JP2016097165A - Subject information acquisition device and probe - Google Patents

Abstract

PROBLEM TO BE SOLVED: To control light radiation density of a photoacoustic apparatus, and improve safety property.SOLUTION: A subject information acquisition device comprises: a light source for generating light; an optical system for transmitting light; an injection part for injecting light which has been transmitted by the optical system; a reception part for receiving an acoustic wave generated from a subject to which light is radiated, and outputting an electric signal; and a processing part for using the electric signal for acquiring information of inside of the subject. The injection part comprises a diffusion mechanism for, reducing radiation density on a position separated from the light radiation position by 14 cm, to equal to or less than 0.5% of radiation density on the light radiation position of the injection part.SELECTED DRAWING: Figure 5

Description

  The present invention relates to an object information acquisition apparatus and a probe.

  Photoacoustic tomography (hereinafter referred to as PAT) has attracted attention as a method for specifically imaging angiogenesis caused by cancer. PAT is a technique for receiving a photoacoustic wave generated from the inside of the subject by the photoacoustic effect when light is irradiated on the subject and imaging it.

  In a photoacoustic apparatus using PAT, a bundle fiber may be used for light transmission from a light source to an emission end. Such an optical transmission system is suitable for a handheld photoacoustic apparatus having a housing including a probe and an emission end, and an engineer holding the housing in his hand and pressing it against a subject. . However, since the bundle fiber is obtained by processing fiber strands of about 200 μm into a bundle shape, the light emitted from each fiber interferes with each other, and the energy density may locally increase.

  Here, when irradiating light (particularly laser light) to the human body, a maximum permissible exposure (MPE: maximum permissible exposure) is defined as a safety standard (ANSI Z136.1-2000). The MPE is determined according to the wavelength and according to each part of the skin and the eye, and the eye has a lower MPE value than the skin. And when the photoacoustic apparatus using a bundle fiber irradiates light on the skin surface, when the energy density is increasing locally as described above, it may exceed the MPE for the skin.

  Even when the amount of light is less than or equal to the MPE for the skin, if the light enters the eyes, the value of the MPE for the eyes may be exceeded. For example, in the case of the hand-held type, there is a possibility that an engineer's hand with a body moves and light is emitted into the air, and enters the eyes of the engineer or the subject. In addition, even with a photoacoustic device with a fixed exit end where the subject lies on a bed-like support member, the MPE for the eyes can be exceeded if the technician or the subject looks into the exit end. There is sex.

  Patent Document 1 discloses a technique for ensuring the optical path length by passing light emitted from a bundle fiber through a diffusion plate and further arranging a spacer. Thereby, energy irradiation is made uniform, a local increase in energy density is prevented, and safety for the skin in particular is improved.

Japanese Patent Application Laid-Open No. 2014-083196

  In Patent Document 1, although the irradiation density distribution on the surface of the subject can be controlled by using a diffusion plate and the energy density on the surface of the subject can be made uniform, the irradiation density distribution when light is emitted into the space is considered. It wasn't. When light is emitted without the probe being in contact with the subject, the light is emitted into the air at a narrow diffusion angle of about 10 degrees. This is because the emission angle of the emitted light is limited by a physical arrangement in which there is a spacer between the diffusion plate and the subject. As a result, there is a possibility that light with a high energy density may reach an object (for example, an eye of a technician or a subject) located at a distant position.

  This invention is made | formed in view of the above subjects, The objective is to control the irradiation density of the light of a photoacoustic apparatus, and to improve safety | security.

The present invention employs the following configuration. That is,
A light source that generates light;
An optical system that propagates the light;
An emission part for emitting the light propagated through the optical system;
A receiving unit that receives an acoustic wave generated from the subject irradiated with the light and outputs an electrical signal; and
A processing unit for acquiring information inside the subject using the electrical signal;
Have
The emission part has a diffusion mechanism that reduces the irradiation density at a position 14 cm away from the light irradiation position in air to 0.5% or less of the irradiation density at the light irradiation position of the emission part. This is a subject information acquisition apparatus.

