CN112650707A - Multichannel photoacoustic signal delay device, multichannel photoacoustic signal delay system, signal processing method, terminal and medium - Google Patents
Multichannel photoacoustic signal delay device, multichannel photoacoustic signal delay system, signal processing method, terminal and medium Download PDFInfo
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Abstract
The application provides a multichannel photoacoustic signal delay device, system, signal processing method, terminal, medium, comprising: the delay units are used for accessing the input signals and outputting the input signals after delay processing; at least one adder for adding the signals; and after the delay processing is carried out on part or all of the multi-path input signals by the delay unit and the addition processing is carried out by the adder, the signals are output as one path of output signals. The all-in-one data acquisition system can combine PA signals detected by 4 paths (or more paths) of ultrasonic probes into one path to be output to a data acquisition card for acquisition. Therefore, the requirements of the PAT system on the number of DAQ channels can be reduced, the system cost is reduced, and the PAT system with the fixed number of DAQ channels can realize the reduction of the scanning time during the PAT data acquisition and improve the imaging speed.
Description
Technical Field
The present application relates to the field of signal processing technologies, and in particular, to a multi-channel photoacoustic signal delay apparatus, a multi-channel photoacoustic signal delay system, a multi-channel photoacoustic signal delay method, a multi-channel photoacoustic signal delay terminal, and a multi-channel photoacoustic signal delay medium.
Background
PAT imaging refers to Photoacoustic tomography (Photoacoustic tomography), which is a novel nondestructive noninvasive biomedical imaging technology, can well combine the respective advantages of optical imaging technology and ultrasonic imaging technology, and can realize high-resolution and high-contrast functional imaging of tissue with larger depth.
In the PAT imaging system, an ultrasonic array probe detects photoacoustic signals at a plurality of angles, and the signal of each channel is correspondingly connected to a collecting port of a DAQ (digital acquisition card), so that when a plurality of paths of photoacoustic signals are captured simultaneously, a plurality of channels of DAQ collecting ports are correspondingly needed. Typically, the irradiation frequency of the laser is very low (less than 20Hz) in PAT systems, which results in more idle operation of the DAQ at the cost of a significant portion of PAT systems.
Content of application
In view of the above-mentioned drawbacks of the prior art, an object of the present application is to provide a multi-channel photoacoustic signal delay apparatus, system, signal processing method, terminal, and medium for solving the problem of high cost and low efficiency of PAT imaging in the prior art.
To achieve the above and other related objects, a first aspect of the present application provides a multi-channel photoacoustic signal delay apparatus accessing multiple input signals, comprising: the delay units are used for accessing the input signals and outputting the input signals after delay processing; at least one adder for adding the signals; and after the delay processing is carried out on part or all of the multi-path input signals by the delay unit and the addition processing is carried out by the adder, the signals are output as one path of output signals.
In some embodiments of the first aspect of the present application, the apparatus comprises: a plurality of delay cells connected in series; each delay unit is connected with one input signal, and the next delay unit in the series connection is also connected with the delay signal output by the previous delay unit through an adder; under the condition that all signals are subjected to delay processing by the delay units, the output signal of the last delay unit in the series connection is output through one output signal of the delay device; and under the condition that partial signals are subjected to delay processing by the delay units, adding an output signal of the last delay unit in the series connection and an input signal which is not subjected to delay processing by the delay units by the adder to serve as an output signal to be output.
In some embodiments of the first aspect of the present application, the apparatus comprises: a plurality of delay cells connected in parallel; each delay unit is connected with one input signal; under the condition that all signals are subjected to delay processing by the delay units, output signals of all delay units connected in parallel are added by an adder and then are output as one path of output signal; under the condition that partial signals are delayed by the delay units, the output signals of the delay units connected in parallel and the input signals which are not delayed by the delay units are added by the adder to be output as one output signal.
In some embodiments of the first aspect of the present application, the delay time of each delay unit is positively correlated to its acoustic wave propagation medium length and negatively correlated to the speed of the acoustic wave in the propagation medium.
