WO2017038906A1 - Dispositif imageur photo-acoustique - Google Patents

Dispositif imageur photo-acoustique Download PDF

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Publication number
WO2017038906A1
WO2017038906A1 PCT/JP2016/075582 JP2016075582W WO2017038906A1 WO 2017038906 A1 WO2017038906 A1 WO 2017038906A1 JP 2016075582 W JP2016075582 W JP 2016075582W WO 2017038906 A1 WO2017038906 A1 WO 2017038906A1
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light source
unit
frequency
absolute value
photoacoustic imaging
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PCT/JP2016/075582
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English (en)
Japanese (ja)
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中塚　均
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プレキシオン株式会社
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Publication of WO2017038906A1 publication Critical patent/WO2017038906A1/fr

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    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B8/00—Diagnosis using ultrasonic, sonic or infrasonic waves
    • A61B8/13—Tomography

Definitions

  • the present invention relates to a photoacoustic imaging apparatus, and more particularly, to a photoacoustic imaging apparatus including a light source driving unit that controls pulsed light from a light source unit based on a detection frequency band of a detection unit.
  • a photoacoustic imaging apparatus including a light source driving unit that controls pulsed light from a light source unit based on a detection frequency band of a detection unit is known (for example, see Patent Document 1).
  • Patent Document 1 discloses a photoacoustic imaging apparatus including a light source unit. This photoacoustic imaging apparatus is provided with an ultrasonic probe and an imaging unit.
  • the light source unit includes a Q-switch pulse laser light source.
  • the photoacoustic imaging apparatus is configured to irradiate a subject with laser light by a light source unit and detect an acoustic wave signal generated from the subject by an ultrasonic probe.
  • the imaging unit is configured to image the acoustic wave signal detected by the ultrasonic probe.
  • the photoacoustic imaging apparatus is configured to adjust the pulse width of the pulsed light from the Q-switch pulse laser light source in accordance with the frequency band of the ultrasonic probe.
  • the photoacoustic imaging apparatus of Patent Document 1 is configured to adjust the pulse width of the pulsed light from the light source in accordance with the frequency band of the ultrasonic probe.
  • the frequency characteristic of the detected acoustic wave is controlled so as to match the frequency band of the ultrasonic probe only by controlling the pulse width of the pulsed light. The problem is that it is difficult.
  • the present invention has been made to solve the above-described problems, and one object of the present invention is to provide a detection unit (ultrasonic probe) by a method other than the method for controlling the pulse width of pulsed light.
  • the photoacoustic imaging apparatus is capable of controlling the frequency characteristics of the detected acoustic wave so as to be adapted to the frequency band.
  • a light source unit In the photoacoustic imaging apparatus according to one aspect of the present invention, a light source unit, a detection unit that detects an acoustic wave generated from the inside of the subject due to light being irradiated on the subject by the light source unit, and a light source A light source driving unit that drives the light source unit by supplying power to the unit, and the light source driving unit is configured to start rising of a pulse waveform of light emitted from the light source unit based on a detection frequency (frequency band) of the detection unit.
  • the ratio between the inclination and the falling inclination is set, and the absolute value of the inclination ratio is increased as the detection frequency range of the detection unit is wider.
  • the frequency range (frequency characteristics) of the detected acoustic wave can be expanded by increasing the absolute value of the ratio of the slopes of the pulse waveforms. According to the configuration of the present invention, even when the detection frequency range of the detection unit is wide, it is possible to adapt the frequency range of the acoustic wave and the detection frequency of the detection unit by increasing the absolute value of the slope of the pulse waveform. Therefore, the frequency characteristic of the detected acoustic wave can be controlled by a method other than the method of controlling the pulse width of the pulsed light so as to be adapted to the frequency band of the detection unit.
  • the light source driving unit is configured such that one of the absolute value of the rising slope or the absolute value of the falling slope is 1.5 times or more and 10 times or less of the other. It is comprised so that it may become. If comprised in this way, the frequency range of the detected acoustic wave is made by making one of the absolute value of the rising slope or the absolute value of the falling slope 1.5 times or more and 10 times or less of the other. Since it can be easily expanded, the frequency characteristic of the detected acoustic wave can be easily controlled so as to be adapted to the frequency band of the detector by a method other than the method of controlling the pulse width of the pulsed light.
