wave into an electrical signal. In a photoacoustic measurement method for detecting a wave, converting the photoacoustic wave into an electrical signal, and performing photoacoustic measurement based on the electrical signal,
Obtain the position coordinates and orientation information in space of this probe unit in real time,
Obtain the position coordinates of the non-emission specific space that is the space you do not want to emit the measurement light,
Estimate the orientation of the detection surface of the probe unit based on the posture information,
Based on the position coordinates of the probe unit, the orientation of the detection surface, and the position coordinates of the non-emission specific space, a determination is made as to whether or not measurement light may be emitted into the non-emission specific space,
In the case where a determination result indicating that there is the above possibility is obtained by the above determination, a measure is taken to avoid a situation in which the measurement light is emitted into the non-emission specific space.

  In the first photoacoustic measurement method according to the present invention, the distance between the straight line extending in the above direction from the position coordinate of the probe unit and the position coordinate of the non-emission specific space is calculated, and this distance is equal to or less than a predetermined threshold value. In some cases, it is preferable to determine that the above possibility exists.

  Alternatively, in the first photoacoustic measurement method according to the present invention, an angle formed by a line connecting the position coordinates of the probe unit and the position coordinates of the non-emission specific space and a straight line extending in the above direction from the position coordinates of the probe unit is calculated. However, it is preferable that when the angle is equal to or smaller than a predetermined threshold, it is determined that the above possibility exists.

Then, in the first photoacoustic measurement method according to the present invention, when it is determined that there is the possibility, a stepwise determination is further made according to the high possibility.
It is preferable to change the content of the measure according to this stepwise determination.

  And in the 1st photoacoustic measuring method which concerns on this invention, it is preferable to acquire the position coordinate of non-release specific space in real time. Or in the 1st photoacoustic measuring method which concerns on this invention, the position coordinate of the non-release specific space registered previously can be acquired.

  In the first photoacoustic measurement method according to the present invention, the distance between the position coordinates of the probe unit and the position coordinates of the non-emission specific space is a predetermined distance or more, and the detection surface is in contact with the obstacle. Therefore, when it is recognized that the measurement light is not emitted into the space, it is possible to prevent the measure from being taken regardless of the determination result by the determination means.

On the other hand, the second photoacoustic measurement method according to the present invention is:
Photoacoustic generated in the subject by irradiating the subject with the measuring light using a probe unit that includes a light irradiating unit that irradiates the measuring light and an electroacoustic converting unit that converts the photoacoustic wave into an electrical signal. In a photoacoustic measurement method for detecting a wave, converting the photoacoustic wave into an electrical signal, and performing photoacoustic measurement based on the electrical signal,
Obtain the position coordinates of this probe unit in space in real time,
Obtain the position coordinates of the measurement location where you want to perform photoacoustic measurement,
Determine whether the position coordinates of the probe unit belong within a predetermined range based on the position coordinates of the measurement location,
The measurement light is emitted from the probe unit only when the determination result that the position coordinates of the probe unit belong to the predetermined range is obtained.

In the second photoacoustic measurement method according to the present invention, whether the posture information belongs to a predetermined range based on the measurement specific posture of the probe unit based on the posture information in the probe unit space acquired in real time. Make a decision,
It is preferable to emit the measurement light only when a determination result that the posture information belongs to the predetermined range is further obtained.

  In particular, the first photoacoustic measurement apparatus according to the present invention acquires position coordinates and posture information in the space of the probe unit in real time, and acquires position coordinates of a non-emission specific space that is a space where measurement light is not desired to be emitted. Obtaining means, estimating means for estimating the orientation of the detection surface of the probe unit based on posture information, and the non-emission specific space based on the position coordinates of the probe unit, the orientation of the detection surface, and the position coordinates of the non-emission specific space When the determination means for determining whether or not there is a possibility of measurement light being emitted and the determination result that there is the possibility of the above is obtained by the above determination, the measurement light is emitted into the non-emission specific space And an avoidance measure means for taking measures to avoid the problem. According to the present invention, the geometric positional relationship between the direction of the detection surface of the probe unit (that is, the direction in which the measurement light is most likely to be emitted in an unintended direction) and the non-emission specific space. Can be determined in real time. As a result, in the photoacoustic measurement using the probe unit, it is possible to reduce the possibility that the measurement light is emitted in an unintended direction.

  In particular, the second photoacoustic measurement apparatus according to the present invention acquires the position coordinates in the space of the probe unit in real time, acquires the position coordinates of the measurement place where the photoacoustic measurement is desired, and the position of the measurement place. A determination means for determining whether or not the position coordinates of the probe unit belong within a predetermined range with reference to the coordinates, and the determination result that the position coordinates of the probe unit belong to the predetermined range is obtained by the above determination. Only in this case, it is characterized by comprising emission control means for emitting measurement light from the probe unit. According to the present invention, it is possible to determine in real time whether or not a probe unit exists within a predetermined range with respect to a measurement location, and measurement light can be emitted from the probe unit only when necessary. As a result, in the photoacoustic measurement using the probe unit, it is possible to reduce the possibility that the measurement light is emitted in an unintended direction.

