Feed-through signal dynamic active compensation control system and method

Abstract

The invention relates to a feed-through signal dynamic active compensation control system and method, and the system comprises a signal collection module which is used for collecting a magnetic nanoparticle magnetization response signal, a fundamental frequency feed-through signal, an excitation current signal and a scanning current signal through a collection card; the gradiometer coil module is used for receiving the fundamental frequency feed-through signal to carry out first-stage compensation and outputting a residual interference signal; the signal processing module is used for acquiring an initial active compensation signal according to the amplitude and phase of the residual interference signal and the relative parameters of the transformer; the active compensation module is used for processing the initial active compensation signal and obtaining a final active compensation signal to carry out secondary compensation on the residual interference signal; and the control module is used for controlling the acquisition card to output a responded analog electric signal to the magnetic particle imaging equipment and the active compensation module according to the control instruction. According to the invention, accurate compensation of the fundamental frequency feed-through signal is realized through two-stage compensation, the repeatability of the system is improved, and the complexity of system hardware design is reduced.

Description

Technical Field

[0001] This invention relates to the field of signal processing technology, and in particular to a dynamic active compensation control system and method for feedthrough signals. Background Technology

[0002] Magnetic particle imaging is a rapidly developing new medical imaging technology that uses magnetic nanoparticles as imaging tracers. Its basic principle is to apply a dynamic magnetic field to excite the magnetic nanoparticles, causing them to generate a nonlinear magnetization response near a point without an electric field. These response signals are then acquired by a receiving coil, ultimately reconstructing an image of the particle's spatial distribution. Magnetic particle imaging technology has advantages such as high sensitivity, high spatial resolution, high temporal resolution, no ionizing radiation, and fast imaging speed, and is widely used in medical and biological fields such as tumor imaging, brain nerve function imaging, angiography, perfusion monitoring, and cell tracking.

[0003] However, in magnetic particle imaging systems, the excitation magnetic field inevitably couples directly to the receiving coil, forming a strong fundamental frequency feedthrough signal with an amplitude that can be several orders of magnitude higher than the particle magnetization response signal. This strong coupling signal not only obscures the particle response but also saturates the preamplifier in the receiving link, severely interfering with the system's imaging quality.

[0004] Traditional suppression methods mainly include hardware filtering, structural shielding, and passive compensation. However, these methods usually have problems such as poor adaptability, limited compensation accuracy, complex debugging, and difficulty in real-time dynamic adjustment, which cannot meet the signal requirements of high-performance magnetic particle imaging systems for low interference and high signal-to-noise ratio.

[0005] Therefore, there is an urgent need to develop an active compensation mechanism with dynamic adjustment capability, fast response speed and high compensation accuracy, so as to further improve the magnetic particle imaging system's ability to extract weak particle signals and enhance the overall imaging performance. Summary of the Invention

[0006] The purpose of this invention is to provide a dynamic active compensation control system and method for feedthrough signals. By integrating multi-channel analog input / output components, the system can collect and analyze the fundamental frequency interference signal generated by the magnetic field in the receiving link in real time. Combined with differential compensation mechanism and adaptive feedback algorithm, the system achieves efficient suppression of feedthrough signals and complete preservation of the magnetization response signal of magnetic nanoparticles through two-stage compensation.

[0007] To achieve the above objectives, the present invention provides the following solution:

[0008] A dynamic active compensation control system for feedthrough signals, comprising:

[0009] The signal acquisition module is used to acquire the magnetization response signal, fundamental frequency feedthrough signal, excitation current signal and scanning current signal of magnetic nanoparticles through the acquisition card;

[0010] The gradient meter coil module is used to receive the fundamental frequency feedthrough signal, perform first-stage compensation, and output residual interference signal.

[0011] The signal processing module is used to obtain the amplitude and phase of the initial active compensation signal based on the amplitude and phase of the residual interference signal and the transformer relative parameters;

[0012] An active compensation module is used to process the initial active compensation signal to obtain a final active compensation signal for secondary compensation of the residual interference signal;

[0013] The control module is used to control the acquisition card to output a corresponding analog electrical signal to the magnetic particle imaging device and the active compensation module according to the control command.

[0014] Optionally, the acquisition card includes analog input terminals AI0, AI1, and AI2;

[0015] The analog input terminal AI0 is used to acquire the current signal in the excitation channel in real time and perform digital processing to generate corresponding current data to monitor the amplitude of the excitation magnetic field.