  • the light source driving unit is preferably configured such that the half width of the pulse waveform is 12.5 nsec or more and 500 nsec or less.
  • the pulse width is too narrow, less than 12.5 nsec, even if the absolute value of the slope ratio is increased, only the wide band that does not affect reception spreads and the peak frequency decreases. If the pulse width exceeds 500 nsec and is too wide, the amplitude of the peak frequency becomes small. Therefore, if the half width of the pulse waveform is set to 12.5 nsec or more and 500 nsec or less, the amplitude of the peak frequency can be ensured, so that the acoustic wave from the subject can be detected efficiently.
  • the half width of the pulse waveform is 50 nsec or more and 200 nsec or less.
  • the amplitude of the peak frequency can be ensured more reliably by setting the half width of the pulse waveform to 50 nsec or more and 200 nsec or less, so that the acoustic wave from the subject can be detected more efficiently. Can do.
  • the light source driving unit is preferably configured such that the absolute value of the falling slope is larger than the absolute value of the rising slope.
  • the response characteristic of the light emitting element for example, LED
  • the absolute value of the slope of the falling edge of the pulse waveform can be increased, so that the frequency characteristics of the detected acoustic wave can be easily adapted to the frequency band of the detection unit. Can be controlled.
  • the photoacoustic imaging apparatus is preferably configured such that the light source driving unit sets the pulse width to be smaller as the maximum frequency of the acoustic wave that can be detected by the detection unit is larger.
  • the acoustic wave generated from the subject is generated as an acoustic wave having a frequency equal to or lower than the maximum frequency with a frequency having a reciprocal value of the pulse width irradiated to the subject as a maximum frequency.
  • the light source driving unit is configured to set the pulse width to be smaller as the maximum frequency of the acoustic wave that can be detected by the detection unit is larger.
  • the maximum frequency of the acoustic wave generated from the subject can be increased as the maximum frequency is increased.
  • the maximum frequency is the maximum frequency among the frequencies that are -6 dB relative to the peak value (0 dB) of the frequency component of the acoustic wave that can be detected by the detection unit. It is described as a frequency.
  • the maximum frequency that can be detected by the detection unit is preferably 1 MHz or more and 20 MHz or less.
  • the detection frequency of the detection unit is higher than 20 MHz, the ultrasonic wave is attenuated, so that the depth becomes shallow and only the surface layer of the subject can be observed.
  • the detection frequency is lower than 1 MHz, the resolution becomes worse while the depth becomes deeper. Therefore, if the maximum frequency that can be detected by the detection unit is configured to be 1 MHz or more and 20 MHz or less, each of the depth and the resolution can be ensured.
  • the light source driving unit is preferably configured such that the pulse waveform of the light emitted from the light source unit is either a triangular shape or a trapezoidal shape.
  • the pulse waveform of the light emitted from the light source unit has either a triangular shape or a trapezoidal shape, so that the rising slope and falling slope of the pulse waveform can be easily controlled. .
  • the light source unit is preferably configured to include a semiconductor light emitting element. If configured in this way, unlike the case of using a solid-state laser element (Q-switch pulse laser light source), an optical surface plate and a strong housing for suppressing characteristic fluctuation due to vibration of the optical system are not required. Therefore, the structure of the photoacoustic imaging apparatus can be prevented from increasing in size.
  • a semiconductor light emitting element Q-switch pulse laser light source
  • a photoacoustic imaging apparatus capable of controlling characteristics can be provided.
  • FIG. 1 is a block diagram showing an overall configuration of a photoacoustic imaging apparatus according to first to third embodiments of the present invention.
  • FIG. FIG. 3 is a block diagram showing a configuration relating to irradiation of pulsed light in the photoacoustic imaging apparatus according to the first to third embodiments of the present invention.
  • FIG. 6 is a diagram for explaining the characteristics of the detection frequency of the detection unit according to the first to third embodiments of the present invention.
  • FIG. 5 is a diagram for explaining the relationship between a pulse waveform having a ratio of absolute values of inclinations of 1 to 3 times and a frequency response of an acoustic wave detected in each of the photoacoustic imaging apparatus according to the first embodiment of the present invention. .
