WO2014021105A1 - Ultrasonic diagnostic device - Google Patents

Abstract

Provided is an ultrasonic diagnostic device that can easily acquire a diagnostic image of a diagnostic site behind an obstacle. In order for a sector scan range to reach a diagnostic site behind the obstacle, which becomes a propagation obstacle for scanning lines comprising a transmission beam and a reception beam, the scanning lines are scanned by positioning scanning centers of a sector scan in a sector scan range and setting at least one scanning center, and setting the scanning conditions of the sector scan so as to pass through the set scanning center (16).

Description

Ultrasonic diagnostic equipment

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrasonic diagnostic apparatus, and more particularly to an ultrasonic diagnostic apparatus that generates and displays various diagnostic images by fan-scanning an area including a diagnostic region of a subject with a scanning line of an ultrasonic transmission / reception beam.

The ultrasonic diagnostic apparatus transmits an ultrasonic wave to the inside of the subject using an ultrasonic probe, receives an ultrasonic reflected echo signal corresponding to the structure of the living tissue from the inside of the subject, for example, an ultrasonic tomographic image or the like A diagnostic image is generated and displayed. In particular, in acquiring a diagnostic image for cardiac function diagnosis or the like, the diagnostic region is often fan-shaped scanned with an ultrasonic transmission / reception beam using a phased array. The phased array type ultrasonic probe controls the phase of ultrasonic waves radiated from a plurality of transducers having transmission / reception apertures (hereinafter referred to simply as apertures) to focus the ultrasonic waves at a specific focusing point. Transmit beams and receive beams can be generated and the beam direction can be deflected. Therefore, it is generally employed to obtain a diagnostic image by performing sector scan (sector scan) using a pair of transmission beam and reception beam as scanning lines by electronic scanning.

By the way, when transmitting and receiving ultrasonic waves from the body surface of the subject to the heart using an ultrasonic probe, reflection, diffuse reflection, diffraction, etc. of ultrasonic waves by obstacles such as ribs that obstruct ultrasonic propagation For this reason, there is a problem that artifacts occur in the diagnostic image. Therefore, intercostal scanning in which a scanning line is emitted from an acoustic window between the ribs (acoustic window) is generally employed. However, intercostal scanning also produces artifacts unique to intercostal scanning, such as jamming noise and shadow artifacts. Further, there are general speckle noises and the like, and these artifacts hinder image diagnosis.

In order to avoid artifacts peculiar to intercostal scanning, for example, when an ultrasonic probe in which a plurality of transducers are arranged contacts a subject across a plurality of ribs, reflection received by the ultrasonic probe It has been proposed to detect the position of the rib based on the intensity distribution of the echo signal and stop driving the vibrator located directly above the rib (Patent Document 1).

In addition, in order to reduce the influence of ribs, multiple transducers of the ultrasound probe are arranged in a concave shape in the scanning direction, and the scanning center (fan apex) of sector scanning is set between the ribs. It has been proposed to form a fan-shaped scanning region in the subject further forward than that, that is, behind the ribs (for example, Patent Document 2).

In order to reduce general speckle noise in ultrasonic diagnosis, it has been proposed to scan a diagnostic region from different directions to obtain a plurality of diagnostic images and to spatially synthesize those diagnostic images (for example, Patent Document 3). In particular, according to the document 3, an ultrasonic probe driving method is proposed in which a phased array is equivalent to a curved array in order to acquire a plurality of diagnostic images for spatial synthesis.

Furthermore, for diagnosis of organs that move relatively quickly, such as the heart, it is desirable to obtain diagnostic images at a high frame rate. Therefore, a plurality of apertures are set, transmission beams modulated with different codes are transmitted from the respective apertures, reception signals received at the respective apertures are decoded to generate reception beams, and a plurality of transmission beams are generated at the same time. It has been proposed to increase the frame rate by forming a reception beam (for example, Patent Document 4).

JP 2002-253548 A JP 2000-201928 A Special table 2010-538746 JP 2002-233526 A

By the way, in the case of the diagnosis of the heart, it is common to make a diagnosis based on the diagnostic images of the heart acquired from various angles, but the acoustic window between the ribs varies depending on the position of the ribs. That is, the size of the acoustic window between the ribs changes depending on the position, and the depth from the body surface to the ribs changes. However, in the techniques described in Patent Documents 1 to 4, it is not considered that the size of the acoustic window and the depth position of the ribs change depending on the position of the ribs. Therefore, diagnostic images of the heart are obtained from various angles. If you are restricted. For example, according to Patent Document 1, since the intercostal scanning is difficult at a position where the rib correlation window is narrow, it may be impossible to acquire a diagnostic image of the heart from various angles. According to Patent Document 2, since the scanning center is determined by the concave surface on which a plurality of transducers are arranged, the intercostal scanning may not be performed when the depth of the ribs is changed. Such a problem is not limited to obstacles such as the ribs, but is a common problem when obtaining a diagnostic image by imaging the brain tissue from the gap of the skull such as the temple. Furthermore, not only when acquiring a diagnostic image from a gap between obstacles such as bones, even in the case of one obstacle, there is a case where it is desired to image a diagnostic part on the back side of the obstacle viewed from the ultrasonic probe side. is there. Such a case is not considered in the techniques of Patent Documents 1 and 2.

On the other hand, according to Patent Document 3, a tomographic image of a diagnostic part can be acquired from various angles, and speckle noise and the like can be reduced by image synthesis. There is no consideration for fan-shaped scanning of a site or a diagnostic site on the back side of an obstacle. Further, Patent Document 4 also does not take into consideration obtaining a diagnostic image at a high frame rate by avoiding an obstacle such as a rib.

A first problem to be solved by the present invention is to provide an ultrasonic diagnostic apparatus that can easily acquire a diagnostic image of a diagnostic part on the back side of an obstacle.
A second problem is to provide an ultrasonic diagnostic apparatus capable of reducing the influence of artifacts in addition to the first problem.

In a first aspect of the present invention that solves the first problem, an ultrasonic probe that is used in contact with a subject, and the ultrasonic probe is driven to irradiate the subject. A transmission / reception unit that generates a transmission beam and receives a reflected echo signal received by the ultrasound probe to generate a reception beam; and a diagnosis in the subject using the transmission beam and the reception beam as scanning lines A control unit that controls the transmission / reception unit so as to scan the region in a sector shape, an image configuration unit that generates a diagnostic image based on the reception beam generated by scanning by the transmission / reception unit, and a display that displays the diagnostic image A fan-shaped scanning range such that the fan-shaped scanning range extends to the diagnostic part on the back side of the obstacle that is a transmission obstacle of the transmission beam based on the tomographic image of the diagnostic part generated by the image constructing part. Fan-shaped running A scanning center setting unit that sets at least one scanning center and sets the scanning condition of the sector scan so as to pass through the set scanning center, and the transmission / reception is performed according to the scanning condition It is characterized by controlling the part.

That is, in the first aspect of the present invention, at least one scan center of the sector scan is set so that the sector scan range extends to the diagnostic site on the back side of the obstacle, and the scan condition for each scan center, that is, The maximum scanning angle, scanning line pitch, number of scanning lines, aperture, focusing position, etc. can be set. As a result, even if the depth of the obstacle from the body surface is different, the scanning center which is the apex of the sector scan corresponding to this is easily moved to the position where the sector scan range extends to the diagnosis part on the back side of the obstacle. Can be changed. As a result, the scanning line can be fan-shaped scanned to the back of the obstacle without being obstructed by the obstacle, so that diagnostic images can be easily acquired even from different angles with the position of the ultrasound probe changed. Can do.

According to a second aspect of the present invention, in the first aspect, a plurality of fan-shaped scanning centers are set at a position where the fan-shaped scanning range extends to the diagnostic part on the back side of the obstacle, and the scanning is performed for each scanning center. A plurality of scanning conditions are set so as to pass through the center, the transmission / reception unit is controlled according to each scanning condition, and the image construction unit synthesizes a plurality of the diagnostic images generated for each of the scanning centers. An image is generated. According to this, the influence of the artifact can be reduced.

According to the first aspect of the present invention, it is possible to easily obtain a diagnostic image of a diagnostic part on the back side of an obstacle.

Further, according to the second aspect of the present invention, in addition to the effect of the first aspect, the influence of the artifact can be reduced.

It is a block block diagram of Example 1 of the ultrasonic diagnostic apparatus of the present invention. It is a figure which shows an example of the intercostal scan of the prior art example which demonstrates the solution subject of this invention. It is a figure which shows the scan 1 example between the ribs by Example 1 of this invention. It is a figure which shows the scanning example 2 between the ribs by Example 1 of this invention. It is a figure which shows the scanning example 3 between the ribs by Example 1 of this invention. It is a figure which shows the scanning example 4 between ribs by Example 1 of this invention. FIG. 6 is a diagram for explaining an example of automatically setting a scanning center and scanning conditions according to the first embodiment. It is a block block diagram of Example 2 of the ultrasonic diagnostic apparatus of this invention. It is a figure which shows the scan 1 example between the ribs by Example 2. FIG. 6 is a diagram illustrating an example of a code-modulated transmission signal according to Embodiment 2. FIG. FIG. 6 is a diagram illustrating an example of an ultrasonic transmission signal applied to each transducer according to the second embodiment. It is a schematic diagram of the sound field distribution of the example of the ultrasonic transmission signal of FIG. FIG. 10 is a diagram illustrating another example of an ultrasonic transmission signal applied to each transducer according to the second embodiment. It is a schematic diagram of the sound field distribution of the example of the ultrasonic transmission signal of FIG. It is a block block diagram of embodiment of the ultrasonic diagnosing device of this invention. It is a figure which shows an example of the intercostal scan of the prior art example which demonstrates the solution subject of this invention. It is a figure explaining the intercostal imaging of Example 3 using the ultrasonic diagnostic apparatus of this invention. It is a figure which shows the timing chart of transmission and reception of the imaging between furrows of Example 3. FIG. It is a figure explaining the example which carries out the space synthesis | combination of the several image imaged by the intercostal imaging of Example 3. FIG. It is a figure explaining the imaging by Example 3 of this invention when there is no obstruction. It is a figure explaining the intercostal imaging of Example 4 using the ultrasonic diagnostic apparatus of this invention. FIG. 10 is a diagram for explaining a modification of the fourth embodiment. FIG. 10 is a diagram for explaining another modified example of the fourth embodiment. FIG. 10 is a diagram for explaining still another modification of the fourth embodiment. It is a figure explaining the modification which sets multiple virtual point sound sources of Example 4 to the depth direction. FIG. 10 is a diagram illustrating a modification in which the virtual point sound source according to the fourth embodiment is set on the transmission / reception surface of the ultrasonic probe. FIG. 10 is a diagram illustrating a modification in which the virtual point sound source according to the fourth embodiment is set on the inner side of the transmission / reception surface of the ultrasonic probe. It is a block block diagram of Example 5 of the ultrasonic diagnostic apparatus of this invention. It is a figure explaining the imaging between the ribs of Example 5. FIG. FIG. 10 is a diagram illustrating a specific configuration of a transmission modulation unit according to the fifth embodiment. It is a figure which shows the computing equation and waveform of the code modulation transmission signal of Example 5. It is a figure which shows the time waveform of the code modulation transmission signal applied to the transmission aperture which each transmits a plane wave beam to three deflection directions. It is a schematic diagram which shows the sound field distribution of the ultrasonic wave of the plane wave beam transmitted to three deflection directions. FIG. 10 is a specific configuration diagram of a reception beamformer and a reception demodulation unit according to the fifth embodiment. It is a figure which shows the computing equation and waveform of the code demodulation receiving signal of Example 5. It is a figure which shows the time waveform of the code modulation transmission signal applied to the transmission aperture which each transmits a plane wave beam to two virtual point sound sources. It is a schematic diagram which shows the sound field distribution of the ultrasonic wave of the plane wave beam transmitted to two virtual point sound sources.

An embodiment of an ultrasonic diagnostic apparatus to which the present invention is applied will be described with reference to the drawings.
(Example 1)
As shown in FIG. 1, the ultrasonic diagnostic apparatus 1 according to the present embodiment generates an ultrasonic probe 2 that is used in contact with a subject 13 and an ultrasonic signal that drives the ultrasonic probe 2. At the same time, a pulsar receiver 4 that receives a reflected echo signal received by the ultrasonic probe 2 to generate a reception signal, and a transmission beam that controls the pulsar receiver 4 to form a transmission beam that is irradiated into the subject 13. The former 3 is formed with a reception beam former 5 that inputs a reception signal output from the pulser receiver 4 and forms a reception beam. The transmission beamformer 3, the pulser receiver 4, and the reception beamformer 5 form a transmission / reception unit of the present invention.

