WO2016204303A1 - Photoacoustic imaging device - Google Patents

Photoacoustic imaging device Download PDF

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Publication number
WO2016204303A1
WO2016204303A1 PCT/JP2016/068313 JP2016068313W WO2016204303A1 WO 2016204303 A1 WO2016204303 A1 WO 2016204303A1 JP 2016068313 W JP2016068313 W JP 2016068313W WO 2016204303 A1 WO2016204303 A1 WO 2016204303A1
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WO
WIPO (PCT)
Prior art keywords
light source
unit
source unit
current value
peak current
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Application number
PCT/JP2016/068313
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French (fr)
Japanese (ja)
Inventor
中塚　均
裕介 繁田
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プレキシオン株式会社
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Publication of WO2016204303A1 publication Critical patent/WO2016204303A1/en

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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
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N29/00—Investigating or analysing materials by the use of ultrasonic, sonic or infrasonic waves; Visualisation of the interior of objects by transmitting ultrasonic or sonic waves through the object
    • G01N29/22—Details, e.g. general constructional or apparatus details
    • G01N29/24—Probes
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N29/00—Investigating or analysing materials by the use of ultrasonic, sonic or infrasonic waves; Visualisation of the interior of objects by transmitting ultrasonic or sonic waves through the object
    • G01N29/34—Generating the ultrasonic, sonic or infrasonic waves, e.g. electronic circuits specially adapted therefor

Definitions

  • the present invention relates to a photoacoustic imaging apparatus, and more particularly to a photoacoustic imaging apparatus including a light source unit.
  • Patent Document 1 a photoacoustic imaging apparatus including a light source 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.
  • a Q-switch pulse laser light source requires an optical surface plate and a strong housing for suppressing characteristic fluctuations due to vibration of the optical system. .
  • the structure of the photoacoustic imaging apparatus of the said patent document 1 becomes comparatively large. Therefore, in order to suppress the increase in the size of the photoacoustic imaging apparatus of Patent Document 1, a configuration in which a light emitting element such as a light emitting diode element is provided in the light source unit (light source unit) instead of the Q switch pulse laser light source is considered. It is done.
  • 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.
  • a light-emitting element such as a light-emitting diode element has a characteristic that a peak current value increases as a current flowing time (pulse width) increases.
  • the present invention has been made to solve the above-described problems, and one object of the present invention is to use a light-emitting element such as a light-emitting diode element in the light source section and to detect the detection frequency of the detection section. It is to provide a photoacoustic imaging apparatus capable of suppressing the reduction of the photoacoustic wave signal even when the signal is large.
  • a photoacoustic imaging apparatus includes a light source unit and an acoustic wave generated from within the subject due to light being irradiated to the subject by the light source unit. And a light source driving unit that supplies power to the light source unit to drive the light source unit, and the light source driving unit has a predetermined peak current value of the power supplied to the light source unit. As described above, the voltage value of the power supplied to the light source unit is increased as the detection frequency of the detection unit increases.
  • the inventor of the present application increases the peak current value of the power supplied to the light source unit to a predetermined peak current value as the voltage value of the power supplied to the light source unit increases. It has been found that the time until the peak current value of the power supplied to the light source unit reaches a predetermined peak current value becomes longer as the time becomes shorter and the voltage value of the power supplied to the light source unit is smaller. In other words, the larger the voltage value of the power supplied to the light source unit, the higher the speed at which the current value of the power supplied to the light source unit increases, and the smaller the voltage value of the power supplied to the light source unit, the more supplied to the light source unit. It has been found that the speed at which the current value of the power to be increased decreases. The inventor of the present application has come up with the present invention by paying attention to this point.
  • the light source driving unit is configured so that the peak current value of the power supplied to the light source unit becomes a predetermined peak current value.
  • the voltage value of the power supplied to the light source unit is configured to increase as the detection frequency increases.
  • the photoacoustic wave signal can be suppressed from becoming small. As a result, it is possible to suppress the acoustic wave signal from becoming small even when a light emitting element such as a light emitting diode element is used for the light source unit and when the detection frequency of the detection unit is high.
  • the light source driving unit sets the pulse width of light emitted from the light source unit based on the detection frequency of the detection unit, and the smaller the pulse width, the light source The voltage value of the electric power supplied to the unit is increased.
  • the smaller the pulse width the shorter the time until the peak current value of the power supplied to the light source unit reaches the predetermined peak current value, so even when the pulse width is reduced,
  • the peak current value of the power supplied to the light source unit can be set to a predetermined peak current value.
  • the light source driving unit includes n light emitting elements connected in series with each other, the pulse width is tw, the predetermined peak current value is Io, and the predetermined proportionality constant is k.
  • the voltage value of the electric power supplied to the light source unit is set to the voltage value V expressed by the equation (1).
  • V n ⁇ 1 / k ⁇ 1 / tw ⁇ Io (1)
  • the light source drive unit is the maximum frequency of the acoustic wave that can be detected by the detection unit The larger the is, the smaller the pulse width is set.
  • 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 light source driving unit is configured so that the peak current value of the power supplied to the light source unit becomes a predetermined peak current value based on the response characteristics of the light source unit.
  • the voltage value of the electric power supplied to the light source unit is set.
  • the light source driving unit is supplied to the light source unit so that the peak current value of the power supplied to the light source unit becomes a predetermined peak current value based on the response characteristics of the light source unit.
  • the light source unit includes a first light source that emits light having a first wavelength and a second light source that emits light having a second wavelength different from the first wavelength
  • the light source driving unit includes: Based on the response characteristics of the first light source and the response characteristics of the second light source, the peak current value of the power supplied to the first light source and the peak current value of the power supplied to the second light source are substantially equal to each other.
  • the first voltage value of the power supplied to the first light source and the second voltage value of the power supplied to the second light source are respectively set.
  • the response characteristic of the light source unit is different depending on the wavelength.
  • the light amount (peak current value) of the pulsed light from the first light source and the pulse from the second light source There is a difference between the amount of light (peak current value).
  • the intensity of the acoustic wave caused by the pulsed light from the first light source and the intensity of the acoustic wave caused by the pulsed light from the second light source a relatively complicated considering the difference in the amount of light. Since correction is necessary, it is considered that the signal processing of the photoacoustic imaging apparatus is complicated.
  • the peak current value of the power supplied to the first light source and the peak current value of the power supplied to the second light source can be made substantially equal. Therefore, when comparing the intensity of the acoustic wave caused by the pulsed light from the first light source and the intensity of the acoustic wave caused by the pulsed light from the second light source, there is no need for relatively complicated correction. Therefore, it is possible to prevent the signal processing of the photoacoustic imaging apparatus from becoming complicated.
  • the light source drive unit preferably has a correspondence relationship between at least one of the identification information of the detection unit and the identification information of the light source unit and the voltage value of the power supplied to the light source unit. Based on the table to represent, it is comprised so that the voltage value of the electric power supplied to a light source part may be set. If comprised in this way, the voltage value of the electric power supplied to a light source part can be set easily by the part which does not need to be calculated using a comparatively complicated calculation formula by using a table.
  • the light source section preferably includes at least one of a light emitting diode element and a semiconductor laser 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.
  • the present invention as described above, even when a light emitting element such as a light emitting diode element is used and the detection frequency of the detection unit is high, it is possible to suppress the acoustic wave signal from becoming small.
  • FIG. 1 is a block diagram illustrating an overall configuration of a photoacoustic imaging apparatus according to a first embodiment of the present invention. It is the block diagram which showed the structure regarding irradiation of the pulsed light of the photoacoustic imaging device by 1st Embodiment of this invention. It is a figure for demonstrating the characteristic of the detection frequency of the detection part by 1st Embodiment of this invention. It is a figure for demonstrating the relationship between the pulsed light and peak current value of the photoacoustic imaging device by 1st Embodiment of this invention. It is a figure for demonstrating the relationship between the voltage value applied to the light source part of the photoacoustic imaging device by 1st Embodiment of this invention, and a peak current value.
  • 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 unit 11 includes a plurality of light emitting diode elements 11 a.
  • the light emitting diode element 11 a is configured as a plurality of light emitting element groups 11 b in which a plurality (n) of light emitting diode elements 11 a are connected in series, and the light emitting element group 11 b is connected to the light source driving unit 21.
  • the light emitting diode element 11a is an example of the “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 light emitting diode 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 21 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 the generated power (apply a voltage value V) to the anode side of the light emitting diode element 11a. Has been.
  • the switch units 21b to 21d have one side connected to the cathode side of the light emitting diode element 11a of the light source unit 11, and the other side 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.
  • FET Field Effect Transistor
  • the voltage value on the cathode side of the light emitting diode element 11a is lowered (grounded), so that a potential difference (approximately) between the anode side and the cathode side of the light emitting diode element 11a.
  • a voltage value V) is generated, and a current flows through the light emitting diode element 11a. That is, the magnitude of the current value flowing through the light emitting diode element 11a is emitted from the light source unit 11 corresponding to the magnitude of the pulse width tw of the pulsed light emitted from the light source unit 11 when the switch units 21b to 21d are turned on. This corresponds to the magnitude of the amount of pulsed light to be generated.
  • 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 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. That is, when 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.
  • FIG. 4 illustrates a waveform of a current flowing through the light source unit 11 when the voltage value V applied to the light source unit 11 is constant.
  • the control unit 22 transmits the light trigger signal to the switch units 21b to 21d during the period ⁇ 1 (the period from the time point t1 to t2)
  • the pulse width tw of the light emitted from the light source unit 11 is Tw1 (for example, 100 ns).
  • the pulse width tw of the pulsed light is described as the time width of the full width at half maximum of the current value flowing through the light emitting diode element 11a.
  • the current value flowing through the light source unit 11 gradually increases from time t1 to time t2, and the peak current value Ip, which is the maximum value of the current value flowing through the light-emitting diode element 11a, is increased at time t2.
  • I1 for example, 15A
  • the value of the current flowing through the light emitting diode element 11a gradually decreases after time t2, and becomes substantially zero at time t3. That is, power is supplied from the light source driving unit 21 so that the waveform of the current value flowing through the light emitting diode element 11a (the waveform of the pulsed light) has a substantially triangular wave shape.
  • control unit 22 transmits light emitted from the light source unit 11 when the optical trigger signal is transmitted to the switch units 21b to 21d during the period ⁇ 2 longer than the period ⁇ 1 (period from the time point t1 to t4).
  • the pulse width tw becomes tw2 (for example, 500 ns).
  • the current value flowing through the light source unit 11 gradually increases from time t1 to time t4, and at time t4, the peak current value Ip becomes I2 larger than the current value I1 (for example, 75A). Then, the value of the current flowing through the light emitting diode element 11a gradually decreases after time t4 and becomes substantially zero at time t5.
  • the peak current value Ip of the current flowing through the light source unit 11 is The larger the pulse width tw, the larger, and the smaller the pulse width tw, the smaller.
  • FIG. 5 illustrates a waveform of a current flowing through the light source unit 11 when the voltage value V applied to the light source unit 11 is changed.
  • the voltage value V applied to the light source unit 11 is set to the voltage values V1, V2, and V3 in a state where the period during which the voltage is applied to the light source unit 11 is constant (period ⁇ 3 (from time t11 to t13)).
  • 4 shows the waveforms of the respective current values in the case where the voltage values V1, V2, and V3 are assumed to have a relationship of V1> V2> V3.
  • the peak current value Ip of the current flowing through the light source unit 11 is the current value I3 in the case of the voltage value V1, the current value I4 in the case of the voltage value V2, and the current value I5 in the case of the voltage value V3. Note that the relationship of I3> I4> I5 is satisfied.
  • the peak current value Ip of power supplied to the light source unit 11 reaches the set peak current value Io as the voltage value V of power supplied to the light source unit 11 increases.
  • the current value flowing through the light emitting diode element 11a reaches the set peak current value Io at time t12 prior to time t13.
  • the current value flowing through the light emitting diode element 11a reaches the set peak current value Io at time t13.
  • the current value flowing through the light emitting diode element 11a reaches the set peak current value Io after time t13.
  • the speed at which the current value of the power supplied to the light source unit 11 increases increases.
  • the light source driving unit 21 detects the detection frequency of the detection unit 12 (detected by the detection unit 12 so that the peak current value Ip of the power supplied to the light source unit 11 becomes the set peak current value Io.
  • the voltage value V of the power supplied to the light source unit 11 is increased as the maximum frequency fmax) that can be increased is increased. This will be specifically described below.
  • the set peak current value Io is set in advance by the light source driving unit 21 (control unit 22).
  • the set peak current value Io generates a sufficiently large acoustic wave A from the subject P when the subject P is irradiated with pulsed light generated by the set peak current value Io flowing to the light source unit 11. It is set to a possible value.
  • the set peak current value Io is set as I4.
  • the light source drive part 21 (control part 22) irradiates from the light source part 11 based on the detection frequency (maximum frequency fmax which the detection part 12 can detect) of the detection part 12.
  • FIG. The light pulse width tw is set.
  • the pulse width tw of the light source unit 11 is a light emitting diode element by the light source driving unit 21 (control unit 22) when the maximum frequency of the acoustic wave A that can be detected by the detection unit 12 is fmax.
  • the pulse width tw of the pulsed light is set to the pulse width tw represented by the following expression (2) by adjusting the width of time during which voltage is applied to 11a (pulse width of the optical trigger signal). It is configured. 0.5 / fmax ⁇ tw ⁇ 1 / fmax (2)
  • the control unit 22 sets the pulse width tw to 0.5 / 7.5 MHz ⁇ tw ⁇ 1 / 7.5 MHz. To do. That is, the pulse width tw is set within a range of about 67 ns to about 133 ns. For example, when the control unit 22 sets the pulse width tw to 100 ns, the frequency distribution of the acoustic wave A generated due to the light irradiated by the light source unit 11 is detected as shown in FIG. The distribution corresponds to the frequency characteristics (see FIG. 3) of the acoustic wave A that can be detected by the unit 12.
  • the light source driving unit 21 can generate pulsed light having a desired set peak current value Io and a pulse width tw.
  • the control unit 22 sets the pulse width tw to be larger than 100 ns (pulse width ⁇ 4 (> ⁇ 3) of the optical trigger signal).
  • the voltage value V is similarly set to the voltage value V4 ( ⁇ V2) using the above equation (3).
  • the peak current value Ip is 8A. Further, when the voltage value V was 13 V, the peak current value Ip was 15A. Further, when the voltage value V was 20 V, the peak current value Ip was 22A. Further, when the voltage value V was 27 V, the peak current value Ip was 30 A. Further, when the voltage value V was 34V, the peak current value Ip was 39A. Further, when the voltage value V was 41 V, the peak current value Ip was 46 A. Further, when the voltage value V was 48V, the peak current value Ip was 52A. Further, when the voltage value V was 53 V, the peak current value Ip was 60A. Further, when the voltage value V was 59 V, the peak current value Ip was 66 A.
  • the detection frequency of the detection unit 12 (the maximum frequency thereof) is set so that the peak current value Ip of the power supplied to the light source unit 11 is the set peak current value Io.
  • the voltage value V of the electric power supplied to the light source unit 11 is increased as fmax) increases.
  • the light source driving unit 21 sets the pulse width tw of light emitted from the light source unit 11 based on the detection frequency of the detection unit 12, and the pulse width tw is small.
  • the configuration is such that the voltage value V of the power supplied to the light source unit 11 is increased.
  • the pulse width tw is smaller, the time until the peak current value Ip of the power supplied to the light source unit 11 reaches the set peak current value Io can be shortened. Therefore, even when the pulse width tw is decreased, The peak current value Ip of the power supplied to the light source unit 11 can be reliably set to the set peak current value Io.
  • the light source drive unit 21 includes n light emitting diode elements 11a connected in series with each other, the pulse width is tw, the set peak current value is Io, and the predetermined value is set. Is set to the voltage value V of the electric power supplied to the light source unit 11 to the voltage value V expressed by the above equation (3). Thereby, even when the number of light emitting diode elements 11a, the pulse width tw, and the set peak current value Io are changed, the peak current value of the power supplied to the light source unit 11 is obtained by using the above equation (3). The voltage value V for allowing Ip to become the set peak current value Io can be easily set.
