JP4246853B2 - Ultrasonic diagnostic equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an ultrasonic diagnostic apparatus, and more particularly to imaging of a three-dimensional region.
[0002]
[Prior art and problems]
Conventionally, various three-dimensional ultrasonic image forming methods have been proposed. For example, in JP-A-10-33538, an ultrasonic beam is scanned in a three-dimensional space, echo data on each ultrasonic beam is referred to along the time series, and a predetermined volume rendering operation is performed on them. It is disclosed that a three-dimensional image is formed by performing the above. According to this three-dimensional image, for example, the fetus can be represented in three dimensions, so that the accuracy of ultrasonic diagnosis can be improved.
[0003]
In the above-described apparatus, an ultrasonic probe for taking in three-dimensional echo data that mechanically swings and scans the array transducer in a direction orthogonal to the scanning plane is used. As described above, since the data processing path (line-of-sight direction) coincides with the direction of the ultrasonic beam, a three-dimensional image can be formed as a result by processing the input echo data in time series order. For this reason, in the above apparatus, there is no request for special deflection control for each ultrasonic beam constituting each scanning plane.
[0004]
According to the above-described swing scanning, a substantially pyramid-shaped data capturing area spreading in the deep portion can be formed. In the conventional image processing, the data capture area is projected from the probe side, that is, from above. However, depending on the diagnostic purpose, for example, the data capture area may be projected from the side, that is, from the lateral direction. is there. In that case, if the same scanning plane is always formed, the ratio of the non-imaged portion increases and there is a problem that there is a lot of waste. In addition, there is a problem that an address calculation for specifying data (that is, intersection coordinates) corresponding to each line of sight on each scanning plane becomes complicated.
[0005]
For example, in a state where an ultrasonic probe having a linear array transducer is in contact with the body surface, the ultrasonic probe is translated in a direction perpendicular to the scanning plane, thereby forming a cube formed thereby. It is also possible to project the three-dimensional capture area from the lateral direction. According to this method, the entire area can be imaged, and complicated address calculation for specifying the data on the line of sight is unnecessary. However, if the scanning of the ultrasound probe is performed manually, there is a high possibility that distortion will occur between the scanning planes, and even if the scanning is performed mechanically, the echo data passes through a narrow area such as a gap. There is a problem that it cannot be applied to a purpose of taking in
[0006]
The present invention has been made in view of the above-described conventional problems, and it is an object of the present invention to realize beam scanning control suitable for projection processing on the premise of swing scanning of a scanning surface.
[0007]
Another object of the present invention is to realize beam scanning control adapted to a case where a plurality of scanning planes are arranged non-parallel to each other or a plurality of lines of sight are arranged non-parallel to each other.
[0008]
[Means for Solving the Problems]
(1) In order to achieve the above object, according to the present invention, a scanning surface formed by scanning an ultrasonic beam in the first scanning direction is swung in the second scanning direction, thereby moving in the second scanning direction. A transmission / reception unit that forms a plurality of scanning planes arranged in parallel, and a line-of-sight group that spreads radially from the viewpoint so that each line of sight passes through the plurality of scanning planes, and sequentially refers to echo data along each line of sight Image forming means for calculating pixel values and thereby forming an ultrasonic image, and deflection control means for controlling the deflection angle of each ultrasonic beam in the scanning plane in accordance with the swing angle of each scanning plane. It is characterized by including these.
[0009]
According to the above configuration, the deflection angle of each ultrasonic beam constituting each scanning plane is determined at each swing scanning position according to the swing angle at that time (and according to the positional relationship between the virtual viewpoint and the projection plane). Is done. Here, if the diagnostic depth (transmission pulse repetition period) for each ultrasonic beam is variably set according to the swing angle, the frame rate can be improved. Furthermore, rational sampling can be realized by adaptively setting the sampling frequency of the echo data. On the other hand, data necessary for projection may be acquired by performing data thinning or data interpolation on each scanning plane.
[0010]
As described above, according to the present invention, the arrangement pattern of the ultrasonic beam can be adaptively changed on each scanning plane, and the range in which the ultrasonic beam is scanned can be limited to the range used for projection. As a result, it is possible to efficiently transmit and receive ultrasonic waves. In particular, if the arrangement pattern of the ultrasonic beams on each scanning plane is matched with the arrangement of the line-of-sight groups, the burden on the projection process can be greatly reduced. The first scanning direction is an electronic scanning direction, and the second scanning direction is preferably a mechanical scanning direction. However, electronic scanning may be performed in both scanning directions using a 2D array transducer. The present invention is also applicable to Doppler information processing.
