JP5681141B2 - Tomographic image generating apparatus, method, and program - Google Patents

Description

  The present invention relates to a tomographic image generation apparatus and method, and more particularly to a tomographic image generation apparatus and method for generating an ultrasonic image based on reflected ultrasonic waves and a photoacoustic image based on photoacoustic signals.

  An ultrasonic inspection method is known as a kind of image inspection method capable of non-invasively examining the state inside a living body. In the ultrasonic inspection, an ultrasonic probe capable of transmitting and receiving ultrasonic waves is used. When ultrasonic waves are transmitted from the ultrasonic probe to the subject (living body), the ultrasonic waves travel inside the living body and are reflected at the tissue interface. By receiving the reflected sound wave with the ultrasonic probe and calculating the distance based on the time until the reflected ultrasonic wave returns to the ultrasonic probe, the internal state can be imaged.

  In addition, photoacoustic imaging is known in which the inside of a living body is imaged using a photoacoustic effect. In general, in photoacoustic imaging, a living body is irradiated with pulsed laser light. Inside the living body, the living tissue absorbs the energy of the pulsed laser light, and ultrasonic waves (photoacoustic signals) are generated by adiabatic expansion due to the energy. By detecting this photoacoustic signal with an ultrasonic probe or the like and constructing a photoacoustic image based on the detection signal, in-vivo visualization based on the photoacoustic signal is possible.

  An apparatus capable of generating a photoacoustic image and an ultrasonic image is described in Patent Document 1, for example. In Patent Document 1, an ultrasonic probe includes a first array element that can transmit and receive ultrasonic waves, and a second array element that can receive photoacoustic waves. The first array element includes a plurality of electromechanical transducer elements arranged in a direction perpendicular to the moving direction (scanning direction) of the ultrasonic probe when scanning by moving the ultrasonic probe. The array element has a plurality of electromechanical transducer elements arranged in two dimensions. The first array element and the second array element are arranged on the same plane and aligned in the scanning direction. In Patent Document 1, the width of the first array element is wider than the width of the second array element, and the ultrasonic image and the photoacoustic image are generated in the same range.

2010-22816 gazette

  By the way, when using the laser for photoacoustics, it is preferable that the irradiation range of the laser beam can be suppressed as much as possible in consideration of damage to the fiber and reduction in power saving. However, since a photoacoustic signal is generated by laser light irradiation, if the laser light irradiation range is narrow, the range that can be imaged by a photoacoustic image is narrowed. Whether or not the desired observation target (region of interest) is imaged in the photoacoustic image cannot be known unless a photoacoustic image is generated. If the desired observation target is not within the imaging range, an ultrasonic search is performed. While moving the touch element, it was necessary to repeatedly irradiate the laser beam and generate the photoacoustic image until the observation target entered the light irradiation range.

  In view of the above, it is an object of the present invention to provide a tomographic image generation apparatus, method, and program capable of suppressing unnecessary laser emission when generating a photoacoustic image within a certain predetermined range.

  In order to achieve the above object, the present invention provides a light source unit, a light irradiation unit for irradiating light emitted from the light source unit toward a subject in a predetermined light irradiation range, and an acoustic wave for the subject. Acoustic wave transmitting means for transmitting, photoacoustic wave generated in the subject by light irradiation, and acoustic wave detecting means for detecting reflected acoustic wave with respect to the transmitted acoustic wave, and reflection detected by the acoustic wave detecting means Based on the acoustic wave, a reflected acoustic wave image generation unit that generates a reflected acoustic wave image in a range wider than the light irradiation range, and a photoacoustic image is generated in the reflected acoustic wave generated by the reflected acoustic wave image generation unit. A light irradiation range setting unit for setting a power range, a light irradiation range control unit for controlling the light irradiation unit so that light is emitted from the light irradiation unit toward the range set by the light irradiation range setting unit, and an acoustic The photoacoustic wave detected by the wave detection means Zui and provides a tomographic image generating apparatus according to claim in a range where the light irradiation range setting means has set that a photoacoustic image generating means for generating photoacoustic images.

  In the present invention, the light irradiation range setting unit displays a predetermined light irradiation range irradiated with light from the light irradiation unit on the reflected acoustic wave image generated by the reflected acoustic wave image generation unit. The setting of the range in which the acoustic image should be generated can be prompted. In this case, when the user performs an operation of moving the range in which the photoacoustic image is to be generated, the light irradiation range setting unit may move the position of the light irradiation range to be displayed according to the operation.