The reception beam data output from the reception beamformer 5 is input to the space synthesis unit 6. The spatial synthesis unit 6 performs spatial synthesis using received frame data composed of received beam data for spatial synthesis stored in the spatial synthesis memory 7. The image processing unit 8 extracts diagnostic information from the received frame data synthesized by the space synthesis unit 6, generates a diagnostic image, and displays it on the display unit 9. The space composition unit 6, the space composition memory 7, and the image processing unit 8 form an image configuration unit of the present invention.

The transmission beamformer 3, the reception beamformer 5, the space synthesis unit 6, the image processing unit 8, and the display unit 9 are connected to a control unit 10 and a user interface (UI) 11 via a system bus 12, respectively. Necessary data and control commands can be transmitted and received. The control unit 10 controls the entire ultrasound diagnostic apparatus 1 and also controls the transmission beamformer 3 and the reception beamformer 5 to transmit the transmission beam transmitted to the subject 13 and the reflected echo signal received from the subject 13. A receiving beam is formed. Further, the control unit 10 controls the transmission beamformer 3 and the reception beamformer 5 so as to perform sector scanning using the transmission beam and the reception beam as scanning lines. The user interface (UI) 11 includes an input setting unit that allows an operator to operate and operate the ultrasonic diagnostic apparatus 1.

The ultrasonic probe 2 is a phased array, is formed by arranging a plurality of transducers, and has a function of transmitting and receiving ultrasonic waves to and from the subject 13. The pulsar receiver 4 drives the ultrasonic probe 2 to generate a transmission pulse for generating ultrasonic waves, and amplifies the reflected echo signal received by the ultrasonic probe 2 with a predetermined gain. Generate a received signal. The transmission beam former 3 forms a transmission beam corresponding to the set depth at the convergence point of the transmitted ultrasonic wave, and drives and controls the ultrasonic probe 2 via the pulser receiver 4. The reception beamformer 5 receives a reception signal from the pulsar receiver 4 and forms a reception beam that is phased according to one or more set convergence points. As a result, a scanning line formed by combining the transmission beam and the reception beam is formed. The image processing unit 8 obtains diagnostic image data by performing various filters, detection, reflection intensity image luminance conversion, blood flow velocity calculation, scan conversion processing, image of each mode, and overlay of characters and scales. The display unit 9 displays the diagnostic image data generated by the image processing unit 8 on the screen as a diagnostic image.

Here, the operation of the characteristic part of the ultrasonic diagnostic apparatus 1 of the present embodiment will be described. The control unit 10 includes a CPU, a main memory, an HDD, and the like, and controls each unit of the ultrasonic diagnostic apparatus 1 via a system bus 12, a serial interface, a network, and the like. That is, the control unit 10 controls the operation of each unit of the ultrasonic diagnostic apparatus 1 in accordance with an instruction according to an operation of the operator input from the user interface 11 connected to the system bus 12. The user interface 11 includes a trackball, a keyboard, a switch, and the like.

The spatial synthesis unit 6 stores the reception beam data of at least one frame in the spatial synthesis memory 7, and receives the reception beam data of the second and subsequent frames and the reception beam data at the corresponding position of the stored frame. The combined reception beam data is generated on a frame basis. A known synthesis method can be applied to the spatial synthesis. For example, the reception beam data of a plurality of frames is added and averaged in units of pixels to generate synthesis reception frame data composed of the synthesis reception beam data. The image processing unit 8 performs filtering processing, detection processing, reflection intensity image luminance conversion processing, blood flow velocity calculation, scan conversion on each combined reception beam data of the combined reception frame data output from the spatial combining unit 6 as necessary. A desired diagnostic image is generated by performing processing such as processing. That is, a plurality of diagnostic images are generated on the basis of the received beam generated by fan-shaped scanning for each scanning center, which will be described later, by the space synthesis unit 6, the space synthesis memory 7, and the image processing unit 8. An image configuration unit that generates a combined diagnostic image by combining the diagnostic images is formed.

The diagnostic image generation method of the first embodiment configured as described above will be described with reference to FIGS. In the present embodiment, as illustrated in FIG. 1, it is assumed that a diagnostic image of the heart 14 is acquired as a diagnostic site in the subject 13. As shown in the figure, a rib 15 that is an obstacle is located between the ultrasound probe 2 and the heart 14. When a diagnostic image is acquired by fan scanning using a conventional phased array ultrasonic probe 2, as shown in FIG. 2, the scanning center 16 of the fan scanning is set at the ultrasonic radiation surface of the ultrasonic probe 2. And set at the center of the array of the plurality of transducers. In this case, since an area 18 where the rib 15 blocks the scanning line 17 with respect to the heart 14 is generated, an image in which a part of the heart 14 is hidden by an acoustic shadow is obtained. Further, as a result of the irregular reflection of ultrasonic waves at the ribs 15, artifacts 119 are generated, which hinders diagnosis.

Therefore, in this embodiment, as shown in FIG. 3, the scanning center 16 is set in the acoustic window which is a gap formed between the two ribs 15a and 15b. FIG. 3 shows an example in which the scanning centers 16a, b, c are set at three points on the line connecting the narrowest points 120a, b of the narrowest gap between the two ribs 15a, b. However, the present invention is not limited to this. For example, the scanning center 16 may be set at least at one point on the line connecting the narrowest points 120a and 120b between the ribs 15a and 15b. In short, the scanning center 16 is set to at least one point so that the fan-shaped scanning range extends to the diagnostic part on the back side of one rib 15a or 15b that is an obstacle. The setting of the scanning center 16 is, for example, a tomographic image of the diagnostic region 14 including the rib 15 obtained by bringing the ultrasound probe 2 into contact with the body surface of the subject 13 in a preparation stage for acquiring a diagnostic image of the heart 14. Can be displayed on the display unit 9, and the operator can set the scanning center 16 on the tomographic image from the user interface 11 constituting the scanning center setting unit. Further, as described later, the scanning center 16 can be automatically set by the control unit 10.

When the scanning center 16 is set by the user interface 11, the control unit 10 sets a scanning condition for fan-shaped scanning that passes through the set scanning center 16. The scanning conditions are parameters including the maximum scanning angle of the fan-shaped scanning range, the scanning line pitch, the number of scanning lines, the aperture, the focusing position, and the like, and are set according to preset criteria for the scanning conditions. Then, the control unit 10 controls the transmission beamformer 3 and the reception beamformer 5 according to the set scanning conditions, transmits the transmission beam to the subject 13 via the pulser receiver 4 and the ultrasonic probe 2, and A reception beam is generated from the reflected echo signal.

In FIG. 3, for the sake of simplicity, three scanning lines 17 are shown for each of the scanning centers 16a to 16c. That is, although the center of the sector scan range and the scan lines at both ends are shown, the number of normal scan lines is several tens to several hundreds. The three received beam data obtained by the sector scans of the scanning centers 16a, 16b, and 16c are stored in the spatial synthesis memory 7 by the spatial synthesis unit 6, and the scanning area of the frame data composed of the respective received beam data is stored. The overlapping reception beam data in the same space is spatially synthesized, and a composite diagnostic image is generated by the image processing unit 8.

As described above, according to the sector scan shown in FIG. 3, since the scanning center 16 can be set between the ribs 15 that are the obstacles and the ultrasonic beam can be transmitted and received, the heart 14 that is the diagnostic site is attached to the ribs 15. It is possible to draw without being hidden by the acoustic shadow. Therefore, even if the size of the gap between the ribs 15 and the depth from the body surface change depending on the position of the ultrasound probe 2, the scanning center 16 that is the apex of the fan-shaped scanning is correspondingly affected by a plurality of obstacles. Since it can be easily changed to a gap between objects, the scanning line can be scanned in a fan shape without being obstructed by an obstacle. Thereby, it is possible to easily acquire diagnostic images viewed from different angles by changing the position of the ultrasound probe 2 in various ways.

Further, since unnecessary irregular reflection by the ribs 15 can be reduced, artifacts such as jamming noise can be reduced. In addition, frame data consisting of received beam data obtained by setting a plurality of scanning centers 16 and sequentially fan-shaped scanning can be acquired, and these frame data can be spatially combined to form a diagnostic image, thus reducing speckle noise. can do.

FIG. 4 shows a modification of FIG. 4 (b) shows the number of scanning lines of fan-shaped scanning of the scanning center 16b set near the centers of the ribs 15a, b in FIG. 3 as shown in FIGS. 4 (a) and 4 (c). The scanning centers 16a and 16c set close to each other are increased from the number of scanning lines in the sector scanning. As described above, the image display range can be expanded by increasing the number of scanning lines of the fan-shaped scanning of the scanning center 16 which is relatively far from the rib 15 and is located near the center of the gap between the two adjacent ribs 15. it can. 3 and 4, the number of scanning lines is set to be bilaterally symmetric, but the display range can be expanded by changing the left / right ratio.

FIG. 5 shows an example in which the two scanning centers 16a and 16c are set at positions close to the inside of the two ribs 15a and 15b and the number of scanning lines is increased. Thus, the effect of spatial synthesis can be enhanced by changing the position of the scanning center 16 and the scanning conditions. Further, by adjusting the scanning line density, the effect of improving the spatial resolution and the effect of reducing the artifact can be adjusted.

In the example of setting the scanning center shown in FIGS. 3 to 5, the case where a plurality of scanning centers are set on the line connecting the narrowest points 120a and 120b of the narrowest gap between the two ribs 15 is shown. However, the present invention is not limited to this, and two points can be set by shifting the scanning center 16 in the depth direction as shown in FIG. Even in the case of this example, two sets of received beam data related to the diagnostic image of the heart 14 can be acquired. Therefore, by combining these spatially, artifacts due to speckle noise or the like can be reduced. The example of FIG. 6 is effective when the interval between the ribs 15 that are obstacles is narrow. In particular, as an example in which the gap between obstacles is narrow, there is a case where a diagnostic image is obtained by imaging brain tissue from the gap of the temple.

With reference to FIG. 7, an example in which the scanning center 16 and the scanning conditions are automatically set in the control unit 10 of the first embodiment will be described. In FIG. 7, the tomographic image including the rib 15 is obtained by operating the user interface 11 at the preparation stage for obtaining the diagnostic image of the heart 14 and bringing the ultrasound probe 2 into contact with the body surface of the subject 13. Is done. Based on the tomographic image of FIG. 7, as described above, the operator can set the scanning center 16 from the user interface 11 including the scanning center setting unit. In contrast, the control unit 10 determines the distance A between the centers of the ribs 15B1 and 15B2 displayed in the tomographic image of FIG. 7, the maximum width W of the ribs 15B1 and 15B2, and the distance between the centers of the ribs 15B1 and 15B2 from the ultrasonic radiation surface. The distance y _O to the center O of the straight line connecting is obtained. Then, the center O is set as the scanning center 16, and a line connecting the predetermined center C of the aperture D and the scanning center 16 is set as the center line of the transmission / reception beam to obtain the deflection angle θ of the scanning line. Further, it is confirmed that the transmission / reception beam focusing point F set in advance from the user interface 11 and the like and the transducer ch at both ends of the aperture D are connected, and the line connecting them is not blocked by B1 and B2 of the rib 15. . Therefore, a deflection angle θth that passes through the converging point F and is not obstructed by the ribs 15B1 and 15B2 is calculated in advance, and a straight deflection angle θ ′ connecting the vibrator ch at both ends of the aperture D and the converging point F is θth. Confirm that it is less than In the case of θ ′ ≧ θth, the aperture D is changed small or the scanning line deflection angle θ is changed small so that θ ′ <θth. In this way, the control center 10 can automatically set the scanning center 16 and set the maximum scanning angle and aperture of the scanning conditions. In addition, if the scanning line pitch, the number of scanning lines, and the focusing position are set in advance, the control unit 10 can control the transmission / reception beam related to the sector scanning.

