JPH0811119B2 - Ultrasonic beam scanning method - Google Patents

Description

The present invention relates to an ultrasonic beam scanning method capable of obtaining a high-definition diagnostic image without deteriorating the real-time property.

(B) Prior art and its problems In general, an ultrasonic diagnostic apparatus has a structure as shown in FIG. This ultrasonic diagnostic apparatus includes a linear electronic scanning type transducer 4 including a large number of transducer elements 2. The connection of each transducer element 2 of the transducer 4 is sequentially switched by a control signal provided from the controller unit 6 to the multiplexer 8. Therefore, the drive pulse generated from the pulsar 10 is applied to each transducer element 2 selected by the multiplexer 8, and thereby the selected transducer element 2 is driven to be excited and an ultrasonic beam is emitted to the subject 12. , Linearly scanned. The ultrasonic echo reflected from each part of the subject 12 is received again by each transducer element 2 of the transducer 2, and an echo signal corresponding to the received ultrasonic echo is output from each transducer element 2. . This echo signal is sent to the multiplexer 8
After being amplified by the amplifier 14 via the, the signal is digitized by the A / D converter 16 and stored in the image memory built in the digital scan converter 18. Then, the echo signal data stored in the image memory is read in synchronization with the TV scanning, converted into an analog signal by the D / A converter 20, and then output to the CRT monitor 22 to display a diagnostic image.

By the way, assuming that the number of scanning lines of the ultrasonic beam is N, the switching time of the ultrasonic scanning lines is α, the screen forming time is T, the diagnostic depth is L, and the sound velocity is C, the relationship between them is as follows. It is represented by.

N = T / (α + 2L / C) (1) = T / t (2) where t (= α + 2L / C) is the scanning time interval of each ultrasonic beam.

In the linear electronic scanning, the switching time α of the ultrasonic scanning line
Can be disregarded, so the one-screen forming time T from the equation (1) is T = tN = 2NL / C (3).

On the other hand, in performing ultrasonic diagnosis, it is sometimes desired to magnify a part of the diagnostic image and observe the site in detail. In such a case, if the number of scanning lines of the ultrasonic beam is left unchanged and the image is enlarged, the echo signal data between the ultrasonic scanning lines becomes insufficient, resulting in a rough image. In order to eliminate this inconvenience, increasing the number N of scanning lines of the ultrasonic beam is one of the countermeasures, but conventionally, the scanning time interval t of the ultrasonic beam is constant even when obtaining an enlarged image. Therefore, the one-screen forming time T is lengthened from the relation of the expression (3), and the real-time property is impaired. That is, when the real-time property is insufficient, the displayed image flickers, which makes it difficult to view the image.

Therefore, in the related art, when displaying a magnified image, the echo signal data stored in the image memory is used as shown in FIG. 4 without increasing the number of scanning lines of the ultrasonic beam itself, For example, interpolation processing is performed such as calculating an average value between scanning lines of adjacent ultrasonic beams. In FIG. 4, a solid line shows an actual ultrasonic scanning line and a dotted line shows interpolation data.

However, since the echo signal data obtained by such interpolation processing is different from the echo signal data based on the actual transmission / reception of the ultrasonic beam, the fidelity of the data is lacked and a high-definition image should be secured. I can't. In particular, the tendency becomes more remarkable as the enlargement ratio of the image increases.

The present invention has been made in view of such circumstances, and is obtained by always transmitting and receiving an actual ultrasonic beam without impairing the real-time property even when the magnification of the diagnostic image is changed. It is an object to be able to display a high-definition diagnostic image based on echo signal data.

(C) Means for Solving the Problem In order to achieve the above object, in the present invention, when a diagnostic image obtained based on transmission and reception of an ultrasonic beam is enlarged and displayed, the vertical and horizontal enlargement ratios of the diagnostic image are set. When K is set, the scanning line interval of the ultrasonic beam is set to 1 / K times before expansion according to this expansion rate, and L / K (L
By acquiring data only in the range of (diagnosis depth before expansion), and by scanning the ultrasonic beam at the speed of K times before expansion over the same entire scanning range as before expansion, real time before expansion. The feature is that the scanning line density of the ultrasonic beam is increased without impairing the property.

(D) Example An example of the ultrasonic beam scanning method of the present invention will be described below.

(I) When Obtaining a Normal Diagnostic Image Not Enlarged Display In this case, first, as shown in FIG. 1 (a), one K (4 in this example) transducer elements e
One transducer block B is configured, and a predetermined delay time is given to each transducer element e of the two transducer blocks B so that the ultrasonic beam is focused at one point. And
The ultrasonic beam is scanned while shifting each transducer block B by one transducer block B (each by four transducer elements e). Therefore, assuming that the pitch interval between the transducer elements e is d, the scanning line interval of the ultrasonic beam is kd.
(= 4d). Then, it is assumed that N (for example, 110) scanning lines are obtained when scanning is performed at the pitch interval Kd, and that one normal diagnostic image is formed in advance with this number of scanning lines N. Set it.