The present invention also employs the following configuration. That is,
An emission unit for emitting light to irradiate the subject;
A receiver that receives an acoustic wave generated from the subject irradiated with the light;
Have
The emission part has a diffusion mechanism that reduces the irradiation density at a position 14 cm away from the light irradiation position in air to 0.5% or less of the irradiation density at the light irradiation position of the emission part. It is a handheld probe.

  ADVANTAGE OF THE INVENTION According to this invention, the irradiation density of the light of a photoacoustic apparatus can be controlled and safety can be improved.

The figure explaining an apparatus structure. The figure explaining the structure of a photoacoustic probe. The figure explaining light emission of a photoacoustic probe. The figure explaining an example of a light-diffusion mechanism. The figure explaining an example of a shielding mechanism. FIG. 3 is a diagram illustrating light attenuation in the first embodiment. FIG. 3 is a diagram illustrating light attenuation in the first embodiment. FIG. 6 is a diagram for explaining light attenuation in the second embodiment. FIG. 6 is a diagram for explaining a scattering angle and light attenuation in the second embodiment. FIG. 10 is a diagram illustrating a probe configuration in Example 4. FIG. 10 is a diagram illustrating a probe configuration in Example 5.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. However, the dimensions, materials, shapes, and relative arrangements of the components described below should be changed as appropriate according to the configuration of the apparatus to which the invention is applied and various conditions. It is not intended to limit the following description.

  The present invention relates to a technique for detecting acoustic waves propagating from a subject, generating characteristic information inside the subject, and acquiring the characteristic information. Therefore, the present invention can be understood as a subject information acquisition apparatus or a control method thereof, a subject information acquisition method, or a signal processing method. The present invention can also be understood as a program that causes an information processing apparatus including hardware resources such as a CPU to execute these methods, and a storage medium that stores the program. The present invention can also be understood as an acoustic wave measuring device and a control method thereof.

  The subject information acquiring apparatus of the present invention irradiates a subject with light (electromagnetic waves) and receives (detects) an acoustic wave generated and propagated in the subject or on the subject surface according to the photoacoustic effect. Includes equipment that uses graphic technology. Such an object information acquisition apparatus obtains characteristic information inside the object in the form of image data or the like based on photoacoustic measurement, and thus can be called a photoacoustic tomography apparatus, a photoacoustic image apparatus, or simply a photoacoustic apparatus. .

  Characteristic information in the photoacoustic device is composed of the source distribution of acoustic waves generated by light irradiation, the initial sound pressure distribution in the subject, or the optical energy absorption density distribution, absorption coefficient distribution, and tissue derived from the initial sound pressure distribution. Concentration distribution of substances to be included. Specifically, it is a blood component distribution such as an oxygenated / reduced hemoglobin concentration distribution, an oxygen saturation distribution obtained therefrom, or a distribution of fat, collagen, and water. Further, the characteristic information may be obtained as distribution information of each position in the subject, not as numerical data. That is, distribution information such as an absorption coefficient distribution and an oxygen saturation distribution may be used as the subject information.

The acoustic wave referred to in the present invention is typically an ultrasonic wave and includes an elastic wave called a sound wave or an acoustic wave. An acoustic wave generated by the photoacoustic effect is called a photoacoustic wave or an optical ultrasonic wave. An electrical signal converted from an acoustic wave by the probe is also called an acoustic signal, and an acoustic signal derived from the photoacoustic wave is particularly called a photoacoustic signal.
As a subject in the present invention, a living body breast or skin can be assumed. However, the subject is not limited to this, and other parts of the living body and non-biological materials can be measured.

[Device configuration and functions]
The present invention is based on the principle of reducing the energy density after light emission over a short distance by diffusing light. As a result, light passing through the air or the like becomes lower than MPE (particularly the value for the eyes), and safety is improved.

  An example of the embodiment of the photoacoustic apparatus will be described with reference to FIG. The apparatus includes a photoacoustic probe 1 including a probe 2 and an emission unit 8, a light source 4, an optical system 5, a processing device 6, and a monitor 7.

  The light source 4 generates near infrared rays. As the light source 4, a pulse laser having a wavelength of 700 nm to 900 nm can be used. Specifically, a pulsed laser such as an Nd: YAG laser or an Alexandrite laser is suitable. In addition, a Ti: sa laser or an OPO laser using Nd: YAG laser light as excitation light may be used. In the case of a flash lamp, an LED light source, etc., there are situations where the amount of light incident on the eye should be reduced depending on the light intensity and convergence. Therefore, these light sources can also be applied to the present invention.

  The optical system 5 forms a beam of light and propagates it to the exit end to the subject. The bundle fiber 3 is a member that propagates light, and may be included in the optical system 5. In the example of FIG. 1, the light irradiation end of the emission portion 8 is the emission end. For propagation of light, an optical member such as a combined structure of a light shielding tube and a mirror may be used instead of the bundle fiber 3 or together with the bundle fiber 3.

The photoacoustic probe 1 includes a probe 2 that receives a photoacoustic wave emitted from a subject and an emission unit 8. The probe 2 is an acoustic wave receiving unit including at least one receiving element that converts a photoacoustic wave into an analog electric signal. In the case of a hand-held photoacoustic apparatus, the photoacoustic probe 1 is usually held in a housing that can be grasped by a hand such as a doctor or an inspection engineer. Furthermore, it is preferable that the photoacoustic probe 1 can be exchanged according to the depth inside the subject to be measured, the substance to be measured, the surface shape of the subject, and the subject size. When exchanging, it is conceivable that only the probe 2 is exchanged according to conditions (for example, the center frequency of the receiving element), or the entire emitting unit 8 is exchanged. Moreover, you may provide the connection part which can replace | exchange the whole housing.

  The device branches part of the light and directs it to a photodiode (not shown). When the photodiode detects light, it outputs a trigger signal (TRG). The trigger signal generation means is not limited to the photodiode, and a method of synchronizing the light emission of the light source 4 and the input trigger to the processing device 6 with a signal generator may be used.

The processing device 6 is a processing unit that includes an information processing device that includes a CPU, a storage unit, and the like and operates according to a program, and a signal processing device that processes electrical signals. The processing device 6 receives the electrical signal output from the probe 2 via the cable 40. Each function of the processing device may be realized by a separate circuit or device. One of the functions of the processing device 6 is to perform signal processing such as amplification, AD conversion, detection, and correction on an analog electric signal derived from a photoacoustic wave as necessary to create a digital electric signal. . Another function of the processing device 6 is to generate image information (IMG) based on characteristic information inside the subject based on the digital electrical signal. For generating image information, a known method such as phasing addition can be used. The trigger signal is used as a trigger for receiving a photoacoustic wave by the probe 2.
The monitor 7 displays characteristic information based on the image information. In addition to images, numerical information, graphics, symbols, etc. may be displayed.

  The structure of the photoacoustic probe 1 in the present invention is shown in FIG. In FIG. 2, the casing is omitted. The emitting unit 8 includes a member 30 that covers at least the tip 3 a of the bundle fiber 3, and a light diffusion mechanism 9 provided at the tip 3 a of the bundle fiber 3. As shown in FIG. 3, the laser light emitted from the fiber tip 3 a is scattered and diffused to some extent by the light diffusion mechanism 9. By randomizing the light emission direction in this way, when light is emitted in a state where the probe 1 is separated from the subject 10, the attenuation amount of the light irradiation density in the air increases. On the other hand, if the probe 1 is in contact with the surface of the subject 10, since there is no structure such as a spacer between the light diffusion mechanism 9 and the subject 10, most of the scattered light eventually becomes the subject. The surface of the specimen 10 can be reached. As a result, the irradiation density is kept high, and a photoacoustic image with high contrast is obtained.

  With such a probe configuration, even if light is unintentionally irradiated on a subject other than the subject, the light irradiation density via the space can be suppressed, so that safety is improved. In order to ensure multiple safety, it is preferable that at least the engineer and the subject wear laser safety goggles and install a light shielding curtain between the subject's eyes and the photoacoustic probe 1.

