Two-dimensional magnetic particle imaging signal receiving link based on active compensation and acquisition method

Abstract

The application discloses a kind of two-dimensional magnetic particle imaging signal receiving link and acquisition method based on active compensation, comprising: signal generator;Power amplifier, input end is electrically connected with the first output end of signal generator;Capacitor, first end is electrically connected with the output end of power amplifier;Excitation coil, first end is electrically connected with the second end of capacitor, the second end of excitation coil is grounded;Detection coil, second end is grounded;Pre-amplifier, first input end is electrically connected with the first end of detection coil, second input end is electrically connected with the second output end of signal generator;Acquisition card, input end is electrically connected with the output end of pre-amplifier;Central processing unit, input end is electrically connected with the output end of acquisition card, the output end of central processing unit is electrically connected with the input end of signal generator.The application realizes accurate cancellation for feedthrough interference, obtains full harmonic signal containing base frequency component, and improves the sensitivity of equipment.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of biomedical imaging, and particularly relates to a two-dimensional magnetic particle imaging signal receiving link based on active compensation and an acquisition method. BACKGROUND

[0002] Magnetic particle imaging (MPI) is a new medical tomography technology, which images the spatial distribution of magnetic particles by the nonlinear response characteristics of superparamagnetic iron oxide nanoparticles (SPIO) in a changing magnetic field. MPI has high spatial and temporal resolution, high sensitivity, no ionizing radiation hazard, quantitative detection capability, and other advantages, and can be applied to blood vessel imaging, perfusion imaging, tumor detection, magnetic hyperthermia guidance, magnetic drug delivery, and other scenarios, and has wide prospects and development potential.

[0003] In the prior art, in the magnetic particle imaging device, due to the mutual inductance phenomenon of the excitation coil and the detection coil, the fundamental component of the particle signal is affected by the feedthrough interference and cannot be used, resulting in a decrease in particle signal strength and affecting the sensitivity of the imaging device.

[0004] Therefore, it is necessary to improve the above-mentioned defects in the prior art. SUMMARY

[0005] In order to solve the above-mentioned problems in the prior art, the present application provides a two-dimensional magnetic particle imaging signal receiving link based on active compensation and an acquisition method. The technical problem to be solved by the present application is solved by the following technical scheme:

[0006] In a first aspect, the present application provides a two-dimensional magnetic particle imaging signal receiving link based on active compensation, comprising:

[0007] A signal generator comprising a first output end, a second output end and an input end, the signal generator being configured to generate an excitation signal and a cancellation signal, and the excitation signal being output from the first output end of the signal generator and the cancellation signal being output from the second output end of the signal generator;

[0008] A power amplifier comprising an input end and an output end, the input end of the power amplifier being electrically connected to the first output end of the signal generator;

[0009] A capacitor comprising a first end and a second end, the first end of the capacitor being electrically connected to the output end of the power amplifier;

[0010] An excitation coil comprising a first end and a second end, one end of the excitation coil being electrically connected to the second end of the capacitor, and the second end of the excitation coil being grounded;

[0011] The detection coil comprises a first end and a second end, and the second end of the detection coil is grounded; and the excitation coil is nested with the detection coil;

[0012] The preamplifier comprises a first input end, a second input end and an output end, the first input end of the preamplifier is electrically connected with the first end of the detection coil, and the second input end of the preamplifier is electrically connected with the second output end of the signal generator;

[0013] The acquisition card comprises an input end and an output end, and the input end of the acquisition card is electrically connected with the output end of the preamplifier;

[0014] The central processor comprises an input end and an output end, the input end of the central processor is electrically connected with the output end of the acquisition card, and the output end of the central processor is electrically connected with the input end of the signal generator.

[0015] In a second aspect, the present application further provides a two-dimensional magnetic particle imaging signal acquisition method based on active compensation, comprising:

[0016] The signal generator generates an excitation signal and a cancellation signal;

[0017] The excitation signal is transmitted from the first output end of the signal generator to the input end of the power amplifier, and the power amplifier processes the excitation signal;

[0018] The excitation signal processed by the power amplifier is transmitted from the output end of the power amplifier to the first end of the capacitor, and then transmitted from the second end of the capacitor to the first end of the excitation coil; the capacitor and the excitation coil form a resonant network, under the action of the excitation signal, the excitation coil in the resonant network generates a high-frequency alternating magnetic field, which is used to excite a particle signal;

[0019] The feedthrough interference signal processed by the detection coil is transmitted from the first end of the detection coil to the first input end of the preamplifier, and the preamplifier processes the feedthrough interference signal processed by the detection coil;

[0020] The feedthrough interference signal processed by the preamplifier is transmitted from the output end of the preamplifier to the input end of the acquisition card, and then transmitted from the output end of the acquisition card to the input end of the central processor, so as to obtain the amplitude information and the phase information of the feedthrough interference signal, and transmit the amplitude information and the phase information from the output end of the central processor to the input end of the signal generator;

[0021] The signal generator generates a cancellation signal according to the amplitude information and the phase information of the feedthrough interference signal, and the cancellation signal is transmitted from the second output end of the signal generator to the second input end of the preamplifier; the preamplifier differentially processes the feedthrough interference signal and the cancellation signal, so as to realize the cancellation of the feedthrough interference;

[0022] The particle signal is transmitted from the output end of the detection coil to the first input end of the preamplifier, and the preamplifier amplifies the particle signal to obtain an amplified full harmonic particle signal containing a fundamental component.

[0023] The present application has the following advantages:

[0024] (1) The two-dimensional magnetic particle imaging signal receiving link and acquisition method based on active compensation provided by the present application adopts a resonance circuit as a signal transmitting link, which greatly reduces the influence of non-linear amplitude and phase drift caused by feedthrough interference due to high equipment power consumption.

[0025] (2) The two-dimensional magnetic particle imaging signal receiving link and acquisition method based on active compensation provided by the present application uses a three-section gradient detection coil to achieve preliminary attenuation of feedthrough interference up to tens of volts or more, so that it can be processed by subsequent electronic equipment.

[0026] (3) The two-dimensional magnetic particle imaging signal receiving link and acquisition method based on active compensation provided by the present application realizes accurate output of the cancellation signal based on accurate acquisition of feedthrough attenuation phase and amplitude information by the signal acquisition\generation device, completes accurate separation of the feedthrough interference and the particle signal, acquires a full harmonic particle signal containing a fundamental component, and improves the sensitivity of the equipment.

[0027] (4) The two-dimensional magnetic particle imaging signal receiving link and acquisition method based on active compensation provided by the present application acquires a full harmonic particle signal containing a fundamental component based on direct acquisition by the hardware end, and further combines with the X-SPACE algorithm to realize two-dimensional fast imaging.

[0028] The present application will be further described in detail below with reference to the accompanying drawings and embodiments. BRIEF DESCRIPTION OF DRAWINGS

[0029] Figure 1 is a structural schematic diagram of a two-dimensional magnetic particle imaging system based on active compensation provided by an embodiment of the present application;

[0030] Figure 2 is a structural schematic diagram of a two-dimensional magnetic particle imaging signal receiving link based on active compensation provided by an embodiment of the present application;

[0031] Figure 3 is a flowchart of a two-dimensional magnetic particle imaging signal acquisition method based on active compensation provided by an embodiment of the present application;

[0032] Figure 4 is a time-domain waveform diagram of a particle signal acquired by an embodiment of the present application;

[0033] Figure 5 is a frequency spectrum distribution diagram of the collected particle signal provided by an embodiment of the present application;

[0034] Figure 6 is a schematic diagram of a reconstructed image with the fundamental frequency component filtered out provided by an embodiment of the present application;

[0035] Figure 7 is a schematic diagram of a reconstructed image containing the fundamental frequency component provided by an embodiment of the present application. DETAILED DESCRIPTION

[0036] The present application will be further described in conjunction with specific embodiments, but the embodiments of the present application are not limited thereto.

[0037] In the prior art, in 2019, Dennis Pantke of Aachen University of Technology in Germany realized the cancellation of feedthrough interference based on the combination of passive compensation and active compensation; in the passive compensation stage, a three-section excitation coil and a one-section detection coil hardware structure were used to realize the preliminary attenuation of the feedthrough interference; in the active compensation stage, the cancellation signal generated externally was transmitted to the receiving link through an injection transformer to realize the attenuation of the feedthrough interference; but the signal transmitting link in the above research did not adopt the way of resonant circuit, resulting in the problem of serious heat generation due to large power consumption of the device; due to the temperature rise of electrical components, the nonlinear amplitude and phase drift of the feedthrough interference occurred, and it was difficult to accurately obtain the amplitude and phase information in the particle signal detection process, resulting in limited cancellation effect.

[0038] In 2020, Thinh Q. Bui of NIST in the United States used two relatively independent detection coils in the magnetic particle spectrometer (MPS); one of the detection coils was used to detect particle signals, and the other detection coil was connected with a lock-in amplifier, which was used to detect the amplitude and phase changes of the feedthrough interference in real time, and the detected data was transmitted to the signal generating device to generate a cancellation signal to realize the attenuation of the feedthrough interference; but this method uses a lower excitation frequency, which aims to reduce the amplitude of the feedthrough interference so that it will not damage the electronic equipment in the receiving link, but the lower excitation frequency will lead to the decline of the sensitivity of the device, so this method is not suitable for MPI imaging devices.

[0039] Therefore, the application provides a two-dimensional magnetic particle imaging signal receiving link based on active compensation and an acquisition method.

[0040] Please refer to Figure 1 , the application provides a two-dimensional magnetic particle imaging system based on active compensation. Figure 1 is a structural schematic diagram of a two-dimensional magnetic particle imaging system based on active compensation provided by an embodiment of the application, and the two-dimensional magnetic particle imaging device based on active compensation provided by the application comprises a pair of permanent magnets 1, a double-axial Helmholtz drive coil set 2 / 3, a solenoid type excitation coil 4, and a three-section gradient detection coil 5. The pair of permanent magnets 1 is composed of two pieces of NdFeB permanent magnets with opposite polarities and is used to generate a zero magnetic field region. When the magnetic particles are located in the region, the magnetic particles generate signals under the action of an external alternating magnetic field. The drive coil set 2 / 3 is orthogonally placed, and the X\Y axial drive coils are respectively connected with 50Hz\1Hz low-frequency sinusoidal alternating currents with an amplitude of 18 App to generate low-frequency alternating magnetic fields with amplitudes of 18mT and 36mT, so that the zero magnetic field region moves, and the generated imaging field of view is 23mm*23mm. The solenoid type excitation coil 4 is connected with a 25kHz high-frequency sinusoidal alternating current with an amplitude of 9 App to generate an alternating magnetic field for exciting particle signals. The three-section gradient detection coil 5 is used to receive particle signals and realize preliminary attenuation of feedthrough interference.

[0041] It should be noted that Figure 1 the embodiments shown in the drawings only schematically show the positional relationship of the pair of permanent magnets 1, the double-axial Helmholtz drive coil set 2 / 3, the solenoid type excitation coil 4, and the three-section gradient detection coil 5, and do not represent the actual size, wherein the three-section gradient detection coil is entirely sleeved in the solenoid type excitation coil.

[0042] Please refer to Figure 2 , the application provides a two-dimensional magnetic particle imaging signal receiving link based on active compensation and an acquisition method. Figure 2 is a structural schematic diagram of a two-dimensional magnetic particle imaging signal receiving link based on active compensation provided by an embodiment of the application, and the two-dimensional magnetic particle imaging signal receiving link based on active compensation provided by the application comprises:

[0043] The signal generator comprises a first output end, a second output end and an input end, and is used to generate an excitation signal and a cancellation signal. The excitation signal is output by the first output end of the signal generator, and the cancellation signal is output by the second output end of the signal generator.

[0044] The power amplifier comprises an input end and an output end, and the input end of the power amplifier is electrically connected with the first output end of the signal generator.

[0045] The capacitor comprises a first end and a second end, and the first end of the capacitor is electrically connected with the output end of the power amplifier.

[0046] The excitation coil comprises a first end and a second end, one end of the excitation coil is electrically connected with the second end of the capacitor, and the second end of the excitation coil is grounded.

[0047] The detection coil comprises a first end and a second end, and the second end of the detection coil is grounded; the excitation coil and the detection coil are arranged in a nested mode.

[0048] The preamplifier comprises a first input end, a second input end and an output end, the first input end of the preamplifier is electrically connected with the first end of the detection coil, and the second input end of the preamplifier is electrically connected with the second output end of the signal generator.

[0049] The acquisition card comprises an input end and an output end, and the input end of the acquisition card is electrically connected with the output end of the preamplifier.

[0050] The central processing unit (CPU) comprises an input end and an output end, the input end of the central processing unit is electrically connected with the output end of the acquisition card, and the output end of the central processing unit is electrically connected with the input end of the signal generator.

[0051] Specifically, please continue to refer to Figure 2 As shown in the figure, the application provides a two-dimensional magnetic particle imaging signal receiving link based on active compensation, an excitation signal and a cancellation signal are generated by a signal generator (RIGOL, DG4162, China), the excitation signal is amplified by a high-performance power amplifier (AE Techron, 7224, USA), and is transmitted to a resonant network composed of an excitation coil and a resonant capacitor; wherein the excitation coil generates an excitation field of 5.2 mT at 25 kHz; the difference processing of the feedthrough interference detected by the detection coil and the cancellation signal and the amplification of the particle signal are completed by a low-noise amplifier (LNA, Stanford Research Systems, SR560, USA); the amplified signal is digitized by an ADC (ART Technology, USB2872-D, China), the sampling rate is 2MSa / s, and finally, a full-harmonic particle signal containing a fundamental frequency component is obtained.

[0052] It should be noted that the second end of the excitation coil is grounded, which is equivalent to that the second end of the excitation coil is electrically connected with the negative port of the power amplifier.

[0053] It should be further explained that the second end of the detection coil is grounded, which is equivalent to that the second end of the detection coil is electrically connected with the negative port of the preamplifier.

[0054] In an alternative embodiment of the present application, the detection coil is a three-section gradient coil.

[0055] In an alternative embodiment of the present application, it further comprises particle SPIONs, which are located inside the detection coil.

[0056] Based on the same inventive concept, the present application further provides a two-dimensional magnetic particle imaging signal acquisition method based on active compensation, please refer to Figure 3 , Figure 3 is a flow chart of the two-dimensional magnetic particle imaging signal acquisition method based on active compensation provided by the embodiments of the present application, and the method comprises:

[0057] S101, the signal generator generates an excitation signal and a cancellation signal;

[0058] S102, the excitation signal is transmitted from the first output end of the signal generator to the input end of the power amplifier, and the power amplifier processes the excitation signal;

[0059] S103, the excitation signal processed by the power amplifier is transmitted from the output end of the power amplifier to the first end of the capacitor, and then transmitted from the second end of the capacitor to the first end of the excitation coil; the capacitor and the excitation coil form a resonant network, under the action of the excitation signal, the excitation coil in the resonant network generates a high-frequency alternating magnetic field, which is used to excite particle signals;

[0060] S104, the feedthrough interference signal processed by the detection coil is transmitted from the first end of the detection coil to the first input end of the preamplifier, and the preamplifier processes the feedthrough interference signal processed by the detection coil;

[0061] S105, the feedthrough interference signal processed by the preamplifier is transmitted from the output end of the preamplifier to the input end of the acquisition card, and then transmitted from the output end of the acquisition card to the input end of the central processor, so as to obtain the amplitude information and the phase information of the feedthrough interference signal, and then transmitted from the output end of the central processor to the input end of the signal generator;

[0062] S106, the signal generator generates a cancellation signal according to the amplitude information and the phase information of the feedthrough interference signal, and the cancellation signal is transmitted from the second output end of the signal generator to the second input end of the preamplifier; the preamplifier differentially processes the feedthrough interference signal and the cancellation signal, so as to realize the cancellation of the feedthrough interference;

[0063] S107, introduce particles, obtain particle signals, the particle signals are transmitted from the output end of the detection coil to the first input end of the preamplifier, the preamplifier amplifies the particle signals to obtain amplified full harmonic particle signals containing the fundamental component.

[0064] Specifically, in the embodiment, when no particles are introduced and the cancellation signal received by the second input end of the preamplifier is zero, the feedthrough interference signal of the excitation coil is obtained and processed by the preamplifier to obtain the amplitude information and phase information of the feedthrough interference signal, and is transmitted to the signal generator and then to the second input end of the preamplifier for real-time elimination of the feedthrough interference signal; when the particles are introduced, the particles are excited to generate particle signals under the action of the high-frequency alternating magnetic field generated by the excitation coil, and on the basis of real-time elimination of the interference signal, the full harmonic particle signals containing the fundamental component are obtained by amplification through the preamplifier, and the sensitivity of the device is improved.

[0065] In an optional embodiment of the present application, when no particles are introduced into the device, the expression of the signal processed by the detection coil is:

[0066] U D = U E + U N ;

[0067] Wherein, U N is the inherent noise of the system, and U E is the feedthrough interference signal.

[0068] In an optional embodiment of the present application, when the cancellation signal received by the second input end of the preamplifier is zero and no particles are introduced into the device, the expression of the signal U T1 processed by the preamplifier is:

[0069]

[0070] Wherein, alpha is the gain of the preamplifier, U N1 is the inherent noise of the system when the signal is not amplified;

[0071] When alpha = 1, the signal is digitized by the ADC to obtain the amplitude information and phase information of the feedthrough interference signal U E .

[0072] In an optional embodiment of the present application, when the cancellation signal received by the second input end of the preamplifier is not zero and no particles are introduced into the receiving link, the expression of the signal processed by the preamplifier is:

[0073]

[0074] Wherein, α1 is the amplification of the preamplifier of this stage, α = 1;

[0075] Because the device has low power consumption and short acquisition time (within 10s), the nonlinear drift of the amplitude information and the phase information of the feedthrough interference signal can be ignored, and the signal is converted, and the expression of the converted signal is as follows:

[0076]

[0077]

[0078] Wherein, is the offset signal U c .

[0079] In an alternative embodiment of the present application, the particle is moved into the receiving link, α = 1000, and the signal for imaging is generated , and the expression of the signal is as follows:

[0080]

[0081] Wherein, α2 is the amplification of the preamplifier of this stage; U P is the full harmonic particle signal containing the fundamental frequency component, and U N2 is the amplified system inherent noise.

[0082] In an alternative embodiment of the present application, in order to verify the feasibility of the active compensation based on the device sensitivity proposed in the present application, relevant experiments are carried out. The particle used in the experiment is a 50mm diameter The concentration used is 25mg / ml, and the volume is 6.28ul; the final acquired particle signal time domain waveform is as shown in Figure 4 The particle signal spectrum distribution is as shown in Figure 5 , Figure 4 is a time domain waveform diagram of the acquired particle signal provided by the embodiment of the present application, Figure 5 is a frequency spectrum distribution diagram of the acquired particle signal provided by the embodiment of the present application, the present application realizes accurate separation of the feedthrough interference and the particle signal, and acquires the full harmonic particle signal containing the fundamental frequency component. The acquired signal is reconstructed by the X-SPACE algorithm, and further comparison is made between the images reconstructed by the particle signals containing the fundamental frequency component and not containing the fundamental frequency component, as shown in Figure 6 and Figure 7 , Figure 6 is a schematic diagram of the reconstructed image of the filtered fundamental frequency component provided by the embodiment of the present application,Figure 7 is a schematic diagram of a reconstructed image containing a fundamental frequency component provided by an embodiment of the present application; and Figure 6 and Figure 7 It can be seen that the pixel intensity of the image reconstructed from the particle signal containing the fundamental frequency component is obviously improved, i.e. it is verified that the method can improve the sensitivity of the device.

[0083] It should be noted that the relational terms herein such as first and second and the like are used solely to distinguish one from another entity or action, without necessarily requiring or implying any actual relationship or order between such entities or actions. Moreover, the terms "comprises", "comprising", or any other variations thereof, are intended to cover a non-exclusive inclusion, such that a process or method that comprises a list of elements does not include only those elements but can also include other elements not expressly listed or inherent to such process or method. Elements denoted by the phrase "comprising a" does not exclude the presence of additional identical elements in the process or method comprising the element. The terms "connected" or "coupled" or similar terms are not limited to a direct connection or coupling but also include an indirect connection or coupling such as through an intermediary. The terms "upper", "lower", "left", "right", and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, which are merely for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application.

[0084] In the description of the present specification, the description referring to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" and the like means that the specific feature or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the present application. The illustrative description of the above terms in the present specification does not necessarily refer to the same embodiment or example. Moreover, the specific feature or characteristic described can be combined in any suitable manner in one or more embodiments or examples. In addition, those skilled in the art can combine and integrate different embodiments or examples described in the present specification.

[0085] The above is a further detailed description of the present application in combination with specific preferred embodiments, and the specific implementation of the present application cannot be limited to these descriptions. For those skilled in the art, without departing from the concept of the present application, a number of simple deductions or substitutions can be made, which should be considered as falling within the scope of protection of the present application.

Claims

1. An active-compensation-based two-dimensional magnetic particle imaging signal reception chain, characterized by, The application relates to a signal processing device for a nuclear magnetic resonance (NMR) instrument. The device comprises a signal generator, a power amplifier, a capacitor, an excitation coil, a detection coil, a preamplifier, a collection card and a central processing unit. The signal generator comprises a first output end, a second output end and an input end, and is used for generating an excitation signal and a cancellation signal, wherein the excitation signal is output from the first output end of the signal generator, and the cancellation signal is output from the second output end of the signal generator. The power amplifier comprises an input end and an output end, and the input end of the power amplifier is electrically connected with the first output end of the signal generator. The capacitor comprises a first end and a second end, and the first end of the capacitor is electrically connected with the output end of the power amplifier. The excitation coil comprises a first end and a second end, one end of the excitation coil is electrically connected with the second end of the capacitor, and the second end of the excitation coil is grounded. The detection coil comprises a first end and a second end, and the second end of the detection coil is grounded. The excitation coil and the detection coil are nested. The feedthrough interference signal processed by the detection coil is transmitted from the first end of the detection coil to the first input end of the preamplifier.

2. The active compensation based two-dimensional magnetic particle imaging signal reception chain of claim 1, wherein, The preamplifier is used for processing the feedthrough interference signal processed by the detection coil.

3. The active compensation based two-dimensional magnetic particle imaging signal reception chain of claim 2, wherein, The preamplifier comprises a first input end, a second input end and an output end, the first input end of the preamplifier is electrically connected with the first end of the detection coil, the second input end of the preamplifier is electrically connected with the second output end of the signal generator, and the preamplifier is used for differentially processing the feedthrough interference signal and the cancellation signal to realize the cancellation of the feedthrough interference. The collection card comprises an input end and an output end, and the input end of the collection card is electrically connected with the output end of the preamplifier.

4. A method for active-compensation-based two-dimensional magnetic particle imaging signal acquisition, characterized by, The central processing unit comprises an input end and an output end, the input end of the central processing unit is electrically connected with the output end of the collection card, and the output end of the central processing unit is electrically connected with the input end of the signal generator. The detection coil is a three-section gradient coil. The device further comprises a particle located in the detection coil. The signal generator generates the excitation signal and the cancellation signal. The excitation signal is transmitted from the first output end of the signal generator to the input end of the power amplifier, and the power amplifier processes the excitation signal. The excitation signal processed by the power amplifier is transmitted from the output end of the power amplifier to the first end of the capacitor, and then is transmitted from the second end of the capacitor to the first end of the excitation coil. The capacitor and the excitation coil form a resonance network, and the excitation coil in the resonance network generates a high-frequency alternating magnetic field under the action of the excitation signal, which is used for exciting a particle signal. The feedthrough interference signal processed by the detection coil is transmitted from the first end of the detection coil to the first input end of the preamplifier, and the preamplifier processes the feedthrough interference signal processed by the detection coil. The feedthrough interference signal processed by the preamplifier is transmitted from the output end of the preamplifier to the input end of the collection card, and then is transmitted from the output end of the collection card to the input end of the central processing unit, so that the amplitude information and the phase information of the feedthrough interference signal are obtained, and the amplitude information and the phase information are transmitted from the output end of the central processing unit to the input end of the signal generator. The signal generator generates a cancellation signal according to the amplitude information and the phase information of the feedthrough interference signal, and the cancellation signal is transmitted by a second output end of the signal generator to a second input end of the preamplifier; the preamplifier differentially processes the feedthrough interference signal and the cancellation signal, so as to realize cancellation of the feedthrough interference; The particle is introduced, and a particle signal is obtained, the particle signal being transmitted by an output end of the detection coil to a first input end of the preamplifier, and the preamplifier amplifies the particle signal to obtain an amplified full-harmonic particle signal containing a fundamental frequency component.

5. The active-compensation-based two-dimensional magnetic particle imaging signal acquisition method according to claim 4, characterized in that, When the particle does not move into the device, an expression of the signal processed by the detection coil is: ； wherein is the noise of the system, is the feed-through interference signal.

6. The active-compensation-based two-dimensional magnetic particle imaging signal acquisition method of claim 4, characterized by, When the second input end of the preamplifier receives a cancellation signal of zero, and the particle does not move into the device, the signal processed through the preamplifier The expression is: ； wherein is the gain of the preamplifier, Snoise is the system inherent noise when the signal is amplified When the signal is digitized by the ADC, the amplitude information and phase information of the feedthrough interference signal are obtained.

7. The active-compensation-based two-dimensional magnetic particle imaging signal acquisition method according to claim 4, characterized in that, When the second input end of the preamplifier receives a cancellation signal that is not zero, and a particle does not move into the device, the signal processed by the preamplifier The expression is: ； wherein the amplification factor of the preamplifier for this stage, , the signal is the inherent noise of the system when amplified, is the feed-through interference signal; signal transformed signal The expression of the transformed signal is ； ； wherein to cancel the signal .

8. The active-compensation-based two-dimensional magnetic particle imaging signal acquisition method according to claim 4, characterized by, moving the particles into the device, amplifying the particle signal, generating a signal for imaging whose expression is: ； wherein amplification of the pre-stage amplifier at this stage; for the full harmonic particle signal including the fundamental component, for the amplified system inherent noise.

Images