JP2004201864A - Ultrasonic imaging device and the ultrasonic imaging method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ultrasonic imaging device or the like which can efficiently obtain an ultrasonic image of a good quality wherein effects by crosstalk are reduced. <P>SOLUTION: This ultrasonic imaging device has a probe 10 for ultrasonic waves including a plurality of ultrasonic transducers which act respectively conforming to a plurality of driving signals, and at the same time, outputs detection signals when receiving an ultrasonic wave, and a crosstalk judging unit 23 which grasps the location of a reflection source existing in a subject based on a detection signal obtained by pre-imaging, and at the same time, judges whether crosstalk is generated or not between a plurality of ultrasonic echoes. The ultrasonic imaging device also has a transmitting/receiving method setting unit 24 which sets a transmitting/receiving method to be used when respective ones of a plurality of imaging regions included in the subject are scanned based on the judgement result by the crosstalk judging unit, a firing timing controller 25 which provides a delay to a plurality of the driving signals conforming to the set transmitting/receiving method, and a phase matching/operation unit 22 which processes the detection signal according to the set transmitting/receiving method. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an ultrasonic imaging apparatus and an ultrasonic imaging method used for performing diagnosis and non-destructive inspection of an in vivo organ by transmitting and receiving ultrasonic waves.
[0002]
[Prior art]
In an ultrasonic imaging apparatus used as a medical ultrasonic diagnostic apparatus or an industrial flaw detection apparatus, an ultrasonic probe (probe) including a plurality of ultrasonic transducers having an ultrasonic transmission / reception function is usually used. Used. By using such an ultrasonic probe, the subject is scanned with an ultrasonic beam formed by combining ultrasonic waves transmitted from a plurality of ultrasonic transducers, so that image information about the subject is obtained. can get. Furthermore, an ultrasonic image in a two-dimensional or three-dimensional region of the subject is reproduced based on this image information. As one of scanning methods using such an ultrasonic beam, so-called sector scanning is known in which a fan-shaped two-dimensional region of a subject is scanned in an angular direction.
[0003]
Sector scanning was originally developed as a technique for observing the heart from the intercostal space of the human body. In general, in sector scanning, an ultrasonic beam extending in the depth direction of a subject from a transmission point is sequentially transmitted in a fan shape into the subject, and the fan-shaped two-dimensional region of the subject is equalized by this ultrasonic beam. Scanned at an interval angle. Here, at each angle, image information relating to a plurality of sampling points distributed at equal intervals along the ultrasonic beam along the ultrasonic beam is sampled at regular time intervals. A two-dimensional or three-dimensional ultrasound image obtained based on sampled image information is called a tomographic echocardiogram for the heart.
[0004]
In recent years, it has been studied to obtain an ultrasonic image at a higher sampling rate. For example, Non-Patent Document 1 discloses that an ultrasonic echo generated by reflecting one transmission beam on a subject is subjected to reception focus so as to form a plurality of reception focal points. It is described that image information relating to a plurality of positions of a subject is obtained by transmission and reception. However, in this case, there is a problem that the spatial resolution is lowered because an ultrasonic beam having a larger diameter must be transmitted as compared with the case of forming one reception focus. Therefore, such a transmission / reception method cannot be applied when obtaining detailed image information in detail.
[0005]
Patent Document 1 discloses crosstalk in an ultrasonic imaging system that uses a two-dimensional transducer array to form a three-dimensional ultrasonic image in real time and simultaneously transmits and receives a plurality of ultrasonic beams. Several techniques for removing are disclosed. As a technique for removing the crosstalk, the ultrasonic beam is encoded and transmitted, the main beam is transmitted in a direction in which the side lobe of the adjacent beam becomes zero, the transmission direction of the ultrasonic beam is separated, or a plurality of The use of different center frequencies between the ultrasound beams is mentioned.
[0006]
However, even if the ultrasonic beam is coded, if the number of ultrasonic beams simultaneously transmitted and received increases, it becomes difficult to identify the ultrasonic beam by the code. Further, even if the main beam is transmitted in a direction in which the side lobe of the adjacent beam becomes zero, the side lobe of the adjacent beam is not completely zero in the living body. On the other hand, when separating the transmission direction of the ultrasonic beam, it is difficult to simultaneously transmit and receive many ultrasonic beams. In addition, when using different center frequencies among a plurality of ultrasonic beams, the frequency band of the ultrasonic transducer is limited, and thus the number of ultrasonic beams that are simultaneously transmitted and received is limited.
