WO2019044212A1 - Dispositif de génération d'images photoacoustiques et procédé d'acquisition d'images - Google Patents

Dispositif de génération d'images photoacoustiques et procédé d'acquisition d'images Download PDF

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Publication number
WO2019044212A1
WO2019044212A1 PCT/JP2018/026597 JP2018026597W WO2019044212A1 WO 2019044212 A1 WO2019044212 A1 WO 2019044212A1 JP 2018026597 W JP2018026597 W JP 2018026597W WO 2019044212 A1 WO2019044212 A1 WO 2019044212A1
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Prior art keywords
photoacoustic
excitation light
image
photoacoustic image
light generation
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PCT/JP2018/026597
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English (en)
Japanese (ja)
Inventor
温之 橋本
山本　勝也
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富士フイルム株式会社
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Publication of WO2019044212A1 publication Critical patent/WO2019044212A1/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 photoacoustic wave generation unit disposed at the tip of the insert inserted in the subject detects the photoacoustic wave generated by receiving the excitation light emitted from the light source by the acoustic wave detection means.
  • the present invention relates to a photoacoustic image generation device that generates a photoacoustic image based on a signal obtained by the above-described method, and an image acquisition method in the photoacoustic image generation device.
  • Ultrasonography is known as a type of imaging that can noninvasively inspect the internal condition of a living body.
  • an ultrasonic probe capable of transmitting and receiving ultrasonic waves is used.
  • the ultrasonic waves travel inside the living body and are reflected at the tissue interface.
  • the internal appearance can be imaged by receiving the reflected ultrasound by the ultrasound probe and calculating the distance based on the time until the reflected ultrasound returns to the ultrasound probe.
  • photoacoustic imaging which image-forms the inside of a biological body using a photoacoustic effect is known.
  • pulsed laser light is applied to the inside of a living body.
  • living tissue absorbs the energy of the pulsed laser light, and adiabatic expansion by the energy generates an ultrasonic wave (photoacoustic wave).
  • ultrasonic wave photoacoustic wave
  • Visualization of the inside of the living body based on the photoacoustic wave is possible by detecting the photoacoustic wave with an ultrasonic probe or the like and constructing a photoacoustic image based on the detection signal.
  • a puncture needle in which a photoacoustic wave generating unit for absorbing light and generating a photoacoustic wave is provided in the vicinity of the tip.
  • a photoacoustic wave generating unit for absorbing light and generating a photoacoustic wave is provided in the vicinity of the tip.
  • an optical fiber is provided up to the tip of the puncture needle, and the light guided by the optical fiber is irradiated to the photoacoustic wave generation unit.
  • the photoacoustic wave generated in the photoacoustic wave generation unit is detected by the ultrasonic probe, and a photoacoustic image is generated based on the detection signal.
  • a portion of the photoacoustic wave generation unit appears as a bright spot, and the position of the puncture needle can be confirmed using the photoacoustic image.
  • one image may be configured using a plurality of photoacoustic images, or one line may be used using reception data of a plurality of waves. In this case, there is a problem that the frame rate decreases.
  • the photoacoustic wave can be efficiently received by the ultrasonic probe by optimizing the pulse width of the excitation light for generating the photoacoustic wave according to the ultrasonic probe. Is disclosed. However, in the method of Patent Document 1, efficiency improvement is insufficient such that many acoustic waves of frequency components that do not contribute to imaging still occur.
  • Patent Document 2 discloses that the photoacoustic wave can be efficiently received by the ultrasonic probe by determining the pulse width and the number of pulses of the excitation light according to the reception frequency characteristic of the ultrasonic probe. ing. Further, in Patent Document 2, after the pulse width and the number of pulses of excitation light are determined according to the reception frequency characteristic of the ultrasonic probe, the resolution can be improved by changing the pulse repetition period while keeping the pulse width constant. It is stated that it can. However, if the pulse repetition period is changed after determining the pulse width of the excitation light, the band of the generated photoacoustic wave changes, and the reception frequency characteristic of the ultrasonic probe does not match, and the reception efficiency of the ultrasonic probe becomes There is a problem of falling.
  • the present invention in view of the above circumstances, in photoacoustic imaging using an insert provided with a photoacoustic wave generation unit in the vicinity of the tip, a photoacoustic image generation device with improved visible depth in a photoacoustic image, and light
  • An object of the present invention is to provide an image acquisition method in an acoustic image generation device.
  • the photoacoustic wave generation unit disposed at the tip of the insert inserted in the subject receives the excitation light emitted from the light source and the photoacoustic wave is generated.