  From the viewpoint of reducing the amount of light in front of the emission end 8a as much as possible, the scattering angle of the scattered light 11 is preferably as large as possible. More specifically, the scattering angle is determined by the handling when the engineer holds the probe, the distance from the eye of the engineer or the subject to the probe, the amount of light incident on the subject, and the like. As a typical case, when an engineer performs a procedure using the handheld photoacoustic probe 1, the distance between the ejection end 8a of the ejection portion 8 and the eye is determined by the length of the upper arm and the bending angle of the elbow. Therefore, even when the distance between the exit end 8a and the eye is the shortest, the scattering angle is set so that the irradiation density of the light incident on the eye is MPE or less.

As the light diffusion mechanism 9, for example, a resin containing a scatterer such as titanium oxide can be used. In addition, when a light diffusion plate such as a lens diffusion plate (LSD) is used, the scattering angle can be controlled with higher accuracy. In general, when the above scattering device is used, the scattering distribution is often Gaussian, and has a high light density in front of the exit end 8a and a low light density distribution in the side direction of the exit end 8a.

  A lens optical system can also be used as the light diffusion mechanism 9. FIG. 4 shows an optical path when a lens system is used for the light diffusion mechanism 9. When a lens optical system is used, it is possible to diffuse light isotropically by selecting an appropriate optical element. Thereby, a light irradiation density can be reduced efficiently.

  When the bundle fiber 3 is used for light transmission from the light source 4 to the emission end 8a, the energy density of the light emitted from the fiber tip 3a may be locally increased. This density distribution is reduced by the light passing through the light diffusion mechanism 9. Furthermore, when the combination of the lens optical system and the lens diffusion plate is used as the light diffusion mechanism 9, the local light distribution can be further reduced.

  In addition to the above configuration, it is more preferable to provide a shielding mechanism 12 at the probe tip as shown in FIG. This is a mechanism for physically preventing the eyes of an engineer or a subject from approaching the ejection end 8a. Thereby, even if various safety mechanisms are also removed, the amount of light entering the eyes can be reduced. The shielding mechanism 12 of FIG. 5 is preferably configured to retract to the same height as the injection port when pressed against the subject. Furthermore, if a locking mechanism (not shown) is provided and the shielding mechanism 12 is operated only when the probe is brought into contact with the subject or the locking mechanism is released by an operator's operation or the like, the safety is further improved.

  From the viewpoint of safety, not only the light irradiation density by the light scattering described above but also a combination with other light irradiation control methods is effective. For example, a mechanism for detecting contact with a subject, shutter control of laser light by a light irradiation switch, and the like are effective.

[Example 1]
In the photoacoustic apparatus described above, in this example, a photoacoustic image was acquired by the photoacoustic apparatus described in FIG. As the light source 4, an Nd: YAG laser and a Ti: sa laser using the same as excitation light were used. A bundle fiber 3 was used for light propagation, and a diffusion plate was provided at the fiber tip 3a as shown in FIG. In the photoacoustic probe 1, the probe 2 and the emitting portion 8 are integrally housed.

  For the light diffusion mechanism 9, a lens diffusion plate manufactured by Shibuya Optical Co., Ltd. was used as a diffusion plate (LSD) having a diffusion angle of 60 degrees. The fiber tip 3a and the diffusion plate 9 were 1 cm × 1 cm in size. In addition, the diffusion angle said here does not mean that it never diffuses at an angle beyond that. Moreover, it does not guarantee the uniformity of the light irradiation density within the diffusion angle. In a specific configuration, the range in which light is diffused and the light density distribution therein are individually determined according to the shape and intensity of light at the time of emission, the type and performance of the diffusion plate, the light passing distance, and the like.

