[0027] Combine Figure 1 to Figure 9 The principle of the ultrasonic imaging system of the present invention is explained. Such as figure 1 The ultrasonic imaging system of the present invention shown has five main parts: a transducer 3, a transmission beam generator connected to it 1, a scanning motor controller connected to the transducer 3 and a transmission beam generator 1, and a transmission beam generator. The receiving beam processor 4 connected to the device 1 and the electronic computer 5 connected to the receiving beam processor 4. Among them, the transducer 3 is a high-frequency ultrasound (ultrasonic signal frequency is 15MHZ-80MHZ) transducer. Under the excitation of multiple high-voltage pulse signals (excitation signals) with different delays generated by the beam generator 1, the transducer 3 Generate ultrasound. Under the control of the scanning motor controller 2, the annular array transducer 3 can perform sector scanning, horizontal scanning and fixed scanning. The annular array transducer 3 converts the received return ultrasonic signal into an analog signal, that is, an analog echo signal, and sends it to the receiving beam processor 4 through the transmitting beam generator 1. The receiving beam processor 4 processes the analog echo signal and generates an ultrasound image. The electronic computer 5 is used for displaying and storing the ultrasound image data sent by the receiving beam processor 4.
[0028] figure 2 A cross-sectional schematic diagram of an annular array transducer with 8 annular array elements is given in. In the design, it can be designed as 5-ring, 6-ring, 7-ring or 8-ring array elements. Different array elements are connected to different signal channels, so the number of high-voltage excitation signal channels (forward signal channels) of the transmitting beam generator 1 and the number of echo signal acquisition channels (echo signal channels) of the receiving beam processor 4 Equal to the number of elements of the transducer. The operating frequency of the annular array transducer 3 is determined by the thickness of its piezoelectric material layer. The system supports the imaging of ultrasonic signals with a frequency of 15MHZ-80MHZ. It should be noted that this system can also support single-element transducers without changing the hardware.
[0029] The principle of ultrasonic transmission is image 3 Shown in. The transmitting beam generator 1 generates high-voltage pulse signals with different delays to excite different array elements to generate ultrasonic signals. The delay time can be calculated by the distance between the ultrasonic emission point of the different array elements and the target focus point and the ultrasonic velocity in the medium. The ratio is obtained. By controlling the delay time of the excitation signal time between different array elements, the system can accurately control the ultrasonic signals of different array elements to reach the target focus point at the same time. Therefore, the maximum signal excitation can be obtained and a stronger echo signal can be obtained.
[0030] Combine Figure 4 The process of receiving ultrasound in the present invention is explained. First set the target focus point, the receiving target processor 4 will accurately delay the echo signals of different elements according to the time difference between the target focus point and different elements, so that the echo signals of different elements can reach the addition at the same time The 4121 adder adds the echo signals of multiple array elements, so the energy of the multiple echo signals can be concentrated to obtain a larger echo signal amplitude. The rectangular frame between the annular array transducer 3 and the adder 4121 represents the delay length, and the echo signal delay of different echo channels is different. image 3 in image 3 The signal shown sends the focus point and Figure 4 The signal focus point shown is the same, and the focus point can be adjusted according to the actual situation.
[0031] The hardware block diagram of the transmit beam generator 1 is in Figure 5 Shown in. It includes a first FPGA 101 and multiple forward signal channels connected to it. Each forward signal channel includes a pulse driver 102, a pulse generator 103, and a transceiver switch 104. The first FPGA101 is used to control the delay and pulse width of the high-voltage pulse signal between different signal channels, which means that the system can support real-time dynamic focus imaging without the aid of other additional delay circuits. The pulse driver 102 provides a large pulse drive current to the pulse generator 103. The high-voltage pulse signal generated by the pulse generator 103 excites the annular array transducer 3 through the transceiver switch 104. The transceiver switch 104 coordinates the control of the forward signal channel and the echo signal channel of the transducer signal. The echo signal of the annular array transducer 3 will enter the receiving beam processor 4 through the transceiver switch 104, and will be in the receiving beam processor 4. In the process. In the present invention, the pulse generator 103 is a MOSFET (metal-oxide-semiconductor-field effect crystal). The forward signal channels of the transmitting beam generator 1 and the ring array transducer 3 have the same number of array elements, and they support a maximum of 8 channels and also support a single array element system. The transmitting beam generator 1 directly communicates with the receiving beam processor 4 and exchanges information.
