JPH0549290B2 - - Google Patents

Description

[Detailed description of the invention] (b) Industrial application fields The present invention relates to an ultrasonic diagnostic apparatus.

(b) Prior Art Conventionally, an ultrasonic diagnostic apparatus includes a transducer having a plurality of transducers arranged in an array.
By linearly scanning this transducer, ultrasonic waves are transmitted to the subject, and the echoes of the ultrasound reflected from various parts of the subject are received again by the transducer, which is then electrically transmitted. It is converted into an echo signal and sampled at a predetermined frequency. At this time, some systems employ a dynamic focus method in which the sampling target of the echo signal, that is, the focus, is changed depending on the depth from the transducer to each site within the subject. In this method, for example, when the depthwise region within the subject is divided into a proximal region N, an intermediate region M, and a far region F, as shown in Fig. 1, each region N, M, F
Tomographic image 1 based on individual echo signals obtained from within
A frame is formed. By the way, in the conventional method, for example, when sampling echo signal data of a nearby area N, after sampling echo signals from all areas N, M, and F,
Using only echo signals from within, other areas M,
Signal processing is performed such that the signal from F is discarded. That is, instead of focusing from the beginning and sampling echo signals from the focused areas, all echo signals from each area N, M, and F are sampled and then the focus is adjusted. Therefore, it actually takes three frames to obtain one frame of tomographic image. Therefore, there is a problem that the frame rate is low and real-time performance is still insufficient.

(c) Purpose It is an object of the present invention to solve the above-mentioned problems and to make it possible to obtain real-time tomographic images with a high frame rate using the dynamic focus method.

(d) Configuration In order to achieve the above object, the present invention provides the following features: Each time an ultrasound beam is scanned for one field,
means for outputting a focus selection signal for selecting and switching the focus in stages; and means for changing the output cycle of a trigger pulse for exciting and driving the vibrator in response to the focus selection signal each time the focus selection signal is input; Beam scanning in which the ultrasonic beam is linearly scanned by selecting a pair of transducer groups alternately in synchronization with the trigger pulse and shifting the position of each transducer group while maintaining a distance separated by a predetermined pitch. means for generating a control signal;
Only the echo signal from the focused area is sampled.

(E) Embodiments The present invention will be described in detail below based on embodiments shown in FIGS. 2 to 6. FIG. 2 is a block diagram showing the entire ultrasonic diagnostic apparatus of this embodiment. In the figure, 1 is an ultrasonic diagnostic device, 2 is a transducer for transmitting and receiving ultrasonic waves, and this transducer 2 has a plurality of transducers (not shown) arranged in an array. 4 is a pulse generation control circuit that generates pulses for exciting and scanning each vibrator of the transducer 2, and 6 is a focus of the echo signal obtained by the transducer 2 based on the output pulse from the pulse generation control circuit 4; a focus and element selection circuit that sequentially selects each vibrator to be excited in the transducer 2;
8 is a waveform shaping circuit that shapes the echo signal obtained from the transducer 2 via the focus and element selection circuit 6; 10 is a waveform shaping circuit 8;
This display circuit 10 displays an image of the echo signal that has passed through the echo signal, and this display circuit 10 includes a digital scan converter and a CRT.

FIG. 3 is a block diagram of the pulse generation control circuit 4. In the figure, 12 is an oscillator that outputs a clock pulse having a fundamental frequency, and 14 is a transducer 2 based on focus selection signals Fa and Fb output from a ternary counter 30, which will be described later.
This means changes the pulse period of the trigger pulse T that excites each vibrator of the oscillator 1.
A first subtraction counter 16 that subtracts the fundamental frequency of the clock pulse from 2 by, for example, 1/128; It is composed of a subtraction counter 18, a third subtraction counter 20 that similarly subtracts by 1/3, and a multiplexer 22 that switches the output pulses of the first to third subtraction counters 16, 18, and 20. 24 is a first monostable multivibrator that outputs a trigger pulse T that excites each vibrator of the transducer 2 in response to a pulse output from the multiplexer 22. 26 is a means for outputting a beam scanning control signal U that receives the trigger pulse T from the first monostable multivibrator 24 and alternately switches and scans the ultrasonic beam emitted from the transducer 2 at a predetermined distance. The output terminal of this counter 26 and the input terminal of the focus and element selection circuit 6 are connected to the fourth
As shown in the figure, the least significant bit of counter 26
The LSB is set to be the most significant bit MSB of the focus and element selection circuit 6. 28
30 is a second monostable multivibrator that outputs a field end signal S based on the final count output corresponding to one field scan of the ultrasound beam among the count outputs of the counter 26; 30 is a second monostable multivibrator; This means outputs focus selection signals Fa and Fb for selecting and switching the focus every one field scan of the transducer 2 in response to the field end signal S from the second monostable multivibrator 28, and this means 30 is used in this example. In this case, it is composed of a ternary counter 30.

