JP2012075511A - Photoacoustic diagnostic imaging equipment, image generating method, and program - Google Patents

Abstract

In a photoacoustic image diagnostic apparatus, even when there is a variation in light irradiation timing, a reduction in image quality of a generated photoacoustic image is suppressed.
An ultrasonic image construction means 18 generates an ultrasonic image. The first photoacoustic image construction means 17 generates a photoacoustic image based on the photoacoustic signal generated by the light irradiated on the subject. The deviation amount detection means 19 detects the deviation amount in the time axis direction between the two images based on the photoacoustic image and the ultrasonic image. The second photoacoustic image construction unit 20 generates a photoacoustic image based on the detected deviation.
[Selection] Figure 1

Description

  The present invention relates to a photoacoustic image diagnostic apparatus, an image generation method, and a program. More specifically, the present invention relates to a photoacoustic image diagnostic apparatus that irradiates a living tissue with light and generates an image based on an acoustic signal generated along with the light irradiation. The present invention relates to an image generation method and a program.

  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, the ultrasonic waves travel inside the subject 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 such as a laser pulse. 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. Regarding a photoacoustic image and an ultrasonic image, Patent Document 1 describes that both images are generated at the same position, combined, and displayed.

JP 2010-12295 A

  In general, in a photoacoustic image diagnostic apparatus based on an ultrasonic diagnostic apparatus, a laser emission trigger signal is output from the photoacoustic image diagnostic apparatus to a laser light source, and the laser light source responds to the trigger signal with laser light. Is emitted. The photoacoustic image diagnostic apparatus receives a photoacoustic signal generated by a laser beam output from a laser light source by an ultrasonic probe, and performs imaging by performing image reconstruction on the received photoacoustic signal. .

  Here, the reception start timing of the ultrasonic probe as the reception system is fixedly determined based on the output timing of the trigger signal to the laser light source. That is, the time from the trigger signal output timing to the photoacoustic signal reception start (sampling start) timing in the ultrasonic probe is a fixed time. However, jitter may occur in the time taken from when the laser light source receives the trigger signal to when the laser light is actually emitted, and the laser emission timing may vary. When the laser emission varies, the photoacoustic signal may start to be received with a deviation from the intended reception start point.

  When the reception start point of the photoacoustic signal deviates from the expected timing, the measurement object is displayed deviated from the original position in the photoacoustic image. For example, if the light irradiation timing is earlier than the expected timing, the ultrasonic probe receives the photoacoustic signal earlier by the timing difference, and the measurement object is displayed at a shallow position as a whole position in the photoacoustic image. Will be. In addition, when adding signals of a plurality of channels using, for example, a delay addition method, the signals are added with a delay time based on an incorrect position, resulting in a blurred image or artifacts. May occur.

  In order to solve the above problem, it is necessary to offset the received data of the photoacoustic signal to the laser light source in accordance with the jitter each time. However, since there is no absolute reference, it is difficult to determine the offset amount appropriately. The technique described in Patent Document 1 is merely a method of combining and displaying a photoacoustic image and an ultrasonic image, and does not solve the above-described problem in the photoacoustic image.

  In view of the above, the present invention provides a photoacoustic image diagnostic apparatus, an image generation method, and a program that can suppress a decrease in image quality of a generated photoacoustic image even when the light irradiation timing varies. Objective.

  In order to achieve the above object, the present invention provides an ultrasonic image constructing unit that generates an ultrasonic image and a photoacoustic image that generates a photoacoustic image based on a photoacoustic signal generated by light irradiated in a subject. An image construction means; and a deviation amount detection means for detecting a deviation amount in the time axis direction between the two images based on the ultrasonic image and the photoacoustic image, wherein the photoacoustic image construction means comprises the detection Provided is a photoacoustic image diagnostic apparatus characterized in that the photoacoustic image is regenerated based on the shifted deviation.

  The photoacoustic image construction means corrects the time axis of the photoacoustic signal by the amount of deviation in the time axis direction detected by the deviation amount detection means, and regenerates the photoacoustic signal. it can.

  The photoacoustic image diagnostic apparatus can be configured to repeatedly perform the regeneration of the photoacoustic image and the detection of the deviation until the deviation detected by the deviation amount detection unit becomes a predetermined threshold value or less. .

