JP2019042003A - Photoacoustic apparatus - Google Patents

Abstract

To provide a photoacoustic apparatus capable of widening a frequency bandwidth of a detected acoustic wave by irradiating a subject with pulse lights whose pulse waveforms are different at least partially a plurality of times.SOLUTION: A photoacoustic apparatus includes a control part for controlling a plurality of light irradiation parts so that pulse waveforms of pulse lights irradiated with from the plurality of light irradiation parts are different from each other.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a photoacoustic apparatus.

  In recent years, as an imaging technology using light, a photoacoustic apparatus for imaging the inside of a subject using a photoacoustic effect has been researched and developed. A photoacoustic apparatus is an apparatus which acquires the information regarding a subject based on the ultrasonic wave (photoacoustic wave) generated by the photoacoustic effect from the light absorber which absorbed the energy of the light irradiated to the subject.

  In Patent Document 1, photoacoustic imaging is performed in which the ratio of the rising slope to the falling slope of the light pulse waveform emitted from the light source unit is set so as to be compatible with the frequency band of the detection unit that detects acoustic waves. An apparatus is disclosed.

JP 2017-46823 A

  Patent Document 1 discloses that the absolute value of the ratio of inclination is increased in order to widen the range of detection frequency of the detection unit. However, the parameter for changing the detection frequency is only the slope ratio, and there is a limit to broadening the detection frequency.

  In the photoacoustic apparatus according to the present invention, a plurality of light irradiation units for irradiating pulsed light onto a subject, and a plurality of light irradiation units such that the pulsed light is simultaneously irradiated to the subject from the plurality of light irradiation units A control unit that controls the control unit, a receiving unit that receives an acoustic wave generated by irradiating the subject with pulsed light and converts the acoustic wave into an electrical signal; and acquires information related to the subject based on the electrical signal. A photoacoustic apparatus, comprising: an acquisition unit, wherein the control unit controls the light irradiation unit such that pulse waveforms of pulse light emitted from the plurality of light irradiation units are different from each other. Do.

  According to the photoacoustic apparatus according to the present invention, it is possible to widen the frequency band of the acoustic wave to be detected by irradiating the subject with pulse light having different pulse waveforms. As a result, it is possible to acquire information on a substance having a size corresponding to a low frequency among substances having a size corresponding to a low frequency among light absorbers distributed in a subject. In addition, by increasing the types of pulse waveforms, the frequency band of the detected acoustic wave can be further broadened.

The figure for demonstrating the effect of the photoacoustic apparatus which concerns on embodiment of this invention. Block diagram for explaining a photoacoustic apparatus according to an embodiment of the present invention The figure which shows the structure of the probe concerning the embodiment of the present invention A figure showing an example of composition of a drive part in an embodiment of the present invention The figure which shows an example of the computer structure in embodiment of this invention. A figure for explaining an example of control of a photoacoustic apparatus in an embodiment of the present invention

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, the dimensions, materials, shapes and relative positions of the components described below should be suitably changed according to the configuration of the apparatus to which the invention is applied and various conditions. Therefore, the scope of the present invention is not intended to be limited to the following description.

  The present embodiment relates to a technique for detecting an acoustic wave propagating from a subject, generating characteristic information inside the subject, and acquiring the characteristic information. Therefore, the present embodiment can be understood as an object information acquisition apparatus or a control method thereof, or an object information acquisition method or a signal processing method. The present embodiment can also be grasped as a display method for generating and displaying an image indicating characteristic information inside the subject. The present embodiment can also be regarded as a program that causes an information processing apparatus having hardware resources such as a CPU and a memory to execute these methods, and a non-transitory computer-readable storage medium storing the program. .

  The object information acquisition apparatus according to the present embodiment irradiates light pulses (electromagnetic waves) by a plurality of light irradiation units, and acquires a photoacoustic effect of acquiring characteristic information of the object as image data based on the received photoacoustic signal. Includes the photoacoustic imaging device used. Furthermore, the object information acquiring apparatus according to the present embodiment obtains information based on the frequency characteristic of a desired photoacoustic signal by simultaneously emitting at least two or more types of light pulse waveforms in the light emitting unit. It is a photoacoustic device to be realized. In this case, the characteristic information is information of characteristic values corresponding to each of a plurality of positions in the subject, generated using a signal derived from the received photoacoustic wave.

  The photoacoustic image data according to the present embodiment is a concept including all image data derived from the photoacoustic wave generated by light irradiation. For example, the photoacoustic image data includes at least one object such as a generated sound pressure of a photoacoustic wave (initial sound pressure), an absorbed energy density, an absorption coefficient, and a concentration of a substance constituting the object (such as oxygen saturation). Image data representing the spatial distribution of information. It should be noted that photoacoustic image data showing spectral information such as the concentration of a substance constituting an object is obtained based on signals (photoacoustic signals) derived from photoacoustic waves generated by light irradiation of a plurality of different wavelengths. Be The photoacoustic image data indicating spectral information may be oxygen saturation, a value obtained by weighting the oxygen saturation with an intensity such as an absorption coefficient, total hemoglobin concentration, oxyhemoglobin concentration, or deoxyhemoglobin concentration. Further, photoacoustic image data indicating spectral information may be glucose concentration, collagen concentration, melanin concentration, or a volume fraction of fat or water.

  A two-dimensional or three-dimensional characteristic information distribution is obtained based on the characteristic information of each position in the subject. Distribution data may be generated as image data. The characteristic information may be obtained not as numerical data but as distribution information of each position in the subject. That is, distribution information such as initial sound pressure distribution, energy absorption density distribution, absorption coefficient distribution, and oxygen saturation distribution.

  The present invention is an invention in which light is emitted simultaneously with at least two or more types of light pulse waveforms among a plurality of light irradiation parts, and the object is irradiated with the light to obtain information based on the obtained photoacoustic signal. is there. With such a configuration, the frequency spectrum of the photoacoustic wave generated by the light irradiation, that is, the frequency characteristic of the photoacoustic signal obtained by converting the photoacoustic wave into an electrical signal can be made to have a desired characteristic.

  The acoustic wave referred to in the present embodiment is typically an ultrasonic wave, and includes an acoustic wave and an elastic wave called an acoustic wave. An electrical signal converted from an acoustic wave by a transducer or the like is also referred to as an acoustic signal. However, the description of ultrasonic wave or acoustic wave in the present specification is not intended to limit the wavelength of the elastic wave. The acoustic wave generated by the photoacoustic effect is called photoacoustic wave or photoacoustic wave. An electrical signal derived from a photoacoustic wave is also referred to as a photoacoustic signal. The distribution data is also called photoacoustic image data or reconstructed image data.