Next, dynamic focus in the ultrasonic diagnostic apparatus 1 having the above configuration will be explained with reference to the operation of each part and the time chart of FIG. 6. In this example, in order to store the echo signal data in the digital scan converter of the display circuit 10, the scanning direction of the ultrasonic beam by the transducer 2 is set to the x direction, as shown in FIG. Let the direction be the y direction. Then, the region in the depth direction (y direction) from the transducer 2 to each site within the subject is divided into three regions, a near region N, an intermediate region M, and a far region F, and each of these regions N, M, Ultrasonic transmission and reception time within F is 0 respectively.
Correspond to ~127 counts, 128~255 counts, and 256~383 counts. Then, 0 to 383 counts are made to correspond to the Y address of the digital scan converter. When the focus is initially on the adjacent region N, the input terminal _X0 of the multiplexer 22 of the pulse generation control circuit 4, which is directly connected to the first subtraction counter 16, is connected to the supply terminal Y. Therefore, the clock pulse of the oscillator 12 is output to the Y address counter of the digital scan converter of the display circuit 10 and also to the first subtraction counter 16. A first subtraction counter 16 subtracts this clock pulse by 1/128 and applies it to a first monostable multivibrator 24 via a multiplexer 22. The first monostable multivibrator 24 outputs a trigger pulse T in response to this clock pulse. This trigger pulse T is sent to the transducer 2 and the counter 26. A counter 26 counts the trigger pulses T and outputs a beam scanning control signal U. This beam scanning control signal U is output to the focus and element selection circuit 6, so that the circuit 6 selects a group of transducers to be excited at once based on this beam scanning control signal U. In this case, since the counter 26 and the focus and element selection circuit 6 are connected as shown in FIG.
In response to the trigger pulse T, the ultrasonic beams emitted are alternately switched and scanned at predetermined distances xi, as shown by numbers 1, 2, 3, . . . in FIG. Moreover, the pulse period of the trigger pulse T is also shortened when targeting this proximity region N. Therefore, only ultrasonic echoes from within the nearby area N are received by the transducer 2, and when ultrasonic echoes from areas M and F farther than that reach the transducer 2, the ultrasonic echoes are received by the transducer 2. The group of transducers that receive waves is at a predetermined distance from this
Ultrasonic echoes from distant areas M and F are ignored since the position has already been moved to a position separated by xi. Therefore, it is not affected by multiple echoes caused by scanning the ultrasound beam. Then, when the ultrasonic beam is scanned for one field in the x direction, the counter 26 receives the last trigger pulse T of one field scan.
The count output is given to the second monostable multivibrator 28. Second monostable multivibrator 2
8 outputs a field end signal S in response to this counter output, and this field end signal S
is sent to the ternary counter 30. ternary counter 3
0 inputs a field signal S, and in response, outputs a focus selection signal from its output terminals A and B.
Output Fa and Fb. This focus selection signal
Fa and Fb are sent to multiplexer 22 and focus and element selection circuit 6, respectively.
The multiplexer 22 receives the focus selection signal Fa,
When Fb is input, the connection of the input/output terminal is switched, and the input terminal X1 directly connected to the second subtraction counter 16 is connected to the output terminal Y. At the same time, the focus and element selection circuit 6 sets the focus to the next intermediate region M based on the input focus selection signals Fa and Fb. In this way, each area N,
A focus is set for each of M and F, and one field's worth of ultrasonic beam scanning is performed. Therefore, the longer the region F is, the longer the period of the trigger pulse T becomes, and the longer the scanning time for one field of the ultrasonic beam becomes. However, in any area N, M, F, the ultrasonic beam is
are switched and scanned alternately. After setting the focus, each echo signal obtained by the transducer 2 is received and focused in the focus and element selection circuit 6 corresponding to each region N, M, F, and then the waveform shaping circuit 8 forms the waveform. The data is shaped and sent to the display circuit 10.

(f) Effects As described above, according to the present invention, the focus is adjusted according to the depth from the transducer to each part within the subject, and the echo signal from the focused point is sampled. , after sampling all the conventional echo signals,
The time required to form one frame of a tomographic image is shorter than that in which the focus is adjusted, and therefore the frame rate can be increased. Therefore, a tomographic image with high real-time performance can be obtained, and an excellent effect is exhibited in that diagnosis can be performed more accurately.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing the depthwise regions within the subject divided into sections, FIGS. 2 to 6 show embodiments of the present invention, and FIG. 2 is a block diagram showing the entire ultrasonic diagnostic apparatus. Figure 3 is a block diagram of the pulse generation control circuit, Figure 4 is a wiring diagram showing the connection relationship between the counter, focus and element selection circuit, Figure 5 is an explanatory diagram of the dynamic focus, and Figure 6 is This is a time chart of signals output from the pulse generation control circuit. 1 is an ultrasonic diagnostic device, 2 is a transducer,
4 is a pulse generation control circuit, 14 is a pulse period changing means, 16 is a first subtraction counter, 18 is a second subtraction counter, 20 is a third subtraction counter, 22 is a multiplexer, 26 is a counter, and 30 is a ternary counter.

Claims (1)

[Scope of Claims] 1. A transducer having a plurality of transducers arranged in an array is provided, and the focus of ultrasonic echoes of the transducer is adjusted to the depth from the transducer to each site within the subject. In an ultrasonic diagnostic apparatus using a dynamic focus method that changes the focus according to , every time this focus selection signal is input,
means for changing the output cycle of a trigger pulse for exciting and driving the vibrator in response to this; An ultrasonic diagnostic apparatus comprising: means for generating a beam scanning control signal for linearly scanning an ultrasonic beam by shifting and selecting a group of transducers.