JP3392901B2 - Ultrasound diagnostic equipment - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrasonic diagnostic apparatus having an improved digital scan converter. [0002] An ultrasonic probe transmits an ultrasonic pulse from a living body into a living body, and receives echoes of the ultrasonic pulse reflected from the living body by the same or separately provided ultrasonic probe. And
2. Description of the Related Art There have been conventionally devised various ultrasonic diagnostic apparatuses capable of displaying, as a visible image, information collected from a plurality of directions in a living body by transmitting and receiving while shifting the direction of an ultrasonic pulse. In such an ultrasonic diagnostic apparatus, a sector scan type for scanning a fan-shaped area with respect to the ultrasonic probe 1 as shown in FIG. There is an apparatus that performs ultrasonic scanning in polar coordinates, such as a radial sector scanning type that scans a circular area. [0004] Such an ultrasonic diagnostic apparatus has an advantage that a wide field of view can be realized with a small probe. Particularly in vivo scanning devices, such as ultrasound endoscope, since it査run over the entire circumference of the lumen, radial sector scanning is often used. [0005] In an ultrasonic diagnostic apparatus, as a display device for displaying an ultrasonic image, a television which scans in a horizontal (X) / vertical (Y) direction and displays images by orthogonal coordinates as shown in FIG. Generally, a John monitor 2 is used. The above-described apparatus for scanning an ultrasonic wave in a polar coordinate system has a conversion unit for converting the ultrasonic wave in a polar coordinate system into a television scan in a rectangular coordinate system, and displays an ultrasonic image on a television monitor. Like that. [0006] This is because if the scanning method is converted into television scanning, a plurality of ultrasonic probes having different ultrasonic scanning methods can be switched and used for display on the same display device. This is because inexpensive, high-performance various image photographing devices (for example, video printers) and image storage devices (for example, VTRs) developed for John can be used. [0007] In order to display an image obtained by ultrasonic scanning in polar coordinates on a television monitor, it is necessary to convert the image into rectangular coordinates. Means for converting the scanning method such as the polar coordinate scanning into the orthogonal coordinate scanning is called a scan converter. As such a scan converter, a digital scan converter (hereinafter abbreviated as DSC) to which digital memory technology is applied is generally used today. A DSC converts an ultrasonic echo signal (analog signal) into a digital signal and outputs the digital signal to a television display 1.
The image data is temporarily written in an image memory made up of a digital memory having a storage capacity corresponding to a screen in accordance with an ultrasonic scanning method and read out in accordance with a television scanning method. [0009] By using such a DSC, it is possible to display an image subjected to ultrasonic scanning in a polar coordinate system on a television monitor. However, as shown in FIG. Since the interval of “b” increases as the distance from the probe or the probe increases, a portion where the image signal data is not written to a portion C between A and B, for example, occurs in the image memory. Therefore, it is necessary to generate and display interpolation data in order to fill a portion where no image signal data is written. When reading data from an image memory as such an interpolation method, two data before and after the data are read out.
Although interpolation data is created based on point data, this method has problems that accuracy is low and an unnatural image is often generated. For this reason, an attempt has been made to increase the accuracy of interpolation and realize a more natural image by interpolating based on data of four adjacent points surrounding a display pixel. FIG. 9 shows one such interpolation method, which is described in Japanese Patent Application Laid-Open No. 64-64635. The ultrasonic signal converted into a digital signal is temporarily stored in four line memories 11 to 11. 14 and the line memories 11 to 14
The four pieces of data read out simultaneously from are input to the pseudo data creation circuit 15, interpolated, and written into the image memory (image memory) 16. Line memory 11
The address converter 17 performs the read control from .about.14, the address conversion to the image memory 16, and the like. An ultrasonic signal is temporarily stored in a line memory 11 as described in Japanese Patent Application Laid-Open No. 64-64635.