  Instead of the above, it is possible to adopt a configuration in which the light irradiation range setting unit sets a range in which a photoacoustic image is to be generated based on the reflected acoustic wave image generated by the reflected acoustic wave image generation unit. In this case, the light irradiation range setting means refers to a table that stores the observation target and the extraction condition from the reflected acoustic wave image of the observation target in association with each other, and based on the extraction condition corresponding to the observation target specified by the user Then, an observation target may be extracted from the reflected acoustic wave image, and a range including the extracted position of the observation target may be set as a range where a photoacoustic image is to be generated.

  The reflected acoustic wave image generation unit generates a reflected acoustic wave image based on the reflected acoustic wave detected by performing sector scanning, and the photoacoustic image generation unit falls within the range set by the light irradiation range setting unit. Thus, the scanning line is scanned to generate a photoacoustic image.

  The light irradiating unit is composed of an output end of an optical fiber that guides light from the light source unit, and the light irradiation range control means controls the light control unit by displacing the output end of the optical fiber. Good.

  In the present invention, the generated photoacoustic image and the reflected acoustic wave image may be displayed side by side or synthesized.

  The detector element of the acoustic wave detection means may also serve as the transmitter element of the acoustic wave transmission means.

  The tomographic image generation apparatus of the present invention further includes a position sensor for detecting the position of the acoustic wave detection means, and a position measurement means for measuring the position of the acoustic wave detection means based on a signal from the position sensor. can do.

  When the above configuration is adopted, at least one of the photoacoustic image generation unit and the ultrasonic image generation unit uses the position of the acoustic wave detection unit at the time of acoustic wave detection measured by the position measurement unit, and the three-dimensional image Data may be generated.

  The light source may be capable of emitting light having a plurality of different wavelengths.

The present invention also includes a step of transmitting an acoustic wave to the subject and detecting a reflected acoustic wave with respect to the transmitted acoustic wave;
Generating a reflected acoustic wave image based on the detected reflected acoustic wave;
In the generated reflected acoustic wave image, setting a range in which a photoacoustic image should be generated in a narrower range than the reflected acoustic wave image;
Irradiating the subject with light toward a set range;
Detecting a photoacoustic wave generated in the subject by light irradiation;
And a step of generating a photoacoustic image in a set range based on the detected photoacoustic wave.

  The present invention further includes a step of generating a reflected acoustic wave image based on a detection result of the reflected acoustic wave with respect to the acoustic wave transmitted into the subject, and the reflected acoustic wave image is generated in the generated reflected acoustic wave image. A step of setting a range in which a photoacoustic image should be generated in a narrower range, a step of controlling light irradiation on the subject so that light is irradiated in the range set on the subject, There is provided a program for causing a computer to execute a step of generating a photoacoustic image in a set range based on a detection result of a photoacoustic signal generated in a subject by irradiation.

  The tomographic image generation apparatus, method, and program of the present invention set a light irradiation range narrower than the image range of the ultrasonic image in the ultrasonic image, and irradiate the set range with laser light to produce a photoacoustic image. Is generated. By using the ultrasound image, the position of the region of interest in the subject can be specified, and the region of interest is photoacoustic by controlling the light irradiation unit so that the region of interest enters the light irradiation range. Can be imaged with images. In the present invention, it is not necessary to repeat the irradiation of the laser beam and the generation of the photoacoustic image while moving the ultrasonic probe until the region of interest enters the light irradiation range, thereby suppressing unnecessary laser emission. Can do.

1 is a block diagram showing a tomographic image generation device according to a first embodiment of the present invention. (A) And (b) is a block diagram which shows the production | generation range of an ultrasonic image, and the production | generation range of a photoacoustic image. The figure which shows the example of a display screen at the time of the setting of a light irradiation range. The timing chart which shows an operation example. The figure which shows the scanning line at the time of photoacoustic image generation. The wave form diagram which shows the phase matching addition of a photoacoustic signal. The flowchart which shows an operation | movement procedure. The block diagram which shows the tomographic image generation apparatus of 2nd Embodiment of this invention.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 shows a tomographic image generation apparatus according to a first embodiment of the present invention. The tomographic image generation apparatus 10 includes a probe 11, a light source (light source unit) 12, a transmission circuit 13, a reception circuit 14, an AD converter 15, an ultrasonic image generation unit 16, a photoacoustic image generation unit 17, an image synthesis unit 18, and an image display. Means 19, light irradiation range setting means 20, fiber position control means 21, fiber position control motor 22, CPU 24, timing control means 25, and operation unit 26 are provided.

