JPH0412740A - Ultrasonic beam scanning method for ultrasonic diagnostic device - Google Patents

Abstract

PURPOSE:To shortly set the image completion time of an image display and to distinctly display all the image information of the motion of the obtained affected part by executing an ultrasonic beam of a sector scan by the multistage focus control in accordance with the distance of a body to be examined, and varying the number of times of a scan in accordance with the distance of the body. CONSTITUTION:As for the number of times of a scan, conventionally, in both a short distance and a long distance, it is set to the same number of times of a scan (short distance = long distance) of 128 times, but in the case of this scanning method, for instance, at the time of the two-stage focus at the time of sector scan, when the number of times of a scan is set to (n) times and (m) times as the number of times of short distance transmission and the number of times of long distance transmission, respectively, the focus control is executed in the condition of (n)<(m), and (n)+(m)=128 times. Accordingly, even in the case an electronic scan is executed by the multistage focus in accordance with the distance of the body, the image completion time of a one-screen portion can be shortened since the number of times of a scan of one screen is set so as to be smaller than that of a long distance, in a short distance, by which an image display can be executed without lowering a frame rate.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an ultrasonic diagnostic apparatus that transmits and receives an ultrasonic beam by electronic scanning such as sector scanning, convex scanning, or arc scanning, and particularly to an ultrasonic diagnostic apparatus that transmits and receives an ultrasonic beam by electronic scanning such as sector scanning, convex scanning, arc scanning, etc. The present invention relates to an ultrasound beam scanning method for an ultrasound diagnostic apparatus that performs focus control accordingly and displays image information from a received reflected wave beam.

[Prior Art] In the medical field, conventionally, an ultrasonic diagnostic apparatus transmits and receives an ultrasonic beam to the affected area of a subject by sector scanning, convex scanning, or arc scanning.
Diagnosis of affected areas by displaying images of reflected wave beams is widely used.

In particular, in this type of ultrasonic diagnostic apparatus, for example, in one-step focusing according to the subject distance during sefter scanning, the number of ultrasound beam scans is 128, as shown in Figure 2. .

Therefore, in this case, when displaying an image, the time to complete the image can be kept within one frame time of the CRT in television scanning without any problem, and as a result, the image of the movement of the affected area obtained from the received signal can be displayed. Information can be displayed clearly in images without reducing the frame rate.

Further, FIG. 3 shows another example in which two-step focusing is performed to increase the object distance during sector scanning.

In other words, in the case of this two-stage focus, the second
Compared to the one-stage focus at a single distance shown in the figure, two-stage focus control is performed for when the object distance is short and when the object is long.

The number of times the sector scan is performed is, for example, the same 128 times as described above for both short distance and long distance.

Therefore, since focus control of the ultrasonic beam is performed according to the distance to the subject, there is an advantage that images of, for example, two parts of the subject that are different in distance can be displayed with relatively high accuracy.

[Problem to be solved by the invention H However, such multi-stage focusing, that is,
In the case of the two-stage focus shown in Fig. 3, for example, transmission is performed 128 times for each of the two-stage focus for near and far distances, so it takes longer than the time required to display image information on the television screen, for example, a CRT. However, the disadvantage was that it took a long time to complete the image.

For this reason, in the case of this two-step focus, although it has the above-mentioned advantages, there is a problem that the frame rate on the image display is lower than in the case of the one-step focus. There was a drawback that the movement of the entire subject part could not be displayed accurately as an image.

Purpose of the Invention The present invention has been made in view of the above-mentioned conventional problems.The purpose of the present invention is to achieve a short complete image without reducing the frame rate as in single-step focusing, even during multi-step focusing by electronic scanning of an ultrasonic beam. An object of the present invention is to provide an ultrasonic beam scanning method for an ultrasonic diagnostic apparatus that can display images over time.