To achieve the above and other related objects, a second aspect of the present application provides a delay cell structure including: the ultrasonic transmitting unit is used for receiving an input signal and generating corresponding ultrasonic waves; an ultrasonic propagation medium for propagating the ultrasonic wave; an ultrasound receiving unit for receiving the ultrasound waves propagated by the ultrasound propagation medium.
To achieve the above and other related objects, a third aspect of the present application provides a photoacoustic imaging system based on delay of a multi-channel photoacoustic signal, comprising: the pulse laser generating module is used for generating laser pulses and irradiating the laser pulses to the surface of the sample; a plurality of ultrasonic probes for performing ultrasonic testing on the sample; the ultrasonic probe is arranged on the rotary displacement table and rotates along with the rotary displacement table; the driving motor is in driving connection with the rotary displacement table so as to adjust the receiving angle of the ultrasonic probe for receiving the laser pulse; the multi-channel amplification module is used for receiving and amplifying ultrasonic signals from the plurality of ultrasonic probes; the multi-channel delay module is connected with the multi-channel amplification module and outputs a path of combined signal after delay processing is carried out on the amplified multi-channel signal; the data acquisition module is connected with the multichannel delay module to acquire the output combined signal; and the data calculation module is connected with the data acquisition module to receive and recover the combined signal to the multiple independent signals for imaging processing.
To achieve the above and other related objects, a fourth aspect of the present application provides a signal processing method based on delay of a multi-channel photoacoustic signal, comprising: acquiring an output signal of the multichannel photoacoustic signal delay device; and restoring the output signals into multi-channel signals with the same number as the input signals in the digital domain according to the corresponding delay time for imaging processing.
To achieve the above and other related objects, a fifth aspect of the present application provides a computer-readable storage medium having stored thereon a computer program which, when executed by a processor, implements the method for signal processing based on delay of a multichannel photoacoustic signal.
To achieve the above and other related objects, a sixth aspect of the present application provides an electronic terminal comprising: a processor and a memory; the memory is used for storing a computer program, and the processor is used for executing the computer program stored by the memory so as to enable the terminal to execute the signal processing method based on the multichannel photoacoustic signal delay.
As described above, the multi-channel photoacoustic signal delay apparatus, system, signal processing method, terminal, and medium of the present application have the following advantageous effects: the all-in-one data acquisition system provided by the invention can combine PA signals detected by 4 paths (or more paths) of ultrasonic probes into one path to be output to a data acquisition card for acquisition. Therefore, the requirements of the PAT system on the number of the DAQ channels can be met, the system cost is reduced, the PAT system with the fixed number of the DAQ channels can achieve the purposes of reducing the scanning time during the PAT data acquisition and improving the imaging speed.
Drawings
Fig. 1A is a schematic diagram of a multi-channel photoacoustic signal delay apparatus according to an embodiment of the present application.
Fig. 1B is a schematic diagram of a multi-channel photoacoustic signal delay apparatus according to an embodiment of the present application.
Fig. 2 is a schematic diagram of a delay cell structure according to an embodiment of the present application.
Fig. 3A is a schematic diagram illustrating input signals of a delay unit according to an embodiment of the present application.
Fig. 3B is a schematic diagram illustrating output signals of a delay unit according to an embodiment of the present application.
Fig. 4A is a schematic diagram illustrating a set of four-in-one combined signal waveforms according to an embodiment of the present application.
Fig. 4B is a waveform diagram of signal 1 in the combined signal after signal recovery according to an embodiment of the present application.
Fig. 4C is a waveform diagram of signal 2 in the combined signal after signal recovery according to an embodiment of the present application.
Fig. 4D is a waveform diagram of signal 3 in the combined signal after signal recovery according to an embodiment of the present application.
Fig. 4E is a waveform diagram of signal 4 in the combined signal after signal recovery according to an embodiment of the present application.
Fig. 5 is a schematic structural diagram of a photoacoustic imaging system based on multi-channel photoacoustic signal delay in an embodiment of the present application.
Fig. 6 is a schematic flow chart illustrating a signal processing method based on multi-channel photoacoustic signal delay according to an embodiment of the present application.
Fig. 7A is a schematic diagram illustrating an image reconstructed by a conventional detection method according to an embodiment of the present application.
