JPH02271842A - Ultrasonic diagnostic device - Google Patents

Abstract

PURPOSE:To realize ultrasonic tissue diagnostic with high accuracy by switching an up chirp pulse and a down chirp pulse for which energy is different from that of this up chirp pulse, executing pulse compression and calculating a parameter concerning the dependency of an echo signal to the energy of a transmitted ultrasonic pulse based on comparison between obtained signals. CONSTITUTION:The up chirp pulse is generated from an up chirp transmitter 4, supplied through a switch 3 and transmission circuit 2 to an ultrasonic vibrator 1 and transmitted into a reagent. Next, switches 3 and 7 are changed over by a control circuit 14 and the down chirp pulse is transmitted into the reagent. The ultrasonic vibrator 1 receives the echo signal reflected from the reagent, supplies the echo signal through a reception circuit 6 and the switch 7 to a down chirp compression circuit 9, executes the pulse compression and reads the obtained signals by a scan converter 11. Then, the signals are converted to television signals and afterwards, the signals are supplied to an arithmetic circuit 12. The arithmetic circuit 12 compares and calculates these signals and the parameter concerning the dependency of the echo signal to the energy of the transmitted ultrasonic chirp pulse is calculated and supplied to a display device 13.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to an ultrasound system that transmits an ultrasound pulse into a living body, receives the echo signal, performs signal processing, and projects an ultrasound image. This invention relates to diagnostic equipment.

[Conventional technology]

Conventionally, ultrasonic pulses are transmitted into a subject such as a living body, and after receiving an ultrasound echo signal reflected inside the subject, the attenuation, scattering, sound velocity, nonlinear characteristics, etc. of the echo signal are measured. Attempts have been made to measure quantitatively and diagnose the properties (for example, softness and hardness) of tissues present inside a subject based on this measurement data. Among such attempts, there are
As disclosed in Publication No. 138, the energy of the transmitted ultrasound transmitted into the subject from an ultrasound transducer provided in an ultrasound probe is changed, and in that case, the energy is changed linearly. Due to the well-known property (tissue nonlinearity) that the intensity of the ultrasound echo signal reflected by the tissue inside the subject does not necessarily change linearly even when There are some methods that attempt to diagnose the properties of the tissue based on changes in the received echo signal.

[Problem to be solved by the invention]

JP-A-61-11025, 61-76138 mentioned above
In the conventional ultrasonic diagnostic apparatus as disclosed in the above publication, methods for changing the energy of transmitted ultrasonic waves include changing the drive voltage of the pulse that drives the ultrasonic probe, and When a pulse consists of multiple consecutive waves, for example an ultrasonic burst wave, the wave number of the pulse is changed, so when the driving voltage or wave number of the pulse is changed, the energy of the transmitted ultrasonic wave changes at the same time. The shape of the envelope of this ultrasonic wave itself also changes, and as a result, the frequency components of the ultrasonic wave change. In this way, when the frequency of ultrasound changes, the properties such as the attenuation rate of the ultrasound also change, so even if you measure the change in the intensity of the received echo signal, the properties of the ultrasound itself, which should be used as a reference, have already changed. Therefore, it was not possible to diagnose the tissue properties within the subject with high accuracy.

The purpose of the present invention is to solve the above-mentioned problems and to achieve extremely high precision ultrasonic energy by using up-chirp pulses and down-chirp pulses to make it possible to vary the ultrasonic energy without changing the frequency components of the two. It is an object of the present invention to provide an ultrasonic diagnostic device that can perform sonic tissue diagnosis.

[Means and effects for solving the problem] The present invention transmits an ultrasonic chirped pulse into a living body, receives the echo signal, and processes the signal obtained by pulse-compressing the echo signal. In an ultrasonic diagnostic apparatus that displays an ultrasound image using a wave transmitting means that switches and transmits an up-chirp pulse and a down-chirp pulse having a different energy from the up-chirp pulse, and Based on a comparison between a pulse compression means that performs up-chirp compression and down-chirp compression of an echo signal in response to transmission, and signals obtained by the up-chirp compression and down-chirp compression,
The present invention is characterized by comprising calculation means for calculating a parameter regarding the dependence of the echo signal on the energy of the transmitted ultrasonic chirp pulse.