  The light source 12 is configured as a laser light source, for example, and emits light to be irradiated on the subject. What is necessary is just to set the wavelength of a laser beam suitably according to an observation target object. The laser light emitted from the light source 12 is guided to the vicinity of the surface of the subject using light guiding means such as an optical fiber 23, for example. The end of the optical fiber 23 constitutes a light irradiating unit that irradiates the subject with laser light, and the guided laser light irradiates the subject within a predetermined light irradiation range from the emission end of the optical fiber 23. Is done. In other words, the laser beam emitted from the emission end of the optical fiber 23 is irradiated to the subject with a predetermined spread. The fiber position control motor 22 displaces the direction of the emission end of the optical fiber 23 to change the emission direction of the laser light.

  The probe (acoustic wave detecting means) 11 outputs (transmits) an acoustic wave (typically, an ultrasonic wave) to the subject, and acoustics for detecting (receiving) the acoustic wave from the subject. Wave detecting means. The detector element of the acoustic wave detecting means may also serve as the transmitter element of the acoustic wave transmitting means. That is, one element may be used for both transmission and reception of acoustic waves. The acoustic wave detecting means and the acoustic wave transmitting means are not necessarily provided in the same probe, and a configuration in which the acoustic wave detecting means and the acoustic wave transmitting means are placed at different positions is possible.

  The probe 11 includes, for example, a plurality of ultrasonic transducers arranged one-dimensionally as a detector element of the acoustic wave detection unit and a transmitter element of the acoustic wave transmission unit. Each ultrasonic transducer detects a photoacoustic wave generated when the measurement object in the subject absorbs the laser light from the light source 12 after the subject is irradiated with the laser beam. Each ultrasonic transducer outputs an ultrasonic wave toward the inside of the subject and detects a reflected ultrasonic wave (reflected acoustic wave) with respect to the transmitted ultrasonic wave. As the probe 11, for example, a sector scanning type ultrasonic probe can be used. The type of the probe 11 is not particularly limited, and the probe 11 may be a transvaginal or transrectal probe, or may be a microconvex type probe used for an ultrasonic endoscope.

  The transmission circuit 13 drives a plurality of ultrasonic transducers of the probe 11 to transmit ultrasonic waves from the probe 11 toward the subject. The receiving circuit 14 receives a detection signal of an acoustic wave (a photoacoustic wave or a reflected acoustic wave) detected by the probe 11. The AD converter 15 samples the acoustic wave detection signal received by the receiving circuit 14 and converts it into a digital signal. The AD converter 15 samples the ultrasonic signal at a predetermined sampling period in synchronization with the AD clock signal, for example.

  The ultrasonic image generation means 16 generates a reflected acoustic wave image (ultrasonic image) based on a reflected acoustic wave detection signal (hereinafter also referred to as a reflected acoustic signal) detected by the probe 11. The photoacoustic image generation means 17 generates a photoacoustic image based on a photoacoustic wave detection signal (hereinafter also referred to as a photoacoustic signal) detected by the probe 11. The ultrasonic image generation unit 16 generates an ultrasonic image in a wider range than the irradiation range of the laser light irradiated from the light irradiation unit when generating the photoacoustic image. The photoacoustic image generation means 17 generates a photoacoustic image in a range corresponding to the irradiation range of the laser light. The range imaged by the photoacoustic image is narrower than the range imaged by the ultrasonic image.

  The ultrasonic image generation unit 16 includes a phase matching unit 161 and an image construction unit 162. The phase matching unit 161 performs phase matching addition of the reflected acoustic signals detected by the plurality of ultrasonic transducers of the probe 11. For example, the phase matching unit 161 adds the reflected acoustic signals from the 64ch ultrasonic transducers of the probe 11 while delaying them by a delay time corresponding to the position of the ultrasonic transducers. By performing the phase matching addition, an image signal for one scanning line is generated. The image construction unit 162 generates an ultrasonic image after performing, for example, detection and logarithmic conversion on the image signal of each line subjected to phase matching addition.

  The photoacoustic image generation unit 17 includes a phase matching unit 171 and an image construction unit 172. The phase matching unit 171 performs phase matching addition of the photoacoustic signals detected by the plurality of ultrasonic transducers of the probe 11. For example, the phase matching unit 171 adds the photoacoustic signals from the ultrasonic transducers for 64 channels included in the probe 11 while delaying them by a delay time corresponding to the position of the ultrasonic transducers. By performing the phase matching addition, an image signal for one scanning line is generated. The image construction unit 172 generates a photoacoustic image after performing, for example, detection and logarithmic conversion on the image signal of each line.

