JP6636092B2 - Subject information acquisition device - Google Patents

Description

  The present invention relates to a subject information acquisition device.

2. Description of the Related Art Conventionally, an X-ray mammography apparatus is known as a powerful image diagnostic apparatus for finding and diagnosing breast cancer. In recent years, a technique of transmitting light energy into a subject, receiving a photoacoustic signal generated as a result of thermal expansion due to absorption of the light energy, and imaging the inside of the subject based on the photoacoustic signal has attracted attention. I have. The photoacoustic signal is an acoustic wave such as an ultrasonic wave, and is particularly 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 electric signal using a conversion element such as a piezoelectric element or a CMUT (Capacitive Micromachined Ultrasonic Transducer) manufactured using a semiconductor technology. In practice, a probe in which a plurality of such conversion elements are arranged is often used.

  However, it is difficult to manufacture a probe having a size sufficient to simultaneously acquire a photoacoustic signal of the entire breast in terms of cost and yield. For this reason, for example, Patent Literature 1 discloses an ultrasonic diagnostic apparatus that automatically and mechanically scans an ultrasonic probe for receiving a photoacoustic signal to reconstruct a three-dimensional image of a wide inspection area. .

  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 focuses on the point that light absorption spectra differ between oxyhemoglobin and reduced hemoglobin present in blood, and describes a method of calculating oxygen saturation in blood by using a plurality of wavelengths. ing.
At a location, the wavelength .lambda.1, the absorption coefficient for ^{_{λ2 (μ a λ1, μ a}} λ2) With 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 discloses an apparatus that measures glucose concentration in blood by irradiating two kinds of wavelengths.

Japanese Patent No. 4448189 JP 2010-139510 A

Journal of Biomedical Optics 14 (5), 054007

However, when a probe is mechanically scanned to irradiate an observation region of a subject with a plurality of wavelengths and acquire photoacoustic signals corresponding to the respective wavelengths, movement of the subject occurring during scanning poses a problem. Become.
Consider an imaging time (acoustic wave reception time) when acquiring a photoacoustic signal with a width (240 mm × 180 mm) equivalent to a panel used in general mammography. As an example, it is assumed that the element size is 2 mm square, the number of received channels is 500 CH, the repetition frequency of light irradiation is 10 Hz, and the average is calculated from 256 measurements 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 for about 9 minutes It takes time.

As described above, for example, when calculating the oxygen saturation, the absorption coefficients for a plurality of wavelengths at the point of interest are used. However, if there is a time difference of about 9 minutes between the time when the photoacoustic signal of the target point is acquired at the wavelength λ1 and the time when the photoacoustic signal of the target point is acquired at the wavelength λ2, the subject, particularly the living body, is located. Is likely to occur.
When calculating the oxygen saturation or the like at a certain point of interest, it is necessary to use the absorption coefficients of the wavelengths λ1 and λ2 at the point of interest. As described above, if the position shift occurs due to the time difference between the data acquisition time point of the wavelength λ1 (the reception time point of the acoustic wave) and the data acquisition time point of the wavelength λ2 (the reception time of the acoustic wave), a different position results. The oxygen saturation is calculated using the absorption coefficient in the above. Then, an error may occur 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 acquisition apparatus that acquires a photoacoustic signal using light of a plurality of wavelengths, it is possible to suppress the influence of an error due to the movement of the object. The purpose is to provide a technology.