Although Example 1 demonstrated above demonstrated the example which images the diagnostic site | part of the back of the ribs 15a and b from the clearance gap between the two ribs 15a and b, this invention is not limited to this. That is, according to Example 1, it is possible to obtain a diagnostic image of a diagnostic site on the back side of one rib 15a or 15b. From this, even when there is only one obstacle that causes transmission / reception beam propagation obstruction, by setting at least one scan center of the sector scan so that the sector scan range extends to the diagnostic part on the back side of the obstacle The diagnostic image of the diagnostic part on the back side of the obstacle can be easily acquired. In this case, the scanning center setting unit can set the scanning center at a position where the fan-shaped scanning line at one end of the fan-shaped scanning range is not obstructed by the obstacle. Further, the scanning center can be set in the spatial region on the side surface of the obstacle as viewed from the ultrasonic probe. Further, when a plurality of scanning centers are set, the image configuration unit can improve the image quality of the diagnostic image by generating a diagnostic image by combining a plurality of diagnostic images generated for each scanning center.

(Example 2)
A second embodiment of an ultrasonic diagnostic apparatus to which the present invention is applied will be described with reference to FIGS. FIG. 8 is a block diagram of the ultrasonic diagnostic apparatus 1 of the present embodiment. This embodiment is characterized in that the transmission beam is code-modulated and the reception beam is code-demodulated to generate reception beam data. Therefore, the difference from the first embodiment shown in FIG. 1 is that the transmission modulation unit 21 is provided to code-modulate the transmission beam data generated by the transmission beamformer 3, and the reception demodulation unit 22 is provided to The reception beam data to be output is code-demodulated and output to the space synthesis unit 6. The transmission modulation unit 21 and the reception demodulation unit 22 are connected to the control unit 10 and the user interface 11 via the system bus 12, respectively. Since other configurations are the same as those of the first embodiment, the same reference numerals are given and the description thereof is omitted.

The transmission modulation unit 21 modulates a transmission beam to be transmitted using a code coefficient such as Barker, Golay, or Chirp. The reception demodulation unit 22 demodulates the reception beam using a code demodulation coefficient corresponding to the code modulated by the transmission modulation unit 21.

FIG. 9 shows an example in which a diagnostic image of the heart 14 is acquired by fan scanning using the gap formed between the three ribs 15a, 15b and 15c at the scanning center 16 of the fan scanning. explain. In the present embodiment, two scanning centers 16-1 and 16-2 are set using the user interface 11 in the gap between the three ribs 15a, b, and c. The control unit 10 sets parameters including the maximum scanning angle of the fan-shaped scanning range, the scanning line pitch, the number of scanning lines, the aperture, the focusing position, and the like for the scanning centers 16-1 and 16-2 in accordance with preset scanning conditions. The transmission beamformer 3 and the reception beamformer 5 are controlled to perform sector scanning. In the example of FIG. 9, a transmission / reception beam is formed at two scanning centers 16-1 and 16-2 from one ultrasonic probe 2 at the same time and scanned. Two received beam data respectively obtained at the two points of the scanning centers 16-1 and 16-2 are stored in the space synthesizing memory 7 by the space synthesizing unit 6, and are spatially synthesized as in the first embodiment. However, since transmission and reception beams are mixed in the same fan-shaped region, it is necessary to avoid such contamination.

Therefore, in this embodiment, the two transmission beams related to the sector scan of the scanning centers 16-1 and 16-2 are transmitted by performing different code modulation, and the received beam is code-demodulated with a corresponding code. Thus, the transmission beam and the reception beam are associated with each other. As a result, two parallel processes can be performed at the same time, so that it is possible to separate the two transmission / reception beams related to the sector scans of the respective scan centers 16-1 and 16-2, and to prevent their contamination.

For example, a code-modulated transmission signal generated by the transmission modulation unit 21 when code modulation is performed using two of four types of different codes of M = 28 described in Patent Document 4 will be described. The first code modulation transmission signal A corresponding to the scanning center 16-1 and the second code modulation transmission signal B corresponding to the scanning center 16-2 are fundamental wave: s, first transmission code: CA = [ -, +, +,-, +, +,-, +, +,-, +,-, +,-, +, +, +, +, +, +,-,-,-, +, +, −, −, −], Second transmission code: CB = [−, +, +, +, −, −, −, −, +, +, +, −, +, +, +, −, +, +, +,-, +, +,-, +,-,-, +,-], It can be expressed by the following equation. In this example, “+” sign means normal phase and “−” sign means reverse phase. In the following expression, “*” represents convolution integration processing.
A = s * CA
B = s * CB
FIG. 10 shows an example of the first code modulation transmission signal A and the second code modulation transmission signal B when the fundamental wave: S is a sin wave (one wave number).

Next, an example of the transmission operation of this embodiment will be described with reference to FIGS. As shown in FIG. 12, it is assumed that the first to third ribs 15a to 15c are positioned with respect to the ultrasonic probe 2 having the transducers ch01 to ch38. Here, on the user interface 11, the first scanning center 16-1 is disposed between the first rib 15a and the second rib 15b, and the second rib 15b is interposed between the second rib 15b and the third rib 15c. A scanning center 16-2 is arranged. The control unit 10 calculates the positions of the first scanning center 16-1 and the second scanning center 16-2, the deflection angle θ of the transmission / reception beam, the depth of the converging position 19, and the transmission aperture, To control. Here, the transmission aperture is calculated so as to be narrower than the interval between the ribs from the information on the transmission frequency, the focusing position, the deflection angle, and the transducer pitch so that the transmission / reception beam is not blocked by the rib 15. Further, the delay amount of each transducer for converging the transmission beam is calculated from the distance between each transducer within the aperture and the focal position and the sound speed of the subject 13.

11 and 12 show an example in which a transmission beam having a deflection angle of + 45 ° is simultaneously formed from the first aperture and the second aperture. FIG. 11 shows an example of a time waveform of an ultrasonic transmission signal applied to each transducer ch01 to ch38. In this example, the first aperture is ch17 to ch24, and the second aperture is 8ch each of ch31 to ch38. The further to the right, the slower the time. In the first apertures ch17 to ch24, the code-modulated transmission signal A that has been subjected to delay processing is the earliest ch24 and the latest ch17 is applied as an ultrasonic transmission signal. In the second apertures ch31 to ch38, the code modulation transmission signal B that has been subjected to the delay processing of ch38 the earliest and ch31 the latest is applied as the ultrasonic transmission signal.

FIG. 12 shows an example of a sound field distribution when an ultrasonic transmission signal is applied as shown in FIG. The ultrasonic transmission signal applied to each transducer is converted from an electrical signal to an ultrasonic signal and propagates through the subject 13. Originally, it propagates due to the directivity characteristics of each transducer, but in FIG. 12, in order to easily understand that the transmission signal is phased and converged at the converging position 19, diffusion and display of a wavefront propagating in another direction are displayed. Is omitted. When the ultrasonic transmission signal subjected to the delay processing as shown in FIG. 11 is applied to the vibrators of the first aperture ch17 to ch24, the transmission beam is focused on the focusing position 19-1. Similarly, when the ultrasonic transmission signal subjected to the delay processing as shown in FIG. 11 is applied to the transducers of the second diameter ch31 to ch38, the transmission beam is focused on the focusing position 19-2. In this example, the scanning center 16-1 is disposed on a straight line connecting the center of the first aperture and the transmission beam 19-1 and the transmission beam connects the focus 19-2. A scanning center 16-2 is arranged on the straight line.

13 and 14 show an example in which a transmission beam having a deflection angle of 0 ° is simultaneously formed from the first aperture and the second aperture. FIG. 13 shows an example of a time waveform of an ultrasonic transmission signal applied to each transducer ch01 to ch38. In this example, the first aperture is ch07 to ch14, and the second aperture is 8ch each of ch21 to ch28. The further to the right, the slower the time. In the first apertures ch07 to ch14, the code-modulated transmission signal A that has been subjected to the delay processing of ch07 and ch14 and the latest of ch10 and ch11 is applied as an ultrasonic transmission signal. In the second apertures ch21 to ch28, the code-modulated transmission signal B that has been subjected to delay processing for ch21 and ch28 and for ch24 and ch25 the latest is applied as an ultrasonic transmission signal.

FIG. 14 shows an example of the sound field distribution when the ultrasonic transmission signal is applied as shown in FIG. The ultrasonic transmission signal applied to each transducer is converted from an electrical signal to an ultrasonic signal and propagates through the subject 13. Originally, it propagates due to the directivity characteristics of each vibration element, but in FIG. 14, in order to easily understand that the transmission signal is phased and converged at the convergence position 19, diffusion and display of a wavefront propagating in another direction are displayed. Is omitted. By applying the ultrasonic transmission signal subjected to delay processing as shown in FIG. 13 to the transducers of the first apertures ch07 to ch14, the transmission beam is focused at the focusing position 19-1. Similarly, by applying an ultrasonic transmission signal subjected to delay processing as shown in FIG. 13 to the transducers of the second apertures ch21 to ch28, the transmission beam is focused at the focusing position 19-2. In this example, the scanning center 16-1 is disposed on a straight line connecting the center of the first aperture and the focusing position 19-1, and the scanning center 16 is positioned on a straight line connecting the center of the second aperture and the focusing position 19-2. -2 is arranged.

Incidentally, when an ultrasonic transmission beam having a deflection angle of −45 ° is simultaneously formed from the first aperture and the second aperture, it is symmetrical with respect to the scanning centers 16-1 and 16-2 in FIGS. Position. Although reception is not shown in the figure, the reception beamformer 5 performs a delay process corresponding to the time for which the ultrasonic echoes are reflected from each scanning line and received by each transducer. Each reception beam is formed by performing as necessary on the reception signal amplified by the pulser receiver 4 corresponding to the aperture. In addition, the reception demodulating unit 22 demodulates the code modulation transmission signal A and the code modulation transmission signal B generated by the transmission modulation unit 21, using a code demodulation filter A and a code demodulation filter B, for example, a time inverse filter process or mismatch. It demodulates by defiltering.

As described above, according to the second embodiment, reception beam data of two scanning areas can be generated at the same time by code-modulating and code-demodulating the transmission / reception beams, and information on these scanning areas can be mutually converted. Can be separated to prevent contamination.

As described above, the present invention has been described based on the first and second embodiments. However, according to the present invention, by arbitrarily setting the position of the scanning center and the number of scanning lines from the situation such as the position and interval of the obstacle, Since ultrasound can be transmitted and received, the diagnostic site can be depicted without being hidden by the acoustic shadow of the obstacle.

Moreover, since unnecessary irregular reflections due to obstacles can be reduced, artifacts such as jamming noise can be reduced. Furthermore, speckle noise can be reduced because a plurality of scanning centers are set and sector scanning is performed on a plurality of sector regions and a plurality of received beam data obtained are spatially synthesized. Furthermore, since aperture, phasing, and code modulation / demodulation processing are performed for each scanning center, it is possible to generate spatial data in which mutual information is separated and contamination is prevented. In addition, since the frame rate can be increased, an optimal diagnostic image can be obtained.

Also, in the spatial synthesis, it is possible to synthesize by multiplying the coefficients when synthesizing so that the influence of the information of the spatial data far from the obstacle among the plurality of scanning centers becomes large. According to this, the influence of an obstacle can be reduced further. As this coefficient, for example, it is desirable to continuously apodize with respect to an array of scanning centers such as Hanning, Hamming, and Blackman.

In the embodiment, the example in which the transducers are arranged in a plane as the ultrasonic probe 2 is shown. However, the present invention is not limited to this, and the ultrasonic probe in which the transducers are arranged in a curved surface is also shown. Applicable. In short, any phased array having a function of deflecting the scanning line by controlling the phase and the delay amount can be applied. In the present invention, an example in which different code modulation / demodulation processing is performed for each scanning center has been described. However, different code modulation / demodulation processing can be performed in different scanning line orientations.

Also, the number of transmission / reception lines is set according to the set deflection direction θ so that the center transmission line of the plane wave beam is set between the ribs that are the obstacles, and the width of the plane wave beam is set between the ribs 15 that are the obstacles. And the pitch may be adjusted.

Next, an embodiment in which the number and pitch of transmission / reception lines are adjusted according to the set deflection direction θ will be described in detail.

The present embodiment relates to an ultrasonic diagnostic apparatus, and more particularly, to a technique for transmitting a plane wave of an ultrasonic wave to a diagnostic region and receiving a reflected echo signal in parallel to capture a diagnostic image at a high frame rate.