  A configuration may be adopted in which the deviation amount detecting means obtains a correlation between the ultrasonic image and the photoacoustic image and detects the deviation amount based on the obtained correlation.

  Instead of the above, the photoacoustic image diagnostic apparatus further includes a feature point extraction unit that extracts a predetermined feature point from the ultrasonic image to generate a feature point image, and the shift amount detection unit includes the feature point image. It is good also as a structure which calculates | requires the correlation with the said photoacoustic image, and detects the said deviation | shift amount based on this calculated | required correlation. In this case, the feature point extraction unit may extract a feature point corresponding to a blood vessel portion from the ultrasound image, and generate a blood vessel image including the extracted blood vessel portion as the feature point image.

  The deviation amount detection means detects a deviation amount between a comparison point set for the ultrasonic image and a comparison point set for the photoacoustic image and corresponding to a comparison point in the ultrasonic image. May be.

  The present invention also includes a step of generating an ultrasonic image based on a reflected acoustic signal with respect to the ultrasonic wave output in the subject, a photoacoustic signal generated by the light irradiated in the subject, A step of generating a photoacoustic image based on the acquired photoacoustic signal, a step of detecting a shift amount in the time axis direction between the two images based on the ultrasonic image and the photoacoustic image, and the detection And a step of regenerating the photoacoustic image based on misalignment. A photoacoustic image generation method is provided.

  Furthermore, the present invention acquires, in a computer, a procedure for generating an ultrasonic image based on a reflected acoustic signal with respect to an ultrasonic wave output in the subject, and a photoacoustic signal generated by light irradiated in the subject. A procedure for generating a photoacoustic image based on the acquired photoacoustic signal, a procedure for detecting a shift amount in the time axis direction between the images based on the ultrasonic image and the photoacoustic image, A program for executing a procedure for regenerating the photoacoustic image based on the detected deviation is provided.

  In the photoacoustic image diagnostic apparatus of the present invention, the amount of deviation between the photoacoustic image and the ultrasonic image is obtained, and the photoacoustic image is constructed again using the obtained amount of deviation. By doing so, it is possible to correct the positional deviation in the depth direction of the photoacoustic generation source even when there is a variation in the time from the output of the light irradiation trigger to the actual light irradiation. By reconstructing the photoacoustic image in a state where the position of the photoacoustic generation source is corrected, it is possible to suppress deterioration in the image quality of the photoacoustic image.

The block diagram which shows the photoacoustic image diagnostic apparatus of 1st Embodiment of this invention. The figure which shows the image structure by a delay addition method. The figure which shows the image structure by CBP method. The flowchart which shows an operation | movement procedure. The figure which shows the relationship between the elapsed time from the start of sampling, and delay time. The figure which shows the example in which delay addition is not performed correctly. The figure which illustrates an ultrasonic image. The figure which illustrates the photoacoustic image produced | generated provisionally. The figure which illustrates the regenerated photoacoustic image. The block diagram which shows the photoacoustic image diagnostic 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 photoacoustic image diagnostic apparatus according to a first embodiment of the present invention. The photoacoustic image diagnostic apparatus 10 includes an ultrasonic probe 11, an AD conversion unit 12, a trigger control unit 13, a laser light source 14, a signal processing unit 15, and an image display unit 22. The photoacoustic image diagnostic apparatus 10 can generate both an ultrasonic image and a photoacoustic image. The laser light source 14 irradiates a subject with laser light when generating a photoacoustic image. What is necessary is just to set the wavelength of a laser beam suitably according to an observation target object.

  The ultrasonic probe 11 detects an ultrasonic signal output from the subject and an acoustic signal from the subject. The ultrasonic probe 11 has, for example, a plurality of ultrasonic transducers (elements) arranged one-dimensionally. For example, when generating an ultrasonic image, the ultrasonic probe 11 outputs ultrasonic waves from a plurality of ultrasonic transducers and detects reflected ultrasonic waves (hereinafter also referred to as reflected acoustic signals) with respect to the output ultrasonic waves. . When generating a photoacoustic image, the ultrasonic probe 11 detects an ultrasonic wave (hereinafter also referred to as a photoacoustic signal) generated when a measurement object in the subject absorbs laser light from the laser light source 14. To do.