  Further, the first photoacoustic measurement method according to the present invention particularly acquires the position coordinates and orientation information of the probe unit in the space in real time, and the position coordinates of the non-emission specific space which is a space where the measurement light is not desired to be emitted. The direction of the detection surface of the probe unit is estimated based on the posture information, and the measurement light is transmitted to the non-emission specific space based on the position coordinate of the probe unit, the direction of the detection surface, and the position coordinate of the non-emission specific space. Judgment is made whether there is a possibility of being emitted, and measures are taken to avoid a situation in which measuring light is emitted into a non-emission specific space when the above judgment results in the judgment that there is the possibility of the above. It is characterized by. As a result, in the photoacoustic measurement using the probe unit, it is possible to reduce the possibility that the measurement light is emitted in an unintended direction.

  In addition, the second photoacoustic measurement method according to the present invention particularly acquires the position coordinates of the probe unit in the space in real time, acquires the position coordinates of the measurement place where the photoacoustic measurement is to be performed, and obtains the position coordinates of the measurement place. Only when the determination result that the position coordinates of the probe unit belong to the predetermined range is obtained by the above determination, whether or not the position coordinates of the probe unit belong to the predetermined range with reference to The measurement light is emitted from the probe unit. As a result, in the photoacoustic measurement using the probe unit, it is possible to reduce the possibility that the measurement light is emitted in an unintended direction.

It is the schematic which shows a mode that a subject is examined using the photoacoustic measuring device of this invention. It is the schematic which shows the structure of 1st Embodiment of a photoacoustic measuring device. It is a block diagram which shows the structure of the image generation part in FIG. It is a block diagram which shows the structure of the avoidance judgment part in FIG. It is the schematic which shows the example of the method of determining the presence or absence of possibility of measurement light being discharge | released to non-release specific space. It is the schematic which shows the other example of the method of determining the presence or absence of possibility of measurement light being discharge | released to non-release specific space. It is the schematic which shows the structure of 2nd Embodiment of a photoacoustic measuring device. It is a block diagram which shows the structure of the discharge | release judgment part in FIG. It is the schematic which shows the example of the method of determining whether the position coordinate of a probe unit belongs to the predetermined range on the basis of the position coordinate of a measurement place. It is the schematic which shows the example of the method of determining whether the attitude | position information of a probe unit belongs in the predetermined range on the basis of the measurement specific attitude | position.

  Hereinafter, although an embodiment of the present invention is described using a drawing, the present invention is not limited to this. In addition, for easy visual recognition, the scale of each component in the drawings is appropriately changed from the actual one.

“First Embodiment of Photoacoustic Measuring Device”
First, a first embodiment of the photoacoustic measurement device will be described. The photoacoustic measuring device of this embodiment is the photoacoustic imaging device 10 which can produce | generate a photoacoustic image, for example. FIG. 1 is a schematic diagram showing how a subject is examined using the photoacoustic imaging apparatus 10 of the present embodiment. FIG. 2 is a schematic diagram illustrating the configuration of the photoacoustic imaging apparatus 10. FIG. 3 is a block diagram showing a configuration of the image generation unit in FIG. FIG. 4 is a block diagram illustrating a configuration of the avoidance determination unit 8a in FIG.

  As shown in FIGS. 1 and 2, the photoacoustic imaging apparatus 10 according to the present embodiment generates a laser beam L including a specific wavelength component as measurement light, and irradiates the subject 7 with the laser beam L. An image generation unit 2 that generates photoacoustic image data of an arbitrary cross section by detecting a photoacoustic wave U generated in the subject 7 by irradiating the subject 7 with the laser light L; and an acoustic signal; An electroacoustic conversion unit 3 that converts an electric signal, a display unit 6 that displays the photoacoustic image data, an operation unit 5 for an operator to input patient information and imaging conditions of the apparatus, and an avoidance determination unit 8a And a system control unit 4 for comprehensively controlling these units.

  On the other hand, the photoacoustic imaging method in the present embodiment uses a probe unit 70 including a light irradiation unit 1 that irradiates laser light L and an electroacoustic conversion unit 3 that converts a photoacoustic wave U into an electrical signal, and laser light. The position coordinates of the non-release specific space, which is a space where L is not desired to be released, are acquired and set, the position coordinates and posture information in the space of the probe unit 70 are acquired in real time, and the probe unit 70 is based on the posture information. The direction of the detection surface is estimated, and based on the position coordinates of the probe unit 70, the direction of the detection surface, and the position coordinates of the non-emission specific space, it is determined whether or not measurement light may be emitted into the non-emission specific space. If the above determination results in the determination that the above possibility exists, take measures to avoid the situation in which the laser light L is emitted into the non-emission specific space. In this case, the subject 7 is irradiated with the laser light L, the photoacoustic wave U generated in the subject 7 is detected, the photoacoustic wave U is converted into an electrical signal, and light is generated based on the electrical signal. It performs acoustic measurement.

  The non-emission specific space is, for example, a space including a specific object that should avoid an unexpected situation caused by laser light (measurement light). Hereinafter, in this embodiment, the case where the non-release specific space is set as a space near the head of the subject 7 will be described as an example.

  In the present embodiment, the probe unit 70 includes the electroacoustic conversion unit 3, the light irradiation unit 15, and the magnetic sensor 82.

  The optical transmission unit 1 includes, for example, a light source unit 11 including a plurality of light sources that output laser beams L having different wavelengths, an optical combining unit 12 that combines the laser beams L having a plurality of wavelengths on the same optical axis, and the laser. A multi-channel waveguide unit 14 that guides the light L to the body surface of the subject 7, an optical scanning unit 13 that performs scanning by switching channels used in the waveguide unit 14, and a laser supplied by the waveguide unit 14 A light irradiator 15 that emits light L toward the imaging region of the subject 7.