Fig. 7B is a schematic diagram of a reconstructed image based on a delay line sampling method according to an embodiment of the present application.
Fig. 8 is a schematic structural diagram of an electronic terminal according to an embodiment of the present application.
Detailed Description
The following description of the embodiments of the present application is provided by way of specific examples, and other advantages and effects of the present application will be readily apparent to those skilled in the art from the disclosure herein. The present application is capable of other and different embodiments and its several details are capable of modifications and/or changes in various respects, all without departing from the spirit of the present application. It is to be noted that the features in the following embodiments and examples may be combined with each other without conflict.
It is noted that in the following description, reference is made to the accompanying drawings which illustrate several embodiments of the present application. It should be understood that the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context indicates otherwise. It will be further understood that the terms "comprises," "comprising," and/or "comprising," when used in this specification, specify the presence of stated features, operations, elements, components, items, species, and/or groups, but do not preclude the presence, or addition of one or more other features, operations, elements, components, items, species, and/or groups thereof. The terms "or" and/or "as used herein are to be construed as inclusive or meaning any one or any combination. Thus, "A, B or C" or "A, B and/or C" means "any of the following: a; b; c; a and B; a and C; b and C; A. b and C ". An exception to this definition will occur only when a combination of elements, functions or operations are inherently mutually exclusive in some way.
Analog signal delay lines are useful in many applications, widely used in radar, electronic computers, color television systems, communication systems, and measurement instruments (e.g., oscilloscopes), but few design methods have been mentioned regarding delay circuits.
To achieve a delay in a digital signal, the signal is typically input into one end of a shift register and appears at the other end after N clock cycles, where N is the length of the register. But analog delays are more difficult to implement, the achievable method depends on the length of the required delay, for long delays, which may be only a few seconds, the only practical method being recording and copying. Tape cycling is an example and some early computers used rotating drum storage based on this principle. In electrical signals, an analog delay line is a network of cascaded electronic elements, each element producing a time or phase difference between its input and output signals. Other types of delay lines also include acoustic (typically ultrasonic), magnetostrictive, and surface acoustic wave devices, among others.
The general method of creating the delay is to use the propagation time of the wave, i.e. the time delay that S/V will be created when a wave propagating at a speed V is received at a distance S. For ideal wave propagation, the propagation velocity V is independent of frequency, and the velocities are the same in the same medium. Electromagnetic waves may be transmitted at one end of a transmission line of length L and received at the other end with a delay time of S/V,
The wave speed for a non-dispersive propagation transmission line is constant. And the propagation speed of the electric signal is 3x 10 of the speed of light8m/s, the delay line of the electrical signal is only suitable for delays measured in nanoseconds, due to the limitation of the length of the transmission line, the upper limit of which may be less than one microsecond. In addition, the ultrasonic delay line is suitable for some occasions needing long time delay and high stability. Because the propagation speed of ultrasonic waves in liquid is about 1480m/s and the attenuation is much slower than the propagation speed of radio waves in conductors, a longer delay time can be obtained by converting electrical signals into mechanical vibrations through a propagation medium based on this principle.
In medical imaging technology, a large number of analog signals need to be received, such as ultrasonic imaging and photoacoustic tomography (PAT), and most of the signals are transient pulses, so that a large number of DAQ (data acquisition) acquisition ports are consumed for signal acquisition, which leads to a sharp increase in the cost of the whole system.
In view of this, the present invention provides an all-in-one data acquisition system for PAT, so as to effectively improve the utilization efficiency of the data acquisition card of the PAT system. Specifically, in the PAT imaging system, a photoacoustic signal (PA signal) is a spherical wave generated by pulsed laser irradiation, while the signal is synchronously detected by ultrasonic probes of different reception angles. The all-in-one data acquisition system provided by the invention can combine PA signals detected by 4 paths (or more paths) of ultrasonic probes into one path to be output to a data acquisition card for acquisition. Therefore, the requirements of the PAT system on the number of the DAQ channels can be met, the system cost is reduced, the PAT system with the fixed number of the DAQ channels can achieve the purposes of reducing the scanning time during the PAT data acquisition and improving the imaging speed. Hereinafter, the technical solution of the present invention will be explained in detail with reference to a plurality of embodiments.