In addition to the above-described embodiment, the scanning line interval of the ultrasonic beam can be set to Kd (= 4d) by driving every K (four in the above example) transducer elements.

(Ii) In the case of enlarging and displaying the vicinity of the body surface For example, as shown in FIG. 2, when the diagnostic depth before the enlarging display of the diagnostic image obtained by scanning the ultrasonic beam is L, the body surface is This is a case where an image in the range from 1 to L / K (for example, L / 4) is magnified and displayed in the vertical and horizontal directions K times (= 4 times).

In this case, first, the scanning line interval of the ultrasonic beam is set to 1 / K times (= 1/4 times) that in the case where the enlarged display is not performed, in accordance with the vertical and horizontal expansion rate K. That is, as shown in FIG. 1B, one transducer block B is configured by K (four in this example) transducer elements e adjacent to each other, and each transducer of the two transducer blocks B is formed. A predetermined delay time is given to the element e so that the ultrasonic beam is focused on one point. Then, the ultrasonic beam is scanned while shifting each transducer block B by one transducer element e. Then, the scanning line spacing of the ultrasonic beam is determined by each transducer element e.
Pitch interval d. Therefore, the number of scanning lines of the ultrasonic beam for forming one screen of the diagnostic image is K times (= 4 times).
To KN (= 440).

At that time, the ultrasonic beam is moved at the speed of K times (= 4 times) before expansion over the same entire scanning range as before expansion.
Then, the scanning time interval of the ultrasonic beam is 1 / K before expansion.
(= 1/4), but since it is enough to observe the range of L / K from the body surface, there is no problem in transmitting and receiving ultrasonic waves. Therefore, assuming that the formation time of one enlarged image in this case is T ', from equation (3), T' = KN. (2L / K) / C = 2NL / C = T It becomes the same as the formation time T. That is, the real-time property is exactly the same before and after expansion. Moreover, since the number of scanning lines of the ultrasonic beam is increased by the amount by which the image is enlarged, an image with the same definition as before the enlargement can be obtained.

Similarly, in the case where an image in the range L / 2 from the body surface is enlarged and displayed twice, the two transducer elements e
It is sufficient to scan the ultrasonic beam at a speed twice as fast as that before expansion over the same entire scanning range as before expansion while shifting them one by one.

Although the above-described embodiment is for the case of performing linear electronic scanning, it can be similarly applied to the case of convex electronic scanning. In addition, in the case of sector electronic scanning, when enlarging and displaying the vicinity of the body surface, the scanning speed is set to be the same as when not enlarging and displaying, and if the scanning time interval of the ultrasonic beam is 1 / K times, real-time property is obtained. The number of scanning lines of the ultrasonic beam can be increased K times without damaging the image, so that an image having the same definition as that before the enlargement can be obtained even in the enlarged image. Also, when enlarging and displaying the focused area, set the scanning speed in the target enlarged area.
If it is set to 1 / K and the time interval for scanning the ultrasonic beam is the same after expansion, the number of scanning lines of the ultrasonic beam can be increased K times without deteriorating the real-time property. , An image with the same definition as before enlargement can be obtained. Furthermore, the present invention can be applied not only to electronically scanning an ultrasonic beam as in this embodiment, but also to mechanical scanning.

(E) Effect As described above, according to the present invention, it is possible to always display a diagnostic image based on echo signal data obtained by transmitting and receiving an actual ultrasonic beam even when the magnification of the diagnostic image is changed. Therefore, an excellent effect that a high-definition diagnostic image can be obtained and the real-time property is not impaired is exhibited.

[Brief description of drawings]

1 and 2 show an embodiment of the present invention. FIG. 1 is an explanatory view of a scanning method of an ultrasonic beam, FIG. 2 is an explanatory view of enlarged display of a diagnostic image, and FIG. FIG. 4 is a block diagram of a sound wave diagnostic apparatus, and FIG. 4 is an explanatory view of data interpolation when a diagnostic image is displayed in an enlarged manner. e ... Transducer element, B ... Transducer block.

Claims (1)

[Claims] 1. When magnifying and displaying a diagnostic image obtained based on transmission / reception of an ultrasonic beam, if the longitudinal and lateral magnifying power of the diagnostic image is K, the ultrasonic beam By setting the scan line interval to 1 / K times before expansion and acquiring data only in the range of L / K (L is the diagnostic depth before expansion) from the body surface, the ultrasonic beam is expanded before expansion. An ultrasonic beam scanning method characterized by increasing the scanning line density of an ultrasonic beam without deteriorating the real-time property before expansion by scanning at the speed of K times before expansion over the same entire scanning range. .