  The AD conversion means 12 converts the ultrasonic waves detected by a plurality of ultrasonic transducers included in the ultrasonic probe 11 into digital signals. The AD conversion unit 12 samples the detected ultrasonic wave at a predetermined sampling period, for example. The trigger control means 13 controls the irradiation timing of the laser light from the laser light source 14 into the subject. The trigger control means 13 controls the output timing of ultrasonic waves from the ultrasonic probe 11 into the subject. Further, the trigger control unit 13 controls the timing of starting sampling of the ultrasonic wave (photoacoustic signal or reflected acoustic signal) by the AD conversion unit 12.

  The trigger control means 13 outputs a trigger signal (photoacoustic trigger) to the laser light source 14 when generating a photoacoustic image. The laser light source 14 outputs laser light in the subject in response to the photoacoustic trigger. The AD converter 12 starts sampling of the photoacoustic signal at a timing that has a predetermined time relationship with the timing of the photoacoustic trigger. The trigger control means 13 outputs a trigger signal (ultrasonic transmission trigger) to the ultrasonic probe 11 when generating an ultrasonic image. The ultrasonic probe 11 outputs an ultrasonic wave in the subject in response to the ultrasonic transmission trigger. The AD converter 12 starts sampling the reflected acoustic signal at a timing that is in a predetermined time relationship with the timing of the ultrasonic transmission trigger.

  The signal processing unit 15 includes a mode switching unit 16, a first photoacoustic image construction unit 17, an ultrasonic image construction unit 18, a deviation amount detection unit 19, a second photoacoustic image construction unit 20, and an image selection unit 21. Prepare. The signal processing unit 15 generates a photoacoustic image and an ultrasonic image based on the photoacoustic signal and the reflected acoustic signal converted into digital signals by the AD conversion unit 12. The function of each part in the signal processing means 15 can be realized by a computer executing processing according to a predetermined program.

  The mode switching unit 16 switches between the photoacoustic image generation mode and the ultrasonic image generation mode. The mode switching unit 16 inputs the sampling result of the photoacoustic signal output from the AD conversion unit 12 to the first photoacoustic image construction unit 17 in the photoacoustic image generation mode. In the ultrasonic image generation mode, the mode switching unit 16 inputs the reflected acoustic signal sampling result output from the AD conversion unit 12 to the ultrasonic image construction unit 18.

  The first photoacoustic image construction unit 17 generates a photoacoustic image based on the input photoacoustic signal. The ultrasonic image construction unit 18 generates an ultrasonic image based on the reflected acoustic signal. The deviation amount detection means 19 detects the deviation amount in the time axis direction between the two images based on the ultrasonic image and the photoacoustic image. Here, the shift in the time axis direction between images corresponds to a shift in the position in the depth direction in the image. The deviation amount detection means 19 obtains, for example, the correlation between the ultrasonic image and the photoacoustic image, and detects the deviation amount in the time axis direction between the images based on the obtained correlation.

  The second photoacoustic image construction means 20 regenerates the photoacoustic image based on the deviation detected by the deviation amount detection means 19. The image generation technique in the first photoacoustic image construction means 17 and the image generation technique in the second photoacoustic image construction means 20 may be the same technique. In FIG. 1, for the sake of convenience, the first photoacoustic image construction unit 17 and the second photoacoustic image construction unit 20 are separate units, but the generation and detection of a photoacoustic image based on a photoacoustic signal are detected. You may perform both the regeneration of the photoacoustic image which correct | amended only the shift | offset | difference with one photoacoustic image construction means.

  The image selection means 21 outputs at least the photoacoustic image generated by the second photoacoustic image construction means 20. The image selection means 21 selectively outputs, for example, a photoacoustic image and an ultrasonic image. Or you may synthesize | combine and output a photoacoustic image and an ultrasonic image. The image display means 22 is a device such as a display monitor, for example, and displays the image output from the image selection means 21 on the display screen. The image display means 22 displays a photoacoustic image and an ultrasonic image side by side, for example. Or the image display means 22 may switch and display a photoacoustic image and an ultrasonic image, and may superimpose and display a photoacoustic image and an ultrasonic image.