  In the following embodiment, as an object information acquisition apparatus, an object is irradiated with a light pulse a plurality of times, and photoacoustic waves from the object are received, and information in the object (for example, blood vessel image (structural image)) Take up the photoacoustic device to get to. However, the effect of the photoacoustic apparatus according to the present embodiment can also be applied to a configuration in which light is emitted simultaneously with at least two or more types of light pulse waveforms, and the object is irradiated with the light pulse once. Although the following embodiments also deal with an optoacoustic apparatus having a hand-held probe, the present invention can also be applied to an optoacoustic apparatus in which a stage is provided with a probe and mechanically scanned. Furthermore, in the following embodiments, a device in which a plurality of semiconductor light emitting elements are mounted inside a hand-held type probe and connected to a photoacoustic apparatus main body by wiring will be described. However, the present embodiment can also be applied to a photoacoustic apparatus that has a power supply such as a battery in a hand-held type probe and wirelessly transmits the photoacoustic signal of the hand-held type probe to the photoacoustic apparatus main body. Thus, when the hand-held probe has the function of the present invention, the photoacoustic apparatus of the present invention can be said to mean the hand-held probe itself.

First Embodiment
First, the basic concept of the present embodiment will be described below.

  FIG. 1 is a graph showing the relationship between an optical pulse waveform and a photoacoustic signal for explaining the basic concept of the present embodiment in an easily understandable manner. FIGS. 1 (a) and 1 (c) are graphs showing light pulse waveforms, in which the vertical axis is light intensity and the horizontal axis is time. FIGS. 1 (b) and 1 (d) are graphs respectively simulating the frequency spectrum of the photoacoustic wave obtained when the object is irradiated with the light pulse waveform shown in FIGS. 1 (a) and 1 (c). The axis is the intensity of the photoacoustic wave, and the horizontal axis is the frequency. As shown in FIG. 1 (a), when the light pulse having a short pulse width (100 nsec) is irradiated, as shown in FIG. 1 (b), the peak value of the photoacoustic wave frequency spectrum is about 7 It will be .5 MHz. On the other hand, as shown in FIG. 1 (c), when the light pulse having a long pulse width (200 nsec) is irradiated, as shown in FIG. 1 (d), the peak value of the photoacoustic wave frequency spectrum is It will be about 3.75 MHz.

  In the first embodiment, information based on the photoacoustic signal is obtained from the photoacoustic signal obtained by simultaneously irradiating the subject with such light pulses having different light pulse waveforms. For example, in the case where there is a light irradiation portion consisting of 12 semiconductor light emitting elements, 6 of them are emitted by the light pulse of the light pulse waveform shown in FIG. 1A, and the remaining 6 are shown in FIG. Light is emitted simultaneously with the light pulse of the light pulse waveform shown in c) to illuminate the object. As a result, to obtain a photoacoustic signal that is the frequency spectrum of the photoacoustic wave obtained by adding the frequency spectrum of the photoacoustic wave shown in FIG. 1 (b) and the frequency spectrum of the photoacoustic wave shown in FIG. 1 (d) Can. Specifically, FIG. 1 (e) shows an optical pulse waveform obtained by simultaneously emitting the light pulse having the light pulse waveform shown in FIGS. 1 (a) and 1 (c). Here, “simultaneous” means that the time of the peak of each light pulse waveform is synchronized and irradiated. In FIG. 1 (e), the vertical axis is light intensity, and the horizontal axis is time. FIG. 1 (f) is a graph simulating the frequency spectrum of the photoacoustic wave obtained when the object is irradiated with the light pulse waveform shown in FIG. 1 (e), and the vertical axis represents the intensity of the photoacoustic wave. , Horizontal axis is frequency. As shown in FIG. 1 (f), when the light pulse waveforms shown in FIGS. 1 (a) and 1 (c) are simultaneously emitted to illuminate the subject, the peak frequency of the photoacoustic wave is about 4. The bandwidth for 25 MHz, -6 dB is about 1.25 MHz to about 10 MHz. This characteristic is shown in FIG. 1 (d), where the peak frequency of the photoacoustic wave is about 3.75 MHz and the bandwidth at which it is -6 dB is about 1.25 MHz to about 6.25 MHz. It becomes an extended characteristic. On the other hand, the bandwidth at which the peak frequency of the photoacoustic wave shown in FIG. 1B is about 7.5 MHz and -6 dB is about 2 MHz to about 12.75 MHz. In such a frequency characteristic, although the characteristic on the high frequency side is sufficiently wide, the level of the low frequency component is low, and the visibility of a blood vessel thicker than 0.75 mm may be deteriorated.

  In addition, for example, an optical pulse waveform with a pulse width of 300 nm (not shown) may be irradiated at the same time. For example, consider the case where there is a light irradiation unit configured to include 12 semiconductor light emitting elements. Of the twelve, four emit light with the pulse waveform shown in FIG. 1 (a), and four emit light simultaneously with the pulse waveform shown in FIG. 1 (c), and the remaining four emit light with the pulse waveform (not shown). It is preferable to simultaneously emit light of a pulse waveform with a pulse width of 300 nm and irradiate the object with the light. When irradiated in this manner, it is possible to further increase the intensity of the photoacoustic wave on the low frequency side.

  As another method, it is possible to easily change the frequency spectrum of the photoacoustic wave by controlling the light intensity. For example, in the case where there is a light irradiation section consisting of 12 semiconductor light emitting elements, 6 of them are irradiated with the light pulse of the light pulse waveform shown in FIG. 1A, and the remaining 6 are shown. The light is emitted simultaneously with a light pulse having a light intensity twice that of the light pulse waveform shown in 1 (c) to illuminate the object. The light pulse waveform is shown in FIG. As a result, the frequency spectrum of the photoacoustic wave shown in FIG. 1 (b) and the frequency spectrum of the photoacoustic wave obtained by adding the frequency spectrum of the photoacoustic wave shown in FIG. 1 (d) with a weight of 1: 2 Can be obtained. FIG. 1 (h) shows the frequency spectrum of the photoacoustic wave. In this case, since the light intensity for irradiating the object with the light pulse of the light pulse waveform shown in FIG. 1C is increased, the high frequency component of the frequency spectrum of the photoacoustic wave shown in FIG. It can be enlarged. As shown in FIG. 1 (h), the peak frequency of the photoacoustic wave is about 5.25 MHz, and the bandwidth at which it is -6 dB is about 1.5 MHz to about 12.75 MHz. Compared with the characteristic shown in FIG. 1 (f), the peak frequency of the photoacoustic wave is about 4.25 MHz, and the bandwidth for -6 dB is about 1.25 MHz to about 10 MHz. It can be widely spread.