The light source unit 11 includes, for example, one or more light sources that generate light having a predetermined wavelength. As the light source, a light emitting element such as a semiconductor laser (LD), a solid-state laser, or a gas laser that generates a specific wavelength component or monochromatic light including the component can be used. The light source unit 11 preferably outputs pulsed light having a pulse width of 1 to 100 nsec as laser light. The wavelength of the laser light is appropriately determined according to the light absorption characteristics of the substance in the subject to be measured. Although hemoglobin in a living body has different optical absorption characteristics depending on its state (oxygenated hemoglobin, deoxygenated hemoglobin, methemoglobin, carbon dioxide hemoglobin, etc.), it generally absorbs light of 600 nm to 1000 nm. Therefore, for example, when the measurement target is hemoglobin in a living body (that is, when a blood vessel is imaged), it is generally preferable to set the thickness to about 600 to 1000 nm. Further, from the viewpoint of reaching the deep part of the subject 7, the wavelength of the laser light is preferably 700 to 1000 nm, and particularly preferably a near infrared wavelength (wavelength of 700 to 850 nm). The output of the laser beam is 10 μJ / cm ² to several tens of mJ / cm ² from the viewpoints of propagation loss of laser beam and photoacoustic wave, efficiency of photoacoustic conversion, detection sensitivity of the current detector, and the like. Is preferred. Further, the repetition of the pulsed light output is preferably 10 Hz or more from the viewpoint of the image construction speed. Further, the laser beam may be a pulse train in which a plurality of the above pulsed beams are arranged.

  More specifically, for example, when the hemoglobin concentration of the subject 7 is measured, an Nd: YAG laser (emission wavelength: about 1000 nm) which is a kind of solid-state laser, or a He—Ne gas laser (emission light) which is a kind of gas laser. A laser beam having a pulse width of about 10 nsec is formed using a wavelength of 633 nm. When a small light emitting element such as an LD is used, a material such as InGaAlP (emission wavelength: 550 to 650 nm), GaAlAs (emission wavelength: 650 to 900 nm), InGaAs or InGaAsP (emission wavelength: 900 to 2300 nm) is used. Can be used. Recently, a light-emitting element using InGaN that emits light with a wavelength of 550 nm or less is becoming available. Furthermore, an OPO (Optical Parametrical Oscillators) laser using a nonlinear optical crystal whose wavelength is variable can be used.

  The optical multiplexing unit 12 is for superimposing laser beams having different wavelengths generated from the light source unit 11 on the same optical axis. Each laser beam is first converted into parallel rays by a collimating lens, and then the optical axis is adjusted by a right-angle prism or a dichroic prism. With such a configuration, a relatively compact multiplexing optical system can be obtained. Also, a commercially available multiple wavelength multiplexer / demultiplexer developed for optical communication may be used. Further, when a light source such as an OPO laser whose wavelength can be continuously changed is used for the light source unit 11, the optical multiplexing unit 12 is not necessarily required.

  The waveguide unit 14 is for guiding the light output from the optical multiplexing unit 12 to the light irradiation unit 15. In order to carry out efficient light propagation, it is preferable to use an optical fiber, a thin-film optical waveguide or a light guide plate. In the present embodiment, the waveguide section 14 is composed of a plurality of optical fibers. A predetermined optical fiber is selected from the plurality of optical fibers, and the subject 7 is irradiated with laser light by the selected optical fiber. Although not clearly shown in FIG. 2, it can be used together with an optical system such as an optical filter or a lens.

  The optical scanning unit 13 supplies light while sequentially selecting a plurality of optical fibers arranged in the waveguide unit 14. Thereby, the subject 7 is scanned with light.

  The electroacoustic conversion unit 3 includes a plurality of minute conversion elements 54 arranged in a one-dimensional or two-dimensional manner, for example. The conversion element 54 is a piezoelectric element made of a polymer film such as piezoelectric ceramics or polyvinylidene fluoride (PVDF). The electroacoustic conversion unit 3 receives the photoacoustic wave U generated in the subject by the light irradiation from the light irradiation unit 15. The conversion element 54 has a function of converting the photoacoustic wave U into an electric signal at the time of reception. The electroacoustic conversion unit 3 is configured to be small and light, and is connected to a receiving unit 22 described later by a multi-channel cable. The electroacoustic conversion unit 3 is selected according to the diagnostic region from among sector scanning, linear scanning, convex scanning, and the like. The electroacoustic conversion unit 3 may include an acoustic matching layer in order to efficiently transmit the photoacoustic wave U. In general, the acoustic impedance of the piezoelectric element material and the living body are greatly different. Therefore, when the piezoelectric element material and the living body are in direct contact with each other, reflection at the interface is increased and the photoacoustic wave U cannot be efficiently transmitted. For this reason, the photoacoustic wave U can be efficiently transmitted by arranging an acoustic matching layer having an intermediate acoustic impedance between the piezoelectric element material and the living body. Examples of the material constituting the acoustic matching layer include epoxy resin and quartz glass.

  The image generation unit 2 of the photoacoustic imaging apparatus 10 selectively drives the plurality of conversion elements 54 constituting the electroacoustic conversion unit 3 and gives a predetermined delay time to the electric signal from the electroacoustic conversion unit 3 to adjust the electric signal. A receiving unit 22 that generates a received signal by performing phase addition, a scanning control unit 24 that controls the selection drive of the conversion element 54 and the delay time of the receiving unit 22, and various types of received signals obtained from the receiving unit 22 And a signal processing unit 25 for performing the above processing.