  A delay addition method can be used to generate the photoacoustic image. FIG. 2 shows an image configuration by the delay addition method. In FIG. 2, the vertical position z corresponds to the elapsed time from the start of photoacoustic signal sampling. In the delay addition method, the observation element data having the same time for the spherical wave generated from the sound source at the point (x, z) in space to reach the element surface of the ultrasonic probe 11 is added to depict the sound source. For example, in FIG. 2, when data having a black circle as a sound source is drawn, data of white circles having the same time for the photoacoustic signal from the sound source to reach each element is added.

  Instead of the above, a CBP (Circular Back Projection) method may be used for generating a photoacoustic image. FIG. 3 shows an image configuration by the CBP method. In the CBP method, with respect to the data of each element of the ultrasound probe 11, assuming that there are sound source candidate points within a circle centered on each element, spatially adding them as circles, The most likely point is drawn. For example, if the point immediately below the leftmost element in the drawing is the measurement point (xr, tr), a circle is drawn assuming that there is a sound source somewhere on the circle of radius c × tr. By performing this for all element data, a sound source can be drawn.

  FIG. 4 shows an operation procedure. The trigger control means 13 outputs an ultrasonic transmission trigger to the ultrasonic probe 11 (step S1). The ultrasonic probe 11 outputs an ultrasonic wave in the subject and detects a reflected acoustic signal reflected in the subject. The AD conversion means 12 starts sampling of the reflected acoustic signal at a timing based on the ultrasonic transmission trigger, and acquires reflected acoustic data (step S2). The mode switching unit 16 inputs the acquired reflected acoustic data to the ultrasonic image construction unit 18. The ultrasonic image construction unit 18 generates an ultrasonic image based on the reflected acoustic data (step S3). Any generation method can be used to generate the ultrasonic image.

  Subsequently, the trigger control means 13 outputs a photoacoustic trigger to the laser light source 14 (step S4). In response to the photoacoustic trigger, the laser light source 14 irradiates, for example, pulse laser light into the subject. The ultrasonic probe 11 detects a photoacoustic signal generated by the light irradiated into the subject. The AD conversion means 12 starts photoacoustic signal sampling at a timing based on the photoacoustic trigger, and acquires photoacoustic data (step S5). The mode switching unit 16 inputs the acquired photoacoustic data to the first photoacoustic image construction unit 17. The 1st photoacoustic image construction means 17 produces | generates a photoacoustic image based on photoacoustic data (step S6).

  In the above description, reflected acoustic data is first acquired to generate an ultrasonic image, and then photoacoustic data is acquired to generate a photoacoustic image. Either can be acquired first. In addition, the acquired reflected acoustic data and photoacoustic data are temporarily stored in an element data memory (not shown), and information necessary for generating an ultrasonic image and a photoacoustic image is stored in the element data memory. A sound wave image and a photoacoustic image may be generated.

  The deviation amount detection means 19 inputs the ultrasonic image generated in step S3 and the photoacoustic image generated in step S6. The deviation amount detection means 19 detects the deviation amount of the position in the time axis direction between the ultrasonic image and the photoacoustic image (step S7). The shift amount detection means 19 obtains a correlation (similarity) between the images at each shifted position while relatively shifting the positions of the ultrasonic image and the photoacoustic image, for example. The shift amount detection means 19 detects the shift amount that maximizes the correlation between the two images as the shift amount between the images.

  The deviation amount detection means 19 outputs the detected deviation amount to the second photoacoustic image construction means 20. The second photoacoustic image construction unit 20 generates a photoacoustic image from the photoacoustic data that the first photoacoustic image construction unit 17 has generated the photoacoustic image, based on the input shift amount (step). S8). The second photoacoustic image construction means 20 generates a photoacoustic image by correcting the time axis in the photoacoustic data, for example, by the amount of deviation detected by the deviation amount detection means 19.

  The image selection unit 21 outputs, for example, a photoacoustic image or an ultrasonic image to the image display unit 22 according to a user operation (step S9). The photoacoustic image output in step S9 is not the photoacoustic image generated by the first photoacoustic image construction unit 17, but the photoacoustic image generated by the second photoacoustic image construction unit 20. The image display means 22 displays, for example, a photoacoustic image and an ultrasonic image side by side or by switching.

  Here, the time taken from the output of the photoacoustic trigger until the laser light source 14 actually irradiates the subject with the laser light varies, and the light generated by the first photoacoustic image construction means 17 in step S7. The acoustic image may be generated in a state where the position in the depth direction of the measurement object is shifted from the intended position (original position). When the position of the measurement object in the depth direction is deviated from the original position, the photoacoustic image is blurred when the photoacoustic image is generated from the photoacoustic data by the delay addition method (FIG. 2), for example. Sometimes. This will be described below.