  Further, as another method of controlling the light intensity, the number of semiconductor light emitting elements that emit light pulses of each light pulse waveform of the light emitting unit may be increased or decreased. That is, even if the light intensity emitted by each semiconductor light emitting device is the same, the light intensity of the light pulse applied to the object can be controlled by increasing or decreasing the number of semiconductor light emitting devices emitting light. Specifically, in the case where there is a light irradiation section consisting of 12 semiconductor light emitting elements, 4 of them are irradiated with the light pulse of the light pulse waveform shown in FIG. The light is emitted simultaneously with the light pulse shown in FIG. 1 (c). Even with this control, it is possible to obtain the same photoacoustic wave as controlling the semiconductor light emitting element. With such control, since the light intensity of the semiconductor light emitting element itself is not analogically varied, the circuit configuration becomes easy.

  Furthermore, in the embodiment of the present invention, the shape of the light pulse waveform is set so that the frequency of the peak value of the frequency spectrum of the photoacoustic wave obtained by the light pulse having two or more types of light pulse waveforms is different. This is preferable because the frequency spectrum of the photoacoustic wave can be adjusted more easily. In order to make the frequency of the peak value of the frequency spectrum of the photoacoustic wave different, when the light pulse waveform is a triangular wave, the shape of the light pulse waveform may be different in pulse width. Specifically, the pulse width may be selected from 100 nsec to 1000 nsec. For example, a triangular wave having a pulse width of 100 nsec and a pulse width of 200 nsec may be used, or a triangular wave having a pulse width of 200 nsec and 300 nsec may be used. Also, the three triangular waves may be used.

  Alternatively, as shown in FIG. 1I, an optical pulse having an asymmetric light pulse waveform with a rise time of 100 nsec and a fall time of 50 nsec may be used. In this case, the frequency spectrum of the photoacoustic wave as shown in FIG. 1 (j) is obtained. It goes without saying that the present invention can be applied in consideration of such characteristics. The light pulse waveform that can be applied in the present invention may have any shape.

  As described above, it has been described that control of the frequency spectrum of the photoacoustic wave is possible by simultaneously emitting light with at least two or more types of light pulse waveforms among the plurality of semiconductor light emitting elements of the light emitting unit.

  According to the present embodiment, as disclosed in, for example, JP-A-2016-47114, light is generated so that the frequency of the combined waveform of the light pulses approaches the frequency at which the reception sensitivity of the detection unit (reception unit) becomes maximum. The frequency spectrum of the acoustic wave can be adapted. Therefore, the shape and light amount of the light pulse waveform to be emitted simultaneously may be set. In the case of a photoacoustic apparatus which can replace the probe, it is preferable to control the shape of the light pulse waveform and the amount of light simultaneously emitted in accordance with the frequency characteristic of the receiving unit of the probe. In addition, the shape and light amount of the light pulse waveform that is simultaneously emitted may be set in accordance with the frequency spectrum of the photoacoustic wave determined by the thickness of the blood vessel in the region of the object to be noticed. Moreover, in order to be able to control the frequency spectrum of the photoacoustic wave according to the instruction of the user, the shape and the light amount of the light pulse waveform which is simultaneously emitted may be controlled. For example, when the user wants to gaze at a fine blood vessel, the light pulse width to be emitted simultaneously may be set short so as to raise the high band of the frequency spectrum of the photoacoustic wave. Furthermore, when the region of the object to be noticed is in the deep part of the object, the attenuation of the high frequency of the photoacoustic signal becomes large, so the computer automatically raises the high band of the frequency spectrum of the photoacoustic wave. The configuration of the light pulse waveform that emits light simultaneously may be set. Alternatively, a pressure sensor or the like may be provided on the hand-held probe, the pressing force of the probe on the subject may be measured, and the shape of the light pulse waveform that the computer emits simultaneously may be changed according to the magnitude of the pressing force. For example, when the user observes details, he may press the probe unconsciously and strongly. If the pressing force is large, the width of the light pulse to be emitted simultaneously may be set short, and the high band of the frequency spectrum of the photoacoustic wave may be raised.

  As described above, in the photoacoustic apparatus that acquires information based on the photoacoustic signal generated by the pulsed light emitted from the light emitting unit, at least two or more types of light pulses among the pulsed light emitted from the light emitting unit It emits light simultaneously with the waveform. Then, by performing such light emission, it is possible to obtain information based on the frequency characteristic of a desired photoacoustic signal. Although the following description of the present invention shows an embodiment in which light is emitted simultaneously with a plurality of times and three or more types of light pulse waveforms and the obtained photoacoustic signals are added and averaged, the present invention is also applicable to the other light emission control configurations described above. it can.

(Configuration of photoacoustic apparatus)
FIG. 2 shows a block diagram of the photoacoustic apparatus 1 according to the present embodiment. Hereinafter, using the block diagram of FIG. 2, the photoacoustic apparatus 1 according to the present embodiment is configured to substantially irradiate the object 100 with a plurality of light irradiation units 200 and a plurality of light irradiation units 200. The controller 153 includes a controller 153 that controls a plurality of light irradiators to simultaneously emit pulsed light. Here, “substantially simultaneously” does not only mean that the time when the pulsed light is irradiated to the subject is the same, but also includes cases where the irradiation time is shifted to such an extent that the effect of the present invention can be obtained.

  Then, the receiving unit 120 receives an acoustic wave generated by irradiating the subject 100 with pulsed light and converts it into an electrical signal, and an acquiring unit that acquires information on the subject 100 based on the converted electrical signal. It has 151. And control part 153 controls light irradiation part 200 so that pulse waveforms of pulse light irradiated from a plurality of light irradiation parts 200 mutually differ. As described above, since the pulse waveforms of the pulsed light emitted from the plurality of light irradiation units 200 to the subject are different, the frequencies of the acoustic waves generated by the respective pulsed lights are different from each other. Therefore, the frequency band of the acoustic wave to be detected can be broadened by increasing the types of pulse waveforms of the pulsed light irradiated to the object. As a result, it is possible to acquire information on a substance having a size corresponding to a low frequency acoustic wave among light absorbers distributed in a subject, to a substance having a small size corresponding to a high frequency acoustic wave.

  In the present embodiment, the pulse waveforms being different are typically cases where the pulse widths are different, but it is not limited thereto.

  Moreover, in the present embodiment, the control unit 153 may control the light emitting unit 200 so that the peak intensities of the pulsed lights emitted from the plurality of light emitting units 200 are different from each other.

  Further, the light irradiation unit 200 may be configured to include a plurality of semiconductor light emitting elements. In this case, the control unit 153 may control the peak intensity of the pulsed light by controlling the light emission intensity of the light emitting element, or by controlling the number of light emitting elements to be emitted among the plurality of light emitting elements. The peak intensity of pulsed light may be controlled.