  The image synthesis unit 18 synthesizes the ultrasonic image generated by the ultrasonic image generation unit 16 and the photoacoustic image generated by the photoacoustic image generation unit 17. The image composition unit 18 performs image composition by superimposing a photoacoustic image on an ultrasonic image, for example. The image display means 19 displays the image synthesized by the image synthesis means 18 on a display monitor or the like. Alternatively, the ultrasonic image and the photoacoustic image may be switched and displayed on the image display means 19 without performing image synthesis, or the photoacoustic image and the ultrasonic image may be displayed side by side at the same time.

  The light irradiation range setting unit 20 sets a range in which a photoacoustic image is to be generated in the ultrasonic image generated by the ultrasonic image generation unit 16. For example, the light irradiation range setting unit 20 displays the light irradiation range irradiated with the laser light from the light irradiation unit on the ultrasonic image generated by the ultrasonic image generation unit 16 and generates a photoacoustic image to the user. Encourage the setting of the range to be performed. For example, the user operates a pointing device such as a trackball included in the operation unit 26 to move the light irradiation range (a range where a photoacoustic image is generated). The light irradiation range setting means 20 moves the position of the light irradiation range to be displayed in accordance with a user operation.

  The fiber position control unit 21 is a light irradiation range control unit, and controls the light irradiation unit so that the laser beam is irradiated from the light irradiation unit toward the range set by the light irradiation range setting unit 20. The fiber position control means 21 drives the fiber position control motor 22, for example, to displace the emission end of the optical fiber 23 that is the light irradiation unit, and controls the traveling direction of the laser light emitted from the light irradiation unit.

  A CPU (Central Processing Unit) 24 controls each unit in the tomographic image generation apparatus 10. The timing control means 25 controls the emission timing of the laser light, the timing of transmitting ultrasonic waves from the probe 11 to the subject, the sampling start timing in the AD converter 15, and the like. The ultrasonic image generation unit 16, the photoacoustic image generation unit 17, the image synthesis unit 18, the light irradiation range setting unit 20, the fiber position control unit 21, and the timing control unit 25 are realized by hardware different from the CPU 24. There is no need, and the functions of these means may be realized by the CPU 24 executing processing according to a predetermined program.

  For example, in a frame for generating an ultrasonic image, the timing control unit 25 instructs the transmission circuit to transmit ultrasonic waves, and also instructs the AD converter 15 to start sampling the reflected acoustic signal. Further, after detecting the reflected acoustic signal, the ultrasonic image generating means 16 is instructed to generate an ultrasonic image. On the other hand, in the frame for generating the photoacoustic image, the light source 12 is instructed to irradiate the laser beam, and the AD converter 15 is instructed to start sampling of the photoacoustic signal in accordance with the emission timing of the laser beam. Further, after the photoacoustic signal is detected, the photoacoustic image generation unit 17 is instructed to generate a photoacoustic image.

  2A and 2B show an ultrasonic image generation range and a photoacoustic image generation range. 2A is a front view, and FIG. 2B is a side view. The probe 11 has, for example, 64 ultrasonic transducers CH0 to CH63 arranged one-dimensionally. In the generation of an ultrasonic image, sector scanning is performed by causing each ultrasonic transducer to transmit ultrasonic waves with a time difference. The ultrasonic image generation means 16 generates an ultrasonic image for a range shown as an image range 30 in FIG. 2 based on the reflected acoustic signal detected by performing sector scanning.

  The direction of the tip (outgoing end) of the optical fiber 23 that constitutes the light irradiating portion can be displaced by driving the fiber position control motor 22, and the irradiation range of the laser light can be changed according to the orientation of the emitting end. Can be changed. The range irradiated with the laser light is narrower than the image range 30 of the ultrasonic image as shown as a light irradiation range 31 in FIG. In the present embodiment, it is assumed that the range in which the laser beam is irradiated matches the range in which the photoacoustic image is generated. That is, the light irradiation range 31 represents the image range of the photoacoustic image.

  For example, the user specifies the position of the part to be observed from the photoacoustic image by referring to the displayed ultrasonic image. For example, in FIG. 2, the region 32 of the measurement object that is the region of interest is partly out of the current light irradiation range 31. In such a case, for example, the user operates the trackball of the operation unit 26 to move the light irradiation range 31 so that the region of interest is irradiated with the laser light.

