JP6347698B2 - Photoacoustic probe and photoacoustic imaging apparatus - Google Patents

Description

  The present invention relates to a photoacoustic imaging apparatus, and more particularly to a photoacoustic imaging apparatus including a photoacoustic probe that detects an acoustic wave generated in a subject by light irradiation.

  Conventionally, ultrasonic imaging using transmission / reception of ultrasonic waves is known as a technique for acquiring a tomographic image of a subject (for example, a living body) without invasiveness. Furthermore, conventionally, photoacoustic imaging using photoacoustic waves (ultrasonic waves) generated inside a living body by irradiating the subject with light has been developed.

  In the photoacoustic imaging, since it is necessary to irradiate the inside of the subject with light, many of them use laser light having high light energy and high directivity. For example, as in Patent Document 1, laser light is incident on a light guide provided in the probe via an optical fiber. Then, laser light is irradiated from the light guide to the inside of the subject, and an elastic wave (photoacoustic wave) generated by adiabatic expansion inside the subject is detected by the laser light. The light guide unit is disposed adjacent to the acoustic wave detection unit that detects the photoacoustic wave, and the light guide unit is tilted so that the optical axis is directed to the central axis of the acoustic wave detection unit. The portion immediately below the probe inside the subject is irradiated with a light beam.

  In recent years, light emitting elements such as LEDs having high light energy have appeared, and a light source using the light emitting element instead of a laser light source has been proposed as a light source for the probe. The light emitting element has lower light energy than laser light. Therefore, when the light emitting element is used as a light source, the light energy is increased by using many light emitting elements.

  In addition, since the light emitting element has a light energy smaller than that of the laser light, the light emitting element is disposed adjacent to the subject in the vicinity of the acoustic wave detection unit, so that the light energy can be effectively utilized. It has become. By adopting such a configuration, the optical fiber and the light guide part are not used as in Patent Document 1, so that the probe can be miniaturized.

  Also when using the said light emitting element, it is preferable to arrange | position the said light emitting element so that an optical axis may go to the central axis of the said acoustic detection part similarly to patent document 1. FIG.

JP2013-233238A

  However, if the light emitting element is disposed at an inclination, an air layer is formed between the light emitting surface of the light emitting element and the subject, and light energy is attenuated. In the case of a light-emitting element with low light energy, the attenuation of light energy in the air layer, which was less affected by laser light with high light energy, is greatly affected, and accurate photoacoustic imaging may be difficult.

  Therefore, an object of the present invention is to provide a photoacoustic probe capable of improving operability by reducing power consumption and reducing the outer shape and detecting an accurate photoacoustic wave.

  It is another object of the present invention to provide a photoacoustic imaging apparatus that can create an accurate photoacoustic image.

  In order to achieve the above object, the present invention provides a light source unit that irradiates a subject with light, and a light source unit that is disposed adjacent to the light source unit and light from the light source unit is absorbed inside the subject. An acoustic wave detection unit for detecting the generated acoustic wave, wherein the light source unit has a plurality of light emitting elements, and a light guide unit having translucency and guiding light emitted from the light emitting elements to the subject. A light source holding unit for holding the light guide body so that optical axes of the plurality of light emitting elements are inclined toward a central axis of the acoustic wave detection unit; A contact portion including a surface in contact with the subject, and a reflection portion that reflects the light emitted from the light emitting element and the light reflected by the contact portion toward the subject.

  According to this configuration, it is possible to efficiently irradiate the subject with the light emitted from the light emitting element. Thus, high-accuracy photoacoustic imaging can be performed using a light-emitting element such as an LED that consumes less power than a laser that has been used as a light source and can be easily downsized.

  The said structure WHEREIN: The shape including the curved surface part curved in a convex shape with respect to the said contact part may be sufficient as the said reflection part provided near the said acoustic wave detection part. According to this configuration, it is possible to reliably irradiate the subject with light inside the light source unit without waste, and to reduce power consumption.