The present invention employs the following configuration. That is, a light irradiating unit that irradiates a plurality of wavelengths of pulsed light, information on a data acquisition region that is a target for acquiring subject information and includes a plurality of divided regions, and a timing of irradiating the pulsed light are controlled. A timing control signal, a system control unit that outputs, a wavelength control unit that switches the wavelength of the pulse light based on the timing control signal, and an acoustic wave generated and propagated in the subject irradiated with the pulse light. and incoming probe, wherein said probe based on the data acquisition area information by changing the relative position between the subject before Symbol scanning control for scanning the probe relative to the object parts and the probe is output from the probe at each receiving location of said data acquisition area to be scanned, each of the plurality of electrical signals corresponding to the pulsed light of said plurality of wavelengths And an information processing unit for obtaining object information about the plurality of wavelengths based, has, the wavelength control unit, the period the probe the divided region is scanned, or, among the plurality of divided regions An object information acquiring apparatus, wherein a wavelength of the pulse light irradiating the object is switched during a period in which the probe moves .
Another embodiment of the present invention employs the following configuration. That is, an area acquisition step of acquiring information on a data acquisition area which is a target for acquiring object information and includes a plurality of divided areas, and irradiates the object with pulsed light of a plurality of wavelengths in the data acquisition area. A light irradiation step, a reception step of receiving an acoustic wave generated and propagated in the object irradiated with the pulsed light by a probe and outputting an electric signal, and in the data acquisition region, the probe and the by changing the relative position between the subject, Te before Symbol a scanning step of scanning the probe relative to the subject, each receiving location odor of the data acquisition region wherein probe scans includes, an information processing step of obtaining object information about the plurality of wavelengths based on each of a plurality of said electrical signals corresponding to the pulsed light of said plurality of wavelengths, in the light irradiation step, the dividing During the period in which the probe scans an area, or during the period in which the probe moves between the plurality of divided regions, the wavelength of the pulsed light to irradiate the subject based on the change in the relative position. This is a subject information acquisition method characterized by switching .

  ADVANTAGE OF THE INVENTION According to this invention, in the subject information acquisition apparatus which acquires a photoacoustic signal using the light of several wavelengths, the technique which can suppress the influence of the error by the movement 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. 6 is a time chart of data acquisition to which the present invention is not applied. The figure which showed typically the movement of the probe of this invention. 4 is a time chart of data acquisition according to the present invention. FIG. 1 is a diagram showing a configuration of an ultrasonic diagnostic apparatus according to a first embodiment. FIG. 1 is a schematic diagram of a system according to a first embodiment. FIG. 6 is a diagram illustrating a configuration of an ultrasonic diagnostic apparatus according to a second embodiment. The figure which showed typically the movement of the probe concerning 2nd Embodiment. 9 is a time chart of data acquisition according to the second embodiment. FIG. 7 is a diagram illustrating a configuration of an ultrasonic diagnostic apparatus according to a third embodiment. The figure which showed typically the movement of the probe concerning 3rd Embodiment. 9 is a time chart of data acquisition according to the third embodiment. The figure which showed typically the range of the data acquisition of this invention. 4 is a time chart of data acquisition according to the present invention.

Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.
The subject information acquiring 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 utilizing the photoacoustic effect of acquiring subject information as image data. The acoustic wave generated by the photoacoustic effect is also called a photoacoustic wave. The subject information includes initial sound pressure of the acoustic wave, light energy absorption density, absorption coefficient, information reflecting the concentration of a substance constituting a tissue in the subject, and the like, which are derived from the received signal of the acoustic wave. . The substance concentration is, for example, oxygen saturation, oxy-deoxyhemoglobin concentration, glucose concentration and the like. In addition, the subject information may be obtained as numerical data, or may be obtained as image data indicating distribution information of each position (each point of interest) in the subject. That is, the image data may be acquired as image data indicating distribution information reflecting the oxygen saturation distribution in the subject.

The 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 a data acquisition range according to the present invention. In the present invention, the “data acquisition range” includes a plurality of reception positions where the probe receives acoustic waves, and indicates a predetermined scanning range in which the probe scans to receive a plurality of acoustic waves. This predetermined data acquisition range may be a predetermined range or a range designated each time by the user. When the probe receives an acoustic wave while scanning within the data acquisition range, it is possible to acquire three-dimensional subject information such as oxygen saturation distribution in the subject as image data. The probe 101 moves within the data acquisition range 105 and receives a photoacoustic wave. In the following description, such a photoacoustic wave detected by the probe is referred to as a photoacoustic signal.