  FIG. 6 shows how light is scattered at a position 3 cm away from the exit end 8a. The horizontal axis represents the diffusion angle, and the vertical axis represents the device specific value of the light intensity. When a diffusion plate is not provided for the solid line, the broken line is scattered by 10 degrees, and the alternate long and short dash line is scattered by 60 degrees. As shown in the figure, the light density in front of the probe can be greatly reduced by giving a scattering angle of 60 degrees. Therefore, a diffusion plate having a diffusion angle of 60 degrees or more is suitable. Since the light emitted from the fiber tip 3a in this embodiment has an emission angle of about 10 degrees, the light intensity is attenuated by a fraction due to the effect of installing the diffusion plate.

In this handheld type embodiment, an engineer operates the probe. There are various positions and operation methods of the subject and the technician at that time, but as an example, when the probe held by the technician is pressed against the breast of the subject in the supine or sitting position To consider. In this case, the bend angle between the upper arm and the forearm of the engineer is greater than 90 degrees, and the neck is assumed to be in an upright state or slightly bent forward. The distance between the probe tip and the technician's eyes in this state is estimated. The average length of the upper arm of an adult is 160 to 170 mm, and 140 mm when it is short. Accordingly, when the probe is unintentionally removed from the subject's skin during the procedure operation, the distance between the probe tip and the technician's eyes is assumed to be greater than 140 mm.

Here, in light with a wavelength of 756 nm, the MPE of a living body is 25.9 [mJ / cm ² ], and the MPE of the eye is 1.29 [mW / cm ² ]. Assuming that the laser is 10 Hz, the MPE ratio between the skin and the eyes is approximately 0.005 from 1.29 / 10 / 25.9. That is, the MPE of the eye corresponds to about 0.5% of the MPE of the skin. Therefore, when the irradiation density at the emission end 8a, which is the light irradiation position, is equal to the MPE value of the skin, it is safe if the irradiation density when the light enters the eye is 0.5% or less compared to the time of emission. Can be secured.

  FIG. 7 shows the relationship between the distance from the probe surface (horizontal axis, unit is cm) and the attenuation of light density (vertical axis, ratio with emission). From the figure, it is clear that the light quantity ratio at the time of emission at a position 14 cm away is smaller than 0.005. Therefore, even if the light quantity at the time of emission is equal to the MPE value with respect to the skin, it can be seen that the value is equal to or less than the MPE for the eye while the light reaches the eye from the probe.

  According to the present embodiment, even when light is unintentionally emitted from the probe into the air, the light is scattered at a wide angle over a short distance, and the energy density is lowered. As a result, the safety of the device is improved. On the other hand, when the probe is in contact with the subject, the energy density necessary for obtaining the characteristic information is ensured.

In this embodiment, LSD is used for light diffusion, but other light diffusion devices such as a resin kneaded with titanium oxide may be used.
In this embodiment, the MPE ratio of the skin and eyes when a pulse laser with a wavelength of 756 nm is used is assumed, but the same effect can be obtained by using an appropriate light diffusion plate even under other conditions.

[Example 2]
In the second embodiment, a lens system is used for the light diffusion mechanism. The schematic configuration of the photoacoustic apparatus is as shown in FIG. 1, and a concave lens 9 is installed at the fiber end 3a as shown in FIG. Due to the action of the concave lens 9, the light emitted from the bundle fiber 3 is diffused isotropically.

  FIG. 8 shows a light density distribution when the light in this embodiment propagates in space. In the figure, the horizontal axis indicates the distance (cm) from the probe surface, and the vertical axis indicates the attenuation of light density (ratio with respect to the time of emission). From the figure, it can be seen that the distance at which the amount of light irradiated to the skin is 0.005 times (0.5%) is about 5 cm away. In other words, considering the MPE ratio (0.005) of the skin and eyes, it can be seen that when the skin is irradiated with the MPE light amount, the safety of the eyes is maintained if the distance between the probe and the eyes is 5 cm or more.

  FIG. 9 shows the relationship between the light scattering angle (horizontal axis) at a distance of 140 mm from the probe and the light attenuation (ratio between vertical axis and emission). According to this result, by setting the scattering angle to 30 degrees or more, the light amount entering the eye is less than or equal to MPE even if light is unintentionally emitted into the air under the probe procedure conditions described in the first embodiment. Can be suppressed.

In the second embodiment, the light is scattered by the concave lens. In this case, the unevenness of the emitted light from the bundle fiber 3 is reflected in the emitted light. Therefore, the uniformity of the light distribution can be improved by disposing a diffuser plate at the tip of the concave lens.

[Example 3]
In the present embodiment, a method for further improving the safety will be described in addition to the methods of the above embodiments. That is, a method for preventing the emission of light with the eyes approaching the probe emission end 8a and the other safety mechanism removed.

  In the probe shown in FIG. 5, a shielding mechanism 12 is disposed at the tip of the emitting portion 8. The shielding mechanism 12 protrudes from the probe 2 and the light diffusion mechanism 9 to the front surface (subject side). Therefore, when the probe is brought close to the measurement object (for example, skin), the shielding mechanism 12 strikes the measurement object before the light diffusion mechanism 9. Therefore, even if the eye and the probe approach, the distance from the emission end 8a to the eye is ensured. As a result, safety is improved. The length of the shielding mechanism 12 is preferably a value such that the emitted light is equal to or less than the MPE for the eyes. For example, in the case of the light diffusion mechanism described in the second embodiment, the length of the shielding mechanism 12 may be 50 mm.

The shielding mechanism 12 is provided with a movable mechanism (not shown), and when the probe is pressed against the subject, it is preferably retracted to the same height as the emission end 8a. As a result, the amount of light applied to the skin can be secured, so that both safety and image quality can be improved.
Further, a locking mechanism (not shown) may be provided so that the shielding mechanism 11 is movable only when the probe is brought into contact with the subject or the locking mechanism is released by an operator's operation or the like.

[Example 4]
In this embodiment, in addition to scattering by the light diffusion mechanism 9, safety is improved by controlling light irradiation. In this embodiment, as shown in FIG. 10, the contact sensor 13 is arranged on the contact surface of the probe 1 with the subject. The photoacoustic apparatus controls opening / closing of a shutter (not shown) disposed on the front surface of the light source 4 by interlocking the contact sensor 13 with on / off. That is, only when the contact between the probe and any object is detected, the shutter is opened to allow light irradiation. On the other hand, when there is no object in contact with the probe, in other words, when the exit end 8a faces the air, the shutter is closed and light irradiation becomes impossible.

  According to the configuration of the present embodiment, not only the light after emission is diffused but also the light irradiation itself is controlled, so that the safety is further improved. The main point of the present embodiment is that the light emission is stopped unless the contact state is detected, and therefore the light control mechanism is not limited to the shutter. For example, the light control mechanism may control the presence or absence of light emission by Q switch control or power supply control of the laser device.

[Example 5]
In this embodiment, the principle of the present invention is applied to a probe having a bowl-type probe 20 instead of a hand-held probe. FIG. 11 shows a cross-sectional configuration in the vicinity of the probe in this embodiment. The configuration of the light source portion, the operation of the processing apparatus, and the like are the same as those in the above embodiments.

  The probe 20 of this embodiment is of a type called bowl type or hemispherical type. Inside the bowl-shaped surface, the receiving element is arranged so as to form a high sensitivity region near the center of the hemisphere. A member 30 that covers the tip of the bundle fiber 3 is disposed at the center of the probe 20. The light emitted from the bundle fiber 3 reaches the subject 10 via the acoustic matching material 14 (for example, water). Although a bowl shape is mentioned here as a typical example of the probe shape, it has a plurality of receiving elements, and at least some of the elements have high receiving sensitivity directions (directing axes) intersect to form a high sensitivity region. This embodiment can be applied to any probe that does.

  In this embodiment, a light diffusion mechanism 9 is disposed between the acoustic matching material 14 and the subject 10. Thereby, the emitted light from the bundle fiber 3 is diffused. As a material of the light diffusion mechanism, a material that transmits light while diffusing, and a material that transmits a photoacoustic wave generated from the subject to the probe are preferable. For example, a material in which titanium oxide is kneaded into a resin can be used as the light diffusion mechanism. Preferably, the light diffusion mechanism also serves to hold the subject 10.