  • a photoacoustic image generation apparatus including a photoacoustic image generation unit that generates a photoacoustic image based on a signal obtained by detection by an acoustic wave detection unit, a light source is based on a reception frequency characteristic of the acoustic wave detection unit.
  • a control unit that performs control to adjust the excitation light generation condition based on the pulse width of the excitation light generated in the light source and the number of pulses.
  • control unit adjusts the excitation light generation condition to approximate the frequency characteristic of the photoacoustic wave detected by the acoustic wave detection unit and the reception frequency characteristic of the acoustic wave detection unit. Control may be performed.
  • control unit stores a plurality of excitation light generation conditions having different frequency characteristics of the photoacoustic wave generated in the object, and the excitation light generation condition selected from among the plurality of stored excitation light generation conditions
  • the light source may be controlled based on
  • control unit stores a plurality of excitation light generation conditions for each type of acoustic wave detection means having different reception frequency characteristics, and the excitation light selected by the user from among the plurality of stored excitation light generation conditions
  • the light source may be controlled based on the generation condition.
  • control unit may adjust the excitation light generation condition based on the position of the distal end portion of the insert in the photoacoustic image.
  • the control unit may adjust the excitation light generation condition based on the image depth of the photoacoustic image.
  • control unit may adjust the excitation light generation condition based on the focal depth of the photoacoustic image.
  • the photoacoustic image generation unit may perform correction processing on the photoacoustic image based on the excitation light generation condition.
  • the photoacoustic wave generated when the photoacoustic wave generation unit disposed at the tip of the insert inserted into the subject receives the excitation light emitted from the light source is an acoustic wave. It is an image acquisition method in a photoacoustic image generation apparatus provided with the photoacoustic image generation part which produces a photoacoustic image based on the signal obtained by detecting by detection means, and the light source receives the acoustic wave detection means Based on the frequency characteristics, control is performed to adjust the excitation light generation conditions based on the pulse width of the excitation light generated in the light source and the number of pulses.
  • the excitation light generation condition is adjusted to perform control to make the frequency characteristic of the photoacoustic wave detected by the acoustic wave detection means closer to the reception frequency characteristic of the acoustic wave detection means.
  • a plurality of excitation light generation conditions having different frequency characteristics of the photoacoustic wave generated in the object are stored, and the light source is selected based on the excitation light generation conditions selected from among the plurality of stored excitation light generation conditions. May be controlled.
  • a plurality of excitation light generation conditions are stored for each type of reception frequency characteristics of the acoustic wave detection means different, and based on the excitation light generation conditions selected by the user from among the plurality of stored excitation light generation conditions.
  • the light source may be controlled.
  • the excitation light generation condition may be adjusted based on the position of the distal end portion of the insert in the photoacoustic image.
  • the excitation light generation condition may be adjusted based on the image depth of the photoacoustic image.
  • the excitation light generation condition may be adjusted based on the focal depth of the photoacoustic image.
  • correction process may be performed on the photoacoustic image based on the excitation light generation condition.
  • the reception frequency characteristics of the acoustic wave detecting means with respect to the light source in the photoacoustic imaging using the insert provided with the photoacoustic wave generating unit near the tip Since the control for adjusting the excitation light generation condition based on the pulse width of the excitation light generated in the light source and the plurality of pulses is performed based on the above, the reception efficiency of the photoacoustic wave in the acoustic wave detection means As a result, the visible depth in the photoacoustic image can be improved.
  • a block diagram showing a schematic configuration of a photoacoustic image generation apparatus according to a first embodiment of the present invention
  • Cross-sectional view showing the configuration of the tip portion of the puncture needle Graph showing the waveform of excitation light Graph showing the photoacoustic wave waveform Graph showing spectrum of photoacoustic wave Graph showing the photoacoustic wave waveform Graph showing the waveform of excitation light Graph showing spectrum of photoacoustic wave Graph showing the waveform of excitation light Graph showing spectrum of photoacoustic wave Graph showing the waveform of excitation light Graph showing spectrum of photoacoustic wave Graph showing the waveform of excitation light Graph showing spectrum of photoacoustic wave Graph showing spectrum of photoacoustic wave Graph showing spectrum of photoacoustic wave Graph showing spectrum of photoacoustic wave Graph showing spectrum of photoacoustic wave Graph showing spectrum of photoacoustic wave Graph showing spectrum of photoacoustic wave Graph showing spectrum of photoacoustic wave
  • FIG. 1 is a schematic view showing an overall configuration of a photoacoustic image generation apparatus 10 according to a first embodiment of the present invention.
