JP4067666B2 - Ultrasonic diagnostic equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an ultrasonic diagnostic apparatus, and more particularly to reduction of an influence caused by side lobes (unwanted radiation) generated in a different direction from a main beam.
[0002]
[Prior art and problems]
In the ultrasonic diagnostic apparatus, an ultrasonic beam (a transmission beam and a reception beam) is formed using a so-called electronic focus technique. When an ultrasonic beam is formed, a plurality of side lobes are generally generated in a direction different from the main beam direction. When a reflector is present on the side lobe, the reflector appears on the ultrasound image as if it is present on the main beam. Such a false image becomes a factor of deteriorating the image quality of the ultrasonic image, and reduces the accuracy of disease diagnosis. Therefore, various methods have been proposed for reducing side lobes. For example, JP-A-10-127635, JP-A-10-057374, JP-A-8-289891, JP-A-7-159520, and JP-A-6-249947 have inventions relating to sidelobe reduction. Proposed. However, there is a demand for reducing side lobes more flexibly and more accurately.
[0003]
The present invention has been made in view of the above-described conventional problems, and an object thereof is to effectively reduce side lobes in an ultrasonic diagnostic apparatus.
[0004]
[Means for Solving the Problems]
In order to achieve the above object, the present invention supports first complex signal converting means for converting a first received signal corresponding to the first beam into a first complex signal, and a second beam different from the first beam. Second complex signal converting means for converting the second received signal to a second complex signal, phase correcting means for performing phase correction on at least one of the first complex signal and the second complex signal, and after the phase correction And amplitude calculating means for calculating an amplitude signal based on the first complex signal and the second complex signal.
[0005]
According to the above configuration, the first beam and the second beam are formed simultaneously or sequentially, and the first reception signal and the second reception signal corresponding to the first beam and the second beam are converted into complex signals, respectively, and the first complex signal generated thereby And after the phase of at least one of the second complex signal is corrected, both are added. Here, the phase correction amount is set manually or automatically. If the phase correction amount is set appropriately, the side lobe is effectively reduced. That is, the phase correction amount is set so that the phase of the sidelobe component is reversed or the phase difference is 180 degrees as much as possible.
[0006]
Desirably, a correction amount setting means for variably setting a correction amount in the phase correction is included. According to this configuration, for example, the phase correction amount may be appropriately adjusted so that the influence of the side lobe is reduced while observing the display image. Although it is generally difficult to remove all side lobes (false images) over the entire screen, the side lobes can be easily reduced by the above-described method for the target portion. The determination of whether or not the side lobe can be easily made on the image by shifting the phase correction amount appropriately. That is, the portion where the luminance changes more greatly by the scanning of the phase correction amount is an image component due to the side lobe.
[0007]
When the first beam and the second beam are formed in a time division manner, the first complex signal conversion unit and the second complex signal conversion unit may be configured as a substantially single unit. The same applies to other configurations. However, when the time division method is adopted, it is necessary to provide a memory for storing the previously processed signal until the processing of the subsequent signal is completed.
[0008]
The first beam and the second beam are preferably formed adjacent to each other from the viewpoint of the spatial resolution of the image.
[0009]
Preferably, the amplitude calculating means includes an adding means for adding the first complex signal and the second complex signal after the phase correction, an absolute value calculating means for generating an amplitude signal from the added signal after the addition, including. According to this configuration, it is not always necessary to provide a plurality of absolute value calculation means.
[0010]
Preferably, weighting means for weighting each complex signal before addition of the first complex signal and the second complex signal is included. According to this weighting, the enhancement degree of phase correction can be adjusted. It is desirable that the weighting value can be adjusted according to the purpose of diagnosis.
[0011]
Preferably, the amplitude calculation means is provided for each of the first complex signal and the second complex signal after the phase correction, and performs an absolute value calculation for each complex signal to perform the first amplitude signal and the second amplitude signal. And an adding means for adding the first amplitude signal and the second amplitude signal.
[0012]
Preferably, weighting means for weighting each amplitude signal or each complex signal before addition of the first amplitude signal and the second amplitude signal is included.
[0013]
Preferably, a phase difference calculation unit that calculates a phase difference between the first complex signal and the second complex signal, and a correction amount setting unit that sets a phase correction amount based on the phase difference. According to this configuration, the correction amount can be set adaptively based on the phase difference, and the complexity associated with manual adjustment of the phase correction amount can be eliminated.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of the invention will be described with reference to the drawings.
[0015]
FIG. 1 shows a preferred embodiment of an ultrasonic diagnostic apparatus according to the present invention, and FIG. 1 is a block diagram showing the overall configuration thereof.