In the circuit configuration in which the data is taken into the pixels 14 to 14 and interpolated and written into the image memory 16, as shown in FIG. 10, A, B, and C on the adjacent ultrasonic scanning lines surrounding the display pixel (x, y). , D, are interpolated based on the values of four data points. That is, weighting is applied to the four-point data of A, B, C and D in consideration of the distances a and b from the data numbers n and n + 1 and the distances c and d from the line numbers m + 1 and m. The calculation is performed by the pseudo data creation circuit 15,
I try to create interpolated data. By such interpolation, it is possible to obtain a natural, high-accuracy, high-quality image. However, in this conventional example, four line memories 11 are provided in addition to the image memory (image memory) 16.
In addition to the requirement of (1) to (14), a control circuit for a line memory and a control circuit for an image memory are required. Therefore, there is a problem that the circuit scale becomes large and the circuit configuration becomes complicated. The present invention has been made in view of such problems of the prior art, and the size of the DSC circuit is reduced by eliminating the need for a temporary storage means such as a line memory in addition to the image memory. It is an object of the present invention to provide an ultrasonic diagnostic apparatus which can be reduced in size and cost, and has a natural display image. An ultrasonic diagnostic apparatus according to the present invention for transmitting and receiving ultrasonic waves to and from a subject such as a living body and performing ultrasonic scanning in polar coordinates,
An A / D converter for converting the ultrasonic signal into a digital signal, and one screen among ultrasonic scanning lines to be scanned in a polar coordinate system.
First and second memories for storing one screen of digital signals corresponding to odd-numbered ultrasonic scanning lines among all the ultrasonic scanning lines to be formed .
Image memory and, among the ultrasonic scanning lines scanned by polar coordinates,
A digital signal corresponding to an even-numbered ultrasonic scanning line among all the ultrasonic scanning lines constituting one screen is stored for one screen .
Third and fourth image memories, and write addresses in accordance with the ultrasonic scanning method are generated to generate the first, second , third, and
A first address generating means for supplying the image data to an image memory;
A second address generating means for generating a read address in accordance with a television scanning method, and the first, second , third,
The second address so that data of at least four pixels surrounding a display pixel are simultaneously read from a fourth image memory.
A coordinate conversion unit that converts a read address generated by the generation unit and supplies the read address to the first, second , third, and fourth image memories; and the first, second , third, and fourth image memories. First, second , third and fourth weighting means for weighting each read signal; and means for adding the signals weighted by the first, second , third and fourth weighting means. , A D / A converter for converting the added signal into an analog signal. The first and second image memories, each of which stores one frame, store ultrasonic signals converted into digital signals alternately every other ultrasonic scanning line (for example, the first image memory). The second and third image memories are written into even-numbered ultrasonic scanning lines in the frame, and the third and fourth image memories are written into odd-numbered ultrasonic scanning lines in the frame. At least 4 surrounding display pixels from two image memories
One of simultaneous to put out read the data of the pixel. With this configuration, the nearest two or four pixels on the ultrasonic scanning line surrounding a pixel to be interpolated can be simultaneously read, weighted and interpolated. Embodiments of the present invention will be described below with reference to the drawings. 1 and 2 relate to a first embodiment of the present invention.