  FIG. 3 shows an example of a display screen when setting the light irradiation range. The user operates a trackball or the like according to the direction in which the light irradiation range is desired to be moved. The light irradiation range setting means 20 drives the fiber position control motor 22 via the fiber position control means 21 according to the user operation, and changes the light irradiation range. Further, the light irradiation range setting means 20 moves the graphic display representing the light irradiation range 31 displayed on the ultrasonic image in correspondence with the movement of the light irradiation range. The user confirms that the region of interest 32 enters the light irradiation range 31 on the display screen, and operates a predetermined key to determine the light irradiation range.

  The light irradiation range setting means 20 notifies the CPU 24 of the spatial position information of the light irradiation range determined by the user. The CPU 24 notifies the photoacoustic image generation means 17 of the spatial position information of the determined light irradiation range, in other words, the spatial position information of the range where the photoacoustic image is to be generated. The photoacoustic image generation means 17 scans a scanning line within the range set by the light irradiation range setting means 20, for example, and generates a photoacoustic image.

  FIG. 4 is a timing chart showing an operation example. The timing control means 25 generates a frame synchronization signal (a) under the control of the CPU 24. The timing control means 25 generates an ultrasonic image or a photoacoustic image in synchronization with the frame synchronization signal (a). The ratio between the frame that generates the ultrasonic image and the frame that generates the photoacoustic image may be arbitrary. The timing control unit 25 instructs the transmission circuit 13 to transmit an ultrasonic wave and instructs the reception circuit 14 to receive a reflected ultrasonic wave in a frame for generating an ultrasonic image. In addition, the AD converter 15 is instructed to start sampling of reflected ultrasonic waves received by the receiving circuit 14. When the AD converter 15 samples the reflected ultrasound for a predetermined period, the reflected ultrasound sampling data is stored in an element data memory (not shown) (b). The ultrasonic image generation unit 16 adds the reflected ultrasonic waves detected by each element of the probe 11 in phase matching and generates an ultrasonic image.

  On the other hand, the timing control means 25 instructs the light source 12 to irradiate laser light at the rising timing of the frame synchronization signal of the frame immediately before the frame for generating the photoacoustic image (c). The light source 12 emits the laser beam after a predetermined time after receiving the laser beam irradiation instruction (d). The timing control means 25 instructs the reception circuit 14 to receive a photoacoustic signal. Further, the AD converter 15 is instructed to start sampling of the photoacoustic signal in accordance with the actual emission timing of the laser light. When the AD converter 15 samples the photoacoustic signal only for a predetermined period, the photoacoustic signal sampling data is stored in an element data memory (not shown) (e). The photoacoustic image generation means 17 phase-match-adds the photoacoustic signals detected by each element of the probe 11 to generate a photoacoustic image.

  FIG. 5 shows scanning lines when generating a photoacoustic image. The probe 11 has, for example, 64 ultrasonic transducers. It is assumed that the rightmost side is CH0 and the leftmost side is CH63. The photoacoustic image generation means 17 sets, for example, a scanning line passing through the center of 64 ultrasonic transducers within the light irradiation range 31, and adds 64 ch of photoacoustic signals in phase matching for each scanning line.

FIG. 6 shows the phase matching addition of the photoacoustic signal. In the phase matching addition, the time is t, and the delay amount corresponding to the position of the ultrasonic transducer is tdlyi (i is a ch number of 0 to 63).
It can be expressed as In phase matching addition, phase matching addition including electronic steering is performed. In FIG. 5, the scanning line is steered toward the light absorber. In that case, the delay amount (tdly0) on the CH0 side is larger than the delay amount (tdly63) on the CH63 side. Note that phase matching addition in ultrasonic image generation is the same process as phase matching addition in photoacoustic image generation. However, in the photoacoustic image generation, the phase matching addition is performed in consideration of the delay amount for the return path distance (one way), whereas in the ultrasonic image generation, the phase matching addition is performed in consideration of the delay amount of the round trip distance.

  FIG. 7 shows an operation procedure. The transmission circuit 13 drives a plurality of ultrasonic transducers included in the probe 11 to transmit ultrasonic waves from the probe 11 into the subject (step S1). The receiving circuit 14 receives the reflected ultrasonic waves detected by the respective ultrasonic transducers of the probe 11, and the AD converter 15 performs AD conversion on the received reflected ultrasonic waves (step S2). The ultrasonic image generation unit 16 performs phase matching addition on the sampling data of the reflected ultrasonic wave that has been AD converted by the phase matching unit 161 (step S3), and the reflected ultrasonic wave that has been phase-added by the image construction unit 162. An ultrasonic image is generated from (Step S4).

