JP2016027926A - Subject information acquisition device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a technology capable of suppressing the influence of an error due to a movement of a subject in a subject information acquisition device for acquiring a photoacoustic signal by using light of a plurality of wavelengths.SOLUTION: A subject information acquisition device is used. The subject information acquisition device includes a light source part for irradiating pulse light of a plurality of wavelengths, a wavelength control part for switching wavelengths of the pulse light, a probe for receiving acoustic waves generated in a subject irradiated by the pulse light to propagate, a scan control part for moving the probe within a prescribed scanning range, and an information processing part for acquiring subject information by using a plurality of electric signals corresponding to the pulse light of a plurality of wavelengths, outputted from the probe at each receiving position within the scanning range. The wavelength control part switches wavelengths of the pulse light before the probe scans the entire scanning range while receiving acoustic waves corresponding to the pulse light of at least one wavelength among the plurality of wavelengths at each receiving position.SELECTED DRAWING: Figure 5

Description

  The present invention relates to a subject information acquisition apparatus.

Conventionally, an X-ray mammography apparatus is known as an effective image diagnosis apparatus for finding and diagnosing breast cancer. In recent years, attention has been focused on a technique for transmitting light energy into a subject, receiving a photoacoustic signal generated as a result of thermal expansion due to absorption of light energy, and imaging the inside of the subject based on the photoacoustic signal. Yes. The photoacoustic signal is an acoustic wave such as an ultrasonic wave, and is also called a photoacoustic wave.
In order to receive and process a photoacoustic signal, it is desirable to receive the photoacoustic signal and convert it to an electrical signal. Therefore, it is common to convert a photoacoustic signal into an electrical signal by using a conversion element such as a CMUT (Capacitive Micromachined Ultrasonic Transducer) manufactured using a piezoelectric element or semiconductor technology. In practice, a probe in which a plurality of such conversion elements are arranged is often used.

  However, it is difficult in terms of cost and yield to manufacture a probe having a size that can simultaneously acquire photoacoustic signals of the entire breast. For this reason, for example, Patent Document 1 describes an ultrasonic diagnostic apparatus that reconstructs a three-dimensional image of a wide examination region by mechanically automatically scanning an ultrasonic probe for receiving a photoacoustic signal. .

  On the other hand, a technique for calculating the abundance ratio of substances having different light absorption spectra using photoacoustic signals obtained by irradiating light of a plurality of wavelengths has been studied.

ここで、［ＨｂＯ_２］は酸化ヘモグロビン濃度、［Ｈｂ］は還元ヘモグロビン濃度である。ε_Ｈｂ ^λ１、ε_Ｈｂ ^λ２はそれぞれ波長λ１、λ２における還元ヘモグロビンのモル吸収係数、Δε_Ｈｂ ^λ１、Δε_Ｈｂ ^λ２はそれぞれ波長λ１、λ２における酸化ヘモグロビンのモル吸収係数から還元ヘモグロビンのモル吸収係数を引いた値である。 For example, Non-Patent Document 1 describes a method of calculating oxygen saturation in blood by using a plurality of wavelengths, paying attention to the difference in light absorption spectrum between oxygenated hemoglobin and reduced hemoglobin present in blood. ing.
When the absorption coefficients (μ _a ^λ1 and μ _a ^λ2 ) for the wavelengths λ1 and λ2 at a certain position are used, the oxygen saturation (SO ₂ ) can be calculated by the following equation (1).

Here, [HbO ₂ ] is an oxygenated hemoglobin concentration, and [Hb] is a reduced hemoglobin concentration. ε _Hb ^λ1, ε _Hb ^λ2 each wavelength .lambda.1, minus the molar absorption ^coefficient, Δε _Hb λ1, Δε _Hb ^λ2 respectively wavelengths .lambda.1, the molar absorption coefficient of reduced hemoglobin from the molar absorption coefficient of oxygenated hemoglobin in .lambda.2 of reduced hemoglobin in .lambda.2 Value.

  Patent Document 2 describes an apparatus that measures glucose concentration in blood by irradiating two types of wavelengths.

Japanese Patent No. 4448189 JP 2010-139510 A

Journal of Biomedical Optics 14 (5), 054007

However, when a probe is mechanically scanned and a plurality of wavelengths are irradiated on an observation region of a subject to obtain corresponding photoacoustic signals, movement of the subject that occurs during scanning is a problem. Become.
Consider an imaging time (acoustic wave reception time) when a photoacoustic signal is acquired with an area (240 mm × 180 mm) equivalent to a panel used in general mammography. As an example, assume that the element size is 2 mm square, the number of received CHs is 500 CH, the repetition frequency of light irradiation is 10 Hz, and the average is calculated from 256 measurements in order to improve the SN ratio of the received signal. At this time, to obtain a photoacoustic signal for one wavelength by simple calculation, (240 × 180 × 256) ÷ (2 × 2 × 500 × 10) = 552.96 (seconds), that is, imaging of about 9 minutes Time is required.

As described above, for example, when calculating the oxygen saturation, absorption coefficients for a plurality of wavelengths at a point of interest are used. However, if there is a time difference of about 9 minutes between the time when the photoacoustic signal at the point of interest is acquired at the wavelength λ1 and the time when the photoacoustic signal at the point of interest is acquired at the wavelength λ2, the subject, particularly the living body, is positioned. There is a high possibility that deviation will occur.
When calculating the oxygen saturation at a certain point of interest, it is necessary to use the absorption coefficients of the wavelengths λ1 and λ2 at that point of interest. As described above, when a positional deviation occurs due to the time difference between the data acquisition time point of the wavelength λ1 (acoustic wave reception time point) and the data acquisition time point of the wavelength λ2 (acoustic wave reception time point), the resulting position is different. Therefore, the oxygen saturation is calculated using the absorption coefficient. Then, an error occurs in the calculation result, and reliability and accuracy may be impaired.

  The present invention has been made in view of the above problems, and in an object information acquiring apparatus that acquires photoacoustic signals using light of a plurality of wavelengths, it is possible to suppress the influence of errors due to movement of the object. The purpose is to provide the technology.

  The present invention employs the following configuration. That is, a light source unit that emits pulsed light of a plurality of wavelengths, a wavelength control unit that switches the wavelength of the pulsed light, and a probe that receives acoustic waves that are generated and propagated in the subject irradiated with the pulsed light A scanning control unit that moves the probe in a predetermined scanning range, and a plurality of pulse lights that are output from the probe at each reception position in the scanning range and that correspond to the pulsed light of the plurality of wavelengths. An information processing unit that obtains object information using an electrical signal, and the wavelength control unit includes an acoustic wave corresponding to pulse light having at least one of the plurality of wavelengths. The object information acquiring apparatus is characterized in that the wavelength of the pulsed light is switched before scanning the entire scanning range while receiving at each receiving position.

  ADVANTAGE OF THE INVENTION According to this invention, in the subject information acquisition apparatus which acquires a photoacoustic signal using the light of a several wavelength, the technique which makes it possible to suppress the influence of the error by a motion of a subject can be provided.

The figure which showed typically the concept regarding the data acquisition by several wavelengths. The figure which showed typically the movement of the probe which does not apply this invention. The time chart of the data acquisition which does not apply this invention. The figure which showed typically the movement of the probe of this invention. The time chart of the data acquisition of this invention. The figure which showed the structure of the ultrasonic diagnosing device concerning 1st Embodiment. 1 is a system schematic diagram according to a first embodiment. The figure which showed the structure of the ultrasonic diagnosing device concerning 2nd Embodiment. The figure which showed typically the movement of the probe concerning 2nd Embodiment. The time chart of data acquisition concerning a 2nd embodiment. The figure which showed the structure of the ultrasonic diagnosing device concerning 3rd Embodiment. The figure which showed typically the movement of the probe concerning 3rd Embodiment. The time chart of the data acquisition concerning a 3rd embodiment. The figure which showed the range of the data acquisition of this invention typically. The time chart of the data acquisition of this invention.

Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.
The subject information acquisition apparatus of the present invention receives an acoustic wave (typically an ultrasonic wave) generated in a subject by irradiating the subject with light (electromagnetic wave) and propagated in the subject. This is an apparatus using a photoacoustic effect for acquiring subject information as image data. An acoustic wave generated by the photoacoustic effect is also called a photoacoustic wave. The object information includes, for example, information reflecting the initial sound pressure of the acoustic wave, the light energy absorption density, the absorption coefficient, the concentration of the substance constituting the tissue in the object, and the like derived from the received acoustic wave signal. . Examples of the substance concentration include oxygen saturation, oxy-deoxyhemoglobin concentration, and glucose concentration. The subject information may be acquired as numerical data, or may be acquired as image data indicating distribution information of each position (each attention point) within the subject. That is, it may be acquired as image data indicating distribution information reflecting the oxygen saturation distribution in the subject.

An outline of the photoacoustic signal acquisition operation of the present invention will be described with reference to FIGS.
FIG. 14 is a diagram schematically showing the data acquisition range of the present invention. In the present invention, the “data acquisition range” indicates a predetermined scanning range that includes a plurality of reception positions where the probe receives acoustic waves and that the probe scans to receive a plurality of acoustic waves. The predetermined data acquisition range may be a predetermined range or a range specified every time by the user. When the probe receives an acoustic wave while scanning the data acquisition range, three-dimensional object information such as an oxygen saturation distribution in the object can be acquired as image data. The probe 101 moves in the data acquisition range 105 and receives photoacoustic waves. In the following description, the photoacoustic wave detected by the probe is referred to as a photoacoustic signal.

  Here, for example, consider a case where a photoacoustic signal for pulsed light having two different wavelengths λ 1 and λ 2 is acquired over the data acquisition range 105. When the present invention is not applied, first, the photoacoustic signal for the pulsed light of wavelength λ1 is acquired over the entire data acquisition range 105, and after switching the wavelength, the photoacoustic signal for the pulsed light of wavelength λ2 is extended over the entire data acquisition range 105. Is assumed to be acquired. As shown in FIG. 15A, the operation includes a time 501 for acquiring a photoacoustic signal for pulsed light with a wavelength λ1, and a time 502 for acquiring a photoacoustic signal for pulsed light with a wavelength λ2. If the time required to scan the probe 101 over the entire data acquisition range 105 is T, 2T is required as a whole. Moreover, when the time difference which acquired the photoacoustic signal with respect to a different wavelength is seen, it turns out that there exists a time difference only by T on average.

Next, data acquisition when the present invention is applied will be described. The data acquisition range 105 is divided into a partial data acquisition range 400A and a partial data acquisition range 400B, which are partial areas. The order of data acquisition is as shown in FIG. That is, first, the wavelength λ1 (first wavelength)
The photoacoustic signal for the pulsed light is acquired in the partial data acquisition range 400A (501A), the wavelength is switched, and the photoacoustic signal for the pulsed light of wavelength λ2 (second wavelength) is acquired in the partial data acquisition range 400A (502A). . Next, the wavelength is switched again, the photoacoustic signal for the pulsed light of wavelength λ1 is acquired in the partial data acquisition range 400B (501B), the wavelength is switched, and the photoacoustic signal for the pulsed light of wavelength λ2 is acquired in the partial data acquisition range 400B ( 502B). Assuming that the time required for scanning the probe 101 over the entire data acquisition range 105 is T, 2T is required as a whole as before. However, looking at the time difference at which photoacoustic signals for different wavelengths are acquired, it can be seen that the time difference is only T / 2 on average.
That is, before acquiring the photoacoustic signal obtained by irradiating the pulsed light of one wavelength among the two wavelengths over the entire data acquisition range 105, the wavelength is switched and the photoacoustic signal corresponding to the wavelength is acquired. This means that the wavelength of the pulsed light is switched before the entire data acquisition range (scanning range) is scanned while receiving the acoustic wave corresponding to the pulsed light of one wavelength at each reception position. Thereby, the time difference which acquires the photoacoustic signal with respect to a different wavelength can be shortened. In this case, wavelength switching is performed three times.

  There is also a case as shown in FIG. That is, first, the photoacoustic signal for the pulsed light of wavelength λ1 is acquired in the partial data acquisition range 400A (501A), the wavelength is switched, and the photoacoustic signal for the pulsed light of wavelength λ2 is acquired in the partial data acquisition range 400A (502A). . Next, the photoacoustic signal for the pulsed light of wavelength λ2 was acquired in the partial data acquisition range 400B (502B), the wavelength was switched, and the photoacoustic signal for the pulsed light of wavelength λ1 was acquired in the partial data acquisition range 400B (501B). Is the case. In this case as well, the time difference for acquiring photoacoustic signals for different wavelengths can be shortened. In this case, wavelength switching is performed twice.

When the present invention is applied to acquire photoacoustic signals at N different wavelengths, when the entire data acquisition region is divided into M partial data acquisition ranges (partial regions) (M ≧ 2), the number of times of wavelength switching is increased. The minimum value is (N−1) × M times. In the previous example, since two types of wavelengths are used and divided into two partial data acquisition ranges, (2-1) × 2 = 2 is the minimum number of times.
In addition, the present invention is not applied, and the number of times of wavelength switching (N-1) is used when the wavelength is switched after scanning the entire data acquisition range with one wavelength.
That is, by acquiring all the data (acoustic waves) at all reception positions within the data acquisition range by irradiation with pulse light of N different wavelengths, the wavelength is switched (N−1) × M times,
The time difference for acquiring the photoacoustic signals for different wavelengths can be shortened. That is, errors due to the movement of the subject over time can be suppressed.

(First embodiment)
Hereinafter, embodiments of a biological information processing apparatus according to the present invention will be described in detail with reference to the drawings.
First, the outline and operation of the system in this embodiment will be described, and then the data acquisition operation will be described.