  Here, for example, a case where a photoacoustic signal for pulse light having two different wavelengths λ1 and λ2 is acquired over the data acquisition range 105 is considered. When the present invention is not applied, first, a photoacoustic signal for the pulse light of the wavelength λ1 is acquired in the entire data acquisition range 105, and after switching the wavelength, the photoacoustic signal for the pulse light of the wavelength λ2 is acquired in the entire data acquisition range 105. Assume the operation of acquiring As shown in FIG. 15A, the operation includes a time 501 for acquiring a photoacoustic signal for the pulse light having the wavelength λ1 and a time 502 for acquiring the photoacoustic signal for the pulse light having the wavelength λ2. Assuming that the time required to scan the probe 101 over the entire data acquisition range 105 is T, a total time of 2T is required. Also, looking at the time difference when the photoacoustic signals for the different wavelengths are acquired, it can be seen that there is a time difference of 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, wavelength λ1 (first wavelength)
A photoacoustic signal corresponding to the pulse light is acquired in the partial data acquisition range 400A (501A), the wavelength is switched, and a photoacoustic signal corresponding to the pulse light having the wavelength λ2 (second wavelength) is acquired in the partial data acquisition range 400A (502A). . Next, the wavelength is switched again, a photoacoustic signal for the pulse light of wavelength λ1 is acquired in the partial data acquisition range 400B (501B), and the wavelength is switched, and a photoacoustic signal for the pulse light of wavelength λ2 is acquired in the partial data acquisition range 400B ( Step 502B). Assuming that the time required to scan the probe 101 over the entire data acquisition range 105 is T, a total time of 2T is required as in the case described above. However, looking at the time difference when the photoacoustic signals for the different wavelengths are obtained, it can be seen that the time difference is only T / 2 on average.
That is, before acquiring a photoacoustic signal obtained by irradiating pulsed light of one wavelength out of two wavelengths over the entire data acquisition range 105, the wavelength is switched and a photoacoustic signal based on the wavelength is acquired. This means that the wavelength of the pulse light is switched before the entire data acquisition range (scanning range) is scanned while receiving the acoustic wave corresponding to the pulse light of one wavelength at each reception position. As a result, it is possible to reduce the time difference between acquiring photoacoustic signals for different wavelengths. In this case, wavelength switching is performed three times.

  There is also a case as shown in FIG. That is, first, a photoacoustic signal for the pulse light of wavelength λ1 is acquired in the partial data acquisition range 400A (501A), the wavelength is switched, and a photoacoustic signal for the pulse light of wavelength λ2 is acquired in the partial data acquisition range 400A (502A). . Next, a photoacoustic signal for the pulse light of wavelength λ2 was acquired in the partial data acquisition range 400B (502B), the wavelength was switched, and a photoacoustic signal for the pulse 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 similarly reduced. In this case, the wavelength is switched twice.

When photoacoustic signals are acquired at N different wavelengths by applying the present invention, if the entire data acquisition area is divided into M partial data acquisition ranges (partial areas) (M ≧ 2), the number of wavelength switching times can be reduced. The minimum value is (N-1) × M times. In the above example, since two types of wavelengths are used to divide the data into two partial data acquisition ranges, (2-1) × 2 = 2 is the minimum number of times.
In addition, the number of wavelength switching (N-1) times when the wavelength is switched after scanning the entire data acquisition range with one wavelength without applying the present invention is obtained.
In other words, by irradiating pulse light of N different wavelengths, the wavelength is switched (N−1) × M times before all data (acoustic waves) are acquired at all reception positions within the data acquisition range.
It is possible to reduce the time difference between acquiring photoacoustic signals for different wavelengths. 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 according to the present embodiment will be described, and then the data acquisition operation will be described.

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

  The subject does not constitute a part of the subject information acquiring apparatus of the present invention, but will be described below. If it is a subject information acquisition device for the purpose of diagnosing human or animal malignant tumors and vascular diseases, blood glucose level, etc. Parts such as limbs are assumed.