  The light irradiation range setting means 20 superimposes and displays the laser light irradiation range on the ultrasonic image, and prompts the user to set the light irradiation range. The user operates the operation unit 26 while viewing the ultrasonic image, and sets the light irradiation range so that a desired observation target (region of interest) falls within the light irradiation range (step S5). The fiber position control means 21 drives the fiber position control motor 22 and controls the direction of the emission end of the optical fiber 23 that is a light irradiation unit so that the laser light is irradiated to the light irradiation range set by the user ( Step S6). When the user performs an operation to confirm the setting of the light irradiation range, the light irradiation range setting unit 20 notifies the CPU 24 of the spatial information of the light irradiation range (step S7).

  After setting the light irradiation range, the timing control means 25 sends a light emission command to the light source 12 according to an instruction from the CPU 24. When receiving the light emission command, the light source 12 emits a laser beam after a predetermined time has elapsed. The emitted laser light is applied to the subject from the emission end of the optical fiber 23 (step S8). The receiving circuit 14 receives the photoacoustic signal detected by each ultrasonic transducer of the probe 11, and the AD converter 15 performs AD conversion on the received photoacoustic signal (step S9). The photoacoustic image generation means 17 performs phase matching addition on the sampling data of the photoacoustic signal AD-converted by the phase matching means 171 (step S10), and the photoacoustic signal phase-added by the image construction means 172. A photoacoustic image is generated from (step S11).

  In the present embodiment, an ultrasonic image is generated before generating a photoacoustic image, and a light irradiation range narrower than the image range of the ultrasonic image is set in the ultrasonic image. In the generation of the photoacoustic image, laser light is irradiated to the light irradiation range set using the ultrasonic image, and the photoacoustic image is generated within the range. Observe the ultrasound image, confirm the position of the region of interest to be observed with the photoacoustic image, and set the light irradiation range so that the region of interest is included in the light irradiation range. Can be imaged with images. In particular, by displaying the light irradiation range in an overlapping manner on the ultrasonic image and moving the light irradiation range to be displayed in accordance with the user operation, the user can grasp the positional relationship between the light irradiation range and the region of interest while The irradiation range can be adjusted.

  Here, in consideration of extending the image range of the photoacoustic image to a range similar to the image range of the ultrasonic image, in order to detect the photoacoustic signal with sufficient intensity, the laser of the laser light emitted from the light source 12 is used. It is necessary to increase power. Considering damage to the optical fiber 23 and power consumption, it is not preferable to use a high-power laser beam. In the present embodiment, since the light irradiation range is narrower than the image range of the ultrasonic image, it is not necessary to enter high-power laser light into the optical fiber 23, and damage to the optical fiber 23 can be suppressed. Power consumption can be reduced.

  On the other hand, when the light irradiation range is narrowed, the image range of the photoacoustic image is narrowed. If the image range of the photoacoustic image is narrower than the image range of the ultrasonic image, the region of interest that can be observed in the ultrasonic image cannot be observed in the photoacoustic image unless the light irradiation range is set appropriately. In this embodiment, since the light irradiation range is set using the ultrasonic image, the region of interest can be obtained without repeatedly performing laser light irradiation and photoacoustic image generation while moving the ultrasonic probe. Can be irradiated with laser light. In the present embodiment, since the region of interest can be easily irradiated with laser light, unnecessary laser emission when the region of interest is imaged with a photoacoustic image can be suppressed.

  In the above-described embodiment, the light irradiation range setting unit 20 has been described as setting the light irradiation range in accordance with a user operation. Instead, the light irradiation range setting unit 20 includes an ultrasonic image or an image thereof. A light irradiation range (a range in which a photoacoustic image is to be generated) may be set based on the reflected ultrasound of the generation source. For example, the light irradiation range setting unit 20 may extract a region of interest based on the pixel value (luminance value) of the ultrasound image, and set a range including the extracted position of the region of interest as the light irradiation range. Instead of or in addition to this, the light irradiation range setting means 20 may detect a Doppler component from the reflected ultrasonic wave and set a range including a region where a large Doppler component is detected as the light irradiation range. The user can set (select) how the light irradiation range setting means 20 sets the light irradiation range based on the ultrasonic image.

  When extracting the region of interest from the ultrasonic image, the light irradiation range setting unit 20 may use a table that stores the observation target and the extraction condition from the ultrasonic image of the observation target in association with each other. For example, for the observation target “cyst”, “low echo part in medium luminance tissue part” is registered in the table as an extraction condition, and for the observation target “tumor”, “high echo part in medium luminance tissue part” "Is registered in the table as an extraction condition. When the user designates the observation target, the light irradiation range setting unit 20 reads out the extraction condition corresponding to the designated observation target from the table, and extracts the observation target from the ultrasonic image according to the read out extraction condition. For example, when the user designates “cyst” as an observation target, the corresponding extraction condition “low echo part in medium luminance tissue part” is read, and the “cyst” part is extracted from the ultrasound image according to the extraction condition . The user may arbitrarily adjust the light irradiation range with respect to the light irradiation range automatically set by the light irradiation range setting means 20.

