RU2631049C2 - Device for multipath reception of ultrasonic signals - Google Patents

Abstract

FIELD: medicine.

SUBSTANCE: invention refers to medical equipment. The multipath ultrasonic signal receiver contains a probing beam shaper, a sensor receiving line conditioners, multipliers, delay lines, adders. After formation of four reception beams R_i,j j = 1, 2, 3, 4 on the i-th probing using ray generators 3, 4, 5, 6, reception beams R_i,1 and R_i,2 are multiplied by means of 7 and 8 multipliers, respectively, by W₂ and W₁ weighting factors and are fed to adder 13 and adder 14, respectively. The second inputs of adder 13 and adder 14 receive the data of reception beams R_i-1,3 and R_i-1,4 formed on the previous i-1-th probing and multiplied by W₂ and W₁ factors, respectively. As a result, two first line images L_3i-4 and L_3i-3 are formed at the outputs of adder 13 and adder 14. Then, the data of the third reception beam R_i,3 and the fourth reception beam R_i,4 are delivered from multiplier 9 and multiplier 10, respectively, to delay line 11 and delay line 12, carrying the signal delay by a probing tact and will be used for formation of image lines based on the results of i+1-th sensing, and delay lines 11, 12 represent a standard FIFO-type memory. The third line of the image is formed by addition by means of adder 15 of the second and the third reception beams R_i,2, R_i,3, delivered from receiving lines driver 4 output and receiving lines driver 5 output, respectively.

EFFECT: application of this invention provides a high frame rate when imaging the moving cardiac structures with geometric distortion compensation.

4 cl

Description

The invention relates to the field of medical instrumentation, in particular to devices for ultrasonic echolocation of internal organs, and can be used in medical diagnostic systems.

From the current level of technology, it is known an ultrasonic chart-forming device (DFU) for multipath reception of ultrasonic signals, performing the simultaneous formation of L rays, which includes N receiving signal channels, which receive echo signals from N sensor elements, each receiving signal channel is electrically connected via an individual analog-to-digital converter (ADC) with primary random access memory type FIFO (First Input First Output), the output of which is connected to a filter-interpolator, the output of which It is connected to L FIFO type memory modules, where L is the number of receiving beams simultaneously formed, the output of each FIFO type memory module is connected to the first input of the channel adder, the second input of which receives a signal from a neighboring channel (see, for example, United States Patent 6,695,783, published February 24, 2004). The multipath device provides the necessary frame rate of the ultrasound image for large probing depths due to the simultaneous formation of several receiving rays after each radiation. Increasing the frame rate of ultrasound images is especially important when examining moving tissues of heart structures at a great depth of location.

The disadvantage of this technical solution is the presence of artifacts in the generated ultrasound image due to geometric distortions arising from the mismatch of the probe beam with the receiving rays.

The spatial displacement of the probe beam generated by ultrasound in the tissue and the receiving rays relative to each other leads to the bending and bias of the total beam profile to the receiving radiation (Tore Gruner Bjastad High frame rate ultrasound using parallel beamforming, Thesis for degree of Philosophy Doctor, Trondheim , 2009). In this case, the bending of the beam is manifested in the fact that the total beam for radiation-reception is not a straight line, but partially repeats the shape of the probe beam. The skew of the beam is manifested in the asymmetry of the beam profile and the different level of the side lobes located at the same distance from the main lobe of the radiation-reception pattern.

In addition to the deterioration of the quality of the grayscale image, geometric distortions that occur during multipath reception lead to a bias in the assessment of the Doppler blood flow velocity (see, for example, United States Patent 8,475,380, published July 2, 2013).

Also known in the art is the Synthetic Transmit Beams (STB) method (see Tor. Hergum, Tore. Bjastad, Kjell. Kristoffersen, "Parallerl Beamfroming Using Synthetic Transmit Beams", IEEE Trans. Ultrason. Ferroelectr. Freq. Control. Freq. Control. , vol. 54, no. 2, pp. 271-279, 2007), which can significantly reduce the level of artifacts arising from multipath reception, and it is also known a device that can implement this method (see, for example, United States Patent 8,137,172, published on March 20, 2012), comprising receiving beam shapers, delay line multipliers, and an adder.