A conventional ultrasonic diagnostic apparatus transmits an ultrasonic wave inside a subject using an ultrasonic probe and receives an ultrasonic reflection echo signal corresponding to the structure of a living tissue from the inside of the subject. For example, an ultrasonic tomogram Such a diagnostic image is generated and displayed. In particular, in cardiac function diagnosis, a phased array is used and images are obtained by performing sector scan (sector scan) on the diagnostic region with ultrasonic transmission / reception beams. A phased array type ultrasound probe controls the phase of ultrasonic waves radiated from a plurality of transducers having a transmission / reception aperture (hereinafter simply referred to as “aperture” as appropriate) to focus the ultrasound on a specific point. Transmit beam and receive beam can be generated and the beam direction can be deflected. Therefore, it is generally employed to obtain a diagnostic image by performing sector scanning using a pair of transmission beam and reception beam as scanning lines by electronic scanning.

By the way, when transmitting and receiving ultrasonic waves from the body surface of the subject to the heart using an ultrasonic probe, reflection, diffuse reflection, diffraction, etc. of ultrasonic waves by obstacles such as ribs that obstruct ultrasonic propagation For this reason, there is a problem that artifacts occur in the diagnostic image. Therefore, intercostal scanning in which a scanning line is transmitted from an acoustic window between the ribs (acoustic window) is generally employed. However, intercostal scanning also produces artifacts unique to intercostal scanning, such as jamming noise and shadow artifacts. Further, there are general speckle noises and the like, and these artifacts hinder image diagnosis.

Therefore, as a technique for reducing the influence of obstacles, the radiation surface is set so that the sound ray center of the beam is set in front of the radiation surface and a sector portion is formed in the subject further ahead of the sound ray center. Has been proposed to be formed into a concave shape (for example, Japanese Patent Application Laid-Open No. 2000-201928). In addition, a diagnostic image of a relatively fast moving organ such as the heart is desired to be imaged at a high frame rate. In order to realize high frame rate imaging in an ultrasonic diagnostic apparatus, a technique using an unfocused transmission beam such as a plane wave has been proposed (for example, US Pat. No. 6,309,356).

By the way, in the case of the diagnosis of the heart, it is common to make a diagnosis based on the diagnostic images of the heart acquired from various angles, but the acoustic window between the ribs varies depending on the position of the ribs. That is, the size of the acoustic window between the ribs changes depending on the position, and the depth from the body surface to the ribs changes. However, since the technique described in the above patent document does not consider that the size of the acoustic window and the depth position of the ribs change depending on the position of the ribs, the diagnostic images of the heart are acquired from various angles. Limited by case.

For example, according to Japanese Patent Application Laid-Open No. 2000-201928, the scanning center is determined by the concave surface on which a plurality of transducers are arranged. Such problems are not limited to obstacles such as the ribs, but when imaging images of brain tissue on the back side (back side) of the skull from the gap of the skull, such as the temple, etc. This is also a common problem when obtaining a diagnostic image of a living tissue on the back side (back side) of an obstacle. Further, US Pat. No. 6,309,356 does not describe avoiding an obstacle.

The problem to be solved by the present embodiment is to provide an ultrasonic diagnostic apparatus capable of acquiring a diagnostic image of a living tissue located behind an obstacle of ultrasonic propagation at a high frame rate while suppressing artifacts. .

The first aspect of the present embodiment that solves the above-described problem is a transmission process of an ultrasonic probe that is used in contact with a subject and a plurality of transducers of the ultrasonic probe. An image for generating a diagnostic image based on the received signal processed by the receiving unit, a receiving unit for receiving and processing reflected echo signals received by the plurality of transducers of the ultrasonic probe A transmission unit, a display unit that displays the diagnostic image, a control unit that controls at least the transmission unit, the reception unit, and the image configuration unit; and an input unit that inputs a command to the control unit; The unit drives a plurality of n (n is a natural number) of the transducers corresponding to the transmission aperture set in the ultrasonic probe based on a control command given from the control unit, Plane wave consisting of n transmission lines in the set deflection direction And the receiving unit performs focus processing on a reflected echo signal received by a plurality of m (m is a natural number) of the transducers corresponding to a receiving aperture set in the ultrasonic probe. A reception beam is generated, frame data including a plurality of reception beams obtained by scanning a plurality of reception lines set based on the n transmission lines is generated, and the image configuration unit includes the reception unit The diagnostic image is generated based on the frame data generated in step (1).

According to the first aspect, the transmission unit transmits the unfocused transmission plane wave beam including n transmission lines in the set deflection direction in the subject from the n transmission apertures. Accordingly, a diagnostic image of a living tissue in a diagnostic region located on the back side of an obstacle for ultrasonic propagation can be captured with reduced artifacts. In addition, since the plane wave beam is transmitted, the ultrasonic wave can be transmitted to the entire diagnosis region by one transmission without scanning. In addition, since time required for scanning is unnecessary, the frame rate can be increased by performing parallel reception. That is, in the receiving unit, the reflected echo signals received by the m transducers corresponding to the receiving apertures are focused, and a plurality of receiving beams are set for a plurality of receiving lines set corresponding to the plurality of transmitting lines. Is generated. Since frame data is generated by a plurality of reception beams, a diagnostic image can be taken at a high frame rate. Further, since the reception beam is generated by focusing and processing the reflected echo signal, the SN ratio of the reception signal can be increased, and a diagnostic image with excellent resolution can be taken.

For example, when imaging the heart on the back side of an obstacle through a gap between obstacles such as ribs, if n transmission apertures are set to fit in the gap between obstacles, the obstacle may be affected. In addition, artifacts such as jamming noise and shadow artifacts can be reduced for imaging. In addition, a plane wave beam can be transmitted in a desired set deflection direction by providing a delay time difference in an ultrasonic signal that drives n transducers having a transmission aperture. Therefore, it is possible to set the deflection direction so that a plane wave beam can be transmitted to the diagnostic area located behind the obstacle from an angle avoiding the obstacle, or the plane wave beam is transmitted from a different deflection direction through the gap of the obstacle. As a result, the diagnostic region can be observed from various directions. Furthermore, the effect of artifacts such as speckle noise can be reduced by spatially synthesizing diagnostic image data of diagnostic regions imaged from different directions.

Further, the second aspect of the present embodiment that solves the above-described problems is characterized in that the following configuration is adopted instead of the transmission section and the reception section of the first aspect. That is, the transmission unit provides a delay time difference in driving time for a plurality of n (n is a natural number) transducers corresponding to the transmission aperture set in the ultrasound probe, and is provided at one location in the subject. The ultrasonic wave fronts of the n transmission lines transmitted from the n transducers are aligned at the position of the virtual point sound source set to n, and the n number of the sector areas having the virtual point sound source as a vertex are aligned. The transmission line is formed radially. The reception unit generates a reception beam by performing a focusing process on a reflected echo signal received by a plurality of m (m is a natural number) of the transducers corresponding to a reception aperture set in the ultrasonic probe. The frame data is generated by scanning a plurality of reception lines set based on the n transmission lines.

That is, the second aspect is characterized in that a virtual point sound source is formed at an arbitrary desired position, and n transmission lines are radially formed in the entire sector area having the virtual point sound source as a vertex. Thus, for example, a sector area can be formed on the back side of the obstacle by forming a virtual point sound source at a position near the obstacle and away from or near the obstacle. This diagnostic image can be easily obtained. In addition, when imaging the heart behind an obstacle through a gap between obstacles such as ribs, a virtual point sound source is set between the obstacles to avoid jamming noise. Artifacts such as shadows and shadow artifacts can be reduced, and an ultrasonic image of a diagnostic region on the back side (back side) of an obstacle can be taken.

Similarly to the first aspect, a virtual point sound source can be formed at any plurality of different positions to generate a plurality of diagnostic images. By combining these diagnostic images, speckle noise, etc. The effect of the artifact can be reduced.

According to the present embodiment, it is possible to acquire a diagnostic image of a living tissue located behind an obstacle of ultrasonic propagation at a high frame rate while suppressing artifacts.

An embodiment of an ultrasonic diagnostic apparatus to which the present invention is applied will be described with reference to FIG. As shown in the figure, an ultrasonic diagnostic apparatus 1 includes an ultrasonic probe 2 that is used while being in contact with a subject 13, a transmission beam former 3 that forms a transmission beam to be irradiated into the subject 13, and a transmission beam. The ultrasonic probe 2 is driven in accordance with a signal output from the former 3 to generate a transmission beam, and a pulsar receiver 4 that receives a reflected echo signal received by the ultrasonic probe 2 and an output from the pulsar receiver 4 And a reception beam former 5 that inputs a reflected echo signal to be received and performs reception processing to form a reception beam. The transmission unit of the present invention is configured by the transmission beam former 3 and the pulsar receiver 4, and the reception unit of the present invention is formed by the pulsar receiver 4 and the reception beam former 5.

The reception beam data output from the reception beamformer 5 is input to the space synthesis unit 6. The spatial synthesis unit 6 performs spatial synthesis using frame data composed of received beam data for spatial synthesis stored in the spatial synthesis memory 7. The image processing unit 8 extracts diagnostic information from the frame data synthesized by the space synthesis unit 6, generates a diagnostic image, and displays it on the display unit 9. The space composition unit 6, the space composition memory 7, and the image processing unit 8 form an image configuration unit of the present invention.

The transmission beamformer 3, the reception beamformer 5, the space synthesis unit 6, the image processing unit 8, and the display unit 9 are connected to a control unit 10 and a user interface (UI) 11 via a system bus 12, respectively. Necessary data and control commands can be transmitted and received. The control unit 10 controls the entire ultrasound diagnostic apparatus 1 and also controls the transmission beamformer 3 and the reception beamformer 5 to transmit the transmission beam transmitted to the subject 13 and the reflected echo signal received from the subject 13. A receiving beam is formed. The control unit 10 also controls the transmission beamformer 3 and the reception beamformer 5 to transmit the transmission beam, and scans and receives the reception line set based on the transmission line of the plane wave beam that is the transmission beam. A beam is generated. The user interface (UI) 11 includes an input unit for an operator to operate and operate the ultrasonic diagnostic apparatus 1.

The ultrasonic probe 2 is a phased array, is formed by arranging a plurality of transducers, and has a function of transmitting and receiving ultrasonic waves to and from the subject 13. The pulsar receiver 4 outputs a transmission pulse for driving the ultrasonic probe 2 to generate an ultrasonic wave, and captures a reflected echo signal received by the ultrasonic probe 2 and amplifies it with a predetermined gain. To generate a reception signal.

The transmission beamformer 3 is coupled with the pulsar receiver 4 based on a control command given from the control unit 10 and a plurality of n (n is a natural number) transducers corresponding to the transmission aperture set in the ultrasonic probe 2. Driven to transmit a plane wave beam (transmission beam) composed of n transmission lines in the set deflection direction θ in the subject 13. Here, the set deflection direction θ is expressed as ± θ, where θ = 0 is the deflection direction perpendicular to the ultrasound transmission / reception surface of the ultrasound probe 2 and ± θ is the traveling direction of the plane wave beam deflected symmetrically with reference to this. To do. The transmission beamformer 3 transmits a transmission beam in one or a plurality of set deflection directions θi given from the control unit 10, so that a delay time difference is provided in the ultrasonic signal that drives n transducers, and the set deflection direction A plane wave beam is transmitted to θi so that the wave fronts are aligned.

The reception beamformer 5 is coupled to the pulser receiver 4 by a plurality of m (m is a natural number) transducers corresponding to the reception aperture set in the ultrasonic probe 2 based on a control command given from the control unit 10. A received beam is generated by focusing the reflected echo signal received. In other words, a reflected echo signal is input to perform phasing control, and focus processing is performed on one point or a plurality of convergence points to form a reception beam. At this time, a plurality of reception lines set based on n transmission lines are scanned, and a reception beam is generated for each reception line. Then, frame data composed of a plurality of reception beams obtained by scanning all reception lines is generated. When plane wave beams are transmitted in a plurality of set deflection directions θi, a plurality of reception lines set based on n transmission lines are scanned to generate frame data for each of the plurality of set deflection directions θi. It is like that. The number of reception lines can be set to the same number as the number of transmission lines or a number smaller than the number of transmission lines.