  • the light source driving unit 21 is configured to set the pulse width tw to be smaller as the maximum acoustic wave frequency fmax that can be detected by the detection unit 12 is larger.
  • the acoustic wave A generated from the subject 12 is generated as an acoustic wave A having a frequency equal to or lower than the maximum frequency with a frequency having a reciprocal value of the pulse width tw irradiated to the subject P as a maximum frequency (FIG. 6).
  • the light source drive unit 21 is configured to set the pulse width tw to be smaller as the maximum frequency fmax of the acoustic wave that can be detected by the detection unit 12 is larger.
  • the maximum frequency of the acoustic wave A generated from the subject P can be increased as the maximum frequency fmax of the detection unit 12 is increased.
  • the maximum frequency fmax of the acoustic wave that can be detected by the detection unit 12 and the maximum frequency of the acoustic wave A generated from the subject P can be substantially matched, the acoustic wave A can be efficiently and efficiently transmitted. Can be generated.
  • the light source diode 11 is provided in the light source unit 11.
  • 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 configuration of the photoacoustic imaging apparatus 200 according to the second embodiment will be described with reference to FIGS.
  • the peak current value Ip of the power supplied to the light source unit 211 is set to the set peak current value Io.
  • the voltage value V of the power supplied to the light source unit 211 is set.
  • symbol is attached
  • the photoacoustic imaging apparatus 200 includes a probe main body 201 and an apparatus main body 202.
  • the probe main body unit 201 includes a light source unit 211 and a detection unit 212.
  • the apparatus main body 202 includes a light source driving unit 221, a control unit 222, and a storage unit 225.
  • the probe main body 201 is configured to be detachable from the cable 3, and is configured to be able to replace the probe main body 201 with another type of probe main body 201.
  • the light source unit 211 includes a plurality of light emitting diode elements 11a.
  • the light source unit 211 stores identification information (identification) 211b in advance.
  • the light source unit 211 is configured to be detachable from the probe main body unit 201, and is configured to be able to replace the light source unit 211 with another type of light source unit 211 (having different response characteristics). Yes.
  • identification information 212a is stored in advance.
  • the detection unit 212 is configured to be detachable from the probe main body unit 201, and the detection unit 212 is replaced with another type of detection unit 212 (different in the maximum frequency fmax). It is configured to be able to.
  • the light source driving unit 221 uses the light source unit 221 so that the peak current value Ip of the power supplied to the light source unit 211 becomes the set peak current value Io based on the response characteristics of the light source unit 211.
  • the voltage value V of the electric power supplied to 211 is set.
  • the light source driving unit 221 also includes a table 225 a representing the correspondence between the identification information 212 a of the detection unit 212 and the identification information 211 b of the light source unit 211 and the voltage value V of the power supplied to the light source unit 211.
  • the voltage value V of the power supplied to the light source unit 211 is set based on the above.
  • the storage unit 225 includes identification information 212 a of the detection unit 212, identification information 211 b of the light source unit 211, and a voltage value V of power supplied to the light source unit 211.
  • a table 225a representing the correspondence relationship is stored in advance. Note that the storage unit 225 may be configured to acquire the table 225a from an external device (not shown).
  • the table 225a includes a table indicating the correspondence between the identification information 212a of the detection unit 212 and the pulse width tw of the pulsed light from the light source unit 211.
  • the pulse widths “tw11”, “tw12”, and the like are set so as to correspond to the identification information “01”, “02”, and the like.
  • the pulse width tw corresponding to the identification information 212a of the detection unit 212 having a relatively large maximum frequency fmax is set to be relatively small.
  • the table 225a includes a table indicating the correspondence between the identification information 211b of the light source unit 211 and the voltage value V applied to the light source unit 211.
  • the voltage value V is set so as to correspond to the identification information and the pulse width tw.
  • the control unit 222 sets the voltage value V13.
  • the voltage value V set in the table 225a is set for each identification information 211b in consideration of the response characteristics of the light emitting diode element 11a of the light source unit 211.
  • the response characteristics of the present specification include not only the rising and falling characteristics of the light emitting diode element 11a, but also the proportionality constant k in the equation (3) of the photoacoustic imaging apparatus 100 according to the first embodiment described above. Information on the number n of the light emitting diode elements 11a and the set peak current value Io is included.
  • the control unit 222 acquires the identification information 212a of the detection unit 212 from the probe main body 201 via the cable 3, and sets the pulse width tw corresponding to the acquired identification information 212a. It is configured as follows. Then, the control unit 222 (light source driving unit 221) acquires the identification information 211b of the light source unit 211 from the probe main body unit 201 via the cable 3, and the voltage value corresponding to the acquired identification information 211b and the pulse width tw. It is configured to set V.
  • the light source driving unit 221 applies the set voltage value V to the light source unit 211, and the subject P is applied to the subject P in a state where the peak current value Ip of the current flowing through the light source unit 211 becomes the set peak current value Io. It is configured to emit pulsed light.
  • the light source driving unit 221 causes the peak current of power supplied to the light source unit 211 based on the response characteristics (identification information 211b and the table 225a) of the light source unit 211.
  • the voltage value V of the power supplied to the light source unit 211 is set so that the value Ip becomes the set peak current value Io.
  • the speed at which the value of the current flowing through the light source unit 211 increases according to the response characteristics of the light source unit 211 changes.
  • the light source driving unit 221 is configured so that the peak current value Ip of the power supplied to the light source unit 211 becomes the set peak current value Ip based on the response characteristics of the light source unit 211.
  • the voltage value V of the power supplied to the light source unit 211 it is possible to appropriately set the speed at which the current value of the power supplied to the light source unit 211 is increased.
  • the light source driving unit 221 causes the identification information 212a of the detection unit 212 and the identification information 211b of the light source unit 211 to be supplied to the light source unit 211.
  • the voltage value V of the power supplied to the light source unit 211 is set.
  • the voltage value V of the power supplied to the light source unit 211 can be easily set because it is not necessary to calculate using a relatively complicated calculation formula.
  • the configuration of the photoacoustic imaging apparatus 300 according to the third embodiment will be described with reference to FIGS.
  • the light source part (the 1st light source part 311 and the 2nd light source part 313) which can irradiate the pulse light which has a mutually different wavelength in the probe main-body part 301 is provided.
  • symbol is attached
  • the photoacoustic imaging apparatus 300 includes a probe main body 301 and an apparatus main body 302.
  • the probe main body 301 includes a detection unit 212, a first light source unit 311, and a second light source unit 313.
  • the apparatus main body 302 includes a light source driving unit 321, a control unit 322, and a storage unit 325.
  • the probe main body 301 is configured to be detachable from the cable 3, and is configured to be able to replace the probe main body 301 with another type of probe main body 301.
  • the probe main body 301 includes a first light source unit 311 that emits pulsed light having a wavelength of about 850 nm (center wavelength is about 850 nm), and a wavelength of about 760 nm that is different from the wavelength of about 850 nm. And a second light source unit 313 that emits pulsed light (having a center wavelength of about 760 nm). Then, the light source driving unit 321 uses the peak current value Ipa of power supplied to the first light source unit 311 and the second light source unit 313 based on the response characteristics of the first light source unit 311 and the response characteristics of the second light source unit 313.
  • the first voltage value Va of the power supplied to the first light source unit 311 and the first power value of the power supplied to the second light source unit 313 are set so that the peak current value Ipb of the power supplied to Two voltage values Vb are set.
  • the wavelength of about 850 nm is an example of the “first wavelength” in the claims.
  • the wavelength of about 760 nm is an example of the “second wavelength” in the claims.
  • identification information 311b is stored in the first light source unit 311 in advance.
  • the second light source unit 313 stores identification information 313b in advance.
  • the first light source unit 311 and the second light source unit 313 are configured to be detachable from the probe main body 301, respectively.
  • the detection unit 212 is configured in the same manner as the detection unit 212 according to the second embodiment, and stores identification information 212a in advance.
  • the storage unit 325 stores a table 325a.
  • control unit 321 includes identification information 212 a of the detection unit 212, identification information 311 b of the first light source unit 311, identification information 313 b of the second light source unit 313, and first power supplied to the first light source unit 311.
  • the first power value Va and the second power value Vb are configured to be set based on a table 325a representing a correspondence relationship between the power value Va and the second power value Vb of the power supplied to the second light source unit 313. Yes.
  • the table 325a includes combinations of identification information 212a of the detection unit 212, identification information 311b of the first light source unit 311 and identification information 313b of the second light source unit 313. Accordingly, the pulse width twa and voltage value Va of the pulsed light of the first light source unit 311 and the pulse width twb and voltage value Vb of the pulsed light of the second light source unit 313 are respectively set.
  • the pulse width twa and voltage value Va, and the pulse width twb and voltage value Vb are the response characteristics of the first light source unit 311 (first light emitting diode element 311a) and the second light source unit 313 (second light emitting diode element 313a). Response characteristics are set in consideration.
  • control unit 321 sets the pulse widths twa and twb and the voltage values Va and Vb based on the table 325a, and the first light source unit 311 and the second light source unit from the light source driving unit 322 according to the set conditions.
  • Each of 313 is configured to supply power.
  • the light source driving unit 322 applies a voltage corresponding to the pulse width twa (trigger signal ⁇ 11) and the voltage value Va to the first light source unit 311 based on a command from the control unit 321, A voltage corresponding to the width twb (trigger signal ⁇ 12) and the voltage value Vb is applied to the second light source unit 313.
  • the peak current value Ipa of the current flowing through the first light source unit 311 becomes the set peak current value Io
  • the peak current value Ipb of the current flowing through the second light source unit 313 becomes the set peak current value Io.
  • the light absorption characteristics differ depending on the detection target of the subject P.
  • the oxygenated hemoglobin has a larger extinction coefficient for light having a wavelength of 850 nm than that for deoxygenated hemoglobin, while the extinction coefficient for light having a wavelength of 760 nm is smaller for oxygenated hemoglobin than that of deoxygenated hemoglobin.
  • the first light source unit 311 can irradiate the subject P with pulsed light having a wavelength of 850 nm
  • the second light source unit 313 can irradiate the subject P with pulsed light having a wavelength of 760 nm.
  • the photoacoustic imaging apparatus 300 can determine, for example, whether the blood vessel is an artery or a vein by using the difference between the extinction coefficient of deoxygenated hemoglobin and the extinction coefficient of oxygenated hemoglobin. It is configured.
  • 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 probe light source unit 311 that emits pulsed light with a wavelength of about 850 nm and the pulsed light with a wavelength of about 760 nm that are different from the wavelength of about 850 nm are emitted to the probe main body 301.
  • a second light source unit 313 is provided.
  • the light source driving unit 321 uses the peak current value Ipa of power supplied to the first light source unit 311 and the second light source unit 313 based on the response characteristics of the first light source unit 311 and the response characteristics of the second light source unit 313.
  • the first voltage value Va of the power supplied to the first light source unit 311 and the first power value of the power supplied to the second light source unit 313 are set so that the peak current value Ipb of the power supplied to Two voltage values Vb are set.
  • the response characteristic of the light source unit is different depending on the wavelength. For this reason, when power having the same voltage value V is supplied to the first light source unit 311 and the second light source unit 313 having different wavelengths, the light amount of the pulsed light (peak current value Ipa from the first light source unit 311). ) And the light amount (peak current value Ipb) of the pulsed light from the second light source unit 313 is different.
  • the peak current value Ipa of power supplied to the first light source unit 311 and the peak current value of power supplied to the second light source unit 313 are configured as described above.
  • the peak current value Ipb can be made substantially equal, the intensity of the acoustic wave A caused by the pulsed light from the first light source unit 311 and the intensity of the acoustic wave A caused by the pulsed light from the second light source unit 313 , It is not necessary to make a relatively complicated correction, so that the signal processing of the photoacoustic imaging apparatus 300 can be prevented from becoming complicated.
  • the present invention is not limited to this.
  • a semiconductor laser element 411a may be used for the light source unit 411 as in the modification shown in FIG.
  • the control unit is configured to set the voltage value after setting the pulse width tw of the pulsed light. It is not limited to this.
  • the control unit (light source driving unit) may be configured to set the voltage value before setting the pulse width tw of the pulsed light. That is, the control unit (light source driving unit) increases the voltage value of the power supplied to the light source unit as the detection frequency of the detection unit increases so that the peak current value of the power supplied to the light source unit becomes the set peak current value. It suffices if it is configured to increase the size.
  • the table of the second embodiment may be configured as one table.
  • the table for setting the pulse width and the table for setting the voltage value are the same as the table for the third embodiment (see FIG. 12), like the tables for the second embodiment (see FIGS. 9 and 10).
  • You may comprise as a table separate from a table.
  • control unit is configured to acquire identification information from the detection unit and the light source unit, and to set the pulse width and voltage value based on the acquired identification information.
  • the present invention is not limited to this.
  • the control unit acquires the maximum frequency information and the response characteristic information instead of the identification information from the detection unit and the light source unit, and based on the acquired maximum frequency information and the response characteristic information, the pulse width and the voltage value It may be configured to set.
  • 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.

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Abstract

This photoacoustic imaging device 100 comprises a light source unit 11, a detection unit 12 that detects acoustic waves A generated from inside a test subject P caused by irradiating light onto the test subject P with the light source unit 11, and a light source drive unit 21 that drives the light source unit 11 by supplying power to the light source unit 11. The light source drive unit 21 is configured so that as the detection frequencies of the detection unit 12 are increased, the voltage V of the power supplied to the light source unit 11 is increased so that the peak current Ip of the power supplied to the light source unit 11 is a set peak current Io.

Description

光音響画像化装置Photoacoustic imaging device
　この発明は、光音響画像化装置に関し、特に、光源部を備えた光音響画像化装置に関する。 The present invention relates to a photoacoustic imaging apparatus, and more particularly to a photoacoustic imaging apparatus including a light source unit.
　従来、光源部を備えた光音響画像化装置が知られている（たとえば、特許文献１参照）。 Conventionally, a photoacoustic imaging apparatus including a light source unit is known (for example, see Patent Document 1).
　上記特許文献１には、光源ユニットを備えた光音響画像化装置が開示されている。この光音響画像化装置には、超音波探触子と、画像化部とが設けられている。光源ユニットは、Ｑスイッチパルスレーザ光源を含む。そして、この光音響画像化装置は、光源ユニットにより、被検体にレーザ光を照射して、超音波探触子により被検体から発生した音響波信号を検出するように構成されている。そして、画像化部は、超音波探触子により検出された音響波信号を画像化するように構成されている。また、この光音響画像化装置は、超音波探触子の周波数帯域に応じて、Ｑスイッチパルスレーザ光源からのパルス光のパルス幅を調整するように構成されている。 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.
　ここで、一般的に、Ｑスイッチパルスレーザ光源は、たとえば、発光ダイオード素子等の発光素子と異なり、光学系の振動による特性変動を抑制するための光学定盤や強固な筐体が必要になる。このため、上記特許文献１の光音響画像化装置の構造は、比較的大きくなると考えられる。そこで、上記特許文献１の光音響画像化装置の大型化を抑制するために、光源ユニット（光源部）に、Ｑスイッチパルスレーザ光源の代わりに、発光ダイオード素子等の発光素子を設ける構成が考えられる。 Here, in general, unlike a light emitting element such as a light emitting diode element, a Q-switch pulse laser light source requires an optical surface plate and a strong housing for suppressing characteristic fluctuations due to vibration of the optical system. . For this reason, it is thought that the structure of the photoacoustic imaging apparatus of the said patent document 1 becomes comparatively large. Therefore, in order to suppress the increase in the size of the photoacoustic imaging apparatus of Patent Document 1, a configuration in which a light emitting element such as a light emitting diode element is provided in the light source unit (light source unit) instead of the Q switch pulse laser light source is considered. It is done.