Shows an ultrasonic diagnostic apparatus according to the first embodiment, and FIG. 2 shows a configuration of an interpolation processing unit. In this embodiment, every other ultrasonic scanning line is written in four image memories (even numbered ultrasonic scanning lines are written in two image memories, and odd-numbered ultrasonic scanning lines are written in the other two image memories). ), Alternately write, and simultaneously read out four data (four data on two adjacent ultrasonic scanning lines surrounding the pixel to be displayed) one by one from each of these four image memories and display them by interpolation It is something to do. That is, the image memory having the storage capacity of one frame is divided into four image memories having the storage capacity of 1/4 frame (in other words, four image memories having the storage capacity of 1/4 frame). The image memory element constitutes an image memory having a storage capacity of one frame). In the ultrasonic diagnostic apparatus 21 according to the first embodiment of the present invention shown in FIG. 1, ultrasonic waves are radiated from the ultrasonic probe 22 into the living body in a polar coordinate system while slightly shifting the angle. The transmission / reception circuit 23 applies an electric pulse to the ultrasonic probe 22 to cause the ultrasonic probe 22 to emit ultrasonic waves toward the body, and amplifies and detects an ultrasonic echo received by the ultrasonic probe 22. Do the processing. A series of reflected ultrasonic signals taken out of the transmission / reception circuit 23 are sequentially sampled by the A / D converter 24 at a constant cycle and digitized. This A
The signal data digitized by the / D converter 24 are alternately written to image memories 25 and 26 and image memories 27 and 28 each having a storage capacity of 1/4 frame for every other ultrasonic scanning line ( For example, the image memories 25, 2
6, even-numbered ultrasonic scanning lines are written in the image memories 27 and 28, and so on. ). The writing of signal data to the image memories 25, 26, 27 and 28 is performed sequentially in accordance with the address signal generated by the write address generating circuit 29. Read address generation circuit 30 generates a read address for reading data from image memories 25, 26, 27, 28 according to the television scanning method. The read address is converted to polar coordinates by a coordinate conversion circuit 31 composed of a ROM in which a coordinate conversion table is written, and is given to image memories 25, 26, 27 and 28. The four data read simultaneously from the image memories 25, 26, 27, and 28 are input to the interpolation processing unit 32. The image memories 25, 26,
Data read from 27 and 28 are weighted and added. The data interpolated by the interpolation processing unit 32 is D
Is converted to an analog signal by the A / A converter 33 and the display device 3
4 is displayed. Control of the entire timing is performed by the system controller 35. The interpolation processing section 32 is configured as shown in FIG. Data read out from the image memories 25, 26, 27 and 28 are respectively assigned to weighting means 41, 42 and 4
3 and 44 are input. Weighting means 41, 42, 4
3, 44 weight the data read from the image memories 25, 26, 27, 28. The ratio of weighting by the weighting means 41, 42, 43, 44 is controlled by weighting control means 46. The weighting control means 46 comprises weighting means 41, 4
The result of adding the data output from 2, 43 and 44 is 10
Weighting control is performed so as to be 0%. Weighting means 4
1, 42, 43, and 44 can be constituted by a ROM in which a weighting table is written, or a circuit in which a bit shifter and an adder are combined. The weight control means 46 is also constituted by a ROM or the like in which a weight control table is written. It should be noted that it is sufficient for practical use if the weighting control means 46 can be weighted in steps of about 1/8. The adding means 47, 48 and 49 are provided with weighting means 41,
The data read from 42, 43, and 44 are added. When a pixel for which interpolation is not necessary, that is, a pixel in which data exists, is selected, the weight for that pixel becomes 1, and the weight for the other three pixels read out at the same time becomes 0. Existing pixels are output through. The operation of the interpolation processing section 32 will be described with reference to FIG. It is assumed that the read address generation circuit 30 selects the pixel (x, y), for example. The coordinate conversion circuit 31 calculates the angle (or the line numbers (m and m)) sandwiching the pixel (x, y).
+1)) and circumference (or data number (n and n + 1))
The nearest data A surrounding (x, y) above,
The addresses generated by the read address generation circuit 30 are converted so as to read B, C, and D from the image memories 25, 26, 27, and 28, and are provided to the image memories 25, 26, 27, and 28. Thus, the image memories 25, 26, 2
Data A, B, C, and D are read from 7, 28 and input to weighting means 41, 42, 43, and 44, respectively.
The weighting control means 46 performs weighting control such that weighting according to the distance a: b in the pixel (x, y) radial direction and the distance c: d in the angular direction is applied to each of the data A, B, C, and D (the At this time, the weighting control means 46 performs weighting control so that the result of adding the four data becomes 100%.) The data weighted by the weighting means 41, 42, 43, and 44 are added by the adding means 47, 48, and 49, respectively. As a result, the data output as the pixel (x, y) is obtained by weighting the nearest data A, B, C, and D surrounding the position of (x, y) according to the distance from (x, y). It becomes the interpolated data. When the position of a pixel to which data is to be written is selected, that pixel is output from the interpolation processing unit 32 through. According to this embodiment, no temporary storage means such as a line memory is required other than the image memory.