  FIG. 7 is a diagram schematically illustrating a system according to the present embodiment. The laser light source unit 204 generates pulsed light (typically about 700 nm to 1100 nm) of near-infrared wavelength (typically, 700 nm to 1100 nm) according to the timing control signal from the system control unit 201 and the wavelength control signal from the laser wavelength control unit 210. (Less than 100 nsec). After being transmitted by the optical transmission path, the pulse light is transmitted from the light irradiation unit 102 to the subject (not shown) through the holding plate 103. Then, the light absorber in the subject absorbs the pulse light and generates an acoustic wave. In the present invention, light refers to electromagnetic waves including visible light and infrared light. It is preferable to select a specific wavelength according to the component to be measured. The laser wavelength controller is the wavelength controller of the present invention, and the laser light source is the light source of the present invention.

The probe 101 has a plurality of conversion elements, and receives the acoustic waves that have passed through the holding plate 103 with the conversion elements and converts the acoustic waves into electric signals (received signals). The receiving circuit system 205 performs sampling processing and amplification processing on the received signal output from the probe 101 and converts the signal into a digital signal (digitized received 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 by the system control unit 201 to move the probe 101 and the light irradiation unit 102. . Then, the light irradiation and the reception of the photoacoustic signal are repeatedly performed.

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 an image reconstruction process using information such as a probe position input from the system control unit 201 and a digital signal input from the receiving circuit system 205. The 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) expressed 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 conversion element, and r _o is the size of the conversion element. The position indicates the reception time.

The reconstructed data holding unit 207 holds the initial sound pressure distribution reconstructed by different wavelengths for each wavelength.
The multi-wavelength synthesizing unit 208 receives the initial sound pressure distribution data reconstructed at different wavelengths from the reconstructed data holding unit 207, and calculates subject information such as oxygen saturation by calculating. By appropriately 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. The displayed image includes, for example, an image showing an initial sound pressure distribution and an absorption coefficient distribution calculated from a photoacoustic signal acquired at one wavelength, an oxygen saturation calculated by the multi-wavelength synthesis unit 208, and the like.
The processing performed from the reconstructed block to the multi-wavelength synthesizing unit corresponds to the processing performed by the information processing unit of the present invention.

Next, acquisition of a photoacoustic signal 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 a photoacoustic signal with a plurality of wavelengths will be described with reference to FIG.
As the probe 101 having a plurality of conversion elements moves, data (acoustic waves) is acquired at each position within the data acquisition range 105. At this time, the probe moves within the data acquisition range by performing a plurality of movements in the main scanning direction and a plurality of movements in the sub-scanning direction. When the movement of the probe is viewed as a raster scan, the main scanning direction is a moving direction along a scanning line, and is a direction in which the probe moves while receiving an acoustic wave at each reception position. The sub-scanning direction is a direction of movement 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 defined as 110A, 110B, 110C, and 110D, respectively. In the present embodiment, the plurality of partial data acquisition ranges indicate regions in which the data acquisition range, which is the scanning range, is divided into a plurality in the sub-scanning direction. Each of the partial data acquisition ranges 110A, 110B, 110C, and 110D is an area corresponding to a scanning trajectory when the probe is moved in the main scanning direction while receiving an acoustic wave at each reception position in the data acquisition range. It is.

  It is assumed that photoacoustic signals obtained by irradiation with pulsed light having two different wavelengths are acquired over the data acquisition range 105. For example, when acquiring photoacoustic signals radiated at two wavelengths (referred to as λ1 and λ2), it is necessary to acquire photoacoustic signals radiated at two wavelengths for each of the four partial data acquisition ranges. .

