DE3413095A1 - Method and device for processing ultrasonic data - Google Patents

Abstract

In a sector scanner for medical ultrasonic examinations, the scanning beam of the ultrasonic transducer (11) is pivoted either mechanically or electronically. During the reading out of the vector data obtained in polar coordinates and written into the frame buffer (13), problems occur which influence the image quality of the image read out. This is due to the fact that addressable and non-addressable storage spaces (2 and 2u) exist in the frame buffer (13), the non-addressable storage spaces (2u) supplying values which were not measured during the representation on an image reproduction device (35). A method is specified in which, when the vector data supplied by the ultrasonic transducer (11) are written into the frame buffer (13), a coding information is stored at the same time in a second memory (15), the addresses of which are permanently allocated to those of the frame buffer (13). During the line-by-line reading-out of the image, the coding information is used for determining whether the values located at each individual storage space in the frame buffer (13) are attributable to an actually measured ultrasonic echo signal. If this is so, the relevant value is forwarded to the image reproduction arrangement (35). If not, the forwarding of the relevant value of the non-addressable storage space (2u) is prevented. A device for carrying out the method is also specified. <IMAGE>

Description

Siemens Aktiengesellschaft Our reference Berlin and Munich VPA IftP 3 1 2 * i QE

Method and device for processing ultrasound data

The invention relates to a method for processing vector data occurring in polar coordinates along a Ultrasonic echo line and its representation on a display device in Cartesian coordinates, with the individual vector data occurring in polar coordinates are written to predetermined first storage locations and are then read line by line on the picture display device. The invention also relates to a Device for carrying out the method with an image memory with a first number of first memory locations in matrix form, which is used to record vector data of an ultrasonic echo line in polar coordinates is connected to an ultrasound head, and to an image display device connected downstream of the image memory.

The so-called sector scanner is widely used in the field of medical ultrasound examination technology.

In the case of the mechanical sector scanner, an ultrasonic transmitter-receiver transmitter is used around its longitudinal axis and. panned here, and at the electronic sector scanner an array of ultrasonic transmitter elements is controlled by delay elements with regard to its transmission and reception behavior electronically "panned". During the pivoting process are in each case Pivot angles emitted ultrasonic waves that are at interfaces in the body of a patient to be examined are reflected and then received again. In this form of image acquisition by a sector scanner

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the sound waves received along an ultrasonic echo line are defined as vector data by polar coordinates. For display on a screen, however, an image memory is required which has a matrix form and is line by line is read out. Polar coordinates must therefore be converted into Cartesian coordinates. The need to represent polar coordinates in Cartesian coordinates poses problems that can strongly influence the image quality of the read image.

The present invention is based on the knowledge that there are addresses in the Cartesian image memory which are not described by the polar vectors received along the ultrasonic echo lines can. Addressable and non-addressable storage locations exist in the image memory. The present invention is also based on the knowledge that the reading out and display of the contents of non-addressable Storage space has a negative effect on image quality.

The object of the invention is to provide a method of the type mentioned at the beginning for processing polar coordinates to indicate the occurring signals, for which the influence of the non-addressable ones read out with line-by-line reading Memory spaces of the image memory is reduced to the image quality. Furthermore, there is the task specify a device for performing the method.

In a method of the type mentioned at the outset, this object is achieved according to the invention in that

a) that the first memory locations are assigned second memory locations in a fixed relationship,

b) that in a first process step the information content of the second memory locations is complete is deleted,

c) that in a second step, which occurs at the same time as the writing in polar coordinates Vector data takes place on the first storage locations, all those second storage locations that are in are addressable with respect to the vector data to be read in, assigned coding information be, and

d) that in a third process step only the information content of those first memory locations that correspond to the second memory locations occupied by the coding information are assigned, are used for display on the picture display device «

A device for carrying out this method is characterized according to the invention in that the image memory a background memory is assigned to which a second number of second memory locations in matrix form and in which coding information simultaneously with the writing of the vector data in the image memory The statements about the addressability or non-addressability of the first memory locations can be inscribed contained in the image memory.

In an advantageous embodiment of the method, each time it is found that the background memory is not occupied with the coding information, the image display device again the vector data of the previous memory address. Instead of the vector data of the previous memory address averaged values can also be selected, e.g. that

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arithmetic mean between the content of the last addressable memory location and the content of the next addressable memory location.

The improvement in the image quality of the reproduced ultrasound image comes about because the contents the non-addressable memory locations, which inevitably cannot contain any measured echo data, and normally contain undesired information, not used to form the ultrasound image will. These stored values are preferably not forwarded during processing.