It is possible to reduce the size, power consumption, and cost of the ultrasonic diagnostic apparatus. Further, according to the present embodiment, four data on the ultrasonic scanning line surrounding the pixel to be interpolated are read out, weighted and averaged, so that highly accurate interpolation is possible. Next, a second embodiment of the present invention will be described. In this embodiment, alternate ultrasonic scanning lines are alternately written to two image memories (an even-numbered ultrasonic scanning line is written to one image memory, and an odd-numbered ultrasonic scanning line is written to the other image memory). And two data (two data on two adjacent ultrasonic scanning lines surrounding a pixel to be displayed) are read out simultaneously from the two image memories and displayed by interpolation. It is. At that time, interpolation is performed using two data that are not aligned on the same angle and the same circumference. In this embodiment, the image memory having the storage capacity of one frame is divided into two image memories having the storage capacity of 1/2 frame (in other words, the storage capacity of 1/2 frame is reduced). With two image memory elements,
An image memory having a storage capacity of one frame is configured). FIG. 3 shows an ultrasonic diagnostic apparatus 51 according to a second embodiment of the present invention. The configuration up to the A / D converter 24 is the same as that of the first embodiment. The signal data digitized by the A / D converter 24 is alternately written to the image memories 52 and 53 every other ultrasonic scanning line. Writing of signal data to the image memories 52 and 53 is sequentially performed according to the address signal generated by the write address generating circuit 29. Read address generation circuit 3
0 generates a read address of the image memory according to the television scanning method. The read address is converted to polar coordinates by a coordinate conversion circuit 31 composed of a ROM in which a coordinate conversion table is written, and is given to image memories 52 and 53. The data read from the image memories 52 and 53 is input to the interpolation processing unit 54. The data read out from the image memories 52 and 53 by the interpolation processing unit 54 are weighted and added to perform interpolation. The process after the D / A converter 33 is the same as in the first embodiment. The interpolation processing section 54 is configured as shown in FIG. The data read from the image memories 52 and 53 are input to weighting means 61 and 62. Weighting means 6
Numerals 1 and 62 weight the data read from the image memories 52 and 53. The ratio of weighting by the weighting units 61 and 62 is controlled by the weighting control unit 63. The weight control means 63 includes the weighting means 6
The result of adding the data output from 1, 62 is 100
% (For example, if one is weighted by 20%, the other is 80%, etc.).
The weighting means 61 and 62 can be composed of a ROM in which a weighting table is written, or a circuit combining a bit shifter and an adder. The weight control means 63 is also constituted by a ROM or the like in which a weight control table is written. In the weighting means 61 and 62, weighting is performed in steps of about 1/8 (for example, if one is weighted by 1/8, the other is 7/8, if one is weighted by 3/8, the other is 5/8). Is sufficient for practical use. The adding means 64 adds the data output from the weighting means 61 and 62. The operation of the interpolation processing section 54 will be described with reference to FIG. It is assumed that the read address generation circuit 30 selects, for example, the pixel (x, y). The coordinate conversion circuit 31 determines two data (in this case, the two data which are closest to (x, y) on the ultrasonic scanning lines m and m + 1 sandwiching the pixel (x, y), are not arranged at the same angle and on the same circumference, respectively. Are converted from the addresses generated by the read address generation circuit 30 so that A and D) are read out from the image memories 52 and 53.
Give to 2,53. As a result, the data A and D are read from the image memories 52 and 53, and the weighting means 61,
62 is input. Assuming that the ratio of the distance between the data A and (x, y) to the distance between the data D and (x, y) is, for example, 4 to 6, the weight control means 63 assigns 60 to the data A.
The weighting means 61 and 62 are weighted and controlled so that the data B is weighted by 40%. The data weighted by the weighting means 61 and 62 are added by the adding means 64. As a result, the data output as the pixel (x, y) is obtained by interpolating the data A and D closest to the position of (x, y) by weighting according to the distance from (x, y). Become. In addition,
When a position of a pixel to which data is to be written is selected, the pixel is output from the interpolation processing unit 54 through. According to this embodiment, no temporary storage means such as a line memory is required other than the image memory, so that the ultrasonic diagnostic apparatus can be reduced in size, power consumption, and cost. Further, according to the present embodiment, two data that are not arranged at the same angle and on the same circumference are read out from the ultrasonic scanning line sandwiching the pixel to be interpolated, and weighted and averaged, so that high accuracy is obtained. (In the first embodiment, since the image memory is divided into four, the four data are read out and weighted at the same time, even though the image memory is smaller than in the prior art. The scale of
There was no change from the past. In this embodiment, two image memories are used.