As a comparison target, an operation when the present invention is not applied will be described with reference to FIG.
First, data (acoustic waves) are acquired by moving within the data acquisition range 105 while irradiating pulse light of the wavelength λ1 (solid arrow). Therefore, the wavelength of the pulse 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 the irradiation wavelength when such a movement is performed. In the drawing, A, B, C, and D (301) on the axis with λ1 are light beams of partial data acquisition ranges (110A, 110B, 110C, and 110D) irradiated with pulse light of wavelength λ1. The timing at which the acoustic signal was obtained is shown. 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, 110D) irradiated with pulse light of the wavelength λ2 are obtained. . In the moving method described above, all photoacoustic signals are acquired from within the data acquisition range 105 by irradiation with pulsed light of one of two different wavelengths.
When such a probe scan is performed, the acquisition interval of the photoacoustic signals for the wavelengths λ1 and λ2 in 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 controller 210 to the laser light source 204 to set the wavelength to λ1. By transmitting a laser irradiation timing control signal from the system control unit 201, the laser light source unit 204 generates pulse light having the 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 way, a photoacoustic signal of the partial data acquisition range 110A for the pulse light of 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 and moved to the partial data acquisition range 110B. Then, light irradiation and data acquisition are performed while moving in the main scanning direction within the partial data acquisition range 110B (solid arrow in 110B). Thus, the data of the partial data acquisition ranges 110A and 110B are acquired.

Subsequently, a wavelength control signal is sent from the laser wavelength controller 210 to the laser light source 204, and the wavelength is set to λ2. Thereafter, a photoacoustic signal is acquired for the pulse light of the wavelength λ2 in the partial data acquisition ranges 110A, 110B, 110C, 110D (broken arrows in 110A to 110D).
Subsequently, a wavelength control signal is sent again from the laser wavelength control unit 210 to the laser light source unit 204 to set the wavelength to λ1. After that, a photoacoustic signal is acquired for the pulse light of the wavelength λ1 in the partial data acquisition ranges 110C and 110D.

FIG. 5 is a time chart of the partial data acquisition range and the irradiation wavelength when such movement is performed. The wavelength switching is performed at the two dotted lines between the axis of λ1 and the axis of λ2, that is, the wavelength switching is performed twice. That is, at each reception position in the scanning range, the probe outputs a plurality of electric signals respectively corresponding to pulse lights of a plurality of wavelengths.
The probe scanning according to the present embodiment is performed by irradiating pulse light of one of two different wavelengths (for example, λ1) before acquiring all the photoacoustic signals from within the data acquisition range 105. Switching wavelength. Further, at the time when the second movement in the main scanning direction and the sixth movement in the main scanning direction out of the plurality of movements (eight times) in the main scanning direction are completed, the pulse light generated from the laser light source unit 204 ends. Switching wavelength.

In the probe scanning according to the present embodiment, the acquisition interval of the photoacoustic signals for the wavelengths λ1 and λ2 of the same partial data acquisition range 110A is the length indicated by t2. As described above, the length of the acquisition interval is different from the case where the photoacoustic signal for the pulsed light irradiation of the wavelength λ1 is acquired in the entire data acquisition range 105 and then the photoacoustic signal for the pulsed light irradiation of the wavelength λ2 is acquired. And short. In the present embodiment, t2 is half the length of t1.
Therefore, according to the present embodiment, it is possible to suppress an error due to the movement of the subject over time. Therefore, when calculating the oxygen saturation or the like using the reception signals corresponding to the two wavelengths (λ1, λ2), it is possible to suppress an error due to a displacement and to construct a highly reliable and highly accurate image. It is. In the present embodiment, the oxygen saturation distribution is obtained after the two initial sound pressure distributions corresponding to the two wavelengths are obtained in advance, but when the acoustic wave is received without obtaining the initial sound pressure distribution. The oxygen saturation and the like can also be obtained using an electric signal (received signal) output from the probe.

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

(Second embodiment)
FIG. 8 is a diagram showing a configuration of a peripheral part of a subject in the ultrasonic diagnostic apparatus according to the second embodiment of the present invention. 8A is a cross-sectional view of the apparatus viewed from a direction perpendicular to the direction in which the subject is pressed, and FIG. 8B is a plan view of the holding plate viewed from the direction in which the subject is pressed. It is.
A subject (in this embodiment, a breast) 104 is held between two holding plates 103 (103a, 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 provided on a 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 in a circumferential direction 801 around 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 the acoustic wave transmitted through the holding plate 103, the medium between the probe 101 and the holding plate 103 is filled with a medium (for example, water or castor oil) for transmitting ultrasonic waves.