In the ultrasonic diagnostic apparatus of the present invention, the up-chirp pulse and the down-chirp pulse with different ultrasonic energy are used as the transmitted ultrasonic waves, so the chirp pulse has a frequency that remains constant even when the ultrasonic energy is changed. Since it is possible to keep the components the same, the calculation means compares and calculates the signals obtained from the received echo signal by up-chirp compression and down-chirp compression, and converts the echo signal into a transmitted ultrasonic chirp pulse. It is possible to obtain parameters related to the energy dependence of the energy with extremely high accuracy, and these parameters represent nothing but the properties of the tissue to be diagnosed.

〔Example〕

FIG. 1 is a block diagram showing the configuration of a first embodiment of an ultrasonic diagnostic apparatus according to the present invention. The ultrasonic transducer l that transmits and receives ultrasonic waves is configured so that an up-chirp transmitter 4 and a down-chirp transmitter 5 can be connected alternately via a transmitting circuit 2 and a first changeover switch 3. .

Further, the echo signal received by the ultrasonic transducer 1 is alternately supplied to the up-chirp compression circuit 8 and the down-chirp compression circuit 9 via the reception circuit 6 and the second changeover switch 7, and The output signals of the chirp compression circuit and the down-chirp compression circuit are supplied to an arithmetic circuit 12 via scan converters 10 and 11, respectively, and the output signal of the arithmetic circuit 12 is supplied to a display device 13.

Here, the first and second changeover switches 3 and 7 are driven by the control circuit 14 in synchronization with the scanning period.

Next, the operation of this first embodiment will be explained. First, drive the selector switch 3.7 to the position shown by the solid line in FIG.
As shown in FIG. 2A, the up-chirp transmitter 4 generates an up-chirp pulse whose frequency increases continuously over time, and transmits this to the ultrasonic transducer via the switch 3 and the transmission circuit 2. 1 to generate an up-chirp pulse, which is transmitted into the subject. The echo reflected from the object is received by the ultrasonic transducer 1 and converted into an echo signal, which is then subjected to processing such as amplification and STC in the receiving circuit 6, and then passed through the switch 7 to the up-chirp compression circuit 8. The signal is then frequency compressed and the amplitude is amplified as shown in FIG. 2B. This signal is read by the scan converter IO at a timing described later, converted into a standard television signal, and then supplied to the arithmetic circuit 12.

In the next scanning period, the control circuit 14 switches the switch 3.7 to the position shown by the broken line in FIG. A chirp pulse is generated and supplied to the transmitting circuit 2 via the switch 3.

The transmitting circuit 2 is driven by the control circuit 14 to supply the ultrasonic transducer 1 with a down-chirp pulse whose ultrasonic energy is different from the up-chirp pulse (for example, smaller than the up-chirp pulse), and generates ultrasonic waves. Vibrator 1
transmits a down-chirped pulse into the subject. Note that the up-chirp pulse and the down-chirp pulse transmitted from the ultrasonic transducer 1 are set so that they have the same frequency spectrum although they have different ultrasonic energies.

Next, the ultrasonic transducer 1 receives the echo reflected from the subject, and supplies it as an echo signal to the down-chirp compression circuit 9 via the receiving circuit 6 and switch 7, as in the case of scanning, and pulses it. Compression is performed, and the resulting signal is read by a scan converter 11 at a timing synchronized with the scanning, converted into a standard television signal, and then supplied to an arithmetic circuit 12.

The arithmetic circuit 12, which is supplied with the standard television signals read out synchronously for each up-chirp and down-chirp scanning period, compares and calculates these signals and calculates the echo for the energy of the transmitted ultrasonic chirp pulse. A parameter related to signal dependence, for example, a nonlinear parameter representing the degree of change in the echo signal with respect to the pulse drive voltage, is determined and supplied to the display device 13, where the nonlinear parameter is signal-processed and corresponds to one ultrasound scanning line. This is visually displayed on the monitor screen as an ultrasound image.