  • the shape of the ultrasonic probe (hereinafter simply referred to as a probe) 11 is schematically shown.
  • the photoacoustic image generating apparatus 10 includes a probe 11 (corresponding to an acoustic wave detecting unit according to the present invention), an ultrasonic unit 12, a laser unit 13, and a puncture needle 15 (the present invention). Equivalent to the insert of The puncture needle 15 and the laser unit 13 are connected by an optical fiber 15 b.
  • the puncture needle 15 is detachable from the laser unit 13 and is configured to be disposable.
  • an ultrasonic wave is used as the acoustic wave, but the invention is not limited to the ultrasonic wave, and if an appropriate frequency is selected in accordance with an object to be detected, measurement conditions, etc. Acoustic waves may be used.
  • the laser unit 13 is provided with a solid-state laser light source using, for example, YAG (yttrium aluminum garnet) and alexandrite.
  • the laser light emitted from the solid state laser light source of the laser unit 13 is guided by the optical fiber 15 b and is incident on the puncture needle 15.
  • the laser unit 13 of the present embodiment emits pulsed laser light in the near infrared wavelength range.
  • the near infrared wavelength range means and a wavelength range of 700 nm (nanometers) to 850 nm (nanometers).
  • the solid-state laser light source is used, but another laser light source such as a gas laser light source may be used, or a light source other than the laser light source may be used.
  • the laser unit 13 can also be configured using a LD (Laser Diode) or an LED (Light Emitting Diode). Since the present invention improves the reception efficiency of photoacoustic waves, the light source can be a low power LD or LED instead of a high power individual laser. In addition, in order to generate excitation light of an arbitrary waveform as described later, LD or LED is generally preferable to a solid laser.
  • LD Laser Diode
  • LED Light Emitting Diode
  • the puncture needle 15 is an embodiment of the insert of the present invention, and is a needle to be punctured by a subject.
  • FIG. 2 is a cross-sectional view including a central axis extending in the longitudinal direction of the puncture needle 15.
  • the puncture needle 15 has an opening at the tip formed at an acute angle, and guides the laser light emitted from the hollow needle body 15a and the laser unit 13 to the vicinity of the opening of the puncture needle 15 It includes an optical fiber 15b (corresponding to the light guide member of the present invention) and a photoacoustic wave generation unit 15c that absorbs the laser light emitted from the optical fiber 15b to generate a photoacoustic wave.
  • the optical fiber 15b and the photoacoustic wave generation unit 15c are disposed in the hollow portion 15d of the puncture needle main body 15a.
  • the optical fiber 15b is connected to the laser unit 13 via, for example, an optical connector provided at the proximal end of the laser unit 13 side. For example, several ⁇ J (micro joules) of laser light is emitted from the light emitting end of the optical fiber 15 b.
  • the photoacoustic wave generation unit 15c is provided at the light emitting end of the optical fiber 15b, and is provided near the tip of the puncture needle 15 and on the inner wall of the puncture needle main body 15a.
  • the photoacoustic wave generation unit 15c absorbs the laser light emitted from the optical fiber 15b to generate a photoacoustic wave.
  • the photoacoustic wave generation unit 15 c is formed of, for example, an epoxy resin mixed with a black pigment, a polyurethane resin, a fluorine resin, a silicone rubber, or the like.
  • the direction of the photoacoustic wave generation part 15c is drawn larger than the optical fiber 15b, it is not limited to this,
  • the photoacoustic wave generation part 15c is comparable as the diameter of the optical fiber 15b.
  • the size of the Moreover, the pigment mixed to the photoacoustic wave generation part 15c is not limited to a black pigment, An organic or inorganic pigment
  • the photoacoustic wave generation unit 15 c is not limited to the above-described one, and a metal film or an oxide film having light absorbability with respect to the wavelength of laser light may be used as the photoacoustic wave generation unit.
  • a film of iron oxide having high light absorbability with respect to the wavelength of the laser light, or an oxide film such as chromium oxide and manganese oxide can be used as the photoacoustic wave generation unit 15c.
  • a metal film such as Ti (titanium) or Pt (platinum) having a light absorbability lower than that of an oxide but having high biocompatibility may be used as the photoacoustic wave generation unit 15c.
  • the position at which the photoacoustic wave generation unit 15c is provided is not limited to the inner wall of the puncture needle main body 15a.
  • a metal film or oxide film which is the photoacoustic wave generation unit 15c, is formed on the light emitting end of the optical fiber 15b to a film thickness of, for example, about 100 nm (nanometers) by evaporation or the like.
  • the light emitting end may be covered.
  • at least a portion of the laser light emitted from the light emitting end of the optical fiber 15b is absorbed by the metal film or oxide film covering the light emitting end, and the photoacoustic wave is transmitted from the metal film or oxide film. It occurs.
  • the probe 11 detects the photoacoustic wave emitted from the photoacoustic wave generation unit 15 c after the puncture needle 15 is punctured in the subject.
  • the probe 11 includes an acoustic wave detection unit 20 that detects a photoacoustic wave.
  • the acoustic wave detection unit 20 includes a piezoelectric element array in which a plurality of piezoelectric elements for detecting photoacoustic waves are arranged in one dimension, and a multiplexer.
  • the piezoelectric element is an ultrasonic transducer, for example, a piezoelectric element or a piezoelectric element composed of a polymer film such as polyvinylidene fluoride (PVDF).
  • the acoustic wave detection unit 20 includes an acoustic lens, an acoustic matching layer, a backing material, a control circuit of a piezoelectric element array, and the like.
  • the ultrasound unit 12 includes a reception circuit 21, a reception memory 22, a data separation unit 23, a photoacoustic image generation unit 24, an ultrasound image generation unit 25, an image output unit 26, a transmission control circuit 27, and a control unit 28.
  • the control unit 28 generates excitation light generation conditions based on the pulse width of the laser light generated in the laser unit 13 and the number of pulses with respect to the laser unit 13 as the light source based on the reception frequency characteristic of the probe 11 Have functions such as control to adjust the
  • the ultrasound unit 12 typically includes a processor, a memory, a bus, and the like. In the ultrasound unit 12, programs related to photoacoustic image generation processing, ultrasound image generation processing, control processing of the laser unit 13, and the like are incorporated in a memory.
  • control unit 28 configured by a processor
  • the functions of the data separation unit 23, the photoacoustic image generation unit 24, the ultrasound image generation unit 25, and the image output unit 26 are realized. That is, these units are configured by a memory and a processor in which a program is incorporated.
  • the hardware configuration of the ultrasound unit 12 is not particularly limited, and a plurality of integrated circuits (ICs), processors, application specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), memories, etc. It can be realized by appropriately combining
  • the receiving circuit 21 receives the detection signal output from the probe 11, and stores the received detection signal in the receiving memory 22.
  • the receiving circuit 21 typically includes a low noise amplifier, a variable gain amplifier, a low pass filter, and an analog to digital converter.
  • the detection signal of the probe 11 is amplified by a low noise amplifier, then gain adjusted according to the depth by a variable gain amplifier, high frequency components are cut by a low pass filter, and then converted to digital signals by an AD converter It is stored in the memory 22.
  • the receiving circuit 21 is configured of, for example, one IC.
  • the probe 11 outputs a detection signal of the photoacoustic wave and a detection signal of the reflected ultrasonic wave
  • the reception memory 22 stores detection signals (sampling data) of the photoacoustic wave and the reflected ultrasonic wave subjected to AD conversion.
  • the data separation unit 23 reads the detection signal of the photoacoustic wave from the reception memory 22 and transmits the detection signal to the photoacoustic image generation unit 24. Further, the detection signal of the reflected ultrasound is read from the reception memory 22 and transmitted to the ultrasound image generation unit 25.
  • the photoacoustic image generation unit 24 generates a photoacoustic image based on the detection signal of the photoacoustic wave detected by the probe 11.
  • the photoacoustic image generation process includes, for example, image reconstruction such as phase matching addition, detection, logarithmic conversion, and the like.
  • the ultrasound image generation unit 25 generates an ultrasound image (reflection acoustic wave image) based on the detection signal of the reflection ultrasound detected by the probe 11.
  • the ultrasonic image generation process also includes image reconstruction such as phase matching addition, detection, logarithmic conversion, and the like.
  • the image output unit 26 outputs the photoacoustic image and the ultrasound image to an image display unit 30 such as a display device.
  • the control unit 28 controls each unit in the ultrasonic unit 12.
  • the control unit 28 transmits a trigger signal to the laser unit 13 based on the excitation light generation condition, and causes the laser unit 13 to emit a laser beam. Further, according to the emission of the laser light, the sampling trigger signal is transmitted to the receiving circuit 21 to control the sampling start timing of the photoacoustic wave and the like.
  • the photoacoustic wave image and the ultrasound image may be displayed separately, or may be displayed in combination. By combining and displaying, it becomes possible to confirm where in the living body the tip of the puncture needle 15 is located, thereby enabling accurate and safe puncture.
  • the control unit 28 causes the laser unit 13 (light source) to generate laser light (excitation light) to be generated in the laser unit 13 based on the reception frequency characteristics of the probe 11 (acoustic wave detection means). Control is performed to adjust the excitation light generation condition based on the pulse width of and the number of pulses.
  • a center frequency is considered as a frequency characteristic here, it is good also as other frequency characteristics, such as peak frequency.
  • the control unit 28 performs control to adjust the excitation light generation condition based on the reception frequency characteristic of the probe 11 (acoustic wave detection means), that is, the center frequency in the sensitivity of the probe 11.
  • FIG. 3 is a graph showing the waveform of the excitation light
  • FIG. 4 is a graph showing the waveform of the photoacoustic wave
  • FIG. 5 is a graph showing the spectrum of the photoacoustic wave, and as shown in FIGS.
  • the pulse width t LP of the laser light is 1 / (2 ⁇ 6.5 M)
  • the pulse width t LP of the laser light is 1 / (2 ⁇ 6.5 M)
  • the reception frequency band of the probe 11 is a band having a width of 70% to 100% with respect to the center frequency, so the frequency of acoustic waves that can be received by the probe with a center frequency of 6.5 MHz (megahertz) is 3.2. It is considered to be about 9.8 MHz (megahertz).
  • the number of pulses of laser light is 1, as shown in FIG. 5, many photoacoustic waves other than the frequency that can be received by the probe 11 are generated, and the reception efficiency of the photoacoustic wave at the probe 11 is low.
  • the number of pulses of laser light is 2, most of the generated photoacoustic waves become frequencies that can be received by the probe 11, and the photoacoustic wave reception efficiency in the probe 11 is high.
  • the intensity of the photoacoustic wave generated at the second pulse can be made larger than that of the photoacoustic wave generated at the first pulse of the laser light. This is considered to be due to the following two effects.
  • the first is the temperature dependency of the photoacoustic wave generation unit 15c.
  • the intensity of the generated photoacoustic wave is proportional to the thermal expansion coefficient of the photoacoustic wave generation unit 15c.
  • the glass transition temperature of the black epoxy resin used for the photoacoustic wave generation unit 15c in the present embodiment is about 55 degrees, and the thermal expansion coefficient is 30 ⁇ 10 ⁇ 6 / ° C., 100 ⁇ below and above the glass transition temperature, respectively. It is greatly changed to 10 -6 / ° C. It is generally said that the thermal expansion coefficient does not change suddenly at the glass transition temperature, but changes stepwise at the near temperature (Epoxy technology company application guide).
  • the thermal expansion coefficient gradually increases in the vicinity of 55 degrees, and the intensity of the generated photoacoustic wave also gradually increases in the vicinity of 55 degrees.
  • the first pulse of the excitation light reaches the photoacoustic wave generation unit 15c
  • the light is absorbed and a photoacoustic wave is generated.
  • the temperature of the photoacoustic wave generation unit 15c rises due to the absorption of light energy.
  • the second pulse reaches the photoacoustic wave generation unit 15c, but the temperature of the photoacoustic wave generation unit 15c is higher than that of the first pulse, so the thermal expansion coefficient becomes high, and as shown in FIG.
  • the intensity of the photoacoustic wave also increases.
  • the second is the superposition of photoacoustic waves.
  • the photoacoustic wave is generated in all directions in the photoacoustic wave generation unit 15c.
  • the photoacoustic wave reaching the probe 11 is a superposition of one coming from the photoacoustic wave generation part 15 c directly in the probe direction and one coming from the photoacoustic wave generation part 15 c not directly but after being reflected by the needle tube toward the probe 11.
  • the center frequency of the generated photoacoustic wave is 9 MHz (megahertz)
  • the center wavelength of the photoacoustic wave in the photoacoustic wave generation unit 15c which is an epoxy resin (sound velocity 2500 to 3000 m / s (meters / second)) is 0 It is considered to be about .3 mm (millimeter).
  • the outer diameter of the optical fiber is about 0.15 mm (millimeter)
  • the distance from the center of the optical fiber to the needle tube is also about 0.15 mm (millimeter)
  • the photoacoustic wave directed from the photoacoustic wave generator 15c directly to the probe The path difference between the light beam reflected by the needle tube and the photoacoustic wave traveling in the probe direction is about 0.3 mm (millimeters).
  • the path difference corresponds to one wavelength, it is generated by the photoacoustic wave that is generated by the first pulse of the laser light and reflected by the needle tube and then travels in the probe direction and the second pulse of the laser light.
  • the photoacoustic waves coming toward the probe direction strengthen each other by superposition.
  • the path difference does not necessarily have to be an integral multiple of the wavelength, and can be reinforced even in the vicinity thereof.
  • the amplitude of the second pulse is larger than that of the first pulse.
  • an effect that can be suitably used is at least It can be seen that the pulse repetition period occurs in the range of 3 ⁇ s (microseconds) or less.
  • t LP t LR / 2
  • Fc 1 / between the pulse width t LP of the laser light, the repetition cycle t LR of the pulse of the laser light, and the center frequency Fc of the probe 11.
  • t LR t LR / 2
  • Fc 1 / between the pulse width t LP of the laser light, the repetition cycle t LR of the pulse of the laser light, and the center frequency Fc of the probe 11.
  • Fc 1 / between the pulse width t LP of the laser light, the repetition cycle t LR of the pulse of the laser light, and the center frequency Fc of the probe 11.
  • t LR ⁇ 3 ⁇ s (microseconds)
  • this corresponds to Fc> 0.33 MHz (megahertz)
  • at least the probe 11 with a center frequency of 0.33 MHz (megahertz) or more has the present effect. It can be seen that can be used.
  • the center frequency of the ultrasound probe 11 is 1 MHz (megahertz)
  • Bandwidth is broadened. The bandwidth of the photoacoustic wave generated can also be adjusted by utilizing this effect.
  • the generation efficiency of the photoacoustic wave in the puncture needle 15 can be enhanced and the reception efficiency of the photoacoustic wave in the probe 11 can be enhanced by performing the control described above, the visible depth of the puncture needle 15 in the photoacoustic image Can be significantly improved.
  • the number of pulses of the laser beam is not limited to two, and may be three or more.
  • the photoacoustic image generation unit 24 correct the tip position of the puncture needle 15 in the photoacoustic image according to the excitation light generation condition.
  • the center frequency of the photoacoustic wave generated in the object and the center frequency in the sensitivity of the probe 11 do not necessarily have to coincide with each other.
  • the center frequency of the photoacoustic wave may be set at an arbitrary position in the frequency band in the sensitivity of the probe 11 from the requirement of image quality and the like.
  • the photoacoustic image generation apparatus 10 according to the present embodiment is different from the photoacoustic image generation apparatus 10 according to the first embodiment only in the control method of the laser unit 13 (light source) in the control unit 28. Since the configuration is the same, the description of the same part is omitted.
  • control unit 28 is based on the reception frequency characteristics of the probe 11 (acoustic wave detection means) and the depth of the tip position of the puncture needle 15 with respect to the laser unit 13 (light source) at the time of photoacoustic image acquisition.
  • the pulse width of the laser light (excitation light) generated in the laser unit 13 so that the frequency characteristic of the photoacoustic wave immediately before the probe 11 approaches the reception frequency characteristic of the probe 11 (acoustic wave detection means), and Control is performed to adjust the excitation light generation condition based on the number of pulses and the pulse repetition period.
  • a center frequency is considered as a frequency characteristic here, it is good also as other frequency characteristics, such as peak frequency.
  • FIG. 7 is a graph showing the waveform of excitation light
  • FIG. 8 is a graph showing the spectrum of photoacoustic waves. As shown in FIG.
  • the excitation light generation condition (laser light L (excitation light) such that the center frequency of the photoacoustic wave generated in the subject M is 6.5 MHz (megahertz)
  • the pulse width t LP of 77 ns (nanoseconds), the pulse repetition period t LR of laser light L 154 ns (nanoseconds) was set, but the generated photoacoustic wave is attenuated in the subject M (In particular, as the high frequency component is attenuated more,) the center frequency of the photoacoustic wave immediately before the probe 11 changes from 6.5 MHz (megahertz) to a lower center frequency, as shown in FIG.
  • the excitation light generation condition is set so that the center frequency of the photoacoustic wave immediately before the probe 11 approaches the center frequency in the sensitivity of the probe 11 in consideration of the attenuation in the subject M. .
  • FIG. 9 is a graph showing the waveform of excitation light
  • FIG. 10 is a graph showing the spectrum of photoacoustic waves.
  • the number of pulses of the laser light L is 2, the pulse width t LP of the laser light L 62.5 ns (nanoseconds), and the pulse repetition period t LR of the laser light L 125 ns (nano In the case of second), as shown in FIG.
  • the center frequency of the photoacoustic wave immediately before the probe 11 can be set to 6.5 MHz (megahertz). Thereby, the receiving efficiency of the photoacoustic wave in the probe 11 can be raised rather than the said 1st Embodiment.
  • a plurality of patterns of excitation light generation conditions such that the center frequency of the photoacoustic wave immediately before the probe 11 and the center frequency in the sensitivity of the probe 11 are close to each other as a table in the ultrasonic unit 12 for each type of probe 11 in advance. (For example, when the tip position of the puncture needle 15 is located at a shallow location, for being located at an intermediate location, for being located at a deep location, etc.) and stored so that the user can select them Is desirable.
  • the detection conditions of the photoacoustic wave be optimized in accordance with each mode.
  • the excitation light generation condition may be automatically switched in accordance with the photoacoustic image or the image depth (maximum depth in the image) or the focal depth of an ultrasound image to be synthesized with the photoacoustic image.
  • the number of pulses of the laser beam is not limited to two, and may be three or more.
  • the photoacoustic image generation unit 24 it is desirable for the photoacoustic image generation unit 24 to correct the object position in the photoacoustic image according to the excitation light generation condition.
  • the center frequency of the photoacoustic wave immediately before the probe 11 and the center frequency in the sensitivity of the probe 11 do not necessarily have to coincide with each other.
  • the center frequency of the photoacoustic wave may be set at an arbitrary position in the frequency band in the sensitivity of the probe 11 from the requirement of image quality and the like.
  • the photoacoustic image generation apparatus 10 according to the present embodiment is different from the photoacoustic image generation apparatus 10 according to the first embodiment only in the control method of the laser unit 13 (light source) in the control unit 28. Since the configuration is the same, the description of the same part is omitted.
  • control unit 28 is based on the reception frequency characteristics of the probe 11 (acoustic wave detection means) and the depth of the tip position of the puncture needle 15 with respect to the laser unit 13 (light source) at the time of photoacoustic image acquisition. Excitation based on the pulse width of the laser light (excitation light) generated in the laser unit 13, the number of pulses, and the repetition period of the pulse so as to obtain appropriate reception characteristics such as resolution priority or sensitivity priority. Regarding the light generation condition, control is performed to select an optimum setting from among a plurality of settings in which the center frequency of the photoacoustic wave generated in the subject M is different. In addition, although a center frequency is considered as a frequency characteristic here, it is good also as other frequency characteristics, such as peak frequency.
  • the photoacoustic wave generated in the subject is attenuated in the subject (in particular, it attenuates more as the high frequency component) reaches the probe 11. Therefore, when the tip position of the puncture needle 15 is at a deep position, the excitation light generation condition is adjusted so that a low-frequency photoacoustic wave with a small attenuation rate per unit length is generated, and a shallow position. Since the influence of attenuation is small, the excitation light generation conditions are adjusted so that a high-resolution photoacoustic wave with high resolution is generated, and a more desirable photoacoustic image is obtained at each depth.
  • FIG. 11 is a graph showing the waveform of excitation light
  • FIG. 12 is a graph showing the spectrum of photoacoustic waves. As shown in FIG.
  • the conditions are a pulse width t LP of 62.5 ns (nanoseconds) of the laser light L (excitation light), and a repetition cycle t LR of 125 ns (nanoseconds) of the pulses of the laser light L. Further, the spectrum of the photoacoustic wave generated under these conditions is as shown in FIG.
  • FIG. 13 which is a graph showing the spectrum of the photoacoustic wave
  • the depth of the tip position of the puncture needle 15 is shallow (for example, 1 cm (centimeter))
  • the influence of attenuation in the subject is small.
  • the difference in intensity between the two photoacoustic waves is small.
  • the high frequency waveform may be selected with emphasis on resolution.
  • the main component of the high frequency photoacoustic wave is in the receivable frequency band (about 3.2 to 9.8 MHz (megahertz)) of the probe having a center frequency of 6.5 MHz (megahertz).
  • FIG. 14 which is a graph showing the spectrum of the photoacoustic wave
  • the tip position of the puncture needle 15 is deep (for example, 8 cm (centimeter)
  • the attenuation in the subject is large.
  • the difference in intensity between the two photoacoustic waves is large.
  • the low frequency waveform may be selected with emphasis on sensitivity.
  • the main component of the low frequency photoacoustic wave is in the receivable frequency band (about 3.2 to 9.8 MHz (megahertz)) of the probe having a center frequency of 6.5 MHz (megahertz).
  • a plurality of patterns of excitation light generation conditions such that the center frequency of the photoacoustic wave immediately before the probe 11 and the center frequency in the sensitivity of the probe 11 are close to each other as a table in the ultrasonic unit 12 for each type of probe 11 in advance. (For example, when the tip position of the puncture needle 15 is located at a shallow location, for being located at an intermediate location, for being located at a deep location, etc.) and stored so that the user can select them Is desirable.
  • the detection conditions of the photoacoustic wave be optimized in accordance with each mode.
  • the excitation light generation condition may be automatically switched in accordance with the photoacoustic image or the image depth (maximum depth in the image) or the focal depth of an ultrasound image to be synthesized with the photoacoustic image.
  • the number of pulses of the laser beam is not limited to three, and may be two or more.
  • the photoacoustic image generation unit 24 it is desirable for the photoacoustic image generation unit 24 to correct the object position in the photoacoustic image according to the excitation light generation condition.
  • the center frequency of the photoacoustic wave immediately before the probe 11 and the center frequency in the sensitivity of the probe 11 do not necessarily have to coincide with each other.
  • the center frequency of the photoacoustic wave may be set at an arbitrary position in the frequency band in the sensitivity of the probe 11 from the requirement of the image quality and the like.
  • the puncture needle 15 was used as one embodiment of an insert, as an insert, it is not limited to this.
  • the insert may be a radiofrequency ablation needle containing an electrode used for radiofrequency ablation, or a catheter inserted into a blood vessel.
  • the catheter may be inserted into a blood vessel. It may be a guide wire of Alternatively, it may be an optical fiber for laser treatment.
  • the insert of the present invention is not limited to a needle such as an injection needle, and may be a biopsy needle used for a biopsy. That is, the biopsy needle may be a biopsy needle which can be punctured into a subject to be examined in a living body to collect a tissue at a biopsy site in the subject. In that case, the photoacoustic wave may be generated in a collection unit (suction port) for suctioning and collecting the tissue at the biopsy site.
  • the needle may also be used as a guiding needle for deep puncture, such as subcutaneous and intra-abdominal organs.
  • an insert and a photoacoustic measuring device of the present invention are not limited only to the above-mentioned embodiment, and various modification from composition of the above-mentioned embodiment Also, modifications are included in the scope of the present invention.

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  • Life Sciences & Earth Sciences (AREA)
  • Health & Medical Sciences (AREA)
  • Biomedical Technology (AREA)
  • Biophysics (AREA)
  • Nuclear Medicine, Radiotherapy & Molecular Imaging (AREA)
  • Pathology (AREA)
  • Radiology & Medical Imaging (AREA)
  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Heart & Thoracic Surgery (AREA)
  • Medical Informatics (AREA)
  • Molecular Biology (AREA)
  • Surgery (AREA)
  • Animal Behavior & Ethology (AREA)
  • General Health & Medical Sciences (AREA)
  • Public Health (AREA)
  • Veterinary Medicine (AREA)
  • Ultra Sonic Daignosis Equipment (AREA)

Abstract

L'invention concerne un dispositif de génération d'images photoacoustiques offrant une profondeur visible améliorée des images photoacoustiques en imagerie photoacoustique à l'aide d'un article inséré comprenant une unité de génération d'ondes photoacoustiques agencée à proximité de son extrémité distale. Un procédé d'acquisition d'images destiné à être utilisé conjointement avec le dispositif de génération d'images photoacoustiques est en outre décrit. Une unité de commande du dispositif de génération d'images photoacoustiques procède à un réglage des conditions de génération de lumière d'excitation d'une source de lumière à laquelle l'unité de génération d'ondes photoacoustiques agencée sur l'extrémité distale de l'article inséré est exposée, où lesdites conditions se basent sur la largeur d'impulsion et les multiples décomptes d'impulsions de la lumière d'excitation générée par la source de lumière, en fonction des propriétés de fréquence de réception d'un moyen de détection d'ondes acoustiques.
PCT/JP2018/026597 2017-08-29 2018-07-13 Dispositif de génération d'images photoacoustiques et procédé d'acquisition d'images WO2019044212A1 (fr)

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Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2015037519A (ja) * 2013-01-09 2015-02-26 富士フイルム株式会社 光音響画像生成装置及び挿入物
JP2016047077A (ja) * 2014-08-27 2016-04-07 プレキシオン株式会社 光音響画像化装置

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2015037519A (ja) * 2013-01-09 2015-02-26 富士フイルム株式会社 光音響画像生成装置及び挿入物
JP2016047077A (ja) * 2014-08-27 2016-04-07 プレキシオン株式会社 光音響画像化装置

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
"ELECTRONIC INDUSTRIES ASSOCIATION OF JAPAN; CORONA PUBLISHING CO., LTD.), non-official translation (Revision of medical ultrasonic instrument handbook)", 20 January 1997 (1997-01-20), pages 147 *

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