FIG. 6 is a diagram showing a configuration of the peripheral portion of the subject in the ultrasonic diagnostic apparatus according to the first embodiment of the present invention. 6 (a) and 6 (b) are cross-sectional views of the apparatus viewed from a direction perpendicular to the direction in which the subject is compressed, and FIG. 6 (c) is held from the direction in which the subject is compressed. It is the top view which looked at the board.
A subject 104 (referred to as a breast in this embodiment) is held between two holding plates 103 (103a and 103b). The probe 101 is installed on the surface of the holding plate 103a opposite to the breast 104. The light irradiation unit 102 is installed on the surface of the holding plate 103b opposite to the breast 104. As shown in the change from FIG. 6A to FIG. 6B, these probe 101 and light irradiation unit 102 move within the data acquisition range 105.

  The subject does not constitute a part of the subject information acquisition apparatus of the present invention, but will be described below. If the subject information acquisition device is intended for the diagnosis of human or animal malignant tumors or vascular diseases, blood glucose levels, or the follow-up of chemical treatment, in addition to the breast, Parts such as limbs are assumed.

  FIG. 7 is a diagram showing a system outline of the present embodiment. The laser light source unit 204 is a pulsed light (typically about 700 nm to 1100 nm) near the near infrared wavelength according to the timing control signal from the system control unit 201 and the wavelength control signal from the laser wavelength control unit 210. Specifically, 100 nsec or less) is generated. After this pulsed light is transmitted through the optical transmission path, the light irradiation unit 102 passes through the holding plate 103 and irradiates the subject (not shown). Then, the light absorber in the subject absorbs the pulsed light and generates an acoustic wave. In the present invention, light refers to electromagnetic waves including visible light and infrared light. A specific wavelength may be selected according to the component to be measured. The laser wavelength control unit is the wavelength control unit of the present invention, and the laser light source unit is the light source unit of the present invention.

The probe 101 has a plurality of conversion elements, and receives acoustic waves that have passed through the holding plate 103 by the conversion elements and converts them into electrical signals (reception signals). The reception circuit system 205 performs sampling processing and amplification processing on the reception signal output from the probe 101 and converts it into a digital signal (digitized reception signal).
The scanning control unit 211 controls the probe scanning mechanism 202 and the irradiation system scanning mechanism 203 using the data acquisition range information instructed from the system control unit 201, and moves the probe 101 and the light irradiation unit 102. . And the above-mentioned light irradiation and reception of a photoacoustic signal are performed repeatedly.

ここで、ｄＳ_ｏは検出器のサイズ、Ｓ_ｏは再構成に用いた開口のサイズ、ｐ_ｄ（ｒ_ｏ，ｔ）はそれぞれの変換素子で受信された信号、ｒ_ｏはそれぞれの変換素子の位置を、ｔは受信時間を示す。 The reconstruction block 206 performs image reconstruction processing using information such as the probe position input from the system control unit 201 and the digital signal input from the receiving circuit system 205. This image reconstruction is a process of calculating the initial sound pressure distribution p (r) of the photoacoustic wave inside the subject using, for example, FBP (Filtered Back Projection) represented by the following equation (2). .

Here, dS _o is the size of the detector, S _o is the size of the aperture used for reconstruction, p _d (r _o , t) is the signal received by each transducer, and r _o is the size of each transducer The position, t indicates the reception time.

The reconstruction data holding unit 207 holds the initial sound pressure distribution reconstructed with different wavelengths for each wavelength.
The multi-wavelength synthesizing unit 208 receives initial sound pressure distribution data reconstructed with different wavelengths from the reconstructed data holding unit 207 and calculates object information such as oxygen saturation, for example. By properly controlling a plurality of different wavelengths, the glucose concentration can also be calculated. The image display unit 209 displays an image under the control of the system control unit 201. Examples of the displayed image include an image showing an initial sound pressure distribution and an absorption coefficient distribution calculated from a photoacoustic signal acquired at one wavelength, and an oxygen saturation calculated by the multi-wavelength synthesis unit 208.
The processing performed from the reconstruction block to the multi-wavelength synthesis unit corresponds to the processing performed by the information processing unit of the present invention.