By the way, in conventional devices that diagnose tissue properties from changes in echo signals by changing the energy of the transmitted ultrasound, the diagnosis for one ultrasound scanning line is performed based on the signal obtained by multiple ultrasound scans. Since the data is acquired, the time required for diagnosis is several times that of normal B-mode diagnosis (in B-mode diagnosis, one ultrasound scan is performed per scanning line), so the scanning cycle is shortened. In order to shorten the overall diagnosis time, it is necessary to increase the transmission rate. However, when the transmission rate is increased, among the echoes transmitted during a certain scan, echoes from distant points reach the ultrasound probe. The next scan starts before the arrival of the ultrasound image, and in this scan, the echoes from the distant point in the previous scan are received and become noise, making it impossible to obtain a high-quality ultrasound image, which reduces the overall diagnosis time. It was not possible to shorten the time to the same level as normal B-mode diagnosis.

On the other hand, in this embodiment, the up-chirp and down-chirp are switched for each successive scan, so that, for example, an echo signal reflected from a distant point in a certain scan in which an up-chirp pulse is transmitted will be transmitted in the next scan. Even if the wave is received, down-chirp compression is performed in the next scan, so the chirp waveform is different, so it is not compressed properly and does not appear in the image signal. Therefore, even if the transmission rate is increased to shorten the diagnosis time, high-quality ultrasound images with less noise can be obtained, and real-time performance is improved.

Furthermore, by switching between up-chirp pulses and down-chirp pulses, which have different ultrasound energies but the same frequency spectrum, for each successive scan, the properties of the ultrasound waves that should be used as a reference during diagnosis are improved. There is no change, and the tissue properties within the subject can be diagnosed with extremely high accuracy.

FIG. 3 is a block diagram showing the configuration of a second embodiment of the ultrasonic diagnostic apparatus according to the present invention, and the same reference numerals are used for the same parts as in the first embodiment. The difference between this second embodiment and the first embodiment is that a delay circuit 20 that delays one scanning period after one of the chirp compression circuits 8 and 9 (down chirp compression circuit 9 in this example) is provided, and the output signals of the up-chirp compression circuit 8 and the delay circuit 20 are sent to the arithmetic circuit 12.
, and the output signal of the arithmetic circuit 12 is supplied to the display device 13 via the scan converter 10, but the rest is the same as the first embodiment.

In this second embodiment, the downchirp compression circuit 9
The compressed echo signal output from the delay circuit 20
Since the signal is delayed by the scanning period and is supplied to the arithmetic circuit 12,
The timing is synchronized with the immediate supply of the output signal of the up-chirp compression circuit 8 to the arithmetic circuit 12. Similar to the first embodiment, the arithmetic circuit 12 determines the nonlinear parameters described above based on these output signals and supplies them to the scan converter 10, where the signals are converted to standard television signals and then processed by the display device 13 to produce ultrasonic waves. Visually displayed as an image.

According to the second embodiment, the same effects as the first embodiment can be obtained, and the required number of scan converters can be reduced from 2 to 1.
By reducing the number of ultrasonic diagnostic devices to 1, it is possible to achieve miniaturization and cost reduction of the ultrasonic diagnostic apparatus.

FIG. 4 is a diagram showing a third embodiment of the ultrasonic diagnostic apparatus according to the present invention, and here only the parts changed from the first embodiment, that is, the transmission control section are shown. The transmitting circuit 30 has a D/A
Converter 31, chirp pulse generation ROM 32,
Up/down counters 33 are connected sequentially, and the transmitting circuit 30 and up/down counter 33 are connected to the control circuit 34.
Configure it to be driven by.

The up/down counter 33, which is instructed by the control circuit 34 to switch between up counting/down counting and start counting when a chirp pulse is generated, supplies the corresponding up counting/down counting as an address input to the chirp pulse generation ROM 32, Upon receiving this, the chirp pulse generation ROM 32 outputs the chirp pulse waveform data corresponding to the address input to the D/A converter 31, and this data is sent to the converter 3.
1, it is converted into an analog signal and supplied to the transmitting circuit 30. The transmitting circuit 30, which has been supplied with data corresponding to one cycle of chirp pulses in this way, performs amplification (for example, power amplification) under the control of the control circuit 34 (for example, drive voltage control), and transmits the data to the ultrasonic transducer. 35 to transmit a chirp pulse inside the subject. Note that when switching between up chirp and down chirp, the control circuit 34 uses different driving voltages to make the ultrasonic energies of the two different, but in this case, the control circuit 34 uses the chirp pulse generation ROM 32 so that the frequency spectra of both are the same. (This setting is for example JP-A-62-23336.
(See No. 9).