A device that implements the method of synthesized sounding rays performs multi-beam reception with overlapping rays from successive soundings in such a way that half of the rays of the new sounding have the same directions as the rays of the previous sounding. To reduce the level of artifacts in the process of multipath reception, a weighted coherent summation of RF (Radio Frequency) signals of the receiving lines of the same direction from sequential soundings is performed. In FIG. Figure 1 shows the algorithm of the STB method in the case of simultaneous reception of 4 lines using the following notation:

T _i is the emitting beam of the i-th sounding, i = 1, 2, ..., N, N is the number of soundings used to form one image frame;

R _{i, j} is the j-th receiving beam of the i-th sounding, j = 1, 2, 3, 4;

L _k is the line of the formed image, k = 1, 2, ..., 2N-2.

Before summing the receiving rays of adjacent soundings, the weighing of the receiving rays of each sounding is performed using the values: 0.25, 0.75, 0.75, 0.25.

The compensation of geometric distortions resulting from multipath reception by the method of synthesized probe beams is illustrated in FIG. 2. As can be seen from FIG. 2, the greatest geometric distortions occur in the area of the focus on radiation, and the elimination of these distortions is reduced to the summation of the receiving lines from neighboring soundings of the same spatial direction, multiplied by the weighting coefficients [W ₁ , W ₂ ].

Although after each sounding four reception lines are simultaneously formed, but due to the overlapping of the receiving rays of adjacent soundings, only two image lines are formed. Accordingly, in comparison with the standard single-beam reception, the frame rate of the image does not increase four times, but only twice.

The task to which the claimed technical solution is directed is to increase the frame rate of the generated image with the compensation of geometric distortions in the multipath mode.

This problem is solved due to the fact that after the formation of the i-th probe four receiving rays R _{i, j} , j = 1, 2, 3, 4 using beam shapers 3, 4, 5, 6, the receiving rays R _{i, 1} and R _{i, 2} are multiplied using the multipliers 7 and 8, respectively, by the values of the weighting factors W ₂ and W ₁ , and are supplied respectively to the adder 13 and adder 14. The second inputs of the adder 13 and adder 14 are fed multiplied by the coefficients W ₂ and W _1, respectively data of the receiving rays R _i-1,3 and R _i-1,4 generated on the previous i-1-m sounding. As a result, at the outputs of the adder 13 and the adder 14, the first two image lines L _3i-4 and L _{3i-3 are formed} .

The data of the third receiving beam R _{i, 3} and the fourth receiving beam R _{i, 4} from the outputs of the multiplier 9 and the multiplier 10 are respectively supplied to the delay line 11 and the delay line 12, which delay the signal per sensing clock, and will be used when generating image lines according to the results i + 1st sounding. Delay lines 11, 12 are standard FIFO type memory.

The third line of images is formed by adding, using the adder 15, the second beam and the third receiving rays R _{i, 2} , R _{i, 3} , respectively, coming from the output of the shaper of the receiving lines 4 and from the output of the shaper of the receiving lines 5.

The technical result provided by the given set of features is to ensure a high frame rate when forming an image of moving structures of the heart with compensation for geometric distortions.

The essence of the claimed device is illustrated by drawings that do not cover and, moreover, do not limit the scope of claims for this decision, but are only illustrative materials of a particular case of the device. The drawings show:

in FIG. 1 is a block diagram of an STB algorithm;

in Fig.2 - compensation for geometric distortion by the STB method;

in FIG. 3 is a block diagram of a device;

in FIG. 4 is a block diagram of a modified STB algorithm;

The device includes a shaper 1 of the probe beam, sensor 2, shapers of the receiving lines 3-6, multipliers 7-10, delay lines 11, 12, adders 13-15.

The device operates as follows. The probe beam shaper 1 generates the excitation signals of the piezoelectric elements of the sensor 2 delayed between themselves in accordance with the established focus on the radiation. Ultrasonic echo signals reflected from inhomogeneities of the tissues are converted by the elements of the sensor 2 into electrical signals and fed to the shapers of the receiving lines 3-6. Shapers of receiving lines 3-6 provide the reception of ultrasonic signals based on the dynamic adjustment of the system of signal delays to obtain maximum lateral resolution over the entire depth of sounding. The formation of the receiving lines with different spatial directions is realized through the use of different sets of signal delays in the shapers of the receiving lines 3-6. In this case, the shapers of the receiving lines 3-6 can be built according to any of the known schemes (see, for example, patent for utility model 142201 dated 05/20/2014).

The device implements a modified STB method allowing to provide a higher frame rate of the ultrasound image than the standard STB method described above (see Fig. 1). In FIG. 4 shows the algorithm of the modified STB method while receiving 4 lines. It is the mode of simultaneous reception of 4 lines that is most widely used in high-class ultrasound echocardiographs (see, e.g., Tore Gruner Bjastad High frame rate ultrasound using parallel beamforming, Thesis for degree of Philosophy Doctor, Trondheim, 2009). Unlike the standard STB method, the modified STB method provides in the mode of receiving 4 lines the simultaneous formation of not two, but three lines of images.

In accordance with the algorithm of FIG. 4, after each i-th sounding (i = 1, 2, ...) three image lines L _3i-4 , L _3i-3 , L _3i-2 are formed simultaneously from four receiving rays R _{i, j} , j = 1, 2 , 3, 4, using the formulas:

L _3i-4 = W ₂ ⋅R _i-1,3 + W ₁ ⋅R _{i, 1} )

L _3i-3 = W ₁ ⋅R _i-1,4 + W ₂ ⋅R _{i, 2} )

L _3i-2 = 0.5⋅ (R _{i, 2} + R _{i, 3} )

After the formation of the four receiving beams R _{i, j} , j = 1, 2, 3, 4 on the ith probe using the beam shapers 3, 4, 5, 6, the receiving beams R _{i, 1} and R _{i, 2} are multiplied using multipliers 7 and 8, respectively, to the values of the weighting coefficients W ₂ and W ₁ and are supplied respectively to the adder 13 and the adder 14. The data of the receiving rays R _i-1,3, respectively multiplied by the coefficients W ₂ and W _1, are supplied to the second inputs of the adder 13 and adder 14 and R _i-1,4 formed on the previous i-1th probe. As a result, at the outputs of the adder 13 and the adder 14, the first two image lines L _3i-4 and L _{3i-3 are formed} .

The data of the third receiving beam R _{i, 3} and the fourth receiving beam R _{i, 4} from the outputs of the multiplier 9 and the multiplier 10 are respectively supplied to the delay line 11 and the delay line 12, which delay the signal per sensing clock, and will be used when generating image lines according to the results i + 1st sounding. Delay lines 11, 12 are standard FIFO type memory.

The third line of images is formed by adding, using the adder 15, the second beam and the third receiving rays R _{i, 2} , R _{i, 3} , respectively, coming from the output of the shaper of the receiving lines 4 and from the output of the shaper of the receiving lines 5.

The use of ultrasound signals multipath reception devices in medical diagnostic systems will make it possible to create ultrasound devices for visualizing the state of internal organs of a person, performing diagnostic studies with obtaining images of high diagnostic quality due to the result achieved in this technical solution, which consists in increasing the frame rate of the generated image while maintaining low geometric distortion.

Claims (1)

A multipath device for receiving ultrasonic signals, comprising a probe beam shaper, a sensor, receiving line shapers, multipliers, delay lines, adders, characterized in that after the formation of four receiving beams at the i-th probe R _{i, j} j = 1, 2, 3, 4 using beam shapers 3, 4, 5, 6, the receiving rays R _{i, 1} and R _{i, 2} are multiplied with the help of multipliers 7 and 8, respectively, by the values of the weight coefficients W ₂ and W ₁ and are transmitted respectively to the adder 13 and adder 14, multiplied to the second inputs of the adder 13 and adder 14 are multiplied respectively by the coefficients W _1, W ₂ and data reception beam R _i-1,3, and R _i-1,4, formed on the previous i-1-th sensing, as a result of the outputs of adder 13 and adder 14 are formed by the first two image lines L _3i-4 and L _3i-3 , then the data of the third receiving beam R _{i, 3} and the fourth receiving beam R _{i, 4} from the outputs of the multiplier 9 and the multiplier 10 are respectively supplied to the delay line 11 and the delay line 12, which delay the signal per probe clock , and will be used in the formation of image lines based on the results of the i + 1-st sounding, and delay lines 11, 12 are standard FIFO memory, and the third image line is formed by adding, with the help of adder 15, the second beam and the third receiving rays R _{i, 2} , R _{i, 3} , respectively, coming from the output of the shaper of the receiving lines 4 and c output shaper receiving lines 5.

Images