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

In the present 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 pulse light of the wavelength λ1 in the partial data acquisition range 110A (solid arrow). Next, after switching to the wavelength λ2, a photoacoustic signal is acquired for the pulse light of the wavelength λ2 in the partial data acquisition range 110A (dashed arrow). Further, after switching to the wavelength λ3, a photoacoustic signal is acquired for the pulse light of the wavelength λ3 in the partial data acquisition range 110A (dotted line arrow). After that, it moves in the sub-scanning direction and acquires data in the partial data acquisition range 110B. 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 two times, in this embodiment, three times) before the movement in the sub-scanning direction, and any one of the movements in the main scanning direction is performed. At the time of completion, control for changing the wavelength is performed.

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

According to the present embodiment, since the wavelength switching and the movement in the main scanning direction 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 reduced. That is, it is possible to further suppress an error due to the movement of the subject over time.
Therefore, when data reconstructed from the photoacoustic signals obtained at a plurality of wavelengths (λ1, λ2, λ3) is used and the oxygen saturation and the like are calculated in the multi-wavelength synthesis unit, errors due to positional deviation are further suppressed. In addition, a highly reliable and highly accurate image can be constructed.

  In the present embodiment, the main scanning direction is defined in the circumferential direction about 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 part of a subject in the ultrasonic diagnostic apparatus according to the third embodiment of the present invention. FIG. 11A is a diagram of a drooping subject viewed from above, and FIG. 11B is a diagram of a drooping subject viewed from the side.
The subject (in this embodiment, the breast) 104 is dropped. The probe 101 and the light irradiation unit 102 are installed at positions facing each other across the subject 104. The probe 101 and the light irradiation unit 102 move so as to acquire data in a data acquisition range.

The probe 101 moves in a circumferential direction 801 around 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 the present embodiment, the data acquisition range is a range in which the plane on which the probe 101 is rotated by 360 degrees with respect to the virtual axis 803 is moved in the sub-scanning direction.
Further, in order to receive a photoacoustic wave generated in the subject 104, the space between the probe 101 and the subject 104 is filled with a medium (for example, water or castor oil) for transmitting ultrasonic waves.

Since the outline of the system and the flow of data processing are the same as those in the first embodiment, a description thereof will be omitted, and acquisition of a photoacoustic signal using a plurality of wavelengths will be described using the drawings.
FIG. 12 shows a data acquisition operation performed in the present embodiment. As described above, the main scanning direction is a circumferential direction centered on the virtual axis 803, but for the sake of description, a two-dimensional drawing in which the circumferential direction is developed into a plane will be described. 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 (the hollow arrow 150A). The wavelength is switched during the movement in the main scanning direction. In this embodiment, the wavelength is switched for each pulse. That is, it switches to λ1, λ2, λ1, λ2,. In order to change the wavelength of the pulse light generated in the laser light source at high speed, two lasers may be used alternately.
By performing such an operation, a photoacoustic signal with respect to the pulse light having the wavelength λ1 and the pulse light having the wavelength λ2 in the partial data acquisition range 110A can be obtained. When the probe 101 rotates 360 degrees around the virtual axis 803, the probe 101 is moved in the sub-scanning direction, and again rotates 360 degrees around the virtual axis 803 (the hollow arrow 150B) to acquire partial data. The data of the range 110B is acquired. Data acquisition is similarly performed for the partial data acquisition ranges 110C and 110D.
During the movement in the main scanning direction as described above, control is performed to switch the wavelength of the pulse light generated from the laser light source unit, and data in a data acquisition range is acquired.