  As illustrated in FIG. 3, the reception unit 22 includes an electronic switch 53, a preamplifier 55, a reception delay circuit 56, and an adder 57.

  When receiving the photoacoustic wave in the photoacoustic scanning, the electronic switch 53 selects a predetermined number of adjacent conversion elements 54. For example, when the electroacoustic conversion unit 3 is composed of 192 conversion elements CH1 to CH192 of the array type, such an array conversion element is converted into an area 0 (area of conversion elements from CH1 to CH64) by the electronic switch 53. ), Area 1 (region of the conversion element from CH65 to CH128) and area 2 (region of the conversion element from CH129 to CH192) are handled by being divided. When an array type conversion element composed of N conversion elements in this way is handled as a group (area) of n (n <N) adjacent transducers, and an imaging operation is performed for each area, It is not necessary to connect preamplifiers or A / D conversion boards to the conversion elements of all channels, the structure of the probe unit 70 can be simplified, and an increase in cost can be prevented. In addition, when a plurality of optical fibers are arranged so that each area can be individually irradiated with light, the light output per time does not need to be increased, so an expensive light source with a large output is used. There is also an advantage that it is not necessary. Each electric signal obtained by the conversion element 54 is supplied to the preamplifier 55.

  The preamplifier 55 amplifies a minute electric signal received by the conversion element 54 selected as described above, and ensures a sufficient S / N.

  The reception delay circuit 56 forms a converged reception beam by matching the phase of the photoacoustic wave U from a predetermined direction with the electrical signal of the photoacoustic wave U obtained from the conversion element 54 selected by the electronic switch 53. Give a delay time to do.

  The adder 57 adds together the electrical signals of a plurality of channels delayed by the reception delay circuit 56 to combine them into one reception signal. By this addition, phasing addition of acoustic signals from a predetermined depth is performed, and a reception convergence point is set.

  The scanning control unit 24 includes a beam focusing control circuit 67 and a conversion element selection control circuit 68. The conversion element selection control circuit 68 supplies position information of a predetermined number of conversion elements 54 at the time of reception selected by the electronic switch 53 to the electronic switch 53. On the other hand, the beam focusing control circuit 67 supplies delay time information for forming reception convergence points formed by a predetermined number of conversion elements 54 to the reception delay circuit 56.

  The signal processing unit 25 includes a filter 66, a signal processor 59, an A / D converter 60, and an image data memory 62. The electrical signal output from the adder 57 of the receiving unit 22 removes unnecessary noise in the filter 66 of the signal processing unit 25, and thereafter, the signal processor 59 performs logarithmic conversion of the amplitude of the received signal to make the weak signal relative. Stress. In general, the received signal from the subject 7 has an amplitude with a wide dynamic range of 80 dB or more, and a weak signal is emphasized in order to display it on a normal monitor having a dynamic range of about 23 dB. Amplitude compression is required. The filter 66 has a band pass characteristic, and has a mode for extracting a fundamental wave in a received signal and a mode for extracting a harmonic component. The signal processor 59 performs envelope detection on the logarithmically converted received signal. The A / D converter 60 A / D converts the output signal of the signal processor 59 to form photoacoustic image data for one line. The photoacoustic image data for one line is stored in the image data memory 62.

  The image data memory 62 is a storage circuit that sequentially stores the photoacoustic image data for one line generated as described above. The system control unit 4 reads out data for one line of a certain section stored in the image data memory 62 and necessary for generating a one-frame photoacoustic image. The system control unit 4 combines the data for one line while spatially interpolating to generate photoacoustic image data for one frame of the cross section. Then, the system control unit 4 stores the photoacoustic image data for one frame in the image data memory 62.

  The display unit 6 includes a display image memory 63, a photoacoustic image data converter 64, and a monitor 65. The display image memory 63 is a buffer memory that reads photoacoustic image data for one frame to be displayed on the monitor 65 from the image data memory 62 and temporarily stores it. The photoacoustic image data converter 64 performs D / A conversion and television format conversion on the photoacoustic image data for one frame stored in the display image memory 63, and the output is displayed on the monitor 65.

  The operation unit 5 includes a keyboard, a trackball, a mouse, and the like on the operation panel, and is used by an apparatus operator to input necessary information such as patient information, imaging conditions of the apparatus, and a display section.

  The avoidance determination unit 8a detects information in the space of the probe unit using the magnetic sensor 82 provided in the probe unit 70 in order to avoid a situation in which laser light is emitted into the non-emission specific space. And processing of information necessary for grasping the positional relationship between the non-release specific space and whether or not the situation can occur is determined. The avoidance determination unit 8a includes a magnetism generation unit 83 that generates magnetism in space, an information acquisition unit 81, and a determination unit 84a.

  The magnetic sensor 82 and the magnetic generator 83 constitute a three-dimensional magnetic sensor unit for acquiring information in the space of the probe unit 70. In the present embodiment, the three-dimensional magnetic sensor unit, a first information receiving unit 85 and a second information receiving unit 86a described later function as acquisition means in the present invention as a whole. The three-dimensional magnetic sensor unit has a relative position coordinate (x, y, z) of the magnetic sensor 82 with respect to the magnetic generator 83 in the space on the pulse magnetic field formed by the magnetic generator 83, and posture information ( The angle (information of α, β, γ) can be acquired. In this embodiment, two magnetic sensors 82 are mounted on the probe unit 70, and the posture information of the probe unit 70 can be calculated from the position coordinates and posture information of each magnetic sensor 82. The posture information of the probe unit 70 is, for example, information on the state of the probe unit 70 in the xyz-axis space with the magnetic generator 83 as the origin, and particularly includes information on tilt and rotation from the reference state in the space. . The location of the magnet generator 83 is not particularly limited, and may be anywhere as long as the range in which the probe unit 70 is operated is included in the magnetic field space formed by the magnet generator 83.