Further advantages of the method and the device emerge from the description of the following figures in FIG Connection with the subclaims. Show it:

Fig. 1 shows the representation of a Cartesian coordinate system of an image memory with individual Matrix points and the representation of a number of "polar vectors" each along Ultrasound echo lines have been obtained,

FIG. 2 shows an enlarged image section from FIG. 1, and

3 shows a basic circuit diagram of a device for suppressing non-addressable Matrix points in the image memory according to FIG. 1. 30

In Figure 1 is a Cartesian coordinate system 1 with associated matrix points 2 and a number of lines 3 and Column 5 shown. The starting point for ultrasonic transmission pulses is located at a point P of the coordinate system 1. The ultrasonic transmission direction is around one

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Central axis Z can be swiveled within the illustrated angular range &. A number of polar vectors 7, which symbolize the received ultrasonic waves, are shown within the angular range Oo. Vector data (not shown) that describe the reflection behavior along the relevant ultrasonic echo line arise along each line.

FIG. 2 shows an enlarged illustration of a section of FIG. 1 with a single polar vector 7a. Becomes the ultrasonic wave emitted along the direction of the polar vector 7a at an interface reflected, the depth and intensity of the echoes are determined by the ultrasonic receiver. The storage of the Intensity occurs at that address in coordinate system 1 whose matrix point 2a is the true location, so the depth of reflection that comes closest. Figure 2 shows possible, i.e. addressable, matrix points 2a for the polar vector 7a shown there. The other matrix points 2 cannot be occupied by the polar vector 7a.

As can be seen from Figure 1, in the upper half of the coordinate system 1 are all matrix points 2, the lie within the sector spanned by the polar vectors 7, addressable. In the lower half of the However, coordinate system 1 exist within the scanned sector matrix points 2u, which are between two adjacent polar vectors 7 and are so far removed from these that they are not as their possible addresses come into question. A number of non-addressable matrix points 2u thus exist for each polar vector 7. Ever The further away the data is from the origin point P, the more likely it is that the non-addressable occurrence will occur Storage spaces.

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Reading out an image memory, the storage locations of which are built according to a Cartesian coordinate system 1 is done line by line. When reading out, the addressability of the matrix points 2 is not taken into account taken, nor whether there is meaningful content in the non-addressable matrix points 2u or not. For reasons of principle, a measured value cannot be saved in these memory locations. However, as tests carried out have shown, this leads to an impairment of the image quality.

Figure 3 shows a schematic representation of a device with which the influence of the non-addressable Matrix points 2u can be switched off. From an ultrasonic transducer 11 to an electronic or mechanical sector scanner, the data of the individual polar vectors 7 arrive via a data channel 12 in an image memory 13. The image memory 13 is used for intermediate storage; it is read line by line. He can e.g. store an 8-bit word per address or memory location. The specified number of storage locations is referred to here as the first number of first storage locations. A background memory is assigned to this image memory 13 15 with a second number of second storage locations. The assignment is made in a fixed relation, i.e. every first memory location corresponds exactly to a defined second memory location. Preferred the number of both types of storage space is the same. The background memory 15 can e.g. Partial memory of the image memory 13 in which all last bits of the addresses of the image memory 13 are written be realized. The information of the polar vector 7, which arrives in the image memory 13, can then be used for all Vector data are only 7 bits each. In principle, the bit depth of the background memory 15 can also be a lot higher than 1 bit, e.g. to deliver special calculation codes for each data value.

The image memory 13 is in the usual way of a Address multiplexer 17 controlled. The address multiplexer 17 is connected on the input side to a control address logic 19, which also controls a coding device 21. The control address logic 19 is in turn on on the input side a vector control 22 is connected, which is connected to the ultrasonic transducer 11. The coding device 21 acts on the background memory 15.

A second data channel 23 leads from the image memory 13 to a data register 25 “The background memory 15 is connected to a decoder 29 via a signal line 27. The decoder receives 29 via the signal line 27 the 1-bit information from the background memory

15. The 7-bit long information data of the individual memory addresses are stored on the second data channel 23 of the image memory 13 is transferred to the data register 25. Another signal line 31 leads from the decoder 29 to the data register 25. A third data channel 33 leads from the data register 25 to an image processing and display arrangement 35. A sector image is shown on their screen »

The method by which the device operates is as follows; When the device is switched on, or when a control element (not shown) is switched to the "sector scanning" operating mode, the information content of the background memory 15 is completely erased, for example set to zero.
30th

The vector control 22 coordinates the emission of the sound waves from the ultrasonic transducer 11 and the control address logic 19, with the help of which the ultrasonic echo data located on the data channel 12 have their correct addresses received in the image memory 13 allocated. For this purpose there is between the image memory 13 and the control address logic

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the address multiplexer 17 switched on. At the same time with the assignment of the ultrasound echo data of the data channel 12 to the image memory 13 is carried out by the control address logic 19 the task of writing a coding bit, e.g. the number 1, to all those addresses in the background memory 15 whose assigned addresses are written in the image memory 13, the incoming ultrasound echo data. If, for example, the number 0110101 is written to memory location No. 221 of image memory 13, coding bit 1 is thus written into memory location 221 of background memory 15 at the same time. The coding bits are set in the background memory 15 via the erase coding device 21.