[0007]
[Patent Document 1]
US Pat. No. 6,179,780 (abstract, FIGS. 7-10)
[Non-Patent Document 1]
David David, Jensen, Smith, “TWO-DIMENSIONAL RANDOM ARRAYS FOR REAL TIME VOLUMETRIC IMAGING”, Ultrasound Image (ULTRASONIC) IMAGING) 16, p. 143-163, (1994)
[0008]
[Problems to be solved by the invention]
In view of the above, an object of the present invention is to provide an ultrasonic imaging apparatus and an ultrasonic imaging method capable of efficiently obtaining a high-quality ultrasonic image in which the influence of crosstalk is reduced.
[0009]
[Means for Solving the Problems]
In order to solve the above-described problems, an ultrasonic imaging apparatus according to the present invention forms an ultrasonic beam by a plurality of ultrasonic transducers that operate according to a plurality of drive signals, transmits the ultrasonic beam to a subject, and reflects from the subject. The position of the reflection source existing in the subject is grasped based on the ultrasonic probe that receives the ultrasonic echo to be detected and the detection signal obtained in advance, and each of the different reflection sources A determination unit that determines whether there are reflection sources that interfere with each other when a plurality of ultrasonic echoes generated by reflection are received by the ultrasonic probe, and a determination result of the determination unit Based on this, a transmission / reception method setting means for selecting and setting a transmission / reception method used when scanning the imaging region from among a plurality of transmission / reception methods for each of the plurality of imaging regions included in the subject. In accordance with the transmission / reception method set by the transmission / reception method setting means, by delaying a plurality of drive signals supplied to the ultrasonic probe, one or more ultrasonic signals transmitted from the ultrasonic probe are transmitted. A transmission-side signal processing unit that scans a subject with a sound beam, and a plurality of detection signals obtained by reception of ultrasonic echoes according to the transmission / reception method set by the transmission / reception method setting unit, Receiving-side signal processing means for obtaining image information.
[0010]
The ultrasonic imaging method according to the present invention also forms an ultrasonic beam by a plurality of ultrasonic transducers that operate according to a plurality of drive signals, transmits the ultrasonic beam to the subject, and transmits an ultrasonic echo reflected from the subject. An ultrasonic imaging method for imaging a subject using an ultrasonic probe to receive, wherein the subject is scanned by at least one ultrasonic beam to perform pre-imaging step (a); Based on the result of the pre-imaging performed in step (a), the position of the reflection source existing in the subject is grasped, and a plurality of ultrasonic echoes respectively reflected by a plurality of different reflection sources are super Step (b) for determining whether or not there are reflection sources that interfere with each other when received by the acoustic wave probe, and based on the determination result in step (b) (C) selecting and setting a transmission / reception method used when scanning the imaging region from among a plurality of transmission / reception methods for each of a plurality of imaging regions included in the subject; and step (c) In accordance with the transmission / reception method set in (1), the delay is applied to the plurality of drive signals supplied to the ultrasonic probe, so that the one or more ultrasonic beams transmitted from the ultrasonic probe are covered. A step of scanning the specimen (d) and a step of obtaining image information relating to the subject by processing a plurality of detection signals obtained by reception of the ultrasonic echo in accordance with the transmission / reception method set in step (c) (E).
[0011]
According to the present invention, since a transmission / reception method is individually set for each of a plurality of imaging regions included in a subject, it is possible to efficiently obtain a high-quality ultrasound image in which the influence of crosstalk is reduced.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The same constituent elements are denoted by the same reference numerals, and the description thereof is omitted.
FIG. 1 is a block diagram showing a configuration of an ultrasonic imaging apparatus according to an embodiment of the present invention. This ultrasonic imaging apparatus is used as, for example, an ultrasonic diagnostic apparatus for medical examination of a human body or an industrial flaw detection apparatus.