The image processing unit 8 obtains diagnostic image data by applying various filters, detection, reflection intensity image luminance conversion, blood flow velocity calculation, scan conversion processing, image of each mode, character, scale, and other overlays. When a plurality of set deflection directions θ are set, a spatial composite image is generated based on the received beam data for each deflection direction. The display unit 9 displays the diagnostic image data generated by the image processing unit 8 on the screen as a diagnostic image.

The control unit 10 includes a CPU, a main memory, an HDD, and the like, and controls each unit of the ultrasonic diagnostic apparatus 1 via a system bus 12, a serial interface, a network, and the like. That is, the control unit 10 controls the operation of each unit of the ultrasonic diagnostic apparatus 1 in accordance with an instruction according to an operation of the operator input from the user interface 11 connected to the system bus 12. The user interface 11 includes a trackball, a keyboard, a switch, and the like.

The spatial synthesis unit 6 stores the reception beam data of at least one frame in the spatial synthesis memory 7, and receives the reception beam data of the second and subsequent frames and the reception beam data at the corresponding position of the stored frame. The combined reception beam data is generated on a frame basis. A known synthesis method can be applied to the spatial synthesis. For example, a plurality of frames of received beam data are added and averaged in units of pixels to generate synthesized frame data composed of the synthesized received beam data. The image processing unit 8 performs filtering processing, detection processing, reflection intensity image luminance conversion processing, blood flow velocity calculation, scan conversion processing on each combined reception beam data of the combined frame data output from the space combining unit 6 as necessary. , Etc. are performed to generate a desired diagnostic image. That is, a plurality of diagnostic images are generated by the space synthesizing unit 6, the space synthesizing memory 7, and the image processing unit 8 based on received beam data generated for a sector area described later, and the plurality of diagnostic images are synthesized. An image constructing unit for generating the synthesized diagnostic image is formed.

The diagnostic image capturing method of the present invention performed by using the ultrasonic diagnostic apparatus according to the embodiment configured as described above will be described in each example. In the following embodiments, an example will be described in which the number and positions of transmission lines that form a plane wave beam and reception lines that form a reception beam are set to be the same. However, the present invention is not limited to this, and the number of transmission lines and the number of reception lines can be set differently.

(Example 3)
In the third embodiment, description will be made assuming that a diagnostic image of the heart 14 is taken as a diagnostic site in the subject 13 as shown in FIG. As shown in the figure, a rib 15 that is an obstacle is located between the ultrasound probe 2 and the heart 14. When a diagnostic image is captured by sector scanning using a conventional phased array ultrasound probe 2, as shown in FIG. 16, the ultrasound probe is performed with the vertex (scanning center) 16 of the sector area as the sector scanning center. It is set so as to be positioned at the center of arrangement of a plurality of transducers on the ultrasonic transmission / reception surface of the touch element 2. In this case, since an area 18 is formed in which the rib 15 blocks the scanning line 17 that is a transmission / reception line with respect to the heart 14, an image in which a part of the heart 14 is hidden by the acoustic shadow is obtained. Further, as a result of the irregular reflection of ultrasonic waves at the ribs 15, artifacts 119 are generated, which hinders diagnosis.

Therefore, in the third embodiment, as shown in FIGS. 17 (a) to 17 (c), a plurality of parallel transmission / reception lines at the center of the acoustic window which is a gap formed between the two ribs 15a and 15b. A center transmission / reception line 20-c is set at the center in the width direction of the plane wave beam 121 composed of 20. 17A to 17C, center transmission / reception lines 20-c are set at the centers on the line connecting the narrowest points 122a and 122b of the narrowest gap between the two ribs 15a and 15b, respectively. An example is shown. However, the present invention is not limited to this, and the center transmission / reception line 20-c passing through at least one point on the line connecting the narrowest points 122a and 122b is set. The center transmission / reception line 20-c is set, for example, in a preparation stage for acquiring a diagnostic image of the heart 14, for example, a diagnostic region 14 including a rib 15 obtained by bringing the ultrasonic probe 2 into contact with the body surface of the subject 13. This tomographic image is displayed on the display unit 9, and the operator can set the center transmission / reception line 20-c at the center in the width direction of the plane wave beam 121 from the user interface 11 on the tomographic image. Further, as will be described later, the center transmission / reception line 20-c can be automatically set by the control unit 10.

When the center transmission / reception line 20-c is set by the user interface 11, the control unit 10 sets the plane wave beam 121 centered on the set center transmission / reception line 20-c. The plane wave beam 121 is a transmission parameter including a set deflection direction (deflection angle) θ range (+ θ, −θ) of the center transmission / reception line 20-c, a transmission line pitch, the number of transmission lines, a transmission aperture (n), and the like. It is set according to the criteria of transmission conditions set in advance. Then, the control unit 10 controls the transmission beam former 3 in accordance with the set transmission conditions, and transmits a transmission beam to the subject 13 via the pulser receiver 4 and the ultrasonic probe 2. Further, the control unit 10 presets a reception aperture for receiving focus and reception parameters such as a reception line pitch, the number of reception lines, and one or a plurality of focus points based on the number of transmission / reception lines 20. The reception beamformer 5 is set according to the reception condition criteria.

In FIG. 17, for the sake of simplicity, the number of transmission / reception lines 20 of the plane wave beam 121 is shown in plural (three in the illustrated example) in the set deflection direction (three in the illustrated example). The number of 20 can be set to several tens to several hundreds. Also, the number of set deflection directions can be set as appropriate. Received beam data formed by scanning reflected echo signals based on plane wave beams 121 having different deflection angles along the transmission / reception line 20 is stored in the space synthesis memory 7 by the space synthesis unit 6 for each of a plurality of set deflection directions. . Then, the spatial synthesis unit 6 spatially synthesizes the reception beam data in the same space where frame data composed of reception beam data in a plurality of set deflection directions overlaps to generate a synthesized diagnostic image.

In FIG. 18A, n transducers corresponding to the transmission aperture of the ultrasound probe 2 are driven, and a plane wave composed of n transmission / reception lines 20 parallel to the set deflection direction θi in the subject 13. A transmission operation for forming the beam 121 and a reception operation for generating a reception beam by performing a focusing process on a reflected echo signal received by a plurality of m transducers (m is a natural number, m ≦ n) corresponding to the reception aperture. A timing chart is shown. As shown in the figure, the transmission beam former 3 intermittently transmits a plane wave beam composed of ultrasonic transmission pulses over a set time. While the plane wave beam is stopped, the reception beamformer 5 scans the set transmission / reception line 20 while switching the reception aperture to form a reception beam and acquire frame data. This operation is performed for a plurality of set deflection directions θi to obtain frame data for each set deflection direction θi.

Note that, according to the example of FIG. 18A, when the number of transmission / reception lines 20 is large, it may take time to acquire frame data. In this case, as shown in FIG. 18B, if the transmission / reception line 20 is divided into a plurality of N sets in the width direction of the plane wave beam 121, and the transmission / reception lines 20 are scanned in parallel for each divided group, Frame data acquisition time can be shortened. That is, the control unit 10 controls the transmission beam former 3 to transmit the plane wave beam 121 for each set deflection direction θi. Further, the control unit 10 controls the reception beamformer 5 to divide the plurality of transmission / reception lines 20 of the plane wave beam 121 into a plurality of N sets, and scans the transmission / reception lines 20 for each divided group to generate reception beams. . Then, frame data is generated for each set deflection direction θi based on the plurality of generated reception beams. Further, FIGS. 18A and 18B may be appropriately combined.

As described above, according to the diagnostic image capturing method of the third embodiment illustrated in FIG. 17, the center transmission / reception line 20-c of the plane wave beam 121 is set between the ribs 15 that are obstacles, and the plane wave beam 121 is The number and pitch of the transmission / reception lines 20 can be adjusted according to the set deflection direction θ so that the width falls between the ribs 15 as obstacles. Therefore, it is possible to depict the heart 14 which is a diagnostic site without being hidden by the acoustic shadow of the rib 15. Therefore, even if the size of the gap between the ribs 15, the depth from the body surface, and the set deflection direction θ change depending on the position of the ultrasonic probe 2, the width of the plane wave beam 121 is increased correspondingly. Therefore, the transmission / reception line 20 can be captured without being obstructed by the obstacle. Thereby, it is possible to easily acquire diagnostic images viewed from different angles by changing the position of the ultrasound probe 2 in various ways.

Further, since unnecessary irregular reflection by the ribs 15 can be reduced, artifacts such as jamming noise can be reduced. Furthermore, since a plurality of set deflection directions θ can be set and a diagnostic object can be imaged from different deflection directions, frame data consisting of received beam data in those multiple deflection directions is acquired, and these frame data are spatially synthesized to produce a diagnostic image. Therefore, speckle noise can be reduced.

In the third embodiment, the plane wave beam is deflected in three directions. However, the present invention is not limited to this, and the spatial resolution and the contrast resolution can be improved by appropriately increasing according to the allowable imaging time. . In this embodiment, the transmission / reception line 20 has been described with three examples for the sake of simplicity. However, the present invention is not limited to this, and by setting the transmission / reception line 20 according to an allowable imaging time, Contrast resolution can be improved.

In the third embodiment, an example of a plane wave beam for unfocused transmission is shown. However, the present invention is not limited to this, and a relatively weak focused transmission is performed according to the number of transmission / reception lines and the interval between reception beams. This can also be realized by using a plane wave beam composed of a transmission line having a strong pressure. In this case, the weakly focused plane wave beam is adjusted and corrected by reception gain or the like in consideration of sensitivity differences among a plurality of reception beams and the influence of side lobes.

(Modification of Example 3)
In the third embodiment, an example in which the heart that is the diagnostic site 14 is imaged from between the ribs 15 is shown. However, the present invention is not limited to intercostal imaging, and even when there is no influence from an obstacle, by applying the present invention, it is possible to capture a diagnostic image with a high frame rate, excellent spatial resolution, and few artifacts. it can. For example, as shown in FIGS. 19A to 19C, a plurality of sheets (see FIG. 19) with the width of the plane wave beam 121 adjusted to the size of the diagnostic region 14 and the set deflection direction θi are changed. Frame data of 3 frames in the example is acquired. Then, by performing spatial synthesis in the spatial synthesis unit 6 based on a plurality of pieces of frame data, it is possible to capture a diagnostic image with excellent spatial resolution and few artifacts. That is, by adjusting the position and width of the plane wave beam according to the presence / absence of an obstacle and the position of the obstacle, a wide range or a local range according to the range of the diagnostic region 14 or the transmission / reception line 20 The interval can be adjusted freely.

Example 4
A fourth embodiment of the diagnostic image capturing method of the present invention will be described with reference to FIG. In the present embodiment, as in the case of the third embodiment, it is assumed that a diagnostic image of the heart 14 is taken as a diagnostic site in the subject 13. The fourth embodiment is different from the third embodiment in that a gap formed between the two ribs 15a and 15b is used instead of transmitting a plane wave beam 121 including a plurality of parallel transmission / reception lines 20. The purpose is to transmit the virtual point sound source 31 from a plurality of transducers constituting the transmission aperture. That is, after a plurality of transmission / reception lines 32 emitted from the transducer corresponding to the transmission aperture intersect at the virtual point sound source 31, a plane wave beam 33 spreading in a sector shape is formed, and the plane wave beam 33 is propagated by an ultrasonic wave such as a rib. This is because it is not obstructed by other obstacles. In the illustrated example, for the sake of simplicity, three virtual point sound sources 31 are arranged and three transmission / reception lines 32 are shown. However, as in the third embodiment, the present invention is not limited to this. Yes.

Using the user interface 11, as shown in FIGS. 20A to 20C, three virtual point sound sources 31 are set between obstacles (for example, ribs) 15a and 15b. Moreover, the width | variety which arrange | positions the virtual point sound source 31 is naturally set narrower than the space | interval of the obstruction (for example, rib) 15a, b. The control unit 10 controls the transmission beamformer 3 and the reception beamformer 5 based on scanning information such as the number of virtual point sound sources 31, a scanning angle, and a scanning pitch.