  FIG. 8 shows a tomographic image generation apparatus according to the second embodiment of the present invention. The tomographic image generation apparatus 10a of the present embodiment further includes a position sensor 27 and a position measurement unit 28 in addition to the configuration of the tomographic image generation apparatus 10 of the first embodiment shown in FIG. The position sensor 27 is a sensor for detecting the position of the probe 11. A magnetic sensor can be used as the position sensor 27. The position measuring unit 28 measures the position of the probe 11 when detecting an acoustic wave (photoacoustic wave or reflected acoustic wave) based on a signal from the position sensor 27.

  The probe 11 includes an acoustic wave detection unit 11a and an acoustic wave transmission unit 11b. For the acoustic wave detection means 11a, an element such as PVDF (polyvinylidene fluoride) having a wide reception band for photoacoustics is used. On the other hand, an element such as PZT (lead zirconate titanate) is used for the acoustic wave transmitting means 11b. For example, when the acoustic wave detection unit 11a and the acoustic wave transmission unit 11b are separated, the position sensor 27 may be attached to the acoustic wave detection unit 11a.

  In the present embodiment, at least one of the ultrasonic image generation unit 16 and the photoacoustic image generation unit 27 uses a position information of the acoustic wave detection unit 11a at the time of acoustic wave detection measured by the position measurement unit 28 to obtain a three-dimensional image. Data (volume data) can be generated. For example, the position information measured by the position measuring unit 28 is input to the CPU 24. The CPU 24 causes the ultrasonic image generating unit 16 and the photoacoustic image generating unit 17 to detect a plurality of ultrasonic images and photoacoustic images at the time of acoustic wave detection. The acoustic wave detection means 11a is controlled to be coupled according to the position. By doing in this way, the three-dimensional image data of a photoacoustic image and an ultrasonic image can be produced | generated. The ultrasonic image generation unit 16 and the photoacoustic image generation unit 17 may generate three-dimensional image data in real time in synchronization with the scanning of the probe 11. Alternatively, the three-dimensional image data may be generated after the detection target space has been scanned.

  In the present embodiment, the light source 12 is configured to be able to emit laser beams having a plurality of different wavelengths. The operation unit 26 is provided with a wavelength selection switch for receiving, for example, a wavelength selection operation. For example, the user can select the wavelength of the laser beam irradiated on the subject from a plurality of wavelengths that can be emitted by the light source 12 by operating a wavelength selection switch provided in the operation unit 26. The user selects a laser wavelength according to, for example, the observation target region and the type of functional image desired to be used. When irradiating a subject with light of a plurality of wavelengths, the light irradiation range setting unit 20 may set a light irradiation range for each wavelength.

  In the present embodiment, a position sensor 27 is provided, and the position measuring means 28 measures the position of the probe 11. By measuring the position of the probe 11 at the time of acoustic wave detection, the ultrasonic image and photoacoustic image generated based on the detected acoustic wave can be associated with the position in the subject. By using such position information, three-dimensional image data of an ultrasonic image and a photoacoustic image can be constructed. Further, in the present embodiment, the light source 12 is configured to be able to emit light of a plurality of wavelengths, and the user can select an arbitrary wavelength and perform light irradiation on the subject.

  Although the present invention has been described based on the preferred embodiment, the tomographic image generation apparatus, method, and program according to the present invention are not limited to the above embodiment, and various configurations are possible from the configuration of the above embodiment. Those modified and changed as described above are also included in the scope of the present invention.

10: tomographic image generation device 11: probe 12: light source 13: transmission circuit 14: reception circuit 15: AD converter 16: ultrasonic image generation means 17: photoacoustic image generation means 18: image composition means 19: image display means 20: Light irradiation range setting means 21: fiber position control means 22: fiber position control motor 23: optical fiber 24: CPU
25: Timing control means 26: Operation unit 27: Position sensor 28: Position measurement means 30: Image range 31 of ultrasonic image 31: Light irradiation range (image range of photoacoustic image)
32: Region of interest 161, 171: Phase matching means 162, 172: Image construction means

Claims (14)