  The photoacoustic apparatus according to the present embodiment includes a probe 180, a signal collection unit 140, a computer 150, a display unit 160, and an input unit 170. The probe 180 includes a light irradiator 200, a driver 210, and a receiver 120. The computer 150 includes 151, a storage unit 152, and a control unit 153. In addition, the part connected by the cable except the probe 180 can also be described as a photoacoustic apparatus main body.

  In the present embodiment, the light irradiation unit 200 may be configured to include a light source unit. Further, the light source unit may be configured to include a plurality of semiconductor light emitting elements. In order to improve the S / N ratio of the photoacoustic signal, light is emitted a plurality of times, and the photoacoustic signal is acquired and averaged. In order to realize the effects of the present invention, the semiconductor light emitting device may emit light once. The drive unit 210 drives the light emission of the plurality of semiconductor light emitting elements of the light irradiation unit 200 so as to have the above-described at least two or more types of light pulse waveforms. The driver 210 controls the light pulse waveform of the light source 200 for each semiconductor light emitting element to emit light. The light pulse waveform may be determined as described above.

  The driving unit 210 divides a plurality of semiconductor light emitting elements of the light source 200 into groups of at least two or more types of light pulse waveforms, and simultaneously emits light. Then, the light source 200 simultaneously irradiates the subject 100 with two or more types of light pulse waveforms. The receiving unit 120 receives the photoacoustic wave generated from the subject 100 by the light emission of the plurality of semiconductor light emitting elements, and outputs an electrical signal (photoacoustic signal) that is an analog signal. The signal collecting unit 140 converts an analog signal output from the receiving unit 120 at each light emission into a digital signal, and outputs the digital signal to the computer 150.

  The computer 150 uses the acquisition unit 151, the storage unit 152, and the control unit 153 to generate an electrical signal derived from the photoacoustic wave (a synthesized photoacoustic signal from the digital signal output from the signal collection unit 140 in each light emission). As a storage unit 152). In order to improve the S / N ratio, it is preferable to emit a plurality of light pulses and perform averaging.

  The computer 150 performs processing such as image reconstruction on the digital signals stored in the storage unit 152 to generate photoacoustic image data. The photoacoustic image data is then displayed on the display unit 160.

  The computer 150 also controls the overall operation of these devices and performs setting of light pulse waveforms and emission control.

  Although not shown, the computer 150 may perform image processing for display and processing for synthesizing a graphic for a GUI on the obtained photoacoustic image data as necessary.

  The user (a doctor, an engineer, etc.) can carry out a diagnosis by confirming the photoacoustic image displayed on the display unit 160. The display image may be stored in a memory in the computer 150, a data management system connected to the photoacoustic apparatus via a network, or the like based on a storage instruction from a user or the computer 150. The input unit 170 receives an instruction from the user.

(Detailed configuration of each block)
Subsequently, the preferred configuration of each block will be described in detail.

(Probe 180)
FIG. 3 is a diagram showing the structure of the probe 180 of the first embodiment.

  In FIG. 3, the probe 180 includes a light irradiator 200, a driver 210, a receiver 120, and a housing 181. The housing 181 is a housing that encloses the light emitting unit 200, the driving unit 210, and the receiving unit 120. The user can use the probe 180 as a handheld probe by gripping the housing 181.

  The light irradiation unit 200 irradiates the light pulse to the subject. As described above, the light emitting unit 200 causes the drive unit 210 to emit light pulses with a desired light pulse waveform for each light pulse emission.

  The XYZ axes in the figure indicate coordinate axes when the probe is left stationary, and do not limit the direction when using the probe.

  The probe 180 shown in FIG. 3 is connected to the signal collecting unit 140 via the cable 182. The cable 182 includes a wire for supplying power to the light emitting unit 200, a light emission control signal wire, and a wire for outputting an analog signal output from the receiving unit 120 to the signal collecting unit 140. The cable 182 may be provided with a connector so that the probe 180 and the other configuration of the photoacoustic apparatus can be separated.

(Light irradiation unit 200)
The light irradiation unit in the present embodiment irradiates the subject with pulsed light generated from the light source.

  For example, the light irradiation unit 200 is configured of 16 semiconductor light emitting elements (for example, laser diodes). The type of the semiconductor light emitting element is not limited to the laser diode (LD), and may be a light emitting diode (LED). The type and number of semiconductor light emitting devices are determined from the required light intensity. Eight laser diodes (200a to 200h) and eight laser diodes (200i to 200p) are disposed to face each other with the receiving unit 120 interposed therebetween. Then, the sample is irradiated with light. Each laser diode is mounted in the direction of maximum sensitivity of the receiver 200. That is, as shown in FIG. 3, the laser diodes (200a to 200h) and the laser diodes (200i to 200p) are mounted at an angle so as to be directed to the receiving unit 120. Further, FIG. 3 shows a mounting arrangement in which the receiving unit 200 is sandwiched, but may be an arrangement in which light sources are collected on one side. Furthermore, the number of laser diodes used may be more than sixteen. Although FIG. 3 shows a mounting form in which discrete components are arranged, a configuration in which a plurality of dies from which a semiconductor wafer is cut out may be mounted on a metal base or a printed board may be used. The arrangement of the laser diodes is not limited to this arrangement. As long as the object can be irradiated with the light pulse satisfactorily, it may be mounted in any arrangement depending on conditions such as the shape of the probe.

  The pulse width of the light emitted from the light irradiation unit 200 is, for example, 10 ns or more and 1 μs or less. More preferably, 100 ns or more and 800 ns or less are preferable. Moreover, as a wavelength of the light of the light irradiation part 200, although 400 nm or more and 1600 nm or less are suitable, it is good to determine a wavelength according to the light absorption characteristic of the light absorber which you want to image. In the case of imaging blood vessels with high resolution, wavelengths (400 nm or more and 800 nm or less) in which absorption in blood vessels is large may be used. In the case of imaging a deep part of a living body, light of a wavelength (700 nm or more and 1100 nm or less) with less absorption in background tissue (water, fat and the like) of the living body may be used. In the present invention, it is possible to acquire structural information of a blood vessel as a desired wavelength, 975 nm which is a wavelength that reaches the deep part of the subject, and simultaneously irradiate light sources of a plurality of other wavelengths that satisfy the above conditions. A photoacoustic wave equivalent to the photoacoustic wave by irradiation can be obtained.