As shown in FIG. 1, this ultrasonic imaging apparatus has an ultrasonic probe 10 used in contact with a subject. The ultrasonic probe 10 has a plurality (N × N = N) having an ultrasonic transmission / reception function. ² This is a so-called two-dimensional transducer array including a plurality of ultrasonic transducers 11. In the ultrasonic probe 10, a plurality of ultrasonic transducers 11 are arranged in a two-dimensional matrix of N rows and N columns, for example. As the ultrasonic transducer 11, for example, a piezoelectric material made of a ceramic piezoelectric material such as PZT (Pb (lead) zirconate titanate) or a polymeric piezoelectric material such as PVDF (polyvinyl difluoride) is used. An element is used.
[0013]
In the present embodiment, one ultrasonic transducer is used for both transmission and reception of ultrasonic waves. However, separate ultrasonic transducers may be provided for transmission and reception of ultrasonic waves. For example, the piezoelectric element is used as an ultrasonic transmission element, and a Fabry-Perot resonator (abbreviated as FPR) or a fiber Bragg grating formed at the tip of a fine optical fiber is used as an ultrasonic reception element. The ultrasonic probe 10 may be configured by combining these. In the present embodiment, a two-dimensional transducer array is used, but in addition to this, a one-dimensional or 1.5-dimensional transducer array may be used.
[0014]
N ² Each ultrasonic transducer 11 includes N ² Each pulser circuit 12 and receiver 14 are connected.
Each pulser circuit 12 excites based on the output signal of the ignition timing controller 25 and outputs a drive signal to the corresponding ultrasonic transducer 11 of the ultrasonic probe 10. Each ultrasonic transducer 11 transmits an ultrasonic pulse to the subject based on the drive signal input from the pulsar circuit 12, receives the ultrasonic pulse reflected from the subject, and outputs a detection signal. As these pulser circuits, it is desirable to use a high-speed pulser circuit that can continuously output a drive signal at a high repetition period (for example, 3 MHz to 10 MHz).
[0015]
Each receiver 14 includes a preamplifier 15, a TGC (time gain compensation) amplifier 16, and an A / D converter 17. The detection signal output from each ultrasonic transducer 11 is subjected to analog processing in the preamplifier 15 and the TGC amplifier 16 included in the corresponding receiver 14. By this analog processing, the levels of these detection signals are matched with the input signal level of the A / D converter 17. The analog signals output from the TGC amplifier 16 are converted into digital signals (data) by the A / D converter 17, respectively.
[0016]
The ultrasonic imaging apparatus includes a system control unit 20, a memory 21, a phase matching calculation unit 22, a display image calculation unit 26, and an ignition timing controller 25. The system control unit 20 controls each unit of the ultrasonic imaging apparatus.
[0017]
Each pulser circuit 12 is connected to the ignition timing controller 25. The ignition timing controller 25 outputs a signal for exciting each pulser circuit 12. In the present embodiment, the ignition timing controller 25 is configured by an electronic circuit, but may be configured by a pattern generator or the like. The ignition timing for transmitting the ultrasonic beam in a plurality of directions within the arrival time of the echo from the maximum imaging depth of the ultrasonic beam transmitted from the ultrasonic probe 10 by the control of the ignition timing controller 25. Can be managed. In addition, the control of the ignition timing controller 25 makes it possible to transmit an ultrasonic beam having a desired diameter in a desired direction.
[0018]
Each receiver 14 is connected to the memory 21. The memory 21 temporarily stores the detection data output from the A / D converter 17 of each receiver 14.
The phase matching calculation unit 22 performs calculation processing to match the phase of the detection data stored in the memory 21. Although the phase matching calculation unit 22 is shown as one block in FIG. 1, a plurality of systems are provided corresponding to the number of transmission beams or the number of reception focal points formed. Each system of the phase matching operation unit 22 is configured by a shift register delay line, a digital minute delay device, a CPU (central processing unit) and software, or a combination thereof.
[0019]
Here, reception beam forming by the phase matching calculation unit 22 is performed as follows. Each system of the phase matching calculation unit 22 gives a predetermined delay to a series of detection data obtained based on the detection signal output from each ultrasonic transducer 11. As a result, the phases of the plurality of detection data obtained using the plurality of ultrasonic transducers 11 are matched. Further, the phase matching calculation unit 22 digitally adds these detection data. In this way, by using the phase matching calculation unit 22 having a plurality of systems, it is possible to simultaneously achieve reception focus in a plurality of directions within the subject.