  FIG. 5 shows the relationship between the elapsed time from the start of sampling and the delay time. In the generation of the photoacoustic image, for example, data for one line is generated by delay-adding 32 element data. In FIG. 5, the vertical axis represents the elapsed time from the start of sampling in the AD conversion means 12. This corresponds to the position of the sound source in the depth direction. The horizontal axis corresponds to the position of the element of the ultrasonic probe 11 that is added when data for one line is generated. FIG. 5 shows a curve representing a delay time when generating image data at each elapsed time position in increments of 100 μs from an elapsed time of 100 μs. For example, when generating image data at a position corresponding to 300 μs in a photoacoustic image, element data at a time delayed from 300 μs by a delay time represented by the difference between the curve with a black circle in FIG. 5 and 300 μs ( 32ch) is added.

  FIG. 6 shows an example in which delay addition is not performed correctly. For example, it is assumed that the irradiation timing of laser light is advanced by 100 μs from the expected timing. By advancing the laser irradiation timing, for example, a photoacoustic signal from a sound source existing at a point with an elapsed time of 300 μs is received as a photoacoustic signal from a point with an elapsed time of 200 μs. In FIG. 6, the line representing the delay time at the position corresponding to the elapsed time of 300 μs is shifted to the position of 200 μs and indicated by a broken line. Originally, element data of each element should be delayed and added with a delay time determined based on a curve (broken line) corresponding to the elapsed time of 300 μs with a black circle in FIG. 6, which corresponds to an elapsed time of 200 μs with a white square. By delay-adding the element data of each element with a delay time determined based on the curve, image generation cannot be performed correctly, and the image becomes a totally blurred image.

  On the other hand, considering the ultrasonic image, the ultrasonic probe 11 actually outputs ultrasonic waves into the subject after the trigger control means 13 outputs an ultrasonic transmission trigger to the ultrasonic probe 11. It is considered that the time required until the time is constant. Therefore, in the ultrasonic image, the problem of displacement due to the above-described variation does not occur. Therefore, in the present embodiment, the deviation between the reference image and the photoacoustic image is obtained by the deviation amount detection means 19 using the ultrasonic image as the reference image. That is, the first photoacoustic image construction means 17 tentatively generates a photoacoustic image assuming that there is no variation in the light irradiation timing, and the deviation amount detection means 19 generates the tentatively generated photoacoustic image and ultrasonic waves. The amount of deviation between images is obtained by comparing with images. Thereafter, in the second photoacoustic image construction means 20, the photoacoustic data is corrected by the calculated amount of deviation, and a photoacoustic image is generated again.

  FIG. 7 shows an ultrasonic image, and FIG. 8 shows a provisionally generated photoacoustic image. It is assumed that the measurement object in the photoacoustic image is a blood vessel portion. The blood vessel portion appears in both the ultrasonic image shown in FIG. 7 and the photoacoustic image shown in FIG. For example, the shift amount detection unit 19 shifts the pixel value of the ultrasonic image and the photoacoustic image while shifting the photoacoustic image by one pixel in the depth direction (one time in the time direction) within a predetermined range with respect to the ultrasonic image. The sum of the differences from the pixel values is calculated as the correlation between the two images. It is considered that this correlation takes a maximum value when the amount of shift is such that the positions of the blood vessel portion included in the ultrasonic image and the blood vessel portion included in the photoacoustic image overlap. The deviation amount detection means 19 detects the deviation amount when the correlation value is maximum as the deviation amount.

  FIG. 9 shows the regenerated photoacoustic image. In the tentatively generated photoacoustic image shown in FIG. 8, for example, in delay addition, data of each element is added with a delay time based on a position shifted from the original position (see FIG. 6). The image is blurred. In the present embodiment, in the second photoacoustic image construction means 20, the time axis (position in the depth direction) is corrected by the amount of deviation between the ultrasonic image and the photoacoustic image, and the photoacoustic is based on the photoacoustic data. Regenerate the image. By doing so, it is possible to correct the positional deviation in the depth direction of the photoacoustic generation source even when there is a variation in the time from the output of the light irradiation trigger to the actual light irradiation. Further, by re-configuring the photoacoustic image in a state where the position of the photoacoustic generation source is corrected, the image quality can be improved with respect to the provisionally generated photoacoustic image.