[0016]
The probe 10 is, for example, an ultrasonic probe that houses an array transducer composed of a plurality of vibration elements. The probe 10 is used in contact with the body surface or inserted into a body cavity. A transmission / reception circuit 12 is connected to the probe 10. A transmission signal is supplied from the transmission / reception circuit 12 to the probe 10. On the other hand, a reception signal from the probe 10 is subjected to processing such as amplification in the transmission / reception circuit 12 and then output from the transmission / reception circuit 12 to the quadrature detectors 14 and 16. . A scanning control unit (not shown) is connected to the transmission / reception circuit 12, and the direction of the transmission / reception beam is determined by the scanning control unit. The present invention can be applied to the electronic sector scanning regardless of the scanning form of the ultrasonic beam such as electronic linear scanning and convex scanning.
[0017]
In the present embodiment, two quadrature detections 14 and 16 are provided in parallel. One quadrature detector 14 receives the first received signal 100 obtained by forming the first beam. The other quadrature detector 16 receives the second received signal 102 obtained by forming the second beam. In this embodiment, two quadrature detectors are prepared in order to simultaneously form two transmission / reception beams. Of course, two beams may be formed in a time division manner. In this case, two received signals are sequentially processed using a single quadrature detector.
[0018]
Reference signals 104 for quadrature detection are input to the quadrature detectors 14 and 16. This reference signal 104 is a signal having a frequency corresponding to the transmission frequency, and reference signals having a phase difference of 90 degrees are also generated in the quadrature detectors 14 and 16, and these two reference signals are transmitted to each received signal. Will be added. Then, by extracting a signal in a specific band from the signals after addition, a first complex signal 106 corresponding to the first beam and a second complex signal 108 corresponding to the second beam are generated.
[0019]
In the present embodiment, the first complex signal 106 is input to the phase corrector 18. The phase corrector 18 is a circuit that performs phase correction on the first complex signal 106, and the correction amount is set by the correction amount adjuster 20.
[0020]
Input values and transmission / reception parameters set by the user are input to the correction amount adjuster 20, and the correction amount adjuster 20 adjusts the phase correction amount based on these values. The input value is a value that serves as a correction criterion set by the user. The transmission / reception parameter is, for example, the scanning angle θ, and the parameter is used as a correction value for the input value. For example, when the scanning angle θ is 0, the input value is output to the phase corrector 18 as it is.
[0021]
Therefore, the embodiment shown in FIG. 1 has an advantage that the phase correction amount can be basically set by the user, and for example, the correction amount can be appropriately set while viewing the displayed ultrasonic image. In this case, for example, the input value may be set by the user so that the image of the target observation site is the clearest.
[0022]
Incidentally, when the correction amount is adjusted, the image by the true echo corresponding to the main beam does not change so much, whereas the image corresponding to the side lobe changes greatly in phase, so the image quality also changes greatly. Based on such a premise, the correction amount can be appropriately adjusted manually.
[0023]
The corrected first complex signal 106 </ b> A output from the phase corrector 18 is input to the weighting circuit 19. Then, the real part and imaginary part of the complex signal 106A are multiplied by a constant coefficient β, and the weighted first complex signal 106B is input to the adder 22. On the other hand, the second complex signal output from the quadrature detector 16 is input to the weighting circuit 21. Then, the real part and the imaginary part constituting the second complex signal 108 are multiplied by a constant coefficient (1-β), and the weighted second complex signal 108B is sent to the adder 22. Yes. The adder 22 performs addition of the first complex signal 106B and the second complex signal 108B in each of the real part and the imaginary part, and outputs the complex signal after addition to the absolute value calculator 24.
[0024]
The absolute value calculator 24 is a circuit that performs an absolute value calculation on the complex signal after addition output from the adder 22. Specifically, the absolute value is obtained by executing the root operation on the square of the real part plus the square of the imaginary part. This absolute value corresponds to the envelope component of the received signal.
[0025]
The DSC (digital scan converter) 26 is a circuit that executes coordinate conversion and the like, and the frame memory in the DSC 26 stores data 114 output from the absolute value calculator 24 as tomographic image data. A tomographic image (B-mode image) composed of such data is displayed on the display 28.
[0026]
As described above, according to the embodiment shown in FIG. 1, the user can adjust and set the correction amount while actually viewing the tomographic image, and there is an advantage that a desired image with reduced side lobes can be freely constructed. . In addition, since the user-set input value is finely corrected according to the beam scanning angle or the like, the correction amount can be set more appropriately. Furthermore, if the value of the coefficient β in the weighting circuits 19 and 21 can be set by the user, there is an advantage that the degree of effect by the phase correction can be freely adjusted. In this case, if the value of β is close to 0.5, the effect of phase correction can be further increased. On the other hand, if the value is decreased, the effect can be reduced.
[0027]
Next, a second embodiment will be described with reference to FIG. In addition, the same code | symbol is attached | subjected to the structure similar to the structure shown in FIG. 1, and the description is abbreviate | omitted. In the embodiment shown in FIG. 2, two absolute value calculators 30 and 32 are provided before the adder 34, and the adder 34 performs addition in the state of the envelope signal.
[0028]
As shown in the figure, weighting circuits 42 and 44 are provided between the absolute value calculators 30 and 32 and the adder 34, and the same weighting as described above is executed. That is, the signal 122 output from the absolute value calculator 30 is input to the weighting circuit 42, the signal 122 is multiplied by the coefficient β, and the signal 122A after the multiplication is input to one input terminal of the adder 34. Has been. Similarly, the signal 124 output from the absolute value calculator 32 is multiplied by the coefficient (1-β) in the weighting circuit 44, and a signal 124 A representing the multiplication result is input to the other input terminal of the adder 34. ing. The signals 122A and 124A are added, and the addition result is sent to the DSC 26.
[0029]
Incidentally, also in the embodiment shown in FIG. 2, two beams can be formed in a time-sharing manner, and in that case, one orthogonal detector 14 and one absolute value calculator 30 may be provided. Then, the phase corrector 18 only needs to be operated on one of the received signals. Alternatively, the weighting circuit may perform β and 1-β multiplication in a time division manner, and the adder 34 may temporarily store the preceding signal in the memory and then add the next signal.
[0030]
Next, a third embodiment will be described with reference to FIG. In addition, the same code | symbol is attached | subjected to the structure similar to the structure shown in FIG.1 and FIG.2, and the description is abbreviate | omitted.
[0031]
In the third embodiment shown in FIG. 3, the phase correction amount is automatically set. That is, the first complex signal 106 and the second complex signal 108 output from the quadrature detectors 14 and 16 are input to the correction amount setting unit 40, and the phase difference between the two complex signals is calculated. The correction amount setting unit 40 calculates a phase correction amount according to the phase difference. In this case, transmission / reception parameters are taken into consideration as necessary as described above. Other configurations are the same as those shown in FIG. Therefore, according to the embodiment shown in FIG. 3, since the phase correction amount can be automatically set, there is an advantage that complexity can be eliminated as compared with the case of manual operation. As to how to set the correction amount according to the detected phase difference and transmission / reception parameter, the setting function may be appropriately determined based on experimental results.
[0032]
【The invention's effect】
As described above, according to the present invention, side lobes can be effectively reduced in an ultrasonic diagnostic apparatus.
[Brief description of the drawings]
FIG. 1 is a block diagram showing an embodiment according to the present invention.
FIG. 2 is a block diagram showing another embodiment according to the present invention.
FIG. 3 is a block diagram showing another embodiment according to the present invention.
[Explanation of symbols]
10 probe, 12 transmission / reception circuit, 14, 16 quadrature detector, 18 phase corrector, 19, 21 weighting circuit, 20 correction amount adjuster, 22 adder, 24 absolute value calculator.

Claims (7)

First complex signal converting means for converting a first received signal corresponding to the first beam into a first complex signal;
Second complex signal converting means for converting a second received signal corresponding to a second beam different from the first beam into a second complex signal;
Phase correction means for performing phase correction on at least one of the first complex signal and the second complex signal;
Amplitude calculating means for calculating an amplitude signal based on the first complex signal and the second complex signal after the phase correction;
An ultrasonic diagnostic apparatus comprising: The apparatus of claim 1.
An ultrasonic diagnostic apparatus comprising correction amount setting means for variably setting a correction amount in the phase correction. The apparatus of claim 1.
The amplitude calculation means includes
Adding means for adding the first complex signal and the second complex signal after the phase correction;
Absolute value calculating means for generating an amplitude signal from the added signal after the addition;
An ultrasonic diagnostic apparatus comprising: The apparatus of claim 3.
An ultrasonic diagnostic apparatus comprising weighting means for weighting each complex signal before addition of the first complex signal and the second complex signal. The apparatus of claim 1.
The amplitude calculation means includes
Absolute value calculation means provided for each of the first complex signal and the second complex signal after the phase correction, and performing an absolute value calculation for each complex signal to generate a first amplitude signal and a second amplitude signal;
Adding means for adding the first amplitude signal and the second amplitude signal;
An ultrasonic diagnostic apparatus comprising: The apparatus of claim 5.
An ultrasonic diagnostic apparatus comprising weighting means for weighting each amplitude signal or each complex signal before addition of the first amplitude signal and the second amplitude signal. The apparatus of claim 1.
Phase difference calculating means for calculating a phase difference between the first complex signal and the second complex signal;
Correction amount setting means for setting a phase correction amount based on the phase difference;
An ultrasonic diagnostic apparatus comprising:

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