JPH0654846A - Ultrasonic diagnostic device - Google Patents

Abstract

PURPOSE:To obtain an image in which distance resolution is satisfactory in the shallow part area of an examinee and also, penetration is satisfactory in its deep area without converting an ultrasonic wave sent into the examinee from an ultrasonic probe to a wide band. CONSTITUTION:In the ultrasonic diagnostic device having a transmission circuit 1, an ultrasonic probe 2, a receiving circuit 3, a DSC 4, a display device 5 and a CPU 6, a transmitting frequency control circuit 11 and a receiving frequency band control circuit 12 are provided and at the time of transmission, vibrators of #1, #2 and #9, #10 of a vibrator element group (aperture) of #1-#10 are driven by a low frequency and vibrators of #3-#8 are driven by a high frequency. Subsequently, at the time of reception, in accordance with the depth of an echo, the frequency band of reception is set to a high frequency and a low frequency in a shallow part and a deep part, respectively.

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,
In particular, the technique is suitable as a technique for improving both the resolution of the shallow region and the penetration of the deep region of the subject in the ultrasonic image for diagnosis.

[0002]

2. Description of the Related Art As is well known in the field of ultrasonic diagnostic equipment, the distance resolution (hereinafter referred to as resolution) in the depth direction of a subject becomes better as the frequency of ultrasonic waves becomes higher. Then, the higher the frequency, the greater the influence of the attenuation of ultrasonic waves in the living body, and the resolution is improved in the shallow portion where the influence of the ultrasonic waves is less, but the penetration in the deep portion is deteriorated. In order to improve deep penetration, it is necessary to lower the frequency of ultrasonic waves in order to reduce the attenuation of ultrasonic waves in the body, but lowering the frequency of ultrasonic waves lowers the resolution. .

As described above, the improvement in resolution and the improvement in penetration are in a trade-off relationship, and making them compatible has been one of the themes in this field. One of the solutions to this theme is the technology known from Japanese Patent Publication No. 62-24094. This technique is called a dynamic filter.

[0004]

Briefly stated, the technique disclosed in the above-mentioned publication provides a bandpass filter circuit capable of widening the band of ultrasonic waves transmitted to the inside of a subject and varying the band within a receiving circuit. Provided, transmitting a wideband ultrasonic wave into the subject from the probe, when receiving the echo signal from the subject, continuously the pass band of the bandpass filter with the passage of the reception time, namely, The pass band is changed from a high frequency to a low frequency as the echo signal changes from the shallow region to the deep region of the subject. However, in order to carry out this technique and obtain the effect described in the publication, it is necessary to widen the band of ultrasonic waves to be transmitted, but the pulse wave transmission technique currently used in the ultrasonic diagnostic apparatus has a limit in widening the band. However, the current situation is that the desired effects have not been achieved.

An object of the present invention is to provide an ultrasonic diagnostic apparatus capable of obtaining an image with excellent resolution in the shallow region and good penetration in the deep region without widening the bandwidth of the transmitted ultrasonic wave. It is in.

[0006]

An object of the invention is to provide an ultrasonic probe having a plurality of transducer elements arranged in an array and a plurality of the transducer elements which are adjacent to each other as a block. An ultrasonic wave transmission circuit that supplies a pulse voltage to each of the transducer elements with a predetermined delay time to transmit an ultrasonic beam from the probe into the subject, and the probe for the transmission. In an ultrasonic diagnostic apparatus having a receiving circuit for processing the echo signal received, a pulse voltage supplied to a transducer element group forming a block in order to form the ultrasonic beam of the transmitted wave in the transmitting circuit. A transmission frequency control circuit capable of setting at least two types of frequencies according to the delay time is provided, and the reception circuit switches the passing frequency band of the echo signal in accordance with the transmission frequency in time. Is achieved by providing the reception frequency band control circuits that.

[0007]

In the above structure, the transmission beam is supplied to the plurality of transducer elements adjacent to each other by the transmission circuit with a pulse voltage with a predetermined delay time for each element. The frequency of the pulse voltage is the transmission voltage. The frequency control circuit sets a plurality of frequencies corresponding to the delay time. Therefore, a high-frequency ultrasonic pulse is transmitted from a certain transducer element, and a low-frequency ultrasonic pulse is transmitted from a certain transducer element. That is, the transmitted beam is a mixture of ultrasonic waves of high and low frequencies. Then, at the time of reception, the pass band of the reception frequency band control circuit in the reception circuit is switched in correspondence with the frequency of the transmitted wave at a time corresponding to the depth of echo generation. This switching is performed so that the region where the echo generation area is shallow corresponds to the high frequency of the transmitted wave and the deep region corresponds to the low frequency of the transmitted wave.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. FIG. 1 is a block diagram showing a schematic configuration of the ultrasonic diagnostic apparatus of the present invention. In FIG. 1, reference numeral 1 denotes a wave transmission circuit, which is composed of a wave transmission pulser, a wave transmission delay circuit, a transducer element switching circuit, and the like as in the conventional apparatus. Which are arranged in a rectangular shape, an acoustic matching layer and an acoustic lens are arranged on the front surface, and a sound absorbing material is arranged on the rear surface, which are housed in a case,
3 is a receiving circuit, which is a receiving amplifier circuit, a phasing circuit, a detection circuit,
Consists of TGC circuit etc., 4 is digital scan
A converter (hereinafter referred to as DSC), which includes an A / D converter, a buffer memory, a frame memory, etc.,
A display device 5 comprises a D / A converter and a CRT.