According to the third embodiment, in addition to obtaining the same effect as the first embodiment, one chirp pulse generation circuit can selectively generate up-chirp pulses and down-chirp pulses, so that the circuit The cost of the ultrasonic diagnostic apparatus can be reduced by simplifying the process.

FIG. 5 is a diagram showing a fourth embodiment of the ultrasonic diagnostic apparatus according to the present invention, and like the third embodiment, only the transmission control section, which is a changed part from the first embodiment, is shown. In this fourth embodiment, instead of using the chirp pulse generation ROM 32 of the third embodiment, an R port M40J for up chirp pulse generation is used.
and the connection point of the parallel circuit of the down chirp pulse generation ROM 41 is connected to the counter 42, and the ROM 40.
A switch 43 connected to the output end of the D/A converter 31 and switched by the control circuit 24 is configured to be connected to the D/A converter 31.

The counter 42, which is instructed by the control circuit 34 to start counting when a chirp pulse is generated, supplies the count as an address input to the ROM 40.41.

At this time, the switch 43 is switched by the control circuit 34 to either up chirp or down chirp, so the data output of only one of the ROMs 40 and 41 is selected and supplied to the D/A converter 31. .

As a result, the waveform data of the up-chirp pulse and the down-chirp pulse stored in the up-chirp pulse generation ROM 40 and the down-chirp pulse generation ROM 41, respectively, are made to have different wave height values in order to make the ultrasonic energies different. If the frequency spectra are set appropriately so that they are the same, the same effect as in the third embodiment can be obtained, and the control circuit 34 can control the drive voltage of the transmitting circuit 30 and command up/down counts to the counter. is no longer necessary, and the circuit can be further simplified.

In addition, in the fourth embodiment, if the ROMs 40 and 41 are unified into one ROM having the same storage capacity as the total amount thereof, and the read address control for up-counting/down-counting of the counter 42 is performed, the transmitting circuit in the third embodiment This is similar to the case where the drive voltage control of No. 30 is not performed, and the circuit can be further simplified with respect to the third embodiment.

〔Effect of the invention〕

As mentioned above, in the ultrasonic diagnostic apparatus of the present invention,
Pulse compression is performed by switching between an up-chirp pulse and a down-chirp pulse whose energy differs from that of the up-chirp pulse. Based on the comparison of the obtained signals, the parameters regarding the dependence of the echo signal on the energy of the transmitted ultrasonic pulse are determined. This makes it possible to vary the energy of the up-chirp pulse and the down-chirp pulse without changing their frequency components, making it possible to obtain parameters representing the nonlinear characteristics of the tissue within the subject with higher accuracy.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the configuration of the first embodiment of the ultrasonic diagnostic apparatus according to the present invention, FIGS. 2A to 2C are waveform diagrams for explaining the operation thereof, and FIG. FIG. 4 is a block diagram showing the configuration of the second embodiment of the diagnostic device; FIG. 4 is a block diagram showing only the changes from the first embodiment in the configuration of the third embodiment; FIG.
FIG. 2 is a block diagram showing only the portions of the configuration of the embodiment that are changed from the first embodiment. 1... Ultrasonic transducer 2... Transmission circuit 3.7.
...Switch 4...Up chirp transmitter 5...Down chirp transmitter 6...Receiving circuit 8...Up chirp compression circuit 9...Down chirp compression circuit 10, 11...Scan Converter 12...Arithmetic circuit 13...Display circuit 14...Control circuit 20...Delay circuit 30...Transmission circuit
31...D/A converter 32...Chirp pulse generation ROM33...Up/down counter

Claims (1)

[Claims] 1. In an ultrasonic diagnostic device that transmits an ultrasonic chirped pulse into a living body, receives the echo signal, and processes the signal obtained by pulse-compressing the echo signal to display an ultrasonic image. , a transmitting means that switches and transmits an up-chirp pulse and a down-chirp pulse whose energy is different from the up-chirp pulse, and up-chirp compression and down-chirp compression of the echo signal corresponding to the transmission of the up-chirp pulse and the down-chirp pulse. pulse compression means for performing chirp compression; and calculation means for calculating a parameter regarding the dependence of the echo signal on the energy of the transmitted ultrasonic chirp pulse based on a comparison of the signals obtained by the up-chirp compression and the down-chirp compression. An ultrasonic diagnostic device characterized by comprising: