Magnetic Particle Imaging Method Based on Active Filter and Related Equipment

Abstract

The present application discloses a magnetic particle imaging method based on an active filter and related devices. The method includes: receiving a first excitation signal generated by a signal generator, amplifying the first excitation signal through a power amplifier, and outputting it to a drive coil to generate a changing magnetic field. The magnetic nanoparticles in the drive coil have their magnetic moments changed under the excitation of the changing magnetic field, generating magnetic particle signals; receiving a current signal induced by a receiving coil corresponding to the drive coil. The current signal includes a second excitation signal with the same frequency as the first excitation signal induced by the receiving coil based on the first excitation signal and the magnetic particle signals; performing signal processing on the current signal through an active double-T notch filter to filter out the second excitation signal corresponding to the stopband of the active double-T notch filter, and reconstructing an imaging map of the magnetic particle concentration distribution based on the remaining magnetic particle signals. That is, the signal-to-noise ratio of magnetic particle imaging is improved, achieving a better imaging effect.

Description

Technical Field

[0001] This application relates to the field of medical imaging, and particularly to a magnetic particle imaging method based on an active filter and related devices. Background Art

[0002] MPI imaging (Magnetic Particle Imaging) mainly uses a selection field to generate a Field Free Region (FFR), uses a focusing field to quickly move the field free region, and uses an excitation field (driving field) to excite the magnetic orientation of magnetic nanoparticles in the field free region to generate high-frequency harmonic signals. The high-frequency harmonic signals are received by a receiving coil, and the spatial distribution image of the concentration of magnetic nanoparticles inside the living body is obtained through image reconstruction.

[0003] During magnetic particle imaging, it is necessary to remove interference signals to ensure the accuracy of the reconstructed magnetic particle concentration distribution map. Currently, the method for removing interference signals is to suppress the excitation signal through a band-stop filter. However, the stop band of a general passive band-stop filter is relatively large, and while filtering the excitation signal, it also filters some magnetic particle signals. How to minimize the influence of the filter on magnetic particle signals is a challenging task.

[0004] To filter the excitation signal, the commonly used methods are gradient receiving coils and cancellation methods. The cancellation method is to add a signal in the signal receiving chain that has the same frequency and amplitude as the excitation signal but a phase difference of 180 degrees. This method requires accurate phase adjustment to achieve better results. The method of gradient receiving coils is to set the geometric structure of the coil to achieve the filtering effect. This method depends on the reasonable design of the coil and can only be applied to one-dimensional imaging devices. Therefore, there is a problem of poor signal processing effect in existing magnetic particle imaging, which further leads to a low imaging signal-to-noise ratio. Summary of the Invention

[0005] In view of this, embodiments of this application provide a magnetic particle imaging method based on an active filter and related devices, aiming to solve the technical problem of low signal-to-noise ratio in existing magnetic particle imaging.

[0006] Embodiments of this application provide a magnetic particle imaging method based on an active filter, which is applied to a magnetic particle imaging system based on an active filter. The magnetic particle imaging system based on an active filter includes a signal generator, a power amplifier, and an active bi-T notch filter. The method includes:

[0007] Receive a first excitation signal generated by the signal generator, amplify the first excitation signal through the power amplifier, and output it to the drive coil to generate a changing magnetic field. The magnetic nanoparticles within the drive coil have their magnetic moments changed under the excitation of the changing magnetic field, generating a magnetic particle signal;

[0008] Receive a current signal induced by a receiving coil corresponding to the drive coil. The current signal includes a second excitation signal with the same frequency as the first excitation signal induced by the receiving coil based on the first excitation signal and the magnetic particle signal;

[0009] Perform signal processing on the current signal through the active double-T notch filter, filter out the second excitation signal corresponding to the stopband of the active double-T notch filter, and reconstruct an imaging map of the magnetic particle concentration distribution based on the remaining magnetic particle signal.

[0010] In a possible implementation manner of the present application, the magnetic particle imaging system based on the active filter further includes a low-noise amplifier and an analog-to-digital converter.

[0011] The step of performing signal processing on the current signal through the active double-T notch filter, filtering out the second excitation signal corresponding to the stopband of the active double-T notch filter, and reconstructing an imaging map of the magnetic particle concentration distribution based on the remaining magnetic particle signal includes:

[0012] Perform signal processing on the current signal through the active double-T notch filter, filter out the second excitation signal corresponding to the stopband of the active double-T notch filter, and obtain a filtered magnetic particle signal;

[0013] Amplify the magnetic particle signal through the low-noise amplifier, and the processed magnetic particle signal is converted into a digital signal through the analog-to-digital converter;

[0014] Reconstruct an imaging map of the magnetic particle concentration distribution based on the digital signal.

[0015] In a possible implementation manner of the present application, the step of performing signal processing on the current signal through the active double-T notch filter, filtering out the second excitation signal corresponding to the stopband of the active double-T notch filter, and obtaining a filtered magnetic particle signal includes:

[0016] Obtain the signal frequency of the first excitation signal;

[0017] According to the signal frequency, determine the resistance value and capacitance value in the active double-T notch filter;

[0018] Adjust the quality factor of the active double-T notch filter based on the resistance value and capacitance value, and obtain the magnetic particle signal after the active double-T notch filter corresponding to the highest quality factor processes the current signal;

[0019] Wherein, the quality factor represents the stopband size of the active double-T notch filter.

[0020] In a possible implementation manner of the present application, it is characterized in that the active double-T notch filter is composed of an RC low-pass filter, an RC high-pass filter, and an operational amplifier feedback circuit.

[0021] In a possible implementation manner of the present application, the circuit diagrams of the RC low-pass filter and the RC high-pass filter include a first resistor and a second resistor, and the first resistor is connected to the positive power supply; the first resistor and the second resistor are connected in series, and a first capacitor is connected between the first resistor and the second resistor, and the other end of the first capacitor is grounded; a second capacitor is connected in parallel to the first resistor, the second capacitor is connected in series with a third resistor, the third resistor is connected in parallel with the first capacitor, and the other end of the third resistor is grounded; a third capacitor is connected in parallel to the second resistor, the third capacitor is connected in series with the second capacitor, and the other end of the third capacitor is grounded.

[0022] In a possible implementation manner of the present application, the operational amplifier feedback circuit includes a first amplifier and a second amplifier. The positive power supply terminal of the first amplifier is electrically connected to the output terminals of the second resistor and the third capacitor, and the negative power supply terminal of the first amplifier is electrically connected to the output terminal of the first amplifier; the output terminal of the first amplifier is connected in series with a fourth resistor and a fifth resistor, and the other end of the fifth resistor is grounded; the output terminal of the second amplifier is electrically connected to the output terminals of the first capacitor and the third resistor, the negative power supply terminal of the second amplifier is electrically connected to the output terminal of the second amplifier, and the positive power supply terminal of the second amplifier is electrically connected to the output terminal of the fourth resistor.

[0023] The present application also provides a magnetic particle imaging system based on an active filter. The system includes a signal generation subsystem and a signal reception subsystem. The signal generation subsystem includes a signal generator, a power amplifier, and a drive coil. The signal generation subsystem is used to receive a first excitation signal generated by the signal generator. The first excitation signal is amplified by the power amplifier and output to the drive coil to generate a changing magnetic field. The magnetic nanoparticles in the drive coil generate a magnetic particle signal under the excitation of the changing magnetic field;

[0024] The signal receiving subsystem includes an active double-T notch filter, a receiving coil, a low-noise amplifier, and an analog-to-digital converter. The signal receiving subsystem is used to receive the current signal induced by the receiving coil corresponding to the driving coil. The current signal includes a second excitation signal with the same frequency as the first excitation signal induced by the receiving coil based on the first excitation signal and a magnetic particle signal. The active double-T notch filter is used to process the current signal to filter out the second excitation signal corresponding to the stopband of the active double-T notch filter, and an imaging map of the magnetic particle concentration distribution is reconstructed based on the remaining magnetic particle signal.

[0025] The signal receiving subsystem is also used to process the current signal through the active double-T notch filter to filter out the second excitation signal corresponding to the stopband of the active double-T notch filter, obtaining a filtered magnetic particle signal. The magnetic particle signal is amplified through the low-noise amplifier, and the processed magnetic particle signal is converted into a digital signal through the analog-to-digital converter. An imaging map of the magnetic particle concentration distribution is reconstructed based on the digital signal.

[0026] This application also provides a magnetic particle imaging device based on an active filter. The device includes:

[0027] A signal generating module, which is used to receive the first excitation signal generated by the signal generator. The first excitation signal is amplified by the power amplifier and output to the driving coil to generate a changing magnetic field. The magnetic moment of the magnetic nanoparticles in the driving coil changes under the excitation of the changing magnetic field, generating a magnetic particle signal.

[0028] A signal receiving module, which is used to receive the current signal induced by the receiving coil corresponding to the driving coil. The current signal includes a second excitation signal with the same frequency as the first excitation signal induced by the receiving coil based on the first excitation signal and a magnetic particle signal.

[0029] An imaging module, which is used to process the current signal through the active double-T notch filter to filter out the second excitation signal corresponding to the stopband of the active double-T notch filter, and reconstruct an imaging map of the magnetic particle concentration distribution based on the remaining magnetic particle signal.

[0030] The present application also provides a magnetic particle imaging device based on an active filter. The magnetic particle imaging device based on an active filter is an entity node device, and the magnetic particle imaging device based on an active filter includes: a memory, a processor, and a program of the magnetic particle imaging method based on an active filter that is stored on the memory and can run on the processor. When the program of the magnetic particle imaging method based on an active filter is executed by the processor, the steps of the magnetic particle imaging method based on an active filter as described above can be implemented.

[0031] To achieve the above object, a computer-readable storage medium is also provided. A magnetic particle imaging program based on an active filter is stored on the computer-readable storage medium. When the magnetic particle imaging program based on an active filter is executed by a processor, the steps of any of the above-mentioned magnetic particle imaging methods based on an active filter are implemented.

[0032] The present application provides a magnetic particle imaging method based on an active filter and its related device. A first excitation signal generated by the signal generator is received. The first excitation signal is amplified by the power amplifier and output to the drive coil to generate a changing magnetic field. The magnetic nanoparticles in the drive coil change their magnetic moments under the excitation of the changing magnetic field, generating a magnetic particle signal. A current signal induced by a receiving coil corresponding to the drive coil is received. The current signal includes a second excitation signal having the same frequency as the first excitation signal induced by the receiving coil based on the first excitation signal and a magnetic particle signal. The current signal is processed by the active twin-T notch filter to filter out the second excitation signal corresponding to the stopband of the active twin-T notch filter, and an imaging map of the magnetic particle concentration distribution is reconstructed based on the remaining magnetic particle signal. That is, in the present application, the excitation signal is processed by the active twin-T notch filter. Due to the narrow stopband bandwidth characteristic of the active twin-T notch filter, only the frequency signals within the stopband can be filtered, and the influence on other frequencies is very small. Therefore, the magnetic particle signal can be better restored, the signal-to-noise ratio of imaging is improved, and a better imaging effect is achieved. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 It is a schematic flowchart of the first embodiment of the magnetic particle imaging method based on an active filter of the present application;

[0034] Figure 2 It is a schematic framework diagram of the magnetic particle imaging system based on an active filter involved in the embodiment solution of the present application;

[0035] Figure 3 It is a circuit diagram of the active twin-T notch filter in an embodiment of the magnetic particle imaging method based on an active filter of the present application;

[0036] Figure 4 It is a comparison diagram of the amplitude-frequency characteristics of an active double-T notch filter and a passive double-T notch filter in an embodiment of the magnetic particle imaging method based on an active filter according to the present application;

[0037] Figure 5 It is a comparison diagram of the signal spectrum distributions of an active double-T notch filter and a passive double-T notch filter in an embodiment of the magnetic particle imaging method based on an active filter according to the present application;

[0038] Figure 6 It is a schematic diagram of the device structure of the hardware operating environment involved in the solution of the embodiment of the present application;

[0039] Figure 7 It is a schematic diagram of the functional modules of a preferred embodiment of the magnetic particle imaging device based on an active filter according to the present application. Detailed implementation manners

[0040] It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0041] An embodiment of the present application provides a magnetic particle imaging method based on an active filter. In an embodiment of the magnetic particle imaging method based on an active filter according to the present application, it is applied to a magnetic particle imaging device based on an active filter. Referring to Figure 1 , the method includes:

[0042] Step S10: Receive a first excitation signal generated by the signal generator. The first excitation signal is amplified by the power amplifier and output to the drive coil to generate a changing magnetic field. The magnetic nanoparticles in the drive coil have their magnetic moments changed under the excitation of the changing magnetic field, generating a magnetic particle signal;

[0043] Step S20: Receive a current signal induced by a receiving coil corresponding to the drive coil. The current signal includes a second excitation signal with the same frequency as the first excitation signal induced by the receiving coil based on the first excitation signal and a magnetic particle signal;

[0044] Step S30: Perform signal processing on the current signal through the active double-T notch filter, filter out the second excitation signal corresponding to the stopband of the active double-T notch filter, and reconstruct an imaging map of the magnetic particle concentration distribution based on the retained magnetic particle signal.

[0045] The purpose of this embodiment is to: process the signals of the magnetic particle imaging system through an active double-T notch filter. Due to the narrow stopband bandwidth characteristic of the active double-T notch filter, it can only filter the frequency signals in the stopband and has little influence on the magnetic particle signal, thereby solving the problem of low signal-to-noise ratio in magnetic particle imaging.

[0046] Specifically, in the present application, the magnetic particle imaging system includes a signal generator, a power amplifier, and an active twin-T notch filter. The power amplifier amplifies the excitation signal generated by the signal generator. After the amplified excitation signal is filtered by the stopband of the active twin-T notch filter, the magnetic particle signal is retained, and an imaging map of the magnetic particle concentration distribution is reconstructed. Thus, by processing the excitation signal with the active twin-T notch filter, due to the narrow stopband bandwidth characteristic of the active twin-T notch filter, only the frequency signals within the stopband can be filtered, and the influence on other frequencies is very small. Therefore, the magnetic particle signal can be better restored, the signal-to-noise ratio of imaging is improved, and a better imaging effect is achieved.

[0047] In this embodiment, the specific application scenario is:

[0048] During the magnetic particle imaging process, it is necessary to remove interference signals to ensure the accuracy of the reconstructed magnetic particle concentration distribution map. Currently, the method for removing interference signals is to suppress the excitation signal through a band-stop filter. However, the stopband of a general passive band-stop filter is relatively large. While filtering the excitation signal, it also filters some magnetic particle signals. How to minimize the influence of the filter on the magnetic particle signal is a challenging task.

[0049] For the above reasons, currently, in order to filter the excitation signal, the commonly used methods are the gradient receiving coil and the cancellation method. The cancellation method is to add a signal in the signal receiving chain that has the same frequency and amplitude as the excitation signal but a phase difference of 180 degrees. This method requires accurate phase adjustment to achieve a better effect. The method of the gradient receiving coil is to set the geometric structure of the coil to achieve the filtering effect. This method depends on the reasonable design of the coil and can only be applied to one-dimensional imaging devices. Therefore, there is a problem of poor signal processing effect in the existing magnetic particle imaging, which further results in a low signal-to-noise ratio of imaging.

[0050] As an example, the magnetic particle imaging method based on an active filter can be applied to a magnetic particle imaging system based on an active filter, and the magnetic particle imaging system based on an active filter is applied to a magnetic particle imaging device based on an active filter.

[0051] As an example, the magnetic particle imaging system based on an active filter includes a signal generation subsystem and a signal reception subsystem. The signal generation subsystem includes a signal generator, a power amplifier, and a drive coil. The signal reception subsystem includes an active twin-T notch filter, a receiving coil, a low-noise amplifier, and an analog-to-digital converter.

[0052] As an example, the signal generator is used to generate an excitation signal, which is also the input signal and mainly works by reducing the square wave frequency and superimposing voltages. In the sequential logic circuit, it is also the internal output signal of what is also called a combinational circuit.

[0053] As an example, a power amplifier refers to an amplifier that can produce the maximum power output to drive a certain load (such as a speaker) under given distortion rate conditions.

[0054] As an example, an active twin-T notch filter belongs to notch filters, which are also a type of band-stop filter. The advantage of a notch filter over a general band-stop filter is that it has very good cut-off characteristics and a small stopband. Therefore, it can filter out the excitation signal, and has less impact on the magnetic particle signal than a general band-stop filter, and can better retain the signal generated by magnetic particles and reduce distortion, which is very important for the X-space based reconstruction method.

[0055] As an example, a notch filter is a filter that can rapidly attenuate the input signal at a certain frequency point to achieve the filtering effect of blocking the passage of this frequency signal. Notch filters are specifically used for filtering special frequency signals in circuits and are widely used. For example, in the amplification circuits of weak signals such as artificial seismic signals, electrocardiogram signals, and electroencephalogram signals, notch filters are used to suppress the 50Hz power frequency interference signal of the commercial power supply. In the television image signal processing circuit, notch filters are used to reduce the interference of sound signals. In magnetic particle imaging, we usually need to filter the excitation signal, and the frequency of this excitation signal is usually fixed or has only a small change, which very much conforms to the characteristics of a notch filter. Moreover, the stopband of a notch filter is very narrow, and its impact on the magnetic particle signal is very small. Therefore, notch filters are very suitable for filtering the excitation signal in the signal reception chain of magnetic particle imaging.

[0056] As an example, in an active filter, the frequency range through which the signal can pass is called the passband; conversely, the frequency range in which the signal is greatly attenuated or completely suppressed is called the stopband; the boundary frequency between the passband and the stopband is called the cut-off frequency.

[0057] Among them, a fast decline in the amplitude of the excitation signal indicates good cut-off characteristics. Compared with a general band-stop filter, a notch filter with good cut-off characteristics and a small stopband has a better filtering effect on the excitation signal, and has less impact on the magnetic particle signal than a general band-stop filter, and can better retain the signal generated by magnetic particles and reduce distortion.

[0058] As an example, an active filter-based magnetic particle imaging system is applied in an MPI scanner and can be used for spectral analysis and two-dimensional imaging, where, referring to Figure 2 , Figure 2It is a framework schematic diagram of a magnetic particle imaging system based on an active filter. The signal generator is connected to the power amplifier, the power amplifier is connected to the magnetic field coil, and an active twin-T notch filter is connected to the other end of the magnetic field coil. After the active twin-T notch filter, an ADC (Analog-to-digital converter) is connected.

[0059] As an example, the magnetic field coil includes a drive coil and a receive coil. The drive coil is connected to the power amplifier, and the receive coil is connected to the active twin-T notch filter. Among them, the receive coil uses a gradient receive coil.

[0060] The specific steps are as follows:

[0061] Step S10: Receive the first excitation signal generated by the signal generator. The first excitation signal is amplified by the power amplifier and output to the drive coil to generate a changing magnetic field. The magnetic nanoparticles in the drive coil have their magnetic moments changed under the excitation of the changing magnetic field, generating a magnetic particle signal.

[0062] As an example, the signal generator is a device that generates various signals. As a signal source, it provides a measurement signal with a specific frequency or spectrum and an appropriate amplitude to excite the circuit under test. During the test and adjustment process of electronic circuits, it is often necessary to input a signal that simulates the operation of the circuit, and then a signal generator is needed.

[0063] As an example, the first excitation signal is generated by the signal generator, and the magnetic particle imaging system based on the active filter receives the real-time first excitation signal for scanning and processing the first excitation signal.

[0064] As an example, according to the stopband, cut-off characteristics of the active twin-T notch filter and experiments, it is determined that the filtering effect of the 20 kHz excitation signal is the best. Therefore, the signal generator generates a 20 kHz first excitation signal.

[0065] Step S20: Receive the current signal induced by the receive coil corresponding to the drive coil. The current signal includes a second excitation signal with the same frequency as the first excitation signal induced by the receive coil based on the first excitation signal and the magnetic particle signal.

[0066] As an example, after the first excitation signal is amplified by the power amplifier, a current signal is generated by the action of the magnetic field coil. The current signal includes a second excitation signal with the same frequency as the first excitation signal induced by the receive coil based on the first excitation signal and the magnetic particle signal.

[0067] Among them, the magnetic particle signal, such as the signal of magnetite, is excited by the excitation signal of the magnetic coil, and magnetic particles are emitted in the coil to form a magnetic particle signal.

[0068] As an example, the driving coil works to generate an alternating magnetic field or a strongly varying magnetic field. The magnetic moments of the magnetic nanoparticles in the driving coil change under the excitation of the varying magnetic field, generating a magnetic particle signal. Since the magnetic moments of the magnetic particles of the excitation signal and the magnetic particle signal change, causing a change in the magnetic flux of the magnetic field coil, a current signal will be induced in the receiving coil.

[0069] Step S30: Perform signal processing on the current signal through the active double-T notch filter, filter out the second excitation signal corresponding to the stopband of the active double-T notch filter, and reconstruct an imaging map of the magnetic particle concentration distribution based on the retained magnetic particle signal.

[0070] As an example, compared with the passive notch filter, the active double-T notch filter is formed by using an operational amplifier on the basis of a double-T network and adding appropriate feedback.

[0071] Among them, the passive notch filter is composed of a parallel connection of an RC low-pass filter and an RC high-pass filter. However, this passive double-T network has a small input impedance and a large output impedance, is easily affected by the front and rear stages of the circuit, has a poor cut-off characteristic, and a low Q value (quality factor).

[0072] As an example, the quality factor (Q value) is a basic parameter characterizing the characteristics of a resonant circuit in an electronic circuit. That is, the quality factor or Q factor is an electromagnetic quantity representing the ratio of the energy stored in an energy storage device (such as an inductor, an inductive coil, a capacitor, etc.), a resonant circuit to the energy lost per cycle; the Q value of the reactance element in a series resonant circuit is equal to the ratio of its reactance to its equivalent series resistance; the larger the Q value of the element, the better the selectivity of the circuit or network formed by using this element.

[0073] For removing interference signals, the larger the Q value, the smaller the stopband of the corresponding filter, which can filter a large number of excitation signals, better retain the magnetic particle signal, and improve the signal filtering effect.

[0074] As an example, the magnetic particle imaging system based on an active filter further includes a low-noise amplifier and an analog-to-digital converter. The step of performing signal processing on the current signal through the active double-T notch filter, filtering out the second excitation signal corresponding to the stopband of the active double-T notch filter, and reconstructing an imaging map of the magnetic particle concentration distribution based on the retained magnetic particle signal includes:

[0075] Step S31: Process the current signal through the active bi-T notch filter to filter out the second excitation signal corresponding to the stopband of the active bi-T notch filter, and obtain the filtered magnetic particle signal;

[0076] Step S32: Amplify the magnetic particle signal through the low-noise amplifier, and the processed magnetic particle signal is converted into a digital signal through the analog-to-digital converter;

[0077] Step S33: Reconstruct an imaging map of the magnetic particle concentration distribution based on the digital signal.

[0078] As an example, the stopband refers to the frequency range in which the signal in the active bi-T notch filter is greatly attenuated or completely suppressed, and this frequency range is the stopband of the active bi-T notch filter.

[0079] Usually, in a magnetic particle imaging scanner based on an active filter, the frequency of the excitation signal is 20 kHz, and the frequency of the magnetic particle signal is much higher than that of the excitation signal (for example, the frequency of the magnetic particle signal is 40 kHz, 60 kHz, 100 kHz, etc.). Then, the active bi-T notch filter can filter out the excitation signal in the signal reception chain of the magnetic particle imaging system based on the active filter, with less impact on the magnetic particle signal, and more of the magnetic particle signal is retained, thereby improving the signal-to-noise ratio of the imaging.

[0080] As an example, the active bi-T notch filter filters the current signal induced by the receiving coil. The second excitation signal is greatly reduced, and then the second excitation signal corresponding to the stopband of the active bi-T notch filter will be filtered out to obtain the filtered magnetic particle signal. The filtered signal is amplified to a preset range by the low-noise amplifier and then converted into a digital signal through the ADC, and an imaging map of the magnetic particle concentration distribution is reconstructed based on the digital signal.

[0081] The present application provides a magnetic particle imaging method based on an active filter and related devices. Compared with the low signal-to-noise ratio of the current magnetic particle imaging based on an active filter, in the present application, it is applied to a magnetic particle imaging system based on an active filter. The magnetic particle imaging system based on an active filter includes a signal generator, a power amplifier, and an active twin-T notch filter. The method includes: receiving a first excitation signal generated by the signal generator, amplifying the first excitation signal through the power amplifier, and outputting it to a drive coil to generate a changing magnetic field. The magnetic nanoparticles in the drive coil have their magnetic moments changed under the excitation of the changing magnetic field, generating a magnetic particle signal; receiving a current signal induced by a receiving coil corresponding to the drive coil. The current signal includes a second excitation signal with the same frequency as the first excitation signal induced by the receiving coil based on the first excitation signal and the magnetic particle signal; performing signal processing on the current signal through the active twin-T notch filter, filtering out the second excitation signal corresponding to the stopband of the active twin-T notch filter, and reconstructing an imaging map of the magnetic particle concentration distribution based on the retained magnetic particle signal. That is, in the present application, by processing the excitation signal through an active twin-T notch filter, due to the narrow stopband bandwidth characteristic of the active twin-T notch filter, it can only filter the frequency signals within the stopband and has little influence on other frequencies. Therefore, the magnetic particle signal can be better restored, the signal-to-noise ratio of imaging is improved, and a better imaging effect is achieved.

[0082] Based on the first embodiment of the above magnetic particle imaging method based on an active filter, a second embodiment of the magnetic particle imaging method based on an active filter is proposed.

[0083] The active twin-T notch filter is composed of an RC low-pass filter, an RC high-pass filter, and an operational amplifier feedback circuit.

[0084] As an example, a general passive notch filter is composed of a parallel connection of an RC low-pass filter and an RC high-pass filter. However, this passive twin-T network has a small input impedance and a large output impedance, is easily affected by the front and rear stages of the circuit, has a poor cut-off characteristic, and a low Q value. Although a high-order passive notch filter achieves a good filtering effect and a high Q value, the circuit is complex and the parameter values of the components are relatively special, making it difficult to apply in practice. Usually, the excitation signal in a magnetic particle imaging scanner is around 20 kHz. At this time, the center frequency of the notch filter is relatively high and the bandwidth is relatively large, and the signal of the magnetic particles may be affected and it is not suitable to be directly used. In the research in this article, we use an operational amplifier on the basis of the twin-T network and add appropriate feedback to form an active twin-T notch filter.

[0085] As an example, refer to Figure 3, The circuit diagrams of the RC low-pass filter and the RC high-pass filter include a first resistor R1 and a second resistor R2. The first resistor R1 is connected to the positive pole of the signal source input. The first resistor R1 and the second resistor R2 are connected in series. A first capacitor C1 is connected between the first resistor R1 and the second resistor R2, and the other end of the first capacitor C1 is grounded. A second capacitor C2 is connected in parallel with the first resistor R1. The second capacitor C2 is connected in series with a third resistor R3. The third resistor R3 is connected in parallel with the first capacitor C1, and the other end of the third resistor R3 is grounded. A third capacitor C3 is connected in parallel with the second resistor R2. The third capacitor C3 is connected in series with the second capacitor C2, and the other end of the third capacitor C3 is grounded.

[0086] The double-T network of the common double-T notch filter consists of one resistor and two capacitors (such as Figure 3 the circuit composed of the third resistor R3, the second capacitor C2, and the third capacitor C3 in Figure 3 ), and the other with two resistors and one capacitor forms another T-type filter (such as

[0087] the circuit composed of the first resistor R1, the second resistor R2, and the first capacitor C1 in

[0088] ). Figure 3 , The op-amp feedback circuit includes a first amplifier A1 and a second amplifier A2. The positive power supply terminal of the first amplifier A1 is electrically connected to the output terminals of the second resistor R2 and the third capacitor C3. The negative power supply terminal of the first amplifier A1 is electrically connected to the output terminal of the first amplifier A1. The output terminal of the first amplifier A1 is connected in series with a fourth resistor Ra and a fifth resistor Rb, and the other end of the fifth resistor Rb is grounded. The output terminal of the second amplifier A2 is electrically connected to the output terminals of the first capacitor C1 and the third resistor R3. The negative power supply terminal of the second amplifier A2 is electrically connected to the output terminal of the second amplifier A2. The positive power supply terminal of the second amplifier A2 is electrically connected to the output terminal of the fourth resistor Ra.

[0089] In this embodiment, the vertical arm of the double-T network is connected to the output terminal of the first amplifier A1. The first amplifier A1 feeds back a part of the output signal of the second amplifier A2 to the vertical arm of the double-T network to form a bootstrap, thereby introducing positive feedback. The Q value will increase as the feedback amount increases, making the stopband of the notch filter narrower and the Q value higher.

[0090] When the fifth resistor Rb = 0, that is, there is no positive feedback, the active notch filter becomes a passive notch filter, and Q = 1 / 4. The closer K is to 1, the larger the Q value. By adjusting the voltage division ratio of the fourth resistor Ra and the fifth resistor Rb, the Q value can be effectively adjusted. In actual design, for the convenience of adjusting the voltage division ratio of the fourth resistor Ra and the fifth resistor Rb to achieve the purpose of adjusting the Q value, the fourth resistor Ra and the fifth resistor Rb are replaced with variable resistors, so that the sliding variable resistor can continuously change the Q value.

[0091] Therefore, in the circuit diagram of the active double-T notch filter, a narrow stopband width can be achieved by increasing the Q value. Generally speaking, the Q value should not be too high, because a high Q value is prone to central frequency oscillation and the phase-frequency characteristic is also abnormal. Therefore, a reasonable value of Q is taken, and this reasonable value can be obtained through experiments and is not specifically limited here.

[0092] Based on the first embodiment or the second embodiment of the above-mentioned magnetic particle imaging method based on an active filter, a third embodiment of the magnetic particle imaging method based on an active filter is proposed.

[0093] As an example, the step of processing the current signal by the active double-T notch filter to filter out the second excitation signal corresponding to the stopband of the active double-T notch filter and obtain the filtered magnetic particle signal includes:

[0094] Step S311, obtaining the signal frequency of the first excitation signal;

[0095] Step S312, determining the resistance value and capacitance value in the active double-T notch filter according to the signal frequency;

[0096] Step S313, adjusting the quality factor of the active double-T notch filter based on the resistance value and capacitance value to obtain the magnetic particle signal after the active double-T notch filter processes the current signal corresponding to the highest quality factor value;

[0097] Wherein, the quality factor represents the size of the stopband of the active double-T notch filter.

[0098] As an example, the signal frequency of the first excitation signal generated by the signal generator is usually about 20 kHz. Obtaining the signal frequency of the first excitation signal, according to the signal frequency, the resistance value and capacitance value in the source double-T notch filter can be determined, which are used to adjust the quality factor (i.e., Q value) in the active double-T notch filter. The higher the Q value, the smaller the stopband of the source double-T notch filter. Therefore, it can filter out the excitation signal, and the influence on the magnetic particle signal is smaller than that of a general band-stop filter, and it can better retain the magnetic particle signal and reduce distortion.

[0099] As an example, the frequency characteristics of an active twin-T notch filter can be expressed as:

[0100]

[0101] When , F = 0, then ω 0 is called the resonant frequency of the twin-T notch filter. On both sides of ω 0 , the cut-off characteristics are very good. Therefore, this filter has good filtering ability for signals with a frequency of ω 0 .

[0102] In MPI, the excitation signal is usually about 20 kHz. According to the above formula, we can determine the values of R and C. For convenience, we set C = 10 nF and R = 800 Ω, as Figure 3 shown. Based on the circuit diagram of the active twin-T notch filter, the quality factor Q value can be adjusted by adjusting the parameters of components such as resistors and capacitors.

[0103] Among them,

[0104] The larger the Q value, the smaller the stopband of the active twin-T notch filter. That is to say, the signal of the active twin-T notch filter attenuates less in high-order harmonics. This is because of the narrow stopband bandwidth of the active filter. It only filters the frequency signals within the stopband and has little influence on other frequencies. Therefore, it can better restore the signal of magnetic particles.

[0105] As an example, for the amplitude-frequency characteristic of the filter, first, we used circuit drawing software (such as Multisim14 software) to perform circuit simulation, and the simulation result of the amplitude-frequency characteristic is as Figure 4 shown. Figure 4 is the amplitude-frequency characteristic diagram of the active twin-T notch filter. Among them, Figure 4 the upper line "active twin-T filter" is the active twin-T notch filter, and the lower line "passive twin-T filter" is the passive twin-T notch filter.

[0106] The first difference between the middle value of the descending part of the amplitude-frequency of the active twin-T notch filter and the middle value of the ascending part of the amplitude-frequency of the active twin-T notch filter, and the second difference between the middle value of the descending part of the amplitude-frequency of the passive twin-T notch filter and the middle value of the ascending part of the amplitude-frequency of the passive twin-T notch filter. The first difference is significantly smaller than the second difference.

[0107] The test results show that the center frequency of the active twin-T notch filter is about 19.9 kHz. Obviously, compared with the passive twin-T notch filter, the active twin-T filter has a narrower stopband bandwidth and better cut-off characteristics.

[0108] As an example, in an MPI scanner, actual signal verification is carried out. A passive twin-T notch filter and an active twin-T notch filter are used for comparison. After the MPI scanner acquires the signal, Fourier transform is performed to obtain the frequency spectrum distribution of the signal. The results are as follows Figure 5 shown. Among them, Figure 5 in the amplitude-frequency of the same frequency signal in, the data of the active twin-T notch filter is on the left, and the data of the passive twin-T notch filter is on the right.

[0109] The test results show that the signal using the active twin-T notch filter has less attenuation in high-order harmonics. This is because of the narrow stopband bandwidth of the active twin-T notch filter. It only filters the frequency signals within the stopband and has little impact on other frequencies. Therefore, it can better restore the signal of magnetic particles. Furthermore, it improves the signal-to-noise ratio of magnetic particle imaging and achieves a better imaging effect.

[0110] Based on the above-mentioned embodiment of a magnetic particle imaging method based on an active filter, a fourth embodiment of the magnetic particle imaging method based on an active filter is proposed.

[0111] A magnetic particle imaging system based on an active filter includes a signal generation subsystem and a signal reception subsystem.

[0112] The signal generation subsystem includes a signal generator, a power amplifier, and a drive coil. The signal generation subsystem is used to receive a first excitation signal generated by the signal generator. The first excitation signal is amplified by the power amplifier and output to the drive coil to generate a changing magnetic field. The magnetic nanoparticles in the drive coil change their magnetic moments under the excitation of the changing magnetic field, generating a magnetic particle signal;

[0113] The signal reception subsystem includes an active twin-T notch filter, a receiving coil, a low-noise amplifier, and an analog-to-digital converter. The signal reception subsystem is used to receive the current signal induced by the receiving coil corresponding to the drive coil. The current signal includes a second excitation signal with the same frequency as the first excitation signal induced by the receiving coil based on the first excitation signal and the magnetic particle signal; the current signal is processed by the active twin-T notch filter to filter out the second excitation signal corresponding to the stopband of the active twin-T notch filter, and an imaging map of the magnetic particle concentration distribution is reconstructed based on the retained magnetic particle signal.

[0114] The signal reception subsystem is also used to process the current signal through the active twin-T notch filter to filter out the second excitation signal corresponding to the stopband of the active twin-T notch filter, obtaining the filtered magnetic particle signal; the magnetic particle signal is amplified by the low-noise amplifier, and the processed magnetic particle signal is converted into a digital signal through the analog-to-digital converter; an imaging map of the magnetic particle concentration distribution is reconstructed based on the digital signal.

[0115] Reference Figure 6 , Figure 6 is a schematic diagram of the device structure of the hardware operating environment involved in the embodiment solution of this application.

[0116] As Figure 6 shown, the magnetic particle imaging device based on an active filter may include: a processor 1001, a memory 1005, and a communication bus 1002. The communication bus 1002 is used to implement the connection communication between the processor 1001 and the memory 1005.

[0117] Optionally, the magnetic particle imaging device based on an active filter may further include a user interface, a network interface, a camera, an RF (Radio Frequency) circuit, sensors, a WiFi module, etc. The user interface may include a display screen (Display) and an input sub-module such as a keyboard (Keyboard). Optionally, the user interface may further include a standard wired interface and a wireless interface. The network interface may include a standard wired interface and a wireless interface (such as a WI-FI interface).

[0118] Those skilled in the art can understand that Figure 6 the structure of the magnetic particle imaging device based on an active filter shown in

[0119] does not constitute a limitation on the magnetic particle imaging device based on an active filter, and may include more or fewer components than those shown, or combine certain components, or have different component arrangements. Figure 6 As

[0120] shown, the memory 1005, as a storage medium, may include an operating system, a network communication module, and a magnetic particle imaging program based on an active filter. The operating system is a program for managing and controlling the hardware and software resources of the magnetic particle imaging device based on an active filter, and supports the operation of the magnetic particle imaging program based on an active filter and other software and / or programs. The network communication module is used to implement the communication between the components inside the memory 1005, as well as the communication with other hardware and software in the magnetic particle imaging system based on an active filter. Figure 6 In the magnetic particle imaging device based on an active filter shown in

[0121] the processor 1001 is used to execute the magnetic particle imaging program stored in the memory 1005 to implement the steps of the magnetic particle imaging method based on an active filter described in any one of the above.