[0011]
Preferably, the wave transmitting / receiving means includes an array transducer in which a plurality of vibrating elements are aligned in the first scanning direction, and electronically scanning them, and the array transducer in the second scanning direction. A swing scanning mechanism for swing scanning.
[0012]
Preferably, each scanning plane closer to the viewpoint side than the scanning plane orthogonal to the central line of sight in the line of sight group has a shape in which the lower side is smaller than the upper side, and each of the scanning planes located on the back side from the orthogonal scanning plane The scanning surface has a shape in which the lower side is larger than the upper side.
[0013]
(2) In order to achieve the above object, the present invention sets a scanning control means for forming a plurality of scanning planes and a line of sight that passes through each scanning plane from the viewpoint, and executes data calculation along each line of sight And an image forming unit that forms a projection image, wherein the scanning control unit arranges each ultrasonic beam that constitutes the scanning surface according to a change in a passing region of the line-of-sight group on each scanning surface. Is characterized by adaptively changing.
[0014]
When a plurality of scanning planes are arranged non-parallel to each other, or when a plurality of lines of sight are set non-parallel to each other, the projected range on each scanning plane is different. Therefore, on each scanning plane, the beam scanning range is adaptively set according to the shape of the projection range (passage range of the line of sight group).
[0015]
Preferably, the plurality of scanning planes spread radially and are formed non-parallel to each other, and the line-of-sight group has an array that extends two-dimensionally from the viewpoint.
[0016]
Preferably, the plurality of scanning planes other than the scanning plane orthogonal to the central visual line in the visual line group have a trapezoidal shape.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
Preferred embodiments of the present invention will be described below with reference to the drawings.
[0018]
First, the principle will be described with reference to FIGS. In FIG. 1, the probe 10 is a linear array probe in this example. The front end surface functions as a wave transmitting / receiving surface, and the front end surface is brought into contact with the body surface directly or indirectly through water or the like. The probe 10 is swung and scanned by a manual or mechanical mechanism. Here, the wave transmission / reception surface is set as the center point of oscillation, but the present invention is not limited to this.
[0019]
In the probe 10, an array transducer is provided in a direction perpendicular to the paper surface in FIG. 1, and the scanning plane 14 is formed by electronic scanning of the array transducer. When the probe 10 is oscillated and scanned, the scanning surface 14 is also oscillated and scanned in the θ direction in the drawing, that is, a plurality of scanning surfaces are formed in the θ direction. As a result, a pyramid-shaped data capturing area 16 having the wave receiving / receiving surface as a vertex is formed. In the present embodiment, a projection image is formed by viewing the data capture area 16 from the lateral direction. In this case, reference numerals 100 and 102 in the figure indicate ranges included in the visual field viewed from the viewpoint O. . Incidentally, reference numerals 18 and 20 in FIG. 1 indicate the upper and lower ends of the line-of-sight group set uniformly and radially from the viewpoint O toward the projection plane 12. In the line-of-sight group, the lines of sight are evenly arranged in a matrix.
[0020]
As shown in FIG. 1, the projection ranges 100 and 102 are different depending on the swing angle of each scanning plane. In the present embodiment, the projection ranges 100 and 102 correspond to this depending on the swing angle of the scanning plane on each scanning plane. Thus, deflection control for each ultrasonic beam is performed. This will be further described with reference to FIG.
[0021]
FIG. 2 shows the relationship between the field of view and the scanning plane when the projection plane 12 is viewed from the viewpoint O, and each symbol shown in FIG. 1 corresponds to each symbol in FIG. Here, the X direction indicates the electronic scanning direction of the probe 10 shown in FIG. However, in the conventional electronic linear scanning, an ultrasonic beam is always formed in a direction orthogonal to the array transducer. However, in the present embodiment, depending on the above-described scanning surface swing angle and other conditions. The deflection angle of the ultrasonic beam is set.
[0022]
This will be described in detail. As shown in FIG. 2, when the projection surface 12 is a rectangular area, a line-of-sight group is defined in a range surrounded by four lines of sight 18 to 24 corresponding to the four corners. In forming a projection image, it is sufficient to capture data only in a trapezoid (including a rectangle) area corresponding to the line-of-sight group passing area on each scanning plane. In FIG. 2, examples of such ranges are indicated by reference numerals 100 and 102.
[0023]
FIG. 3 shows an ultrasonic beam electronic scanning method for forming the ranges 100 and 102. As shown to (A), when forming the scanning surface which exists in the projection surface 12 side rather than the scanning surface orthogonal to the central visual line which makes the center of a visual line group, the trapezoidal scanning range 100 whose lower side is longer than an upper side is shown. Is set. In this case, each ultrasonic beam is set to spread radially from each transmission / reception point on the array transducer. Symbol Q indicates one of the transmission / reception points, and φ indicates the deflection angle. Incidentally, reference numerals 30 and 32 indicate both ends of the trapezoidal region described above.
[0024]
Further, as shown in (B), a trapezoidal scanning range 102 having a lower side shorter than the upper side is formed on the scanning surface closer to the viewpoint O than the scanning surface orthogonal to the central line of sight described above. Ultrasonic beams corresponding to the ends of range 102 are indicated by reference numerals 34 and 36. Here, each ultrasonic beam is set in a concentric arrangement in the center from each transmission / reception point of the array transducer. Incidentally, on the scanning plane orthogonal to the central line of sight, each ultrasonic beam is set in a direction orthogonal to the array transducer 11. Conversely, trapezoidal scanning of an ultrasonic beam as shown in (A) or (B) is performed on the other scanning planes.
[0025]
Here, as is clear from the comparison between FIGS. 3A and 3B, the scan depth farther than the scan plane close to the viewpoint O is set deeper. That is, it is possible to prevent useless use of echo data by adaptively setting the diagnostic depth for each scanning plane in this way. In other words, there is an advantage that the overall frame rate for forming the three-dimensional data capture area can be improved by rationally setting the ultrasonic pulse transmission repetition period.
[0026]
3A and 3B, reference numerals 300 and 302 indicate the arrangement of sample points. Each sample point corresponds to the intersection of the scanning plane and the line of sight. As shown in the drawing, the direction of each ultrasonic beam is set according to the line-of-sight group arrangement, and the ultrasonic beam array matches the line-of-sight group arrangement on the scanning plane. At the same time, the sampling rate also matches the line-of-sight group arrangement, that is, the sampling rate of the A / D converter or sampler is adaptively variably set according to the swing angle of the scanning plane. For example, as shown in (A), since the interval between the lines of sight increases on the scanning surface on the back side, the sampling interval is set to be large following this, while the viewpoint O is set as shown in (B). Since the interval between the lines of sight becomes small on the scanning plane close to, the sampling interval is set to be small following this. Of course, it is also possible to acquire data on necessary sample points by using data interpolation and thinning without depending on such a variable sampling rate.
[0027]
Therefore, if a projected image is formed in accordance with the principle as described above, efficient image processing can be realized without wasteful transmission and reception, and moreover, complicated calculation for specifying echo data on the line of sight in the image processing is performed. Since it becomes unnecessary, there is an advantage that quick and simple image processing can be realized.
[0028]
In forming each scanning plane, in this embodiment, the number of ultrasonic beams is set to be the same, and the number of sample points is also set to be the same as the number of line-of-sight groups. Of course, when the number of data differs between scanning planes, projection processing may be performed by applying the above-described data thinning or interpolation. The projection method is not limited to that shown in FIG. 1 and the like, and various projection methods can be applied. In any case, in the present embodiment, since the deflection control of the ultrasonic beam is performed according to the intersection relationship between the line-of-sight group and each scanning plane, the above-described advantages can be obtained.
[0029]
Next, the overall configuration of an ultrasonic diagnostic apparatus to which the above principle is applied will be described with reference to FIG. As shown in FIG. 1, the probe 10 includes an array transducer in which a plurality of vibrating elements are arranged on a straight line. The probe 10 is mechanically rocked and scanned by the scanning mechanism 15 in this embodiment. Incidentally, the swing angle at that time is detected by an angle detector (not shown), and the angle value is output to the scanning control unit 42. The scanning control unit 42 is means for controlling the swing scanning by the scanning mechanism 15 and the electronic scanning of the ultrasonic beam (transmission beam and reception beam). In this embodiment, the scanning control unit 42 calculates a beam transmission / reception origin and a deflection angle of each ultrasonic beam on each scanning plane according to projection conditions such as the coordinates of the viewpoint O and the coordinates of the projection plane 12. 44. Information on the origin Q of the transmission / reception origin and the deflection angle φ calculated by the beam direction calculator 44 is sent to the transmitter 46 and the receiver 48. Further, the scanning control unit 42 controls the sampling rate of the A / D converter 49 or the sampler at the subsequent stage, that is, as shown in FIG. 3, the sampling rate according to the swing angle of the scanning plane and the beam address. The variable setting is performed.
[0030]
The transmission unit 46 has a transmission beam forming function, and the reception unit 48 has a reception beam forming function. Specifically, in the reception unit 48, a plurality of reception signals acquired in the reception opening are phased and added. The reception signal thus generated is converted into a digital signal by the A / D converter 49, detected by the detector 50, and sent to the image processing unit 52.
[0031]
Various methods can be applied as the received signal processing method, and for example, quadrature detection may be used. Further, the present invention can be applied to a case where a projected image is formed using Doppler information in addition to a case where a projected image is formed using the luminance of echoes.
[0032]
In the present embodiment, the image processing unit 52 includes a 2D memory 56 and an accumulator 54. The accumulator 54 is a circuit that refers to echo data sequentially from the viewpoint O for each line of sight, and executes predetermined data operations on them. For example, processing based on integration processing, volume rendering, or the like can be given as the calculation. The processing result is stored in the 2D memory 56. The 2D memory 56 stores the calculation results for each line of sight, and the past accumulated results output from the 2D memory 56 and the data on the current scanning plane are processed in the accumulator 54, which is processed for each scanning. It will be repeated for each face. Therefore, in principle, the projection image is completed when the last scanning plane is processed, and the projection image is displayed on the display unit 58.
[0033]
In the present embodiment, as described above, the array of sampling data can be matched to the line-of-sight group on each scanning plane by controlling the deflection of the ultrasonic beam and adjusting the sampling rate, as shown in FIG. In addition, it is possible to realize a sequential and simple accumulation operation for each frame. That is, there is an advantage that it is not necessary to calculate a special data address. Of course, various methods can be applied as the image processing method.
[0034]
【The invention's effect】
As described above, according to the present invention, when a plurality of scanning planes are arranged non-parallel to each other or when a plurality of lines of sight are arranged non-parallel to each other, a reasonable ultrasonic beam scanning is performed. Control can be realized.
[Brief description of the drawings]
FIG. 1 is a diagram for explaining the principle of the present invention.
FIG. 2 is a diagram for explaining the principle of the present invention.
FIG. 3 is an explanatory diagram for illustrating scanning of deflection of an ultrasonic beam.
FIG. 4 is a block diagram showing the overall configuration of the ultrasonic diagnostic apparatus according to the present embodiment.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 Probe (probe), 12 Projection surface, 14 Scan surface, 15 Scan mechanism, 42 Scan control part, 44 Beam direction calculator, 46 Transmission part, 48 Reception part, 52 Image processing part, 58 Display part.

Claims (6)

A transmission / reception unit that swings and scans a scanning surface formed by scanning an ultrasonic beam in the first scanning direction in the second scanning direction, thereby forming a plurality of scanning surfaces arranged in the second scanning direction;
A line-of-sight group that spreads radially from the viewpoint is set so that each line of sight passes through the plurality of scanning planes, and pixel values are calculated by sequentially referring to echo data along each line of sight, thereby obtaining an ultrasound image. Image forming means for forming;
Deflection control means for controlling the deflection angle of each ultrasonic beam in the scanning plane according to the swing angle of each scanning plane;
An ultrasonic diagnostic apparatus comprising: The apparatus of claim 1.
The wave transmitting / receiving means includes
An array transducer in which a plurality of vibrating elements are aligned in the first scanning direction and are electronically scanned;
A swing scanning mechanism that mechanically swings and scans the array transducer in the second scanning direction;
An ultrasonic diagnostic apparatus comprising: The apparatus of claim 1.
Each scanning plane closer to the viewpoint side than the scanning plane orthogonal to the central visual line in the line of sight group has a shape in which the lower side is smaller than the upper side,
The ultrasonic diagnostic apparatus according to claim 1, wherein each of the scanning surfaces on the back side of the orthogonal scanning surface has a shape in which the lower side is larger than the upper side. Scanning control means for forming a plurality of scanning planes;
An image forming unit that sets a line-of-sight group that passes through each scanning plane from a viewpoint, executes data calculation along each line of sight, and forms a projection image;
Including
The ultrasonic diagnostic apparatus characterized in that the scanning control means adaptively changes an array pattern of ultrasonic beams constituting the scanning surface in accordance with the shape of the passing region of the line-of-sight group on each scanning surface. . The apparatus of claim 4.
The plurality of scanning planes are radially spread as a whole and formed non-parallel to each other,
The ultrasonic diagnostic apparatus, wherein the line-of-sight group has an array that extends two-dimensionally from a viewpoint. The apparatus of claim 5.
A plurality of scanning planes other than the scanning plane orthogonal to the central line of sight in the line of sight group have a trapezoidal shape.

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