  The said structure WHEREIN: The circular arc may be sufficient as the cross-sectional shape of the said curved surface part.

  In the above configuration, the acoustic wave detection unit has a configuration in which a plurality of detection elements for detecting the photoacoustic wave are arranged, and the light emitting elements are arranged in the same direction as the arrangement direction of the detection elements. In addition, a partition portion provided to reflect light at both end portions in the arrangement direction of the light emitting elements may be provided.

  The partition may be a gap provided in the light guide, and a member that reflects light from the light emitting element may be provided in the gap.

  The plurality of light emitting elements may be mounted on the substrate in a predetermined arrangement, and the light source holding unit may hold the substrate so that a light emitting surface of the light emitting element faces the light source holding unit. .

In the above configuration, the angle of the inclination angle with respect to the contact portion of the portion of the reflecting portion that is first irradiated with the light that is emitted most widely from the light emitting element is a, and the optical axis of the light emitting element and the covered portion of the contact portion are When the angle with the normal of the surface in contact with the specimen is b, and the light distribution angle of the light emitting element is c,
When b + c / 2 <90 ° a = 120 ° − (b + c / 2)
Or when b + c / 2 ≧ 90 °, a = 160 ° − (b + c / 2)
(However, 0 <b ≦ 40 °, 60 ° ≦ c ≦ 160 °)
The light guide satisfying the above can be mentioned.

In the above configuration, when the refractive index of the subject is n1 and the refractive index of the light guide is n2,
Sin ^-1 (n1 / n2) ≧ 60 °
The material of the light guide satisfying the above may be used.

  In the above configuration, the light emitting element may include at least one of a light emitting diode element, a semiconductor laser element, and an organic light emitting diode element.

  As an apparatus provided with the above-mentioned photoacoustic probe, a photoacoustic imaging apparatus that images an internal state of the subject based on information from the photoacoustic probe can be cited.

  According to the present invention, it is possible to provide a photoacoustic probe that can improve operability by reducing the outer shape with low power consumption and can detect an accurate photoacoustic wave.

  Further, according to the present invention, it is possible to provide a photoacoustic imaging apparatus capable of creating an accurate photoacoustic image.

1 is a schematic external view of an example of a photoacoustic imaging apparatus according to the present invention. It is a block diagram of the photoacoustic imaging device shown in FIG. It is a schematic perspective view of the photoacoustic probe concerning this invention. It is a disassembled perspective view of the light source part with which the photoacoustic probe concerning this invention is equipped. It is the schematic of the light source board provided with the LED element. It is a perspective view of the light source cover bottom with which a light source part is equipped. It is a bottom view of the light source cover bottom shown in FIG. It is sectional drawing cut | disconnected by the VIII-VIII line | wire of the light source cover bottom shown in FIG. It is sectional drawing which cut | disconnected the light source cover bottom shown in FIG. 7 by the IX-IX line. It is a figure which shows the optical path in the light source cover bottom used for the light source part concerning this invention. It is a bottom view of the other example of the photoacoustic probe concerning this invention. It is sectional drawing to which the partition part of the light source cover bottom shown in FIG. 11 was expanded.

  A photoacoustic imaging apparatus according to the present invention will be described with reference to the drawings.

  FIG. 1 is a schematic external view of an example of a photoacoustic imaging apparatus according to the present invention, and FIG. 2 is a block diagram of the photoacoustic imaging apparatus shown in FIG.

  The photoacoustic imaging apparatus A according to the present invention irradiates light having a wavelength with a small attenuation inside the subject Bd (for example, about 650 nm to about 1100 nm in the case of a living body), and the internal tissue emits light energy. A tomographic image is obtained by detecting an elastic wave (ultrasonic wave) due to absorption and thermal expansion.

  As shown in FIGS. 1 and 2, the photoacoustic imaging apparatus A includes a photoacoustic probe 10 that irradiates a subject Bd that is a living body and detects a photoacoustic wave generated in the subject Bd. An image generation unit 20 that generates a photoacoustic image based on a photoacoustic wave detection signal is provided. In addition, the photoacoustic probe 10 transmits ultrasonic waves to the subject Bd and also detects ultrasonic waves that are reflected waves, and the image generation unit 20 generates an ultrasonic image based on the ultrasonic detection signal. Also generate. Furthermore, the photoacoustic imaging apparatus A also includes an image display unit 30 that displays an image based on the image signal generated by the image generation unit 20.

  The photoacoustic probe 10 includes a drive power supply unit 11, a light source unit 13 that emits light (infrared light: wavelength of about 850 nm) when power is supplied from the drive power supply unit 11, and a light emitting element provided in the light source unit 13. LED driving circuit 12 for controlling the above.

  Here, details of the photoacoustic probe 10 will be described with reference to a new drawing. FIG. 3 is a schematic perspective view of the photoacoustic probe. In the following description, as shown in FIG. 3, the arrangement direction of the acoustoelectric transducers 141 of the acoustic wave detection unit 14 is the X direction, the direction orthogonal to the arrangement direction is the Y direction, and the vertical direction on the paper is the Z direction.

  As shown in FIG. 3, the photoacoustic probe 10 includes an acoustic wave detection unit 14 and a light source unit 13 that is disposed in proximity to the acoustic wave detection unit 14. The photoacoustic probe 10 makes the lower side in the Z direction in FIG. 3 contact the subject Bd, and irradiates the subject Bd with light from the light source unit 13 or irradiates the subject with ultrasonic waves from the acoustic wave detection unit 14. An acoustic wave from the inside of the specimen Bd is detected.

  The acoustic wave detection unit 14 has a configuration in which acoustoelectric conversion elements 141 that transmit or detect ultrasonic waves are arranged in the X direction. The acoustic wave detection unit 14 has the same configuration as that of an ultrasonic probe used in a conventional ultrasonic tomographic diagnosis apparatus, and thus detailed description thereof is omitted.

  As shown in FIG. 3, the photoacoustic probe 10 includes two light source units 13. The two light source units 13 are long members extending in the arrangement direction (that is, the X direction) of the acoustoelectric conversion elements 141. Further, the two light source units 13 are arranged so as to sandwich the acoustic wave detection unit 14 from both sides in the Y direction. The light source unit 13 irradiates the subject Bd with planar light whose in-plane luminance is equalized. Thereby, uniform or substantially uniform light can be irradiated to the lower part of the acoustic wave detection part 14 in the Z-axis direction.

  The light emitted from the light source unit 13 enters the subject Bd while being scattered, and is absorbed by the light absorber (biological tissue) in the subject Bd. When the light absorber absorbs light, a photoacoustic wave (ultrasonic wave) that is an elastic wave is generated by adiabatic expansion. The generated photoacoustic wave propagates in the subject Bd and is converted into a voltage signal by the acoustoelectric conversion element 141. The acoustoelectric conversion element 141 of the acoustic detection unit 14 may generate an ultrasonic wave, send the ultrasonic wave into the subject Bd, receive the ultrasonic wave reflected in the subject Bd, and generate a voltage signal. Is possible. That is, the photoacoustic imaging apparatus A of the present embodiment can also perform ultrasonic imaging in addition to photoacoustic imaging.

  The acoustic wave (ultrasonic wave) used in the photoacoustic imaging apparatus A is greatly attenuated when propagating through the air layer. Therefore, the photoacoustic imaging apparatus A may use an acoustic matching fluid (gel) that matches the acoustic impedance between the acoustic wave detection unit 14 and the subject Bd. By applying this gel, the acoustic wave detection characteristics can be improved, and the LED element 131 of the light source unit 13 can be cooled.

  Next, the image generation unit 20 will be described. As shown in FIG. 2, the image generation unit 20 includes a reception circuit 21, an A / D converter 22, a reception memory 23, a data processing unit 24, a photoacoustic image reconstruction unit 25, a detection / logarithmic converter 26, and a photoacoustic image construction. 27, an ultrasonic image reconstruction unit 28, a detection / logarithmic converter 29, an ultrasonic image construction unit 210, an image composition unit 211, a control unit 212, and a transmission control circuit 213.

  The receiving circuit 21 selects some of the acoustoelectric transducers 141 from the plurality of acoustoelectric transducers 141 and performs a process of amplifying a voltage signal (detection signal) for the selected acoustoelectric transducers 141.

  In the case of photoacoustic imaging, for example, the plurality of acoustoelectric transducers 141 are divided into two areas adjacent in the X direction, and one area is selected for the first light irradiation, and the second light irradiation is performed. The remaining one area is selected at the time. In the case of ultrasonic imaging, for example, an ultrasonic wave is generated while switching a group of a plurality of adjacent acoustoelectric transducers 141 among a plurality of acoustoelectric transducers 141 (so-called linear electronic scan), and a receiving circuit. 21 also selects the group while switching.

  The A / D converter 22 converts the amplified detection signal from the reception circuit 21 into a digital signal. The reception memory 23 stores the digital signal from the A / D converter 22. The data processing unit 24 has a function of distributing the signal stored in the reception memory 23 to the photoacoustic image reconstruction unit 25 or the ultrasonic image reconstruction unit 28.

  The photoacoustic image reconstruction unit 25 performs phase matching addition processing based on the photoacoustic wave detection signal to reconstruct the photoacoustic wave data. The detection / logarithmic converter 26 performs logarithmic compression processing and envelope detection processing on the reconstructed photoacoustic wave data. Then, the photoacoustic image construction unit 27 converts the data processed by the detection / logarithmic converter 26 into luminance value data for each pixel.

  On the other hand, the ultrasonic image reconstruction unit 28 performs phase matching addition processing based on the ultrasonic detection signal to reconstruct the ultrasonic data. The detection / logarithmic converter 29 performs logarithmic compression processing and envelope detection processing on the reconstructed ultrasonic data. Then, the ultrasonic image construction unit 210 converts the data processed by the detection / logarithmic converter 29 into luminance value data for each pixel.

  The image synthesizing unit 211 synthesizes the photoacoustic image data and the ultrasonic image data to generate synthesized image data. Here, for image synthesis, a photoacoustic image may be superimposed on an ultrasonic image, or a photoacoustic image and an ultrasonic image may be arranged in parallel. The image display unit 30 displays an image based on the combined image data generated by the image combining unit 211.

  Note that the image composition unit 211 may output either photoacoustic image data or ultrasonic image data to the image display unit 30 as it is.

  In addition, the control unit 212 transmits a wavelength control signal to the LED drive circuit 12, and the LED drive circuit 12 that has received the wavelength control signal transmits the light trigger signal from the control unit 212 to the light source drive circuit 102. The drive circuit 12 transmits a drive signal to the LED element 131.

  Further, the transmission control circuit 213 transmits a drive signal to the acoustoelectric conversion element 141 in accordance with an instruction from the control unit 212 to generate an ultrasonic wave. Note that the control unit 212 also controls the receiving circuit 21 and the like.

(First embodiment)
Next, details of the light source unit 13 which is a main part of the photoacoustic probe 10 according to the present invention will be described with reference to the drawings. FIG. 4 is an exploded perspective view of a light source unit provided in the photoacoustic probe according to the present invention, and FIG. 5 is a schematic view of a light source substrate provided with LED elements. 6 is a perspective view of a light source cover bottom provided in the light source unit, and FIG. 7 is a bottom view of the light source cover bottom shown in FIG. FIG. 8 is a cross-sectional view taken along line VIII-VIII of the light source cover bottom shown in FIG. 7, and FIG. 9 is a cross-sectional view taken along line IX-IX of the light source cover bottom shown in FIG. 8 and 9 are cross-sectional views, but hatching indicating the cross-section is omitted.

  The photoacoustic probe 10 includes two light source units 13, which have substantially the same configuration, and therefore, one of them will be illustrated and described as a representative.

  As shown in FIG. 4, the light source unit 13 includes a light source substrate 130, a light source cover bottom 15 (light guide), and a light source cover top 16. The light source cover bottom 15 has an open top surface, and is configured to close the opening of the light source cover bottom 15 with a light source cover top 16 having a rectangular plate shape. The light source cover bottom 15 and the light source cover top 16 constitute the exterior of the light source unit 13.

  The light source substrate 130 is a wiring substrate having a wiring pattern formed on the surface thereof. As shown in FIG. 5, LED elements 131, which are light emitting elements, are mounted on the surface of the light source substrate 130 in a two-dimensional array so as to be equally spaced in the vertical and horizontal directions. The LED elements 131 may be arranged in a staggered manner. The light source substrate 130 is connected to the LED drive circuit 12, receives a drive signal from the LED drive circuit 12, and the LED element 131 emits pulsed light based on the drive signal. In the light source unit 13, the LED elements 131 are mounted in a two-dimensional array on the light source substrate 130 to emit planar light with a constant luminous flux. The LED element 131 is an element that irradiates light having a wavelength (here, about 850 nm) that easily penetrates into the living body.

  The light source cover bottom 15 includes a substrate support portion 151 (substrate holding portion), a concave portion 152, a light incident surface 153, and a reflection portion 154 (curved surface portion). Further, the light source cover bottom 15 includes a contact portion 150 that comes into contact with the subject Bd when the photoacoustic probe 10 detects tomographic image information. The light source cover bottom 15 is a holding member that holds the light source substrate 130 on which the LED element 131 is mounted, and is also a light guide member that guides light emitted from the LED element 131 to the subject Bd. Therefore, the light guide part 155 formed with the translucent material which permeate | transmits the light radiate | emitted from the LED element 131 is provided (refer FIG. 8 etc.). In addition, as a translucent material which comprises the light guide part 155, although an acryl, a polycarbonate, etc. can be mentioned, for example, it is not limited to this. Further, the entire light source cover bottom 15 may be formed of a translucent material.

  The substrate support portion 151 has a pair of support surfaces that support both ends of the light source substrate 130 in the longitudinal direction. The substrate support unit 151 is formed so that the optical axis of the LED light source 131 is inclined toward the reflection unit 154, that is, the photoacoustic detection unit 14 when the light source substrate 130 is disposed on the upper surface.

  The recess 152 is formed between the pair of substrate support portions 151. When the light source substrate 130 is arranged so that the LED element 131 faces the light source cover bottom 15, the LED element 131 is accommodated. The light incident surface 153 is formed on the bottom surface of the recess 152, and is disposed so that the light emitting surface (not shown) of the LED element 131 is opposed. More specifically, when the light source substrate 130 is disposed on the upper surfaces of the pair of substrate support portions 151, the light incident surface 153 is formed so that the optical axes of the LED elements 131 are orthogonal to each other. The light emitting surface of the LED element 131 is disposed in contact with or close to the light incident surface 153 so that the light from the LED element 131 can be efficiently incident on the light incident surface.

  Further, the longitudinal range of the light incident surface 153 is formed so as to coincide with or substantially coincide with the range in which the acoustoelectric transducers 141 of the acoustic wave detection unit 14 are arranged. Thereby, since the light from the light source part 13 is correctly irradiated to the part directly under the range where the acoustoelectric transducers 141 of the subject Bd are arranged, it is possible to acquire accurate tomographic image information. is there.

  In the light source cover bottom 15, the light incident from the light incident surface 153 passes through the light guide unit 155 and is irradiated from the contact unit 150 to the subject Bd. In order to allow light to efficiently enter the light incident surface 153 from the LED element 131, the light incident surface 153 is provided with an AR (Anti-Reflection) coat that suppresses reflection. Note that the AR coating may be omitted when light can be efficiently incident from the LED element 131 to the light incident surface 153. The light incident surface 153 may be provided with an optical element that diffuses incident light or polarizes it into parallel light.

  The reflection unit 154 is disposed in proximity to a portion of the acoustic wave detection unit 14 that contacts the subject Bd. Therefore, the reflecting portion 154 has a curved surface shape obtained by cutting a cylindrical shape having a certain curvature in the circumferential direction, and has a shape such that the tip portion is close to the acoustoelectric conversion element 141 of the acoustic wave detecting portion 14. Yes. That is, as shown in FIG. 9, the reflecting portion 154 has a curved surface shape that becomes a convex surface on the light guide portion 155 side.

  Since the light guide unit 155 has a higher refractive index than air or the subject Bd, when light is irradiated from the inside of the light guide unit 155 to the outer surface, the incident angle is greater than the critical angle. The reflected light is totally reflected. And since the LED element 131 is a point light source, it irradiates the light which diffuses by the spread of a fixed angle (it is set as a light distribution angle). The light that has entered the light guide 155 from the light incident surface 153 is also diffused in the same manner. Since the optical axis of the LED element 131 is inclined toward the reflecting portion 154 side of the light emitting substrate 130, the light that is directly incident on the contact portion 150 with light spreading to the opposite side of the reflecting portion 154 is smaller than the critical angle. In many cases, the incident angle is reached, and the subject Bd is efficiently irradiated.

  When the light incident from the light incident surface 153 or the light totally reflected by the contact part 150 enters the reflective part 154, the light may be emitted from the reflective part 154 to the outside, and the output of the LED element 130 is wasted. . Therefore, in the light source unit 13, a reflective film made of a material (metal) having a high reflectance such as aluminum or gold is formed on the outer surface of the reflecting unit 154. As a result, all or substantially all of the light incident on the reflecting portion 154 is reflected toward the light guiding portion 155 regardless of the incident angle. The light incident on the reflective portion 154 is reflected toward the contact portion 150 because the reflective portion 154 is convex toward the light guide portion 155. Thereby, the light emitted from the LED element 131 can be efficiently irradiated onto the subject Bd, and the light irradiation efficiency can be increased. Details of the shapes of the incident surface 153 and the reflecting portion 154 will be described later.

  In the light source cover bottom 15, the range of the light guide 155 in the longitudinal direction is the range where the light incident surface 153 is formed. The light incident from the light incident surface 153 is also diffused in the longitudinal direction (X direction) of the light source cover bottom 15. The acoustic wave detection unit 14 preferably detects an acoustic wave from directly below a portion where the acoustoelectric conversion elements 141 are arranged. However, when light diffused in the longitudinal direction from the light source unit 13 is irradiated, an acoustic wave from a position shifted from the acoustoelectric conversion element 141 may be incident. Therefore, the partition part 17 which reflects light is provided in the edge part of the longitudinal direction (X direction) of the light guide part 155 among the lights radiate | emitted from the LED element 131. As shown in FIG.

  As shown in FIGS. 7 and 9, the partitioning portion 17 has a configuration in which a member formed of a material having a high reflectance is embedded in the light source cover bottom 15. By providing such a partitioning part 17, it is possible to prevent light from being irradiated outside the lower part of the range where the acoustoelectric conversion elements 141 of the acoustic wave detecting part 14 of the subject Bd are arranged. it can. In addition, when the LED element 131 itself has a configuration in which light does not diffuse in the longitudinal direction of the light source cover bottom 15, the partition portion 17 may be omitted.

  The light source cover top 16 is attached so as to close the opening of the light source cover bottom 15. In the light source cover top 16, a wiring 4 for supplying a control signal and driving power to the LED element 131 mounted on the light source substrate 130 from the LED driving circuit 12 penetrates. When the light source cover top 16 is attached so as to close the opening of the light source cover bottom 15, the light source substrate 130 is pressed so as not to be displaced.

  Next, the detailed shape of the light source cover bottom 15 of the light source unit 13 according to the present invention will be described. FIG. 10 is a view showing an optical path in the light source cover bottom used in the light source section according to the present invention.

  The light emitted to the outermost side of the light emitted from the LED element 131 is the light emitted from the LED element 131 closest to the reflective portion 154 to the reflective portion 154 side when the light source substrate 130 is disposed on the substrate support portion 151. (Here, it is referred to as light Ph1). The shape of the reflecting portion 154 is such that the light Ph1 is reflected so as to be incident on the contact surface 150 at an incident angle equal to or smaller than the critical angle, so that the light from the LED element 131 is reliably transmitted from the contact surface 150 to the subject Bd. Can be irradiated.

Therefore, as a result of intensive studies, the present inventor has found that the following conditions are satisfied for the shape of the reflecting surface 154. The angle between the tangent line and the contact surface 150 at which the light Ph1 of the reflecting portion 154 is irradiated is the angle a, the tilt angle of the light incident surface 153 with respect to the contact surface 150 is the angle b, and the light distribution angle of the LED element 131 is the angle c. As for the angle a, the angle b, and the angle c, the following expressions hold.
When b + c / 2 <90 ° a = 120 ° − (b + c / 2)
Or
When b + c / 2 ≧ 90 ° a = 160 ° − (b + c / 2)
However, 0 <b ≦ 40 ° and 60 ° ≦ c ≦ 160 °.

By determining the shape of the reflecting portion 154 so as to satisfy the above conditions, the angle at which the light reflected by the reflecting portion 154 enters the contact surface 150 can be set to 60 degrees or less. And by satisfy | filling the following formula | equation, the light reflected by the reflection part 154 can be irradiated in a subject, without being totally reflected by the contact surface 150. FIG.
Sin ^-1 (n1 / n2) ≧ 60 °
n1 is the refractive index of the subject, n2 is the refractive index of the light guide

  It is possible to suppress light incident on the inside of the light guide unit 155 from being attenuated inside the light guide unit 155 by repeating total reflection or being emitted outside from the contact surface 150 that contacts the subject Bd. it can. Thereby, the utilization efficiency of the light radiate | emitted from the LED element 131 can be improved, and tomographic image information can be detected efficiently.

(Second Embodiment)
Another example of the photoacoustic probe according to the present invention will be described with reference to the drawings. FIG. 11 is a bottom view of another example of the photoacoustic probe according to the present invention, and FIG. 12 is an enlarged cross-sectional view of the partition portion of the light source cover bottom shown in FIG. The light source cover bottom 13b shown in FIG. 12 has the same configuration as the light source cover bottom 13 except that the configuration of the partitioning portion 158 is different and includes the light source cover bottom 15b. Therefore, substantially the same parts are denoted by the same reference numerals, and detailed description of the same parts is omitted. Moreover, since the structure of the photoacoustic probe 10 other than the light source part 13b is the same structure as 1st Embodiment, detailed description is abbreviate | omitted.

  As shown in FIGS. 11 and 12, the light source cover bottom 15 b has a partition 158 formed on the contact surface 150. The partition portion 158 is provided with a concave portion 1581 having an opening on the contact surface 150 side. A surface perpendicular to the contact surface 150 is provided on the light source substrate 130 side of the recess 1581. A reflective film made of a highly reflective material (metal) such as aluminum or gold is formed on the vertical surface from the outside.

  Thus, manufacture is easy by forming the concave portion 1581 and forming the reflective film on the outer surface thereof. Other features are the same as in the first embodiment.

  In each said embodiment, although the LED element is utilized as a light emitting element, it is not limited to this. A small element such as a light-emitting diode element, a semiconductor laser element, or an organic light-emitting diode element that can be easily controlled in light emission can be widely used. In addition, although a plurality of LED elements are mounted side by side on the light emitting substrate, the present invention is not limited to this, and may be directly arranged on a part of the constituent members of the light emitting unit.

  As mentioned above, although embodiment of this invention was described, this invention is not limited to this content. The embodiments of the present invention can be variously modified without departing from the spirit of the invention. Further, the above embodiments can be implemented in combination as appropriate.

A Photoacoustic imaging apparatus 10 Photoacoustic probe 11 Drive power supply unit 12 LED drive circuit 13 Light source unit 130 Light source substrate 131 LED element (light emitting element)
14 Acoustic wave detection unit 15 Light source cover bottom 151 Substrate support unit (substrate holding unit)
152 Concave part 153 Light entrance surface 154 Reflector 155 Light guide part 16 Light source cover top 20 Image generation part 21 Reception circuit 22 A / D converter 23 Reception memory 24 Data processing part 25 Photoacoustic image reconstruction part 26 Detection / logarithmic converter 27 Light Acoustic image construction unit 28 Ultrasonic image reconstruction unit 29 Detection / logarithmic converter 210 Ultrasonic image construction unit 211 Image composition unit 212 Control unit 213 Transmission control circuit 30 Image display unit 4 Wiring

Claims (12)

A light source unit that emits light to the subject;
An acoustic wave detection unit that is disposed adjacent to the light source unit and detects an acoustic wave generated when light from the light source unit is absorbed inside the subject;
The light source unit includes a plurality of light emitting elements, and a light guide having translucency and guiding light emitted from the light emitting elements to the subject,
The light guide includes: a light source holding unit that holds an optical axis of the plurality of light emitting elements so as to be inclined toward a central axis of the acoustic wave detection unit; a contact unit that includes a surface that contacts the subject; A photoacoustic probe comprising: a light reflecting portion that reflects light emitted from a light emitting element and light reflected by the contact portion toward the subject.   2. The photoacoustic probe according to claim 1, wherein the reflection part is provided in proximity to the acoustic wave detection part, and the reflection part includes a curved surface part that curves in a convex shape with respect to the contact part. Child.   The photoacoustic probe according to claim 2, wherein a cross-sectional shape of the curved surface portion is an arc. The acoustic wave detection unit has a configuration in which a plurality of detection elements for detecting the photoacoustic wave are arranged,
The light emitting elements are arranged side by side in the same direction as the arrangement direction of the detection elements,
The photoacoustic probe according to any one of claims 1 to 3, further comprising a partition portion provided so as to reflect light at both end portions in the arrangement direction of the light emitting elements. The partition is a gap provided inside the light guide,
The photoacoustic probe according to claim 4, wherein a member that reflects light from the light emitting element is provided inside the gap. The plurality of light emitting elements are mounted on the substrate in a predetermined arrangement,
The photoacoustic probe according to any one of claims 1 to 5, wherein the light source holding unit holds the substrate such that a light emitting surface of the light emitting element faces the light source holding unit. The angle of the inclination angle with respect to the contact portion of the portion where the light that is emitted from the light emitting element of the reflecting portion and is most spread is first irradiated is a, and the optical axis of the light emitting element is in contact with the subject at the contact portion. When the angle with the normal of the surface is b, and the light distribution angle of the light emitting element is c,
When b + c / 2 <90 ° a = 120 ° − (b + c / 2)
Or when b + c / 2 ≧ 90 °, a = 160 ° − (b + c / 2)
(However, 0 <b ≦ 40 °, 60 ° ≦ c ≦ 160 °)
The photoacoustic probe according to claim 1, wherein the light guide is formed so as to satisfy the above. The light guide is
When the refractive index of the subject is n1, and the refractive index of the light guide is n2,
Sin ^-1 (n1 / n2) ≧ 60 °
The photoacoustic probe according to claim 7, wherein the photoacoustic probe is made of a material that satisfies the above requirements.   The photoacoustic probe according to claim 1, wherein the light emitting element includes a light emitting diode element.   The photoacoustic probe according to claim 1, wherein the light emitting element includes a semiconductor laser element.   The photoacoustic probe according to claim 1, wherein the light emitting element includes an organic light emitting diode element. A photoacoustic probe according to any one of claims 1 to 11, comprising:
A photoacoustic imaging apparatus that images an internal state of the subject based on information from the photoacoustic probe.

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