  FIG. 13 is a time chart of the irradiation wavelength in the present embodiment. The range of 160A schematically represents the period during which the wavelength switching is performed for each pulse, and the photoacoustic signals for the pulse light of wavelength λ1 and the pulse light of wavelength 2 in the partial data acquisition range 110A are obtained. . Also, the ranges of 160B, 160C, and 160D correspond to the partial data acquisition ranges 110B, 110C, and 110D, respectively.

  In the probe scanning according to the present 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 the acquisition interval is significantly reduced as compared with the case where the photoacoustic signal for the pulse light irradiation of the wavelength λ2 is acquired after acquiring the photoacoustic signal for the pulse light irradiation of the wavelength λ1 in the entire data acquisition range. .

According to the present embodiment, the wavelength switching is performed during the movement in the main scanning direction, so that the acquisition interval of the photoacoustic signals for different wavelengths in the same partial data acquisition range can be further reduced. That is, it is possible to further suppress an error due to the movement of the subject over time.
Therefore, when data reconstructed from the photoacoustic signals acquired at a plurality of wavelengths (λ1, λ2) is used, and when the oxygen saturation and the like are calculated in the multi-wavelength synthesizing unit, the error due to the displacement is further suppressed, It is possible to construct a highly reliable and highly accurate image.

In this embodiment, the wavelength is switched and the photoacoustic signal is obtained while the probe is continuously moved 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 the wavelength λ1 is irradiated does not exactly coincide with the acquisition position when the light of the wavelength λ2 is irradiated. . However, if the frequency of the pulsed light is sufficiently high, it is possible to proceed with the processing assuming that there is almost no displacement of the acquisition position. Further, even if the photoacoustic signal acquisition positions corresponding to the individual pulse lights are shifted, the reconstruction block 206 calculates the image data of a certain area within the partial data acquisition range. It can be performed.
Alternatively, the probe may be temporarily stopped at a position on the subject, receive a photoacoustic signal using light of wavelengths λ1 and λ2, and then moved to the next position. In this case, it is possible to acquire a photoacoustic signal with almost no time lag at the same receiving position with respect to the subject.

  Further, 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.

  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: reconstruction block, 207: reconstruction data holding unit, 208: multi-wavelength synthesis unit, 210: laser wavelength control unit, 211: scanning control unit

Claims (20)