The transmission beamformer 3 transmits a plurality of n transducers corresponding to the transmission aperture (transmission sub aperture) D set in the ultrasonic probe 2 with a delay time difference based on a control command to the control unit 10. Drive by pulse. The delay time difference is determined so that the ultrasonic wavefronts of the n transmission / reception lines 32 transmitted from the n transducers are aligned at the position of the virtual point sound source 31. As a result, the energy transmitted from the transmission sub-aperture D is focused on the virtual point sound source 31, and n transmission / reception lines 32 are diffused radially from the virtual point sound source 31 to the entire sector region to form a plane wave beam 33. . Here, in order to form the ideal virtual point sound source 31, the transmission sub aperture D is set as in the following equation (1). In the following equation (1), L is the shortest distance between the transmission / reception surface of the ultrasound probe 2 and the virtual point sound source 31, and θmax is the maximum scanning angle.
D> 2Ltan (θmax) (1)
However, if the transmission sub aperture D is too large, artifacts due to the influence of the obstacle (for example, ribs) 15 increase, and adjustment is necessary.

On the other hand, the reception beamformer 5 is a reflected echo received by a plurality of m (m is a natural number) transducers corresponding to the reception aperture set in the ultrasonic probe 2 based on a control command of the control unit 10. The signal is focused on the transmission / reception line 32 to generate a reception beam. Frame data is generated from received beam data obtained by scanning n transmission / reception lines 32. For example, the received beam data obtained for each of a plurality of set deflection directions is stored in the space synthesizing memory 7 by the space synthesizing unit 6, and the received beam data in the same space is synthesized to generate one synthesized diagnostic image. . According to the spatial synthesis of the fourth embodiment, speckle noise can be reduced as shown in the conceptual diagram of FIG.

According to the fourth embodiment, the virtual point sound source 31 is set between the obstacles (for example, ribs) 15a and 15b, and the diagnostic part 14 transmits and receives ultrasonic waves without being hidden by the acoustic shadow of the obstacle 15. Therefore, it is possible to obtain a diagnostic image in which artifacts such as jamming noise are reduced by reducing unnecessary irregular reflection due to an obstacle. In this embodiment, the case where three virtual point sound sources 31 are set has been described. However, by setting more virtual point sound sources 31, the spatial resolution and the contrast resolution can be improved.

(Modification 1 of Example 4)
In the fourth embodiment, an example is shown in which the diagnostic part 14 on the back side (back side) of the obstacles 15a and 15b is imaged from the gap between the pair of obstacles (for example, ribs) 15a and b. Not limited to this, as shown in FIG. 22, virtual point sound sources 31a, 31b are respectively set in two gaps formed by three obstacles (for example, ribs) 15a, b, c, and the same as in the fourth embodiment. An image can be taken. According to this, it is possible to take an image even in the case of a relatively large diagnostic region 14 and when there are relatively many obstacles 15a to 15c. In addition, since imaging can be performed without being hidden by the acoustic shadows of the plurality of obstacles 15a to 15c, unnecessary irregular reflection due to the obstacles can be reduced, and artifacts such as jamming noise can be reduced.

(Modification 2 of Example 4)
23, the number of transmission / reception lines 32 passing through the virtual point sound source 31 set between the obstacles 15a and 15b is compared with that in FIGS. 23 (a) and 23 (c), as shown in FIG. This can be increased when the point sound source 31 is set at the center position. Thus, when the ultrasonic probe 2 is relatively far from the obstacles 15a and 15b, the image display range can be expanded by increasing the number of transmission / reception lines 32. In this example, the transmission / reception line 32 is set symmetrically, but the display range can be expanded by changing the left / right ratio.

(Modification 3 of Example 4)
FIG. 24 shows an example in which the number of virtual point sound sources 31 is two and the number of transmission / reception lines 32 is increased. As in this example, the effect of spatial synthesis and the density of the transmission / reception line 32 can be adjusted to adjust the effect of improving spatial resolution and the effect of reducing artifacts.

(Modification 4 of Example 4)
FIG. 25 shows an example in which two virtual point sound sources 31 are set in the depth direction. This is effective when the distance between the obstacles 15a and 15b is relatively narrow.

(Modification 5 of Example 4)
FIG. 26 and FIG. 27 show an example in which five virtual point sound sources 31 are set when there is no obstacle. FIG. 26 is an example in which the virtual point sound source 31 is set on the transmission / reception surface of the ultrasonic probe 2, and FIG. 27 is set on the inner side of the ultrasonic probe 2 than the transmission / reception surface of the ultrasonic probe 2. This is an example. Thus, by adjusting the position of the virtual point sound source 31 according to the presence and position of the obstacle, it is possible to freely set a wide range or any local range, or the interval between the transmission and reception lines 32 according to the range of the diagnosis part. It becomes possible to adjust.

Further, in the spatial synthesis in the third and fourth embodiments, among the plurality of transmission / reception lines 20 and 32, the synthesis is performed by multiplying the weighting coefficient at the time of synthesis so that the weight of the spatial data far from the obstacle 15 is increased. be able to. As a weighting factor, it is desirable that the apodization is continuous with respect to the arrangement of the transmission / reception lines 20 and 32 such as Hanning, Hamming, and Blackman. In the third and fourth embodiments, the ultrasonic probe 2 has shown an example in which a plurality of transducers are arranged in a planar shape. However, the present invention is not limited to this, and for example, a plurality of transducers are arranged on a curved surface. The applied ultrasonic probe can be applied. In short, it is only necessary that the receiving line can be deflected by the phase and the delay amount.

As described above, the example in which the rib 15 that is an obstacle is located between the ultrasound probe 2 and the heart 14 that is the diagnostic site (diagnosis region) has been described based on Examples 3 and 4. The invention is not limited to this. That is, even when there is only one obstacle for sound wave propagation and the diagnosis part extends to the back side of the obstacle, the transmission beam and the reception beam described in the third and fourth embodiments and the modifications thereof are used. It is possible to obtain a diagnostic image in which artifacts caused by reflection of sound waves by obstacles are reduced. That is, the transmission unit transmits a plane wave beam so as to avoid the obstacle of ultrasonic propagation in the subject, and the reception unit receives the reflected echo signal so as to avoid the obstacle of ultrasonic propagation in the subject. By generating the received beam by performing the focusing process, it is possible to capture a diagnostic image of the living tissue with reduced artifacts.

For example, by transmitting a non-focused transmission plane wave beam consisting of n transmission lines from the n transmission apertures into the subject and arbitrarily adjusting the deflection direction of the plane wave beam, the obstacle of ultrasonic propagation is reduced. Avoiding this, the plane wave beam can be irradiated to the diagnostic region located behind the obstacle. Similarly, a diagnostic image of a living tissue with reduced artifacts can be taken by forming a reception beam while avoiding an obstacle in the deflection direction. In addition, since the plane wave beam is transmitted, the ultrasonic wave can be transmitted to the entire diagnosis region by one transmission without scanning. In addition, since time required for scanning is unnecessary, the frame rate can be increased by performing parallel reception.

In addition, a sector area can be formed on the back side of the obstacle by forming a virtual point sound source at a depth near the obstacle and away from or near the obstacle. Can be easily obtained.

(Example 5)
An imaging method of Example 5 using an ultrasonic diagnostic apparatus to which the present invention is applied will be described with reference to FIGS. The fifth embodiment is different from the third and fourth embodiments in that the transmission beam (plane wave beam) is code-modulated and the reception beam is code-demodulated to generate reception beam data. That is, when the plane wave beam 121 is transmitted at the same time in the plurality of setting deflection directions in FIG. 17 of the third embodiment, code modulation and code demodulation are performed so that reception beam data for each of the plurality of setting deflection directions can be identified and acquired. It is in doing so. Since the other points are the same as those of the third and fourth embodiments, the same reference numerals are given and the description thereof is omitted.

FIG. 28 shows a block diagram of an ultrasonic diagnostic apparatus 1 that implements the fifth embodiment. In addition to the ultrasonic diagnostic apparatus 1 of the third embodiment shown in FIG. 15, the transmission modulation unit 41 is provided to code-modulate the plane wave beam signal generated by the transmission beam former 3, and the reception demodulation unit 42 is provided to receive the reception beam. The reception beam signal output from the former 5 is code-demodulated and output to the spatial synthesis unit 6. The transmission modulation unit 41 and the reception demodulation unit 42 are connected to the control unit 10 and the user interface 11 via the system bus 12, respectively.

The transmission modulation unit 41 modulates the transmitted plane wave beam signal using a code coefficient such as Barker, Golay, or Chirp. The reception demodulator 42 demodulates the received beam signal using a code demodulation coefficient corresponding to the code modulated by the transmission modulator 41.

With reference to FIG. 29, the imaging method of the diagnostic image of the present Example 5 is demonstrated. FIG. 29 is characterized in that diagnostic images in a plurality of set deflection directions in the third embodiment shown in FIG. 17 are taken in parallel. This further increases the frame rate and spatially synthesizes diagnostic image data in a plurality of set deflection directions to obtain a diagnostic image with high resolution and reduced artifacts. That is, FIG. 29 is an example in which a diagnostic image of the heart that is the diagnostic region 14 is to be taken through a gap formed between the two ribs 15a and 15b.

In the fifth embodiment, the plane wave beam 121a, deflected in a plurality of (3 in the illustrated example) set deflection directions (+ θ, 0 °, −θ) using the user interface 11 in the gaps between the ribs 15a, b. b and c are transmitted at the same time. The control unit 10 sets parameters for the plane wave beams 121a, 121b, 121c, including the angle of the set deflection direction (+ θ, 0 °, −θ), the transmission / reception line pitch, the number of transmission / reception lines, the transmission / reception aperture, etc. And the transmission beamformer 3 and the reception beamformer 5 are controlled. That is, the transmission beamformer 3 transmits plane wave beams 121a, 121b, and 121c having different deflection directions at the same time. On the other hand, the reception beamformer 5 scans the transmission / reception lines 20 of the plane wave beams 121a, 121b, and 121c, and acquires the reception beam data of the reflected echo signal. The received beam data acquired for the plane wave beams 121a, 121b, and 121c is stored in the space synthesis memory 7 by the space synthesis unit 6 and is spatially synthesized as in the third embodiment. However, since plane wave beams deflected in three set deflection directions (+ θ, 0 °, −θ) are mixed in the same sector region, contamination thereof must be avoided.

Therefore, in the fifth embodiment, the three plane wave beams 121a, 121b, 121c are subjected to different code modulations and transmitted. The reception beam generated on the transmission / reception lines 20a, b, c of the plane wave beams 121a, 121b, 121c is code-demodulated with a code corresponding to the code modulation of the plane wave beams 121a, 121b, 121c. Thereby, since the plane wave beam (transmission beam) and the reception beam can be associated with each other, the transmission beam and the reception beam corresponding to the three set deflection directions can be separated, and contamination thereof can be prevented.

FIG. 30 shows a configuration diagram of the transmission modulation unit 41 of the fifth embodiment. The transmission modulation unit 41 includes a fundamental wave storage unit 43 that stores a fundamental wave of a transmission signal configured by a memory such as a RAM, a code modulation coefficient storage unit 44 that stores a code modulation coefficient configured by a memory such as a RAM, a CPU, A fundamental wave formed by a processor such as a DSP or a hard logic such as an FPGA, a convolution operation unit 45 that performs a convolution operation on a code modulation coefficient and generates a code modulation transmission signal, and a code modulation transmission signal that is a result of the convolution operation are stored. It has a code modulation transmission signal storage unit 46 constituted by a memory such as a RAM that outputs to the transmission beamformer 3. The fundamental wave storage unit 43 and the code modulation coefficient storage unit 44 are connected to the control unit 10 via the system bus 12. The outputs of the fundamental wave storage unit 43 and the code modulation coefficient storage unit 44 are connected to the input of the convolution operation unit 45. The output of the convolution operation unit 45 is connected to the input of the code modulation transmission signal storage unit 46. The output of the code modulation transmission signal storage unit 46 is input to the transmission beamformer 3.

The control unit 10 causes the fundamental wave storage unit 43 to store the fundamental wave s of the transmission signal in a predetermined area via the system bus 12. Further, the control unit 10 causes the code modulation coefficient storage unit 44 to store the code modulation coefficient bX in a predetermined area via the system bus 12. The fundamental wave storage unit 43 and the code modulation coefficient storage unit 44 select and read out the storage area of the fundamental wave s and the code modulation coefficient bX, and output them to the convolution calculation unit 45. The convolution operation unit 45 performs a convolution operation process on the input fundamental wave s and code modulation coefficient bX, generates a code modulation transmission signal, and outputs the code modulation transmission signal to the code modulation transmission signal storage unit 46. The code modulation transmission signal storage unit 46 stores the code modulation transmission signal in a predetermined area, reads out the code modulation transmission signal in the predetermined area, and outputs it to the transmission beamformer 3.