  • FIG. 10 is a diagram when the pulse waveform of the photoacoustic imaging apparatus according to the modification of the first to third embodiments of the present invention is trapezoidal.
  • the photoacoustic imaging apparatus 100 detects an acoustic wave A from a detection target (blood, organ, puncture needle, etc.) inside a subject P (human body, etc.), and photoacoustic It has a function of imaging a wave signal.
  • a detection target blood, organ, puncture needle, etc.
  • a subject P human body, etc.
  • the photoacoustic imaging apparatus 100 is provided with a probe main body 1 and an apparatus main body 2 as shown in FIG.
  • the photoacoustic imaging apparatus 100 is provided with a cable 3 for connecting the probe main body 1 and the apparatus main body 2.
  • the probe main body 1 is configured to be disposed on the surface of the subject P (such as a human body surface) while being held by an operator.
  • the probe main body 1 is provided with a light source 11 and a detector 12.
  • the light source unit 11 is configured to be able to irradiate the subject P with light.
  • the detection unit 12 is configured to detect an acoustic wave A generated from within the subject P due to the light being irradiated to the subject P by the light source unit 11.
  • the detection unit 12 is configured to transmit the acoustic wave A as a photoacoustic wave signal to the apparatus main body unit 2 via the cable 3.
  • the apparatus main body 2 is provided with a light source driving unit 21, a control unit 22, an imaging unit 23, an image display unit 24, and an operation unit 25.
  • the light source drive unit 21 is configured to drive the light source unit 11 by supplying power to the light source unit 11 based on a command from the control unit 22.
  • the control unit 22 is configured to control each unit of the photoacoustic imaging apparatus 100.
  • the imaging unit 23 is configured to process and image the photoacoustic wave signal detected by the probe main body unit 1.
  • the image display unit 24 includes, for example, a liquid crystal monitor and is configured to display an imaged photoacoustic wave signal.
  • the operation unit 25 includes, for example, a keyboard and is configured to accept an input operation from the operator.
  • the light source part 11 contains the some LED element 11a.
  • the LED element 11a is configured, for example, as a plurality of light emitting element groups 11b in which a plurality (n) of LED elements 11a are connected in series with each other. Three rows are connected in parallel.
  • the LED element 11a is an example of the “semiconductor light emitting element” in the claims.
  • the light source unit 11 emits pulsed light having an infrared wavelength (for example, a wavelength of 600 nm to 1000 nm, preferably a wavelength of about 850 nm) when power is supplied from the light source driving unit 21. It is configured to be possible.
  • the light source unit 11 is configured to irradiate the subject P with light emitted from the plurality of LED elements 11a.
  • the pulsed light irradiated to the subject P from the light source part 11 is absorbed by the detection target object (for example, hemoglobin etc.) in the subject P.
  • the detection target object expands and contracts (returns from the expanded size to the original size) according to the irradiation intensity (light quantity and absorption amount) of the pulsed light, thereby detecting the detection target object (subject P).
  • the detection target object expands and contracts (returns from the expanded size to the original size) according to the irradiation intensity (light quantity and absorption amount) of the pulsed light, thereby detecting the detection target object (subject P).
  • the control unit 22 is configured to transmit a light trigger signal to the light source driving unit 21.
  • the light source drive part 21 is comprised so that light may be irradiated from the light source part 11 according to a light trigger signal.
  • the control unit 22 is configured to transmit a sampling trigger signal synchronized with the light trigger signal to the imaging unit 23.
  • the light source drive unit 21 includes a drive power supply unit 21a and switch units 21b to 21d.
  • the drive power supply unit 21a is composed of, for example, a DC / DC converter or the like, and is configured to acquire power from an external power supply (not shown) and to acquire a control signal from the control unit 22. And the drive power supply part 21a is comprised so that the acquired electric power may be converted into the direct-current electric power which has the voltage value V according to the acquired control signal.
  • the drive power supply unit 21a is connected to the anode side of the light emitting element group 11b of the light source unit 11, and is configured to supply generated power (apply a voltage value V) to the anode side of the LED element 11a. ing.