特開２０１３－１２８７２２号公報JP 2013-128722 A
　しかしながら、上記特許文献１の光音響画像化装置では、超音波探触子の周波数帯域に応じて、光源からのパルス光のパルス幅を調整するように構成されている。ここで、一般的に、発光ダイオード素子等の発光素子は、電流を流す時間（パルス幅）が長くなる程、ピーク電流値が大きくなる特性を有する。このため、上記特許文献１の光音響画像化装置に発光ダイオード素子等の発光素子を用いる構成では、超音波探触子の周波数帯域が大きい場合に、パルス幅が小さくなるように調整された場合（電流を流す時間が短い場合）に、ピーク電流値が光音響波信号を取得するために十分な大きさのピーク電流値に達しない場合があると考えられる。この場合、この光音響画像化装置では、光源からのパルス光の光量が十分な光量にならないため、被検体から発生する光音響波信号が小さくなるという不都合がある。したがって、この光音響画像化装置では、発光ダイオード素子等の発光素子を用いる場合で、かつ、超音波探触子（検出部）の周波数帯域（検出周波数）が大きい（パルス幅が小さい）場合には、音響波信号が小さくなるのを抑制することが困難であるという問題点がある。 However, 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. Here, in general, a light-emitting element such as a light-emitting diode element has a characteristic that a peak current value increases as a current flowing time (pulse width) increases. For this reason, in the configuration using a light-emitting element such as a light-emitting diode element in the photoacoustic imaging apparatus of Patent Document 1, when the pulse width is adjusted to be small when the frequency band of the ultrasonic probe is large It is considered that the peak current value may not reach a peak current value that is large enough to acquire the photoacoustic wave signal (when the current flow time is short). In this case, in this photoacoustic imaging apparatus, since the light amount of the pulsed light from the light source is not sufficient, there is a disadvantage that the photoacoustic wave signal generated from the subject becomes small. Therefore, in this photoacoustic imaging apparatus, when a light emitting element such as a light emitting diode element is used and the frequency band (detection frequency) of the ultrasonic probe (detection unit) is large (pulse width is small). However, it is difficult to suppress the acoustic wave signal from becoming small.
　この発明は、上記のような課題を解決するためになされたものであり、この発明の１つの目的は、光源部に発光ダイオード素子等の発光素子を用いる場合で、かつ、検出部の検出周波数が大きい場合にも、光音響波信号が小さくなるのを抑制することが可能な光音響画像化装置を提供することである。 The present invention has been made to solve the above-described problems, and one object of the present invention is to use a light-emitting element such as a light-emitting diode element in the light source section and to detect the detection frequency of the detection section. It is to provide a photoacoustic imaging apparatus capable of suppressing the reduction of the photoacoustic wave signal even when the signal is large.
　上記目的を達成するために、この発明の一の局面による光音響画像化装置は、光源部と、光源部により被検体に光が照射されることに起因して被検体内から発生する音響波を検出する検出部と、光源部に電力を供給して光源部を駆動させる光源駆動部とを備え、光源駆動部は、光源部に供給する電力のピーク電流値が所定のピーク電流値になるように、検出部の検出周波数が大きいほど、光源部に供給する電力の電圧値を大きくするように構成されている。 In order to achieve the above object, a photoacoustic imaging apparatus according to one aspect of the present invention includes a light source unit and an acoustic wave generated from within the subject due to light being irradiated to the subject by the light source unit. And a light source driving unit that supplies power to the light source unit to drive the light source unit, and the light source driving unit has a predetermined peak current value of the power supplied to the light source unit. As described above, the voltage value of the power supplied to the light source unit is increased as the detection frequency of the detection unit increases.
　ここで、本願発明者が鋭意検討した結果、本願発明者は、光源部に供給する電力の電圧値が大きい程、光源部に供給する電力のピーク電流値が所定のピーク電流値に達するまでの時間が短くなり、光源部に供給する電力の電圧値が小さい程、光源部に供給する電力のピーク電流値が所定のピーク電流値に達するまでの時間が長くなることを見出した。言い換えると、光源部に供給する電力の電圧値が大きい程、光源部に供給する電力の電流値が上昇する速度が大きくなり、光源部に供給する電力の電圧値が小さい程、光源部に供給する電力の電流値が上昇する速度が小さくなることを見出した。本願発明者は、この点に着目することによって、本願発明を想到するに至った。 Here, as a result of intensive studies by the inventor of the present application, the inventor of the present application increases the peak current value of the power supplied to the light source unit to a predetermined peak current value as the voltage value of the power supplied to the light source unit increases. It has been found that the time until the peak current value of the power supplied to the light source unit reaches a predetermined peak current value becomes longer as the time becomes shorter and the voltage value of the power supplied to the light source unit is smaller. In other words, the larger the voltage value of the power supplied to the light source unit, the higher the speed at which the current value of the power supplied to the light source unit increases, and the smaller the voltage value of the power supplied to the light source unit, the more supplied to the light source unit. It has been found that the speed at which the current value of the power to be increased decreases. The inventor of the present application has come up with the present invention by paying attention to this point.
　すなわち、この発明の一の局面による光音響画像化装置では、上記のように、光源駆動部を、光源部に供給する電力のピーク電流値が所定のピーク電流値になるように、検出部の検出周波数が大きいほど、光源部に供給する電力の電圧値を大きくするように構成する。これにより、検出部の検出周波数が大きい場合にパルス幅を小さくする場合（光源部に電流を流す時間が短い場合）でも、光源部に供給する電力の電圧値を大きくすることにより電流値が上昇する速度を大きくすることができる。この結果、光源部に供給する電力のピーク電流値を所定のピーク電流値にすることができる。そして、光源部に供給する電力の電流値が所定のピーク電流値（光音響波信号を取得するために十分な大きさのピーク電流値）に達しない状態になるのを抑制することができるので、光音響波信号が小さくなるのを抑制することができる。その結果、光源部に発光ダイオード素子等の発光素子を用いる場合で、かつ、検出部の検出周波数が大きい場合にも、音響波信号が小さくなるのを抑制することができる。 That is, in the photoacoustic imaging apparatus according to one aspect of the present invention, as described above, the light source driving unit is configured so that the peak current value of the power supplied to the light source unit becomes a predetermined peak current value. The voltage value of the power supplied to the light source unit is configured to increase as the detection frequency increases. As a result, even when the pulse width is reduced when the detection frequency of the detection unit is large (when the current is passed through the light source unit is short), the current value increases by increasing the voltage value of the power supplied to the light source unit. The speed to do can be increased. As a result, the peak current value of the power supplied to the light source unit can be set to a predetermined peak current value. And since it can suppress that the electric current value of electric power supplied to a light source part does not reach the state where it reaches the predetermined peak current value (peak current value large enough to acquire a photoacoustic wave signal). The photoacoustic wave signal can be suppressed from becoming small. As a result, it is possible to suppress the acoustic wave signal from becoming small even when a light emitting element such as a light emitting diode element is used for the light source unit and when the detection frequency of the detection unit is high.
　上記一の局面による光音響画像化装置において、好ましくは、光源駆動部は、検出部の検出周波数に基づいて、光源部から照射する光のパルス幅を設定するとともに、パルス幅が小さいほど、光源部に供給する電力の電圧値を大きくするように構成されている。このように構成すれば、パルス幅が小さいほど、光源部に供給する電力のピーク電流値が所定のピーク電流値に達するまでの時間が短くされるので、パルス幅を小さくする場合でも、確実に、光源部に供給する電力のピーク電流値を所定のピーク電流値にすることができる。 In the photoacoustic imaging apparatus according to the above aspect, preferably, the light source driving unit sets the pulse width of light emitted from the light source unit based on the detection frequency of the detection unit, and the smaller the pulse width, the light source The voltage value of the electric power supplied to the unit is increased. With this configuration, the smaller the pulse width, the shorter the time until the peak current value of the power supplied to the light source unit reaches the predetermined peak current value, so even when the pulse width is reduced, The peak current value of the power supplied to the light source unit can be set to a predetermined peak current value.
　この場合、好ましくは、光源駆動部は、互いに直列に接続されたｎ個の発光素子を含み、パルス幅をｔｗ、所定のピーク電流値をＩｏ、および、所定の比例定数をｋとして、以下の式（１）に表される電圧値Ｖに、光源部に供給する前記電力の電圧値を設定するように構成されている。
　Ｖ＝ｎ×１／ｋ×１／ｔｗ×Ｉｏ　・・・　（１）
　このように構成すれば、発光素子の数ｎ、パルス幅ｔｗ、および、所定のピーク電流値Ｉｏが変更された場合でも、上記の式（１）を用いることにより、光源部に供給する電力のピーク電流値が所定のピーク電流値Ｉｏになるための電圧値Ｖを容易に設定することができる。 In this case, preferably, the light source driving unit includes n light emitting elements connected in series with each other, the pulse width is tw, the predetermined peak current value is Io, and the predetermined proportionality constant is k. The voltage value of the electric power supplied to the light source unit is set to the voltage value V expressed by the equation (1).
V = n × 1 / k × 1 / tw × Io (1)
With this configuration, even when the number n of light emitting elements, the pulse width tw, and the predetermined peak current value Io are changed, by using the above equation (1), the power supplied to the light source unit The voltage value V for the peak current value to be the predetermined peak current value Io can be easily set.
　上記検出部の検出周波数に基づいて光源部から照射する光のパルス幅を設定する光音響画像化装置において、好ましくは、光源駆動部は、検出部が検出することが可能な音響波の最大周波数が大きいほど、パルス幅を小さく設定するように構成されている。ここで、被検体から発生する音響波は、被検体に照射されたパルス幅の逆数の値を有する周波数を最大周波数として、最大周波数以下の周波数を有する音響波として発生する。この点に着目して、本発明では、光源駆動部を、検出部が検出することが可能な音響波の最大周波数が大きいほど、パルス幅を小さく設定するように構成することにより、検出部の最大周波数が大きいほど、被検体から発生する音響波の最大周波数を大きくすることができる。その結果、検出部が検出することが可能な音響波の最大周波数と、被検体から発生する音響波の最大周波数とを略一致させることができるので、効率良く、音響波を発生させることができる。なお、本願明細書では、最大周波数とは、検出部が検出することが可能な音響波の周波数成分のピーク値（０ｄＢ）に対して、－６ｄＢの値となる周波数のうち、大きい周波数を最大周波数として記載している。 In the photoacoustic imaging apparatus that sets the pulse width of the light emitted from the light source unit based on the detection frequency of the detection unit, preferably, the light source drive unit is the maximum frequency of the acoustic wave that can be detected by the detection unit The larger the is, the smaller the pulse width is set. Here, 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. Focusing on this point, in the present invention, 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. As a result, since the maximum frequency of the acoustic wave that can be detected by the detection unit and the maximum frequency of the acoustic wave generated from the subject can be substantially matched, the acoustic wave can be generated efficiently. . In the specification of the present application, 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.
　上記一の局面による光音響画像化装置において、好ましくは、光源駆動部は、光源部の応答特性に基づいて、光源部に供給する電力のピーク電流値が所定のピーク電流値になるように、光源部に供給する電力の電圧値を設定するように構成されている。ここで、光源部では、電圧が印加された場合に、光源部の応答特性に応じて光源部に流れる電流の電流値の上昇する速度が変化する。この点に着目して、本発明では、光源駆動部を、光源部の応答特性に基づいて、光源部に供給する電力のピーク電流値が所定のピーク電流値になるように、光源部に供給する電力の電圧値を設定することにより、光源部に供給する電力のピーク電流値を上昇させる速度を適切に設定することができる。 In the photoacoustic imaging apparatus according to the above aspect, preferably, the light source driving unit is configured so that the peak current value of the power supplied to the light source unit becomes a predetermined peak current value based on the response characteristics of the light source unit. The voltage value of the electric power supplied to the light source unit is set. Here, in the light source unit, when a voltage is applied, the rate at which the current value of the current flowing through the light source unit increases according to the response characteristics of the light source unit. Focusing on this point, in the present invention, the light source driving unit is supplied to the light source unit so that the peak current value of the power supplied to the light source unit becomes a predetermined peak current value based on the response characteristics of the light source unit. By setting the voltage value of the power to be performed, it is possible to appropriately set the speed at which the peak current value of the power supplied to the light source unit is increased.
　この場合、好ましくは、光源部は、第１の波長の光を発する第１光源と、第１の波長とは異なる第２の波長の光を発する第２光源とを含み、光源駆動部は、第１光源の応答特性と第２光源の応答特性とに基づいて、第１光源に供給する電力のピーク電流値と第２光源に供給する電力のピーク電流値とが略等しいピーク電流値になるように、第１光源に供給する電力の第１電圧値および第２光源に供給する電力の第２電圧値をそれぞれ設定するように構成されている。ここで、一般的に、光源部の波長が異なる場合には、波長に応じて光源部の応答特性が異なる。このため、互いに波長が異なる第１光源および第２光源に、同じ電圧値を有する電力を供給した場合には、第１光源からのパルス光の光量（ピーク電流値）と第２光源からのパルス光の光量（ピーク電流値）とに違いが生じる。この場合、第１光源からのパルス光に起因する音響波の強度と、第２光源からのパルス光に起因する音響波の強度とを比較する際に、光量の違いを考慮した比較的複雑な補正をする必要があるので、光音響画像化装置の信号処理を複雑化すると考えられる。この点を考慮して、本発明では、上記のように構成することにより、第１光源に供給する電力のピーク電流値と第２光源に供給する電力のピーク電流値とを略等しくすることができるので、第１光源からのパルス光に起因する音響波の強度と、第２光源からのパルス光に起因する音響波の強度とを比較する場合に、比較的複雑な補正をする必要がないので、光音響画像化装置の信号処理が複雑化するのを抑制することができる。 In this case, preferably, the light source unit includes a first light source that emits light having a first wavelength and a second light source that emits light having a second wavelength different from the first wavelength, and the light source driving unit includes: Based on the response characteristics of the first light source and the response characteristics of the second light source, the peak current value of the power supplied to the first light source and the peak current value of the power supplied to the second light source are substantially equal to each other. As described above, the first voltage value of the power supplied to the first light source and the second voltage value of the power supplied to the second light source are respectively set. Here, generally, when the wavelength of the light source unit is different, the response characteristic of the light source unit is different depending on the wavelength. Therefore, when power having the same voltage value is supplied to the first light source and the second light source having different wavelengths, the light amount (peak current value) of the pulsed light from the first light source and the pulse from the second light source There is a difference between the amount of light (peak current value). In this case, when comparing the intensity of the acoustic wave caused by the pulsed light from the first light source and the intensity of the acoustic wave caused by the pulsed light from the second light source, a relatively complicated considering the difference in the amount of light. Since correction is necessary, it is considered that the signal processing of the photoacoustic imaging apparatus is complicated. Considering this point, in the present invention, by configuring as described above, the peak current value of the power supplied to the first light source and the peak current value of the power supplied to the second light source can be made substantially equal. Therefore, when comparing the intensity of the acoustic wave caused by the pulsed light from the first light source and the intensity of the acoustic wave caused by the pulsed light from the second light source, there is no need for relatively complicated correction. Therefore, it is possible to prevent the signal processing of the photoacoustic imaging apparatus from becoming complicated.
　上記一の局面による光音響画像化装置において、好ましくは、光源駆動部は、検出部の識別情報および光源部の識別情報の少なくとも一方と、光源部に供給する電力の電圧値との対応関係を表すテーブルに基づいて、光源部に供給する電力の電圧値を設定するように構成されている。このように構成すれば、テーブルを用いることにより、比較的複雑な計算式を用いて計算させる必要がない分、容易に、光源部に供給する電力の電圧値を設定することができる。 In the photoacoustic imaging apparatus according to the above aspect, the light source drive unit preferably has a correspondence relationship between at least one of the identification information of the detection unit and the identification information of the light source unit and the voltage value of the power supplied to the light source unit. Based on the table to represent, it is comprised so that the voltage value of the electric power supplied to a light source part may be set. If comprised in this way, the voltage value of the electric power supplied to a light source part can be set easily by the part which does not need to be calculated using a comparatively complicated calculation formula by using a table.
　上記一の局面による光音響画像化装置において、好ましくは、光源部は、発光ダイオード素子および半導体レーザ素子のうちの少なくとも一方を含む。このように構成すれば、固体レーザ素子（Ｑスイッチパルスレーザ光源）を用いる場合と異なり、光学系の振動による特性変動を抑制するための光学定盤や強固な筐体が必要にならないので、その分、光音響画像化装置の構造が大型化するのを抑制することができる。 In the photoacoustic imaging apparatus according to the above aspect, the light source section preferably includes at least one of a light emitting diode element and a semiconductor laser 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.
　本発明によれば、上記のように、発光ダイオード素子等の発光素子を用いる場合で、かつ、検出部の検出周波数が大きい場合でも、音響波信号が小さくなるのを抑制することができる。 According to the present invention, as described above, even when a light emitting element such as a light emitting diode element is used and the detection frequency of the detection unit is high, it is possible to suppress the acoustic wave signal from becoming small.
本発明の第１実施形態による光音響画像化装置の全体構成を示したブロック図である。1 is a block diagram illustrating an overall configuration of a photoacoustic imaging apparatus according to a first embodiment of the present invention. 本発明の第１実施形態による光音響画像化装置のパルス光の照射に関する構成を示したブロック図である。It is the block diagram which showed the structure regarding irradiation of the pulsed light of the photoacoustic imaging device by 1st Embodiment of this invention. 本発明の第１実施形態による検出部の検出周波数の特性を説明するための図である。It is a figure for demonstrating the characteristic of the detection frequency of the detection part by 1st Embodiment of this invention. 本発明の第１実施形態による光音響画像化装置のパルス光とピーク電流値との関係を説明するための図である。It is a figure for demonstrating the relationship between the pulsed light and peak current value of the photoacoustic imaging device by 1st Embodiment of this invention. 本発明の第１実施形態による光音響画像化装置の光源部に印加する電圧値とピーク電流値との関係を説明するための図である。It is a figure for demonstrating the relationship between the voltage value applied to the light source part of the photoacoustic imaging device by 1st Embodiment of this invention, and a peak current value. 本発明の第１実施形態による光音響画像化装置のパルス光を照射した場合の被検体から発生する音響波の周波数分布を説明するための図である。It is a figure for demonstrating the frequency distribution of the acoustic wave generate | occur | produced from the subject at the time of irradiating the pulsed light of the photoacoustic imaging device by 1st Embodiment of this invention. 本発明の第１実施形態による光音響画像化装置の光源部に印加する電圧値に対するピーク電流値の測定に関する実験結果を示す図である。It is a figure which shows the experimental result regarding the measurement of the peak current value with respect to the voltage value applied to the light source part of the photoacoustic imaging device by 1st Embodiment of this invention. 本発明の第２実施形態による光音響画像化装置の全体構成を示したブロック図である。It is the block diagram which showed the whole structure of the photoacoustic imaging device by 2nd Embodiment of this invention. 本発明の第２実施形態による光音響画像化装置の検出部の識別情報とパルス幅との対応関係を表すテーブルを示した図である。It is the figure which showed the table showing the correspondence of the identification information and pulse width of the detection part of the photoacoustic imaging device by 2nd Embodiment of this invention. 本発明の第２実施形態による光音響画像化装置の光源部の識別情報と電圧値との対応関係を表すテーブルを示した図である。It is the figure which showed the table showing the correspondence of the identification information and voltage value of the light source part of the photoacoustic imaging device by 2nd Embodiment of this invention. 本発明の第３実施形態による光音響画像化装置の全体構成を示したブロック図である。It is the block diagram which showed the whole structure of the photoacoustic imaging device by 3rd Embodiment of this invention. 本発明の第３実施形態による光音響画像化装置の光源部の識別情報と電圧値との対応関係を示すテーブルを示した図である。It is the figure which showed the table which shows the correspondence of the identification information and voltage value of the light source part of the photoacoustic imaging device by 3rd Embodiment of this invention. 本発明の第３実施形態による光音響画像化装置の第１光源部および第２光源部に印加する電圧値とピーク電流値との関係を説明するための図である。It is a figure for demonstrating the relationship between the voltage value and peak current value which are applied to the 1st light source part and 2nd light source part of the photoacoustic imaging device by 3rd Embodiment of this invention. 被検体の検出対象物の光吸収特性を説明するための図である。It is a figure for demonstrating the light absorption characteristic of the detection target object of a subject. 本発明の第１実施形態の変形例による光源部の構成を示すブロック図である。It is a block diagram which shows the structure of the light source part by the modification of 1st Embodiment of this invention.
　以下、本発明の実施形態を図面に基づいて説明する。 Hereinafter, embodiments of the present invention will be described with reference to the drawings.
　［第１実施形態］
　（光音響画像化装置の全体構成）
　図１～図６を参照して、本発明の第１実施形態による光音響画像化装置１００の全体構成について説明する。図１に示すように、光音響画像化装置１００は、被検体Ｐ（人体など）の内部の検出対象物（血液、臓器、および、穿刺針など）から音響波Ａを検出して、光音響波信号を画像化する機能を有する。 [First Embodiment]
(Overall configuration of photoacoustic imaging apparatus)
The overall configuration of the photoacoustic imaging apparatus 100 according to the first embodiment of the present invention will be described with reference to FIGS. As shown in FIG. 1, 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.
　本発明の第１実施形態による光音響画像化装置１００には、図１に示すように、プローブ本体部１と装置本体部２とが設けられている。また、光音響画像化装置１００には、プローブ本体部１と装置本体部２とを接続するケーブル３が設けられている。 The photoacoustic imaging apparatus 100 according to the first embodiment of the present invention 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.
　プローブ本体部１は、操作者により把持されながら被検体Ｐ（人体の体表など）の表面上に配置されるように構成されている。そして、プローブ本体部１には、光源部１１と検出部１２とが設けられている。 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.
　そして、光源部１１は、被検体Ｐに光を照射することが可能に構成されている。検出部１２は、光源部１１により被検体Ｐに光が照射されることに起因して被検体Ｐ内から発生する音響波Ａを検出するように構成されている。そして、検出部１２は、ケーブル３を介して、音響波Ａを光音響波信号として装置本体部２に伝達するように構成されている。 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.
　装置本体部２には、光源駆動部２１と、制御部２２と、画像化部２３と、画像表示部２４と、操作部２５とが設けられている。光源駆動部２１は、制御部２２からの指令に基づいて光源部１１に電力を供給して光源部１１を駆動させるように構成されている。制御部２２は、光音響画像化装置１００の各部の制御を行うように構成されている。画像化部２３は、プローブ本体部１により検出された光音響波信号を処理して画像化するように構成されている。画像表示部２４は、たとえば、液晶モニタからなり、画像化された光音響波信号を表示するように構成されている。操作部２５は、たとえば、キーボードなどからなり、操作者からの入力操作を受け付けるように構成されている。 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.
　（光音響画像化装置の各部の構成）
　〈パルス光の照射に関する構成〉
　光源部１１は、図２に示すように、複数の発光ダイオード素子１１ａを含む。発光ダイオード素子１１ａは、たとえば、複数（ｎ個）の発光ダイオード素子１１ａが互いに直列に接続された複数の発光素子群１１ｂとして構成されており、発光素子群１１ｂは、光源駆動部２１に対して、たとえば、３列並列に接続されている。なお、発光ダイオード素子１１ａは、特許請求の範囲の「発光素子」の一例である。 (Configuration of each part of the photoacoustic imaging apparatus)
<Configuration of pulsed light irradiation>
As illustrated in FIG. 2, the light source unit 11 includes a plurality of light emitting diode elements 11 a. For example, the light emitting diode element 11 a is configured as a plurality of light emitting element groups 11 b in which a plurality (n) of light emitting diode elements 11 a are connected in series, and the light emitting element group 11 b is connected to the light source driving unit 21. For example, three rows are connected in parallel. The light emitting diode element 11a is an example of the “light emitting element” in the claims.
　そして、光源部１１は、光源駆動部２１から電力が供給されることにより赤外域の波長（たとえば、６００ｎｍ以上１０００ｎｍ以下の波長であり、好ましくは、約８５０ｎｍの波長）を有するパルス光を放出することが可能に構成されている。そして、光源部１１は、複数の発光ダイオード素子１１ａから放出された光を被検体Ｐに照射するように構成されている。 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 light emitting diode elements 11a.
　そして、図１に示すように、光源部１１から被検体Ｐに照射されたパルス光は、被検体Ｐ内の検出対象物（たとえば、ヘモグロビン等）により吸収される。そして、検出対象物が、パルス光の照射強度（光量および吸収量）に応じて、膨張および収縮する（膨張した大きさから元の大きさに戻る）ことにより、検出対象物（被検体Ｐ）から音響波Ａが生じる。 And as shown in FIG. 1, 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). To generate an acoustic wave A.
　制御部２２は、光源駆動部２１に光トリガ信号を伝達するように構成されている。そして、光源駆動部２１は、光トリガ信号に応じて、光源部２１から光を照射させるように構成されている。また、制御部２２は、光トリガ信号に同期したサンプリングトリガ信号を画像化部２３に伝達するように構成されている。 The control unit 22 is configured to transmit a light trigger signal to the light source driving unit 21. And the light source drive part 21 is comprised so that light may be irradiated from the light source part 21 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.
　図２に示すように、光源駆動部２１は、駆動電源部２１ａとスイッチ部２１ｂ～２１ｄとを含む。 As shown in FIG. 2, the light source drive unit 21 includes a drive power supply unit 21a and switch units 21b to 21d.
　駆動電源部２１ａは、たとえば、ＤＣ／ＤＣコンバータ等からなり、外部電源（図示せず）から電力を取得するとともに、制御部２２から制御信号を取得するように構成されている。そして、駆動電源部２１ａは、取得した電力を、取得した制御信号に応じた電圧値Ｖを有する直流の電力に変換するように構成されている。そして、駆動電源部２１ａは、光源部１１の発光素子群１１ｂのアノード側に接続されており、発光ダイオード素子１１ａのアノード側に生成した電力を供給する（電圧値Ｖを印加する）ように構成されている。 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 the generated power (apply a voltage value V) to the anode side of the light emitting diode element 11a. Has been.
　スイッチ部２１ｂ～２１ｄは、それぞれの一方側は、光源部１１の発光ダイオード素子１１ａのカソード側に接続されており、それぞれの他方側は接地されている。そして、スイッチ部２１ｂ～２１ｄは、たとえば、ＦＥＴ（Ｆｉｅｌｄ　Ｅｆｆｅｃｔ　Ｔｒａｎｓｉｓｔｏｒ）を含み、それぞれ制御部２２からのパルス状の光トリガ信号に基づいて、オンとオフとを切り替え可能に構成されている。 The switch units 21b to 21d have one side connected to the cathode side of the light emitting diode element 11a of the light source unit 11, and the other side 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.
　そして、スイッチ部２１ｂ～２１ｄがオンした場合には、発光ダイオード素子１１ａのカソード側の電圧値が低下する（接地される）ことにより、発光ダイオード素子１１ａのアノード側とカソード側とに電位差（略電圧値Ｖ）が生じて、発光ダイオード素子１１ａに電流が流れるように構成されている。すなわち、スイッチ部２１ｂ～２１ｄがオンする時間が光源部１１から照射されるパルス光のパルス幅ｔｗの大きさに対応して、発光ダイオード素子１１ａに流れる電流値の大きさが光源部１１から照射されるパルス光の光量の大きさに対応する。 When the switch units 21b to 21d are turned on, the voltage value on the cathode side of the light emitting diode element 11a is lowered (grounded), so that a potential difference (approximately) between the anode side and the cathode side of the light emitting diode element 11a. A voltage value V) is generated, and a current flows through the light emitting diode element 11a. That is, the magnitude of the current value flowing through the light emitting diode element 11a is emitted from the light source unit 11 corresponding to the magnitude of the pulse width tw of the pulsed light emitted from the light source unit 11 when the switch units 21b to 21d are turned on. This corresponds to the magnitude of the amount of pulsed light to be generated.
　〈音響波の検出に関する構成〉
　検出部１２は、圧電素子（たとえば、チタン酸ジルコン酸鉛（ＰＺＴ））などにより構成されている。そして、検出部１２は、上記した音響波Ａを取得した場合には、振動して電圧（信号）を生じるように構成されている。そして、検出部１２は、図１に示すように、光音響波信号を装置本体部２に伝達するように構成されている。 <Configuration for acoustic wave detection>
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.
　ここで、図３に示すように、検出部１２が検出することが可能な最大周波数ｆｍａｘは、検出部１２が検出することが可能な音響波Ａの周波数特性（検出周波数の特性）から決定される。図３に示す例の場合、検出部１２が検出することが可能な最大周波数ｆｍａｘは、ピーク値（０ｄＢ）を基準として、６ｄＢ小さい（－６ｄＢとなる）周波数（７．５ＭＨｚおよび２．５ＭＨｚ）のうちの高い周波数である７．５ＭＨｚである。なお、本願明細書では、上記のように、最大周波数ｆｍａｘを、検出部１２が検出することが可能な音響波Ａの周波数成分のピーク値（０ｄＢ）に対して、－６ｄＢの値となる周波数のうち、大きい周波数を最大周波数ｆｍａｘとして記載している。 Here, as shown in FIG. 3, 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 In the case of the example shown in FIG. 3, the maximum frequency fmax that can be detected by the detection unit 12 is a frequency (7.5 MHz and 2.5 MHz) that is 6 dB smaller (becomes −6 dB) with respect to the peak value (0 dB). The higher frequency is 7.5 MHz. In the present specification, as described above, 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. Among these, a large frequency is described as the maximum frequency fmax.
　ここで、検出部１２は、検出することが可能な最大周波数ｆｍａｘが、２０ＭＨｚ以下になるように構成されている。一般的に、音響波Ａの周波数は大きくなる程、分解能は大きくなる一方、音響波Ａが被検体Ｐの内部で伝搬する際の減衰率は大きくなる。たとえば、被検体Ｐ（たとえば、生体）から２０ＭＨｚよりも大きな音響波Ａが発生した場合に、表層部分よりも深い部分から発生した２０ＭＨｚよりも大きな音響波Ａは、検出部１２に到達することが困難になる。すなわち、検出部１２が検出することが可能な最大周波数ｆｍａｘを２０ＭＨｚよりも大きくした場合は、検出部１２が検出することが可能な最大周波数ｆｍａｘを２０ＭＨｚとした場合と実質的に検出される音響波Ａの周波数は同等となる。したがって、検出部１２の最大周波数ｆｍａｘが２０ＭＨｚ以下になるように、検出部１２を構成するのが好ましい。 Here, the detection unit 12 is configured such that the maximum frequency fmax that can be detected is 20 MHz or less. In general, as the frequency of the acoustic wave A increases, the resolution increases, while the attenuation rate when the acoustic wave A propagates inside the subject P increases. For example, when an 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. That is, when 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.
　また、検出部１２が検出することが可能な最大周波数ｆｍａｘは、１ＭＨｚ以上になるように構成されている。一般的に、音響波Ａの周波数が小さい程、音響波Ａが被検体Ｐの内部を伝搬することが可能な距離（深度）は大きくなる一方、分解能は小さくなる。たとえば、１ＭＨｚの音響波Ａを用いて画像化する場合、分解能は、約１．５ｍｍとなる。一般的に、音響波Ａの画像を診断に用いる場合には、分解能が１．５ｍｍ以下であることが望ましい。したがって、検出部１２の最大周波数ｆｍａｘが１ＭＨｚ以上になるように構成することにより、光音響画像化装置１００を用いた診断が困難になるのを抑制することが可能になる。 Further, the maximum frequency fmax that can be detected by the detection unit 12 is configured to be 1 MHz or more. In general, 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. For example, when imaging using 1 MHz acoustic wave A, the resolution is about 1.5 mm. Generally, when an image of acoustic wave A is used for diagnosis, it is desirable that 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.
　〈パルス幅の設定および光源部に供給する電力の電圧値の設定に関する構成〉
　図４は、光源部１１に印加する電圧値Ｖを一定にした場合の光源部１１に流れる電流の波形について図示している。たとえば、制御部２２は、期間τ１の間（時点ｔ１からｔ２までの期間）、光トリガ信号をスイッチ部２１ｂ～２１ｄに伝達した場合には、光源部１１から照射される光のパルス幅ｔｗは、ｔｗ１となる（たとえば、１００ｎｓとする）。なお、本願明細書では、パルス光のパルス幅ｔｗを、発光ダイオード素子１１ａに流れる電流値の半値全幅の時間幅として記載している。 <Configuration related to setting of pulse width and voltage value of power supplied to light source unit>
FIG. 4 illustrates a waveform of a current flowing through the light source unit 11 when the voltage value V applied to the light source unit 11 is constant. For example, when the control unit 22 transmits the light trigger signal to the switch units 21b to 21d during the period τ1 (the period from the time point t1 to t2), the pulse width tw of the light emitted from the light source unit 11 is Tw1 (for example, 100 ns). In the present specification, the pulse width tw of the pulsed light is described as the time width of the full width at half maximum of the current value flowing through the light emitting diode element 11a.
　この場合、光源部１１（発光ダイオード素子１１ａ）に流れる電流値は、時点ｔ１からｔ２にかけて徐々に大きくなり、時点ｔ２において、発光ダイオード素子１１ａに流れる電流値の最大値であるピーク電流値ＩｐがＩ１となる（たとえば、１５Ａとする）。そして、発光ダイオード素子１１ａに流れる電流値は、時点ｔ２の後は徐々に小さくなり、時点ｔ３で略零になる。すなわち、発光ダイオード素子１１ａに流れる電流値の波形（パルス光の波形）は、略三角波形状を有するように、光源駆動部２１により電力が供給される。 In this case, the current value flowing through the light source unit 11 (light-emitting diode element 11a) gradually increases from time t1 to time t2, and the peak current value Ip, which is the maximum value of the current value flowing through the light-emitting diode element 11a, is increased at time t2. I1 (for example, 15A). The value of the current flowing through the light emitting diode element 11a gradually decreases after time t2, and becomes substantially zero at time t3. That is, power is supplied from the light source driving unit 21 so that the waveform of the current value flowing through the light emitting diode element 11a (the waveform of the pulsed light) has a substantially triangular wave shape.
　また、制御部２２は、期間τ１よりも長い期間τ２の間（時点ｔ１からｔ４までの期間）、光トリガ信号をスイッチ部２１ｂ～２１ｄに伝達した場合には、光源部１１から照射される光のパルス幅ｔｗは、ｔｗ２となる（たとえば、５００ｎｓとする）。この場合、光源部１１（発光ダイオード素子１１ａ）に流れる電流値は、時点ｔ１から時点ｔ４にかけて徐々に大きくなり、時点ｔ４において、ピーク電流値Ｉｐが電流値Ｉ１よりも大きなＩ２となる（たとえば、７５Ａとする）。そして、発光ダイオード素子１１ａに流れる電流値は、時点ｔ４の後は徐々に小さくなり、時点ｔ５で略零になる。したがって、光源駆動部２１の駆動電源部２１ａの電圧値Ｖを一定にして、光源部１１に印加する電圧値Ｖを一定にした場合には、光源部１１に流れる電流のピーク電流値Ｉｐは、パルス幅ｔｗが大きい程、大きく、パルス幅ｔｗが小さい程、小さくなる。 In addition, the control unit 22 transmits light emitted from the light source unit 11 when the optical trigger signal is transmitted to the switch units 21b to 21d during the period τ2 longer than the period τ1 (period from the time point t1 to t4). The pulse width tw becomes tw2 (for example, 500 ns). In this case, the current value flowing through the light source unit 11 (light emitting diode element 11a) gradually increases from time t1 to time t4, and at time t4, the peak current value Ip becomes I2 larger than the current value I1 (for example, 75A). Then, the value of the current flowing through the light emitting diode element 11a gradually decreases after time t4 and becomes substantially zero at time t5. Therefore, when the voltage value V of the driving power supply unit 21a of the light source driving unit 21 is made constant and the voltage value V applied to the light source unit 11 is made constant, the peak current value Ip of the current flowing through the light source unit 11 is The larger the pulse width tw, the larger, and the smaller the pulse width tw, the smaller.
　図５は、光源部１１に印加する電圧値Ｖを変化させた場合の光源部１１に流れる電流の波形について図示している。具体的には、光源部１１に電圧を印加する期間を一定（期間τ３（時点ｔ１１からｔ１３まで）にした状態で、光源部１１に印加する電圧値Ｖを電圧値Ｖ１、Ｖ２、および、Ｖ３とした場合のそれぞれの電流値の波形を、図４に示している。なお、電圧値Ｖ１、Ｖ２、および、Ｖ３は、Ｖ１＞Ｖ２＞Ｖ３の関係があるものとする。 FIG. 5 illustrates a waveform of a current flowing through the light source unit 11 when the voltage value V applied to the light source unit 11 is changed. Specifically, the voltage value V applied to the light source unit 11 is set to the voltage values V1, V2, and V3 in a state where the period during which the voltage is applied to the light source unit 11 is constant (period τ3 (from time t11 to t13)). 4 shows the waveforms of the respective current values in the case where the voltage values V1, V2, and V3 are assumed to have a relationship of V1> V2> V3.
　この場合、光源部１１に流れる電流のピーク電流値Ｉｐは、電圧値Ｖ１の場合、電流値Ｉ３となり、電圧値Ｖ２の場合、電流値Ｉ４となり、電圧値Ｖ３の場合、電流値Ｉ５となる。なお、Ｉ３＞Ｉ４＞Ｉ５の関係を有する。 In this case, the peak current value Ip of the current flowing through the light source unit 11 is the current value I3 in the case of the voltage value V1, the current value I4 in the case of the voltage value V2, and the current value I5 in the case of the voltage value V3. Note that the relationship of I3> I4> I5 is satisfied.
　ここで、電流値Ｉ４を設定ピーク電流値Ｉｏとすると、光源部１１に供給する電力の電圧値Ｖが大きい程、光源部１１に供給する電力のピーク電流値Ｉｐが設定ピーク電流値Ｉｏに達するまでの時間が短くなり、光源部１１に供給する電力の電圧値Ｖが小さい程、光源部１１に供給する電力のピーク電流値Ｉｐが設定ピーク電流値Ｉｏに達するまでの時間が長くなる。たとえば、電圧値Ｖ１の場合には、時点ｔ１３より前の時点ｔ１２に、発光ダイオード素子１１ａに流れる電流値が設定ピーク電流値Ｉｏに到達する。また、電圧値Ｖ２の場合には、時点ｔ１３に、発光ダイオード素子１１ａに流れる電流値が設定ピーク電流値Ｉｏに到達する。電圧値Ｖ３の場合には、時点ｔ１３より後に、発光ダイオード素子１１ａに流れる電流値が設定ピーク電流値Ｉｏに到達する。 Here, assuming that the current value I4 is the set peak current value Io, the peak current value Ip of power supplied to the light source unit 11 reaches the set peak current value Io as the voltage value V of power supplied to the light source unit 11 increases. The time until the peak current value Ip of the power supplied to the light source unit 11 reaches the set peak current value Io becomes longer as the voltage value V of the power supplied to the light source unit 11 is smaller. For example, in the case of the voltage value V1, the current value flowing through the light emitting diode element 11a reaches the set peak current value Io at time t12 prior to time t13. In the case of the voltage value V2, the current value flowing through the light emitting diode element 11a reaches the set peak current value Io at time t13. In the case of the voltage value V3, the current value flowing through the light emitting diode element 11a reaches the set peak current value Io after time t13.
　すなわち、光源部１１に供給する電力の電圧値Ｖが大きい程、光源部１１に供給する電力の電流値が上昇する速度（単位時間あたりの電流値の上昇値）が大きくなり、光源部１１に供給する電力の電圧値Ｖが小さい程、光源部１１に供給する電力の電流値が上昇する速度が小さくなる。 That is, as the voltage value V of the power supplied to the light source unit 11 increases, the speed at which the current value of the power supplied to the light source unit 11 increases (the increase value of the current value per unit time) increases. The speed at which the current value of the power supplied to the light source unit 11 increases as the voltage value V of the supplied power decreases.
　ここで、第１実施形態では、光源駆動部２１は、光源部１１に供給する電力のピーク電流値Ｉｐが設定ピーク電流値Ｉｏになるように、検出部１２の検出周波数（検出部１２が検出することが可能な最大周波数ｆｍａｘ）が大きいほど、光源部１１に供給する電力の電圧値Ｖを大きくするように構成されている。以下、具体的に説明する。 Here, in the first embodiment, the light source driving unit 21 detects the detection frequency of the detection unit 12 (detected by the detection unit 12 so that the peak current value Ip of the power supplied to the light source unit 11 becomes the set peak current value Io. The voltage value V of the power supplied to the light source unit 11 is increased as the maximum frequency fmax) that can be increased is increased. This will be specifically described below.
　第１実施形態では、光源駆動部２１（制御部２２）により設定ピーク電流値Ｉｏが予め設定されている。設定ピーク電流値Ｉｏは、設定ピーク電流値Ｉｏが光源部１１に流れることにより生成されたパルス光が被検体Ｐに照射された場合に、被検体Ｐから十分な大きさの音響波Ａを生成させることが可能な値に設定されている。たとえば、図５に示すように、設定ピーク電流値Ｉｏは、Ｉ４として設定されている。 In the first embodiment, the set peak current value Io is set in advance by the light source driving unit 21 (control unit 22). The set peak current value Io generates a sufficiently large acoustic wave A from the subject P when the subject P is irradiated with pulsed light generated by the set peak current value Io flowing to the light source unit 11. It is set to a possible value. For example, as shown in FIG. 5, the set peak current value Io is set as I4.
　そして、第１実施形態では、光源駆動部２１（制御部２２）は、検出部１２の検出周波数（検出部１２が検出することが可能な最大周波数ｆｍａｘ）に基づいて、光源部１１から照射する光のパルス幅ｔｗを設定するように構成されている。 And in 1st Embodiment, the light source drive part 21 (control part 22) irradiates from the light source part 11 based on the detection frequency (maximum frequency fmax which the detection part 12 can detect) of the detection part 12. FIG. The light pulse width tw is set.
　具体的には、光源部１１のパルス幅ｔｗは、検出部１２が検出することが可能な音響波Ａの最大周波数をｆｍａｘとした場合に、光源駆動部２１（制御部２２）により発光ダイオード素子１１ａに電圧が印加される時間の幅（光トリガ信号のパルス幅）が調整されることにより、パルス光のパルス幅ｔｗを、下記の式（２）に表されるパルス幅ｔｗに設定するように構成されている。
　０．５／ｆｍａｘ≦ｔｗ≦１／ｆｍａｘ　・・・　（２） Specifically, the pulse width tw of the light source unit 11 is a light emitting diode element by the light source driving unit 21 (control unit 22) when the maximum frequency of the acoustic wave A that can be detected by the detection unit 12 is fmax. The pulse width tw of the pulsed light is set to the pulse width tw represented by the following expression (2) by adjusting the width of time during which voltage is applied to 11a (pulse width of the optical trigger signal). It is configured.
0.5 / fmax ≦ tw ≦ 1 / fmax (2)
　たとえば、検出部１２の最大周波数ｆｍａｘが７．５ＭＨｚ（図３参照）であるとすると、制御部２２は、パルス幅ｔｗを、０．５／７．５ＭＨｚ≦ｔｗ≦１／７．５ＭＨｚに設定する。すなわち、パルス幅ｔｗは、約６７ｎｓ以上約１３３ｎｓ以下の範囲内に設定される。そして、たとえば、制御部２２により、パルス幅ｔｗを１００ｎｓに設定したとすると、光源部１１により照射された光に起因して発生する音響波Ａの周波数分布は、図６に示すように、検出部１２が検出することが可能な音響波Ａの周波数特性（図３参照）に対応するような分布となる。 For example, if the maximum frequency fmax of the detection unit 12 is 7.5 MHz (see FIG. 3), the control unit 22 sets the pulse width tw to 0.5 / 7.5 MHz ≦ tw ≦ 1 / 7.5 MHz. To do. That is, the pulse width tw is set within a range of about 67 ns to about 133 ns. For example, when the control unit 22 sets the pulse width tw to 100 ns, the frequency distribution of the acoustic wave A generated due to the light irradiated by the light source unit 11 is detected as shown in FIG. The distribution corresponds to the frequency characteristics (see FIG. 3) of the acoustic wave A that can be detected by the unit 12.
　そして、第１実施形態では、光源駆動部２１（制御部２２）は、パルス幅ｔｗが小さいほど、光源部１１に供給する電力の電圧値Ｖを大きくするように構成されている。すなわち、光源駆動部２１（制御部２２）は、検出部１２の検出周波数（検出部１２が検出することが可能な最大周波数ｆｍａｘ）が大きいほど、光源部１１に供給する電力の電圧値Ｖを大きくするように構成されている。詳細には、光源駆動部２１は、互いに直列に接続されたｎ個の発光素子を含み、パルス幅をｔｗ、設定ピーク電流値をＩｏ、および、所定の比例定数をｋとして、以下の式（３）に表される電圧値Ｖに、光源部１１に供給する電力の電圧値Ｖを設定するように構成されている。
　Ｖ＝ｎ×１／ｋ×１／ｔｗ×Ｉｏ　・・・　（３） And in 1st Embodiment, the light source drive part 21 (control part 22) is comprised so that the voltage value V of the electric power supplied to the light source part 11 may become large, so that the pulse width tw is small. That is, the light source drive unit 21 (control unit 22) increases the voltage value V of the power supplied to the light source unit 11 as the detection frequency of the detection unit 12 (the maximum frequency fmax that can be detected by the detection unit 12) increases. It is configured to be large. More specifically, the light source driving unit 21 includes n light emitting elements connected in series with each other, the pulse width is tw, the set peak current value is Io, and the predetermined proportionality constant is k. The voltage value V of the electric power supplied to the light source unit 11 is set to the voltage value V represented in 3).
V = n × 1 / k × 1 / tw × Io (3)
　たとえば、図５に示すように、設定ピーク電流値ＩｏがＩ４、パルス幅ｔｗが１００ｎｓ（光トリガ信号のパルス幅τ３）の場合、電圧値Ｖは、Ｖ２として設定される。これにより、光源駆動部２１は、所望の設定ピーク電流値Ｉｏとパルス幅ｔｗとを有するパルス光を生成することが可能になる。 For example, as shown in FIG. 5, when the set peak current value Io is I4 and the pulse width tw is 100 ns (pulse width τ3 of the optical trigger signal), the voltage value V is set as V2. Thereby, the light source driving unit 21 can generate pulsed light having a desired set peak current value Io and a pulse width tw.
　また、たとえば、操作者による操作部２５の操作に基づいて、制御部２２（光源駆動部２１）により、パルス幅ｔｗが、１００ｎｓよりも大きく（光トリガ信号のパルス幅τ４（＞τ３））設定された場合にも、上記の式（３）を用いて同様に、電圧値Ｖが電圧値Ｖ４（＜Ｖ２）に設定される。 For example, based on the operation of the operation unit 25 by the operator, the control unit 22 (light source driving unit 21) sets the pulse width tw to be larger than 100 ns (pulse width τ4 (> τ3) of the optical trigger signal). In this case, the voltage value V is similarly set to the voltage value V4 (<V2) using the above equation (3).
　（光源部に印加する電圧値とピーク電流値との関係に関する実験結果）
　次に、図７を参照して、第１実施形態による光音響画像化装置１００における、光源部１１に印加する電圧値Ｖと、光源部１１に流れる電流のピーク電流値Ｉｐとの関係に関する実験結果について説明する。この実験では、発光ダイオード素子１１ａの個数ｎを１、パルス幅ｔｗを１００ｎｓとして、光源部１１に印加する電圧値Ｖを変化させて、ピーク電流値Ｉｐを測定する実験を行った。 (Experimental results on the relationship between the voltage value applied to the light source and the peak current value)
Next, with reference to FIG. 7, in the photoacoustic imaging apparatus 100 according to the first embodiment, an experiment relating to the relationship between the voltage value V applied to the light source unit 11 and the peak current value Ip of the current flowing through the light source unit 11. The results will be described. In this experiment, the number n of light emitting diode elements 11a was set to 1, the pulse width tw was set to 100 ns, and the voltage value V applied to the light source unit 11 was changed to measure the peak current value Ip.
　測定の結果、光源部１１に印加する電圧値Ｖを、７Ｖとした場合、ピーク電流値Ｉｐは、８Ａとなった。また、電圧値Ｖを、１３Ｖとした場合、ピーク電流値Ｉｐは、１５Ａとなった。また、電圧値Ｖを、２０Ｖとした場合、ピーク電流値Ｉｐは、２２Ａとなった。また、電圧値Ｖを、２７Ｖとした場合、ピーク電流値Ｉｐは、３０Ａとなった。また、電圧値Ｖを、３４Ｖとした場合、ピーク電流値Ｉｐは、３９Ａとなった。また、電圧値Ｖを、４１Ｖとした場合、ピーク電流値Ｉｐは、４６Ａとなった。また、電圧値Ｖを、４８Ｖとした場合、ピーク電流値Ｉｐは、５２Ａとなった。また、電圧値Ｖを、５３Ｖとした場合、ピーク電流値Ｉｐは、６０Ａとなった。また、電圧値Ｖを、５９Ｖとした場合、ピーク電流値Ｉｐは、６６Ａとなった。 As a result of the measurement, when the voltage value V applied to the light source unit 11 is 7V, the peak current value Ip is 8A. Further, when the voltage value V was 13 V, the peak current value Ip was 15A. Further, when the voltage value V was 20 V, the peak current value Ip was 22A. Further, when the voltage value V was 27 V, the peak current value Ip was 30 A. Further, when the voltage value V was 34V, the peak current value Ip was 39A. Further, when the voltage value V was 41 V, the peak current value Ip was 46 A. Further, when the voltage value V was 48V, the peak current value Ip was 52A. Further, when the voltage value V was 53 V, the peak current value Ip was 60A. Further, when the voltage value V was 59 V, the peak current value Ip was 66 A.
　以上の結果から、光源部１１に印加する電圧値Ｖと、光源部１１に流れる電流のピーク電流値Ｉｐとは、以下の式（４）に示すような比例関係を有することが判明した。
　Ｉｐ＝ｋ×ｔｗ／ｎ×Ｖ　・・・　（４） From the above results, it has been found that the voltage value V applied to the light source unit 11 and the peak current value Ip of the current flowing through the light source unit 11 have a proportional relationship as shown in the following formula (4).
Ip = k × tw / n × V (4)
　これにより、上記の式（４）のピーク電流値Ｉｐを設定ピーク電流値Ｉｏとして、上記の式（４）を変形すれば、上記の（３）を導くことが可能であることが判明した。 Thus, it has been found that if the above formula (4) is modified with the peak current value Ip of the above formula (4) as the set peak current value Io, the above (3) can be derived.
　第１実施形態では、以下のような効果を得ることができる。 In the first embodiment, the following effects can be obtained.
　第１実施形態では、上記のように、光源駆動部２１を、光源部１１に供給する電力のピーク電流値Ｉｐが設定ピーク電流値Ｉｏになるように、検出部１２の検出周波数（の最大周波数ｆｍａｘ）が大きいほど、光源部１１に供給する電力の電圧値Ｖを大きくするように構成する。これにより、検出部１２の検出周波数が大きい場合にパルス幅ｔｗを小さくする場合（光源部１１に電流を流す時間が短い場合）でも、光源部１１に供給する電力の電圧値Ｖを大きくすることにより電流値が上昇する速度を大きくすることができる。この結果、光源部１１に供給する電力のピーク電流値Ｉｐを設定ピーク電流値Ｉｏにすることができる。そして、光源部１１に供給する電力の電流値が設定ピーク電流値Ｉｏ（光音響波信号を取得するために十分な大きさのピーク電流値）に達しない状態になるのを抑制することができるので、光音響波信号が小さくなるのを抑制することができる。その結果、発光ダイオード素子１１ａを用いる場合で、かつ、検出部１２の検出周波数が大きい場合にも、音響波信号が小さくなるのを抑制することができる。 In the first embodiment, as described above, the detection frequency of the detection unit 12 (the maximum frequency thereof) is set so that the peak current value Ip of the power supplied to the light source unit 11 is the set peak current value Io. The voltage value V of the electric power supplied to the light source unit 11 is increased as fmax) increases. Thereby, even when the pulse width tw is reduced when the detection frequency of the detection unit 12 is large (when the current is passed through the light source unit 11 is short), the voltage value V of the power supplied to the light source unit 11 is increased. As a result, the speed at which the current value increases can be increased. As a result, the peak current value Ip of the power supplied to the light source unit 11 can be set to the set peak current value Io. And it can suppress that the electric current value of the electric power supplied to the light source part 11 will not be in the state which does not reach setting peak electric current value Io (peak electric current value large enough to acquire a photoacoustic wave signal). Therefore, it can suppress that a photoacoustic wave signal becomes small. As a result, when the light emitting diode element 11a is used and the detection frequency of the detection unit 12 is high, it is possible to suppress the acoustic wave signal from becoming small.
　また、第１実施形態では、上記のように、光源駆動部２１を、検出部１２の検出周波数に基づいて、光源部１１から照射する光のパルス幅ｔｗを設定するとともに、パルス幅ｔｗが小さいほど、光源部１１に供給する電力の電圧値Ｖを大きくするように構成する。これにより、パルス幅ｔｗが小さいほど、光源部１１に供給する電力のピーク電流値Ｉｐが設定ピーク電流値Ｉｏに達するまでの時間を短くすることができるので、パルス幅ｔｗを小さくする場合でも、確実に、光源部１１に供給する電力のピーク電流値Ｉｐを設定ピーク電流値Ｉｏにすることができる。 In the first embodiment, as described above, the light source driving unit 21 sets the pulse width tw of light emitted from the light source unit 11 based on the detection frequency of the detection unit 12, and the pulse width tw is small. The configuration is such that the voltage value V of the power supplied to the light source unit 11 is increased. Thereby, as the pulse width tw is smaller, the time until the peak current value Ip of the power supplied to the light source unit 11 reaches the set peak current value Io can be shortened. Therefore, even when the pulse width tw is decreased, The peak current value Ip of the power supplied to the light source unit 11 can be reliably set to the set peak current value Io.
　また、第１実施形態では、上記のように、光源駆動部２１を、互いに直列に接続されたｎ個の発光ダイオード素子１１ａを含み、パルス幅をｔｗ、設定ピーク電流値をＩｏ、および、所定の比例定数をｋとして、上記の式（３）に表される電圧値Ｖに、光源部１１に供給する電力の電圧値を設定するように構成する。これにより、発光ダイオード素子１１ａの数、パルス幅ｔｗ、および、設定ピーク電流値Ｉｏが変更された場合でも、上記の式（３）を用いることにより、光源部１１に供給する電力のピーク電流値Ｉｐが設定ピーク電流値Ｉｏになるための電圧値Ｖを容易に設定することができる。 In the first embodiment, as described above, the light source drive unit 21 includes n light emitting diode elements 11a connected in series with each other, the pulse width is tw, the set peak current value is Io, and the predetermined value is set. Is set to the voltage value V of the electric power supplied to the light source unit 11 to the voltage value V expressed by the above equation (3). Thereby, even when the number of light emitting diode elements 11a, the pulse width tw, and the set peak current value Io are changed, the peak current value of the power supplied to the light source unit 11 is obtained by using the above equation (3). The voltage value V for allowing Ip to become the set peak current value Io can be easily set.
　また、第１実施形態では、上記のように、光源駆動部２１を、検出部１２が検出することが可能な音響波の最大周波数ｆｍａｘが大きいほど、パルス幅ｔｗを小さく設定するように構成する。ここで、被検体１２から発生する音響波Ａは、被検体Ｐに照射されたパルス幅ｔｗの逆数の値を有する周波数を最大周波数として、最大周波数以下の周波数を有する音響波Ａとして発生（図６参照）する。この点に着目して、第１実施形態では、光源駆動部２１を、検出部１２が検出することが可能な音響波の最大周波数ｆｍａｘが大きいほど、パルス幅ｔｗを小さく設定するように構成することにより、検出部１２の最大周波数ｆｍａｘが大きいほど、被検体Ｐから発生する音響波Ａの最大周波数を大きくすることができる。その結果、検出部１２が検出することが可能な音響波の最大周波数ｆｍａｘと、被検体Ｐから発生する音響波Ａの最大周波数とを略一致させることができるので、効率良く、音響波Ａを発生させることができる。 In the first embodiment, as described above, the light source driving unit 21 is configured to set the pulse width tw to be smaller as the maximum acoustic wave frequency fmax that can be detected by the detection unit 12 is larger. . Here, the acoustic wave A generated from the subject 12 is generated as an acoustic wave A having a frequency equal to or lower than the maximum frequency with a frequency having a reciprocal value of the pulse width tw irradiated to the subject P as a maximum frequency (FIG. 6). Focusing on this point, in the first embodiment, the light source drive unit 21 is configured to set the pulse width tw to be smaller as the maximum frequency fmax of the acoustic wave that can be detected by the detection unit 12 is larger. Accordingly, the maximum frequency of the acoustic wave A generated from the subject P can be increased as the maximum frequency fmax of the detection unit 12 is increased. As a result, since the maximum frequency fmax of the acoustic wave that can be detected by the detection unit 12 and the maximum frequency of the acoustic wave A generated from the subject P can be substantially matched, the acoustic wave A can be efficiently and efficiently transmitted. Can be generated.
　また、第１実施形態では、上記のように、光源部１１に、発光ダイオード素子１１ａを設ける。これにより、固体レーザ素子（Ｑスイッチパルスレーザ光源）を用いる場合と異なり、光学系の振動による特性変動を抑制するための光学定盤や強固な筐体が必要にならないので、その分、光音響画像化装置１００の構造が大型化するのを抑制することができる。 Further, in the first embodiment, as described above, the light source diode 11 is provided in the light source unit 11. As a result, unlike the case of using a solid-state laser 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.
　［第２実施形態］
　次に、図８～図１０を参照して、第２実施形態による光音響画像化装置２００の構成について説明する。第２実施形態では、検出部２１２の検出周波数の特性のみならず、光源部２１１の応答特性に基づいて、光源部２１１に供給する電力のピーク電流値Ｉｐが設定ピーク電流値Ｉｏになるように、光源部２１１に供給する電力の電圧値Ｖを設定するように構成されている。なお、上記第１実施形態と同一の構成については、同じ符号を付してその説明を省略する。 [Second Embodiment]
Next, the configuration of the photoacoustic imaging apparatus 200 according to the second embodiment will be described with reference to FIGS. In the second embodiment, based on not only the detection frequency characteristic of the detection unit 212 but also the response characteristic of the light source unit 211, the peak current value Ip of the power supplied to the light source unit 211 is set to the set peak current value Io. The voltage value V of the power supplied to the light source unit 211 is set. In addition, about the structure same as the said 1st Embodiment, the same code | symbol is attached | subjected and the description is abbreviate | omitted.
　（第２実施形態による光音響画像化装置の構成）
　図８に示すように、第２実施形態による光音響画像化装置２００には、プローブ本体部２０１と、装置本体部２０２とが設けられている。プローブ本体部２０１は、光源部２１１と検出部２１２とを含む。また、装置本体部２０２は、光源駆動部２２１と、制御部２２２と、記憶部２２５とを含む。 (Configuration of Photoacoustic Imaging Apparatus According to Second Embodiment)
As shown in FIG. 8, the photoacoustic imaging apparatus 200 according to the second embodiment includes a probe main body 201 and an apparatus main body 202. The probe main body unit 201 includes a light source unit 211 and a detection unit 212. In addition, the apparatus main body 202 includes a light source driving unit 221, a control unit 222, and a storage unit 225.
　プローブ本体部２０１は、ケーブル３に対して、脱着可能に構成されており、プローブ本体部２０１を他の種類のプローブ本体部２０１に交換することが可能に構成されている。 The probe main body 201 is configured to be detachable from the cable 3, and is configured to be able to replace the probe main body 201 with another type of probe main body 201.
　光源部２１１は、複数の発光ダイオード素子１１ａを含む。また、光源部２１１には、予め識別情報（Ｉｄｅｎｔｉｆｉｃａｔｉｏｎ）２１１ｂが格納されている。そして、光源部２１１は、プローブ本体部２０１に対して、脱着可能に構成されており、光源部２１１を他の種類の（応答特性が異なる）光源部２１１に交換することが可能に構成されている。 The light source unit 211 includes a plurality of light emitting diode elements 11a. The light source unit 211 stores identification information (identification) 211b in advance. The light source unit 211 is configured to be detachable from the probe main body unit 201, and is configured to be able to replace the light source unit 211 with another type of light source unit 211 (having different response characteristics). Yes.
　検出部２１２には、予め識別情報２１２ａが格納されている。そして、検出部２１２は、光源部２１１と同様に、プローブ本体部２０１に対して、脱着可能に構成されており、検出部２１２を他の種類の（最大周波数ｆｍａｘが異なる）検出部２１２に交換することが可能に構成されている。 In the detection unit 212, identification information 212a is stored in advance. Similarly to the light source unit 211, the detection unit 212 is configured to be detachable from the probe main body unit 201, and the detection unit 212 is replaced with another type of detection unit 212 (different in the maximum frequency fmax). It is configured to be able to.
　ここで、第２実施形態では、光源駆動部２２１は、光源部２１１の応答特性に基づいて、光源部２１１に供給する電力のピーク電流値Ｉｐが設定ピーク電流値Ｉｏになるように、光源部２１１に供給する電力の電圧値Ｖを設定するように構成されている。 Here, in the second embodiment, the light source driving unit 221 uses the light source unit 221 so that the peak current value Ip of the power supplied to the light source unit 211 becomes the set peak current value Io based on the response characteristics of the light source unit 211. The voltage value V of the electric power supplied to 211 is set.
　また、第２実施形態では、光源駆動部２２１は、検出部２１２の識別情報２１２ａおよび光源部２１１の識別情報２１１ｂと、光源部２１１に供給する電力の電圧値Ｖとの対応関係を表すテーブル２２５ａに基づいて、光源部２１１に供給する電力の電圧値Ｖを設定するように構成されている。 In the second embodiment, the light source driving unit 221 also includes a table 225 a representing the correspondence between the identification information 212 a of the detection unit 212 and the identification information 211 b of the light source unit 211 and the voltage value V of the power supplied to the light source unit 211. The voltage value V of the power supplied to the light source unit 211 is set based on the above.
　具体的には、図９および図１０に示すように、記憶部２２５には、検出部２１２の識別情報２１２ａおよび光源部２１１の識別情報２１１ｂと、光源部２１１に供給する電力の電圧値Ｖとの対応関係を表すテーブル２２５ａが予め記憶されている。なお、記憶部２２５は、テーブル２２５ａを外部機器（図示せず）から取得するように構成されていてもよい。 Specifically, as illustrated in FIGS. 9 and 10, the storage unit 225 includes identification information 212 a of the detection unit 212, identification information 211 b of the light source unit 211, and a voltage value V of power supplied to the light source unit 211. A table 225a representing the correspondence relationship is stored in advance. Note that the storage unit 225 may be configured to acquire the table 225a from an external device (not shown).
　たとえば、図９に示すように、テーブル２２５ａには、検出部２１２の識別情報２１２ａと、光源部２１１からのパルス光のパルス幅ｔｗとの対応関係を示すテーブルを含む。具体的には、識別情報「０１」や「０２」などにそれぞれ対応するように、パルス幅「ｔｗ１１」や「ｔｗ１２」などが設定されている。なお、最大周波数ｆｍａｘが比較的大きい検出部２１２の識別情報２１２ａに対応するパルス幅ｔｗは比較的小さく設定されている。 For example, as shown in FIG. 9, the table 225a includes a table indicating the correspondence between the identification information 212a of the detection unit 212 and the pulse width tw of the pulsed light from the light source unit 211. Specifically, the pulse widths “tw11”, “tw12”, and the like are set so as to correspond to the identification information “01”, “02”, and the like. Note that the pulse width tw corresponding to the identification information 212a of the detection unit 212 having a relatively large maximum frequency fmax is set to be relatively small.
　また、図１０に示すように、テーブル２２５ａには、光源部２１１の識別情報２１１ｂと、光源部２１１に印加される電圧値Ｖとの対応関係を示すテーブルを含む。具体的には、識別情報およびパルス幅ｔｗに対応するように、電圧値Ｖが設定されている。たとえば、識別情報「１０」が取得されるとともに、パルス幅ｔｗ１３が設定されている場合には、制御部２２２（光源駆動部２２１）は、電圧値Ｖ１３を設定する。なお、テーブル２２５ａに設定されている電圧値Ｖは、光源部２１１の発光ダイオード素子１１ａの応答特性を考慮して識別情報２１１ｂごとに設定されている。ここで、本願明細書の応答特性とは、発光ダイオード素子１１ａの立上りおよび立下りの特性のみならず、上記した第１実施形態による光音響画像化装置１００の式（３）の比例定数ｋ、発光ダイオード素子１１ａの個数ｎ、および、設定ピーク電流値Ｉｏの情報を含んでいる。 Further, as shown in FIG. 10, the table 225a includes a table indicating the correspondence between the identification information 211b of the light source unit 211 and the voltage value V applied to the light source unit 211. Specifically, the voltage value V is set so as to correspond to the identification information and the pulse width tw. For example, when the identification information “10” is acquired and the pulse width tw13 is set, the control unit 222 (light source driving unit 221) sets the voltage value V13. The voltage value V set in the table 225a is set for each identification information 211b in consideration of the response characteristics of the light emitting diode element 11a of the light source unit 211. Here, the response characteristics of the present specification include not only the rising and falling characteristics of the light emitting diode element 11a, but also the proportionality constant k in the equation (3) of the photoacoustic imaging apparatus 100 according to the first embodiment described above. Information on the number n of the light emitting diode elements 11a and the set peak current value Io is included.
　そして、制御部２２２（光源駆動部２２１）は、プローブ本体部２０１からケーブル３を介して、検出部２１２の識別情報２１２ａを取得して、取得した識別情報２１２ａに対応するパルス幅ｔｗを設定するように構成されている。そして、制御部２２２（光源駆動部２２１）は、プローブ本体部２０１からケーブル３を介して、光源部２１１の識別情報２１１ｂを取得して、取得した識別情報２１１ｂおよびパルス幅ｔｗに対応する電圧値Ｖを設定するように構成されている。 Then, the control unit 222 (light source driving unit 221) acquires the identification information 212a of the detection unit 212 from the probe main body 201 via the cable 3, and sets the pulse width tw corresponding to the acquired identification information 212a. It is configured as follows. Then, the control unit 222 (light source driving unit 221) acquires the identification information 211b of the light source unit 211 from the probe main body unit 201 via the cable 3, and the voltage value corresponding to the acquired identification information 211b and the pulse width tw. It is configured to set V.
　そして、光源駆動部２２１は、設定された電圧値Ｖを光源部２１１に印加して、光源部２１１に流れる電流のピーク電流値Ｉｐが、設定ピーク電流値Ｉｏになる状態で、被検体Ｐにパルス光を照射するように構成されている。 Then, the light source driving unit 221 applies the set voltage value V to the light source unit 211, and the subject P is applied to the subject P in a state where the peak current value Ip of the current flowing through the light source unit 211 becomes the set peak current value Io. It is configured to emit pulsed light.
　また、第２実施形態による光音響画像化装置２００のその他の構成は、第１実施形態における光音響画像化装置１００と同様である。 Further, other configurations of the photoacoustic imaging apparatus 200 according to the second embodiment are the same as those of the photoacoustic imaging apparatus 100 according to the first embodiment.
　第２実施形態では、以下のような効果を得ることができる。 In the second embodiment, the following effects can be obtained.
　第２実施形態では、上記のように、光源駆動部２２１（制御部２２２）を、光源部２１１の応答特性（識別情報２１１ｂおよびテーブル２２５ａ）に基づいて、光源部２１１に供給する電力のピーク電流値Ｉｐが設定ピーク電流値Ｉｏになるように、光源部２１１に供給する電力の電圧値Ｖを設定するように構成する。ここで、光源部２１１は、電圧が印加された場合に、光源部２１１の応答特性に応じて光源部２１１に流れる電流値の上昇する速度が変化する。この点に着目して、第２実施形態では、光源駆動部２２１を、光源部２１１の応答特性に基づいて、光源部２１１に供給する電力のピーク電流値Ｉｐが設定ピーク電流値Ｉｐになるように、光源部２１１に供給する電力の電圧値Ｖを設定することにより、光源部２１１に供給する電力の電流値を上昇させる速度を適切に設定することができる。 In the second embodiment, as described above, the light source driving unit 221 (control unit 222) causes the peak current of power supplied to the light source unit 211 based on the response characteristics (identification information 211b and the table 225a) of the light source unit 211. The voltage value V of the power supplied to the light source unit 211 is set so that the value Ip becomes the set peak current value Io. Here, when a voltage is applied to the light source unit 211, the speed at which the value of the current flowing through the light source unit 211 increases according to the response characteristics of the light source unit 211 changes. Focusing on this point, in the second embodiment, the light source driving unit 221 is configured so that the peak current value Ip of the power supplied to the light source unit 211 becomes the set peak current value Ip based on the response characteristics of the light source unit 211. In addition, by setting the voltage value V of the power supplied to the light source unit 211, it is possible to appropriately set the speed at which the current value of the power supplied to the light source unit 211 is increased.
　また、第２実施形態では、上記のように、光源駆動部２２１（制御部２２２）を、検出部２１２の識別情報２１２ａおよび光源部２１１の識別情報２１１ｂと、光源部２１１に供給する電力の電圧値Ｖとの対応関係を表すテーブル２２５ａに基づいて、光源部２１１に供給する電力の電圧値Ｖを設定するように構成する。これにより、テーブル２２５ａを用いることにより、比較的複雑な計算式を用いて計算させる必要がない分、容易に、光源部２１１に供給する電力の電圧値Ｖを設定することができる。 In the second embodiment, as described above, the light source driving unit 221 (the control unit 222) causes the identification information 212a of the detection unit 212 and the identification information 211b of the light source unit 211 to be supplied to the light source unit 211. Based on the table 225a representing the correspondence relationship with the value V, the voltage value V of the power supplied to the light source unit 211 is set. Thus, by using the table 225a, the voltage value V of the power supplied to the light source unit 211 can be easily set because it is not necessary to calculate using a relatively complicated calculation formula.
　また、第２実施形態による光音響画像化装置２００のその他の効果は、第１実施形態における光音響画像化装置１００と同様である。 Further, other effects of the photoacoustic imaging apparatus 200 according to the second embodiment are the same as those of the photoacoustic imaging apparatus 100 according to the first embodiment.
　［第３実施形態］
　次に、図１１～図１４を参照して、第３実施形態による光音響画像化装置３００の構成について説明する。第３実施形態では、プローブ本体部３０１に、互いに異なる波長を有するパルス光を照射可能な光源部（第１光源部３１１および第２光源部３１３）が設けられている。なお、上記第１実施形態および上記第２実施形態と同一の構成については、同じ符号を付してその説明を省略する。 [Third Embodiment]
Next, the configuration of the photoacoustic imaging apparatus 300 according to the third embodiment will be described with reference to FIGS. In 3rd Embodiment, the light source part (the 1st light source part 311 and the 2nd light source part 313) which can irradiate the pulse light which has a mutually different wavelength in the probe main-body part 301 is provided. In addition, about the structure same as the said 1st Embodiment and the said 2nd Embodiment, the same code | symbol is attached | subjected and the description is abbreviate | omitted.
　（第３実施形態による光音響画像化装置の構成）
　図１１に示すように、第３実施形態による光音響画像化装置３００には、プローブ本体部３０１と、装置本体部３０２とが設けられている。プローブ本体部３０１は、検出部２１２と、第１光源部３１１と、第２光源部３１３とを含む。また、装置本体部３０２は、光源駆動部３２１と、制御部３２２と、記憶部３２５とを含む。 (Configuration of Photoacoustic Imaging Apparatus According to Third Embodiment)
As shown in FIG. 11, the photoacoustic imaging apparatus 300 according to the third embodiment includes a probe main body 301 and an apparatus main body 302. The probe main body 301 includes a detection unit 212, a first light source unit 311, and a second light source unit 313. Further, the apparatus main body 302 includes a light source driving unit 321, a control unit 322, and a storage unit 325.
　プローブ本体部３０１は、ケーブル３に対して、脱着可能に構成されており、プローブ本体部３０１を他の種類のプローブ本体部３０１に交換することが可能に構成されている。 The probe main body 301 is configured to be detachable from the cable 3, and is configured to be able to replace the probe main body 301 with another type of probe main body 301.
　ここで、第３実施形態では、プローブ本体部３０１には、約８５０ｎｍの波長（中心波長が約８５０ｎｍ）のパルス光を発する第１光源部３１１と、約８５０ｎｍの波長とは異なる約７６０ｎｍの波長（中心波長が約７６０ｎｍ）のパルス光を発する第２光源部３１３とが設けられている。そして、光源駆動部３２１は、第１光源部３１１の応答特性と第２光源部３１３の応答特性とに基づいて、第１光源部３１１に供給する電力のピーク電流値Ｉｐａと第２光源部３１３に供給する電力のピーク電流値Ｉｐｂとが略等しい設定ピーク電流値Ｉｏになるように、第１光源部３１１に供給する電力の第１電圧値Ｖａおよび第２光源部３１３に供給する電力の第２電圧値Ｖｂをそれぞれ設定するように構成されている。なお、約８５０ｎｍの波長は、特許請求の範囲の「第１の波長」の一例である。また、約７６０ｎｍの波長は、特許請求の範囲の「第２の波長」の一例である。 Here, in the third embodiment, the probe main body 301 includes a first light source unit 311 that emits pulsed light having a wavelength of about 850 nm (center wavelength is about 850 nm), and a wavelength of about 760 nm that is different from the wavelength of about 850 nm. And a second light source unit 313 that emits pulsed light (having a center wavelength of about 760 nm). Then, the light source driving unit 321 uses the peak current value Ipa of power supplied to the first light source unit 311 and the second light source unit 313 based on the response characteristics of the first light source unit 311 and the response characteristics of the second light source unit 313. The first voltage value Va of the power supplied to the first light source unit 311 and the first power value of the power supplied to the second light source unit 313 are set so that the peak current value Ipb of the power supplied to Two voltage values Vb are set. The wavelength of about 850 nm is an example of the “first wavelength” in the claims. The wavelength of about 760 nm is an example of the “second wavelength” in the claims.
　また、第１光源部３１１には、予め識別情報３１１ｂが格納されている。また、第２光源部３１３には、予め識別情報３１３ｂが格納されている。そして、第１光源部３１１および第２光源部３１３は、それぞれプローブ本体部３０１に対して、脱着可能に構成されている。 Further, identification information 311b is stored in the first light source unit 311 in advance. The second light source unit 313 stores identification information 313b in advance. The first light source unit 311 and the second light source unit 313 are configured to be detachable from the probe main body 301, respectively.
　検出部２１２は、第２実施形態による検出部２１２と同様に構成されており、予め識別情報２１２ａが格納されている。また、記憶部３２５には、テーブル３２５ａが記憶されている。 The detection unit 212 is configured in the same manner as the detection unit 212 according to the second embodiment, and stores identification information 212a in advance. The storage unit 325 stores a table 325a.
　また、制御部３２１は、検出部２１２の識別情報２１２ａ、第１光源部３１１の識別情報３１１ｂ、および、第２光源部３１３の識別情報３１３ｂと、第１光源部３１１に供給する電力の第１電力値Ｖａおよび第２光源部３１３に供給する電力の第２電力値Ｖｂとの対応関係を表すテーブル３２５ａに基づいて、第１電力値Ｖａおよび第２電力値Ｖｂを設定するように構成されている。 In addition, the control unit 321 includes identification information 212 a of the detection unit 212, identification information 311 b of the first light source unit 311, identification information 313 b of the second light source unit 313, and first power supplied to the first light source unit 311. The first power value Va and the second power value Vb are configured to be set based on a table 325a representing a correspondence relationship between the power value Va and the second power value Vb of the power supplied to the second light source unit 313. Yes.
　具体的には、図１２に示すように、テーブル３２５ａには、検出部２１２の識別情報２１２ａ、第１光源部３１１の識別情報３１１ｂ、および、第２光源部３１３の識別情報３１３ｂとの組み合わせに応じて、それぞれ、第１光源部３１１のパルス光のパルス幅ｔｗａおよび電圧値Ｖａと、第２光源部３１３のパルス光のパルス幅ｔｗｂおよび電圧値Ｖｂとが設定されている。パルス幅ｔｗａおよび電圧値Ｖａと、パルス幅ｔｗｂおよび電圧値Ｖｂとは、第１光源部３１１（第１発光ダイオード素子３１１ａ）の応答特性および第２光源部３１３（第２発光ダイオード素子３１３ａ）の応答特性が考慮して設定されている。 Specifically, as shown in FIG. 12, the table 325a includes combinations of identification information 212a of the detection unit 212, identification information 311b of the first light source unit 311 and identification information 313b of the second light source unit 313. Accordingly, the pulse width twa and voltage value Va of the pulsed light of the first light source unit 311 and the pulse width twb and voltage value Vb of the pulsed light of the second light source unit 313 are respectively set. The pulse width twa and voltage value Va, and the pulse width twb and voltage value Vb are the response characteristics of the first light source unit 311 (first light emitting diode element 311a) and the second light source unit 313 (second light emitting diode element 313a). Response characteristics are set in consideration.
　そして、制御部３２１は、テーブル３２５ａに基づいて、パルス幅ｔｗａおよびｔｗｂと、電圧値ＶａおよびＶｂとを設定して、設定した条件により光源駆動部３２２から第１光源部３１１および第２光源部３１３のそれぞれに、電力を供給するように構成されている。 Then, the control unit 321 sets the pulse widths twa and twb and the voltage values Va and Vb based on the table 325a, and the first light source unit 311 and the second light source unit from the light source driving unit 322 according to the set conditions. Each of 313 is configured to supply power.
　光源駆動部３２２は、図１３に示すように、制御部３２１の指令に基づいて、パルス幅ｔｗａ（トリガ信号τ１１）および電圧値Ｖａに対応した電圧を第１光源部３１１に印加するとともに、パルス幅ｔｗｂ（トリガ信号τ１２）および電圧値Ｖｂに対応した電圧を第２光源部３１３に印加するように構成されている。これにより、第１光源部３１１に流れる電流のピーク電流値Ｉｐａが設定ピーク電流値Ｉｏとなるとともに、第２光源部３１３に流れる電流のピーク電流値Ｉｐｂが設定ピーク電流値Ｉｏとなる。 As shown in FIG. 13, the light source driving unit 322 applies a voltage corresponding to the pulse width twa (trigger signal τ11) and the voltage value Va to the first light source unit 311 based on a command from the control unit 321, A voltage corresponding to the width twb (trigger signal τ12) and the voltage value Vb is applied to the second light source unit 313. Thereby, the peak current value Ipa of the current flowing through the first light source unit 311 becomes the set peak current value Io, and the peak current value Ipb of the current flowing through the second light source unit 313 becomes the set peak current value Io.
　また、図１４に示すように、被検体Ｐの検出対象物により光吸収特性は異なる。たとえば、波長８５０ｎｍの光に対する吸光係数は、脱酸素化ヘモグロビンよりも酸素化ヘモグロビンの方が大きいが、波長７６０ｎｍの光に対する吸光係数は、脱酸素化ヘモグロビンよりも酸素化ヘモグロビンの方が小さい。第３実施形態では、第１光源部３１１は、波長８５０ｎｍのパルス光を被検体Ｐに照射可能であるとともに、第２光源部３１３は、波長７６０ｎｍのパルス光を被検体Ｐに照射可能である。これにより、光音響画像化装置３００は、脱酸素化ヘモグロビンの吸光係数および酸素化ヘモグロビンの吸光係数の差異を利用して、たとえば、血管が動脈または静脈のいずれであるかを判別することが可能に構成されている。 Further, as shown in FIG. 14, the light absorption characteristics differ depending on the detection target of the subject P. For example, the oxygenated hemoglobin has a larger extinction coefficient for light having a wavelength of 850 nm than that for deoxygenated hemoglobin, while the extinction coefficient for light having a wavelength of 760 nm is smaller for oxygenated hemoglobin than that of deoxygenated hemoglobin. In the third embodiment, the first light source unit 311 can irradiate the subject P with pulsed light having a wavelength of 850 nm, and the second light source unit 313 can irradiate the subject P with pulsed light having a wavelength of 760 nm. . Accordingly, the photoacoustic imaging apparatus 300 can determine, for example, whether the blood vessel is an artery or a vein by using the difference between the extinction coefficient of deoxygenated hemoglobin and the extinction coefficient of oxygenated hemoglobin. It is configured.
　また、第３実施形態による光音響画像化装置３００のその他の構成は、第１実施形態における光音響画像化装置１００と同様である。 Further, 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.
　第３実施形態では、以下のような効果を得ることができる。 In the third embodiment, the following effects can be obtained.
　第３実施形態では、上記のように、プローブ本体部３０１には、約８５０ｎｍの波長のパルス光を発する第１光源部３１１と、約８５０ｎｍの波長とは異なる約７６０ｎｍの波長のパルス光を発する第２光源部３１３とが設けられている。そして、光源駆動部３２１は、第１光源部３１１の応答特性と第２光源部３１３の応答特性とに基づいて、第１光源部３１１に供給する電力のピーク電流値Ｉｐａと第２光源部３１３に供給する電力のピーク電流値Ｉｐｂとが略等しい設定ピーク電流値Ｉｏになるように、第１光源部３１１に供給する電力の第１電圧値Ｖａおよび第２光源部３１３に供給する電力の第２電圧値Ｖｂをそれぞれ設定するように構成されている。ここで、一般的に、光源部の波長が異なる場合には、波長に応じて光源部の応答特性が異なる。このため、互いに波長が異なる第１光源部３１１および第２光源部３１３に、同じ電圧値Ｖを有する電力を供給した場合には、第１光源部３１１からのパルス光の光量（ピーク電流値Ｉｐａ）と第２光源部３１３からのパルス光の光量（ピーク電流値Ｉｐｂ）とに違いが生じる。この場合、第１光源部３１１からのパルス光に起因する音響波Ａの強度と、第２光源部３１３からのパルス光に起因する音響波Ａの強度とを比較する際に、光量の違いを考慮した比較的複雑な補正をする必要があるので、光音響画像化装置３００の信号処理を複雑化すると考えられる。この点を考慮して、第３実施形態では、上記のように構成することにより、第１光源部３１１に供給する電力のピーク電流値Ｉｐａと第２光源部３１３に供給する電力のピーク電流値ピーク電流値Ｉｐｂとを略等しくすることができるので、第１光源部３１１からのパルス光に起因する音響波Ａの強度と、第２光源部３１３からのパルス光に起因する音響波Ａの強度とを比較する場合に、比較的複雑な補正をする必要がないので、光音響画像化装置３００の信号処理が複雑化するのを抑制することができる。 In the third embodiment, as described above, the probe light source unit 311 that emits pulsed light with a wavelength of about 850 nm and the pulsed light with a wavelength of about 760 nm that are different from the wavelength of about 850 nm are emitted to the probe main body 301. A second light source unit 313 is provided. Then, the light source driving unit 321 uses the peak current value Ipa of power supplied to the first light source unit 311 and the second light source unit 313 based on the response characteristics of the first light source unit 311 and the response characteristics of the second light source unit 313. The first voltage value Va of the power supplied to the first light source unit 311 and the first power value of the power supplied to the second light source unit 313 are set so that the peak current value Ipb of the power supplied to Two voltage values Vb are set. Here, generally, when the wavelength of the light source unit is different, the response characteristic of the light source unit is different depending on the wavelength. For this reason, when power having the same voltage value V is supplied to the first light source unit 311 and the second light source unit 313 having different wavelengths, the light amount of the pulsed light (peak current value Ipa from the first light source unit 311). ) And the light amount (peak current value Ipb) of the pulsed light from the second light source unit 313 is different. In this case, when comparing the intensity of the acoustic wave A caused by the pulsed light from the first light source unit 311 and the intensity of the acoustic wave A caused by the pulsed light from the second light source unit 313, the difference in the amount of light is calculated. It is considered that the signal processing of the photoacoustic imaging apparatus 300 is complicated because it is necessary to perform a relatively complicated correction in consideration. Considering this point, in the third embodiment, the peak current value Ipa of power supplied to the first light source unit 311 and the peak current value of power supplied to the second light source unit 313 are configured as described above. Since the peak current value Ipb can be made substantially equal, the intensity of the acoustic wave A caused by the pulsed light from the first light source unit 311 and the intensity of the acoustic wave A caused by the pulsed light from the second light source unit 313 , It is not necessary to make a relatively complicated correction, so that the signal processing of the photoacoustic imaging apparatus 300 can be prevented from becoming complicated.
　また、第３実施形態による光音響画像化装置３００のその他の効果は、第１実施形態における光音響画像化装置１００と同様である。 Further, other effects of the photoacoustic imaging apparatus 300 according to the third embodiment are the same as those of the photoacoustic imaging apparatus 100 according to the first embodiment.
　［変形例］
　なお、今回開示された実施形態は、すべての点で例示であって制限的なものではないと考えられるべきである。本発明の範囲は、上記した実施形態の説明ではなく特許請求の範囲によって示され、さらに特許請求の範囲と均等の意味および範囲内でのすべての変更（変形例）が含まれる。 [Modification]
The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is shown not by the above description of the embodiment but by the scope of claims for patent, and further includes all modifications (modifications) within the meaning and scope equivalent to the scope of claims for patent.
　たとえば、上記第１～第３実施形態では、光源部に発光ダイオード素子を用いる例を示したが、本発明はこれに限られない。たとえば、光源部に発光ダイオード素子以外の発光素子を用いてもよい。たとえば、図１５に示す変形例のように、光源部４１１に、半導体レーザ素子４１１ａを用いてもよい。 For example, in the first to third embodiments, the example in which the light emitting diode element is used for the light source unit has been described, but the present invention is not limited to this. For example, you may use light emitting elements other than a light emitting diode element for a light source part. For example, a semiconductor laser element 411a may be used for the light source unit 411 as in the modification shown in FIG.
　また、上記第１および第２実施形態では、制御部（光源駆動部）を、パルス光のパルス幅ｔｗを設定した後に、電圧値を設定するように構成する例を示したが、本発明はこれに限られない。たとえば、制御部（光源駆動部）を、パルス光のパルス幅ｔｗを設定する前に、電圧値を設定するように構成してもよい。すなわち、制御部（光源駆動部）は、光源部に供給する電力のピーク電流値が設定ピーク電流値になるように、検出部の検出周波数が大きいほど、光源部に供給する前記電力の電圧値を大きくするように構成されていればよい。 In the first and second embodiments, the control unit (light source driving unit) is configured to set the voltage value after setting the pulse width tw of the pulsed light. It is not limited to this. For example, the control unit (light source driving unit) may be configured to set the voltage value before setting the pulse width tw of the pulsed light. That is, the control unit (light source driving unit) increases the voltage value of the power supplied to the light source unit as the detection frequency of the detection unit increases so that the peak current value of the power supplied to the light source unit becomes the set peak current value. It suffices if it is configured to increase the size.
　また、上記第２実施形態では、パルス幅を設定するためのテーブル（図９参照）と、電圧値を設定するためのテーブル（図１０参照）とを別々に設ける例を示したが、本発明はこれに限られない。たとえば、第３実施形態のテーブル（図１２参照）のように、第２実施形態のテーブルを１つのテーブルとして構成してもよい。なお、第３実施形態のテーブル（図１２参照）を、第２実施形態のテーブル（図９および図１０参照）のように、パルス幅を設定するためのテーブルと、電圧値を設定するためのテーブルとの別々のテーブルとして構成してもよい。 In the second embodiment, an example in which a table for setting a pulse width (see FIG. 9) and a table for setting a voltage value (see FIG. 10) are provided separately is shown. Is not limited to this. For example, as in the table of the third embodiment (see FIG. 12), the table of the second embodiment may be configured as one table. Note that the table for setting the pulse width and the table for setting the voltage value are the same as the table for the third embodiment (see FIG. 12), like the tables for the second embodiment (see FIGS. 9 and 10). You may comprise as a table separate from a table.
　また、上記第２および第３実施形態では、制御部を、検出部および光源部から識別情報を取得して、取得した識別情報に基づいて、パルス幅および電圧値を設定するように構成する例を示したが、本発明はこれに限られない。たとえば、制御部を、検出部および光源部から識別情報ではなく最大周波数の情報および応答特性の情報を取得して、取得した最大周波数の情報および応答特性の情報に基づいて、パルス幅および電圧値を設定するように構成してもよい。 In the second and third embodiments, the control unit is configured to acquire identification information from the detection unit and the light source unit, and to set the pulse width and voltage value based on the acquired identification information. However, the present invention is not limited to this. For example, the control unit acquires the maximum frequency information and the response characteristic information instead of the identification information from the detection unit and the light source unit, and based on the acquired maximum frequency information and the response characteristic information, the pulse width and the voltage value It may be configured to set.
　また、上記第１～第３実施形態では、光源駆動部を装置本体部に設ける例を示したが、本発明はこれに限られない。たとえば、光源駆動部をプローブ本体部に設けてもよい。 In the first to third embodiments, the example in which the light source driving unit is provided in the apparatus main body has been described. However, the present invention is not limited to this. For example, the light source driving unit may be provided in the probe main body.
　１１、２１１、４１１　光源部
　１１ａ　発光ダイオード素子１１ａ（発光素子）
　１２、２１２　検出部
　２１、２２１、３２１　光源駆動部
　１００、２００、３００　光音響画像化装置
　２１１ｂ、３１１ｂ、３１３ｂ　識別情報（光源部の識別情報）
　２１２ａ　識別情報（検出部の識別情報）
　２２５ａ、３２５ａ　テーブル
　３１１　第１光源部（第１光源、光源部）
　３１３　第２光源部（第２光源、光源部）
　４１１ａ　半導体レーザ素子（発光素子） 11, 211, 411 Light source part 11a Light emitting diode element 11a (light emitting element)
12, 212 Detection unit 21, 221, 321 Light source drive unit 100, 200, 300 Photoacoustic imaging apparatus 211b, 311b, 313b Identification information (identification information of light source unit)
212a Identification information (identification information of the detection unit)
225a, 325a Table 311 1st light source part (1st light source, light source part)
313 2nd light source part (2nd light source, light source part)
411a Semiconductor laser element (light emitting element)

Claims (8)

  1. 　光源部と、
    　前記光源部により被検体に光が照射されることに起因して前記被検体内から発生する音響波を検出する検出部と、
    　前記光源部に電力を供給して前記光源部を駆動させる光源駆動部とを備え、
    　前記光源駆動部は、前記光源部に供給する前記電力のピーク電流値が所定のピーク電流値になるように、前記検出部の検出周波数が大きいほど、前記光源部に供給する前記電力の電圧値を大きくするように構成されている、光音響画像化装置。     A light source unit;
    A detection unit for detecting an acoustic wave generated from within the subject due to light being irradiated to the subject by the light source unit;
    A light source driving unit that supplies power to the light source unit to drive the light source unit,
    The light source driving unit supplies a voltage value of the power supplied to the light source unit as the detection frequency of the detection unit increases so that a peak current value of the power supplied to the light source unit becomes a predetermined peak current value. A photoacoustic imaging device configured to increase the size.
  2. 　前記光源駆動部は、前記検出部の検出周波数に基づいて、前記光源部から照射する光のパルス幅を設定するとともに、前記パルス幅が小さいほど、前記光源部に供給する前記電力の電圧値を大きくするように構成されている、請求項１に記載の光音響画像化装置。 The light source driving unit sets a pulse width of light emitted from the light source unit based on a detection frequency of the detection unit, and the voltage value of the power supplied to the light source unit is decreased as the pulse width is smaller. The photoacoustic imaging apparatus according to claim 1, wherein the apparatus is configured to be large.
  3. 　前記光源駆動部は、互いに直列に接続されたｎ個の発光素子を含み、前記パルス幅をｔｗ、前記所定のピーク電流値をＩｏ、および、所定の比例定数をｋとして、以下の式（１）に表される電圧値Ｖに、前記光源部に供給する前記電力の電圧値を設定するように構成されている、請求項２に記載の光音響画像化装置。
    　Ｖ＝ｎ×１／ｋ×１／ｔｗ×Ｉｏ　・・・　（１）     The light source driving unit includes n light emitting elements connected in series with each other, the pulse width is tw, the predetermined peak current value is Io, and a predetermined proportionality constant is k. The photoacoustic imaging apparatus according to claim 2, wherein the voltage value V of the power supplied to the light source unit is set to the voltage value V represented by
    V = n × 1 / k × 1 / tw × Io (1)
  4. 　前記光源駆動部は、前記検出部が検出することが可能な前記音響波の最大周波数が大きいほど、前記パルス幅を小さく設定するように構成されている、請求項２または３に記載の光音響画像化装置。 4. The photoacoustic according to claim 2, wherein 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. Imaging device.
  5. 　前記光源駆動部は、前記光源部の応答特性に基づいて、前記光源部に供給する前記電力のピーク電流値が前記所定のピーク電流値になるように、前記光源部に供給する前記電力の電圧値を設定するように構成されている、請求項１～４のいずれかに記載の光音響画像化装置。 The light source driving unit supplies the power voltage to the light source unit such that a peak current value of the power supplied to the light source unit becomes the predetermined peak current value based on response characteristics of the light source unit. The photoacoustic imager according to any one of claims 1 to 4, wherein the photoacoustic imager is configured to set a value.
  6. 　前記光源部は、第１の波長の光を発する第１光源と、前記第１の波長とは異なる第２の波長の光を発する第２光源とを含み、
    　前記光源駆動部は、前記第１光源の応答特性と前記第２光源の応答特性とに基づいて、前記第１光源に供給する電力のピーク電流値と前記第２光源に供給する電力のピーク電流値とが略等しいピーク電流値になるように、前記第１光源に供給する電力の第１電圧値および前記第２光源に供給する電力の第２電圧値をそれぞれ設定するように構成されている、請求項５に記載の光音響画像化装置。     The light source unit includes a first light source that emits light of a first wavelength, and a second light source that emits light of a second wavelength different from the first wavelength,
    The light source driving unit is configured to provide a peak current value of power supplied to the first light source and a peak current of power supplied to the second light source based on response characteristics of the first light source and response characteristics of the second light source. The first voltage value of the power supplied to the first light source and the second voltage value of the power supplied to the second light source are respectively set so that the peak current value is substantially equal to the value. The photoacoustic imaging apparatus according to claim 5.
  7. 　前記光源駆動部は、前記検出部の識別情報および前記光源部の識別情報の少なくとも一方と、前記光源部に供給する前記電力の電圧値との対応関係を表すテーブルに基づいて、前記光源部に供給する前記電力の電圧値を設定するように構成されている、請求項１～６のいずれか１項に記載の光音響画像化装置。 The light source driving unit is arranged in the light source unit based on a table representing a correspondence relationship between at least one of the identification information of the detection unit and the identification information of the light source unit and the voltage value of the power supplied to the light source unit. The photoacoustic imaging apparatus according to any one of claims 1 to 6, wherein the photoacoustic imaging apparatus is configured to set a voltage value of the power to be supplied.
  8. 　前記光源部は、発光ダイオード素子および半導体レーザ素子のうちの少なくとも一方を含む、請求項１～７のいずれか１項に記載の光音響画像化装置。 The photoacoustic imaging apparatus according to any one of claims 1 to 7, wherein the light source unit includes at least one of a light emitting diode element and a semiconductor laser element.
PCT/JP2016/068313 2015-06-19 2016-06-20 Photoacoustic imaging device WO2016204303A1 (en)

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JP3607569B2 (en) * 2000-05-08 2005-01-05 一司 山中 Nondestructive inspection method and apparatus for structure
JP2011120795A (en) * 2009-12-11 2011-06-23 Canon Inc Photoacoustic apparatus and method for controlling the same
JP2013128722A (en) * 2011-12-22 2013-07-04 Fujifilm Corp Method and apparatus for photoacoustic imaging
JP2016047232A (en) * 2014-08-27 2016-04-07 プレキシオン株式会社 Photoacoustic imaging apparatus

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP3607569B2 (en) * 2000-05-08 2005-01-05 一司 山中 Nondestructive inspection method and apparatus for structure
JP2011120795A (en) * 2009-12-11 2011-06-23 Canon Inc Photoacoustic apparatus and method for controlling the same
JP2013128722A (en) * 2011-12-22 2013-07-04 Fujifilm Corp Method and apparatus for photoacoustic imaging
JP2016047232A (en) * 2014-08-27 2016-04-07 プレキシオン株式会社 Photoacoustic imaging apparatus

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