FIG. 31 shows an arithmetic expression and waveform of the code modulation transmission signal in the convolution operation unit 45. The code-modulated transmission signal cX can be expressed by the following equation (2) from the fundamental wave s of the transmission signal and the code modulation coefficient bX having a code length (M = 28 in the example). Note that * in the formula represents a convolution operation.
cX = s * bX (2)
Here, different sign-modulated plane wave beams 121a to 121c are transmitted for each set deflection direction (+ θ, 0 °, −θ) in FIG. These code modulation transmission signals cA, cB, and cC can be expressed by the following equation (3), where the code modulation coefficients are bA, bB, and bC.
cA = s * bA
cB = s * bB
cC = s * bC (3)
Here, the fundamental wave s is a sin wave of one wave number, and each code modulation coefficient bA, bB, bC is
bA = [−, +, +, −, +, +, −, +, +, −, +, −, +, −, +, +, +, +, +, +, −, −, −, + , +,-,-,-],
bB = [−, +, +, +, −, −, −, −, +, +, +, −, +, +, +, −, +, +, +, −, +, +, −, + ,-,-, +,-],
bC = [+, −, +, +, −, −, +, −, −, +, −, +, −, +, +, +, +, +, +, +, −, −, −, + , +, +, −, −], And the code “+” is phase 0 ° and the code “−” is phase 180 °, the code modulation transmission signals cA, cB having the waveforms shown in FIG. cC is generated.

Code modulation applied to each transducer ch01 to ch38 when the number of transducers of the ultrasonic probe 2 is 38 and plane wave beams 121a to 121c are transmitted simultaneously in the deflection direction (+ θ, 0 °, −θ) The time waveform of the transmission signal is shown in FIG. In the figure, a slower time is shown as it goes to the right. FIG. 33 shows a schematic diagram of the sound field distribution of the ultrasonic wave transmitted from the ultrasonic probe 2. In the figure, it shows that the depth is deeper than the ultrasonic probe 2 as it goes to the right. As shown in FIG. 33, the ultrasonic probe 2 having the transducers ch01 to ch38, the obstacle 15a, and the obstacle 15b are located. Here, the position of the center transmission / reception line 20-c of the plane wave beam 121 b is arranged at the center of the plane wave beam 121 b on the user interface 11. Next, the control unit 10 determines the position of the center transmission / reception line 20-c, the deflection direction (+ θ, 0 °, −θ) of the plane wave beams 121a to 121c, the transmission aperture D, 12ch in this example, and the plane wave beams 121a to 121c. The transmission aperture diameter D: ch04 to ch15, ch14 to ch25, ch24 to ch35) is set for each of the deflection directions (+ θ, 0 °, −θ), and the delay amount of each channel of the plane wave beams 121a and 121c is calculated. To control the transmission beamformer 3. Here, the transmission aperture D is calculated based on the transmission frequency, the deflection direction, and the transducer pitch so that the plane wave beams 121a to 121c are within the distance between the obstacles so as not to be affected by the obstacles 15a and 15b. . The delay amount for deflecting the plane wave beams 121a and 121c is calculated from each transducer within the transmission aperture D, the deflection direction (+ θ, −θ), and the sound velocity of the subject 13.

32, in the plane wave beam 121c, the code modulation transmission signal cC subjected to delay processing is applied so that ch35 is driven earliest and ch24 is driven latest. In the plane wave beam 121b, the same delay-modulated code-modulated transmission signal cB is applied from ch14 to ch25. In the plane wave beam 121a, the code-modulated transmission signal cA subjected to delay processing is applied so that ch04 is driven earliest and ch15 is driven latest. As a result, as shown in FIG. 33, the ultrasonic signal transmitted from the transmission aperture of the plane wave beam 121c forms a wavefront deflected in the deflection direction −θ, passes through the obstacles 15a and 15b, and the subject. 13 is propagated. Further, the ultrasonic signal transmitted from the transmission aperture of the plane wave beam 121b forms a wavefront in the deflection direction of 0 °, passes through the obstacles 15a and 15b, and propagates through the subject 13. Further, the ultrasonic signal transmitted from the transmission aperture of the plane wave beam 121a forms a wavefront deflected in the deflection direction + θ, passes through the obstacles 15a and 15b, and propagates through the subject 13.

The plane wave beams 121a to 121c having the respective transmission apertures are arranged so as to be an intersection at the center between the obstacles 15a and 15b. Note that the propagation is originally in accordance with the directivity characteristics of each vibration element, but in FIG. 33, in order to easily understand that plane wave transmission is performed, diffusion and display of a wavefront propagating in another direction are omitted.

FIG. 34 shows a specific configuration diagram of the reception beamformer 5 and the reception demodulation unit 42 of the fifth embodiment. The present embodiment is a reception beam former 5 and a reception demodulation unit 42 when applied to plane wave beams 121a to 121c having a plurality of set deflection directions (three directions in the illustrated example). The reception beamformer 5 is configured by a processor such as a CPU or DSP, or a hard logic such as an FPGA. And the delay amount memory | storage part 47 comprised with memories, such as RAM which memorize | stores the delay amount of the received signal of the vibrator | oscillator corresponding to the receiving aperture of the ultrasound probe 2, is provided. In addition, for each transmission aperture of the transducer of the ultrasound probe 2, a delay unit 48 (-1 to 3) for delaying the reception signal of each transmission / reception line and a phasing addition unit 49 (-1 to 3) are provided. There are as many as the number of set deflection directions.

The reception demodulation unit 42 is configured by a memory such as a RAM, and is configured by a code demodulation coefficient storage unit 50 that stores a code demodulation coefficient corresponding to a code modulation transmission signal, a processor such as a CPU or DSP, or a hard logic such as an FPGA. . A convolution operation unit 51 (−1 to 3) is provided which performs a convolution operation by combining the output signal of the reception beamformer 5 and the code demodulation coefficient in three directions and three in parallel. The delay amount storage unit 47 and the code demodulation coefficient storage unit 50 are connected to the control unit 10 via the system bus 12. The output of the delay amount storage unit 47 is connected to the input of the delay unit 48. The output of the pulser receiver 4 is connected to the input of the delay unit 48. The output of the delay unit 48 and the input of the phasing addition unit 49 are connected. The output of the phasing addition unit 49 and the output of the code demodulation coefficient storage unit 50 are connected to the input of the convolution operation unit 51. The output of the convolution operation unit 51 is connected to the input of the space synthesis unit 6.

With this configuration, according to the fifth embodiment, the control unit 10 causes the delay amount storage unit 47 to correspond to the three-direction plane wave beams via the system bus 12 and correspond to the three reception apertures. The delay amounts ΔtA (ch), ΔtB (ch), and ΔtC (ch) to be stored are stored in a predetermined area. In addition, the control unit 10 transmits the code demodulation coefficients b′A, b′B, and b′C corresponding to the code modulation transmission signal of the plane wave beam in the three directions to the code demodulation coefficient storage unit 50 via the system bus 12. Each is stored in a predetermined area. Then, the delay amount storage unit 47 selects and reads out the area of the stored delay amount, and corresponds the delay amount ΔtA (ch) corresponding to the first reception aperture to the delay unit 48-1 and to the second reception aperture. The delay amount ΔtB (ch) to be output is output to the delay unit 48-2, and the delay amount ΔtC (ch) corresponding to the third reception aperture is output to the delay unit 48-3.

The delay units 48-1 to 48-3 perform a time delay corresponding to the input delay amount on the output of the pulsar receiver 4, and output to the phasing adders 49-1 to 49-3. The phasing addition units 49-1 to 4-3 perform addition processing on the reception signals of the respective reception apertures to generate phasing addition signals rbA, rbB, and rbC, and the convolution calculation units 51-1 to 5-3 of the reception demodulation unit 42. Output to. The code demodulation coefficient storage unit 26 selects and reads an area of the code demodulation coefficient stored as appropriate, reads the code demodulation coefficient b′A corresponding to the first reception aperture, and the code demodulation coefficient b ′ corresponding to the second reception aperture. B, the code demodulation coefficient b′C corresponding to the third reception aperture diameter, respectively, the first reception aperture convolution operation unit 51-1, the second reception aperture convolution operation unit 51-2, the third reception aperture convolution operation, respectively. To the unit 51-3.

The first reception aperture convolution operation section 51-1 performs a convolution operation of the phasing addition signal rbA and the code demodulation coefficient b'A corresponding to the first reception aperture, and generates a code demodulated reception signal rA. The second reception aperture convolution operation unit 51-2 performs a convolution operation of the phasing addition signal rbB and the code demodulation coefficient b'B corresponding to the first reception aperture to generate a code demodulated reception signal rB. The third reception aperture convolution operation unit 51-3 performs a convolution operation of the phasing addition signal rbC and the code demodulation coefficient b'C corresponding to the first reception aperture, and generates a code demodulated reception signal rC. Code demodulated reception signals rA, rB, rC corresponding to the respective reception apertures are output to the space synthesis unit 6.

FIG. 35 shows an arithmetic expression and waveform of the code demodulated reception signal. As shown in the figure, assuming that the phasing addition signal rbX and the code demodulation coefficient b′X of a certain number of code demodulation coefficients (N = 57 in the illustrated example), the code demodulation reception signal rX can be expressed by the following equation (4). .
rX = rbX * b′X (4)
Here, three code-modulated ultrasonic waves that differ for each of the three directions (+ θ, 0 °, −θ) in FIG. 29 are transmitted. Also, assuming that each code demodulation coefficient b′A, b′B, b′C, rA, rB, rC can be expressed by the following equation (5).
rA = rbA * b′A
rB = rbB * b'B
rC = rbC * b′C (5)
Here, the code demodulation coefficient is a coefficient of a time inverse filter corresponding to the code modulation coefficient or a mismatch filter coefficient, and is paired so that an error due to the ultrasonic modulation demodulation process becomes very small.

The signal-to-error ratio in the case of the mismatch filter coefficient (N = 57) for the code modulation (M = 28) shown in FIG. 31 of the fifth embodiment is about 30 dB or more. Further, a signal-to-error ratio of about 60 dB or more can be realized in the case of the number of code demodulation coefficients (N = 309). Thus, the signal to error ratio can be improved by increasing the operation scale.

(Example 6)
FIG. 36 and FIG. 37 show an imaging method in which code modulation transmission and code demodulation reception are applied to the fourth embodiment of the virtual point sound source of FIG. Two virtual point sound sources 31 are set between the three obstacles 15a to 15c using the user interface 11. The control unit 10 controls the transmission beamformer 3 and the reception beamformer 5 based on information such as the position of the virtual point sound source and the number of transmission / reception lines, the transmission / reception line angle, and the transmission / reception line pitch. With respect to the plurality of transducers of the ultrasonic probe 2, the two transmission apertures have three directions (+ θ, 0 °, −θ) from the virtual point sound source 31 to the transducer array surface of the ultrasonic probe 2. ), The virtual point sound source becomes an ideal point sound source when the length of the side composed of the angle of the maximum + θ and the minimum −θ (2θ in this case) is larger. Here, two-point transmission of the virtual point sound source 31 and, for example, a reception line deflected in three directions are scanned to obtain a reception beam, and six reception beam data are stored in the space synthesis memory 7 by the space synthesis unit 6. To synthesize data in the same space.

According to this embodiment, when the number of transducers of the ultrasonic probe 2 is 38, two virtual point sound sources 31 are set and applied to the transducers ch01 to ch38 when transmitting ultrasonic waves at the same time. FIG. 36 shows a time waveform of the code modulation transmission signal. In the figure, a slower time is shown as it goes to the right. FIG. 37 shows a schematic diagram of the sound field distribution of the plane wave beam transmitted from the ultrasound probe 2. Similarly, the farther the distance from the ultrasound probe 2 is, the closer to the right. The control unit 10 sets the position of the virtual point sound source 31 and the deflection direction (+ θ, 0 °, −θ) of plane wave transmission. In this example, the transmission apertures ch04 to ch23 are assigned to the virtual point sound source 31a, and the transmission apertures ch16 to ch35 are assigned to the virtual point sound source 31b. Further, the transmission beam former 3 is controlled by calculating the delay amount for each channel. The delay amount for the virtual point sound source 31 is calculated from the position of each transducer and the virtual point sound source 31 in the transmission aperture and the sound speed of the subject 13.

