JP2014168631A - Subject information acquisition device, and control method of subject information acquisition device - Google Patents

Abstract

An object information acquisition apparatus capable of accurately acquiring a photoacoustic signal generated in an object is provided.
A subject support member having an opening for inserting a subject which is a part of the subject, a light irradiation unit for irradiating light to the subject inserted in the opening, and the subject A holding member that holds the subject, and a scanning mechanism that moves the light irradiation unit along a first axis parallel to the insertion direction of the subject; A probe for receiving an acoustic wave generated due to light irradiated on the subject, a processing unit for generating characteristic information of the subject from the acoustic wave received by the probe, and the holding The position of the light irradiation unit with respect to the member is determined based on the position of the holding member and the emission direction of the light emitted from the light irradiation unit, and the light irradiation unit is moved to the determined position using the scanning mechanism. And a control unit to be moved.
[Selection] Figure 1

Description

  The present invention relates to a subject information acquisition apparatus and a control method thereof, and particularly relates to a technique for improving the intensity of a signal generated in a subject.

Many proposals have been made so far regarding techniques for non-invasive imaging of tomographic images inside a subject. One of them is Photoacoustic Tomography (PAT: Photoacoustic Tomography) that acquires biological function information using light and ultrasonic waves.
Photoacoustic tomography is an acoustic wave (typically ultrasound) generated by irradiating a subject with pulsed light (hereinafter referred to as measurement light) generated by a light source and absorbing the light within the subject. It is a technology that receives and analyzes and visualizes the internal tissue of the subject. By analyzing the received acoustic wave, an initial sound pressure distribution caused by the light absorber in the subject can be obtained. Further, by calculating the initial sound pressure distribution in consideration of the light distribution, information related to optical characteristics such as the absorption coefficient inside the subject can be obtained.

  The sound pressure of the acoustic wave generated in the subject in PAT is proportional to the local light quantity that reaches the light absorber. Therefore, in order to obtain information inside the living body with high accuracy, it is necessary to increase the amount of measurement light emitted to the subject.

As an apparatus for diagnosing breast cancer using the PAT technique, there is an apparatus described in Non-Patent Document 1, for example. In this apparatus, the amount of measurement light reaching the inside of the breast is secured by pressing and holding the breast with two holding members.
On the other hand, diagnosis of breast cancer cannot be performed accurately unless the region including not only the breast but also the base chest wall portion is observed. That is, when diagnosing breast cancer using a PAT device, it is necessary to increase the amount of measurement light emitted not only to the breast but also to the vicinity of the chest wall in order to accurately obtain information about the chest wall.
There exists a photoacoustic imaging device of patent document 1 in invention which solves this subject. In this apparatus, the light irradiation unit is arranged so that the light irradiated on the subject is directed toward the chest wall, thereby increasing the amount of measurement light irradiated on the chest wall.

JP 2011-183057 A

Susanne E. et al., “First clinical trials of the Twente photoacoustic mammoscope (PAM)”, Proceedings of the SPIE, Vol.6629, pp.662917, 2007

  However, in the apparatus described in Patent Document 1, measurement light must be emitted from the entire surface of the holding member that is in contact with the breast, and thus an enormous number of light irradiation units are required, resulting in an unrealistic apparatus configuration. . In order to achieve a realistic apparatus configuration, it is necessary to provide a small light irradiation unit for the subject, and to move the light irradiation unit while irradiating the held breast with measurement light. However, in such a measurement apparatus that scans the light irradiation unit, measurement light is incident on the subject perpendicularly, and therefore, a sufficient amount of light cannot be irradiated near the chest wall. That is, there is a problem that a photoacoustic signal generated near the chest wall cannot be obtained with high accuracy.

In order to solve this problem, as shown in FIG. 9A, a method is conceivable in which scanning is performed with the measurement light emission direction tilted toward the chest wall.
However, this method also has problems. Since the position of the movable holding member varies depending on the thickness when the breast is pressed, the distance between the light irradiation unit and the movable holding member is not constant. That is, when the measurement light is incident on the subject at an angle other than perpendicular, the position to which the measurement light is irradiated changes depending on the position of the movable holding member as shown in FIG. There may occur a case in which measurement light cannot be irradiated to a region (for example, a region indicated by a circle).

  The present invention has been made in view of such problems, and an object of the present invention is to provide a subject information acquisition apparatus that can accurately acquire a photoacoustic signal generated in a subject.

In order to solve the above problems, a subject information acquisition apparatus according to the present invention includes:
A subject support member having an opening for inserting a subject which is a part of the subject, a light irradiation unit for irradiating light to the subject inserted into the opening, the subject and the light irradiation A holding member that holds the subject, a scanning mechanism that moves the light irradiation unit along a first axis parallel to the insertion direction of the subject, and the subject A probe for receiving an acoustic wave generated due to light irradiated on the probe, a processing unit for generating characteristic information of the subject from the acoustic wave received by the probe, and the light for the holding member A control unit that determines the position of the irradiation unit based on the position of the holding member and the emission direction of the light emitted from the light irradiation unit, and moves the light irradiation unit to the determined position using the scanning mechanism. It is characterized by having.

In addition, the control method of the subject information acquisition apparatus according to the present invention includes:
A subject support member having an opening for inserting a subject which is a part of the subject, a light irradiation unit for irradiating light to the subject inserted into the opening, the subject and the light irradiation An object information acquisition apparatus having a holding member that holds the object and a probe that receives an acoustic wave generated due to light irradiated on the object A control method for determining a position of the light irradiation unit with respect to the holding member based on a position of the holding member and an emission direction of light emitted from the light irradiation unit, and the light irradiation unit. Moving to the determined position along a first axis parallel to the insertion direction of the subject and irradiating light, and receiving the acoustic wave by the probe; Generate characteristic information of the subject from the received acoustic wave Characterized in that it comprises a processing step.

  ADVANTAGE OF THE INVENTION According to this invention, the subject information acquisition apparatus which can acquire the photoacoustic signal which generate | occur | produces in a subject accurately can be provided.

The block diagram of the photoacoustic measuring device which concerns on 1st embodiment. The figure explaining the light irradiation part which concerns on 1st embodiment. The flow chart of the measurement in a first embodiment. The figure explaining another structural example of the light irradiation part which concerns on 1st embodiment. The block diagram of the photoacoustic measuring device which concerns on 2nd embodiment. The measurement flow figure in 2nd embodiment. FIG. 6 is a diagram for explaining the effect of the first embodiment. FIG. 10 is a diagram for explaining the effect of the second embodiment. The figure for demonstrating the subject of invention.

(First embodiment)
Hereinafter, a first embodiment of the present invention will be described in detail with reference to the drawings.
The photoacoustic measurement apparatus according to the first embodiment irradiates a subject with measurement light, and receives and analyzes an acoustic wave generated in the subject due to the measurement light, so that the inside of the living body that is the subject This is an apparatus for imaging the information.

<System configuration>
First, the configuration of the photoacoustic measurement apparatus according to the present embodiment will be described with reference to FIG.
The photoacoustic measurement apparatus according to the first embodiment includes chest wall support parts 102a and 102b, a holding member 103, a light source 104, a light transmission part 105, a light irradiation part 106, a scanning mechanism 107, a rotation mechanism 108, a control part 109, a probe. It comprises a touch element 113, a processing unit 115, and a potentiometer 116. The holding member 103 includes a movable holding member 103a and a fixed holding member 103b.
Although not constituting the apparatus, in FIG. 1, reference numerals 101a and 101b are a subject, reference numeral 110 is measurement light, reference numerals 111a and 111b are light absorbers, reference numerals 112a and 112b are acoustic waves, and reference numeral 114 is an acoustic wave. Represents a matching agent. In the description of the embodiment, a and b in the reference numerals are omitted when there is no need to distinguish between them.

In the measurement, a breast as a subject is inserted into an opening opened in the chest wall support portion 102 (subject support member in the present invention), and the inserted breast is sandwiched between the movable holding member 103a and the fixed holding member 103b. Do.
First, the subject 101 is irradiated with pulsed light emitted from the light irradiation unit 106 through the movable holding member 103a. When a part of the energy of light propagating through the subject is absorbed by a light absorber such as blood, an acoustic wave is generated due to thermal expansion of the light absorber. The acoustic wave generated in the subject is received by the probe 113 through the fixed holding member 103b and analyzed by the processing unit 115. Since the analysis result is output as an image representing the characteristic information in the subject, the photoacoustic measurement device according to the present embodiment can also be called a subject information acquisition device.
Hereinafter, each means which comprises the photoacoustic measuring device which concerns on this embodiment is demonstrated.

<< light source 104 >>
The light source 104 is a device that generates pulsed light. The light source is preferably a laser light source in order to obtain a large output, but a light emitting diode, a flash lamp, or the like can be used instead of the laser. When a laser is used as the light source, various lasers such as a solid laser, a gas laser, a dye laser, and a semiconductor laser can be used. The timing, waveform, intensity, etc. of irradiation are controlled by a light source control unit (not shown). The light source control unit may be integrated with the light source.
In order to effectively generate photoacoustic waves, light must be irradiated in a sufficiently short time according to the thermal characteristics of the subject. When the subject is a living body, the pulse width of the pulsed light generated from the light source is preferably about 10 to 50 nanoseconds. Further, the wavelength of the pulsed light is preferably a wavelength at which the light propagates to the inside of the subject. Specifically, when the subject is a living body, the thickness is preferably 600 nm or more and 1100 nm or less.

<< Optical transmission unit 105 >>
The light transmission unit 105 is means for guiding the pulsed light generated by the light source 104 to the subject 101. Specifically, the optical member is composed of an optical fiber, a lens, a mirror, a diffusion plate, or the like so as to obtain a desired beam shape and light intensity distribution. Using these optical members, the irradiation conditions such as the irradiation shape of the pulsed light, the light density, and the irradiation direction of the subject can be set arbitrarily.

<< Light irradiation unit 106 >>
The light irradiation unit 106 is means for emitting measurement light to the subject. The light irradiation unit 106 may be integrated with the light source, or may be connected to the light source via an optical member such as a lens, a mirror, a diffusion plate, or an optical fiber. In the present embodiment, the light source 104, the light transmission unit 105, and the light irradiation unit 106 are connected to each other.
Moreover, the light irradiation part 106 is installed in the state which inclined in the diagonal direction so that the emission direction of measurement light may face the subject's chest wall side. The tilt angle can be set to 10 degrees, for example.

<< Scanning mechanism 107 >>
The scanning mechanism 107 is a means for moving the light irradiation unit 106 along the subject 101. The scanning mechanism 107 can move the light irradiation unit 106 in the vertical direction in FIG. 1, that is, in the direction perpendicular to the paper surface in addition to the insertion direction of the subject. That is, the light irradiation unit 106 can be moved in a two-dimensional direction by the scanning mechanism 107. The position of the light irradiation unit 106 on the scanning mechanism 107 is controlled by the control unit 109 described below. By combining the scanning mechanism 107 and the control unit 109, photoacoustic measurement can be performed while the light irradiation unit is scanned two-dimensionally. Note that the vertical direction in FIG. 1 is the first axis in the present invention. In the description of the embodiment, it is also referred to as a first axis.

<< Control unit 109 >>
The control unit 109 is means for controlling the position of the light irradiation unit 106 by driving the scanning mechanism 107. Specifically, the position of the light irradiation unit 106 is determined in the vertical direction in FIG.
When holding the breast between two holding members, the position of the holding member varies depending on the size of the breast. Since the measurement light is directed to the chest wall side, when the distance between the two holding members is wide, the light is irradiated to a place far from the chest wall, but when the distance between the two holding members is narrow, Light is applied to a place close to the chest wall.
For the above reasons, when it is desired to irradiate a desired range on the movable holding member 103a with the measurement light, the movement range of the light irradiation unit 106 on the first axis (hereinafter referred to as the scanning range) according to the position of the movable holding member 103a Need to be determined as appropriate. The control unit 109 acquires the distance between the light irradiation unit 106 and the holding member 103a, and determines the scanning range according to the distance and the emission direction of the measurement light. A specific method for determining the scanning range will be described later.

<< Subject 101 (Light Absorber 111) >>
The subject 101 and the light absorber 111 do not constitute the present invention, but will be described here. The subject 101 is an object for performing photoacoustic measurement, and is typically a living body. Here, a human breast is used as a subject.
In the photoacoustic measurement apparatus according to the present embodiment, the light absorber 111 having a large light absorption coefficient existing inside the subject 101 can be imaged. When the subject is a living body, the light absorber 111 is specifically water, lipid, melanin, collagen, protein, oxygenated hemoglobin, reduced hemoglobin, or the like. By imaging the light absorber, the photoacoustic measurement apparatus according to the present embodiment can perform blood vessel contrast, diagnosis of human or animal malignant tumors or vascular diseases, follow-up of chemical treatment, and the like.

<< Holding member 103 >>
The holding member 103 is means for holding the subject 101, and in the present embodiment, includes two holding members 103a and 103b (hereinafter referred to as a movable holding member 103a and a fixed holding member 103b, respectively). Of the two holding members, one of the side with the probe (fixed holding member 103b) is fixed to the breast, but one side with the light irradiation part (movable holding member 103a) The light irradiation unit 106 can be moved independently of the breast so as to compress the breast.
In order to acoustically couple the probe and the subject, the holding member 103 is preferably made of a material having an acoustic impedance close to that of the subject. However, when the object is sandwiched and held by two holding members and light is irradiated to the surface of the object opposite to the probe as in this embodiment, the movable holding member 103a on the light irradiation side is irradiated. The acoustic impedance does not need to be considered, and any material having a high transmittance with respect to the measurement light may be used. Typically, a plastic plate such as acrylic, a glass plate, polymethylpentene, or the like can be given.

<< Probe 113 >>
The probe 113 is means for converting an acoustic wave (typically an ultrasonic wave) generated inside the subject 101 into an analog electric signal. The probe 113 may be composed of a single acoustic detector or a plurality of acoustic detectors. Further, the probe 113 may be one in which a plurality of receiving elements are arranged one-dimensionally or two-dimensionally. When a multidimensional array element is used, acoustic waves can be received at a plurality of locations at the same time, so that the measurement time can be shortened. If the probe is smaller than the subject, the probe may be scanned to receive acoustic waves at a plurality of positions. Further, the light irradiation unit 106 and the probe 113 may be disposed so as to sandwich the subject as in the present embodiment, or may be disposed on the same side.

Further, it is desirable that the probe 113 has high sensitivity and a wide frequency band. Specific examples include PZT (piezoelectric ceramics), PVDF (polyvinylidene fluoride resin), cMUT (capacitive micromachined ultrasonic transducer), and those using a Fabry-Perot interferometer. However, the present invention is not limited to those listed here, and any one may be used as long as it satisfies the function as a probe.
Further, the probe 113 needs to be acoustically coupled to the subject 101 (and the fixed holding member 103b) in order to eliminate the influence of acoustic wave reflection and attenuation. For example, it is desirable to provide an acoustic matching material or an acoustic matching material such as water or oil between the probe 113 and the fixed holding member 103b. In the present embodiment, the acoustic matching material 114 is disposed between the probe 113 and the fixed holding member 103b.

<< Processor 115 >>
The processing unit 115 is means for amplifying the electrical signal obtained by the probe 113 and converting it into a digital signal, and processing the digital signal to generate an image. The processing unit 115 generates an image representing the distribution of the initial sound pressure due to the light absorber in the subject and an image representing the distribution of the absorption coefficient. The processing unit 115 may be a computer having a CPU, a main storage device, and an auxiliary storage device, or may be hardware designed exclusively.

<< Potentiometer 116 >>
The potentiometer 116 is a means for measuring the thickness of the subject in a state where the subject 101 is held (hereinafter referred to as holding thickness). The potentiometer 116 can acquire the distance between the movable holding member 103a and the light irradiation unit 106 in a state where the subject is held.

<Overview of measurement process>
Next, an outline of measurement processing performed by the photoacoustic measurement apparatus according to the first embodiment will be described with reference to FIGS. 1 (a), 1 (b), and 2. FIG. FIG. 1A is a diagram showing a case where the holding thickness of the subject is thin, and FIG. 1B is a diagram showing a case where the holding thickness of the subject is thick. FIG. 2 is an enlarged view of the periphery of the light irradiation unit 106.

The holding thickness of the object is measured by a potentiometer 116. The measured information is transferred to the control unit 109, and the control unit 109 determines the scanning range of the light irradiation unit 106, that is, the movement range on the first axis, according to the position of the movable holding member 103a.
A method for determining the scanning range will be described more specifically. Here, the reference holding thickness (for example, the minimum holding thickness in the apparatus) and the scanning range of the light irradiation unit 106 for irradiating the predetermined range of the holding member 103a with the measurement light are determined in advance. It shall be. Assuming that the emission angle of the measuring light 110 with respect to the movable holding member 103a is θ, every time the movable holding member 103a approaches the light irradiation unit 106 by ΔL, the upper end of the scanning range of the light irradiation unit 106 (the end near the chest wall). Is moved to the chest wall side by ΔL · tan θ.

  For example, when the angle θ of the light irradiation unit 106 with respect to the movable direction of the movable holding member 103a is 10 degrees as shown in FIG. 2, the upper end of the scanning range of the light irradiation unit 106 is increased every time the holding thickness becomes 1 mm. 1 mm × tan 10 ° ≈0.176 mm is controlled to approach the chest wall side. When this control is not performed, an area where the measurement light is not irradiated is generated on the movable holding member 103a due to an increase in the holding thickness. In the present embodiment, this can be prevented. The scanning range is defined by the upper end and the lower end. The upper end of the scanning range determined here is the first point in the present invention, and the lower end of the scanning range is the second point in the present invention.

  The measurement light 110 irradiated to the subject 101 propagates while diffusing in the subject 101, and a part thereof is absorbed by a light absorber such as a blood vessel (in the example of FIG. 1, the light absorber 111). . The light absorber that has absorbed the light generates an acoustic wave (acoustic wave 112 in the example of FIG. 1) by the photoacoustic effect. The generated acoustic wave propagates through the subject 101, and a part of the acoustic wave reaches the probe 113 through the fixed holding member 103b. The acoustic wave received by the probe 113 is transferred to the processing unit 115 as an electric signal and processed into desired data such as an image representing a light absorption coefficient.

<Measurement processing flowchart>
Next, a flow for performing the processing described above will be described with reference to FIG.
First, a user of the apparatus inserts a subject into the apparatus (S101). The chest of the subject is supported by the chest wall support 102. Next, the inserted subject, that is, the breast is pressed by the holding means 103. Specifically, the movable holding member 103a moves and compresses the breast in a form of pressing against the fixed holding member 103b.
When the process of step S102 is completed, the potentiometer 116 acquires the retention thickness of the breast (S103), and notifies the control unit 109 of the result (S104).
When acquisition of the holding thickness is completed, the control unit 109 determines the scanning range of the light irradiation unit 106 (S105). And the control part 109 irradiates measurement light using the determined scanning range, and the process part 115 acquires a signal (S106).

  According to the first embodiment, the control unit automatically corrects the scanning range of the light irradiation unit by detecting the holding thickness of the subject. Thereby, it becomes possible to always irradiate the measurement light to the same range on the subject regardless of the holding thickness of the subject.

  In the first embodiment, the holding thickness is acquired using the potentiometer 116, but other methods may be used. For example, the holding thickness of the subject may be manually measured, and the measured value may be input to the control unit. Further, in the present embodiment, an example in which the light irradiation unit 106 is fixed in a tilted state has been described, but the measurement light may be tilted using another method. FIG. 4 shows another configuration example of the light irradiation unit 106. In FIG. 4, reference numerals 117a and 117b denote light reflecting members. With the configuration as shown in FIG. 4, only the emitted measurement light can be tilted toward the subject's chest wall.

(Second embodiment)
In the first embodiment, measurement was performed while pressing the subject using two holding members. On the other hand, the second embodiment is an embodiment that performs measurement by holding a subject using a hemispherical holding member.

  FIG. 5 is a diagram for explaining the second embodiment. FIG. 5A shows a case where the breast is small, and FIG. 5B shows a case where the breast is large. In this embodiment, rather than compression by a movable member, a hemispherical holding member suitable for the size of the breast is attached to the apparatus, and the breast is inserted and held. That is, when the breast is large, a large holding member is used, and when the breast is small, a small holding member is used. In principle, the same components as those in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted.

The holding members 203a and 203b are hemispherical holding members. The advantage of making the holding member hemispherical is that the burden on the subject can be reduced because the breast is not compressed. In order to eliminate a gap between the breast and the holding member, it is desirable to use a holding member having a size corresponding to the size of the subject's breast.
In the second embodiment, the input unit 216 is used instead of the potentiometer 116. The input unit 216 is a means for inputting the size of the holding member to be used. With this, the control unit 109 can acquire the distance between the light irradiation unit 106 and the holding member 203.
When a hemispherical holding member is used, since the size of the holding member 203 changes according to the size of the breast, the position where the measurement light is irradiated changes. Specifically, when the holding member 203 is small, the light is irradiated near the chest wall, whereas when the holding member 103 is large, the light is irradiated to a place far from the chest wall. Therefore, in the second embodiment, the scanning range of the light irradiation unit 106 is determined according to the size of the holding member.

  Also in the second embodiment, as in the first embodiment, the size of the holding member serving as a reference (for example, a holding member having the smallest usable size) and the light irradiation unit 106 when the holding member is used. The scanning range is determined in advance. Then, every time the radius of the holding member becomes 1 mm larger than the reference size, the control unit 109 performs control to bring the upper end of the scanning range of the light irradiation unit 106 closer to the chest wall side by 1 mm × tan 10 ° ≈0.176 mm. .

FIG. 6 is a processing flow of the photoacoustic measurement apparatus according to the second embodiment.
In the second embodiment, before step S101 for inserting a subject, step S101A for attaching a holding member having a size suitable for the subject to the apparatus is added. Further, steps S102 and S103 are omitted, and instead, step S104A for inputting the size of the attached holding member is executed. In step S105, the method by which the control unit 109 determines the scanning range of the light irradiation unit 106 is as described above.

  Thus, in the second embodiment, even when a hemispherical holding member is used, the amount of light irradiated to the chest wall can be increased, as in the first embodiment, and as a result, In addition, information near the chest wall can be obtained with high accuracy. In particular, according to the second embodiment, since the pressure on the breast is not held, the physical burden on the subject can be reduced.

In the second embodiment, the user of the apparatus inputs the size of the holding member, but other methods may be used. For example, the scanning range of the light irradiation unit 106 may be determined by measuring the size of the holding member using a potentiometer and transferring the measured value to the control unit 109.
Also in the second embodiment, as in FIG. 4, instead of tilting the light irradiation unit 106 itself, only measurement light may be directed toward the subject's chest wall using an internal mechanism.

Example 1
Next, Example 1 corresponding to the first embodiment will be described.
In Example 1, tungsten carbide having a thickness of 3 mm was used as the first chest wall support portion 102a and the second chest wall support portion 102b. The breast, which is the subject, is held between the movable holding plate 103a and the fixed holding plate 103b. A titanium / sapphire laser having a variable wavelength was used as the light source 104. The laser used has a pulse width of 10 nanoseconds, a frequency of 10 Hz, and a wavelength of 797 nm. The measurement light 110 emitted from the light irradiation unit 106 is substantially parallel light.

  In order to efficiently receive the acoustic wave from the subject, a movable holding member made of acrylic and having a thickness of 20 mm was used as the movable holding member 103a.

  As the fixed holding member 103b, a member made of polymethylpentene and having a thickness of 7 mm was used. The probe 113 was a piezoelectric probe made of PZT (titanium zinc zirconate). Further, in order to achieve acoustic matching between the fixed holding member 103 b and the probe 113, an acoustic matching agent 114 made of castor oil is disposed between the fixed holding member 103 b and the probe 113.

  The angle θ of the light irradiation unit 106 was set to 10 degrees, and control was performed so that the upper end of the scanning range of the light irradiation unit 106 was brought closer to the chest wall side by 1 mm × tan 10 ° ≈0.176 mm every time the holding thickness became 1 mm.

FIG. 7A shows the light irradiation density distribution irradiated to the subject when the holding thickness is 20 mm. The X axis in FIG. 7A is the direction perpendicular to the plane of FIG. 1A, and the origin is the center of the breast. Further, the Y axis in FIG. 7A is a direction perpendicular to the second chest wall support portion 102b, and the origin is the support surface of the second chest wall support portion.
FIG. 7B is a value obtained by integrating the light irradiation density at Y = −10 mm in the X direction. A dotted line in FIG. 7B indicates a case where the upper end of the scanning range of the light irradiation unit 106 is not corrected according to the holding thickness. On the other hand, the solid line in FIG. 7B shows a case where the upper end of the scanning range of the light irradiation unit 106 is corrected according to the holding thickness. As a result, it was confirmed that by correcting the upper end of the scanning range of the light irradiation unit 106 according to the holding thickness, it is possible to secure the amount of measurement light emitted near the chest wall regardless of the holding thickness.

(Example 2)
Next, Example 2 corresponding to the second embodiment will be described. In the second embodiment, only the holding member is different from the first embodiment, and other conditions are the same as those in the first embodiment.
In Example 2, a 1 mm thick hemispherical member made of polymethylpentene was used as the holding member 203. The opening of the holding member is circular. An appropriate size of the holding member can be selected according to the size of the breast of the subject. In addition, the center position of the holding member in the holding surface is constant regardless of the size of the holding member. The size of the selected holding member is directly input to the input unit 216 by the operator. The inputted size of the holding member is transferred to the control unit 109, and the scanning range of the light irradiation unit 106 is determined according to the size.
The angle θ of the light irradiation unit 106 is set to 10 degrees as in the first embodiment, and the upper end of the scanning range of the light irradiation unit 106 is 1 mm × tan 10 ° ≈0.176 mm every time the radius of the holding member increases by 1 mm. Control to bring it closer to the chest wall was performed.

FIG. 8A shows the light irradiation density distribution with which the subject is irradiated when the radius of the holding member is 10 mm. The X axis in FIG. 8A is the direction perpendicular to the plane of FIG. 5A and FIG. 5B, and the origin is the center of the breast. 8A is a direction perpendicular to the support surface of the chest wall support 102, and the origin is the support surface. FIG. 8B shows a value obtained by integrating the light irradiation density at Y = −10 mm in the X direction. A dotted line in FIG. 8B indicates a case where the upper end of the scanning range of the light irradiation unit 106 is not corrected according to the size of the holding member.
On the other hand, the solid line in FIG. 8B shows a case where the upper end of the scanning range of the light irradiation unit 106 is corrected according to the size of the holding member. As a result, it was confirmed that by correcting the upper end of the scanning range of the light irradiation unit 106, it is possible to secure the amount of measurement light irradiated near the chest wall regardless of the size of the holding member.

  DESCRIPTION OF SYMBOLS 104 ... Light source, 105 ... Light transmission part, 106 ... Light irradiation part, 107 ... Scanning mechanism, 109 ... Control part, 113 ... Probe, 115 ... Processing part

Claims (10)

A subject support member having an opening for inserting a subject which is a part of the subject; and
A light irradiation unit for irradiating light to the subject inserted into the opening;
A holding member that is disposed between the subject and the light irradiation unit and holds the subject;
A scanning mechanism for moving the light irradiation unit along a first axis parallel to the insertion direction of the subject;
A probe for receiving an acoustic wave generated due to light irradiated on the subject; and
A processing unit for generating characteristic information of the subject from an acoustic wave received by the probe;
The position of the light irradiation unit with respect to the holding member is determined based on the position of the holding member and the emission direction of light emitted from the light irradiation unit, and the light irradiation is performed using the scanning mechanism at the determined position. A control unit for moving the unit,
A subject information acquisition apparatus characterized by comprising: The control unit moves the light irradiation unit so that the light is irradiated to a predetermined range along the first axis of the holding member, and the movement range of the light irradiation unit is the light irradiation The object information acquiring apparatus according to claim 1, wherein the object information acquiring apparatus is determined based on a distance between a portion and the holding member and an emission direction of light emitted from the light irradiation unit. The moving range of the light irradiation unit is defined using a first point and a second point farther from the opening than the first point,
The subject information according to claim 2, wherein the control unit arranges the first point closer to the opening as the distance between the light irradiation unit and the holding member is shorter. Acquisition device. The said holding member contains two holding plates hold | maintained on both sides of a test object, At least 1 sheet | seat can move between the said test object and the said light irradiation part, It is characterized by the above-mentioned. 2. The object information acquiring apparatus according to 1. The said holding member is a hemispherical member that covers and holds the subject, at least a part of which is located between the subject and the light irradiation unit. Subject information acquisition apparatus. A subject support member having an opening for inserting a subject which is a part of the subject; and
A light irradiation unit for irradiating light to the subject inserted into the opening;
A holding member that is disposed between the subject and the light irradiation unit and holds the subject;
A probe for receiving an acoustic wave generated due to light irradiated on the subject; and
A method for controlling a subject information acquisition apparatus comprising:
A control step of determining the position of the light irradiation unit with respect to the holding member based on the position of the holding member and the emission direction of light emitted from the light irradiation unit;
A light irradiation step of moving the light irradiation unit to the determined position along a first axis parallel to the insertion direction of the subject and irradiating light; and
A receiving step of receiving an acoustic wave by the probe;
A processing step of generating characteristic information of the subject from the received acoustic wave;
A method for controlling a subject information acquiring apparatus. In the control step, the light irradiation unit is moved so that the light is irradiated to a predetermined range along the first axis of the holding member, and the movement range of the light irradiation unit is the light irradiation. The method for controlling a subject information acquiring apparatus according to claim 6, wherein the control method is determined based on a distance between the light source and the holding member and an emission direction of light emitted from the light irradiation unit. The moving range of the light irradiation unit is defined using a first point and a second point farther from the opening than the first point,
The subject information according to claim 7, wherein, in the control step, the first point is arranged closer to the opening as the distance between the light irradiation unit and the holding member is shorter. Control method of acquisition device. 9. The holding member includes two holding plates that hold a subject with at least one of them being movable between at least one of the subject and the light irradiation unit. 2. A method for controlling the subject information acquiring apparatus according to 1. 9. The holding member according to claim 8, wherein the holding member is a hemispherical member that covers and holds the subject, and at least a part of the holding member is located between the subject and the light irradiation unit. A method for controlling an object information acquiring apparatus.

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