[Means for Solving the Problems] In order to achieve the above object, according to the present invention, an ultrasonic beam is electronically scanned in a predetermined range toward a subject, and the beam interval changes depending on the distance to the subject. a focus control step of controlling the focus of the ultrasonic beam by setting the focus of the ultrasonic beam in at least two steps or more according to the distance of the object; The method is characterized by comprising a scanning number setting step of changing the number of times the beam is scanned depending on the distance of the object.

[Function] With the above configuration, according to the ultrasonic beam scanning method of the ultrasonic diagnostic apparatus according to the present invention, the number of scans such as sector scan, convex scan, arc scan, etc. can be adjusted according to the object distance. Can be set.

In other words, in the case of two-step focusing, for example, the number of scans for near and far distances is not short distance - far distance, but short distance and long distance (or in the case of arc scanning, short distance > long distance).
It can be set so that the relationship is as follows.

In this way, when displaying image information from the obtained reflected wave beam, the ultrasound beam is focused in at least two steps or more and the number of scans is set according to the object distance,
Compared to the case of one-stage focus, the complete image display time per screen can be set shorter than the frame time times the number of focus stages in television scanning.

[Embodiments] Hereinafter, preferred embodiments of the present invention will be described based on the drawings.

FIG. 1 is a schematic diagram of a case where two-step focusing is performed in an ultrasound beam scanning method of an ultrasound diagnostic apparatus according to the present invention.

Note that the same members as in FIGS. 2 and 3 of the conventional example described above are given the same reference numerals, and the explanation of the structure and operation will be omitted below.

The characteristic feature of the present invention is that the sector-scanning ultrasound beam is controlled in multiple stages according to the object distance,
The reason is that the number of scans is changed depending on the distance to the object.

As a result, the time required to complete the image display can be set shorter than in the past, and all the obtained image information of the movement of the affected area can be clearly displayed.

Hereinafter, the basic principle of the scanning method using two-step focusing of this embodiment will be explained using FIG. 1.

In the figure, the difference from the two-stage focus scanning method shown in FIG. 3, which shows the conventional example described above, is that the number of scans is reduced at short distances and increased at long distances.

That is, conventionally, the number of scans was set to the same number of scans of 128 times (near distance - long distance) for both short distance and long distance, but in this embodiment, the total number of scans is 128 times, The number of scans is set differently depending on the distance of the object, so that the distance is short and the distance is far.

Specifically, for example, in the case of two-step focusing during sector scanning, if the number of scans is n times for short-distance transmission and m for long-distance transmission as shown in FIG. 1, then n<m
, n+m=128 times.

In other words, 128 times of transmission when using two-step focus is n<m
By setting the above conditions, the transmission and reception of the short distance focus with a small image display area was made n times, and the transmission and reception of the long distance focus was made m times.

Next, we will discuss the specific sector scanning method of this embodiment in the fourth section.
This will be explained in detail using FIGS.

FIG. 4 is a circuit diagram of an ultrasonic diagnostic apparatus to which the scanning method of the present invention is applied, and FIG. 5 is an explanatory diagram of its sector scanning operation.

In FIG. 4, the ultrasonic diagnostic apparatus of this embodiment includes a CPU10 as a scan number setting step for setting the number of scans of the ultrasound beam according to the object distance, and a focus control step for controlling the focus of the ultrasound beam. The transmitting/receiving unit 14 scans the ultrasonic beam in a predetermined range by sector scanning, convex scanning, or arc scanning and transmits and receives the waves.

That is, the wave transmitting/receiving section 14 includes a wave transmitting circuit 14A and a receiving circuit 14B, and transmits and receives an ultrasonic beam using the probe 16, for example, by sector scanning.

The CPU 10 sets the number of scanning lines of the ultrasonic beam, that is, the number of times of scanning, and actually performs scanning by thinning short-distance scanning lines with respect to long-distance scanning lines by software. There is.