The present invention provides a transmission frequency control circuit 11 and a reception frequency band control circuit 12 in the above structure. The transmission frequency control circuit 11 is connected to the transmission circuit 1 as shown in FIG. 1, and sets a plurality of high-frequency pulse frequencies to be supplied to the transducer elements under the control of the CPU 6. For example, in the high-voltage pulse generation circuit By changing the pulse width applied to the gate of the high withstand voltage FET of, the frequency of the high voltage pulse is 2.5MHz and 5M.
Two types of Hz can be set.

The receiving frequency band control circuit 1
Reference numeral 2 is connected to the receiving circuit 3, and the frequency band of the amplifying circuit in the receiving circuit 3 is controlled by the CPU 6 to correspond to the frequency of the transmitted wave in accordance with the signal reception time from the echo generation depth region in the subject. To control it. For example, two systems of bandpass filters are provided in the amplification circuit in the reception circuit 3, one of which is 2.5 MHz according to the above-mentioned example.
For the other, set another one for 5MHz, use them for 5MHz at the reception start time, and 2.5MHz at the timing of receiving deep echo of 10cm to 12cm or more.
It is designed to be switched for use.

Next, the ultrasonic wave transmitting / receiving operation of the present invention will be described with reference to FIG. FIG. 2 shows ultrasonic beams # 1 to # 10.
10 shows the case where the transducer elements are formed so as to form one block. In this example, the four elements # 1, # 2 and # 9, # 10 are driven by a low frequency pulse of 2.5 MHz, and the six elements # 3 to # 8 are 5 MH.
It is driven by a high frequency pulse of z. Of course, it goes without saying that the high-voltage pulse to each of the elements # 1 to # 10 is applied with a delay time so that the transmission pulse from each element is focused at a predetermined depth point in the subject. The ultrasonic waves transmitted to the inside of the subject are partially reflected at the boundary surface of the tissues in the subject having different acoustic impedances. The reflected ultrasonic waves are 5MHz and 2.5MHz of the transmitted wave.
Ultrasonic waves are included.

In this embodiment, the echoes from the inside of the subject are received by the transducer elements # 1 to 10 involved in the transmission of the probe. The received signal is amplified by the receiving and amplifying circuit in the receiving circuit 3, passes through the receiving and phasing circuit and the detecting circuit, and is transmitted to the TGC.
Input to the circuit. This TGC circuit increases the amplification factor of an input signal over time, and the output of the reception frequency band control circuit 12 controlled by the CPU 6 causes a predetermined time from the start of reception, for example, a time corresponding to an echo depth of 10 cm of 5 MHz. 2.5M from the time when the echo signal of 10cm is passed and the echo depth exceeds 10cm.
Pass the Hz echo signal. For this reason, the wave receiving and amplifying circuit incorporates bandpass filters each having a predetermined bandwidth with respect to the center frequencies of 5 MHz and 2.5 MHz.

The echo signal processed as described above is a DS
It is written to C4 every time ultrasonic waves are transmitted / received, then read in synchronization with the sweep of CRT5, and D / A converted to CRT5.
Is displayed on the screen. The ultrasonic image displayed on the screen has high resolution in the shallow part of the subject because of high-frequency ultrasonic components, and penetration in the deep part of the subject due to low-frequency ultrasonic components. It will be good.

In the above embodiment, the case where the block transducer element group of the ultrasonic probe is driven by the pulse voltage of two kinds of frequencies has been described, but the present invention is not limited to this, for example, 5 MHz, You may increase the kind like 3.5MHz and 2MHz.

[0015]

As described above, according to the present invention, an image having excellent resolution in the shallow region of the subject and excellent penetration in the deep region of the subject can be obtained without using a wideband ultrasonic transmission technique. Will be obtained.

[Brief description of drawings]

FIG. 1 is a block diagram showing the configuration of an ultrasonic diagnostic apparatus according to an embodiment of the present invention.

FIG. 2 is a diagram illustrating a driving method of a block transducer element group.

[Explanation of symbols]

 1 wave transmission circuit 2 ultrasonic probe 3 reception circuit 6 CPU 11 wave transmission frequency control circuit 12 wave reception frequency band control circuit

Claims (1)

[Claims] 1. An ultrasonic probe formed by arranging a plurality of transducer elements in an array and a plurality of transducers adjacent to each other are set as a block, and a predetermined element is provided to each of the transducer elements. An ultrasonic wave transmission circuit that supplies a pulse voltage with a delay time to transmit an ultrasonic beam from the probe into the subject, and a reception that processes an echo signal received by the probe for the transmission. In an ultrasonic diagnostic apparatus including a circuit,
The transmission circuit is provided with a transmission frequency control circuit capable of setting at least two types of frequencies of the pulse voltage supplied to the transducer element group forming the block for forming the ultrasonic beam of the transmission wave. The ultrasonic diagnostic apparatus is characterized in that the receiving circuit is provided with a receiving frequency band control circuit that switches the pass frequency band of the echo signal in accordance with the frequency of the transmitted wave in time correspondence.