[0020]
The display image calculation unit 26 performs detection waveform detection, conversion to image data, predetermined image processing, and scanning format conversion on the data output from the phase matching calculation unit 22. Thereby, the image data in the sound ray data space is converted into image data in the physical space. Further, the display image calculation unit 26 generates voxel data that is data about a certain volume from a plurality of pieces of tomographic data, and performs a calculation for displaying a three-dimensional image.
[0021]
An image display unit 30 is connected to the display image calculation unit 26. The image display unit 30 converts the image data whose scanning format has been converted by the display image calculation unit 26 into analog signals by D / A conversion, and displays an image based on these signals.
[0022]
Furthermore, the ultrasonic imaging apparatus according to the present embodiment is provided with a crosstalk determination unit 23 and a transmission / reception method setting unit 24. The crosstalk determination unit 23 grasps the position of the reflection source existing in the subject based on the obtained image information when pre-imaging is performed by pre-scanning the subject, and in a plurality of different directions. When a plurality of ultrasonic beams are transmitted respectively, it is determined whether or not the ultrasonic echoes received from the respective directions cause crosstalk.
[0023]
The transmission / reception method setting unit 24 divides the subject into a plurality of imaging regions based on the determination result of the crosstalk determination unit 23, and selects an optimal transmission / reception method used when scanning each of these imaging regions. In addition, the transmission / reception method setting unit 24 sets a delay time for the ignition timing controller 25 so that an ultrasonic beam is transmitted according to the selected transmission / reception method when full-scale imaging is performed, and the selection is performed. The delay time is set for the phase matching calculation unit 22 so that the reception beam forming of the ultrasonic echo received according to the transmitted / received scheme is performed.
[0024]
Here, the transmission / reception methods used when scanning the subject performed in the present embodiment include a single beam transmission / reception method, a multi-beam transmission / reception method, and a single beam transmission / multi-beam reception method. 2-4 is a figure for demonstrating these systems. 2 to 4 show a cross section of an ultrasonic probe 10 including a plurality of ultrasonic transducers 11.
[0025]
In the single beam transmission / reception system, as shown in FIG. 2, one ultrasonic beam (transmission beam) TB1 is transmitted in one direction, and one reception focal point FP1 is formed for the received echo signal. This is a method of acquiring image information related to one position by performing reception beam forming. According to this transmission / reception method, it is possible to obtain high-quality image information with high azimuth resolution using an ultrasonic beam with a small diameter. On the other hand, when the subject is scanned over a wide range, there is a disadvantage that it takes a lot of time.
[0026]
As shown in FIG. 3, the multi-beam transmission / reception method transmits a plurality of ultrasonic beams TB2 and TB3 in a plurality of directions simultaneously or substantially simultaneously, and transmits a plurality of received echo signals as transmission beams. This is a method of acquiring image information relating to a plurality of positions by performing reception beam forming so as to form a plurality of reception focal points FP2 and FP3 respectively corresponding to TB2 and TB3. According to this method, it is possible to scan the subject at high speed using an ultrasonic beam having a small diameter, so that it is possible to increase the azimuth resolution and the sampling rate. On the other hand, depending on the arrangement of the reflection sources in the subject, crosstalk may occur between a plurality of echo signals received from different directions. Here, when receiving the ultrasonic echo generated by the reflection of the first ultrasonic beam transmitted in one direction, the second ultrasonic beam transmitted in the other direction is transmitted to the reflection source. Crosstalk becomes a problem when ultrasonic echoes that are reflected are received simultaneously.
[0027]
The single beam transmission / multi-beam reception system transmits a single ultrasonic beam TB4 as shown in FIG. 4A, and a plurality of received echo signals as shown in FIG. 4B. Is received as a plurality of reception beams RB4, RB5, RB6 by performing reception beam forming so as to form a plurality of reception focal points FP4, FP5, FP6. According to this transmission / reception method, image information relating to a plurality of positions can be acquired by one-time transmission / reception of ultrasonic waves, so that the subject can be scanned at high speed. On the other hand, since the diameter of the ultrasonic beam transmitted in this method is defined according to the number of reception focal points formed in reception beam forming, it cannot be made smaller than a predetermined value and the azimuth resolution is increased. I can't. For this reason, this transmission / reception method is not appropriate when scanning a region where the change in reflectance is severe.