Therefore, the CPU 10 first sends out an address in order to determine the number of scans of the ultrasonic beam. Of course, the number of near and far distance scans n determined here
, m are set to the number of times depending on the object distance.

That is, in this embodiment, the address given at the stage of the CPU 10 is controlled by the software of the CPU 10 to thin out the scanning lines shown in FIG.

A desired sector scan is performed in nl.

Then, the transmission timing section 12 outputs a predetermined transmission pulse using the corresponding delay data based on the sent address.

Here, this transmission pulse is subjected to focus control according to the subject distance of near and far distances, and is a signal whose number of scans is set to be changed depending on the subject distance.

As a result, in the wave transmitting/receiving section 14, the wave transmitting circuit 14A
The above-mentioned transmission pulse is inputted and sent as an excitation pulse to the probe 16 which transmits and receives an ultrasonic beam to and from the subject.

Therefore, in the probe 16, the transducer within the probe is excited based on the excitation pulse, and thereby the sector scanning of the ultrasonic beam is determined by the CPU 10 and the transmission timing unit 12. Scanning is performed toward the subject using a predetermined number of scans and focus control.

Then, the reflected wave reflected from the desired subject part is input to the receiving circuit 14B in the wave transmitting/receiving section 14,
This receiving circuit 14B performs signal processing such as phase matching of the reflected wave, and sends it to the DSC 18 as a received signal.

The DSC 18 performs data conversion on the input received signal to display an image on a television screen, and outputs an image signal as an analog signal.

Therefore, on the CRT monitor 20, image information of a desired part of the subject is displayed based on the image signal, and as described above, by repeating a series of scanning control operations, for example, 128 times, ultrasound waves of the affected part of the subject are displayed. You can get the image.

The image display state on this CRT monitor 20 is as follows.
The number of scanning lines will be displayed in accordance with the object distance described above.

Next, a specific example of the number of sector scans of the ultrasonic beam in this embodiment will be explained in detail while comparing it with the conventional example using FIG.

Fig. 5(a) is a schematic diagram of sector scanning with one-step or two-step focusing, representing near-distance scanning n and long-distance scanning m, and Fig. 5(b) to (d) depict the screen. FIG.

That is, FIG. 5(b) shows the case when the conventional one-step focusing is performed, FIG. 5(c) shows the case when the conventional two-step focusing is performed, and FIG. This is a case where two-step focusing is performed.

Here, if the number of scans is 128 times, which is equivalent to one screen,
For example, the number of short-distance transmissions is n-42, and the number of long-distance transmissions is m-.
Assuming 86 times, as shown in FIG. 5(a), the time Tn (Tno, Tn, respectively) required for one transmission and reception at a short distance.

Tn Tn ,, Tn Tn and 2"3'12B'
127), on the other hand, the time Tm required for one transmission and reception at a long distance (T m T m
1° I Tm Tm , , Tm , Tm127 and 2° 3' 12B).

However, TnSTm has a relationship of Tn<Tm.

As a result, the scanning time t for one screen is as follows.

In other words, in the case of the conventional one-step focus for long distance only as shown in Fig. 2, the complete image time for one screen is tl - Tm x 128 ◆ 1 (1) as shown in Fig. 5 (b). becomes.

In addition, in the case of the conventional two-stage focus for short distance and long distance shown in FIG. 3, the complete image time for one screen is t 2 - T n X 128 as shown in FIG. 5 (C). + Tm x 128
ψ... (2) becomes.

Therefore, from equations (1) and (2) above, the complete imaging time for one screen in the conventional one-step focus case and in the two-step focus case is in the relationship it<tz, and as a result, the two-step focus In this case, it is understood that the time required to complete the image display for one screen is longer than in the case of one-stage focus, and the frame rate on the image display is reduced.

Therefore, in the two-stage focus shown in Fig. 1, if the number of short-distance transmissions is n-42 and the number of long-distance transmissions is m-86, the number of scans can be reduced to 128 in the image display equivalent to one screen. At the same time, as shown in Figure 5(d), the complete image time for one screen is t - Tn x 420 Tm x 86... (3),
Since Tn<Tm, the relationship is tX x tl.

