JPH0773579B2 - Ultrasonic diagnostic equipment - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrasonic diagnostic apparatus for transmitting and receiving ultrasonic waves to and from a subject and obtaining an ultrasonic tomographic image based on the received reflected waves, and more particularly, an ultrasonic diagnostic apparatus of electronic focus control. Regarding

[0002]

2. Description of the Related Art Conventionally, in an ultrasonic diagnostic apparatus that obtains a tomographic image by transmitting and receiving ultrasonic waves with an ultrasonic probe having a plurality of transducers, one ultrasonic beam is transmitted from a plurality of transducers. Be focused on.

Referring to FIG. 3, the transducer array 10 arranged in a straight line has 32 transducers 10-1 to 10-32. When focusing the ultrasonic beam on the point F0 at a distance S0 from the transducer array 10, the transducers 10 near the center are
A path difference occurs between the distance S0 from -16, 10-17 to the point F0 and the distance S1 from the end vibrators 10-1, 10-32 to the point F0. By setting the difference in the arrival time of the ultrasonic waves caused by this path difference S1 -S0 as the delay time (td) of the transmission timing of the ultrasonic pulse of each transducer in advance, the phase of the ultrasonic pulse is uniform at the point F0. Are tied together. As shown in FIG. 4, the ultrasonic wave transmission timing of the vibrator near the center is delayed with respect to the vibrator at the end portion where the distance to the focus (F0) is long. By delaying the transmission timing in accordance with the distance up to), when the ultrasonic pulse reaches the point F0, the point where the phases are aligned can be focused on the point F0. The curve showing the amount of delay time to be given to each transducer is the delay time curve 100 shown in FIG.

Further, also in reception, a time difference occurs in the time when the reflected wave from the point F0 reaches each transducer. A delay time setting circuit 11 shown in FIG. 5 is provided to correct this time difference and align the phases. A curve 101 showing the delay time at this time is a delay time curve at the time of reception.

The setting of the delay time as described above is performed by, for example, the delay time setting circuit shown in FIG. Delay time setting circuit is configured from the delay line 30 and the selection circuit 32, the delay line 30 is 80 pieces of input taps group (30-1, 30-2, ..., 30-80) have, select times
The path 32 is composed of 80 4 × 8 matrix circuits.

[0006] the input tap of the delay line 30 are each 2
A delay time of 0 nsec (nanosecond) is output. Input taps 30-1 20n seconds in FIG. 6, the input tap 30-2
40n seconds, ..., input tap 30-80 is set a delay time of the 1600n seconds. That is, the quantization width in this case is 20 ns, and the delay time curve 10 shown in FIG.
1 is quantized with this quantization width and approximated (111 in FIG. 7 ). This delay time setting circuit sets a delay time for each transducer as shown in FIG. 7 to focus the ultrasonic pulse.

[0007]

As described above, the delay time setting circuit includes the delay line 3 having 80 output terminals.
Although there are 0 and 80 matrix circuits, the delay time of each transducer in the central portion of the receiving transducer group is not significantly different from that of the adjacent transducer. Therefore, it is not necessary to reduce the quantization width near the center of the receiving transducer group. On the contrary, in order to reproduce the delay time curve 101 at both ends of the transducer group for reception, it is necessary to perform fine quantization because the delay time difference given to each of the adjacent transducers is large.

That is, the quantization width required to reproduce one delay curve is different at both ends and the central portion of the reception transducer group, and if the quantization width is set small, the reception transducer group will have There is a problem that the quantization width becomes unnecessarily small in the central portion, and if the quantization width is set to be large, the reproducibility of the delay curve is poor at both ends of the transducer group for reception.

Furthermore, the reduction in quantization width, increasing the number of input taps of the delay line, the number of the matrix circuit is disadvantageously increased.

The present invention has been made to solve the above problems, and an object thereof is to obtain an ultrasonic diagnostic apparatus capable of reducing the number of circuit elements without degrading the image quality.

[0011]

[Means for Solving the Problems ] To solve the above problems
Therefore, the ultrasonic diagnostic apparatus according to the present invention includes a plurality of transducers.
An ultrasonic pulse is transmitted by the probe composed of
Receiving the ultrasonic pulse reflected from the body,
A predetermined delay time amount is set in the received signal for each transducer.
Has a delay time setting means to set the delay time
Therefore, the ultrasonic pulse is focused and the ultrasonic tomographic image is obtained.
An ultrasonic diagnostic apparatus, wherein the delay time setting means is
Depending on the position of the transducer in the probe,
There are multiple delay time setting taps with the delay time amount set.
However, the difference in the delay time is arranged near the center of the probe.
In the oscillators that are used, they are becoming larger.

[0012]

In the region where the slope of the delay time curve that differs depending on the region of the probe is small, the corresponding circuit elements can be reduced by setting a large quantization width.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows a delay time setting circuit of the ultrasonic probe of this embodiment. Delay time setting circuit is delay line 2
Has 0 and the select circuit 22, delay line 20 is input <br/> force taps 20-1, 20-2, equipped with 48 20-48, the matrix circuit 22 of the selection circuit 22 is 4 × 8 -1
It has 48 matrix circuits 01, ..., 22-806. From the characteristics of the delay time shown in FIG. 2, it can be read that the delay time given to the transducers in the region where the absolute value of the delay time is large, that is, the transducers near the center of the transducer group for reception does not change significantly between the adjacent transducers. In other words, in this region, the change rate of the delay time curve 101 in the transducer array direction (the slope of the delay time curve) is small. Therefore, even if the quantization width by thinning out the long side of the tap of the delay time in the input tap group delay line 30 shown in the prior art as 40n sec, can be prior art quantizing substantially the same delay time curve. In the embodiment, the output taps 20-1 to 20-16
Output taps 20-17 to 20-4 at 20nsec intervals
Delay time is set up to 8 at 40nsec intervals. Specifically, 20-1 is 20 ns, 20-2 is 40 ns, ..., 20
-16 is set to 320 seconds, 20-17 is 360 ns, 2
0-18 is set to 400 ns, and 20-48 is set to 1600 ns.

By setting such a delay line, the delay time curve 101 is approximated to the quantized delay time curve 112 by quantization. At this time, the quantized delay time curve 112 at both ends of the transducer group for reception whose absolute value of the delay time is small
a becomes equal to the quantization delay time curve 111 described above. On the other hand, the quantization delay time curve 11 at the center of the transducer group for reception
2b is different from the quantization delay time curve 111 described above,
Since both ends of the transducer group for reception have a great influence on the focusing of the ultrasonic beam, the image quality of the tomographic image is not significantly deteriorated. For example, the basic ultrasonic beam in the normal direction of the transducer array
The delay amount for each transducer is changed to
Send and receive auxiliary ultrasonic booms with horns for basic ultrasonic
When performing small angle sectors that interpolate the beam
Increase the quantization width to ensure the lateral resolution of the wave beam.
I can't hear. However, in this example
Is the end of the probe that has a large effect on the lateral resolution of the beam.
Since the quantization width of the recent delay amount is reduced, the image quality
Can be suppressed. On the other hand, the lateral resolution is large.
At the center of the probe, where there is no significant
The circuit scale can be reduced because it is faster. did
Therefore, the circuit scale is reduced while ensuring the lateral resolution.
be able to.

By setting the delay time as described above, the number of matrix circuit elements is set to 80 in the conventional delay circuit.
It is possible to reduce the number to 48 compared to the number.

In this embodiment, the minimum delay time of reception is always corrected to be the minimum time tap of the delay line. At this time, in order to make the display start position of the image constant, the sum of the maximum delay times of transmission and reception must always be constant, so the minimum time tap for reception is used. The correction delay time is distributed to the transmission delay time. Since the start time of transmission only counts a certain period of time, it is easy to increase the maximum delay time of transmission.

[0018] In this way it is possible to minimize the delay time by allocating the delay time at the time of reception and time of transmission is always the minimum input tap of the delay line, thereby, since the reproducibility of the delay curve is improved, Quantum It is possible to prevent the error caused by the conversion from increasing.

In this embodiment, the delay lines are thinned out by one and the quantization width is 20 nsec.
Although it was set with 2 types of 0 ns, the quantization width was 20 ns,
It is also possible to set three types of 40 ns and 60 ns. For example, the output taps 20-1 to 20-24 are 20
Output taps 20-25 to 4 are 4 every 4 seconds.
It is also possible to set the output taps 20-41 to 20-48 at 60 ns intervals at 0 ns intervals.

Further, although the case where the number of output taps is 48 has been shown, the number is not limited to this.

[0021]

As described above, since the input taps of the delay line for reception are thinned out and used, it is possible to reduce the number of circuit elements and the vibration of reception which greatly affects the focusing of the ultrasonic beam. Since the quantization width at the end of the child group is set as in the conventional case, the image quality of the ultrasonic tomographic image is not deteriorated.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a delay time setting circuit of an ultrasonic diagnostic apparatus according to the present invention.

FIG. 2 is a diagram showing a quantized delay time curve according to the present invention.

FIG. 3 is a diagram showing a method of focusing an ultrasonic probe including a plurality of ultrasonic transducers.

FIG. 4 is an explanatory diagram of a delay time set at the time of transmission.

FIG. 5 is an explanatory diagram of a delay time set at the time of reception.

FIG. 6 is a configuration diagram of a conventional delay time setting circuit.

FIG. 7 is a diagram showing a conventional quantized delay time curve.

[Explanation of symbols]

10 Transducer Row 11 Delay Line (Function) 20 Delay Line (Element) 22 Select Circuit

Claims (1)

[Claims] 1. An ultrasonic wave pulse is transmitted by a probe composed of a plurality of transducers, the ultrasonic wave pulse reflected from a subject is received, and the plurality of transducers are converted into a reception signal. A delay time setting means for setting a predetermined delay time amount
In the ultrasonic diagnostic apparatus, which has an ultrasonic pulse obtained by focusing an ultrasonic pulse according to a set delay time , the delay time setting means includes:
Depending on the position, multiple delay time amounts that are mutually discrete are set.
The number of delay time setting taps is
In the transducer arranged near the center of the probe,
The ultrasonic diagnostic device is characterized in that