[0028]
Next, the operation of the ultrasonic imaging apparatus according to the first embodiment of the present invention will be described with reference to FIGS. 1 and 5 to 9. FIG. 5 is a flowchart showing the operation of the ultrasonic imaging apparatus according to this embodiment.
[0029]
First, in step S1, pre-imaging is performed by pre-scanning the subject. As shown in FIG. 6, prior imaging is performed by scanning a plurality of sector regions constituting a three-dimensional region in the subject by a single beam transmission / reception method. Here, since the pre-imaging may take time, a single beam transmission / reception system is used.
[0030]
As shown in FIG. 1, the plurality of pulsar circuits 12 each output a plurality of drive signals according to the control of the ignition timing controller 25. With these drive signals, the plurality of ultrasonic transducers 11 connected to the plurality of pulser circuits 12 are respectively driven, and a plurality of ultrasonic pulses are transmitted. At that time, N ² An ultrasonic pulse may be transmitted from all of the ultrasonic transducers 11 or these N ² The ultrasonic pulse may be transmitted only to some of them.
[0031]
The plurality of ultrasonic pulses transmitted from the plurality of ultrasonic transducers forms one ultrasonic beam. This transmission beam is reflected by a reflection source existing in the transmission direction and received by the ultrasonic probe 10. The plurality of ultrasonic transducers 11 included in the ultrasonic probe 10 output detection signals based on the received ultrasonic echoes. These detection signals are respectively input to the corresponding receivers 14, subjected to analog processing in the preamplifier 15 and the TGC amplifier 16, and matched with the input signal level of the A / D converter 17. Next, the analog signal output from the TGC amplifier 16 is converted into a digital signal by the A / D converter 17, temporarily stored in the memory 21, and then input to the phase matching calculation unit 22. Further, these detection data are subjected to reception beam forming in the phase matching calculation unit 22 so that the received ultrasonic echoes form a reception focus, and detection data corresponding to the transmission beam is generated.
[0032]
Referring to FIG. 6 again, the ultrasonic imaging apparatus according to this embodiment scans one sector area OAB while changing the transmission direction of the ultrasonic beam in the θ direction. Next, the ultrasonic imaging apparatus according to the present embodiment scans different sector regions while shifting the transmission direction of the ultrasonic beam in the φ direction and changing it in the θ direction again. In this way, as shown in FIG. 6, image information relating to a plurality of sector regions constituting the three-dimensional region of the subject is obtained. These pieces of image information are input to the crosstalk determination unit 23 shown in FIG. In the following, for the sake of simplicity, a case where the sector area OAB is imaged will be described.
[0033]
Next, in step S2, the crosstalk determination unit 23 causes crosstalk between a plurality of received ultrasonic echoes when the multi-beam transmission / reception method is used based on the result of the previous imaging. It is determined whether or not such a reflection source exists.
[0034]
Here, the crosstalk determining unit 23 stores “contribution rate” used when determining crosstalk. As shown in FIG. 7, the contribution rate is a direction TX different from each other in the subject. _A , TX _B , TX _C ,..., Reflection sources OB of equal size and reflectivity _A , OB _B , OB _C , ... each exists in one direction (eg TX _A ) In other directions (eg TX _C ) Indicates the degree to which the ultrasonic echo generated is mixed. In the first place, crosstalk occurs when multiple ultrasound echoes are received from different directions at approximately the same time. The degree of crosstalk and the effect it has on the ultrasound image are affected by the transmission direction of the ultrasound beam. It differs depending on the interval between a plurality of transmitted ultrasonic beams, the size of the reflection source, the reflectance, and the like. Therefore, for example, when the interval between a plurality of ultrasonic beams transmitted in the multi-beam transmission / reception method is Δθ, one direction TX _A To other direction TX away by Δθ _C Contribution rate α _A One direction TX _B To other direction TX away by Δθ _D Contribution rate α _B Are obtained for each direction and used as reference values in actual crosstalk determination. These contribution rates are obtained by computer simulation, and are stored in the crosstalk determination unit 23 in association with each direction of the subject.
[0035]
In addition, in order to change the interval Δθ between a plurality of ultrasonic beams transmitted in the multi-beam transmission / reception method, each direction (for example, TX _A Direction) to multiple other directions (eg, TX _B , TX _C , TX _D ,...) May be determined in advance.
[0036]
Next, based on the image information obtained by the pre-imaging, the crosstalk determination unit 23 uses the RF reception signal waveforms RF1 to RF6 received from the TX1 to TX6 directions, respectively, as shown in FIG. Remember. In FIG. 8A, t ₁ ~ T ₆ Indicates the transmission time when the ultrasonic beam is transmitted in the TX1 to TX6 directions. As a result, as shown in FIG. 8B, the existence ranges of the reflection sources OB1 and OB2 in the sector area OAB are grasped.
[0037]
Next, the crosstalk determination unit 23 creates a composite signal waveform used for determination of crosstalk, using the contribution rate estimated in advance for each observation direction. The composite signal waveform is created by adding the RF reception signal waveform related to the observation direction to the RF reception signal waveform related to the other direction that is simultaneously transmitted in the multi-beam transmission / reception method and the contribution rate integrated.
[0038]
For example, as shown in FIG. 8B, when observing the TX2 direction, the other direction simultaneously transmitted in the multi-beam transmission / reception system is the TX4 direction that is Δθ apart from the TX2 direction. Therefore, the synthesized signal waveform has an RF reception signal RF2 and a contribution rate α in the TX2 direction. ₂ And the RF reception signal waveform RF4 in the TX4 direction, as shown in FIG. 9, the combined signal RF2 + α ₂ × Represented as RF4. The same applies to the other observation directions.
[0039]
Next, the crosstalk determination unit 23 determines crosstalk based on the strength of the combined signal. The criterion for determination is that crosstalk occurs when the strength of the synthesized signal increases by more than twice the signal strength before synthesis, that is, 6 dB or more, at the position of the RF reception signal existing before synthesis. To do. For example, in the case shown in FIG. 9, in the TX2 direction, if ΔRF ≧ 6 dB, it is determined that crosstalk occurs. Further, in the TX5 direction, since ΔRF≈0, it is determined that no crosstalk occurs.
[0040]
Next, in step S3, the transmission / reception method setting unit 24 sets the transmission / reception method for each of a plurality of areas included in the sector area OAB.
As illustrated in FIG. 10, the transmission / reception method setting unit 24 divides the sector area OAB into, for example, the following six imaging areas based on the information input from the crosstalk determination unit 23.
(1) Imaging region OAC in which no reflection source exists
(2) Imaging region OCD including both ends of the reflection source OB1
(3) Imaging region ODE where no reflection source exists
(4) Imaging region OEF including one end of the reflection source OB2
(5) Imaging region OFG including the intermediate portion of the reflection source OB2
(6) Imaging region OGH including the other end of the reflection source OB2
(7) Imaging region OHB where no reflection source exists
Further, the transmission / reception method setting unit 24 applies any one of the transmission / reception methods among the single-beam transmission / reception method, the multi-beam transmission / reception method, and the single-beam transmission / multi-beam reception method to the imaging regions (1) to (7). Set each.
[0041]
In the single beam transmission / reception system, there is a reflection source that causes crosstalk in an adjacent imaging region, and therefore, it is an area where multi-beam transmission cannot be performed. It is set for an area that requires high azimuth resolution, such as being present at a high density. As shown in FIG. 10, in this embodiment, the imaging area OCD and the imaging area OEF correspond. These imaging areas include the ends of the reflection source OB1 or OB2, and if the result of the crosstalk determination is that scanning is performed by the multi-beam transmission / reception method, crosstalk occurs due to the other reflection source. Because.
[0042]
The multi-beam transmission / reception method is set in a region where a high azimuth resolution is required, such as the presence of an edge of the reflection source, and there is no reflection source causing crosstalk in the region to be imaged simultaneously. In the present embodiment, a combination of the imaging area ODE and the imaging area OGH corresponds. This is because the imaging region OGH includes the other end of the reflection source OB2, and thus it is necessary to scan the contour thereof with high density. On the other hand, as shown in FIG. 11, since there is no reflection source in the imaging region ODE, even if the imaging region ODE and the imaging region OGH are scanned in parallel using the two transmission beams TB2 and TB3, crosstalk There is no risk of occurrence.
