JPS5990555A - Multi-frequency ultrasonic photographic apparatus - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an ultrasonic imaging device17, and more specifically, the ultrasonic waves transmitted to a subject are multi-frequency waves. The present invention relates to an ultrasonic imaging device that obtains echo signals and displays images at a certain rate.

In a typical ultrasound imaging device, the center frequency of ultrasound generated by an ultrasound probe is fixed and constant. In such an apparatus, if an attempt is made to increase the depth of exploration, there is a problem in that the speed of sound within the specimen is limited and the line rate and frame rate associated with image display are reduced. This is an essential problem in line-sequential ecography.

Although it has become possible to obtain uniformly high-quality images from shallow to deep areas through frequency processing of reflected waves, there is no solution to the problem in terms of line rate and frame rate. In particular, it has been incompatible to use pulsed Doppler etc. (which requires a high line rate) and to get intimate access to deep areas with a clear view.

In view of these points, the purpose of the present invention is to scan areas with a shallow exploration depth with a high line V-) and scan deep areas with a conventional 2-in rate, and to be able to be used in combination with pulsed Doppler, etc. An object of the present invention is to provide a multi-frequency ultrasound imaging device.

In order to achieve this purpose, the present invention generates ultrasonic waves of different frequencies from an ultrasonic probe, and generates ultrasonic waves at a short distance (7). For intermediate to long distances, low frequency ultrasonic waves can be used to reduce the line rate to 1/1 of the high line rate.
This apparatus is characterized in that an image is obtained on line V- of n (,nn2), and that the transmitted ultrasonic pulses are synchronized in a 1:n relationship.

The present invention will be described in detail below using the drawings. FIG. 1 is a block diagram showing a manufacturing section of an embodiment of a multi-frequency ultrasound imaging device according to the present invention. In the figure, this is a drive circuit that monitors the camera element 20 in order to generate one ultrasonic wave at a time 10. The vibrator 20 is a broadband vibrator,
A drive circuit 10 suitable for this purpose is shown in FIG. That is, under the control of the controller 1, the pulsers 12 and 13 are energized at appropriate timing, and the drive pulses generated therefrom are passed through the band pass filter 4 for high frequencies and the band pass filter 4 for low frequencies, respectively. Only those in a predetermined frequency band are extracted through the bus filter 5 and fed to the vibrator 20 through an adder 16. FIG. 43 is a configuration diagram showing another embodiment of the drive circuit 10, in which one broadband pulser 12 is energized by the controller 11', and the controller 11 is energized by the controller 11'.
The output of the pulser 12 is taken out directly or via the high-frequency bandpass filter 14 by the switch 17 which is switched by
I try to give C. The reflected wave is received by the vibrator 20, converted into an electrical signal, and then guided to a low frequency channel and a high frequency channel in parallel. The low frequency channel is TG
A/P 3 with C (Time Ga1n Control)
1. Consists of a variable filter 32 and a processing circuit 40. The amplifier with TGC 51 appropriately amplifies the received signal while compensating for the decrease in the received signal depending on the depth of the object, in other words, depending on the elapsed time. Further, the variable filter 32 corrects for the frequency of the received signal to decrease due to the depth of the subject, differences in tissue cells, etc. The echo signal thus corrected is sent to the processing circuit 40 and subjected to normal processing such as logarithmic compression, detection, cutting of high frequency components, and amplification. On the other hand,
High-frequency channel Hubband pulse filter 55, TGC
Attachment 77 It consists of a fuse 54 and a processing circuit 50.

The amplifier 34 with TGC and the processing circuit 50 exhibit the same functions as the amplifier 31 and the processing circuit 40 of the low-frequency channel. The bandpass filter 33 is only for extracting high-frequency signals from the echo signal, and is not used.

Output V1 multiplexer 61 of processing circuits 40 and 50
The signal is selectively selected as an alternative and guided to the All converter 62, where it is converted into a digital signal and stored in the -H frame memory 63. The image data stored in the 7-frame memory 63 is read out in an order suitable for display 12, converted into analog data by a DA converter 64, and then sent to the CIIT as a video signal.
The light is applied to the display device 70, and the image is blurred in a television manner.

In addition, as a wideband camera element 20, approximately 1.5 to i, oi・
If we choose one with a band of l1fz, then we also use a pulser with at least approximately 5 to 10 R11 (one that equalizes the frequency component of z and 17, and at the same time - also a high bandpass filter 14 and 33 that For example, the width is about 3.5~:l-OMllz.Then, in the high-frequency channel, echo signals of about 3.5 hllllz or more are received and processed, and in the low-frequency channel, the echo signal is 1, about 2 h4IIZ.
Receive and process the following echo signals.

Note that the vibrator 20 is for high frequency use (for example, approximately 3.5°).
A composite type vibrator may be formed by combining a vibrator of 5 to 1.0 hiHz and a vibrator of low frequency (for example, about 1.5 to 2 MIIz) to form an annealer shape or the like.

The operation related to transmitting and receiving ultrasonic waves in such a configuration will be described next. Note that the drive circuit 10 having the configuration shown in FIG. 3 will be explained here as an example. The controller 11' generates trigger pulses at a constant period as shown in FIG. 4(A). The pulser 12 is energized by a trigger to generate a drive pulse having a frequency component of about 1.5 to 10 N411z. At this time, by selecting the switch 17, the even numbered (
2n, 2n+rei...) drive pulses remain as they are, while the odd-numbered drive pulses (2n+1...) are applied to the vibrators as only high-frequency drive pulses via the bandpass filter 14. It will be done. As a result, as shown in FIG. 4(c), the transducer 20 emits broadband ultrasonic waves (1,5 to 10 IV+irz) when an even-numbered trigger occurs, and high-frequency waves (3,5 to 10 IV+irz) when an odd-numbered trigger occurs.
1.0 MHz) ultrasonic waves are generated.

According to such wave transmission, an echo wave as shown in FIG. 4 is returned to the vibrator. This echo wave consists of the low-frequency echo wave shown in (e) in Figure 4 (the low-frequency ultrasound wave is transmitted at two trigger intervals, so the low-frequency echo wave spans two trigger periods), and the fourth echo wave. The high-frequency echo wave shown in (f) of the figure (1
(obtained for each trigger period).

In the circuit for the low frequency channel of an amplifier with TGC 31 or less, the low frequency (1,5 to 2 N11lz) shown in Figure 4 (E) is used.
d in the circuit for the high-frequency channel below the bandpass filter 33.
An echo signal based on a high frequency (3 to 10 λIIIZ) echo wave shown in (f) of FIG. 4 is processed.

According to such transmission and reception, depending on the transmission and reception of high-frequency ultrasonic waves, it is possible to probe the object twice as fast as that of low-frequency ultrasonic waves. That is, for the sector scanning plane as shown in Fig. 5, an image of the entire range is obtained in the low frequency channel,
In the high frequency channel, images of shallow areas (portions at depth e/2-t, half of the maximum exploration depth t), so-called short distances, are obtained at twice the line rate or twice the frame rate of the low frequency channel. be able to.

These two types of image data obtained at the same time are switched as appropriate by the multiplexer 61, and the data of the high frequency channel is used for short distances, and the low frequency channel data is used for deep distances, that is, for long distances. The image ' data is stored in the frame memory 63 after AD conversion.

Note that the line rate ratio between the shallow portion and the deep portion may not be 2, but may be an integer of 3 or more. Further, the ultrasonic scanning may be not only sector scanning but also linear scanning. Furthermore, instead of just acquiring an 8%-mode image, as shown in Figure 6, the entire area is captured as a B-mode image, and shallow areas are scanned at a faster 2-in rate to perform pulsed Doppler. You can also do that. In this case, the B-mode image is sufficient to be used for determining the position of the pulsed Doppler volume SV, and high resolution is not required.

-Also, polarity interleap (in which the polarity is reversed every other time for both high-frequency and low-frequency transmission waves as shown in (c) in Figure 4), and a delay line canceller as shown in Figure 7 By separating and extracting the echo signals using the 70W, it is possible to independently obtain each desired output in the low and high frequency channels, which are essentially mutually free from interference. In other words, if the two delay lines DL□ and T'11.2 in Fig. 7 are both set at 17 in the period of the trigger pulse shown in Fig. 4 (0), the echo signal passes through the amplifier AMp and becomes output 1. Regarding matching trigger pulses. From the trench output 2, the echo signals of X (every other) things further ahead and the current one are added and subtracted by adders/subtractors 71 and 72, respectively, and appear. In such a configuration, if four consecutive trigger pulses are used as a period to send out high-frequency and low-frequency transmission pulses with different polarities as shown in the table (where n is natural), output 2 will have a high Since a signal containing almost no echoes related to the frequency-transmitted pulses can be obtained, if this signal is further separated completely using a low-pass filter (not shown), it will be possible to display the signal as shown in Figures 5 and 6. It is possible to provide a seamless image to the displayed content in the wide field of view. - What is obtained at a force output of 1 is a change or difference in the echo corresponding to the high-frequency transmitted pulse, that is, a Doppler shift component. This is also accomplished by removing mixed low-frequency components using an appropriate low-cut filter (not shown) to achieve υ complete MTI' (
(moving object display) can be used as a stop signal.

As explained above, according to the present invention, shallow areas can be scanned at a high line rate, and deep areas can be scanned at a slower normal line rate. It is possible to realize a multi-frequency ultrasound imaging device that can be used in combination with the above methods, and its effects are great in practical use.

[Brief explanation of drawings]

FIG. 1 is a block diagram of main parts of an embodiment of a multi-frequency ultrasound imaging device according to the present invention, FIGS. 2 and 5 are diagrams of an embodiment of a drive circuit, and FIG. 5 is a diagram showing an example of scanning, FIG. 6 is a diagram for explaining the scanning state when used in combination with pulse toshiba, and FIG. 7 is a configuration diagram showing a part of the circuit in another embodiment of the present invention. be. 10... Drive circuit, 11... Controller, 12.
13... Pulsar, 14.15.33... Bandpass filter, 17... Switch, 20... Vibrator,
31.34...Amplifier with TGC, 32...Variable filter, 40.50...Processing circuit, 61...Multiplexer, 63...Frame memory, 70...CII
T display device. Leather 5 figure M6 figure 7 figure z le

Claims (4)

[Claims] (1) A transducer that transmits and receives multi-frequency, broadband ultrasonic waves is used. For short distances, the high line rate is transmitted using the high frequency range, and for long distances, the high line rate is transmitted using the low frequency range. A multi-frequency ultrasound image characterized in that each image can be acquired at a line rate of h/n, and the acquired image data is once stored in a frame memory and then used for image display. Device. (2) Filter means are used to generate the high-frequency and low-frequency multi-frequency ultrasonic waves and to separate the obtained multi-frequency echo signals into high-frequency and low-frequency signals, respectively. A multi-frequency ultrasound imaging device according to claim 1, characterized in that: (3) The vibrator according to claim 1, wherein the vibrator is composed of a high-frequency vibrator that excites in a high frequency band and a low-frequency vibrator that excites in a low frequency band. Multifrequency ultrasound imaging device. (4) When energizing the vibrator, polarity interleaving is performed when energizing at a high frequency and when energizing at a low frequency. 2. The multifrequency ultrasound imaging device according to claim 1, wherein reception is performed in a manner that reduces interference.