[0016] The analog input terminal AI1 is used to acquire the current signal in the scanning channel in real time, and after digital processing, generate the corresponding current data to monitor the amplitude of the scanning magnetic field.

[0017] The analog input terminal AI2 is used to acquire the received signal of the amplified receiving coil in real time, wherein the received signal includes the fundamental frequency feedthrough signal and the magnetization response signal of the magnetic nanoparticles.

[0018] Optionally, the acquisition card includes analog output terminals AO0, AO1, and AO2;

[0019] The analog output terminal AO0 is used to generate a voltage signal with the required frequency and amplitude for the excitation magnetic field. The voltage signal required for the excitation magnetic field is amplified by power and then input to the excitation coil in the magnetic particle imaging device.

[0020] The analog output terminal AO1 is used to generate a voltage signal with the required frequency and amplitude for scanning the magnetic field. The voltage signal required for scanning the magnetic field is amplified and then input to the scanning coil in the magnetic particle imaging device.

[0021] The analog output terminal AO2 is used to input the active compensation signal, after power amplification, into the primary coil of the differential transformer in the active compensation module.

[0022] Optionally, the active compensation module includes two sets of transformers, wherein the secondary coils are respectively connected to the two ends of the receiving coil.

[0023] This embodiment also provides a dynamic active compensation control method for feedthrough signals, including:

[0024] The magnetic nanoparticle magnetization response signal, fundamental frequency feedthrough signal, excitation current signal, and scanning current signal are acquired using a data acquisition card.

[0025] The baseband feedthrough signal is received for first-stage compensation, and the residual interference signal is output.

[0026] Based on the amplitude and phase of the residual interference signal and the transformer relative parameters, the amplitude and phase of the initial active compensation signal are obtained;

[0027] The amplitude and phase of the initial active compensation signal are processed to obtain the final active compensation signal for secondary compensation of the residual interference signal;

[0028] According to the control command, the acquisition card outputs a corresponding analog electrical signal to the magnetic particle imaging device and the active compensation module.

[0029] Optionally, secondary compensation may be provided, including:

[0030] ;

[0031] in, This is the particle magnetization response signal. This is a residual interference signal. This is the final secondary active compensation signal. This is the compensated signal.

[0032] Optionally, the final active compensation signal is:

[0033] ;

[0034] in, The amplitude of the analog output signal AO2 from the acquisition card after passing through the compensation signal link. This refers to the phase shift after passing through the compensated signal link.

[0035] Optionally, the acquisition of magnetization response signals, fundamental frequency feedthrough signals, excitation current signals, and scanning current signals of magnetic nanoparticles includes:

[0036] The excitation signal is processed by the first power amplifier and then input to the excitation coil to generate an excitation magnetic field, which in turn generates an excitation current signal.

[0037] The scanning signal is amplified by the second power amplifier and then transmitted to the scanning coil. The scanning coil generates a moving scanning magnetic field, which in turn generates a scanning current signal.

[0038] Magnetic nanoparticles are placed in the central region of the receiving coil, and under the action of excitation and scanning magnetic fields, a magnetization response signal containing fundamental frequency and higher harmonic components is generated.

[0039] The beneficial effects of this invention are as follows: The magnetic particle imaging dynamic compensation control system proposed in this invention adopts a "two-stage compensation + real-time feedback" structure, which can effectively suppress the fundamental frequency feedthrough signal in the receiving link. When the particle has not entered the imaging area, the system completes the amplitude and phase response calibration of the compensation path through linear scanning, and then dynamically generates an active compensation signal with optimal amplitude and phase matching, achieving high-precision real-time suppression of coupling interference. Compared with the traditional passive compensation method, this method can avoid compensation failure caused by environmental changes, hardware parameter drift, etc., and ensures accurate cancellation of the compensation signal and the interference signal in phase and amplitude, thereby significantly improving compensation efficiency and system robustness. On the other hand, through the real-time feedback control algorithm embedded in the signal processing module, this system can automatically update the compensation signal parameters in each feedback cycle, greatly reducing the difficulty of system debugging and improving compensation accuracy. Under high sensitivity conditions, it can still effectively improve the imaging signal-to-noise ratio and optimize the image reconstruction quality. Attached Figure Description

[0040] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0041] Figure 1 This invention provides a dynamic active compensation control system for feedthrough signals.