[0032] The hardware design of the receiving beam processor 4 is as Image 6 Shown. The annular array transducer 3 sends the converted echo signal in the form of an analog signal to the amplifier 44 of the receiving beam processor 4 via the transceiver switch 104 of the transmitting beam generator 1. The amplifier 44 amplifies the amplitude of the echo signal. The filter 43 is an anti-aliasing filter, which mainly filters out signals exceeding the Nyquist frequency. The analog-to-digital converter 42 converts the amplified and filtered analog echo signal into a digital echo signal, and transmits it to the second FPGA 41 through the data interface 415. The second FPGA 41 completes real-time processing of multiple ultrasonic echo signals. The number of signal channels supported by the receiving beam processor 4 is matched with the number of array elements of the annular array transducer 3, and a maximum of 8 channels is supported, but a single-array element system is also supported.
[0033] Among the receiving beam processors 4, the second FPGA 41 is a programmable signal processor. The internal algorithm program can be customized according to different applications. In the present invention, the logical structure of the second FPGA 41 of the receiving beam processor 4 is as follows: Figure 7 Shown. The digital filter 411 filters out noise signals. The beam combiner 412 completes the accurate delay and synthesis of the signal. After beam synthesis, the ultrasonic echo signal is converted into a single-channel echo signal. The echo signal of the single channel is sent to the B-ultrasonic imaging module 413 or the Doppler imaging module 414 for imaging processing.
[0034] The echo signal processed by the beam combiner can be used for B-mode imaging or Doppler imaging. When the system is applied to B-ultrasound imaging, the envelope extraction module extracts the envelope information of the echo signal for grayscale imaging. The coordinate conversion module is a user-selectable module. If the motion mode of the circular array transducer 3 is horizontal linear scanning, the coordinate conversion module can be removed; if the motion mode of the circular array transducer 3 is sector scanning, coordinate conversion is required Module to complete the coordinate conversion of the ultrasound image (polar coordinate to Cartesian coordinate). The data compression module compresses the ultrasonic echo signal according to the amount of ultrasonic data. The processed image data will be transmitted to the electronic computer 5 through the data interface 415 for subsequent imaging processing. When the system is applied to Doppler imaging, the integral demodulation module is used to convert the single-ended echo signal into a differential echo signal. The spectrum extraction module extracts the frequency information of the echo signal for Doppler imaging display. After data compression, it can be transmitted to the computer 5 for display processing.
[0035] In the second FPGA 412 of the receiving beam processor 41, the specific implementation of the beam combiner 412 is as follows: Figure 8 Shown. In order to ensure accurate delay, the delay of each channel is divided into two parts: integer delay 4122 and fractional delay 4123. The integer delay 4122 roughly delays the echo signal. The fractional delayer 4123 will complete the precision delayed echo signal. Then the signals are synthesized by the multiple adder 4121, and finally sent to the next-stage image processors 413 and 414 for processing. Through integer delay and fractional delay, the echo signal reaches the adder at the same time more accurately, thereby obtaining a finer image. The type of the data interface 415 between the receiving beam processor 41 and the electronic computer 5 in this system is USB, PCI or PCI-Express.
[0036] Such as Picture 9 As shown, the ultrasound imaging system supports multiple dynamic focus area imaging at the same time, and smooth filtering processing is adopted between the focus areas, and the above processing is implemented by FPGA.
[0037] In a word, the annular array transducer of the present invention overcomes the problem that the visible area of a single-array element system is too narrow and the lateral resolution is not balanced. At the same time, compared with the linear array high-frequency ultrasonic imaging system, the cost is low and the cost performance is higher. . The present invention uses a ring-shaped array transducer to excite and collect high-frequency ultrasonic signals. The number of array elements is much smaller than that of a linear array transducer, but the performance is comparable. The transmitting beam generator generates multiple high-voltage pulse signals with adjustable timing to excite the transducer to perform dynamic focusing, so that the ultrasonic signal reaches the target focus point at the same time, and a stronger echo signal is obtained. Each array element has a corresponding forward signal and echo signal channel, which reduces signal interference and can obtain more accurate images.
[0038] The above are only the preferred embodiments of the present invention. It should be pointed out that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and substitutions can be made, and these improvements and substitutions should also be considered This is the protection scope of the present invention.