Next, acquisition of photoacoustic signals using a plurality of wavelengths will be described with reference to the drawings.
First, FIG. 1 schematically shows a concept regarding data acquisition. The operation of acquiring photoacoustic signals with a plurality of wavelengths will be described with reference to this figure.
Data (acoustic waves) is acquired at each position within the data acquisition range 105 by moving the probe 101 having a plurality of conversion elements. At this time, the probe moves in the data acquisition range by moving in the main scanning direction and in the sub scanning direction a plurality of times. When the movement of the probe is regarded as a raster scan, the main scanning direction is a moving direction along the scanning line, and the probe moves while receiving an acoustic wave at each receiving position. The sub-scanning direction is a moving direction between scanning lines, and is a direction intersecting (typically orthogonal) with the main scanning direction. The partial data acquisition ranges acquired by one movement in the main scanning direction are 110A, 110B, 110C, and 110D, respectively. In the present embodiment, the plurality of partial data acquisition ranges indicate areas in which the data acquisition range that is the scanning range is divided into a plurality of portions in the sub-scanning direction. The partial data acquisition ranges 110A, 110B, 110C, and 110D are regions corresponding to scanning trajectories when the probe is moved while receiving acoustic waves at each reception position in the main scanning direction in the data acquisition range. It is.

  Consider acquiring photoacoustic signals by irradiation of pulsed light having two different wavelengths over the data acquisition range 105. For example, when acquiring photoacoustic signals irradiated with two wavelengths (λ1 and λ2), it is necessary to acquire photoacoustic signals irradiated with two types of wavelengths for each of the four partial data acquisition ranges. .

As a comparison object, an operation when the present invention is not applied will be described with reference to FIG.
First, data (acoustic wave) is acquired by moving within the data acquisition range 105 while irradiating pulsed light of wavelength λ1 (solid arrow). Therefore, the wavelength of the pulsed light is switched to λ2, and the data acquisition range 105 is moved again (broken arrow).

FIG. 3 is a time chart of the partial data acquisition range and irradiation wavelength when such movement is performed. In the figure, A, B, C, and D (301) on the axis with the description of λ1 are light of partial data acquisition ranges (110A, 110B, 110C, and 110D) irradiated with pulsed light of wavelength λ1, respectively. The timing which acquired the acoustic signal is shown. In addition, the notations A, B, C, and D (302) indicate the timings at which the photoacoustic signals in the partial data acquisition ranges (110A, 110B, 110C, and 110D), respectively, irradiated with the pulsed light having the wavelength λ2. . In the moving method described above, all photoacoustic signals are acquired from the data acquisition range 105 by irradiation with pulsed light having one of two different wavelengths.
When such probe scanning is performed, the photoacoustic signal acquisition interval for the wavelength λ1 and the wavelength λ2 for the same partial data acquisition range (for example, 110A) is the length indicated by t1.

FIG. 4 shows a data acquisition operation when the present invention is applied.
First, a wavelength control signal is sent from the laser wavelength control unit 210 to the laser light source 204, and the wavelength is set to λ1. By transmitting a laser irradiation timing control signal from the system control unit 201, the laser light source unit 204 generates pulsed light having a wavelength λ1. The probe 101 and the light irradiation unit 102 are moved in the main scanning direction by a control signal from the scanning control unit 211. In this manner, the photoacoustic signal of the partial data acquisition range 110A for the pulsed light with the wavelength λ1 is acquired (solid arrow of 110A). Subsequently, the probe 101 and the light irradiation unit 102 are moved in the sub-scanning direction to move to the partial data acquisition range 110B. Light irradiation and data acquisition are performed while moving in the main scanning direction within the partial data acquisition range 110B (solid line arrow of 110B). In this way, data in the partial data acquisition ranges 110A and 110B is acquired.

Subsequently, a wavelength control signal is sent from the laser wavelength control unit 210 to the laser light source 204, and the wavelength is set to λ2. Then, the photoacoustic signal with respect to the pulsed light of wavelength (lambda) 2 of partial data acquisition range 110A, 110B, 110C, 110D is acquired (dashed arrow in 110A-110D).
Subsequently, a wavelength control signal is sent again from the laser wavelength control unit 210 to the laser light source unit 204, and the wavelength is set to λ1. Thereafter, a photoacoustic signal for the pulsed light having the wavelength λ1 in the partial data acquisition ranges 110C and 110D is acquired.

FIG. 5 is a time chart of the partial data acquisition range and irradiation wavelength when such movement is performed. Wavelength switching is performed on two dotted lines between the axis of λ1 and the axis of λ2, that is, wavelength switching is performed twice. That is, at each reception position in the scanning range, the probe outputs a plurality of electrical signals respectively corresponding to pulsed light having a plurality of wavelengths.
In the probe scanning in the present embodiment, before acquiring all the photoacoustic signals from within the data acquisition range 105 by irradiation with pulsed light having one of two different wavelengths (for example, λ1), The wavelength is switched. Of the plurality of movements in the main scanning direction (eight times), the second main scanning direction movement and the sixth main scanning direction movement are completed. The wavelength is switched.