[0122] The present application also provides a magnetic particle imaging device based on an active filter. Referring to Figure 7 , the device includes:

[0123] A signal generation module 10, configured to receive a first excitation signal generated by the signal generator. The first excitation signal is amplified by the power amplifier and output to the drive coil to generate a changing magnetic field. The magnetic nanoparticles within the drive coil have their magnetic moments changed under the excitation of the changing magnetic field, generating magnetic particle signals;

[0124] A signal reception module 20, configured to receive the current signal induced by the reception coil corresponding to the drive coil. The current signal includes a second excitation signal having the same frequency as the first excitation signal induced by the reception coil based on the first excitation signal and magnetic particle signals;

[0125] An imaging module 30, configured to perform signal processing on the current signal through the active dual-T notch filter, filter out the excitation signals corresponding to the stopband of the active dual-T notch filter, and reconstruct an imaging map of the magnetic particle concentration distribution based on the retained magnetic particle signals; the active dual-T notch filter is composed of an RC low-pass filter, an RC high-pass filter, and an operational amplifier feedback circuit.

[0126] And / or, the imaging module further includes:

[0127] A filtering sub-module, configured to perform signal processing on the current signal through the active dual-T notch filter, filter out the second excitation signals corresponding to the stopband of the active dual-T notch filter, and obtain filtered magnetic particle signals; the magnetic particle imaging system based on the active filter further includes a low-noise amplifier and an analog-to-digital converter;

[0128] A signal processing sub-module, configured to amplify the magnetic particle signals through the low-noise amplifier, and the processed magnetic particle signals are converted into digital signals through the analog-to-digital converter;

[0129] An imaging sub-module, configured to reconstruct an imaging map of the magnetic particle concentration distribution based on the digital signals.

[0130] And / or, the filtering sub-module further includes:

[0131] An acquisition unit, configured to acquire the signal frequency of the first excitation signal;

[0132] A numerical determination unit, configured to determine the resistance value and capacitance value in the active dual-T notch filter according to the signal frequency;

[0133] A data adjustment unit, configured to adjust the quality factor of the active twin-T notch filter based on the resistance value and the capacitance value, and obtain the magnetic particle signal after the active twin-T notch filter corresponding to the highest quality factor processes the current signal;

[0134] Wherein, the quality factor represents the stopband size of the active twin-T notch filter.

[0135] And / or, the device further includes:

[0136] A passive twin-T network module, for the circuit diagrams of the RC low-pass filter and the RC high-pass filter include a first resistor, a second resistor, and the first resistor is connected to the positive input terminal of the signal source; the first resistor is connected in series with the second resistor, and a first capacitor is connected between the first resistor and the second resistor, and the other end of the first capacitor is grounded; a second capacitor is connected in parallel with the first resistor, the second capacitor is connected in series with a third resistor, the third resistor is connected in parallel with the first capacitor, and the other end of the third resistor is grounded; a third capacitor is connected in parallel with the second resistor, the third capacitor is connected in series with the second capacitor, and the other end of the third capacitor is grounded.

[0137] And / or, the device further includes:

[0138] An operational amplifier feedback circuit module, for the operational amplifier feedback circuit includes a first amplifier and a second amplifier, the positive power supply terminal of the first amplifier is electrically connected to the output terminals of the second resistor and the third capacitor, and the negative power supply terminal of the first amplifier is electrically connected to the output terminal of the first amplifier; the output terminal of the first amplifier is connected in series with a fourth resistor and a fifth resistor, and the other end of the fifth resistor is grounded; the output terminal of the second amplifier is electrically connected to the output terminals of the first capacitor and the third resistor, the negative power supply terminal of the second amplifier is electrically connected to the output terminal of the second amplifier, and the positive power supply terminal of the second amplifier is electrically connected to the output terminal of the fourth resistor.

[0139] The specific implementation manners of the magnetic particle imaging device based on the active filter in this application are basically the same as those of the above-mentioned embodiments of the magnetic particle imaging method based on the active filter, and will not be described in detail here.

[0140] The embodiments of this application provide a computer-readable storage medium, and the computer-readable storage medium stores one or more programs, and the one or more programs can also be executed by one or more processors to be used to implement the steps of the magnetic particle imaging method based on the active filter described in any one of the above.

[0141] The specific implementation manners of the storage medium of this application are basically the same as those of the above-mentioned embodiments of the magnetic particle imaging method based on the active filter, and will not be described in detail here.

[0142] The present application also provides a computer program product, including a computer program, which when executed by a processor implements the steps of the above-mentioned magnetic particle imaging method based on an active filter.

[0143] The specific implementation manner of the computer program product of the present application is basically the same as that of each embodiment of the above-mentioned magnetic particle imaging method based on an active filter, and will not be repeated here.

[0144] It should be noted that in this text, the term "including", "comprising" or any other variant thereof is intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements not only includes those elements, but also includes other elements not explicitly listed, or further includes elements inherent to such process, method, article or device. Without more limitations, an element defined by the statement "including a..." does not exclude the existence of additional identical elements in the process, method, article or device including that element.

[0145] The serial numbers of the above-mentioned embodiments of the present invention are only for description and do not represent the superiority or inferiority of the embodiments.

[0146] Through the description of the above embodiments, those skilled in the art can clearly understand that the above-mentioned embodiment methods can be implemented by means of software plus a hardware platform, or by hardware, but in many cases the former is a better implementation manner. Based on such an understanding, the technical solution of the present invention, in essence, or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product is stored in a storage medium (such as ROM / RAM, magnetic disk, optical disc), and includes several instructions for causing a terminal device (which may be a mobile phone, computer, server, air conditioner, or network device, etc.) to execute the methods described in various embodiments of the present invention.

[0147] The above are only the preferred embodiments of the present invention, and do not limit the patent scope of the present invention accordingly. Any equivalent structure or equivalent process transformation made by using the description of the present invention and the content of the drawings, or directly or indirectly applied to other related technical fields, shall be equally included in the patent protection scope of the present invention.

Claims

1. A magnetic particle imaging method based on an active filter, characterized in that, applied to a magnetic particle imaging system based on an active filter, the magnetic particle imaging system based on an active filter includes a signal generator, a power amplifier, and an active twin-T notch filter, and the method includes: Receiving a first excitation signal generated by the signal generator, the first excitation signal is amplified by the power amplifier and output to a drive coil to generate a changing magnetic field, and magnetic nanoparticles in the drive coil have their magnetic moments changed under the excitation of the changing magnetic field, generating a magnetic particle signal; Receiving a current signal induced by a receiving coil corresponding to the drive coil, the current signal includes a second excitation signal having the same frequency as the first excitation signal induced by the receiving coil based on the first excitation signal and a magnetic particle signal; Performing signal processing on the current signal through the active twin-T notch filter, filtering out the second excitation signal corresponding to the stopband of the active twin-T notch filter, and reconstructing an imaging map of the magnetic particle concentration distribution based on the retained magnetic particle signal.