Therefore, from the above equation (3), it can be seen that 1 of the CRT monitor 20
If we consider the time required to complete the image for the screen as tl, then t will not be longer than t (t1 varies depending on the depth of focus), so the two-step focus of this embodiment has a lower frame rate than the conventional two-step focus. It is understood that it does not fall.

This means that by setting the number of scans according to the object distance, as shown in Fig. 1 and Fig. 5 (d), mo, nl,
m2・m3・n4・m5・mo・n'
This was possible because a total of 128 scans were performed in the scanning order of "m12B" 127, and the number of scans n at short distances was smaller than the number m of scans at long distances to perform intermittent scanning.

As a result, in the image display on the CRT monitor 20,
The time required to complete an image for one screen can be shorter than that of the conventional two-stage focus shown in Figure 2, and the frame rate does not drop. It can be displayed accurately on the top.

In this embodiment, a case where sector scanning is performed as an example of electronic scanning is shown, but of course, convex scanning or arc scanning can also be applied in the same manner as described above.

In particular, when applied to arc scanning, two-step focusing is useful because it is possible to set the number of scans for short distances and long distances so that the relationship of short distance>long distance holds.

In addition, in this embodiment, the focus of the ultrasonic beam is set in two stages, and the number of scans is n-42 times for short distances and m-8 times for long distances.
An example is shown in which the focus is set to 6 times and 128 times for the entire scan (for one frame), but of course, the focus can also be set to 3 steps or multiple steps, and the number of scans is not limited to this. Any value can be set as long as the conditions for tl are satisfied, and the same effects and effects as described above can be obtained.

[Effects of the Invention] As described above, according to the scanning method of the ultrasonic diagnostic apparatus according to the present invention, even when electronic scanning is performed by multi-stage focusing according to the subject distance, the number of scans per screen can be reduced to a close range. Since the distance is set to less than the long distance, it is possible to shorten the time required to complete one screen, and as a result,
Images can be displayed without reducing the frame rate.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of sector scanning when two-stage focusing is performed using the scanning method of an ultrasound diagnostic apparatus according to the present invention. FIG. FIG. 3 is a schematic diagram of sector scanning when two-step focusing is performed using the scanning method of a conventional ultrasonic diagnostic apparatus. FIG. FIG. 5, which is a circuit block diagram of an ultrasonic diagnostic apparatus to which the method is applied, is an explanatory diagram of the operation of the beam scanning method using the circuit configuration of FIG. 4. 10... CPU 12... Transmission timing unit 14... Wave transmitting/receiving unit 14A... Wave transmitting circuit 14B... Receiving circuit n... Number of short distance scans m... Number of long distance scans Tn.・・One time transmission/reception time Tm at short distance...
Figure 1: Single transmission/reception time over long distances

Claims (1)

[Claims] (1) In an ultrasonic beam scanning method for an ultrasonic diagnostic device that performs focus control according to the distance of the subject, transmits and receives an ultrasonic beam by electronic scanning, and displays image information on a television screen from the resulting reflected wave beam. , a wave transmitting/receiving step in which the ultrasonic beam is scanned in a predetermined range toward the subject, and the beam is transmitted and received so that the beam interval changes according to the distance to the subject; and the focus of the ultrasonic beam is adjusted to the distance to the subject. a focus control step of controlling the focus by setting at least two steps or more according to the distance of the ultrasound beam; and a scanning number setting step of changing the number of scans of the ultrasound beam according to the distance of the object; Ultrasonic diagnosis characterized by setting at least two or more stages of focusing and the number of scanning steps according to the object distance, and setting the complete image time per screen to be shorter than the frame time times the number of focusing stages in television scanning. Ultrasonic beam scanning method of the device.