  In addition, a holding member for an object may be provided separately from the light diffusing mechanism, and the light diffusing mechanism may be installed on the holding member by application, pasting, combination or the like. The holding member is preferably made of a material that transmits light and acoustic waves. If the subject is a breast, a cup-shaped holding member is preferable, and the cup may be exchanged according to the size of the subject.

  The light emitted from the bundle fiber 3 spreads at an emission angle of 16.7 degrees and irradiates the subject. At this time, it is not preferable that the laser beam is accidentally emitted without the subject 10. Specifically, when there is no light diffusion mechanism, the light irradiation density is attenuated to MPE or less for the eyes at a distance of 73 cm from the bottom surface of the light diffusion mechanism. Therefore, when an engineer or a subject looks into the ejection end from a distance of 73 cm or less from the bottom surface, there is a risk of eye safety problems.

  Therefore, in this embodiment, the light diffusing mechanism 9 is provided to further scatter the light emitted from the bundle fiber by 70 degrees. As a result, the distance at which the light irradiation density was equal to or less than the MPE of the eyes was about 10 cm from the bottom surface of the light diffusion mechanism 9, and safety was improved.

  As described above, according to the present invention, the irradiated light is scattered from the irradiation port to a wide angle after being emitted, so that the energy density can be reduced at a short distance even when unintended energy is emitted. On the other hand, when the subject and the probe are in contact, the energy density necessary for obtaining a desired image can be ensured. As a result, safety can be improved while obtaining a good subject image by the photoacoustic apparatus.

  DESCRIPTION OF SYMBOLS 1: Photoacoustic probe, 2: Probe, 3: Bundle fiber, 4: Light source, 5: Optical system, 6: Processing apparatus, 8: Injecting part, 9: Light diffusion mechanism

Claims (13)

A light source that generates light;
An optical system that propagates the light;
An emission part for emitting the light propagated through the optical system;
A receiving unit that receives an acoustic wave generated from the subject irradiated with the light and outputs an electrical signal; and
A processing unit for acquiring information inside the subject using the electrical signal;
Have
The emission part has a diffusion mechanism that reduces the irradiation density at a position 14 cm away from the light irradiation position in air to 0.5% or less of the irradiation density at the light irradiation position of the emission part. A subject information acquisition apparatus. The object information acquiring apparatus according to claim 1, wherein the diffusion mechanism is a diffusion plate. The object information acquiring apparatus according to claim 2, wherein a diffusion angle of the diffusion plate is 60 degrees or more. The object information acquiring apparatus according to claim 1, wherein the diffusion mechanism is a concave lens. The object information acquiring apparatus according to claim 1, wherein the light is a pulse laser having a wavelength of 700 nm to 900 nm. The object information acquiring apparatus according to claim 1, wherein the optical system includes a bundle fiber. The object information acquiring apparatus according to claim 1, further comprising a shielding mechanism protruding from an emission end of the emission unit. A contact sensor that detects whether or not the injection end of the emission unit and the subject are in contact with each other;
A light control mechanism that stops emission of the light when the contact sensor detects that it is not in a contact state;
The object information acquiring apparatus according to claim 1, further comprising: An emission unit for emitting light to irradiate the subject;
A receiver that receives an acoustic wave generated from the subject irradiated with the light;
Have
The emission part has a diffusion mechanism that reduces the irradiation density at a position 14 cm away from the light irradiation position in air to 0.5% or less of the irradiation density at the light irradiation position of the emission part. A handheld probe. The handheld probe according to claim 9, wherein the diffusion mechanism is a diffusion plate. The handheld probe according to claim 10, wherein a diffusion angle of the diffusion plate is 60 degrees or more. The handheld probe according to claim 9, wherein the diffusion mechanism is a concave lens. The object information acquiring apparatus according to claim 9, wherein the emission unit includes a member that covers at least a tip of the bundle fiber.

Images