[0043]
The single beam transmission / multi-beam reception method is set for a region where there is no reflection source or the spatial change of the reflectance is gradual. This is because, according to this method, the azimuth resolution is reduced as compared with the previous two methods, so that it is not suitable for an area that needs to be scanned at a high density. As shown in FIG. 10, in the present embodiment, the imaging region OAC and the imaging region OHB in which no reflection source exists, and the imaging region OFG including an intermediate portion of the reflection source OB2 are applicable. In the intermediate portion of the reflection source OB2, that is, the region other than the end portion, the spatial change of the reflectance is small. Therefore, even if scanning with a slightly low azimuth resolution is performed, the image quality is not greatly affected.
[0044]
Next, in step S4, full-scale imaging is performed. That is, the ignition timing controller 25 controls the delay times of the drive signals output from the plurality of pulsar circuits 12 according to the transmission / reception method set by the transmission / reception method setting unit 24. As a result, as shown in FIG. 10, the imaging regions (1) to (7) are scanned based on the transmission / reception method set for each. That is, first, the range of OA to OC is scanned using an ultrasonic beam having a relatively large diameter by the single beam transmission / multi-beam reception method. Next, the transmission / reception method is switched to the single beam transmission / reception method, and the range of OC to OD is scanned with an ultrasonic beam having a small diameter. Furthermore, the range of OD-OE and OG-OH is scanned in parallel using two ultrasonic beams by the multi-beam transmission / reception method. Next, the range of OE to OF is scanned by a single beam transmission / reception method. Further, the range of OF to OG and OH to OB is sequentially scanned by the single beam transmission / multi-beam reception method.
[0045]
By such scanning, ultrasonic echoes generated in the respective imaging regions are received by the plurality of ultrasonic transducers 11 included in the ultrasonic probe 10, and a plurality of detection signals are received from the plurality of ultrasonic transducers 11. Each is output. These detection signals are respectively input to the corresponding receivers 14, subjected to signal processing similar to that in step S <b> 1, temporarily stored in the memory 21, and then input in parallel to each system of the phase matching calculation unit 22. The
[0046]
The phase matching calculation unit 22 performs reception beam forming on the input detection signal so as to form a predetermined reception focus according to the transmission / reception method set by the transmission / reception method setting unit 24. Further, the detection data subjected to reception beam forming in the phase matching calculation unit 22 is subjected to detection waveform detection, conversion to image data, and predetermined image processing in the display image calculation unit 26. The scan format is converted. Thereby, the image data in the sound ray data space is converted into image data in the physical space. Further, the display image calculation unit 26 generates voxel data that is data about a certain volume from a plurality of pieces of tomographic data, and also performs a calculation for displaying a three-dimensional image. The calculation processing result of the display image calculation unit 26 is displayed as an image after being converted into an analog signal by the image display unit 30.
[0047]
【The invention's effect】
As described above, according to the present invention, based on the result of pre-imaging, the sector area in the subject is divided into a plurality of imaging areas, and an optimal transmission / reception method is set for each of these imaging areas. Therefore, it is possible to efficiently acquire high-quality image data in which the influence of crosstalk is suppressed.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a configuration of an ultrasonic imaging apparatus according to an embodiment of the present invention.
FIG. 2 is a diagram for explaining transmission / reception of ultrasonic waves by a single beam transmission / reception method;
FIG. 3 is a diagram for explaining transmission / reception of ultrasonic waves by a multi-beam transmission / reception method;
FIG. 4 is a diagram for explaining transmission / reception of ultrasonic waves by a single beam transmission / multi-beam reception method;
FIG. 5 is a diagram for explaining the operation of the ultrasonic imaging apparatus according to the embodiment of the present invention.
FIG. 6 is a diagram showing a three-dimensional region in a subject.
FIG. 7 is a diagram for describing a contribution rate used in a crosstalk determination unit.
FIG. 8 is a diagram for explaining a crosstalk determination method;
FIG. 9 is a diagram for explaining a crosstalk determination method;
FIG. 10 is a diagram for explaining scanning in a sector area in which a transmission / reception method is set.
FIG. 11 is a diagram for explaining scanning in an area where a multi-beam transmission / reception method is set.