  • Each one side of the switch units 21b to 21d is connected to the cathode side of the LED element 11a of the light source unit 11, and the other side is grounded.
  • the switch units 21b to 21d include, for example, an FET (Field Effect Transistor), and are configured to be able to be switched on and off based on a pulsed light trigger signal from the control unit 22, respectively.
  • the voltage value on the cathode side of the LED element 11a decreases (is grounded), so that a potential difference (substantially voltage value) occurs between the anode side and the cathode side of the LED element 11a. V) is generated, and the current flows through the LED element 11a. That is, the magnitude of the current value flowing through the LED element 11a is emitted from the light source unit 11 in accordance with the magnitude of the pulse width tw of the pulsed light emitted from the light source unit 11 when the switch units 21b-21d are turned on. This corresponds to the amount of pulsed light.
  • the detection unit 12 is configured by a piezoelectric element (for example, lead zirconate titanate (PZT)). And the detection part 12 is comprised so that it may vibrate and produce a voltage (signal), when the above-mentioned acoustic wave A is acquired. And the detection part 12 is comprised so that a photoacoustic wave signal may be transmitted to the apparatus main body part 2, as shown in FIG.
  • a piezoelectric element for example, lead zirconate titanate (PZT)
  • PZT lead zirconate titanate
  • the maximum frequency fmax that can be detected by the detection unit 12 is determined from the frequency characteristic (detection frequency characteristic) of the acoustic wave A that can be detected by the detection unit 12.
  • the higher frequency is 7.5 MHz.
  • the maximum frequency fmax is a frequency having a value of ⁇ 6 dB with respect to the peak value (0 dB) of the frequency component of the acoustic wave A that can be detected by the detection unit 12.
  • a large frequency is described as the maximum frequency fmax.
  • the detection unit 12 is configured such that the maximum frequency fmax that can be detected is 20 MHz or less.
  • the resolution increases, while the attenuation rate when the acoustic wave A propagates inside the subject P increases.
  • the acoustic wave A greater than 20 MHz is generated from the subject P (for example, a living body)
  • the acoustic wave A greater than 20 MHz generated from a portion deeper than the surface layer portion may reach the detection unit 12. It becomes difficult.
  • the maximum frequency fmax that can be detected by the detection unit 12 is greater than 20 MHz, the sound that is substantially detected when the maximum frequency fmax that can be detected by the detection unit 12 is 20 MHz.
  • the frequency of the wave A is equivalent. Therefore, it is preferable to configure the detection unit 12 so that the maximum frequency fmax of the detection unit 12 is 20 MHz or less.
  • the maximum frequency fmax that can be detected by the detection unit 12 is configured to be 1 MHz or more.
  • the smaller the frequency of the acoustic wave A the greater the distance (depth) that the acoustic wave A can propagate through the subject P, but the smaller the resolution.
  • the resolution is about 1.5 mm.
  • the resolution is 1.5 mm or less. Therefore, by configuring the detection unit 12 so that the maximum frequency fmax is 1 MHz or more, it is possible to suppress difficulty in diagnosis using the photoacoustic imaging apparatus 100.
  • the light source driving unit 21 is configured such that the pulse waveform of the light emitted from the light source unit 11 has either a triangular shape or a trapezoidal shape. Specifically, as shown in the graphs of pulse waveforms in FIGS. 4 to 6, after the pulse waveform rises with a linear gradient and the light intensity becomes maximum, it falls with a linear gradient. That is, the pulse waveform has a triangular shape.
  • the light source driving unit 21 sets the ratio between the rising slope and the falling slope of the pulse waveform of the light emitted from the light source unit 11 based on the detection frequency of the detection unit 12. It is configured as follows. In addition, the absolute value of the ratio of the inclination is increased as the detection frequency range of the detection unit 12 is wider. Specifically, as shown in FIG. 2, the slope of the pulse waveform is controlled by controlling the gate voltage of the FETs of the switch sections 21b to 21d. That is, when the gate voltage is sharply raised, the switch portions 21b to 21d are quickly turned on, so that the rising slope of the pulse waveform is increased.
  • FIG. 4 respectively show the pulse waveform and sound when the absolute value of the falling slope is 1, 2, 3 and 1.5 times the absolute value of the rising slope.
  • 2 is a graph of the frequency response of a wave A. As shown in the frequency response graphs of FIGS.
  • the slope of the increase (decrease) in the light intensity between the time of 10% plus (Imin + 0.1 ⁇ ⁇ I) and the time of 90% plus (Imin + 0.9 ⁇ ⁇ I) is there.
  • 5A and 5B are graphs of the pulse waveform and the frequency response of the acoustic wave A when the absolute value of the rising slope is twice and three times the absolute value of the falling slope, respectively. is there. Since there is no significant difference between FIG. 4B and FIG. 5A and between FIG. 4C and FIG. 5B, the rise of the pulse waveform Substantially equivalent frequency response characteristics can be obtained even if the relationship between the slope and the slope of the fall is reversed.
  • one of the absolute value of the rising slope or the falling slope of the pulse waveform is configured to be 1.5 times to 10 times the other.
  • the peak frequency The frequency range is expanded by increasing the intensity of the acoustic wave A at the above frequencies.
  • 6A and 6B are graphs of the pulse waveform and the frequency response when the absolute value of the falling slope of the pulse waveform is 10 times and 20 times the absolute value of the rising slope, respectively. It is. As shown in the frequency response graphs of FIGS.
  • the ratio between the absolute value of the falling slope and the absolute value of the rising slope of the pulse waveform was increased from 10 times to 20 times. However, there is no significant effect on the frequency response characteristics. Based on these results, it is desirable that one of the absolute value of the rising slope or the falling slope of the pulse waveform be 1.5 to 10 times the other.
  • the light source driving unit 21 is configured such that the absolute value of the falling slope is larger than the absolute value of the rising slope.
  • the absolute value of the falling slope is the absolute value of the rising slope, respectively. They are 2 times, 3 times, 1.5 times, 10 times, and 20 times, and the slope of falling is larger.
  • the light source unit 11 and the detection unit 12 that detects the acoustic wave A generated from within the subject P due to the light being irradiated on the subject P by the light source unit 11.
  • a light source drive unit 21 that supplies power to the light source unit 11 to drive the light source unit 11.
  • the light source drive unit 21 is irradiated from the light source unit 11 based on the detection frequency (frequency band) of the detection unit 12.
  • the ratio between the rising slope and the falling slope of the pulse waveform of the light to be set is set, and the absolute value of the slope ratio is increased as the detection frequency range of the detector 12 is wider.
  • the frequency range of the acoustic wave A and the detection frequency of the detection unit 12 can be adapted by increasing the absolute value of the slope of the pulse waveform.
  • the frequency characteristic of the detected acoustic wave A can be controlled by a method other than the method of controlling the pulse width tw of the pulsed light so as to be adapted to the frequency band of the detection unit 12.
  • the light source driving unit 21 is configured such that one of the absolute value of the rising slope or the absolute value of the falling slope is 1.5 to 10 times the other. Configure as follows. Accordingly, the frequency range of the detected acoustic wave A can be easily expanded by setting one of the absolute value of the rising slope and the absolute value of the falling slope to 1.5 times to 10 times the other. Therefore, the frequency characteristic of the detected acoustic wave A can be easily controlled by a method other than the method of controlling the pulse width tw of the pulsed light so as to easily match the frequency band of the detection unit 12.
  • the light source driving unit 21 is configured such that the absolute value of the falling slope is larger than the absolute value of the rising slope.
  • the response characteristic of the light emitting element for example, LED
  • the absolute value of the slope of the falling edge of the pulse waveform can be increased, so that the frequency characteristics of the detected acoustic wave A can be easily controlled to match the frequency band of the detection unit 12. .
  • the maximum frequency fmax that can be detected by the detection unit 12 is 1 MHz or more and 20 MHz or less.
  • the detection frequency of the detection unit 12 increases, the ultrasonic wave attenuates, so that the depth becomes shallower, and only the surface layer of the subject P can be observed. Further, when the detection frequency is lowered, the depth is increased while the resolution is deteriorated. Therefore, if the maximum frequency fmax that can be detected by the detection unit 12 is configured to be 1 MHz or more and 20 MHz or less, each of the depth and the resolution can be ensured.