  As shown in FIG. 4, the information acquisition unit 81 includes a first information reception unit 85, a second information reception unit 86 a, and an estimation unit 87.

  The first information receiving unit 85 receives position coordinates and posture information in the space of the probe unit 70 from the magnetic sensor 82 in real time. Using the three-dimensional magnetic sensor unit as described above, the first information receiving unit 85 receives in real time the position coordinates and posture information in the space of the probe unit 70 included in the signals of the two magnetic sensors 82. For the position coordinates in the space of the probe unit 70, for example, one of the two obtained by the two magnetic sensors 82 is selected, the average value thereof is adopted, or the other two magnetic sensors 82 have a predetermined relationship. Position can be adopted. In the present embodiment, a case will be described in which the position of the probe unit 70 in the space is a position having a predetermined relationship from the two magnetic sensors 82 and the position of the center of the detection surface of the probe unit 70 is employed. The position coordinates and the posture information received by the first information receiving unit 85 are sent to the estimation unit 87.

  The second information receiving unit 86a receives the position coordinates of the non-release specific space. In the present embodiment, the second information receiving unit 86a receives, from the system control unit 4, position coordinates registered in advance for the head of the subject 7 in the space, for example, as position coordinates of the non-release specific space. In the present embodiment, the position coordinates of the head are registered in advance in the system control unit 4, and the second information receiving unit 86a acquires the registered position coordinates. Such a method is effective when the movement of the subject 7 is small. For example, the magnetic sensor 82 of the probe unit 70 is arranged in the vicinity of the head so that the initial setting can be performed with a switch or the like. It may be set manually. In addition, the position coordinates of the head can be acquired in real time in the same manner as the position coordinates of the probe unit 70 by attaching another magnetic sensor to the head. Such a method is effective when the subject 7 moves a lot. The position coordinates for the head are, for example, eye position coordinates. This is to more accurately determine whether or not the measurement light may be emitted into the non-emission specific space. In the present invention, it is not necessary to strictly define the contour of the non-emission specific space, and the position of the representative point included in the approximate region to be set as the non-emission specific space (in this embodiment, the eye of the head) It is sufficient to set the position. The extent to which the non-emission specific space is set is appropriately set according to a determination criterion in the determination unit 84a described later.

  And the estimation part 87 functions as an estimation means of this invention, and estimates the direction of the detection surface of the probe unit 70 based on attitude | position information. It can be said that the direction of the detection surface of the probe unit 70 is a direction in which laser light is mainly emitted. Therefore, the direction of the detection surface of the probe unit 70 is estimated to be the direction in which the laser beam L is most likely to be emitted in an unintended direction. The direction of the detection surface of the probe unit 70 can be, for example, a normal direction facing the outside of the probe unit 70 at the center of the detection surface.

  As a result, the information acquisition unit 81 finally acquires the position coordinates of the probe unit 70 in the space, the orientation of the detection surface of the probe unit, and the position coordinates of the non-emission specific space. Then, the information acquisition unit 81 transmits these three pieces of information to the determination unit 84a.

  Based on the three pieces of information acquired by the information acquisition unit 81, the determination unit 84a determines whether or not there is a possibility of laser light being emitted into the non-release specific space. The determination of the possibility is made as follows, for example.

  FIG. 5A is a schematic diagram illustrating an example of a method for determining whether or not there is the possibility. In the case shown in FIG. 5A, the distance y between the straight line L1 extending from the position coordinate P1 of the probe unit 70 in the direction of the detection surface 3s and the position coordinate P2 of the non-emission specific space R1 is calculated, and this distance y is a predetermined threshold value. In the following cases, a determination is made that the above possibility exists. The distance between the straight line extending in the above-described direction and the position coordinates of the non-emission specific space R1 means the geometrical shortest distance. Here, the predetermined threshold regarding this distance y is set suitably.

  Further, in the case of the laser light L radiated with a divergence angle, the following method is effective. FIG. 5B is a schematic diagram illustrating another example of a method for determining whether or not the above-described possibility exists. In the case shown in FIG. 5B, a line L2 connecting the position coordinate P1 of the probe unit 70 and the position coordinate P2 of the non-release specific space R1 and a straight line L1 extending from the position coordinate P1 of the probe unit 70 toward the detection surface 3s are formed. When the angle θ is calculated and the angle θ is equal to or smaller than a predetermined threshold, it is determined that the above possibility exists. Here, the predetermined threshold regarding this angle (theta) is set suitably.

  For example, the determination unit 84a determines that there is the possibility according to the difference between the distance y or the angle θ and the predetermined threshold, and then determines according to the possibility. Stage setting may be performed. Then, the determination result obtained by the determination unit 84 a is transmitted to the system control unit 4.