  Here, when considering that the photoacoustic image and the ultrasonic image are superimposed (combined) or displayed side by side, the first photoacoustic image construction means 17 is only a problem if only positional deviation is a problem. The position of the photoacoustic image generated in step (FIG. 8) may be corrected by the amount of deviation and superimposed on the ultrasonic image. However, since the photoacoustic image generated by the first photoacoustic image constructing unit 17 is generated based on an incorrect position, a blurred photoacoustic image, an ultrasonic image, and Will be synthesized. In the present embodiment, since the time axis of the photoacoustic signal is corrected and regenerated by the detected deviation, the photoacoustic data is corrected and the generation of the photoacoustic image is performed again. When combining and displaying the photoacoustic image, it is possible to combine the photoacoustic image generated based on the original position and the high-quality image and the ultrasonic image.

  In the above description of the embodiment, the delay addition method and the CBP method have been described as the photoacoustic image generation method, but the photoacoustic image generation method is not particularly limited. For example, the first photoacoustic image construction unit 17 and the second photoacoustic image construction unit 20 may generate a photoacoustic image by the Hough transform method. Or the 1st photoacoustic image construction means 17 and the 2nd photoacoustic image construction means 20 may produce | generate a photoacoustic image by a Fourier-transform method.

  Next, a second embodiment of the present invention will be described. FIG. 10 shows a photoacoustic image diagnostic apparatus according to the second embodiment of the present invention. The photoacoustic image diagnostic apparatus 10a of this embodiment includes a feature point extraction unit 23 in addition to the configuration of the photoacoustic image diagnostic apparatus 10 of the first embodiment shown in FIG. Other configurations are the same as those of the first embodiment.

  The feature point extraction means 23 extracts a predetermined feature point from the ultrasonic image and generates a feature point image. The feature point extraction means 23 extracts, for example, feature points corresponding to the blood vessel portion from the ultrasonic image, and generates a blood vessel image composed of the extracted blood vessel portion as a feature point image. The shift amount detection means 19 detects the shift amount between the two images based on the feature point image obtained by extracting the feature points from the ultrasonic image and the photoacoustic image. The shift amount detection means 19 obtains a correlation between both images while shifting the relative positions of the feature point image and the photoacoustic image, for example, and detects the shift amount of the position between the images based on the obtained correlation.

  The operation after detecting the deviation is the same as that in the first embodiment. That is, the second photoacoustic image construction means 20 corrects the photoacoustic signal by the detected deviation and reproduces the photoacoustic image. Also in this embodiment, the same effect as that obtained in the first embodiment can be obtained. That is, the measurement object can be displayed at the original position, and the image quality of the photoacoustic image can be improved. In the present embodiment, for example, when detecting the amount of deviation between the ultrasonic wave image and the photoacoustic image based on the correlation, the amount of deviation between the images can be detected after narrowing down the comparison target. . For example, by extracting a portion imaged as a photoacoustic image as a feature point, a deviation amount between the ultrasonic image (feature point image) and the photoacoustic image can be obtained with high accuracy.

  In each of the above embodiments, an example in which the photoacoustic image is regenerated only once using the detected shift amount is described, but the present invention is not limited to this. For example, the detection of the shift amount between the photoacoustic image and the ultrasonic image and the regeneration of the photoacoustic image based on the detected shift amount may be repeated a plurality of times. More specifically, in the flowchart shown in FIG. 4, after the second photoacoustic image construction unit 20 generates the photoacoustic image in step S <b> 8, the process returns to step S <b> 7. However, the amount of deviation may be detected based on the photoacoustic image and the ultrasonic image generated by the second photoacoustic image construction means 20. Then, it progresses to step S8 and produces | generates a photoacoustic image again based on the detected deviation | shift amount. In this case, for example, the loop may be terminated when the amount of deviation detected by the deviation amount detecting means 19 becomes equal to or less than a predetermined threshold value. When the detection of the deviation amount and the regeneration of the photoacoustic image are repeatedly performed, the image quality of the photoacoustic image is improved as the correction progresses. Therefore, the deviation error detected by the deviation amount detection unit 19 is reduced and regenerated. It is possible to further improve the image quality of the photoacoustic image.

  In each of the above embodiments, the shift amount between images is detected by calculating the correlation between the photoacoustic image and the ultrasonic image (feature point image), but the shift amount detection method is not limited to this. . For example, in the photoacoustic image diagnostic apparatus, a comparison point setting unit that sets comparison points corresponding to each other in the photoacoustic image and the ultrasonic image is provided, and the deviation amount detecting unit 19 is compared with the ultrasonic image. You may detect the deviation | shift amount of a point and the comparison point set with respect to the photoacoustic image. The comparison point setting means may perform, for example, feature analysis of the ultrasonic image and the photoacoustic image, and set the comparison point according to the analysis result. Alternatively, the comparison point setting means may prompt the user to set a comparison point and set the point designated by the user as a comparison point.

  As mentioned above, although this invention was demonstrated based on the suitable embodiment, the photoacoustic image diagnostic apparatus of this invention, the image generation method, and a program are not limited only to the said embodiment, The said embodiment is not limited. Those in which various modifications and changes have been made to the configuration are also included in the scope of the present invention.

10: Photoacoustic image diagnosis apparatus 11: Ultrasonic probe 12: AD conversion means 13: Trigger control means 14: Laser light source 15: Signal processing means 16: Mode switching means 17, 20: Photoacoustic image construction means 18: Super Sound image construction means 19: deviation amount detection means 21: image selection means 22: image display means 23: feature point extraction means

Claims (9)

An ultrasound image construction means for generating an ultrasound image;
Photoacoustic image construction means for generating a photoacoustic image based on a photoacoustic signal generated by light irradiated in the subject;
Based on the ultrasonic image and the photoacoustic image, provided with a shift amount detection means for detecting a shift amount in the time axis direction between the two images
The photoacoustic image diagnosing device, wherein the photoacoustic image constructing unit regenerates the photoacoustic image based on the detected deviation.   The photoacoustic image construction means corrects the time axis of the photoacoustic signal by the amount of deviation in the time axis direction detected by the deviation amount detection means, and regenerates the photoacoustic signal. The photoacoustic image diagnostic apparatus according to claim 1.   3. The reproduction of the photoacoustic image and the detection of the shift are repeatedly performed until the shift detected by the shift amount detection unit becomes a predetermined threshold value or less. The photoacoustic image diagnostic apparatus of description.   4. The deviation amount detection unit obtains a correlation between the ultrasonic image and the photoacoustic image, and detects the deviation amount based on the obtained correlation. The photoacoustic image diagnostic apparatus of description.   The image processing apparatus further includes a feature point extraction unit that extracts a predetermined feature point from the ultrasonic image to generate a feature point image, and the deviation amount detection unit obtains a correlation between the feature point image and the photoacoustic image, 4. The photoacoustic image diagnostic apparatus according to claim 1, wherein the shift amount is detected based on the obtained correlation.   The feature point extracting means extracts a feature point corresponding to a blood vessel portion from the ultrasonic image, and generates a blood vessel image composed of the extracted blood vessel portion as the feature point image. Item 6. The photoacoustic image diagnostic apparatus according to Item 5.   The deviation amount detecting means detects a deviation amount between a comparison point set for the ultrasonic image and a comparison point corresponding to the comparison point in the ultrasonic image set for the photoacoustic image. The photoacoustic image diagnostic apparatus according to any one of claims 1 to 3, wherein: Generating an ultrasound image based on the reflected acoustic signal for the ultrasound output in the subject;
Acquiring a photoacoustic signal generated by light irradiated in the subject, and generating a photoacoustic image based on the acquired photoacoustic signal;
Detecting a shift amount in the time axis direction between the two images based on the ultrasonic image and the photoacoustic image;
And regenerating the photoacoustic image based on the detected deviation. On the computer,
A procedure for generating an ultrasound image based on a reflected acoustic signal for the ultrasound output in the subject;
A procedure for acquiring a photoacoustic signal generated by light irradiated in a subject and generating a photoacoustic image based on the acquired photoacoustic signal;
Based on the ultrasonic image and the photoacoustic image, a procedure for detecting a shift amount in the time axis direction between the two images;
A program for causing the photoacoustic image to be regenerated based on the detected deviation.