  • the light source driving unit 21 is configured such that the pulse waveform of the light emitted from the light source unit 11 has either a triangular shape or a trapezoidal shape. Since the pulse waveform of the light emitted from the light source unit 11 is either triangular or trapezoidal, the rising slope and falling slope of the pulse waveform can be easily controlled.
  • the light source unit 11 is configured to include the semiconductor light emitting element.
  • the semiconductor light emitting element Q-switched pulse laser light source
  • an optical surface plate and a strong housing for suppressing characteristic fluctuations due to vibration of the optical system are not required.
  • An increase in the size of the imaging apparatus 100 can be suppressed.
  • the apparatus main body unit 22 includes a light source driving unit 221, a control unit 222, an imaging unit 23, an image display unit 24, and an operation unit 25.
  • the light source driving unit 221 is configured to drive the light source unit 11 by supplying power to the light source unit 11 based on a command from the control unit 222.
  • the control unit 222 is configured to control each unit of the photoacoustic imaging apparatus 200.
  • the half width of the pulse waveform is configured to be 12.5 nsec or more and 500 nsec or less.
  • the photoacoustic imaging apparatus 200 controls the time during which the switch units 21b to 21d are turned on based on the light trigger signal from the control unit 222, thereby generating a pulse waveform.
  • the full width at half maximum is configured to be 12.5 nsec or more and 500 nsec or less.
  • FIG. 7 is a pulse waveform in which the half width is 12.5 nsec and the absolute value of the falling slope is one time the absolute value of the rising slope.
  • FIG. 7B shows a pulse waveform in which the half width of the pulse waveform is 12.5 nsec and the absolute value of the falling slope is four times the absolute value of the rising slope.
  • FIG. 8 is a pulse waveform in which the half-value width of the pulse waveform is 500 nsec and the absolute value of the falling slope is one time the absolute value of the rising slope.
  • FIG. 8B shows a pulse waveform in which the half width of the pulse waveform is 500 nsec and the absolute value of the falling slope is four times the absolute value of the rising slope.
  • the frequency range of the acoustic wave A is expanded by increasing the absolute value of the ratio of the slopes.
  • the amplitude of the peak frequency is reduced by increasing the half width.
  • the half width of the pulse waveform is 12.5 nsec or more and 500 nsec or less.
  • the light source driving unit 221 is configured to set the half width of the pulse waveform to be smaller as the maximum frequency fmax of the acoustic wave A that can be detected by the detection unit 12 is larger. . Specifically, as shown in FIGS. 7 and 8, the frequency range is wider in FIG. 7 where the half width of the pulse waveform is smaller.
  • the light source driving unit 221 is configured such that the half width of the pulse waveform is 12.5 nsec or more and 500 nsec or less.
  • the pulse width tw is too narrow, even if the absolute value of the slope ratio is increased, only the wide band that does not affect reception spreads and the peak frequency decreases. Further, if the pulse width tw is too wide, the amplitude of the peak frequency becomes small.
  • the half-width of the pulse waveform is configured to be 12.5 nsec or more and 500 nsec or less, the amplitude of the peak frequency can be secured, so that the acoustic wave A from the subject P can be detected efficiently. it can.
  • the light source drive unit 221 is configured to set the pulse width tw to be smaller as the maximum frequency fmax of the acoustic wave A that can be detected by the detection unit 12 is larger.
  • the acoustic wave A generated from the subject P is generated as an acoustic wave A having a frequency equal to or lower than the maximum frequency fmax, with the frequency having a reciprocal value of the pulse width tw irradiated to the subject P being the maximum frequency fmax.
  • the light source driving unit 221 is configured to set the pulse width tw to be smaller as the maximum frequency fmax of the acoustic wave A that can be detected by the detection unit 12 is larger.
  • the maximum frequency fmax of the acoustic wave A generated from the subject P can be increased as the maximum frequency fmax of 12 is increased.
  • the maximum frequency fmax of the acoustic wave A that can be detected by the detection unit 12 and the maximum frequency fmax of the acoustic wave A generated from the subject P can be substantially matched. A can be generated.