In the probe scanning in this embodiment, the acquisition interval of the photoacoustic signals related to the wavelengths λ1 and λ2 in the same partial data acquisition range 110A is the length indicated by t2. As described above, the length of this acquisition interval is compared with the case of acquiring the photoacoustic signal for the pulsed light irradiation of the wavelength λ2 after acquiring the photoacoustic signal for the pulsed light irradiation of the wavelength λ1 in the entire data acquisition range 105 as described above. Short. In the present embodiment, t2 is half the length of t1.
Therefore, according to the present embodiment, it is possible to suppress errors due to the movement of the subject over time. Therefore, when calculating oxygen saturation using received signals corresponding to two wavelengths (λ1, λ2), it is possible to suppress errors due to misalignment and to construct highly reliable and highly accurate images. It is. In this embodiment, two initial sound pressure distributions corresponding to two wavelengths are obtained in advance, and then the oxygen saturation distribution is obtained. However, when an acoustic wave is received without obtaining the initial sound pressure distribution. It is also possible to obtain oxygen saturation or the like using an electric signal (received signal) output from the probe.

  In this embodiment, the data acquisition of the partial data acquisition range is completed by one movement in the main scanning direction. However, in order to obtain a necessary signal S / N ratio, the pulse light of the same wavelength is irradiated in the main scanning direction. You may move several times. For example, the effect of the present invention can be obtained in the same manner even if control is performed to move in the sub-scanning direction after one reciprocation in the main scanning direction.

(Second Embodiment)
FIG. 8 is a diagram showing a configuration of a peripheral portion of a subject in an ultrasonic diagnostic apparatus according to the second embodiment of the present invention. FIG. 8A is a cross-sectional view of the apparatus viewed from a direction perpendicular to the direction in which the subject is compressed, and FIG. 8B is a plan view of the holding plate viewed from the direction in which the subject is compressed. It is.
A subject 104 (referred to as a breast in this embodiment) is held between two holding plates 103 (103a and 103b). The probe 101 is installed on the surface of the holding plate 103a opposite to the breast 104. The light irradiation unit 102 is installed on the surface of the holding plate 103b opposite to the breast 104. The probe 101 and the light irradiation unit 102 move so as to acquire data in the data acquisition range 105.

The probe 101 moves with a circumferential direction 801 centered on a virtual axis 803 in the subject as a main scanning direction and a direction 802 substantially perpendicular to the main scanning direction as a sub scanning direction.
Further, in order to receive acoustic waves that pass through the holding plate 103, a medium (for example, water or castor oil) that transmits ultrasonic waves is filled between the probe 101 and the holding plate 103.

Since the outline of the system and the flow of data processing are the same as those in the first embodiment, description thereof will be omitted, and acquisition of photoacoustic signals with a plurality of wavelengths will be described with reference to the drawings.
FIG. 9 shows the data acquisition operation performed in this embodiment. As described above, the main scanning direction is a circumferential direction centered on a virtual axis 803, but here, for explanation, the description will be made with a two-dimensional drawing in which the circumferential direction is developed on a plane.

In this embodiment, a case where three different wavelengths are used will be described.
First, the wavelength is set to λ1, and the probe 101 is moved in the main scanning direction to acquire a photoacoustic signal for the pulsed light having the wavelength λ1 in the partial data acquisition range 110A (solid line arrow). Next, after switching to wavelength λ2, a photoacoustic signal for pulsed light of wavelength λ2 in partial data acquisition range 110A is acquired (broken arrow). Further, after switching to the wavelength λ3, a photoacoustic signal for the pulsed light with the wavelength λ3 in the partial data acquisition range 110A is acquired (arrow with a dashed line). Thereafter, the data moves in the sub-scanning direction, and data in the partial data acquisition range 110B is acquired. This operation is repeated to acquire data up to the partial data acquisition range 110D.
As described above, the movement in the main scanning direction is performed a plurality of times (at least twice, in this embodiment, three times) before moving in the sub-scanning direction, and any one of them is moved in the main scanning direction. At the time of completion, control to change the wavelength is performed.

  FIG. 10 is a time chart of the partial data acquisition range and irradiation wavelength in the present embodiment. In the probe scanning in this embodiment, the acquisition interval of the photoacoustic signals related to the wavelengths λ1 and λ3 in the same partial data acquisition range 110A is the length indicated by t3. The length of the acquisition interval is significantly larger than that in the case where the photoacoustic signal for the pulsed light irradiation with the wavelength λ2 and the wavelength λ3 is acquired after the photoacoustic signal for the pulsed light irradiation with the wavelength λ1 is acquired in the entire data acquisition range 105. Shortened to In this embodiment, the time difference is shortened to 1/4 compared with the case where the present invention is not applied.