Example one
As shown in fig. 1A and 1B, schematic diagrams of a multi-channel photoacoustic signal delay apparatus in an embodiment of the present invention are shown. The multichannel photoacoustic signal delay device of the present embodiment accesses a plurality of input signals, and includes: the delay units are used for accessing the input signals, delaying the input signals and outputting the delayed input signals; at least one adder for adding the signals; and after the delay processing is carried out on part or all of the multi-path input signals by the delay unit and the addition processing is carried out by the adder, the signals are output as one path of output signals.
For the convenience of understanding, the following description will take a four-in-one photoacoustic signal delay apparatus as an example, that is, a four-input single-output analog signal delay line module is used to collect more photoacoustic signals from fewer DAQ channels, and then the four-in-one combined signal is restored to a four-path signal for PAT imaging, and the structure of the delay unit in fig. 1A and 1B is described as follows.
FIG. 1A shows a schematic diagram of a serial structure of delay units, wherein the delay module comprises three delay units (delay unit one, delay unit two, and delay unit three) and three analog adders. The input signal achieves different delays after passing through different numbers of delay units, for example: the input signal 1 realizes the time delay of 3 unit time lengths after passing through 3 delay units, the input signal 3 realizes the time delay of 1 unit time length after passing through 1 delay unit, and the signal 4 does not have time delay after passing through any delay unit. The unit duration of the delay depends on the structure of the delay cell, and the specific structure of the delay cell will be shown in fig. 2.
It should be noted that fig. 1A shows a case where a part of signals are delayed by the delay units, that is, the input signal 1, the input signal 2, and the input signal 3 are delayed by the delay units one, two, and three, respectively, but the input signal 4 is not delayed by any delay unit. And when all the signals are delayed by the delay units, the output signal of the last delay unit in the series connection is output through one output signal of the delay device.
Fig. 1B shows a schematic diagram of a parallel structure of delay units, in which the delay durations of three delay units (delay unit one, delay unit two, and delay unit three) are different, for example: the input signal 1 achieves a delay of x1 unit duration after passing through the first delay unit, the input signal 2 achieves a delay of x2 unit duration after passing through the second delay unit, the input signal 3 achieves a delay of x3 unit duration after passing through the third delay unit, and the input signal 4 does not have a delay because it does not pass through any delay unit. The magnitude relationship among x1, x2, and x3 is x1 < x2 < x3, and the position of the output waveform in fig. 1B can be known. Therefore, according to the parallel structure of the delay units, the idea that even more signal inputs are combined into one signal output can be realized.
It should be noted that fig. 1B shows a case where a part of the signals are delayed by the delay units, that is, the input signal 1, the input signal 2, and the input signal 3 are delayed by the delay units one, two, and three, respectively, but the input signal 4 is not delayed by any delay unit. However, when all the signals are delayed by the delay units, the output signals of the delay units connected in parallel are added by an adder and then output as one output signal.
In the schematic structural diagram of the delay unit shown in fig. 2, the delay unit of the present embodiment adopts an acoustic delay structure, and since the PA signal frequency is high, the delay unit is an ultrasonic signal delay structure, and includes an ultrasonic transmitting unit 21, an ultrasonic propagation medium (acoustic conductor) 22, and an ultrasonic receiving unit 23.
For example, the present embodiment employs a ceramic piezoelectric sheet or an ultrasonic probe as an ultrasonic transmitting and receiving unit, and water as an acoustic propagation medium. The working principle is as follows: after the ultrasonic transmitting unit receives the input signal, the ultrasonic transmitting unit generates ultrasonic waves according to the input signal and transmits the ultrasonic waves to the ultrasonic receiving unit on the other side for receiving through water, and the time difference between the output end signal and the input end signal meets the following formula 1):
where t denotes a delay time, L denotes an acoustic propagation medium length, and v denotes a velocity of an acoustic wave in the propagation medium. Therefore, the delay time of the delay unit structure is positively correlated with the length of the ultrasonic propagation medium and negatively correlated with the propagation speed of the ultrasonic wave in the ultrasonic propagation medium.
In the case of a single delay structure, which can be shifted in time domain with respect to an input signal, the transmission characteristics of a single delay unit are shown in fig. 3A and 3B, wherein fig. 3A represents the input signal of the delay unit, fig. 3B represents the output signal of the delay unit, the output signal varies with the variation of the input signal, and the input and output thereof satisfy the following formula 2):
(T) ═ T × g (T-dt); formula 2)
Wherein f (T) represents an output signal, g (T) represents an input signal, dt represents a delay time, and T is a transmission matrix of the acoustic delay line. The delay time of the delay unit depends on the acoustic propagation medium length, i.e. the acoustic propagation path length from the ultrasound transmitting unit to the ultrasound receiving unit.
The data acquisition card acquires an all-in-one (such as four-in-one) combined signal, and the waveform of the combined signal is composed of a plurality of parts and is a signal obtained by translating the waveform of each path of signal in the time domain. As shown in fig. 4A, a set of four-in-one combined signal waveforms, which are combined by four sets of signals after being delayed for different durations, can be restored to 4 paths of signals in a digital domain according to corresponding delay times after the data are acquired, and are four paths of PA signals after being delayed and restored respectively as shown in fig. 4B to 4E. The delayed signal recovery satisfies the following equation 3) and equation 4):
g1[n]＝f[n+dN]；(0＜n＜N1) (ii) a Formula 3)
gi[n]＝Ti -1×f[n+dNi]；(Ni-1＜n＜Ni) (ii) a Formula 4)
It should be noted that the above formulas are all discrete digital signals, where g1[n]Representing a first part of the combined signal, which is the signal without the delay structure, for a total of N1A piece of data; gi[n]Indicating the i-th delayed signal, dN, of the combined signaliThe number of data points corresponding to the delay time in the digital domain; t isi -1The inverse matrix of the ith delay structure transmission matrix is shown; wherein, dNiCan be calculated from equation 5):
dNi＝fs×ti(ii) a Equation 5)
Wherein f issRepresenting the DAQ sampling rate, tiCan be calculated by equation 1).
Therefore, the multi-in-one data acquisition system based on the acoustic delay can realize that a single DAQ acquisition port acquires multi-path signals and restores the multi-path signals into the multi-path signals in a digital domain, and the PAT system based on the method can reduce the system cost and accelerate the imaging speed.
Example two
As shown in fig. 5, a schematic structural diagram of a photoacoustic imaging system based on multi-channel photoacoustic signal delay in an embodiment of the present invention is shown. The embodiment provides a photoacoustic imaging system based on an all-in-one delay line signal acquisition structure, which comprises: a high power pulse laser 51 (wavelength 532 nm), a stepping motor 52, a rotary displacement table 54 with adjustable stepping angle for controlling different receiving angles of a probe 53, a multi-channel amplifier and multi-channel delay line module 55, a data acquisition module 56, a signal generator 57 and a computer device 59.
The signal generator 57 is connected to the high power pulse laser 51 for supplying various frequency, waveform and output level electric signals, etc. to the high power pulse laser 51. The pulse laser emitted by the high-power pulse laser 51 is adjusted through the optical fiber 58 and the optical path to enable the laser to be uniformly irradiated on the surface of the sample in parallel, wherein the convex lens 541 adjusts the laser to enable the laser to be output in parallel, and the ground glass 542 is used for homogenizing the laser energy; the stepping motor 52 controls the receiving angle of the probe 53; the photoacoustic signal received by the ultrasonic probe 53 is amplified by the multi-channel amplifier and then transmitted to the all-in-one delay module, the delay line module combines 4 input signals into 1 path of output and is collected by the data acquisition card 55, and the combined signal output by the delay line is restored into 4 paths of signals by the computer 57 and then can be used for imaging.
It should be noted that, in the conventional data acquisition method, each probe receives a signal and is connected with a data acquisition channel, and the all-in-one data acquisition system provided by the patent can meet the system requirements and complete photoacoustic imaging by only using one fourth or less data acquisition channels of the conventional sampling method. The acoustic delay-based all-in-one data acquisition system not only is suitable for a PAT imaging system, but also is suitable for other types of systems requiring a large amount of signal acquisition, such as ultrasonic imaging.
EXAMPLE III
As shown in fig. 6, a flow chart of a signal processing method based on multi-channel photoacoustic signal delay in an embodiment of the present invention is shown. The signal processing method of the present embodiment includes steps S61 and S62.
It should be noted that the signal processing method of the present embodiment can be applied to various types of hardware devices. Such as controllers including, but not limited to, ARM (advanced RISC machines) controllers, FPGA (field Programmable Gate array) controllers, SoC (System on chip) controllers, DSP (digital Signal processing) controllers, or MCU (micro controller Unit) controllers, among others. The hardware devices may also be, for example, a computer that includes components such as memory, a memory controller, one or more processing units (CPUs), a peripheral interface, RF circuitry, audio circuitry, speakers, a microphone, an input/output (I/O) subsystem, a display screen, other output or control devices, and external ports; the computer includes, but is not limited to, Personal computers such as desktop computers, notebook computers, tablet computers, smart phones, smart televisions, Personal Digital Assistants (PDAs), and the like. In other embodiments, the hardware device may also be a server, where the server may be arranged on one or more entity servers according to various factors such as functions and loads, or may be formed by a distributed or centralized server cluster, and this embodiment is not limited in this embodiment.
In step S61, an output signal of the multi-channel photoacoustic signal delaying means is acquired. The working principle of the multi-channel photoacoustic signal delay apparatus is described in detail above, and is not described herein again.
In step S62, the output signals are restored in the digital domain into a plurality of signals in accordance with the number of input signals by corresponding delay times for imaging processing.
Specifically, the delayed signal recovery satisfies the following equation:
g1[n]＝f[n+dN]；(0＜n＜N1)；
gi[n]＝Ti -1×f[n+dNi]；(Ni-1＜n＜Ni)；
it should be noted that the above formulas are all discrete digital signals, where g1[n]Representing a first part of the combined signal, which is the signal without the delay structure, for a total of N1A piece of data; gi[n]Indicating the i-th delayed signal, dN, of the combined signaliThe number of data points corresponding to the delay time in the digital domain; t isi -1The inverse matrix of the ith delay structure transmission matrix is shown; wherein, dNiCan be calculated by the following formula:
dNi＝fs×ti；
wherein f issRepresenting the DAQ sampling rate, tiCan be calculated from equation 1) above.
Therefore, the multi-in-one data acquisition system based on the acoustic delay can realize that a single DAQ acquisition port acquires multi-path signals and restores the multi-path signals into the multi-path signals in a digital domain, and the PAT system based on the method can reduce the system cost and accelerate the imaging speed.
Example four
In this embodiment, in order to verify the feasibility of the present invention, the sample was imaged by PAT system, and the conventional photoacoustic signal detection and the photoacoustic signal detection based on acoustic delay line recovery were compared. The structure of the multi-channel photoacoustic signal delay apparatus, the structure of the photoacoustic imaging system based on the multi-channel photoacoustic signal delay, and the principles thereof have been explained in the above embodiments, respectively.
The following is combined with fig. 5: the imaged sample was a letter "a" made of 2B pencil lead, 0.5 mm in diameter, and agar, wrapped in water as a photoacoustic signal couplant. The sample is surrounded by an annular probe frame of four ultrasonic probes, the probes are distributed with a 90-degree difference, and the probe frame is controlled by a stepping motor to rotate around the sample. In the experimental device, a pulse laser light source with the wavelength of 532 nanometers and the repetition frequency of 10 Hz, which is emitted by a high-power laser, is used for uniformly irradiating laser on an imaging sample through an optical fiber and a group of light paths. Specifically, the DAQ acquisition card used in the experiment is an oscilloscope (Tektronics) with a sampling rate of 1GSPS, and the preamplifier module for amplifying photoacoustic signals is a four-channel amplifier group.
The multi-path acoustic delay line module adopted by the embodiment has three groups of acoustic delay line modules, and the sound conductivity and the sound speed are stabilized to be 1480m/s based on water, so that the sound propagation media of the three groups of delay lines are all water. The lengths of the three groups of acoustic delay lines are 1 unit length, 2 unit lengths and 3 unit lengths respectively, the unit lengths depend on the time length for effectively separating all paths of photoacoustic signals, and can be calculated by formula (1) in the first embodiment specifically, and the unit length of the experiment is set to be 6 cm.
In the experiment, 120 paths of photoacoustic signals with different angles are collected by surrounding a sample by a stepping angle of 3 degrees in the collection process, and the scanning diameter of the annular ultrasonic probe array is 10.6 centimeters. In the experiment, 4 ultrasonic probes receive photoacoustic signals, and 30 groups of data are acquired by 1 DAQ acquisition port through a 4-in-1 data acquisition system based on acoustic delay in the signal acquisition process to obtain 120 paths of photoacoustic signals.
30 groups of signals acquired by a Delay line can obtain 120 paths of signals for image reconstruction according to a signal recovery method provided by the patent, And an image reconstruction algorithm adopted in an experiment is a classical Delay-And-Sum (Beamforming) forming algorithm.
In the imaging result, the image reconstructed by the conventional detection method is as shown in fig. 7A, and the image is clear and has obvious boundaries; the reconstructed image of the present invention based on the delay line sampling method is shown in fig. 7B, in which some images have some artifacts due to background noise, but the object contour is still distinguishable. Therefore, the removal of the signal noise is an essential step for improving the image quality after the imaging of the photoacoustic imaging system based on the multi-channel delay line module. The experimental results above well demonstrate the feasibility of the multi-channel photoacoustic signal delay line module of the present invention in the PAT system.
ExamplesFive of them
Fig. 8 is a schematic structural diagram of another electronic terminal according to an embodiment of the present invention. This example provides an electronic terminal, includes: a processor 81, a memory 82, a communicator 83; the memory 82 is connected with the processor 81 and the communicator 83 through a system bus and completes mutual communication, the memory 82 is used for storing computer programs, the communicator 83 is used for communicating with other devices, and the processor 81 is used for running the computer programs so as to enable the electronic terminal to execute the steps of the signal processing method based on the multichannel photoacoustic signal delay.
The above-mentioned system bus may be a Peripheral Component Interconnect (PCI) bus, an Extended Industry Standard Architecture (EISA) bus, or the like. The system bus may be divided into an address bus, a data bus, a control bus, and the like. For ease of illustration, only one thick line is shown, but this does not mean that there is only one bus or one type of bus. The communication interface is used for realizing communication between the database access device and other equipment (such as a client, a read-write library and a read-only library). The Memory may include a Random Access Memory (RAM), and may further include a non-volatile Memory (non-volatile Memory), such as at least one disk Memory.
The Processor may be a general-purpose Processor, and includes a Central Processing Unit (CPU), a Network Processor (NP), and the like; the Integrated Circuit may also be a Digital Signal Processor (DSP), an Application Specific Integrated Circuit (ASIC), a Field Programmable Gate Array (FPGA) or other Programmable logic device, a discrete Gate or transistor logic device, or a discrete hardware component.
EXAMPLE six
In the present embodiment, the present invention also provides a computer-readable storage medium having stored thereon a computer program which, when executed by a processor, implements the signal processing method based on delay of a multichannel photoacoustic signal.
Those of ordinary skill in the art will understand that: all or part of the steps for implementing the above method embodiments may be performed by hardware associated with a computer program. The aforementioned computer program may be stored in a computer readable storage medium. When executed, the program performs steps comprising the method embodiments described above; and the aforementioned storage medium includes: various media that can store program codes, such as ROM, RAM, magnetic or optical disks.
In summary, the present application provides a multi-channel photoacoustic signal delay apparatus, a multi-channel photoacoustic signal delay system, a multi-channel photoacoustic signal delay method, a multi-channel photoacoustic signal delay terminal, and a multi-channel photoacoustic signal delay medium. Therefore, the requirements of the PAT system on the number of the DAQ channels can be met, the system cost is reduced, the PAT system with the fixed number of the DAQ channels can achieve the purposes of reducing the scanning time during the PAT data acquisition and improving the imaging speed. Therefore, the application effectively overcomes various defects in the prior art and has high industrial utilization value.
The above embodiments are merely illustrative of the principles and utilities of the present application and are not intended to limit the application. Any person skilled in the art can modify or change the above-described embodiments without departing from the spirit and scope of the present application. Accordingly, it is intended that all equivalent modifications or changes which can be made by those skilled in the art without departing from the spirit and technical concepts disclosed in the present application shall be covered by the claims of the present application.
Claims (10)
1. A multichannel photoacoustic signal delay device is characterized in that a plurality of paths of input signals are accessed; the device comprises:
the delay units are used for accessing the input signals and outputting the input signals after delay processing;
at least one adder for adding the signals;
and after the delay processing is carried out on part or all of the multi-path input signals by the delay unit and the addition processing is carried out by the adder, the signals are output as one path of output signals.
2. The apparatus of claim 1, wherein the apparatus comprises:
a plurality of delay cells connected in series; each delay unit is connected with one input signal, and the next delay unit in the series connection is also connected with the delay signal output by the previous delay unit through an adder;
under the condition that all signals are subjected to delay processing by the delay units, the output signal of the last delay unit in the series connection is output through one output signal of the delay device; and under the condition that partial signals are subjected to delay processing by the delay units, adding an output signal of the last delay unit in the series connection and an input signal which is not subjected to delay processing by the delay units by the adder to serve as an output signal to be output.
3. The apparatus of claim 1, wherein the apparatus comprises:
a plurality of delay cells connected in parallel; each delay unit is connected with one input signal;
under the condition that all signals are subjected to delay processing by the delay units, output signals of all delay units connected in parallel are added by an adder and then are output as one path of output signal; under the condition that partial signals are delayed by the delay units, the output signals of the delay units connected in parallel and the input signals which are not delayed by the delay units are added by the adder to be output as one output signal.
4. The apparatus of claim 1, wherein the delay time of each delay unit is positively correlated to the length of the propagation medium of the acoustic wave and negatively correlated to the velocity of the acoustic wave in the propagation medium.
5. A delay cell structure, comprising:
the ultrasonic transmitting unit is used for receiving an input signal and generating corresponding ultrasonic waves;
an ultrasonic propagation medium for propagating the ultrasonic wave;
an ultrasound receiving unit for receiving the ultrasound waves propagated by the ultrasound propagation medium.
6. The delay cell structure of claim 5, wherein the delay time of the delay cell structure is positively correlated with the length of the ultrasound propagation medium and negatively correlated with the propagation velocity of the ultrasound waves in the ultrasound propagation medium.
7. A photoacoustic imaging system based on multi-channel photoacoustic signal delay, comprising:
the pulse laser generating module is used for generating laser pulses and irradiating the laser pulses to the surface of the sample;
a plurality of ultrasonic probes for performing ultrasonic testing on the sample; the ultrasonic probe is arranged on the rotary displacement table and rotates along with the rotary displacement table;
the driving motor is in driving connection with the rotary displacement table so as to adjust the receiving angle of the ultrasonic probe for receiving the laser pulse;
the multi-channel amplification module is used for receiving and amplifying ultrasonic signals from the plurality of ultrasonic probes;
the multi-channel delay module is connected with the multi-channel amplification module and outputs a path of combined signal after delay processing is carried out on the amplified multi-channel signal;
the data acquisition module is connected with the multichannel delay module to acquire the output combined signal;
and the data calculation module is connected with the data acquisition module to receive and recover the combined signal to the multiple independent signals for imaging processing.
8. A signal processing method based on multichannel photoacoustic signal delay is characterized by comprising the following steps:
acquiring an output signal of the multi-channel photoacoustic signal delaying apparatus of claim 1;
and restoring the output signals into multi-channel signals with the same number as the input signals in the digital domain according to the corresponding delay time for imaging processing.
9. A computer-readable storage medium, on which a computer program is stored, the computer program, when being executed by a processor, implementing the method for signal processing based on delay of a multichannel photoacoustic signal according to claim 8.
10. An electronic terminal, comprising: a processor and a memory;
the memory is used for storing a computer program;
the processor is configured to execute the computer program stored in the memory to cause the terminal to execute the signal processing method based on multi-channel photoacoustic signal delay of claim 8.
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