2. The magnetic particle imaging method based on an active filter according to claim 1, characterized in that, the magnetic particle imaging system based on an active filter further includes a low-noise amplifier and an analog-to-digital converter, the step of performing signal processing on the current signal through the active twin-T notch filter, filtering out the second excitation signal corresponding to the stopband of the active twin-T notch filter, and reconstructing an imaging map of the magnetic particle concentration distribution based on the retained magnetic particle signal includes: Performing signal processing on the current signal through the active twin-T notch filter, filtering out the second excitation signal corresponding to the stopband of the active twin-T notch filter, and obtaining a filtered magnetic particle signal; Amplifying the magnetic particle signal through the low-noise amplifier, and the processed magnetic particle signal is converted into a digital signal through the analog-to-digital converter; Reconstructing an imaging map of the magnetic particle concentration distribution based on the digital signal.

3. The magnetic particle imaging method based on an active filter according to claim 2, characterized in that, the step of performing signal processing on the current signal through the active twin-T notch filter, filtering out the second excitation signal corresponding to the stopband of the active twin-T notch filter, and obtaining a filtered magnetic particle signal includes: Obtaining the signal frequency of the first excitation signal; Determining the resistance value and capacitance value in the active twin-T notch filter according to the signal frequency; Adjusting the quality factor of the active twin-T notch filter based on the resistance value and capacitance value, and obtaining the magnetic particle signal after the current signal is processed by the active twin-T notch filter corresponding to the highest quality factor value; wherein, the quality factor represents the size of the stopband of the active twin-T notch filter.

4. The magnetic particle imaging method based on an active filter according to any one of claims 1-3, characterized in that, the active twin-T notch filter is composed of an RC low-pass filter, an RC high-pass filter, and an operational amplifier feedback circuit.

5. The magnetic particle imaging method based on an active filter according to claim 4, characterized in that, the circuit diagrams of the RC low-pass filter and the RC high-pass filter include a first resistor and a second resistor, the first resistor is connected to the positive power supply; the first resistor is in series with the second resistor, and a first capacitor is connected between the first resistor and the second resistor, and the other end of the first capacitor is grounded; a second capacitor is connected in parallel with the first resistor, the second capacitor is in series with a third resistor, the third resistor is in parallel with the first capacitor, and the other end of the third resistor is grounded; a third capacitor is connected in parallel with the second resistor, the third capacitor is in series with the second capacitor, and the other end of the third capacitor is grounded.

6. The magnetic particle imaging method based on an active filter according to claim 5, characterized in that, the operational amplifier feedback circuit includes a first amplifier and a second amplifier, the positive power supply terminal of the first amplifier is electrically connected to the output terminals of the second resistor and the third capacitor, and the negative power supply terminal of the first amplifier is electrically connected to the output terminal of the first amplifier; the output terminal of the first amplifier is in series with a fourth resistor and a fifth resistor, and the other end of the fifth resistor is grounded; the output terminal of the second amplifier is electrically connected to the output terminals of the first capacitor and the third resistor, the negative power supply terminal of the second amplifier is electrically connected to the output terminal of the second amplifier, and the positive power supply terminal of the second amplifier is electrically connected to the output terminal of the fourth resistor.

7. A magnetic particle imaging system based on an active filter, characterized in that, the system includes a signal generation subsystem and a signal reception subsystem, the signal generation subsystem includes a signal generator, a power amplifier, and a drive coil, the signal generation subsystem is used to receive a first excitation signal generated by the signal generator, the first excitation signal is amplified by the power amplifier and output to the drive coil to generate a changing magnetic field, and the magnetic nanoparticles in the drive coil have their magnetic moments changed under the excitation of the changing magnetic field to generate a magnetic particle signal; the signal reception subsystem includes an active twin-T notch filter, a receiving coil, a low-noise amplifier, and an analog-to-digital converter, the signal reception subsystem is used to receive the current signal induced by the receiving coil corresponding to the drive coil, the current signal includes a second excitation signal with the same frequency as the first excitation signal induced by the receiving coil based on the first excitation signal and the magnetic particle signal; the active twin-T notch filter is used to process the current signal to filter out the second excitation signal corresponding to the stopband of the active twin-T notch filter, and an imaging map of the magnetic particle concentration distribution is reconstructed based on the remaining magnetic particle signal; The signal receiving subsystem is further configured to process the current signal through the active dual-T notch filter, filter out the second excitation signal corresponding to the stopband of the active dual-T notch filter, and obtain a filtered magnetic particle signal; amplify the magnetic particle signal through the low-noise amplifier, and the processed magnetic particle signal is converted into a digital signal through the analog-to-digital converter; reconstruct an imaging map of the magnetic particle concentration distribution based on the digital signal.

8. A magnetic particle imaging device based on an active filter, characterized in that it is applied to a magnetic particle imaging system based on an active filter, and the magnetic particle imaging system based on an active filter includes a signal generator, a power amplifier, and an active dual-T notch filter. The device includes: a signal generating module, configured to receive a first excitation signal generated by the signal generator, the first excitation signal is amplified by the power amplifier and output to a drive coil to generate a changing magnetic field, and magnetic nanoparticles in the drive coil generate a magnetic particle signal under the excitation of the changing magnetic field; a signal receiving module, configured to receive a current signal induced by a receiving coil corresponding to the drive coil, the current signal includes a second excitation signal having the same frequency as the first excitation signal induced by the receiving coil based on the first excitation signal and a magnetic particle signal; an imaging module, configured to process the current signal through the active dual-T notch filter, filter out the second excitation signal corresponding to the stopband of the active dual-T notch filter, and reconstruct an imaging map of the magnetic particle concentration distribution based on the remaining magnetic particle signal.

9. A magnetic particle imaging device based on an active filter, characterized in that the magnetic particle imaging device based on an active filter includes a memory, a processor, and a magnetic particle imaging program based on an active filter stored on the memory and executable on the processor. When the processor executes the magnetic particle imaging program based on an active filter, the steps of the magnetic particle imaging method according to any one of claims 1 to 6 are implemented.

10. A computer-readable storage medium, characterized in that a magnetic particle imaging program based on an active filter is stored on the computer-readable storage medium, and when the magnetic particle imaging program based on an active filter is executed by a processor, the steps of the magnetic particle imaging method according to any one of claims 1 to 6 are implemented.

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