According to the present embodiment, since wavelength switching and main scanning direction movement are performed a plurality of times before moving in the sub-scanning direction, the acquisition interval of photoacoustic signals for different wavelengths in the same partial data acquisition range can be further shortened. That is, it is possible to further suppress errors due to the movement of the subject over time.
For this reason, when data reconstructed from photoacoustic signals acquired with multiple wavelengths (λ1, λ2, λ3) is used, and oxygen saturation is calculated by the multiwavelength synthesis unit, errors due to misalignment are further suppressed. In addition, it is possible to construct a highly reliable image with high reliability.

  In the present embodiment, the main scanning direction is defined in the circumferential direction around the virtual axis. However, even when the probe is scanned two-dimensionally as in the spatial arrangement of the first embodiment. The effects of the present invention can be obtained.

(Third embodiment)
FIG. 11 is a diagram showing a configuration of a peripheral portion of a subject of an ultrasonic diagnostic apparatus according to the third embodiment of the present invention. FIG. 11A is a view of a subject to be dropped from above, and FIG. 11B is a view of a subject to be dropped from the side.
A subject (in this embodiment, a breast) 104 is drooped. The probe 101 and the light irradiation unit 102 are installed at positions facing each other with the subject 104 interposed therebetween. The probe 101 and the light irradiation unit 102 move so as to acquire data in the data acquisition range.

The probe 101 moves with a circumferential direction 801 centered on a virtual axis 803 in the subject as a main scanning direction and a direction 802 substantially perpendicular to the main scanning direction as a sub scanning direction. In this embodiment, the data acquisition range is a range obtained by moving the surface of the probe 101 rotated 360 degrees with respect to the virtual axis 803 in the sub-scanning direction.
Further, in order to receive the photoacoustic wave generated in the subject 104, the probe 101 and the subject 104 are filled with a medium (for example, water or castor oil) that transmits ultrasonic waves.

Since the outline of the system and the flow of data processing are the same as those in the first embodiment, description thereof will be omitted, and acquisition of photoacoustic signals with a plurality of wavelengths will be described with reference to the drawings.
FIG. 12 shows the data acquisition operation performed in this embodiment. As described above, the main scanning direction is a circumferential direction centered on a virtual axis 803, but here, for explanation, the description will be made with a two-dimensional drawing in which the circumferential direction is developed on a plane. That is, the right end and the left end of the data acquisition range 105 in FIG. 12 are spatially connected.

First, the probe 101 is rotated 360 degrees about the virtual axis 803 (centering arrow 150A). The wavelength is switched during the movement in the main scanning direction. In this embodiment, the wavelength is switched for each pulse. In other words, λ1, λ2, λ1, λ2,. In order to change the wavelength of the pulsed light generated by the laser light source at high speed, two lasers may be used alternately.
By performing such an operation, it is possible to acquire a photoacoustic signal for the pulsed light with the wavelength λ1 and the pulsed light with the wavelength λ2 in the partial data acquisition range 110A. When the probe 101 rotates 360 degrees about the virtual axis 803, the probe 101 is moved in the sub-scanning direction, and again rotates 360 degrees about the virtual axis 803 (centering arrow 150B) to obtain partial data. Data in range 110B is acquired. Data acquisition is similarly performed for the partial data acquisition ranges 110C and 110D.
Thus, during the movement in the main scanning direction, control is performed to switch the wavelength of the pulsed light generated from the laser light source unit, and data in the data acquisition range is acquired.

  FIG. 13 is a time chart of the irradiation wavelength in this embodiment. The range of 160A schematically represents a period during which the wavelength is switched for each pulse and the photoacoustic signal is acquired for the pulsed light of wavelength λ1 and the pulsed light of wavelength 2 in the partial data acquisition range 110A. . The partial data acquisition ranges 110B, 110C, and 110D correspond to the ranges 160B, 160C, and 160D, respectively.

  In the probe scanning in this embodiment, the acquisition interval of the photoacoustic signal for the wavelength λ1 and the wavelength λ2 in the same partial data acquisition range is the length indicated by t4. The length of this acquisition interval is greatly reduced compared to the case of acquiring the photoacoustic signal for the pulsed light irradiation of the wavelength λ2 after acquiring the photoacoustic signal for the pulsed light irradiation of the wavelength λ1 in the entire data acquisition range. .

According to this embodiment, since wavelength switching is performed while moving in the main scanning direction, the acquisition interval of photoacoustic signals for different wavelengths in the same partial data acquisition range can be further shortened. That is, it is possible to further suppress errors due to the movement of the subject over time.
Therefore, when using data reconstructed from photoacoustic signals acquired by a plurality of wavelengths (λ1, λ2), and further calculating oxygen saturation and the like in the multiwavelength synthesis unit, errors due to misalignment are further suppressed, It is possible to construct a highly reliable image with high reliability.