[0042] Figure 2 This is a signal flow diagram of two-stage compensation according to an embodiment of the present invention. Detailed Implementation

[0043] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0044] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0045] This embodiment proposes a dynamic active compensation control system for feedthrough signals, including:

[0046] The signal acquisition module is used to acquire the magnetization response signal, fundamental frequency feedthrough signal, excitation current signal and scanning current signal of magnetic nanoparticles through the acquisition card;

[0047] The gradient meter coil module is used to receive the fundamental frequency feedthrough signal, perform first-stage compensation, and output residual interference signal.

[0048] The signal processing module is used to obtain the amplitude and phase of the initial active compensation signal based on the amplitude and phase of the residual interference signal and the transformer relative parameters;

[0049] An active compensation module is used to process the initial active compensation signal to obtain a final active compensation signal for secondary compensation of the residual interference signal;

[0050] The control module is used to control the acquisition card to output a corresponding analog electrical signal to the magnetic particle imaging device and the active compensation module according to the control command.

[0051] Specifically, the gradient meter coil module is used to perform the first stage of compensation on the fundamental frequency feedthrough signal received by the receiving coil, and to suppress feedthrough interference through differentially placed compensation coils;

[0052] The signal acquisition module is used to acquire the magnetization response signal, excitation current signal and scanning current signal of the magnetic nanoparticles after active compensation, and transmit them to the central processing unit.

[0053] The signal processing module is used to calculate the amplitude and phase of the residual interference signal to obtain the amplitude and phase of the initial active compensation signal.

[0054] The active compensation module receives the initial active compensation signal and generates a compensation analog electrical signal with opposite phase to the residual interference signal. The initial active compensation signal generated by the signal processing module is input to the primary coil of a set of identical magnetic ring transformers. The secondary coils of the transformers are connected to both ends of the receiving coil. After isolation and amplification by the transformers, the signal is differentially connected to both ends of the receiving coil to achieve a second stage of compensation, maximizing the dynamic cancellation of the induced coupling signal of the excitation magnetic field in the receiving coil during imaging.

[0055] The control module is used to process the control commands sent by the host computer. According to the commands, it controls the acquisition card to output the analog electrical signal that generates the excitation magnetic field, the analog electrical signal that generates the scanning magnetic field, and the active compensation analog electrical signal, which are then transmitted to the excitation coil, the scanning coil, and the active compensation module respectively through the power amplifier.

[0056] Furthermore, the acquisition card includes analog input terminals AI0, AI1, and AI2;

[0057] The analog input terminal AI0 is used to acquire the current signal in the excitation channel in real time and perform digital processing to generate corresponding current data to monitor the amplitude of the excitation magnetic field.

[0058] The analog input terminal AI1 is used to acquire the current signal in the scanning channel in real time, and after digital processing, generate the corresponding current data to monitor the amplitude of the scanning magnetic field.

[0059] The analog input terminal AI2 is used to acquire the received signal of the amplified receiving coil in real time, wherein the received signal includes the fundamental frequency feedthrough signal and the magnetization response signal of the magnetic nanoparticles.

[0060] Furthermore, the acquisition card includes analog output terminals AO0, AO1, and AO2;

[0061] The analog output terminal AO0 is used to generate a voltage signal with the required frequency and amplitude for the excitation magnetic field. The voltage signal required for the excitation magnetic field is amplified by power and then input to the excitation coil in the magnetic particle imaging device.

[0062] The analog output terminal AO1 is used to generate a voltage signal with the required frequency and amplitude for scanning the magnetic field. The voltage signal required for scanning the magnetic field is amplified and then input to the scanning coil in the magnetic particle imaging device.

[0063] The analog output terminal AO2 is used to input the active compensation signal, after power amplification, into the primary coil of the differential transformer in the active compensation module.

[0064] Furthermore, the active compensation module includes two sets of transformers with roughly the same parameters, whose secondary coils are respectively connected to the two ends of the receiving coil to achieve differential compensation.

[0065] Furthermore, a bandpass filter is provided in the analog output terminal AO2 signal path of the acquisition card to improve the quality of the active compensation signal.

[0066] The following section provides a further explanation of the system used in this example:

[0067] like Figure 1 As shown in the figure, this embodiment discloses a dynamic active compensation control system for feedthrough signals, which includes:

[0068] The gradient meter coil module is used to perform the first stage of compensation on the fundamental frequency feedthrough signal received by the receiving coil through differential and reverse compensation coils placed on both sides of the receiving coil, and then obtain the residual interference signal after the first stage of compensation.

[0069] The signal processing module calculates the strength of the fundamental frequency signal and the required active compensation signal. It utilizes a real-time feedback dynamic compensation algorithm, whose core calculation is based on the physical relationship: "Required active compensation signal = Residual interference signal ÷ Transformer relative parameters." By expressing and operating the signal in the complex domain, it accurately calculates and updates the corrected output. The original input signal is the amplitude and phase information of the current residual interference signal, which is mapped to the complex domain using the transformer relative parameters. Then, the required active compensation signal is calculated using complex domain multiplication and division. It's important to note that after calculating the net compensation signal, the phase needs to be flipped by 180° for correction. Subsequently, the new amplitude and phase of the current residual interference signal are extracted and fed back to the external main program as new inputs, implementing the dynamic feedback mechanism. Because the residual interference signal is updated in real time, the compensation effect is continuously corrected, giving the entire system good stability and tracking capability. The initial active compensation signal required for each feedback is calculated.

[0070] The active compensation module is used to process the initial active compensation signal to generate a compensation analog electrical signal that is out of phase with the residual interference signal. A set of transformers with the same parameters are connected to the two ends of the receiving coil in a differential form to achieve the second-level compensation, which dynamically cancels the induced coupling signal of the excitation magnetic field in the receiving coil during the imaging process to the maximum extent.

[0071] The signal acquisition module is used to acquire the magnetization response signal, excitation current signal and scanning current signal of the magnetic nanoparticles, and transmit them to the central processing unit.

[0072] The control module is used to process the control commands sent by the host computer, and control the acquisition card to output corresponding analog electrical signals according to the commands. These signals are then transmitted to the excitation coil and the active compensation module through the power amplifier.

[0073] The feedthrough signal dynamic active compensation control system proposed in this embodiment consists of multiple sub-modules, including a gradient meter coil module, an active compensation module, a signal acquisition module, and a control module. These modules work together to construct a magnetic particle imaging signal compensation system with high interference suppression capability and real-time dynamic response capability.

[0074] Specifically, the system uses a data acquisition card as the core unit for analog signal input and output, outputting excitation, scanning, and active compensation signals respectively. The excitation and scanning signals are amplified and transmitted to the excitation and scanning coils respectively, thereby generating an excitation magnetic field and a scanning magnetic field for spatial encoding within the imaging area, achieving magnetization and spatial positioning of magnetic nanoparticles. Simultaneously, the receiving coil senses the nonlinear magnetization response signal of the magnetic nanoparticles and also receives the fundamental frequency feedthrough signal directly coupled from the excitation magnetic field.

[0075] To reduce the coverage of weak particle signals by feedthrough interference, this system employs a two-stage compensation structure. The first layer is the gradient meter coil module, whose compensation coils are arranged in a differential structure, forming a common-mode interference suppression circuit together with the receiving coil. This can eliminate most of the low-frequency coupling components caused by the excitation field at the hardware level. The second layer is the active compensation module. Its core is that the central processing unit calculates the amplitude and phase of the corresponding compensation signal based on the acquired coupling signal, outputs a set of inverted compensation waveform signals through the acquisition card channel, and injects them into both ends of the receiving coil through a differential transformer structure to achieve dynamic suppression of residual interference.

[0076] At the end of the receiving link, the signal is first pre-amplified by a low-noise differential amplifier, and then the excitation current, scanning current, and particle signal are acquired through the analog input channel of the acquisition card and transmitted to the control unit for real-time processing. The signal processing module calculates the optimal compensation signal parameters based on the amplitude and phase response of the compensation path obtained through linear scanning, according to the residual interference signal, and updates the output periodically in real time. This allows the compensation signal to adaptively adjust with changes in the system state, effectively avoiding compensation mismatch problems caused by factors such as phase drift.

[0077] This system, through multi-channel collaboration, high-speed closed-loop feedback, and dual compensation structure, ensures high-fidelity acquisition of particle signals even under strong coupling conditions, significantly improving the sensitivity and stability of the imaging system. It also possesses strong portability and system integration capabilities, making it suitable for high-resolution magnetic particle imaging experiments in various scenarios.

[0078] In one specific embodiment, the system further includes: analog input terminals AI0, AI1, and AI2 of the acquisition card, and analog output terminals AO0, AO1, and AO2 of the acquisition card; wherein,

[0079] The analog input terminal AI0 is used to acquire the current signal in the excitation channel in real time, and digitize the signal to generate corresponding current data to monitor the amplitude of the excitation magnetic field.