  • the apparatus main body unit 32 is provided with a light source driving unit 321, a control unit 322, an imaging unit 23, an image display unit 24, and an operation unit 25.
  • the light source driving unit 321 is configured to drive the light source unit 11 by supplying power to the light source unit 11 based on a command from the control unit 322.
  • the control unit 322 is configured to control each unit of the photoacoustic imaging apparatus 300.
  • the half width of the pulse waveform is configured to be not less than 50 nsec and not more than 200 nsec.
  • the photoacoustic imaging apparatus 300 controls the time during which the switch units 21b to 21d are turned on based on the light trigger signal from the control unit 322, thereby generating a pulse waveform.
  • the half width is configured to be 50 nsec or more and 200 nsec or less.
  • FIG. 9 shows a pulse waveform in which the half-value width is 50 nsec and the absolute value of the falling slope is one time the absolute value of the rising slope.
  • FIG. 9B shows a pulse waveform in which the half width is 50 nsec and the absolute value of the falling slope is four times the absolute value of the rising slope.
  • FIG. 10A shows a pulse waveform in which the half-value width is 200 nsec and the absolute value of the falling slope is one time the absolute value of the rising slope.
  • FIG. 10B shows a pulse waveform in which the half width is 200 nsec and the absolute value of the falling slope is four times the absolute value of the rising slope.
  • the frequency range is expanded by increasing the absolute value of the ratio of the slopes.
  • a decrease in the amplitude of the peak frequency is suppressed as compared with FIG. From these results, it is more preferable that the half width of the pulse waveform is 50 nsec or more and 200 nsec or less.
  • the other configuration of the photoacoustic imaging apparatus 300 according to the third embodiment is the same as that of the photoacoustic imaging apparatus 100 according to the first embodiment.
  • the half width of the pulse waveform is configured to be not less than 50 nsec and not more than 200 nsec.
  • the half-value width of the pulse waveform is set to 50 nsec or more and 200 nsec or less, the amplitude of the peak frequency can be more reliably ensured, so that the acoustic wave A from the subject P can be detected more efficiently.
  • the present invention is not limited to this.
  • a semiconductor laser may be used.
  • the pulse waveform of the pulsed light has a triangular shape
  • the pulse waveform may be trapezoidal as shown in FIG.
  • FIG. 11 is a graph in which the absolute value of the rising slope of the pulse waveform is twice and three times the absolute value of the falling slope.
  • the absolute value of the falling slope of the pulse waveform is larger than the absolute value of the rising slope.
  • the present invention is not limited to this.
  • the absolute value of the rising slope of the pulse waveform may be larger than the absolute value of the falling slope.
  • the example in which the on / off of the switch unit is controlled is shown as a method for controlling the slope of the pulse waveform of the pulsed light.
  • the present invention is not limited to this.
  • the slope of the pulse waveform of the pulsed light may be controlled by controlling the voltage from the drive power supply unit (control unit).
  • the example in which the light source driving unit is provided in the apparatus main body has been described.
  • the present invention is not limited to this.
  • the light source driving unit may be provided in the probe main body.
  • LED element 11a (light emitting element) 12 detectors 21, 221, 321 light source driver 100, 200, 300 photoacoustic imaging device

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Abstract

La présente invention inclut : une unité de source de lumière (11) ; une unité de détection (12) qui détecte des ondes acoustiques (A) générées depuis l'intérieur d'un sujet (P) en raison de l'irradiation du sujet (P) par de la lumière de l'unité de source de lumière (11) ; et une unité de pilotage (21) de source de lumière qui alimente en puissance l'unité de source de lumière (11) et qui pilote l'unité de source de lumière (11). L'unité de pilotage (21) de source de lumière sert à établir un ratio entre une pente montante et une pente descendante d'une forme d'onde à impulsions de la lumière émise par l'unité de source de lumière (11) sur la base de la fréquence détectée (largeur de bande de fréquence) par l'unité de détection (12), et est configurée de sorte que plus la plage de la fréquence détectée par l'unité de détection (12) est large, plus la valeur absolue du ratio des pentes est élevée.
PCT/JP2016/075582 2015-08-31 2016-08-31 Dispositif imageur photo-acoustique WO2017038906A1 (fr)

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