As shown in FIG. 36, in the transmission apertures ch04 to ch23, the code-modulated transmission signal cA subjected to the delay processing is applied, with ch04 and ch23 being the earliest and ch13 and ch14 being the latest. In addition, in the transmission apertures ch16 to ch35, the code-modulated transmission signal cB subjected to delay processing is applied, with ch16 and ch35 being the earliest and ch25 and ch26 being the latest. As a result, as shown in FIG. 37, a transmission beam transmitted from the transmission apertures ch04 to ch23 forms a wavefront that converges on the virtual point sound source 31a, passes between the obstacles 15a and 15b, and passes through the subject 13. Propagate to. Further, the transmission beam transmitted from the transmission apertures ch16 to ch35 forms a wavefront that converges on the virtual point sound source 31b, passes between the obstacles 15b and 15c, and propagates to the subject 13. Originally, propagation is performed based on the directivity characteristics of each vibration element. However, in FIG. 37, in order to easily understand that the transmission signal is phased and the virtual point sound source is transmitted, diffusion and wavefronts propagating in other directions are transmitted. The display is omitted.

The reception beam former 5 that forms a focused reception beam and the reception demodulation unit 42 that performs code demodulation of the focused reception beam signal can be processed in parallel as described with reference to FIG. The arithmetic processing is changed by a program when it is configured by a CPU or DSP, and when it is configured by an FPGA, the processing content is changed by reconfiguration. Since the operation and effect are the same as described above, the explanation is omitted.

According to the sixth embodiment, since two virtual point sound sources 31 are set between the obstacles 15a to 15c, a plane wave beam is transmitted, and a reception beam can be acquired in parallel for each reception line. The region 14 can be depicted without being hidden by the acoustic shadow caused by the obstacle 15. As a result, unnecessary irregular reflection due to the obstacle 15 can be reduced, and artifacts such as jamming noise can be reduced.

In the sixth embodiment, the case where two virtual point sound sources 31 are set has been described. For example, the spatial resolution and contrast resolution can be improved by increasing the number to three or more, transmitting and receiving ultrasonic waves, and spatially synthesizing. . In the sixth embodiment, the number of scans for parallel reception has been described as three. For example, the spatial resolution and the contrast resolution can be improved by further increasing the number of scans.

According to the present embodiment, by processing each transmission / reception aperture, transmission / reception phasing, and code modulation / demodulation for each virtual point sound source 31, it is possible to generate spatial data that separates mutual information and prevents contamination. Since the frame rate can be increased, an optimal diagnostic image state can be obtained.

DESCRIPTION OF SYMBOLS 1 Ultrasonic diagnostic apparatus 2 Ultrasonic probe 3 Transmission beam former 4 Pulsar receiver 5 Reception beam former 6 Spatial composition part 7 Spatial composition memory 8 Image processing part 9 Display part 10 Control part 11 User interface 12 System bus 13 Subject 21 transmission modulation unit 22 reception demodulation unit 41 transmission modulation unit 42 reception demodulation unit 43 fundamental wave storage unit 44 code modulation coefficient storage unit 45 calculation unit 46 code modulation transmission signal storage unit

Claims (22)

1. An ultrasonic probe that is used in contact with a subject, and a reflected echo received by the ultrasonic probe while generating the transmission beam for driving the ultrasonic probe and irradiating the subject. A transmission / reception unit that receives a signal and generates a reception beam; a control unit that controls the transmission / reception unit so that the diagnostic region in the subject is sector-scanned using the transmission beam and the reception beam as scanning lines; and An image constructing unit that generates a diagnostic image based on the received beam generated by scanning by a transmitting and receiving unit; and a display unit that displays the diagnostic image;
   Based on the tomographic image of the diagnostic part generated by the image construction unit, the fan-shaped scanning scan of the fan-shaped scanning range is performed so that the fan-shaped scanning range extends to the diagnostic part on the back side of the obstacle that becomes the transmission obstacle of the transmission beam. A scanning center setting unit for setting at least one with the center positioned;
   The ultrasonic diagnostic apparatus, wherein the control unit sets a scanning condition of the sector scan so as to pass through the set scanning center, and controls the transmission / reception unit according to the scanning condition.
2. 2. The ultrasonic diagnosis according to claim 1, wherein the scan center setting unit sets the scan center at a position where a fan scan line at one end of the fan scan range is not obstructed by the obstacle. apparatus.
3. The ultrasonic diagnostic apparatus according to claim 2, wherein the scanning center setting unit sets the scanning center in a spatial region on a side surface of the obstacle viewed from the ultrasonic probe.
4. 2. The super center according to claim 1, wherein when there are a plurality of obstacles, the scan center setting unit sets at least one scan center of the sector scan in a gap between the plurality of obstacles. Ultrasonic diagnostic equipment.
5. The scan center setting unit sets a plurality of the scan centers,
   The control unit is configured to set a plurality of fan-shaped scanning conditions so as to pass through the plurality of set scanning centers, and to control the transmission / reception unit according to the scanning conditions,
   The ultrasonic diagnostic apparatus according to claim 1, wherein the image configuration unit generates the diagnostic image by combining a plurality of the diagnostic images generated for each scanning center.
6. 2. The ultrasonic diagnostic apparatus according to claim 1, wherein a plurality of the scanning centers exist with respect to an ultrasonic radiation surface of the ultrasonic probe.
7. The ultrasonic diagnostic apparatus according to claim 6, wherein a plurality of the scanning centers exist perpendicularly to an ultrasonic radiation surface of the ultrasonic probe.
8. The scanning center is set to a space defined by a straight line connecting the obstacles adjacent to the ultrasonic radiation surface of the ultrasonic probe and the ultrasonic radiation surface of the ultrasonic probe. The ultrasonic diagnostic apparatus according to claim 1.
9. The transmission / reception unit modulates the transmission beam of the scanning line passing through the scanning center for each scanning center with a different modulation code and the demodulation set for the reception beam of the scanning line corresponding to the modulation code The ultrasonic diagnostic apparatus according to claim 1, wherein demodulation is performed using a code.
10. An ultrasonic probe used in contact with a subject, a transmitter for transmitting an ultrasonic signal that drives a plurality of transducers of the ultrasonic probe, and a plurality of transducers of the ultrasonic probe A receiving unit that receives and processes the reflected echo signal received by the image processing unit, an image configuration unit that generates a diagnostic image based on the received signal that has been received and processed by the receiving unit, a display unit that displays the diagnostic image, and at least the A control unit that controls the transmission unit, the reception unit, and the image configuration unit; and an input unit that inputs a command to the control unit;
    The transmission unit drives a plurality of n (n is a natural number) of the transducers corresponding to a transmission aperture set in the ultrasound probe, and n transmission lines in a set deflection direction in the subject. A plane wave beam consisting of
    The reception unit generates a reception beam by performing a focusing process on a reflected echo signal received by a plurality of m (m is a natural number) of the transducer corresponding to a reception aperture set in the ultrasonic probe, Generating frame data composed of a plurality of reception beams obtained by scanning a plurality of reception lines set based on the n transmission lines;
    The ultrasonic diagnostic apparatus, wherein the image construction unit generates the diagnostic image based on the frame data generated by the receiving unit.
11. The transmitting unit transmits the plane wave beam in the set deflection direction by providing a delay time difference to the ultrasonic signals that drive the n transducers, and at least in a plurality of different set deflection directions based on the control command. Transmitting the plane wave beam each consisting of the n transmission lines,
    The reception unit scans the plurality of reception lines set based on the n transmission lines of the plane wave beam transmitted in the plurality of setting deflection directions, and the frame data for each of the plurality of setting deflection directions. Produces
    The ultrasonic diagnostic apparatus according to claim 10, wherein the image configuration unit generates the diagnostic image by combining frame data for each of the plurality of setting deflection directions.
12. The control unit controls the transmission unit to transmit the plane wave beam for each of the set deflection directions, and controls the reception unit to set a plurality of transmission lines of the plane wave beam in the width direction by N (N is a natural number). ), Sets the plurality of reception lines for each of the divided sets, generates the reception beam, and generates the frame data for each set deflection direction based on the generated plurality of the reception beams. The ultrasonic diagnostic apparatus according to claim 10.
13. The control unit sets a width of a plane wave beam formed from n transmission lines in the set deflection direction to a width that fits in a gap between a plurality of obstacles that are obstacles to propagation of the plane wave beam. The ultrasonic diagnostic apparatus according to claim 12.
14. The control unit aligns the center of a gap between a plurality of obstacles that are obstacles to propagation of the plane wave beam with the center of the plane wave beam width of the n transmission lines, and the plane wave beam width and the n The ultrasonic diagnostic apparatus according to claim 13, wherein a pitch and the number of the reception lines are set.
15. The transmitting unit modulates the ultrasonic wave of the plane wave beam transmitted in the plurality of setting deflection directions with a different modulation code for each of the setting deflection directions,
    The ultrasonic diagnostic apparatus according to claim 11, wherein the reception unit demodulates the reception beam of the reception line corresponding to the set deflection direction with a demodulation code set corresponding to the modulation code. .
16. An ultrasonic probe used in contact with a subject, a transmission unit that transmits ultrasonic signals to a plurality of transducers of the ultrasonic probe, and reception by a plurality of transducers of the ultrasonic probe A reception unit that receives and processes the reflected echo signal, an image configuration unit that generates a diagnostic image based on the reception signal received and processed by the reception unit, a display unit that displays the diagnostic image, and at least the transmission unit A control unit that controls the reception unit and the image configuration unit, and an input unit that inputs a command to the control unit,
    The transmission unit provides a delay time difference in driving a plurality of n (n is a natural number) transducers corresponding to a transmission aperture set in the ultrasound probe, and a virtual set in the subject. The wavefronts of the n transmission lines transmitted from the n transducers at the position of the point sound source are aligned, and the n transmission lines are diffused throughout the sector area having the virtual point sound source as a vertex. Configured to let
    The reception unit receives a reflected echo signal received by a plurality of m (m is a natural number, m ≦ n) corresponding to a reception aperture set in the ultrasonic probe by performing focus processing. Generating a beam and scanning a plurality of reception lines set based on the n transmission lines to generate frame data;
    The ultrasonic diagnostic apparatus, wherein the image construction unit generates the diagnostic image based on the frame data generated by the receiving unit.
17. The ultrasonic diagnostic apparatus according to claim 16, wherein the control unit sets one or a plurality of the virtual point sound sources at arbitrary positions in a deflection direction or a depth direction.
18. The control unit controls the transmission unit to set one or a plurality of the virtual point sound sources, causes each of the set virtual point sound sources to transmit ultrasonic waves to the n transmission lines, and controls the reception unit. Then, the n transmission lines are divided into a plurality of N (N is a natural number) groups, and the reception beams are generated by setting the plurality of reception lines for each of the divided groups. The ultrasonic diagnostic apparatus according to claim 16, wherein the frame data is generated for each virtual point sound source based on a beam.
19. 19. The ultrasonic diagnostic apparatus according to claim 18, wherein the control unit sets the position of the virtual point sound source in a gap sandwiched between a plurality of obstacles that are obstacles to propagation of the ultrasonic wave.
20. The control unit sets the position of the plurality of virtual point sound sources by shifting in the deflection direction or depth direction of the gap between the plurality of obstacles,
    The receiving unit generates the frame data for each of the positions of the plurality of virtual point sound sources set by shifting in the deflection direction or the positions of the plurality of virtual point sound sources set by shifting in the depth direction, thereby generating a diagnostic image The ultrasonic diagnostic apparatus according to claim 19, wherein a plurality of images are picked up.
21. The transmitting unit transmits the plane wave beam so as to avoid an obstacle of ultrasonic propagation in the subject,
    The ultrasonic diagnostic apparatus according to claim 10, wherein the reception unit generates a reception beam by focusing the reflected echo signal so as to avoid an obstacle of ultrasonic propagation in the subject.
22. The transmission unit modulates ultrasonic waves to be transmitted for each position of the plurality of virtual point sound sources with different modulation codes,
    18. The reception unit according to claim 17, wherein the reception unit demodulates the reception beams of a plurality of reception lines set based on the n transmission lines with a demodulation code set corresponding to the modulation code. The ultrasonic diagnostic apparatus as described.

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