[0080] The analog input terminal AI1 is used to acquire the current signal in the scanning channel in real time, and digitize the signal to generate corresponding current data to monitor the amplitude of the scanning magnetic field.

[0081] The analog input terminal AI2 is used to acquire the received signal of the receiving coil after being amplified by the low-noise amplifier (LNA) in real time. The received signal includes the fundamental frequency feedthrough signal and the magnetization response signal of the magnetic nanoparticles.

[0082] The analog output terminal AO0 is used to generate a voltage signal with the required frequency and amplitude for the excitation magnetic field. The required voltage signal is amplified by power and then input to the excitation coil in the magnetic particle imaging device.

[0083] The analog output terminal AO1 is used to generate a voltage signal with the required frequency and amplitude for scanning the magnetic field. The required voltage signal is amplified by power and then input to the scanning coil in the magnetic particle imaging device.

[0084] The analog output terminal AO2 is used to generate the active compensation signal with corresponding amplitude and phase calculated by the signal processing module. The required active compensation signal is amplified and then input to the primary coil of the differential transformer in the active compensation module.

[0085] This embodiment also provides a dynamic active compensation control method for feedthrough signals, including:

[0086] The magnetic nanoparticle magnetization response signal, fundamental frequency feedthrough signal, excitation current signal, and scanning current signal are acquired using a data acquisition card.

[0087] The baseband feedthrough signal is received for first-stage compensation, and the residual interference signal is output.

[0088] Based on the amplitude and phase of the residual interference signal and the transformer relative parameters, the amplitude and phase of the initial active compensation signal are obtained;

[0089] The amplitude and phase of the initial active compensation signal are processed to obtain the final active compensation signal for secondary compensation of the residual interference signal;

[0090] According to the control command, the acquisition card outputs a corresponding analog electrical signal to the magnetic particle imaging device and the active compensation module.

[0091] Specifically, the control module controls the multiple analog output channels of the data acquisition card to output excitation signals, scanning signals, and active compensation signals respectively;

[0092] The excitation signal is processed by the first power amplifier and then input to the excitation coil, thereby generating an excitation magnetic field and an excitation current signal.

[0093] The scanning signal is amplified by the second power amplifier and transmitted to the scanning coil. The scanning coil generates a moving scanning magnetic field and a scanning current signal. The scanning magnetic field is used to move the field-free point to traverse the imaging area and realize spatial information encoding.

[0094] Magnetic nanoparticles are placed in the central region of the receiving coil and generate a magnetization response signal containing fundamental frequency and higher harmonic components under the action of excitation and scanning magnetic fields.

[0095] The receiving coil receives the baseband feedthrough signal and performs the first stage of compensation on the baseband feedthrough signal through the compensation coil, outputting the residual interference signal;

[0096] The residual fundamental frequency interference signal is input to the low noise amplifier through the active compensation module, and after amplification, it is acquired by the analog input terminal of the acquisition card and transmitted to the signal processing module.

[0097] The signal processing module performs amplitude and phase analysis on the received signal, extracts the fundamental frequency residual component, and uses a real-time feedback adaptive algorithm to calculate the amplitude and phase parameters of the required active compensation signal. The control module generates the corresponding initial active compensation signal based on the feedback calculation results and outputs the signal to the input of the active compensation module through the analog output terminal of the acquisition card. After processing the initial active compensation signal, the active compensation module applies it to the receiving link in a differential injection manner to perform a second-level compensation on the residual interference signal, further suppressing the interference component.

[0098] The final output magnetization response signal is processed by a low-noise amplifier to obtain particle magnetization response signals containing harmonic components of various orders, which are then used for subsequent spectrum extraction and image reconstruction processing.

[0099] Furthermore, secondary compensation will be provided, including:

[0100] ;

[0101] in, This is the particle magnetization response signal. This is a residual interference signal. This is the final active compensation signal.

[0102] Furthermore, the final active compensation signal is:

[0103] ;

[0104] in, The amplitude of the analog output signal AO2 from the acquisition card after passing through the compensation signal link. This refers to the phase shift after passing through the compensated signal link.

[0105] Furthermore, the acquisition of magnetization response signals, fundamental frequency feedthrough signals, excitation current signals, and scanning current signals of magnetic nanoparticles includes:

[0106] The excitation signal is processed by the first power amplifier and then input to the excitation coil to generate an excitation magnetic field. The excitation magnetic field excites the magnetic nanoparticles to generate a magnetic nanoparticle magnetization response signal.

[0107] The scanning signal is amplified by the second power amplifier and then transmitted to the scanning coil. The scanning coil generates a moving scanning magnetic field, which in turn generates a scanning current signal.

[0108] Magnetic nanoparticles are placed in the central region of the receiving coil, and under the action of excitation and scanning magnetic fields, a magnetization response signal containing fundamental frequency and higher harmonic components is generated.

[0109] The method of this embodiment will be further described below:

[0110] A dynamic active compensation control method for feedthrough signals includes the following steps:

[0111] The control module controls the multiple analog output channels of the data acquisition card to output excitation signals, scanning signals and active compensation signals respectively;

[0112] The excitation signal is processed by the first power amplifier and then input to the excitation coil, thereby generating an excitation magnetic field. This excitation magnetic field is used to excite the magnetic nanoparticles to generate a nonlinear magnetization response signal.

[0113] The scanning signal is amplified by the second power amplifier and transmitted to the scanning coil. The scanning coil generates a moving scanning magnetic field, which is used to move the field-free point to traverse the imaging area and realize spatial information encoding.

[0114] Magnetic nanoparticles are placed in the central region of the receiving coil and generate a magnetization response signal containing fundamental frequency and higher harmonic components under the action of excitation and scanning magnetic fields.

[0115] The receiving coil receives the baseband feedthrough signal and performs the first stage of compensation on the baseband feedthrough signal through the compensation coil, outputting the residual interference signal;

[0116] The residual fundamental frequency interference signal is input to the low noise amplifier through the active compensation module, and after amplification, it is acquired by the analog input terminal of the acquisition card and transmitted to the signal processing module.

[0117] The signal processing module performs amplitude and phase analysis on the received signal, extracts the residual fundamental frequency component, and uses a real-time feedback adaptive algorithm to calculate the amplitude and phase parameters of the required active compensation signal. The control module generates the corresponding initial active compensation signal based on the feedback calculation results and outputs the signal to the input of the active compensation module through the analog output terminal of the acquisition card. After processing the initial active compensation signal, the active compensation module applies the active compensation signal to the receiving link in a differential injection manner to perform a second-level compensation on the residual fundamental frequency interference signal, further suppressing the interference component.

[0118] The final output magnetization response signal is processed by a low-noise amplifier to obtain a particle magnetization response signal containing harmonic components of each order, which is then used for subsequent spectrum extraction and image reconstruction processing.

[0119] like Figure 2 The diagram shown illustrates the signal flow chart for two-stage compensation. The system operation flow consists of three parts: gradiometer coil calibration, active compensation signal conditioning, and particle signal measurement. These include:

[0120] Step S10: Gradient meter coil calibration. Without placing magnetic nanoparticles, the system first enters calibration mode. The control module sets the initial magnetic field strengths for the excitation and scan signals, while the receiving channel remains connected but without injecting an active compensation signal. The receiving coil voltage U is recorded via the data acquisition module. d and the compensation coil voltage U c ,pass Acquire the fundamental frequency feedthrough signal in the receiving channel. Then, after fine-tuning the number of turns in the gradient meter compensation coil, compare the output voltage of the residual interference signal before and after the first stage of compensation. Trend of change. Through multiple iterative adjustments, the residual interference signal output voltage is gradually minimized until the set voltage threshold is met, thus achieving the first stage of hardware compensation and minimizing the baseband signal and common-mode interference signal in the receiving link.

[0121] Step S20: Active Compensation Adjustment. Without placing magnetic nanoparticles, the active compensation module is activated. The system initially sets the AO2 output to a linearly varying signal, and sequentially acquires the output of the receiving coil under the current parameters. The control module uses this data to calculate the relative amplification and phase shift of the current receiving link. Based on the fitted transfer function model, the AO2 output parameters are automatically adjusted, and the LNA output response is monitored in real time, dynamically feedback is provided until the residual fundamental frequency signal is minimized, thus initializing the second-stage dynamic compensation.

[0122] Step S30: Particle Measurement. After completing two-stage compensation, the system enters the particle signal measurement stage. First, imaging parameters such as the field of view, excitation magnetic field frequency, and excitation magnetic field strength are set. The system's background noise is obtained through air measurement. The magnetic nanoparticles were then moved to a point with no electric field for data acquisition. The receiving coil induced a signal containing the particle magnetization response and the system's background noise. The signal, after amplification and sampling, enters the signal processing module. The signal processing module automatically subtracts the system background noise obtained from the previous airborne measurement from it to obtain the particle signal. The harmonics of different frequency components are extracted. Finally, the extracted spectrum is used for subsequent imaging and visualization output.

[0123] Furthermore, the signal input from the LNA to the AI2 port of the acquisition card is analyzed, and the expression of the signal after processing by the receiving link is as follows:

[0124] ;

[0125] in, This refers to the particle magnetization response signal. This is a residual interference signal. The active compensation signal, This is the compensated signal.

[0126] like Then the fundamental frequency feedthrough signal is suppressed, and a voltage signal containing only the particle magnetization response signal can be obtained. .

[0127] Analyzing the active compensation module, the expression for the compensation signal output by the active compensation module is as follows:

[0128] ;

[0129] in, The amplitude of the analog output signal AO2 from the acquisition card after passing through the compensation signal link is given by the expression. This expression describes the final compensated voltage signal modulated by the active compensation module. Both its amplitude and phase are dynamically adjusted according to a feedback algorithm to achieve high-precision differential interference cancellation. The compensation signal link amplifies the output signal from the analog output AO2. This refers to the phase offset after passing through the compensation signal link.

[0130] Specifically, step S10 includes:

[0131] S11: Before starting the system, confirm that the magnetic nanoparticles are not placed in the imaging area and ensure that the current working state is a no-response background. The control module initializes the signal source module and sets the operating frequency and current amplitude of the excitation coil;

[0132] S12: The excitation signal is amplified and then used to drive the excitation coil to generate an excitation magnetic field; the receiving coil and LNA form a receiving channel and begin to acquire the baseband feedthrough signal.

[0133] S13: Record the receiving coil voltage U through the data acquisition module. d and the compensation coil voltage U c To acquire residual interference signals in the receiving channel.

[0134] S14: Adjust the number of turns of the compensation coil. After each adjustment, remeasure the residual interference signal and observe its changing trend. If the amplitude of the residual interference signal is lower than the set threshold, the first stage of compensation is completed, and the process proceeds to the next stage.

[0135] Step S20 includes:

[0136] S21: The control module controls the AO2 output terminal, setting an initial sinusoidal signal with a very small amplitude as a reference compensation signal; the initial AO2 output is set to a linearly changing signal, and the output of the receiving coil is acquired sequentially. The data acquisition system is simultaneously started to acquire the output of the receiving channel.

[0137] S22: Extract the amplification factor and phase of the compensation end with respect to the fundamental frequency signal, and compare it with the excitation source signal to obtain the relative amplification factor and phase shift, which are used as the calculation reference for the subsequent active compensation signal.

[0138] S23: Measure residual interference signal U E According to U E The active compensation signal is iteratively adjusted by calculating the amplification factor and phase at the compensation end. The amplitude and phase of the active compensation signal are calculated based on the path model and injected into both ends of the receiving coil for differential compensation. The compensated received signal is then acquired, residual interference is calculated, and the amplitude and phase are further optimized. The AO2 output is updated to achieve closed-loop adaptive control.

[0139] Step S30 includes:

[0140] S31: Set imaging parameters and output signals. According to preset instructions, the control module outputs excitation and scanning signals from analog output channels AO0 and AO1 respectively. After being amplified by power amplifiers, these signals are applied to the excitation coil and scanning coil respectively to move the field-free point for spatial encoding.

[0141] S32: Without placing magnetic nanoparticles, the control module maintains the excitation and scanning magnetic field unchanged, and acquires the current system output signal and the system's background noise u through the receiving coil. b The data is then processed by an LNA and input into the analog acquisition channel AI2, while retaining the background noise data.

[0142] S33: After completing the airborne measurement, the magnetic nanoparticle sample is moved into the central region of the magnetic field, at which point the particles generate a nonlinear magnetization response. Keeping the excitation and scanning magnetic field parameters constant, the signal output at this point is acquired to obtain the total signal containing the particle magnetization response and the system background noise. Simultaneously, the excitation current and scanning current signals are acquired and input to channels AI0 and AI1, respectively. The system background signal acquired in step S32 is differentially subtracted from the particle magnetization response signal containing the system background signal to obtain the net particle magnetization response signal. Its spectral components are extracted, and an inversion reconstruction algorithm is used to reconstruct the spatial distribution image of the particles.

[0143] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made to the technical solutions of the present invention by those skilled in the art without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A feed signal dynamic active compensation control system, characterized by, The method comprises the steps of: The signal acquisition module is used for acquiring the magnetization response signal of magnetic nanoparticles, the base frequency feed signal, the excitation current signal and the scanning current signal through the acquisition card; The gradient meter coil module is used for receiving the base frequency feed signal for first-stage compensation and outputting a residual interference signal; The signal processing module is used for acquiring the amplitude and phase of the initial active compensation signal according to the amplitude and phase of the residual interference signal and the relative parameters of the transformer; The active compensation module is used for processing the initial active compensation signal to obtain a final active compensation signal for second-stage compensation of the residual interference signal; The control module is used for controlling the acquisition card to output the responsive analog electrical signal to the magnetic particle imaging device and the active compensation module according to the control instruction.

2. The feed signal dynamic active compensation control system of claim 1, wherein, The acquisition card comprises analog input terminals AI0, AI1 and AI2; The analog input terminal AI0 is used for acquiring the current signal in the excitation channel in real time and performing digital processing to generate corresponding current data for monitoring the excitation magnetic field amplitude; The analog input terminal AI1 is used for acquiring the current signal in the scanning channel in real time and performing digital processing to generate corresponding current data for monitoring the scanning magnetic field amplitude; The analog input terminal AI2 is used for acquiring the amplified receiving signal of the receiving coil in real time, wherein the receiving signal comprises the base frequency feed signal and the magnetization response signal of the magnetic nanoparticles.

3. The feed signal dynamic active compensation control system of claim 1, wherein, The acquisition card comprises analog output terminals AO0, AO1 and AO2; The analog output terminal AO0 is used for generating a voltage signal of the required frequency and amplitude of the excitation magnetic field, and the required voltage signal of the excitation magnetic field is input to the excitation coil in the magnetic particle imaging device after power amplification; The analog output terminal AO1 is used for generating a voltage signal of the required frequency and amplitude of the scanning magnetic field, and the required voltage signal of the scanning magnetic field is input to the scanning coil in the magnetic particle imaging device after power amplification; The analog output terminal AO2 is used for inputting the active compensation signal to the primary coil of the differential transformer in the active compensation module after power amplification.

4. The feed signal dynamic active compensation control system of claim 1, wherein, The active compensation module comprises two groups of transformers, wherein the secondary coils are connected to the two ends of the receiving coil, respectively.

5. A method of controlling a dynamic active feed signal compensation according to any one of claims 1-4, characterized by The method comprises the steps of: acquiring the magnetization response signal of magnetic nanoparticles, the base frequency feed signal, the excitation current signal and the scanning current signal through the acquisition card; receiving the base frequency feed signal for first-stage compensation and outputting a residual interference signal; acquiring the amplitude and phase of the initial active compensation signal according to the amplitude and phase of the residual interference signal and the relative parameters of the transformer; processing the amplitude and phase of the initial active compensation signal to obtain a final active compensation signal for second-stage compensation of the residual interference signal; controlling the acquisition card to output the responsive analog electrical signal to the magnetic particle imaging device and the active compensation module according to the control instruction.

6. The feed signal dynamic active compensation control method of claim 5, wherein, The second-stage compensation comprises: ； wherein, is a particle magnetization response signal, is a residual interference signal, is a final active compensation signal, is a compensated signal.

7. The feed signal dynamic active compensation control method of claim 5, wherein, The final active compensation signal is: ； wherein, is the amplitude of the signal output from the analog output AO2 of the acquisition card after the compensation signal link, is the phase shift after the compensation signal link.

8. The feed signal dynamic active compensation control method of claim 5, wherein, acquiring the magnetization response signal of magnetic nanoparticles, the base frequency feed signal, the excitation current signal and the scanning current signal comprises: inputting the excitation signal to the excitation coil after processing by the first power amplifier to generate an excitation magnetic field and generate an excitation current signal; The scanning signal is amplified by the second power amplifier and transmitted to the scanning coil, and the scanning coil generates a moving scanning magnetic field to generate a scanning current signal; The magnetic nanoparticles are placed in the center area of the receiving coil, and under the action of the excitation and scanning magnetic field, a magnetization response signal containing a fundamental frequency and a high-order harmonic component is generated.

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