In the present embodiment, wavelength switching and photoacoustic signal acquisition are performed while continuously moving the probe in the main scanning direction. That is, in the movement in the main scanning direction, the probe does not stop at each reception position and moves at a substantially constant speed. Therefore, as shown in FIG. 13, the acquisition position (reception position) of the photoacoustic signal when the light of wavelength λ1 is irradiated and the acquisition position when the light of wavelength λ2 is irradiated do not exactly match. . However, if the frequency of the pulsed light is sufficiently high, it is possible to proceed by assuming that there is almost no displacement of the acquisition position. Even if there is a deviation in the photoacoustic signal acquisition position corresponding to each pulsed light, the reconstruction block 206 calculates image data of a certain area within the partial data acquisition range, so that image reconstruction for the same position is performed. It can be performed.
Alternatively, the probe may be temporarily stopped at a position on the subject to receive a photoacoustic signal using light having wavelengths λ1 and λ2, and then moved to the next position. In this case, it is possible to acquire a photoacoustic signal having almost no time difference at the same reception position with respect to the subject.

  In this embodiment, the main scanning direction is defined in the circumferential direction around the virtual axis. However, even when the probe is scanned two-dimensionally as in the spatial arrangement of the first embodiment. The effects of the present invention can be obtained.

  101: Probe, 102: Light irradiation unit, 105: Data acquisition range, 110A to 110D: Partial data acquisition range, 201: System control unit, 202: Probe scanning mechanism, 204: Laser light source unit, 205: Reception Circuit system 206: Reconfiguration block 207: Reconfiguration data holding unit 208: Multi-wavelength synthesis unit 210: Laser wavelength control unit 211: Scan control unit

The present invention employs the following configuration. That is, a light source unit that emits pulsed light of a plurality of wavelengths, a wavelength control unit that switches the wavelength of the pulsed light, and a probe that receives acoustic waves that are generated and propagated in the subject irradiated with the pulsed light A scanning control unit that moves the probe in a predetermined scanning range, and a plurality of pulse lights that are output from the probe at each reception position in the scanning range and that correspond to the pulsed light of the plurality of wavelengths. An information processing unit for obtaining object information using an electrical signal, and the light source unit is different from the first light source unit for irradiating pulsed light of a first wavelength and the first wavelength. A second light source unit that emits pulsed light of two wavelengths, and the wavelength control unit, before the probe acquires all the electrical signals corresponding to the pulsed light of the first wavelength, switching the wavelength of the pulsed light to the second wavelength A subject information obtaining apparatus according to claim.

Claims (6)

A light source unit that emits pulsed light of a plurality of wavelengths;
A wavelength controller that switches the wavelength of the pulsed light;
A probe for receiving an acoustic wave generated and propagated in the subject irradiated with the pulsed light; and
A scanning control unit for moving the probe in a predetermined scanning range;
An information processing unit for obtaining object information using a plurality of electrical signals corresponding to the pulsed light of the plurality of wavelengths output from the probe at each reception position in the scanning range;
Have
The wavelength control unit, before the probe scans the entire scanning range while receiving acoustic waves corresponding to pulsed light of at least one wavelength among the plurality of wavelengths at each reception position, 2. A subject information acquiring apparatus that switches the wavelength of the pulsed light. The scanning control unit moves the probe in a main scanning direction, which is a direction in which the probe moves while receiving acoustic waves at each reception position, and a sub-scanning direction that intersects the main scanning direction. The object information acquiring apparatus according to claim 1, wherein acoustic wave reception in a range is enabled. The scanning range is divided into a plurality of partial areas in the sub-scanning direction,
The wavelength control unit receives the acoustic wave corresponding to the pulsed light of the first wavelength at each reception position in the at least one partial region of the plurality of partial regions, and then in the other partial regions. The object information acquiring apparatus according to claim 2, wherein the wavelength of the pulsed light is switched to a second wavelength different from the first wavelength before receiving an acoustic wave. The partial area corresponds to a scanning trajectory when the probe is moved while receiving an acoustic wave at each reception position in the main scanning direction in the scanning range,
The scanning control unit moves the probe a plurality of times in the partial area,
The object information acquiring apparatus according to claim 3, wherein the wavelength control unit switches the wavelength of the pulsed light so that pulsed light having different wavelengths is irradiated in the plurality of movements. The partial area corresponds to a scanning trajectory when the probe is moved while receiving an acoustic wave at each reception position in the main scanning direction in the scanning range,
The object information acquiring apparatus according to claim 3, wherein the wavelength controller switches the wavelength of the pulsed light while the probe is moving in the main scanning direction in the partial region. The object information acquiring apparatus according to claim 5, wherein the wavelength control unit switches a wavelength of the pulsed light for each irradiation of the pulsed light.

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