(Drive unit 210)
The structure of the drive part 210 of 1st Embodiment is each shown to Fig.4 (a) (b). Either of the configurations can preferably correspond to the present invention. First, the configuration of the drive unit 210 shown in FIG. 4A will be described. In FIG. 4A, the light irradiation unit 200 includes two sets of a plurality of semiconductor light emitting elements (laser diodes) 200A and 200B connected in series. For example, a plurality of semiconductor light emitting devices 200A connected in series correspond to eight laser diodes (200a to 200h), and a plurality of semiconductor light emitting devices 200B connected in series correspond to eight laser diodes (200i to 200p). In another configuration, the plurality of semiconductor light emitting devices 200B connected in series with the plurality of semiconductor light emitting devices 200A connected in series may be alternately mounted with the reception unit 120 interposed therebetween. In the former case, wiring between a plurality of semiconductor light emitting elements connected in series can be performed at the shortest distance, and there is an advantage that the inductance component can be minimized. On the other hand, in the latter case, the light pulse of each light pulse waveform is an object There is an advantage that can be irradiated almost uniformly.

  The transistors 210 a and 210 b are, for example, MOSFETs, and control the currents flowing through the plurality of semiconductor light emitting elements 200 A and 200 B connected in series with the light irradiation unit 200 with different pulse widths. A power supply 210 c supplies power to the semiconductor light emitting element of the light emitting unit 200. Here, in the case of the hand-held type probe, the power source 210 c may be mounted on the photoacoustic apparatus main body outside the probe to supply power. In this case, in order to reduce the impedance (inductance component) of the power supply, a bypass capacitor (not shown) or the like may be mounted in the probe. By controlling the gate voltage of the transistors 210a and 200b, it is possible to obtain two types of current waveforms flowing in the plurality of semiconductor light emitting elements 200A and 200B connected in series of the light irradiation unit 200 corresponding to the desired light pulse waveform. By realizing such a drive unit 210, it is possible to realize simultaneously emitting light with at least two or more types of light pulse waveforms described above.

  Another configuration of the drive unit 210 is shown in FIG. Also in FIG. 4B, the light irradiation unit 200 is composed of two sets of a plurality of semiconductor light emitting elements (laser diodes) (200A, 200B) connected in series.

  The transistors 210a and 210b are, for example, MOSFETs, and perform ON / OFF control of currents flowing in the plurality of semiconductor light emitting elements 200A and 200B connected in series with the light irradiation unit 200 with different pulse widths.

  Reference numerals 210 d and 210 e denote inductors, which are realized by, for example, a coil, wiring of a printed board, or the like. When controlling a plurality of semiconductor light emitting elements 200A and 200B connected in series with different pulse widths, the inductances of the inductors 210d and 210e are designed to be different. If the pulse width is to be shortened, the inductance should be reduced. Reference numerals 210f and 210g denote diodes, and when the transistors 210a and 210b are turned off, the current flowing through the inductors 210d and 210e is returned to the inductors 210d and 210e. 210h is a variable voltage power supply. Here, when waiting for freedom by setting each pulse width, two variable voltage power supplies 210h are provided so that voltages can be set independently. In the case of a hand-held probe, the variable voltage power supply 210 h may be mounted on the photoacoustic apparatus main body outside the probe. In this case, in order to reduce the impedance (inductance component) of the power supply, a bypass capacitor (not shown) or the like is mounted in the probe. In the configuration of FIG. 4B, the case where the transistor 210a is turned on is considered. At this time, the voltage of the sum of the forward voltages of the plurality of semiconductor light emitting elements 200A connected in series of the light irradiation unit 200, the voltage of the sum of the drain-source voltage when the transistor 210a is ON, and the output of the variable voltage power supply 210h A voltage difference with the voltage is applied to the inductor 210d. The slope of the current flowing through the inductor 210d can be determined by the voltage applied to the inductor 210d and the inductance of the inductor 210d. That is, if the inductance is fixed, the slope of the current flowing through the inductor 210d can be increased by increasing the voltage of the variable voltage power supply 210h. That is, the inclination of the current flowing through the plurality of semiconductor light emitting elements 200A connected in series of the light emitting unit 200 can be controlled. Then, the rising waveform of the light pulse waveform can be determined. When the transistor 210a is turned off, the voltage applied to the inductor 210d is the sum of the forward voltages of the plurality of semiconductor light emitting devices 200A connected in series and the total voltage of the forward voltages of the diode 210f. The slope of the current flowing through the inductor 210d is determined by this voltage and the inductance of the inductor 210d. That is, the falling waveform of the light pulse waveform is determined. For example, it is assumed that the drain-source voltage when the transistor 210a is ON or the forward voltage of the diode 210f is sufficiently smaller than the sum of the forward voltages of the plurality of semiconductor light emitting devices 200A connected in series. In that case, the output voltage of the variable voltage power supply 210h may be set to a voltage that is twice the voltage of the sum of the forward voltages of the plurality of semiconductor light emitting elements 200A connected in series. By such setting, the slopes of the rising waveform and the falling waveform of the current flowing through the plurality of semiconductor light emitting elements 200A connected in series can be made the same. Therefore, the slope of the rising waveform and the falling waveform of the light pulse waveform can be made substantially the same. Further, by connecting the anode of the diode 210f to the other electrode of the inductor 210d, the fall time of the current flowing through the plurality of semiconductor light emitting elements 200A connected in series can be shortened when the transistor 210a is turned off. Thus, it is possible to obtain a desired light pulse waveform by using the inductor 210d and the variable power supply 210h.

  Similarly, the slopes of the rising and falling waveforms of the current flowing through the plurality of semiconductor light emitting elements 200B connected in series in the light irradiation unit 200, that is, the light pulse waveforms are also desired waveforms using the inductor 210e and the variable power supply 210h. Can be controlled.

(Receiver 120)
The receiving unit 120 includes a transducer that receives a photoacoustic wave generated as a result of the light emission of the light emitting unit 200 and outputs an electrical signal, and a support that supports the transducer. For example, a piezoelectric material, a capacitive transducer, a transducer using a Fabry-Perot interferometer, or the like can be used as a member constituting the transducer. Examples of the piezoelectric material include piezoelectric ceramic materials such as PZT (lead zirconate titanate) and polymeric piezoelectric film materials such as PVDF (polyvinylidene fluoride). In addition, a capacitive type transducer may be called CMUT (Capacitive Micro-machined Ultrasonic Transducers).

  The electrical signal obtained by the transducer for each light emission of the light emitting unit 200 is a time-resolved signal. Therefore, the amplitude of the electrical signal represents a value based on the sound pressure received by the transducer at each time (for example, a value proportional to the sound pressure). In addition, as a transducer, what can detect the frequency component (typically 100 KHz to 10 MHz) which comprises a photoacoustic wave is preferable. It is also preferable to arrange a plurality of transducers side by side on the support to form a flat surface or a curved surface called 1D array, 1.5D array, 1.75D array, or 2D array. Note that FIG. 3 schematically shows a 1D array transducer as an example.

  The receiver 120 may include an amplifier that amplifies the time-series analog signal output from the transducer. Also, the receiving unit 120 may include an A / D converter that converts a time-series analog signal output from the transducer into a time-series digital signal. That is, the receiving unit 120 may include the signal collecting unit 140.

  In addition, in order to detect an acoustic wave from various angles and to improve an image precision, the transducer arrangement | positioning which encloses the test object 100 from the whole circumference is preferable. Also, if the subject 100 is large enough to not surround the entire circumference, the transducer may be placed on a hemispherical support. The probe 180 including the receiving unit 120 having such a shape is not a handheld type, but is suitable for a mechanical scanning type photoacoustic apparatus that moves the probe relative to the subject 100. A scanning unit such as an XY stage may be used to move the probe. The arrangement and number of transducers, and the shape of the support are not limited to the above, and may be optimized according to the subject 100.

  In the space between the receiving unit 120 and the subject 100, a medium for propagating the photoacoustic wave may be disposed. This matches the acoustic impedance at the interface between the subject 100 and the transducer. Examples of the medium include water, oil, ultrasonic gel and the like.

  The photoacoustic apparatus 1 may include a holding member that holds the subject 100 and stabilizes the shape. It is preferable that the holding member be high in both light transmission and acoustic wave transmission. For example, polymethylpentene, polyethylene terephthalate, acrylic and the like can be used.

  When the apparatus according to the present embodiment generates an ultrasonic image by transmitting and receiving acoustic waves in addition to the photoacoustic image, the transducer may function as a transmitting unit that transmits the acoustic waves. The transducer as the receiving means and the transducer as the transmitting means may be a single (common) transducer or may be separate configurations.

(Signal collecting unit 140)
The signal collecting unit 140 includes an amplifier for amplifying an electric signal which is an analog signal output from the receiving unit 120 generated for each light emission of the light emitting unit 200, and an A / D for converting the analog signal output from the amplifier to a digital signal. And a converter. The signal collection unit 140 may be configured by an FPGA (Field Programmable Gate Array) chip or the like.

  The operation of the signal processing unit 140 will be described in more detail. Analog signals output from a plurality of transducers arranged in an array of the receiving unit 120 are amplified by a plurality of amplifiers corresponding to each, and converted into digital signals by a plurality of A / D converters corresponding to each. The A / D conversion rate is performed at least twice or more of the band of the input signal. As described above, if the frequency component of the photoacoustic wave is 100 KHz to 10 MHz, conversion is performed at a frequency of 20 MHz or more, preferably 40 MHz. Note that the signal collection unit 140 synchronizes the timing of the light irradiation and the timing of the signal collection process by using the light emission control signal. That is, A / D conversion is started at the above-described A / D conversion rate based on the light emission time for each light emission of the light emitting unit 200, and an analog signal is converted into a digital signal. As a result, it is possible to acquire, for each of the plurality of transducers, digital data strings for each time interval (A / D conversion interval) of 1 / A / D conversion rate from the light emission time for each light emission of the light emitting unit 200. At this time, the light emission time may be determined based on the time when the light pulse waveform peaks.

  The signal acquisition unit 140 is also called a data acquisition system (DAS). In the present specification, an electrical signal is a concept that includes both an analog signal and a digital signal.

  As described above, the signal collection unit 140 may be disposed inside the housing 181 of the probe 180. With such a configuration, the information between the probe 180 and the computer 150 is transmitted as a digital signal, so the noise resistance is improved. Further, the number of wires can be reduced by using a high-speed digital signal as compared with the case of transmitting an analog signal, and the operability of the probe 180 is improved.

  Also, the signal acquisition unit 140 may perform an addition averaging described later. In this case, it is preferable to perform averaging using hardware such as an FPGA.

(Computer 150)
The computer 150 includes an acquisition unit 151, a storage unit 152, and a control unit 153. The unit responsible for the arithmetic function as the acquisition unit 151 can be configured by a processor such as a CPU or a graphics processing unit (GPU), or an arithmetic circuit such as a field programmable gate array (FPGA) chip. These units may be composed of a single processor or arithmetic circuit, or may be composed of a plurality of processors or arithmetic circuits.

  For example, the computer 150 sets a waveform to be driven by the drive unit 210 so as to drive the plurality of semiconductor light emitting elements connected in series of the light emitting unit 200 with two or more types of light pulse waveforms. The computer 150 is also light intensity setting means for setting the light intensity of each of the at least two or more types of light pulse waveforms described above. It is also a light emission number setting unit that controls the number of light emission of a semiconductor light emitting element that emits light with at least two or more types of light pulse waveforms.

  In the following embodiments, an embodiment will be described in which the semiconductor light emitting elements emit the same number of light and emit light with a constant light intensity. Of course, it is possible to cope with the other control of light emission described above.

  The computer 150 adds and averages each of the data of the same time from the light emission time of the above-mentioned digital data string output from the signal collection unit 140 for each light emission of the light emission unit 200. Then, the computer 150 stores the arithmetically averaged digital data string in the storage unit 152 as an arithmetically averaged electrical signal (synthesized photoacoustic signal) derived from the photoacoustic wave. Then, based on the combined photoacoustic signal stored in the storage unit 152, the acquisition unit 151 executes generation of photoacoustic image data (structural image or functional image) by image reconstruction and various other arithmetic processing. Do. The acquisition unit 151 may receive input of various parameters such as the sound velocity of the object and the configuration of the holding unit from the input unit 170, and may use them for calculation.

  As a reconstruction algorithm when the acquisition unit 151 converts an electrical signal into three-dimensional volume data, any method such as back projection in the time domain, back projection in the Fourier domain, model-based method (repeated operation method), etc. Method can be adopted. As back projection methods in the time domain, Universal back-projection (UBP), Filtered back-projection (FBP), Delay-and-Sum, etc. may be mentioned.

  Note that the acquisition unit adds a plurality of electrical signals obtained based on the acoustic wave received by the plurality of light emitting units emitting light a plurality of times and divides the sum by the number of times of light emission of the light emitting unit (additional averaging processing ) May be performed.

  The storage unit 152 is configured of a volatile memory such as a random access memory (RAM), a read only memory (ROM), and a non-temporary storage medium such as a magnetic disk or a flash memory. The storage medium in which the program is stored is a non-temporary storage medium. In addition, the storage unit 152 is configured of a plurality of storage media.

  The storage unit 152 can store various data such as a combined photoacoustic signal, photoacoustic image data generated by the acquisition unit 151, and reconstructed image data based on the photoacoustic image data.

  The control unit 153 is configured of an arithmetic element such as a CPU. The control unit 153 controls the operation of each component of the photoacoustic apparatus. The control unit 153 sends, to the drive unit 210, light emission control signals of a plurality of light pulses and setting signals of light pulse waveforms. Then, the semiconductor light emitting element emits light with the designated light pulse waveform to irradiate the object. The controller 153 is also an optical pulse waveform setting unit that sets an optical pulse waveform.

  Further, as described above, the control unit 153 controls the light pulse waveform, the light intensity of the light pulse, the number of times of light emission, the amplification degree of the photoacoustic signal, etc. by the user's instruction or automatically. Further, the control unit 153 reads out the program code stored in the storage unit 152, and controls the operation of each component of the photoacoustic apparatus.

  Further, the control unit 153 performs adjustment of the image on the display unit 160 and the like. As a result, an oxygen saturation distribution image is sequentially displayed along with the movement of the probe and the photoacoustic measurement.

  Computer 150 may be a workstation specifically designed for the present invention. The computer 150 may also operate a general-purpose PC or a work station according to an instruction of a program stored in the storage unit 152. Also, each configuration of the computer 150 may be configured by different hardware. Also, at least a part of the configuration of the computer 150 may be configured by a single piece of hardware.

  FIG. 5 shows a specific configuration example of the computer 150 according to the present embodiment. The computer 150 according to the present embodiment includes a CPU 154, a GPU 155, a RAM 156, a ROM 157, and an external storage device 158. Further, a liquid crystal display 161 as the display unit 160, a mouse 171 as the input unit 170, and a keyboard 172 are connected to the computer 150.

  Also, the computer 150 and the receiving unit 120 may be provided in a configuration housed in a common housing. Alternatively, part of the signal processing may be performed by a computer housed in a housing, and the remaining signal processing may be performed by a computer provided outside the housing. In this case, the computers provided inside and outside the housing can be collectively referred to as the computer according to the present embodiment. That is, the hardware constituting the computer may not be housed in one housing. As the computer 150, an information processing apparatus installed at a remote place provided by a cloud computing service or the like may be used.

  The computer 151 corresponds to the processing unit of the present invention. In particular, the acquisition unit 151 mainly implements the function of the processing unit.

(Display unit 160)
The display unit 160 is a display such as a liquid crystal display or an organic EL (Electro Luminescence). This is an apparatus for displaying an image based on object information (for example, structure information or function information) obtained by the computer 150 or a numerical value of a specific position. The display unit 160 may display an image or a GUI for operating the device. Image processing (adjustment of luminance value, etc.) may be performed on the display unit 160 or the computer 150.

(Input unit 170)
As the input unit 170, an operation console that can be operated by the user and configured with a mouse, a keyboard, and the like can be adopted. In addition, the display unit 160 may be configured by a touch panel, and the display unit 160 may be used as the input unit 170. The input unit 170 receives an instruction from a user, an input such as a numerical value, and the like, and transmits the input to the computer 150.

  Each configuration of the photoacoustic apparatus may be configured as a separate apparatus, or may be configured as one integrated apparatus. Further, at least a part of the configuration of the photoacoustic apparatus may be configured as one integrated device.

  The computer 150 also performs drive control of the configuration included in the photoacoustic apparatus by the control unit 153. In addition to the image generated by the computer 150, the display unit 160 may display a GUI or the like. The input unit 170 is configured to allow the user to input information. The user can use the input unit 170 to perform operations such as measurement start and end, designation of an irradiation mode to be described later, and an instruction to save a created image.

(Subject 100)
The subject 100 does not constitute a photoacoustic apparatus, but will be described below. The photoacoustic apparatus according to the present embodiment can be used for the purpose of diagnosis of malignant tumors and vascular diseases of humans and animals and follow-up of chemical treatment. Therefore, the object 100 is assumed to be an object of diagnosis of a living body, specifically a breast or each organ of a human body or an animal, a blood vessel network, a head, a neck, an abdomen, an extremity including a finger and a toe. Ru. For example, if the human body is to be measured, oxyhemoglobin or deoxyhemoglobin, or a blood vessel containing many of them or a neovascular formed in the vicinity of a tumor may be used as the light absorber. In addition, plaque or the like of the carotid artery wall may be a target of the light absorber. In the case of the human body as a subject, melanin, which is a pigment contained in the skin, can be a light absorber that generates the above-mentioned interference. In addition, a pigment such as methylene blue (MB) or indosine green (ICG), gold fine particles, or a substance introduced from the outside obtained by accumulating or chemically modifying them may be used as the light absorber. In addition, a puncture needle or a light absorber attached to the puncture needle may be an observation target. The subject may be an inanimate object such as a phantom or a test object.

(Operation of the embodiment)
Next, the subject information acquiring apparatus according to the present invention irradiates the subject with light pulses of at least two or more types of light pulse waveforms multiple times, receives an acoustic wave generated in the subject for each irradiation, and receives Characteristic information of the object is acquired based on the photoacoustic signal. In the first embodiment, a detailed description will be given below of a configuration in which eight semiconductor light emitting elements simultaneously emit light of two light pulse waveforms.

  FIG. 6 is a timing chart for easily explaining the operation in the first embodiment. In FIG. 6, the horizontal axis is a time axis. The control is performed by the computer 150 or an FPGA or dedicated hardware. Acquisition of the photoacoustic signal of the photoacoustic apparatus of this invention and the method of producing | generating the photoacoustic image based on the acquired photoacoustic signal are demonstrated in detail using FIG.

  FIG. 6 is a timing chart for simultaneously emitting light pulses of two types of light pulse waveforms and obtaining structural information from the obtained photoacoustic signal. In addition, when acquiring the structural information of a blood vessel, it is good for the wavelength of the light irradiation part 200 to select about 795 nm from which the absorption coefficient of oxyhemoglobin and deoxyhemoglobin becomes equal.

  Since the light intensity of the semiconductor light emitting device is small, the photoacoustic apparatus is configured to irradiate a plurality of semiconductor light emitting devices of the light emitting unit 200 with an irradiation cycle of tw1 as shown in T1 of FIG. The light emission is repeated repeatedly to acquire the photoacoustic signal. The length of the irradiation cycle: tw1 is set in consideration of the Maximum Permissible Exposure (MPE) to the skin. For example, 0.1 mSec may be selected as the irradiation cycle tw1.

  As shown in FIG. 3, the light irradiation part 200 is comprised by 16 laser diodes as a semiconductor light-emitting element. The eight laser diodes (200a to 200h) have the light pulse waveform shown in FIG. 1 (a), and the laser diodes (200i to 200p) have the light pulse waveform shown in FIG. 1 (c). Period: The light is emitted simultaneously and repeatedly at tw1 intervals to acquire a photoacoustic signal. Here, the arrangement and the total number of laser diodes and the number of laser diodes emitting light with two types of light pulse waveforms are only an example, and other configurations may be used. It may be determined from the required light intensity, desired frequency characteristics, and the like.

  At T1 in FIG. 6, the light pulse waveform in FIG. 1 (a) and the light pulse in FIG. 1 (c) are simultaneously emitted, and the photoacoustic signal is acquired 168 times at the irradiation cycle tw1 ((1) ~ (4) ...) Add averaging. Then, the averaged photoacoustic signal A1 is obtained for each period of the imaging frame rate: tw2. That is, as described above, by simultaneously emitting the light pulse waveform of FIG. 1 (a) and the light pulse waveform of FIG. 1 (c), an optical pulse equivalent to the light pulse waveform shown in FIG. 1 (e) is obtained. Irradiate the subject. And the photoacoustic wave of the frequency spectrum shown to FIG. 1 (f) can be obtained for every period of imaging frame rate: tw2. Then, the obtained 166 photoacoustic signals are subjected to addition averaging to calculate an addition averaged photoacoustic signal A1.

  Next, as shown at T3 in FIG. 6, the above-described processing for reconstruction is performed based on the averaged photoacoustic signal A1 to obtain reconstructed image data R1. Then, the reconstructed image data R1 is sequentially output and displayed on the display unit 160 as structure information S1 with a period tw2 of an imaging frame rate of 16.6 msec (T4 in FIG. 6). The frequency of the imaging frame rate is approximately 60 Hz.

  When the photoacoustic signal is acquired 166 times and averaging is performed, the frequency of the imaging frame rate is about 60 Hz, which matches the display frame rate of the display unit 160, but when the number of averaging times is different, the imaging frame rate and display Frame rates may not match. In this case, the imaging frame rate may be converted to a display frame rate using a frame rate converter (not shown) and displayed on the display unit 160.

  As described above, by simultaneously emitting light with at least two or more types of light pulse waveforms among the plurality of semiconductor light emitting elements of the light irradiation unit 200, information based on the frequency characteristics of a predetermined (desired) photoacoustic signal is obtained It becomes possible.

  As a result, it is possible to obtain information that is more optimal for the photoacoustic signal frequency characteristics.

  In the first embodiment, the configuration is such that two or more different light pulse waveforms are controlled to emit light simultaneously. When averaging the photoacoustic signals obtained by emitting a plurality of times, part of the emission among the plurality of times of emission is controlled such that two or more different light pulse waveforms of the present invention are emitted simultaneously; Light emission may be performed by light pulses of one type of light pulse waveform to illuminate the subject. In this case, the frequency spectrum of the photoacoustic wave by one type of light pulse waveform and the frequency spectrum of the photoacoustic wave obtained by simultaneously emitting two or more different light pulse waveforms are weighted by the number of times of light emission. The frequency characteristic of the averaged photoacoustic signal is obtained.

(Other embodiments)
In the first embodiment, an embodiment has been described in which a photoacoustic signal is obtained by simultaneously emitting light with at least two or more types of light pulse waveforms among a plurality of semiconductor light emitting elements of a light irradiation unit and irradiating an object. As described above, among the plurality of semiconductor light emitting devices, the number of semiconductor light emitting devices corresponding to each light pulse waveform may be changed. In addition, the light intensity of the semiconductor light emitting element that emits the light pulse of each light pulse waveform may be changed to simultaneously emit light to obtain the photoacoustic signal.

  Moreover, the wavelength of the light which light irradiation part 200 light-emits may use several wavelength. When a plurality of wavelengths are used, oxygen saturation as functional information can be calculated. In the present invention, for example, two wavelengths are alternately switched for each imaging frame rate, photoacoustic signals are acquired, reconstructed image data is calculated, and oxygen saturation is calculated from reconstructed image data calculated at two imaging frame rates. It can be calculated. The calculation of the oxygen saturation is described in detail in JP-A-2015-142740. Furthermore, when obtaining structural information, the object is simultaneously irradiated with the two or more types of light pulse waveforms of this embodiment to obtain information of wide frequency characteristics. Then, the light pulse waveform of the other wavelength for obtaining the function information may have a shape of one light pulse waveform in which the pulse width is extended. By doing this, the structural information can be clearly detected regardless of the thickness of the blood vessel, and the functional information can obtain information without high frequency components. The function information can be made detailed information by masking it with the structure information.

  In addition, the plurality of embodiments described above may be realized by one photoacoustic apparatus, and may be switched and used. Furthermore, the photoacoustic apparatus of the present invention may be additionally realized with the function of transmitting ultrasonic waves from a transducer and performing measurement using a reflected wave. In this case, of course, the light emitting unit 200 does not emit light.

DESCRIPTION OF SYMBOLS 1 photoacoustic apparatus 120 receiving part 151 acquisition part 153 control part 200 light irradiation part

Claims (10)

A plurality of light irradiators for irradiating a subject with pulsed light;
A control unit configured to control the plurality of light irradiation units such that pulsed light is irradiated to the subject substantially simultaneously from the plurality of light irradiation units;
A receiving unit that receives an acoustic wave generated by irradiating the subject with pulsed light and converts the acoustic wave into an electrical signal;
An acquisition unit configured to acquire information on the subject based on the electrical signal;
A photoacoustic device having
The photoacoustic apparatus, wherein the control unit controls the light emitting unit such that pulse waveforms of pulse lights emitted from the plurality of light emitting units are different from each other.   The photoacoustic apparatus according to claim 1, wherein the control unit controls the light emitting unit such that pulse widths of pulse lights emitted from the plurality of light emitting units are different from each other. The photoacoustic apparatus according to claim 2, wherein the pulse width is 10 ns or more and 1 μs or less. The photoacoustic apparatus according to claim 3, wherein the pulse width is 100 ns or more and 800 ns or less.   The said control part controls the said light irradiation part as described in any one of the Claims 1 thru | or 4 so that the peak intensity of the pulsed light irradiated from these light irradiation parts may mutually differ. Photoacoustic device.   The photoacoustic apparatus according to any one of claims 1 to 5, wherein the light irradiation unit includes a light source unit that generates pulse light.   The photoacoustic apparatus according to claim 6, wherein the light source unit includes a plurality of semiconductor light emitting elements.   The photoacoustic apparatus according to claim 7, wherein the control unit controls peak intensity of the pulse light by controlling emission intensities of the plurality of semiconductor light emitting elements.   The photoacoustic apparatus according to claim 7, wherein the control unit controls the peak intensity of the pulse light by controlling the number of light emitting elements to be emitted among the plurality of semiconductor light emitting elements. The acquisition unit adds a plurality of electrical signals obtained based on an acoustic wave received by the plurality of light emitting units emitting light multiple times, and performs a process of dividing the sum by the number of times of light emission of the light emitting unit. The photoacoustic apparatus as described in any one of the Claims 1 thru | or 9 characterized by these.

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