This process of writing the ultrasonic echo data into the image memory 13 and setting it at the same time the coding bits in the background memory 15 are repeated as long as ultrasound echo data are for processing queue. The writing of both the ultrasonic echo data in the image memory 13 as well as the coding bits in the background memory 15 takes place independently of the im the following explained read-out process from the two memories 13, 15. It should be emphasized that at all of the Storage locations of the background memory 15, in their assigned storage locations of the image memory 13 no word is entered, the zero set at the beginning of the procedure remains.

The image memory 13 and the background memory 15 assigned to it are read out line by line at the same time. As mentioned, the two memories 13, 15 can be a single 8-bit deep memory the last (i.e. eighth) bit is provided for receiving the coding information. 7 bits then remain Depth in the actual image memory 13 for receiving the

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Ultrasonic echo image data. When reading out the image memory 13, the 7-bit word is now one of each memory location via the data channel 23 to the data register 25. At the same time, the Connecting line 27, the eighth bit, that is to say the content of the background memory 15, is routed to the decoder 29. Above The connection line 31 is the data register 25 with the information as to whether the data is on the data channel 23 Coding bit 1 was assigned to the data or not. If this is the case, the data register conducts 25 the data of the data channel 23 on to the data channel 33, from which it is transmitted to the image display device 35 reach. If the eighth bit stored in the background memory 15 does not have the coding bit, the data register is effective 25 as a closed gate and prevents the continuation of the data from the data channel 23 to the data channel 33. The data register 25 is thus to be regarded as a gate circuit.

In an advantageous embodiment of the method for operating the device, if there is no coding bit is present in the decoder 29, the content of the data register is repeatedly routed to the data channel 33. It means that in the case of a non-addressable storage space in the image memory 13 of the image display device 35 again the same information, namely the information of the previously queried address in the image memory 13, is supplied will.

Alternatively, an average of two Memory contents are calculated and forwarded to the image display device 35. For example, if a non-addressable memory address the arithmetic mean can be formed between the memory contents, the one on the last addressable memory address

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was present, and the memory content that is stored on the next addressable memory address or is saved.

The image display device 35 in the device according to FIG. 3 only ever receives those data which were actually created in the ultrasonic transducer 12. The disturbing influence of the memory contents non-addressable matrix points are eliminated. There is such a considerable improvement in the Picture quality.

11 claims
3 figures

Claims (12)

Claims ( Iy method for processing vector data occurring in polar coordinates along an ultrasound echo line and for displaying it on an image display device in Cartesian coordinates, the individual vector data occurring in polar coordinates being written to predetermined first memory locations and then read line by line on the image display device, characterized in that a) that the first memory locations are assigned second memory locations in a fixed relationship, b) that in a first process step the information content of the second memory locations is completely deleted will, c) that in a second step, which occurs at the same time as the writing in polar coordinates Vector data on the first storage locations takes place, all those second storage locations that are related can be addressed to the vector data to be read in, are assigned coding information, and d) that in a third process step only the information content of those first memory locations that have the second memory locations occupied by the coding information are assigned, are used for display on the picture display device. 2. The method according to claim 1,. characterized in that when the Reading out one of the first memory locations shows that its assigned second memory location is not - M - VPÄ 8% P 3 1 24 DE the coding information is occupied, the image display device again the vector data of the previous one the first memory location, the assigned second memory location of which was addressable. 5 3. The method according to claim 1, characterized in that when the Reading out one of the first memory locations shows that its assigned second memory location is not the coding information is occupied, the picture display device supplied v / ground averaged vector data. 4. The method according to claim 3, characterized in that j that the averaged Vector data from the preceding and following vector data of the addressable second memory locations allocated first memory locations are formed « 5. The method according to any one of claims 1 to 4, characterized in that the Coding information is a single coding bit » 6. Apparatus for performing the method according to claim 1 with an image memory with a first number of first memory locations in matrix form, which is used for receiving vector data of an ultrasound echo line occurring in polar coordinates is connected to an ultrasound head, and with a picture display device connected downstream of the picture memory, characterized in that the image memory is assigned a background memory which has a second number second memory locations in matrix form and in which simultaneously with the writing of the vector data In the image memory coding information can be written, the statements about the addressability or 34 1 3035 - ιΛ - VPA MP 3 t lh DE Non-addressability of the first memory locations in the image memory contain. 7. Apparatus according to claim 6, characterized in that between the image memory and the picture display device is provided with a gate circuit which is signal-permeable when the the second memory location of the background memory just queried is encoding information, and which is impermeable to the signal if there are none at the second memory location of the background memory that has just been queried Coding information is available. 8. Apparatus according to claim 7, characterized in that a gate circuit as a gate Data register is provided. 9. Device according to one of claims 6 to 8, characterized in that the Background memory is part of the image memory. 10. Device according to one of claims 6 to 9, characterized in that the Background memory has a depth of 1 bit. 11. Device according to one of claims 6 to 9, characterized in that the Background memory is several bits deep. 12. Device according to one of claims 6 to 11, characterized in that the image memory and the background memory has the same number of first and second memory locations, the The depth of the image memory is much greater than the depth of the background memory.