  The system control unit 4 includes a CPU (not shown) and a storage circuit (not shown), and controls each unit such as the optical transmission unit 1, the image generation unit 2, and the display unit 6 and controls the entire system according to a command signal from the operation unit 5. Supervised. In particular, the input command signal of the operator sent via the operation unit 5 is stored in the internal CPU. Further, the system control unit 4 also functions as an avoidance measure of the present invention, and when the determination unit 84a obtains a determination result indicating that there is the above possibility, the laser light is emitted into the non-emission specific space R1. Take measures to avoid the situation. As such measures, for example, the output of the laser light L is stopped by the light source unit 11, a warning screen is displayed on the display unit 6, or a sound or light for notifying a warning is given. When there is a stage setting in the judgment result, an avoidance measure corresponding to the stage can be taken. For example, when the possibility is high, the output of the laser light L is immediately stopped by the light source unit 11, while when the possibility is low, only a warning sound is used.

  In the system control unit 4, the distance between the position coordinate P1 of the probe unit 70 and the position coordinate P2 of the non-emission specific space R1 is a predetermined distance (for example, 10 cm) or more, and the detection surface is in contact with an obstacle. If it is recognized that the laser beam L is not emitted into the space, it can be set so that no action is taken regardless of the determination result by the determination means. Actually, for example, even when the criteria as described in FIGS. 5A and 5B are simply satisfied, there is no possibility of the above, or when the operation of the probe unit 70 is necessary (for example, the back of the head or the lower jaw). This is because there may be a case where a part is inspected. With such a setting, it is possible to take measures to avoid a situation in which laser light is emitted into the non-emission specific space R1 more flexibly. Here, the reason why the lower limit of the predetermined distance is 10 cm is that the diffusion distance of the laser light in the living body is about 5 cm at the most, so even if, for example, the examination of the occipital region or the lower jaw is performed, it may be 10 cm away. This is because the laser light is considered not to reach the eyeball or the fundus. If the setting as described above is performed, for example, when the occipital region and the mandibular region are inspected, it is possible to eliminate a situation in which the avoidance measure mechanism operates and the inspection cannot be performed. In addition, it can be determined whether or not the detection surface is in contact with an obstacle by performing, for example, ultrasonic image analysis as needed.

  As described above, according to the present invention, the geometrical relationship between the direction of the detection surface of the probe unit (that is, the direction in which the measurement light is most likely to be emitted in an unintended direction) and the non-emission specific space. It is possible to determine a real positional relationship in real time. As a result, in the photoacoustic measurement using the probe unit, it is possible to reduce the possibility that the measurement light is emitted in an unintended direction.

  If it is desired to protect the eyes of a person other than the subject (for example, an examiner and an inspection observer), the position coordinates of the eyes of the person other than the subject are acquired in the same manner. Then, it is easy to take a similar avoidance measure and expand so as to avoid the situation where the measurement light is emitted for each person. In addition, in order to prevent malfunction or failure of equipment with an optical sensor that is in the same closed space (for example, an examination room) as the probe unit, the position of the equipment should be such that high-intensity measurement light does not enter the optical sensor. Expansion such as setting coordinates in advance is also easy. For example, as such a device, a device including an infrared sensor light receiving unit used for position and orientation control of other devices, a device including a remote control receiving unit, and the like can be given.

  Further, the specific object that should avoid the unexpected situation caused by the measurement light may be the space itself. For example, if a space with a lot of people is set, the possibility that an unexpected situation occurs for a person can be further reduced.

“Second Embodiment of Photoacoustic Measuring Device”
Next, a second embodiment of the photoacoustic measurement apparatus will be described. The photoacoustic measuring device of this embodiment is also the photoacoustic imaging device 10 which can generate a photoacoustic image, for example. FIG. 6 is a schematic diagram illustrating the configuration of the photoacoustic imaging apparatus 10. FIG. 7 is a block diagram showing a configuration of the release determination unit 8b in FIG.

  As shown in FIG. 6, the photoacoustic imaging apparatus 10 according to the present embodiment includes an optical transmission unit 1, an image generation unit 2, an electroacoustic conversion unit 3, a display unit 6, an operation unit 5, and a release determination. A unit 8b and a system control unit 4 for comprehensively controlling these units. That is, the photoacoustic imaging apparatus 10 of the present embodiment is different from the photoacoustic measurement apparatus of the first embodiment in that it includes an emission determination unit 8b instead of the avoidance determination unit 8a. Therefore, a detailed description of the same configuration as that of the first embodiment is omitted unless necessary.

  On the other hand, the photoacoustic imaging method according to the present embodiment uses a probe unit 70 including a light irradiation unit 1 that irradiates a laser beam L and an electroacoustic conversion unit 3 that converts a photoacoustic wave U into an electric signal. The position coordinates of the measurement location to be measured are acquired and set, the position coordinates and posture information in the space of the probe unit 70 are acquired in real time, and the direction of the detection surface of the probe unit 70 is estimated based on the posture information. Based on the position coordinates of the probe unit 70, the orientation of the detection surface, and the position coordinates of the measurement location, it is determined whether or not the position coordinates of the probe unit 70 belong to a predetermined range based on the position coordinates of the measurement location (position If the determination result that the position coordinates of the probe unit 70 belong to the predetermined range is obtained by the above determination. Only performs photoacoustic measurement by emitting a laser beam L from the probe unit 70, in other cases, those which do not emit the laser beam L from the probe unit 70.

  The measurement location is, for example, a part of the subject that is desired to capture a photoacoustic image by irradiating laser light (measurement light). Hereinafter, in this embodiment, a case where the measurement location is set to the chest of the subject 7 will be described as an example.

  The probe unit 70, the optical transmission unit 1, the image generation unit 2, the electroacoustic conversion unit 3, the display unit 6, and the operation unit 5 are the same as those in the photoacoustic imaging apparatus according to the first embodiment.

  The emission determination unit 8b uses a magnetic sensor 82 provided in the probe unit 70 to emit the laser beam L only when the position coordinate of the probe unit 70 belongs to a predetermined range with reference to the position coordinate of the measurement location. Using this, information in the space of the probe unit is detected, processing of information necessary for grasping the positional relationship between the probe unit 70 and the measurement place, and determination of belonging to the position coordinates. The release determination unit 8b includes a magnetism generation unit 83 that generates magnetism in space, an information acquisition unit 81, and a determination unit 84b.

  The magnetic sensor 82 and the magnetism generator 83 are the same as in the case of the photoacoustic imaging apparatus in the first embodiment.

  As shown in FIG. 7, the information acquisition unit 81 includes a first information reception unit 85, a second information reception unit 86b, and an estimation unit 87.

  The 1st information receiving part 85 is the same as that of the case of the photoacoustic imaging device in 1st Embodiment.

  The second information receiving unit 86b receives the position coordinates of the measurement location. In the present embodiment, the second information receiving unit 86b receives, from the system control unit 4, position coordinates registered in advance for the chest of the subject 7 in the space, for example, as the position coordinates of the measurement location. In the present embodiment, the position coordinates of the chest are registered in advance in the system control unit 4, and the second information receiving unit 86b acquires the registered position coordinates. Such a method is effective when the movement of the subject 7 is small. For example, the magnetic sensor 82 of the probe unit 70 is arranged in the vicinity of the chest so that it can be initialized by a switch or the like, or manually by the operation unit 5. You may make it set with. In addition, the position coordinates of the chest can be acquired in real time in the same manner as the position coordinates of the probe unit 70 by attaching another magnetic sensor to the chest. Such a method is effective when the subject 7 moves a lot. The position coordinates for the chest are, for example, the position coordinates of the representative point of the area. In the present invention, it is not necessary to strictly define the contour of the measurement place, and it is sufficient to set the position of the representative point included in the approximate region to be set as the measurement place.

  The estimation part 87 is the same as that of the photoacoustic imaging device in 1st Embodiment.

  As a result, the information acquisition unit 81 finally acquires the position coordinates of the probe unit 70 in the space, the orientation of the detection surface of the probe unit, and the position coordinates of the measurement location. Then, the information acquisition unit 81 transmits these three pieces of information to the determination unit 84b.

  Based on the three pieces of information acquired by the information acquisition unit 81, the determination unit 84b determines whether the position coordinates belong. The affiliation determination with respect to the position coordinates is performed as follows, for example.

  FIG. 8A is a schematic diagram illustrating an example of a method for determining whether a position coordinate belongs. In the case shown in FIG. 8A, the distance between the position coordinate P1 of the probe unit 70 and the position coordinate P3 of the measurement area is calculated, and when this distance is equal to or less than a predetermined threshold value r, the probe unit is within the predetermined range R2. A determination is made that 70 position coordinates belong. Here, the predetermined threshold value r relating to this distance is preferably about 10 cm, for example, but is appropriately set in consideration of actual measurement conditions and the like.

  Further, the determination unit 84b determines whether or not the posture information belongs to a predetermined range based on the preset measurement specific posture of the probe unit 70 in addition to the above-described determination of whether or not the position coordinate belongs. It may also be possible to determine whether or not the position information belongs. For example, the affiliation determination for the posture information is performed as follows, for example. FIG. 8B is a schematic diagram illustrating an example of a method for determining whether or not a pose belongs to posture information. The measurement specific posture is a posture that serves as a reference for the posture of the probe unit 70 that should emit the measurement light, and is usually an ideal posture of the probe unit that performs photoacoustic measurement. It is set in advance before performing photoacoustic measurement. For example, this setting may be performed by setting the probe unit 70 on the chest in an attitude for actually performing photoacoustic sound measurement and performing initial setting with a switch or the like, or setting manually with the operation unit 5. Then, an angle φ formed by the detection surface orientation 71a of the probe unit 71 in the measurement specific posture and the actual detection surface orientation 70a of the probe unit 70 (for example, an angle when intersecting at the point P1) is obtained. When φ is equal to or less than a predetermined threshold value, a determination is made that the posture information belongs within a predetermined range based on the measured specific posture. Here, the predetermined threshold value related to the angle φ is preferably set to about 45 °, for example, but is appropriately set in consideration of actual measurement conditions and the like.

  The system control unit 4 also functions as the emission control unit of the present invention, and the laser light L is emitted from the probe unit 70 only when the determination unit 84b obtains the determination result of the affiliation determination regarding the position coordinates and the posture information. For example, the output of the light source is switched on or the shutter is opened so that the light is emitted.

  As described above, according to the present embodiment, it is possible to determine in real time whether or not the probe unit exists within a predetermined range based on the measurement location, and the measurement light is emitted from the probe unit only when necessary. Can be made. As a result, in the photoacoustic measurement using the probe unit, it is possible to reduce the possibility that the measurement light is emitted in an unintended direction.

  Furthermore, in this embodiment, the direction in which the measurement light is emitted can be limited by determining whether the posture information belongs within a predetermined range based on the measurement specific posture. It is possible to further reduce the possibility of being released into the water.

(Design changes)
It is also possible to combine the first embodiment and the second embodiment. In other words, by setting a non-emission specific space, determining whether or not there is a possibility of laser light being emitted into the non-emission specific space, and further determining whether the probe unit belongs to the position coordinates and orientation information, It is possible to further reduce the possibility that the measurement light is emitted in an unintended direction as compared with the case where the determination is made alone.

  The present invention is not limited to photoacoustic imaging but can be similarly applied to examination and diagnosis of a subject using a photoacoustic analysis method.

DESCRIPTION OF SYMBOLS 1 Light transmission part 2 Image generation part 3 Electroacoustic conversion part 3s Detection surface 4 System control part 5 Operation part 6 Display part 7 Subject 8a Avoidance determination part 8b Release determination part 10 Photoacoustic analyzer 11 Light source part 14 Waveguide part 15 Light irradiation unit 22 Reception unit 24 Scan control unit 25 Signal processing unit 70 Probe unit 81 Information acquisition unit 82 Magnetic sensor 83 Magnetic generation units 84a and 84b Determination unit 85 First information reception units 86a and 86b Second information reception unit 87 Estimator L Laser beam P1 Position coordinate P2 in probe unit space Position coordinate P3 in subject head space Position coordinate U of measurement location Photoacoustic wave

Claims (10)

A photoacoustic measurement device that irradiates measurement light into a subject, detects a photoacoustic wave generated in the subject, converts the photoacoustic wave into an electrical signal, and performs photoacoustic measurement based on the electrical signal In
A probe unit including a light irradiation unit for irradiating the measurement light and an electroacoustic conversion unit for converting the photoacoustic wave into an electrical signal;
Acquisition means for acquiring position coordinates and posture information in a space of the probe unit in real time, and acquiring position coordinates of a non-emission specific space which is a space where the measurement light is not desired to be emitted;
Estimating means for estimating the direction of the detection surface of the probe unit based on the posture information;
Based on the position coordinates of the probe unit, the direction in which the detection surface faces, and the position coordinates of the non-emission specific space, it is determined whether or not the measurement light may be emitted into the non-emission specific space. A judgment means to
An avoidance measure means for taking measures to avoid the situation where the measurement light is emitted into the non-emission specific space when the determination result that the possibility exists is obtained by the determination,
The determination means calculates an angle formed by a line connecting the position coordinates of the probe unit and the position coordinates of the non-emission specific space and a straight line extending in the direction from the position coordinates of the probe unit, A photoacoustic measuring device that judges that the possibility exists when the value is equal to or less than a predetermined threshold value . When the determination means determines that the possibility exists, the determination means further makes a stepwise determination according to the high possibility.
The photoacoustic measurement apparatus according to claim 1, wherein the avoidance measure means changes the content of the measure in accordance with the stepwise determination. The photoacoustic measurement apparatus according to claim 1 or 2 , wherein the acquisition unit acquires the position coordinates of the non-release specific space in real time. The photoacoustic measuring device according to claim 1 or 2 , wherein the acquisition means acquires the position coordinates of the non-release specific space registered in advance. The measurement is performed by the avoidance measure means when a distance between the position coordinates of the probe unit and the position coordinates of the non-emission specific space is a predetermined distance or more and the detection surface is in contact with an obstacle. If the light is deemed not released into space, photoacoustic measuring device according to 4 claim 1, characterized in that one which does not take the measures regardless the determination result by the determination unit . Using a probe unit having a light irradiating unit for irradiating measurement light and an electroacoustic converting unit for converting a photoacoustic wave into an electrical signal, the measuring light is irradiated into the subject and generated in the subject. In the photoacoustic measurement method of detecting the photoacoustic wave, converting the photoacoustic wave into an electrical signal, and performing photoacoustic measurement based on the electrical signal,
Obtaining position coordinates and posture information in space of the probe unit in real time ;
Obtaining position coordinates in a non-emission specific space, which is a space where the measurement light is not desired to be emitted ;
Estimating the direction of the detection surface of the probe unit based on the posture information ;
Based on the position coordinates of the probe unit, the direction in which the detection surface faces, and the position coordinates of the non-emission specific space, it is determined whether or not the measurement light may be emitted into the non-emission specific space. And steps to
A step of avoiding a situation in which the measurement light is emitted into the non-emission specific space when a determination result indicating that the possibility exists is obtained by the determination , and
In the determining step, an angle formed by a line connecting the position coordinates of the probe unit and the position coordinates of the non-emission specific space and a straight line extending in the direction from the position coordinates of the probe unit is calculated, A photoacoustic measurement method characterized by determining that the possibility exists when the angle is equal to or less than a predetermined threshold . In the step of determining, when it is determined that the possibility exists , a stepwise determination is further made in accordance with the high possibility.
The photoacoustic measurement method according to claim 6 , wherein in the step of taking the measure, the content of the measure is changed according to the stepwise determination. The photoacoustic measurement method according to claim 6 or 7 , wherein the position coordinates of the non-release specific space are acquired in real time. The photoacoustic measurement method according to claim 6 or 7 , wherein the position coordinates of the non-release specific space registered in advance are acquired. The measurement light is not emitted into the space because the distance between the position coordinates of the probe unit and the position coordinates of the non-emission specific space is a predetermined distance or more and the detection surface is in contact with an obstacle. 10. The photoacoustic measurement method according to claim 6, wherein the measure is not taken regardless of the determination result.

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