A light irradiator for irradiating pulsed light of a plurality of wavelengths,
A system control unit that outputs information on a data acquisition region including a plurality of divided regions, which is a target for acquiring subject information, and a timing control signal that controls timing of irradiation of the pulse light,
A wavelength control unit that switches the wavelength of the pulse light based on the timing control signal ,
A probe that receives an acoustic wave generated and propagated in the subject irradiated with the pulse light,
Wherein by changing the based on the data acquired space information about the probe and the relative position between the subject, the scan controller for scanning the pre Symbol the probe to the subject,
At each reception position in the data acquisition area scanned by the probe, output from the probe, the plurality of wavelengths based on each of the plurality of electrical signals corresponding to the plurality of wavelengths of pulsed light. An information processing unit for obtaining subject information;
Has,
The wavelength control unit is configured to scan the inside of the divided region by the probe, or, during the period in which the probe moves between the plurality of divided regions, the wavelength of the pulsed light to irradiate the subject. A subject information acquisition apparatus characterized in that the object information acquisition apparatus switches between the two . The scanning control unit,
In the period during which the probe scans the divided area, the probe is moved in a main scanning direction , which is a direction in which the probe moves while receiving an acoustic wave at each reception position,
The object according to claim 1 , wherein the probe is moved in a sub-scanning direction that intersects the main scanning direction during the period in which the probe moves between the plurality of divided regions. Information acquisition device. The data acquisition area is divided into the plurality of divided regions in the sub-scanning direction,
The wavelength control unit, after the probe has received the acoustic wave corresponding to the pulse light having the first wavelength by the receiving position of the at least one divided region among the plurality of divided areas, in other divided areas 3. The subject information acquiring apparatus according to claim 2, wherein the wavelength of the pulse light is switched to a second wavelength different from the first wavelength before receiving the acoustic wave. The divided region 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 data acquisition region ,
The subject information acquiring apparatus according to claim 3, wherein the wavelength control unit switches the wavelength of the pulse light while the probe is moving in the main scanning direction in the divided area. The subject information acquiring apparatus according to claim 4, wherein the wavelength control unit switches the pulse light of the first wavelength and the pulse light of the second wavelength for each pulse. Wherein the information processing unit acquires the object information using an acoustic wave generated by the irradiation of light of different second wavelength light and the first wavelength of the first wavelength, the object information The subject information acquiring apparatus according to claim 1, wherein the subject information is stored for each wavelength. The subject information acquiring apparatus according to claim 6, wherein the subject information is at least one of an initial sound pressure distribution of the acoustic wave, a light absorption coefficient distribution, and an oxygen saturation.   The subject information acquiring apparatus according to any one of claims 1 to 7, wherein the information processing unit obtains the subject information by a back projection method.   The subject information acquiring apparatus according to any one of claims 1 to 8, wherein the scanning control unit causes the probe to receive the acoustic wave while moving the probe. The apparatus according to claim 9, wherein the scanning control unit moves the probe at a constant speed. An area acquisition step of acquiring information on a data acquisition area that is a target for acquiring subject information and includes a plurality of divided areas,
In the data acquisition area, a light irradiation step of irradiating the subject with pulsed light of a plurality of wavelengths,
A receiving step of receiving an acoustic wave generated and propagated in the subject irradiated with the pulsed light by a probe and outputting an electric signal ,
In the data acquisition area, by changing the relative position between said probe and said object, a scanning step of scanning the pre-Symbol the probe to the subject,
Te each receiving location odor of the data acquisition region wherein probe scans, seeking the object information on the plurality of wavelengths based on each of a plurality of said electrical signals corresponding to the pulsed light of said plurality of wavelengths Information processing step;
Including
In the light irradiating step, during a period in which the probe scans the inside of the divided region, or a period in which the probe moves between the plurality of divided regions, based on the change in the relative position, A method for acquiring object information, comprising: switching a wavelength of the pulse light to be applied to the object. In the scanning step,
In the period during which the probe scans the divided area, the probe is moved in a main scanning direction , which is a direction in which the probe moves while receiving an acoustic wave at each reception position,
In the period in which the probe between the plurality of divided regions is moved, the probe, Before moving to the sub-scanning direction intersecting the main scanning direction
Subject information obtaining method according to claim 11, wherein the this. The data acquisition area is divided into the plurality of divided regions in the sub-scanning direction,
In the light irradiation step, after the probe has received the acoustic wave corresponding to the pulse light having the first wavelength by the receiving position of the at least one divided region among the plurality of divided areas, in other divided areas 13. The subject information acquiring method according to claim 12, wherein a wavelength of the pulse light is switched to a second wavelength different from the first wavelength before receiving the acoustic wave. The divided region 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 data acquisition region ,
14. The object information acquiring method according to claim 13, wherein in the light irradiation step, the wavelength of the pulse light is switched while the probe is moving in the main scanning direction in the divided area. 15. The subject information acquiring method according to claim 14, wherein in the light irradiation step, the pulse light of the first wavelength and the pulse light of the second wavelength are switched for each pulse. Wherein the information processing step obtains the object information by using the acoustic wave generated by the irradiation of light of different second wavelength light and the first wavelength of the first wavelength, the object information 16. The subject information acquiring method according to claim 11, wherein the information is stored for each wavelength. 17. The method according to claim 16, wherein the object information is at least one of an initial sound pressure distribution of the acoustic wave, a light absorption coefficient distribution, and an oxygen saturation.   18. The subject information acquiring method according to claim 11, wherein in the information processing step, the subject information is obtained by a back projection method.   19. The object information acquiring method according to claim 11, wherein, in the scanning step, the probe receives the acoustic wave while moving the probe. 20. The method according to claim 19, wherein, in the scanning step, the probe is moved at a constant speed.

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