A light source unit;
A light irradiation unit that emits light emitted from the light source unit toward a subject in a predetermined light irradiation range;
An acoustic wave transmitting means for transmitting an acoustic wave to the subject;
An acoustic wave detecting means for detecting a photoacoustic wave generated in the subject by the irradiation of light and a reflected acoustic wave with respect to the transmitted acoustic wave;
Based on the reflected acoustic wave detected by the acoustic wave detecting means, a reflected acoustic wave image generating means for generating a reflected acoustic wave image in a range wider than the light irradiation range;
In the reflected acoustic wave generated by the reflected acoustic wave image generating means, a light irradiation range setting means for setting a range in which a photoacoustic image is to be generated;
A light irradiation range control means for controlling the light irradiation section so that light is emitted from the light irradiation section toward the range set by the light irradiation range setting means;
A tomographic image generation apparatus comprising: a photoacoustic image generation unit configured to generate a photoacoustic image within a range set by the light irradiation range setting unit based on a photoacoustic wave detected by the acoustic wave detection unit.   The light irradiation range setting unit displays a predetermined light irradiation range irradiated with light from the light irradiation unit on the reflected acoustic wave image generated by the reflected acoustic wave image generation unit, and displays the light to the user. The tomographic image generation apparatus according to claim 1, which prompts the user to set a range in which an acoustic image is to be generated.   When the user performs an operation of moving the range in which the photoacoustic image is to be generated, the light irradiation range setting unit moves the position of the light irradiation range to be displayed according to the operation. The tomographic image generation apparatus according to claim 2.   The said light irradiation range setting means sets the range which should produce | generate the said photoacoustic image based on the reflected acoustic wave image which the said reflected acoustic wave image generation means produced | generated, The Claim 1 characterized by the above-mentioned. The tomographic image generation device described.   The light irradiation range setting means refers to a table that stores the observation target and the extraction condition from the reflected acoustic wave image of the observation target in association with each other, and based on the extraction condition corresponding to the observation target specified by the user The tomographic image according to claim 4, wherein an observation target is extracted from the reflected acoustic wave image, and a range including the position of the extracted observation target is set as a range in which the photoacoustic image is to be generated. Generator.   The reflected acoustic wave image generation unit generates a reflected acoustic wave image based on the reflected acoustic wave detected by performing sector scanning, and the photoacoustic image generation unit is set by the light irradiation range setting unit. The tomographic image generation device according to claim 1, wherein the photoacoustic image is generated by scanning a scanning line within the range.   The light irradiating unit is configured by an output end of an optical fiber that guides light from the light source unit, and the light irradiation range control unit displaces the output end of the optical fiber to thereby change the light control unit. The tomographic image generation apparatus according to claim 1, wherein the tomographic image generation apparatus according to claim 1 is controlled.   The tomographic image generation apparatus according to claim 1, wherein the generated photoacoustic image and the reflected acoustic wave image are displayed side by side or synthesized.   The tomographic image generation apparatus according to any one of claims 1 to 8, wherein a detector element of the acoustic wave detection unit also serves as a transmitter element of the acoustic wave transmission unit. A position sensor for detecting the position of the acoustic wave detection means;
The tomographic image generation apparatus according to claim 1, further comprising a position measurement unit that measures a position of the acoustic wave detection unit based on a signal from the position sensor.   At least one of the photoacoustic image generation means and the ultrasonic image generation means generates three-dimensional image data using the position of the acoustic wave detection means at the time of acoustic wave detection measured by the position measurement means. The tomographic image generation apparatus according to claim 10.   The tomographic image generation apparatus according to claim 1, wherein the light source is capable of emitting light having a plurality of different wavelengths. Transmitting acoustic waves to the subject and detecting reflected acoustic waves with respect to the transmitted acoustic waves;
Generating a reflected acoustic wave image based on the detected reflected acoustic wave;
In the generated reflected acoustic wave image, setting a range in which a photoacoustic image is to be generated in a narrower range than the reflected acoustic wave image;
Irradiating the subject with light toward the set range;
Detecting a photoacoustic wave generated in the subject by the light irradiation;
A tomographic image generation method comprising: generating a photoacoustic image in the set range based on the detected photoacoustic wave. Generating a reflected acoustic wave image based on the detection result of the reflected acoustic wave with respect to the acoustic wave transmitted into the subject;
In the generated reflected acoustic wave image, setting a range for generating a photoacoustic image in a range narrower than the reflected acoustic wave image;
A step of controlling light irradiation on the subject so that light is irradiated on the subject in the set range; and
A program for causing a computer to execute a step of generating a photoacoustic image in the set range based on a detection result of a photoacoustic signal generated in a subject by the irradiation of light.