[Explanation of symbols]
10 Ultrasonic probe
11 Ultrasonic transducer
12 Pulser circuit
14 Receiver
15 Preamplifier
16 TGC amplifier
17 A / D converter
20 System controller
21 memory
22 Phase matching calculator
23 Crosstalk judgment part
24 Transmission / reception method setting section
25 Firing timing controller
26 Display Image Calculation Unit
30 Image display section

Claims (6)

An ultrasonic imaging device comprising:
An ultrasonic probe that forms an ultrasonic beam by a plurality of ultrasonic transducers that operate according to a plurality of drive signals, transmits the ultrasonic beam to the subject, and receives an ultrasonic echo reflected from the subject; and
Based on the detection signal obtained by the pre-imaging, the position of the reflection source existing in the subject is grasped, and a plurality of ultrasonic echoes respectively reflected by a plurality of different reflection sources are detected by the ultrasonic probe. Determining means for determining whether or not there are reflection sources that interfere with each other when received by the touch;
Based on the determination result of the determination unit, for each of a plurality of imaging regions included in the subject, a transmission / reception method used when scanning the imaging region is selected and set from among a plurality of transmission / reception methods. A transmission / reception method setting means;
In accordance with the transmission / reception method set by the transmission / reception method setting means, one or a plurality of signals transmitted from the ultrasonic probe are delayed by delaying the plurality of drive signals supplied to the ultrasonic probe. Transmission-side signal processing means for scanning the subject with an ultrasonic beam;
A plurality of detection signals obtained by reception of ultrasonic echoes according to a transmission / reception method set by the transmission / reception method setting unit, thereby obtaining image signal related to a subject;
An ultrasonic imaging apparatus comprising: The transmission / reception method setting means (i) forms and transmits one ultrasonic beam to each of a plurality of imaging regions included in the subject, and 1 for ultrasonic echoes generated by reflection from the reflection source. (Ii) each of a plurality of ultrasonic echoes generated by transmitting a plurality of ultrasonic beams in a plurality of directions and being reflected by a reflection source in the plurality of directions, respectively. (Iii) a transmission / reception method for forming and transmitting a single ultrasonic beam and forming a plurality of reception focal points for an ultrasonic echo generated by being reflected by a reflection source. The ultrasonic imaging apparatus according to claim 1, wherein any one of them is set. The ultrasonic imaging apparatus according to claim 1, wherein the plurality of ultrasonic transducers are two-dimensionally arranged. Using an ultrasonic probe that forms an ultrasonic beam by a plurality of ultrasonic transducers that operate according to a plurality of drive signals, transmits the ultrasonic beam to the subject, and receives an ultrasonic echo reflected from the subject, An ultrasonic imaging method for imaging a subject,
Performing pre-imaging by scanning the subject with at least one ultrasound beam (a);
Based on the result of the pre-imaging performed in step (a), the position of the reflection source existing in the subject is grasped, and a plurality of ultrasonic echoes generated by being reflected by a plurality of different reflection sources are Determining whether there are reflection sources that interfere with each other when received by the ultrasound probe;
Based on the determination result in step (b), for each of a plurality of imaging regions included in the subject, a transmission / reception method used when scanning the imaging region is selected and set from among a plurality of transmission / reception methods. Performing step (c);
In accordance with the transmission / reception method set in step (c), one or a plurality of transmission signals transmitted from the ultrasonic probe are delayed by delaying the plurality of drive signals supplied to the ultrasonic probe. Scanning the subject with an ultrasonic beam (d);
A step (e) of obtaining image information relating to the subject by processing a plurality of detection signals obtained by reception of the ultrasonic echo in accordance with the transmission / reception method set in step (c);
An ultrasonic imaging method comprising: In step (c), for each of a plurality of imaging regions included in the subject, (i) one ultrasonic beam is formed and transmitted, and one ultrasonic echo is generated by being reflected by the reflection source. (Ii) For each of a plurality of ultrasonic echoes generated by transmitting a plurality of ultrasonic beams in a plurality of directions and being reflected by a reflection source in the plurality of directions, respectively. A transmission / reception method for forming one reception focus and (iii) a transmission / reception method for forming and transmitting one ultrasonic beam and forming a plurality of reception focal points for an ultrasonic echo generated by reflection from a reflection source. The ultrasonic imaging method according to claim 4, wherein any one of the above is set. The ultrasonic imaging method according to claim 4 or 5, wherein step (d) includes transmitting an ultrasonic beam using an ultrasonic probe including a plurality of ultrasonic transducers arranged in two dimensions. .

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