It is even smaller because it is only divided into two. In addition, since interpolation is performed using data that is not aligned at the same angle and on the same circumference, diagonal lines do not become jagged as in the past, and are as natural as when interpolation is performed with four data. Image). As described above, according to the present invention, two or four ultrasonic scan lines are provided in the image memory divided into two or four (in the case of four, two out of four ultrasonic scan lines). The even-numbered ultrasonic scanning lines are written in the plane image memory, and the odd-numbered ultrasonic lines are written in the remaining two image memories alternately, and so on. (Two or four data) are read out at the same time and interpolated, so that there is no need for a temporary storage unit such as a buffer memory other than the image memory, and the nearest neighbor on the ultrasonic scanning line sandwiching the pixel to be interpolated. Interpolation can be performed from data. Therefore, the scale of the DSC circuit can be reduced while high-precision interpolation is enabled, so that the size, power consumption, and cost of the high-performance ultrasonic diagnostic apparatus can be reduced.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing a configuration of an ultrasonic diagnostic apparatus according to a first embodiment of the present invention. FIG. 2 is a block diagram showing a configuration of an interpolation processing unit. FIG. 3 is a block diagram showing a configuration of an ultrasonic diagnostic apparatus according to a second embodiment of the present invention. FIG. 4 is a block diagram showing a configuration of an interpolation processing unit. FIG. 5 is an explanatory diagram showing an ultrasonic probe that performs sector scanning. FIG. 6 is an explanatory diagram showing an ultrasonic probe that performs radial scanning. FIG. 7 is an explanatory diagram showing scanning lines of a television monitor. FIG. 8 is an explanatory diagram showing that a blank pixel portion occurs in polar coordinate scanning. FIG. 9 is a block diagram showing a configuration of a row circuit for performing data interpolation using a line memory in a conventional example. FIG. 10 is an explanatory diagram of an operation of performing interpolation using data surrounding display pixels. [Description of Signs] 21 ... Ultrasonic diagnostic apparatus 22 ... Ultrasonic probe 23 ... Transceiving circuit 24 ... A / D converters 25 to 28 ... Image memory 29 ... Write address generating circuit 30 ... Read address generating circuit 31 ... Coordinate converting circuit 32 interpolation processing unit 33 D / A converter 34 display device 35 system controllers 41 to 44 weighting means 46 weighting control means 47 to 49 addition means

Claims (1)

(57) [Claim 1] Means for transmitting / receiving an ultrasonic wave to / from a subject such as a living body and performing ultrasonic scanning in a polar coordinate system, and an A / D for converting the ultrasonic signal into a digital signal Transducer and one screen of ultrasonic scanning lines scanned by polar coordinates
A first and second image memory for one screen stored odd digital signals corresponding to the ultrasonic scan line of the total ultrasonic scanning line, of the ultrasonic scan lines polar scanning, one screen Constitute
Third and fourth image memories for storing one screen of digital signals corresponding to even-numbered ultrasonic scanning lines of all the ultrasonic scanning lines, and generating a write address according to the ultrasonic scanning method. First address generation means for supplying to the first, second , third and fourth image memories; second address generation means for generating a read address according to a television scanning method; The read addresses generated by the second address generating means are converted so that the data of at least four pixels surrounding the display pixels are simultaneously read from the second , third, and fourth image memories , and the first, second , and third image memories are converted . a coordinate transformation means for supplying third and fourth image memory, the first, first, second, third our weights the second, third and fourth respective signal read from the image memory Yo
And fourth weighting means; means for adding the signals weighted by the first, second , third and fourth weighting means; and a D / A converter for converting the added signal to an analog signal. And an ultrasonic diagnostic apparatus comprising: