CN113625208B - Three-dimensional magnetic particle imaging system and method based on multi-channel excitation and detection - Google Patents

Abstract

The invention belongs to the technical field of biomedical imaging, and particularly relates to a three-dimensional magnetic particle imaging system and method based on multi-channel excitation and detection, aiming at solving the problems of low imaging speed and low imaging precision caused by heating of an electromagnetic coil in the existing magnetic particle imaging technology. The invention comprises the following steps: a multi-channel excitation coil group for exciting the magnetic particles in different directions; a multi-channel detection coil group for detecting response voltage signals of the magnetic particles at different spatial positions and different angles; an AC power supply set for supplying power to the multi-channel exciting coil set; a channel control unit for switching the exciting coils in different directions in the exciting coil group and exciting the magnetic particles in different directions; the signal conditioning unit is used for amplifying and filtering the response voltage signal detected by the multi-channel detection coil group; and the image reconstruction unit is used for carrying out digital signal processing and three-dimensional magnetic particle image reconstruction according to the amplified and filtered response voltage signal. The magnetic particle imaging method is high in magnetic particle imaging speed and high in accuracy.

Description

Three-dimensional magnetic particle imaging system and method based on multi-channel excitation and detection

technical field

The invention belongs to the technical field of biomedical imaging, and particularly relates to a three-dimensional magnetic particle imaging system and method based on multi-channel excitation and detection.

Background technique

Magnetic particles are nano-sized particles with superparamagnetic properties. In recent years, they have been widely studied and applied as a new type of medical imaging tracer in clinical problems such as tumor detection, magnetic particle hyperthermia, and targeted drug delivery.

Traditional magnetic particle imaging methods require controlled gradient magnetic fields with high field strength to encode the entire imaging field of view. For three-dimensional imaging, the encoding process will be very long, which affects the real-time performance of imaging. In addition, if the electromagnetic coil continues to work for too long, it will also cause the coil to heat up, causing measurement errors, which in turn affects the imaging accuracy.

In general, there is also an urgent need in the art for a three-dimensional magnetic particle imaging system and method that can achieve faster imaging speed and can take into account the imaging accuracy.

SUMMARY OF THE INVENTION

In order to solve the above problems in the prior art, that is, the imaging speed of the existing magnetic particle imaging technology is slow, and the heating of the electromagnetic coil leads to the low imaging accuracy, the present invention provides a three-dimensional magnetic particle imaging system based on multi-channel excitation and detection , the three-dimensional magnetic particle imaging system includes a multi-channel excitation coil group, a multi-channel detection coil group, an AC power supply group, a channel control unit, a signal conditioning unit and an image reconstruction unit;

The multi-channel excitation coil group includes a plurality of excitation electromagnetic coils with different excitation directions, which are used to excite magnetic particles in different directions;

The multi-channel detection coil group includes a plurality of detection coil arrays, and each detection coil array in the plurality of detection coil arrays includes a plurality of detection electromagnetic coils for detecting the response voltage signals of the magnetic particles at different spatial positions and different angles ;

the AC power supply group for supplying power to the multi-channel excitation coil group;

The channel control unit is used to switch the excitation coils in different directions in the excitation coil group to excite the magnetic particles in different directions;

The signal conditioning unit is used for amplifying and filtering the response voltage signal detected by the multi-channel detection coil group;

The image reconstruction unit is used for digital signal processing and three-dimensional magnetic particle image reconstruction according to the amplified and filtered response voltage signal.

In some preferred embodiments, the AC power pack includes a multi-channel signal generator and a power amplifier;

The multi-channel signal generator is used to generate the current waveform required by the energized coil group; the current waveform is one of a sine wave, a triangular wave, and a pulsed square wave;

The power amplifier is used to amplify the current waveform generated by the multi-channel signal generator to a set size, and supply power to the multi-channel excitation coil group based on the amplified current waveform.

In some preferred embodiments, the three-dimensional magnetic particle imaging system further includes a display unit;

The display unit is configured to display the three-dimensional magnetic particle image reconstructed by the image reconstruction unit.

In some preferred embodiments, the excitation electromagnetic coils of the multi-channel excitation coil group surround the imaging field of view of the three-dimensional magnetic particle imaging system;

Taking the center of the imaging field of view as the origin of the three-dimensional coordinate system, the excitation electromagnetic coils of the multi-channel excitation coil group are respectively placed in the negative direction of the z-axis, the positive direction of the z-axis, and the positive direction of the x-axis of the three-dimensional coordinate system. and the negative direction of the x-axis; the direction is the direction of the main magnetic field generated by the excitation coil, and the object to be imaged enters the imaging field of view along the y-axis direction.

In some preferred embodiments, the detection coil arrays of the multi-channel detection coil set are placed in a one-to-one correspondence with the excitation electromagnetic coils of the multi-channel excitation coil set;

Each of the detection coil arrays is placed on one side of the corresponding excitation electromagnetic coil close to the imaging field of view, and is used to detect response voltage signals generated by magnetic particles at different spatial positions and multiple angles.

In some preferred embodiments, for the plurality of excitation electromagnetic coils with different excitation directions, at a certain moment, only one excitation electromagnetic coil generates an excitation magnetic field;

When any excitation electromagnetic coil generates an excitation magnetic field, all detection coil arrays simultaneously detect the magnetization response voltage signal generated by the magnetic particles, and the detection coil array in the same direction as the excitation magnetic field is used to detect the magnetization response voltage in the direction of the main magnetic flux generated by the magnetic particles. Signal, the detection coil array perpendicular to the excitation magnetic field is used to detect the magnetization response voltage signal in the direction of the leakage flux generated by the magnetic particles.

In another aspect of the present invention, a three-dimensional magnetic particle imaging method based on multi-channel excitation and detection is proposed. Based on the above-mentioned three-dimensional magnetic particle imaging system based on multi-channel excitation and detection, the three-dimensional magnetic particle imaging method includes:

Step S10, sequentially inputting high-frequency pulse currents to different excitation electromagnetic coils, generating a pulsed magnetic field in a specific direction in the imaging field of view of the three-dimensional magnetic particle imaging system, and exciting the magnetic particles to generate magnetization response voltage signals in different directions;

Step S20, for each excitation electromagnetic coil, use the detection coil array parallel to the excitation electromagnetic coil to detect the magnetization response voltage signal in the direction of the main magnetic flux generated by the magnetic particles, and use the detection coil array perpendicular to the excitation electromagnetic coil to detect. The magnetization response voltage signal in the direction of the leakage flux generated by the magnetic particles;

Step S30, filtering the DC component in the detected response voltage signal through digital filtering technology, and performing fast Fourier transform on the detected signal to obtain a frequency spectrum sequence of the response voltage signal;

Step S40, construct a measurement matrix of multi-channel excitation electromagnetic coils and detection coils, and calculate the spatial distribution of magnetic particle concentration in combination with the frequency spectrum sequence of the response voltage signal, so as to realize three-dimensional magnetic particle image reconstruction.

In some preferred embodiments, the waveform of the high-frequency pulse current is a pulsed square wave with a narrow pulse width.

In some preferred embodiments, the multi-channel excitation electromagnetic coil and the measurement matrix of the detection coil are constructed as follows:

Step S411, dividing the imaging field of view of the three-dimensional magnetic particle imaging system into n reconstruction units based on the preset three-dimensional magnetic particle reconstruction image resolution;

Step S412, put the magnetic particle sample of the object to be imaged into the imaging field of view of the three-dimensional magnetic particle imaging system, and traverse the n reconstruction units: for each reconstruction unit, through the above-mentioned multi-channel excitation and detection-based three-dimensional magnetic particle The corresponding method of steps S10 to S30 of the imaging method obtains a set of spectrum sequences; the set of spectrum sequences constitutes a one-dimensional vector with a length of m;

Step S413: Combine the n groups of spectral sequences corresponding to the n reconstruction units to obtain the measurement matrix of the multi-channel excitation electromagnetic coil and the detection coil; the first column of the measurement matrix is the first group of spectral sequences, and the nth column is the first group of spectral sequences. The nth group of spectrum sequences, the size of the measurement matrix is m rows and n columns.

In some preferred embodiments, the three-dimensional magnetic particle image reconstruction method is:

Step S421, establishing a three-dimensional magnetic particle image reconstruction equation:

F=AC

Among them, A is the measurement matrix of the multi-channel excitation electromagnetic coil and detection coil, F is the spectrum sequence detected by the multi-channel detection coil group, and C is the three-dimensional magnetic particle reconstruction image;

Step S422 , solve the three-dimensional magnetic particle reconstruction image C according to the image reconstruction equation, so as to realize the three-dimensional magnetic particle image reconstruction.

Beneficial effects of the present invention:

The present invention is based on a multi-channel excitation and detection three-dimensional magnetic particle imaging system. The channel control unit controls the excitation electromagnetic coils in different excitation directions to excite the magnetic particles in different directions respectively, and detects the response generated by each excitation electromagnetic coil through the detection coil. Voltage signal, based on the response voltage signal for 3D magnetic particle image reconstruction, eliminating the need for traditional magnetic particle imaging methods to control the gradient magnetic field with high field strength to spatially encode the entire imaging field of view, and avoiding the electromagnetic coil heating and resulting in low imaging accuracy The problem of magnetic particle imaging is fast and high precision.

Description of drawings

Other features, objects and advantages of the present application will become more apparent by reading the detailed description of non-limiting embodiments made with reference to the following drawings:

1 is a schematic diagram of a multi-channel excitation coil assembly and a multi-channel detection coil assembly according to an embodiment of a three-dimensional magnetic particle imaging system based on multi-channel excitation and detection of the present invention;

FIG. 2 is a schematic flowchart of the three-dimensional magnetic particle imaging method based on multi-channel excitation and detection of the present invention.

Detailed ways

The present application will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the related invention, but not to limit the invention. In addition, it should be noted that, for the convenience of description, only the parts related to the related invention are shown in the drawings.

It should be noted that the embodiments in the present application and the features of the embodiments may be combined with each other in the case of no conflict. The present application will be described in detail below with reference to the accompanying drawings and in conjunction with the embodiments.

A three-dimensional magnetic particle imaging system based on multi-channel excitation and detection of the present invention, the three-dimensional magnetic particle imaging system includes a multi-channel excitation coil group, a multi-channel detection coil group, an AC power supply group, a channel control unit, a signal conditioning unit and an image rebuild unit;

The multi-channel excitation coil group includes a plurality of excitation electromagnetic coils with different excitation directions, which are used to excite magnetic particles in different directions;

The multi-channel detection coil group includes a plurality of detection coil arrays, and each detection coil array in the plurality of detection coil arrays includes a plurality of detection electromagnetic coils for detecting the response voltage signals of the magnetic particles at different spatial positions and different angles ;

the AC power supply group for supplying power to the multi-channel excitation coil group;

The channel control unit is used to switch the excitation coils in different directions in the excitation coil group to excite the magnetic particles in different directions;

The signal conditioning unit is used for amplifying and filtering the response voltage signal detected by the multi-channel detection coil group;

The image reconstruction unit is used for digital signal processing and three-dimensional magnetic particle image reconstruction according to the amplified and filtered response voltage signal.

In order to more clearly describe the three-dimensional magnetic particle imaging system based on multi-channel excitation and detection of the present invention, each module in the embodiment of the present invention will be described in detail below with reference to FIG. 1 .

The three-dimensional magnetic particle imaging system based on multi-channel excitation and detection according to the first embodiment of the present invention includes a multi-channel excitation coil group, a multi-channel detection coil group, an AC power supply group, a channel control unit, a signal conditioning unit and an image reconstruction unit. The modules are described in detail as follows:

As shown in FIG. 1, it is a schematic diagram of a multi-channel excitation coil group and a multi-channel detection coil group according to an embodiment of a three-dimensional magnetic particle imaging system based on multi-channel excitation and detection of the present invention, including: excitation coil groups 1, 2, 3 , 4. Detection coil sets 5, 6, 7, 8 and imaging field of view 9 (FOV, Field Of View).

The multi-channel excitation coil set includes a plurality of excitation electromagnetic coils with different excitation directions, and is used for excitation of magnetic particles in different directions.

In the embodiment shown in FIG. 1, the multi-channel excitation coil includes a first excitation coil 1, a second excitation coil 2, a third excitation coil 3 and a fourth excitation coil 4; the direction of the main magnetic field generated by the first excitation coil 1 is The z-axis is negative, the direction of the main magnetic field generated by the second excitation coil 2 is the positive z-axis, the direction of the main magnetic field generated by the third excitation coil 3 is the positive direction of the x-axis, and the direction of the main magnetic field generated by the fourth excitation coil 4 is the x-axis negative.

The imaging field of view of the excitation electromagnetic coil of the multi-channel excitation coil group surrounding the 3D magnetic particle imaging system:

Taking the center of the imaging field of view as the origin of the three-dimensional coordinate system, the excitation electromagnetic coils of the multi-channel excitation coil group are respectively placed in the negative z-axis direction, the positive direction of the z-axis, the positive direction of the x-axis and the negative direction of the x-axis of the three-dimensional coordinate system. The direction is the direction of the main magnetic field generated by the excitation coil, and the object to be imaged can enter the imaging field of view FOV along the y-axis direction.

The multi-channel detection coil set includes a plurality of detection coil arrays, and each detection coil array in the plurality of detection coil arrays includes a plurality of detection electromagnetic coils for detecting response voltage signals of magnetic particles at different spatial positions and different angles.

In the embodiment shown in FIG. 1, the multi-channel detection coil group includes a first coil array 5, a second coil array 6, a third coil array 7 and a fourth coil array 8; each coil array is composed of several small electromagnetic It is composed of coils, which are used to detect the response signals generated by magnetic particles at different spatial positions and multiple angles.

The detection coil arrays of the multi-channel detection coil group are placed in a one-to-one correspondence with the excitation electromagnetic coils of the multi-channel excitation coil group:

Each of the detection coil arrays is placed on one side of the corresponding excitation electromagnetic coil close to the imaging field of view, and is used to detect response voltage signals generated by magnetic particles at different spatial positions and multiple angles.

The AC power pack includes a multi-channel signal generator and power amplifier for powering the multi-channel excitation coil pack:

The multi-channel signal generator is used to generate the current waveform required by the energized coil group. The current waveform is one of sine wave, triangle wave and pulse square wave.

The power amplifier is used to amplify the current waveform generated by the multi-channel signal generator to a set size, and supply power to the multi-channel excitation coil group based on the amplified current waveform.

The channel control unit is used to switch the excitation coils in different directions in the excitation coil group to excite the magnetic particles in different directions.

The signal conditioning unit is used for amplifying and filtering the response voltage signal detected by the multi-channel detection coil group.

The image reconstruction unit is used for digital signal processing and three-dimensional magnetic particle image reconstruction according to the amplified and filtered response voltage signal.

The three-dimensional magnetic particle imaging system further includes a display unit for displaying the three-dimensional magnetic particle image reconstructed by the image reconstruction unit.

For multiple excitation electromagnetic coils with different excitation directions, at a certain moment, only one excitation electromagnetic coil generates an excitation magnetic field:

When any excitation electromagnetic coil generates an excitation magnetic field, all detection coil arrays simultaneously detect the magnetization response voltage signal generated by the magnetic particles, and the detection coil array in the same direction as the excitation magnetic field is used to detect the magnetization response voltage in the direction of the main magnetic flux generated by the magnetic particles. Signal, the detection coil array perpendicular to the excitation magnetic field is used to detect the magnetization response voltage signal in the direction of the leakage flux generated by the magnetic particles.

In the embodiment shown in Figure 1, at a certain time, only one excitation electromagnetic coil is controlled to generate an excitation magnetic field, and all detection coil arrays detect the magnetization response signals generated by magnetic particles at the same time, and the detection coil arrays in the same direction as the excitation magnetic field use For detecting the magnetization response signal in the direction of the main magnetic flux generated by the magnetic particles, the detection coil array perpendicular to the excitation magnetic field is used for detecting the magnetization response signal in the direction of the leakage magnetic flux generated by the magnetic particle. Specifically, when the excitation electromagnetic coil 1 is controlled to excite the magnetic particles in the FOV, the excitation electromagnetic coils 2, 3, and 4 stop working, and the detection coil arrays 5 and 6 detect the magnetization response signals in the main magnetic flux direction generated by the magnetic particles. , the detection coil arrays 7 and 8 detect the magnetization response signal in the direction of the leakage magnetic flux generated by the magnetic particles; after that, the excitation electromagnetic coil 2 is switched to excite the magnetic particles in the FOV, the excitation electromagnetic coils 1, 3 and 4 stop working, and the detection coil The arrays 7 and 8 detect the magnetization response signals in the direction of the main magnetic flux generated by the magnetic particles, and the detection coil arrays 5 and 6 detect the magnetization response signals in the direction of the leakage flux generated by the magnetic particles; then the excitation electromagnetic coil 3 and the excitation electromagnetic coil 4 are switched in turn. For excitation, the working principle of the detection coil is the same as above.

The three-dimensional magnetic particle imaging method based on multi-channel excitation and detection according to the second embodiment of the present invention is based on the above-mentioned three-dimensional magnetic particle imaging system based on multi-channel excitation and detection, as shown in FIG. 2 , the three-dimensional magnetic particle imaging method includes:

Step S10, sequentially inputting high-frequency pulse currents to different excitation electromagnetic coils, generating a pulsed magnetic field in a specific direction in the imaging field of view of the three-dimensional magnetic particle imaging system, and exciting the magnetic particles to generate magnetization response voltage signals in different directions;

Step S20, for each excitation electromagnetic coil, use the detection coil array parallel to the excitation electromagnetic coil to detect the magnetization response voltage signal in the direction of the main magnetic flux generated by the magnetic particles, and use the detection coil array perpendicular to the excitation electromagnetic coil to detect. The magnetization response voltage signal in the direction of the leakage flux generated by the magnetic particles;

Step S30, filtering the DC component in the detected response voltage signal through digital filtering technology, and performing fast Fourier transform on the detected signal to obtain a frequency spectrum sequence of the response voltage signal;

Step S40, construct a measurement matrix of multi-channel excitation electromagnetic coils and detection coils, and calculate the spatial distribution of magnetic particle concentration in combination with the frequency spectrum sequence of the response voltage signal, so as to realize three-dimensional magnetic particle image reconstruction.

Combined with the composition of the multi-channel excitation coil set and the multi-channel detection coil set in FIG. 1, the flow of the three-dimensional magnetic particle imaging method based on multi-channel excitation and detection shown in FIG. 2 is described in detail:

Input high-frequency pulse currents to different excitation coils in turn to excite the magnetic particles to generate magnetization response signals in different directions: use AC power to sequentially supply the first excitation coil 1, the second excitation coil 2, the third excitation coil 3 and the fourth excitation coil 4. Input high-frequency pulse current to generate excitation magnetic fields in different directions in the FOV, and excite magnetic particles to generate magnetization response signals in different directions.

Among them, the high-frequency pulse current has a pulsed square wave with narrow pulse width.

Use the detection coil group to detect the magnetization response signals in the direction of the main magnetic flux and the leakage magnetic flux generated by the magnetic particles: when one excitation electromagnetic coil in the excitation electromagnetic coil group excites the magnetic particles to generate the magnetization response signal, use parallel to the excitation The detection coil array of the electromagnetic coil detects the magnetization response signal in the main magnetic flux direction generated by the magnetic particles, and the detection coil array perpendicular to the excitation electromagnetic coil detects the magnetization response signal in the leakage magnetic flux direction generated by the magnetic particle.

The DC component in the detection signal is filtered out by digital filtering technology, and the fast Fourier transform is performed on the detection signal to obtain the spectrum sequence of the detection signal: first, the detection signal transmitted to the upper computer is digitally filtered to filter out the useless detection signal. and perform fast Fourier transform on the detection signal to obtain a spectrum sequence corresponding to the detection signal, which is the response voltage signal collected by the detection coil group.

The measurement matrix of multi-channel excitation electromagnetic coils and detection coils is constructed, and the spatial distribution of magnetic particle concentration is calculated by using the spectrum sequence and measurement matrix to realize three-dimensional magnetic particle image reconstruction.

The measurement matrix of the multi-channel excitation electromagnetic coil and detection coil is constructed as follows:

Step S411 , dividing the imaging field of view of the three-dimensional magnetic particle imaging system into n reconstruction units based on the preset three-dimensional magnetic particle reconstruction image resolution. The reconstruction unit may be a square grid, a rectangular grid, or the like, and the shape of the reconstruction unit is not limited in the present invention.

The size of the reconstruction unit corresponds to the resolution of the reconstructed image, and the higher the resolution, the smaller the reconstruction unit.

Step S412, put the magnetic particle sample of the object to be imaged into the imaging field of view of the three-dimensional magnetic particle imaging system, and traverse the n reconstruction units: for each reconstruction unit, through the above-mentioned multi-channel excitation and detection-based three-dimensional magnetic particle The corresponding method of steps S10 to S30 of the imaging method acquires a set of spectrum sequences; the set of spectrum sequences constitutes a one-dimensional vector with a length of m.

Step S413: Combine the n groups of spectral sequences corresponding to the n reconstruction units to obtain the measurement matrix of the multi-channel excitation electromagnetic coil and the detection coil; the first column of the measurement matrix is the first group of spectral sequences, and the nth column is the first group of spectral sequences. The nth group of spectrum sequences, the size of the measurement matrix is m rows and n columns.

The measurement matrix is a spectrum matrix representing the mapping relationship between the spatial distribution of the magnetic particle concentration and the detected spectrum sequence.

3D magnetic particle image reconstruction, the method is as follows:

Step S421, establishing a three-dimensional magnetic particle image reconstruction equation, as shown in formula (1):

F=AC (1)

Among them, A is the measurement matrix of the multi-channel excitation electromagnetic coil and detection coil, F is the spectrum sequence detected by the multi-channel detection coil group, and C is the three-dimensional magnetic particle reconstruction image;

Step S422 , solve the three-dimensional magnetic particle reconstruction image C according to the image reconstruction equation, so as to realize the three-dimensional magnetic particle image reconstruction.

Those skilled in the art can clearly understand that, for the convenience and brevity of description, for the specific working process and related description of the method described above, reference may be made to the corresponding process in the foregoing system embodiments, which will not be repeated here.

It should be noted that, the three-dimensional magnetic particle imaging system and method based on multi-channel excitation and detection provided by the above-mentioned embodiments are only illustrated by the division of the above-mentioned functional modules. In practical applications, the above-mentioned functions can be allocated as required. It is completed by different functional modules, that is, the modules or steps in the embodiments of the present invention are decomposed or combined. For example, the modules in the above embodiments can be combined into one module, and can also be further split into multiple sub-modules to complete the above description. all or part of the functions. The names of the modules and steps involved in the embodiments of the present invention are only for distinguishing each module or step, and should not be regarded as an improper limitation of the present invention.

A device according to the third embodiment of the present invention includes:

at least one processor; and

a memory communicatively coupled to at least one of the processors; wherein,

The memory stores instructions executable by the processor, and the instructions are used to be executed by the processor to implement the above-mentioned three-dimensional magnetic particle imaging method based on multi-channel excitation and detection.

A computer-readable storage medium according to the fourth embodiment of the present invention stores computer instructions, and the computer instructions are used to be executed by the computer to realize the above-mentioned multi-channel excitation and detection-based three-dimensional Magnetic particle imaging methods.

Those skilled in the art can clearly understand that, for the convenience and brevity of description, the specific working process and relevant description of the storage device and processing device described above can refer to the corresponding process in the foregoing method embodiments, which is not repeated here. Repeat.

Those skilled in the art should be aware that the modules and method steps of each example described in conjunction with the embodiments disclosed herein can be implemented by electronic hardware, computer software or a combination of the two, and the programs corresponding to the software modules and method steps Can be placed in random access memory (RAM), internal memory, read only memory (ROM), electrically programmable ROM, electrically erasable programmable ROM, registers, hard disk, removable disk, CD-ROM, or as known in the art in any other form of storage medium. In order to clearly illustrate the interchangeability of electronic hardware and software, the components and steps of each example have been described generally in terms of functionality in the foregoing description. Whether these functions are performed in electronic hardware or software depends on the specific application and design constraints of the technical solution. Skilled artisans may use different methods of implementing the described functionality for each particular application, but such implementations should not be considered beyond the scope of the present invention.

The terms "first," "second," etc. are used to distinguish between similar objects, and are not used to describe or indicate a particular order or sequence.

The term "comprising" or any other similar term is intended to encompass a non-exclusive inclusion such that a process, method, article or device/means comprising a list of elements includes not only those elements but also other elements not expressly listed, or Also included are elements inherent to these processes, methods, articles or devices/devices.

So far, the technical solutions of the present invention have been described with reference to the preferred embodiments shown in the accompanying drawings, however, those skilled in the art can easily understand that the protection scope of the present invention is obviously not limited to these specific embodiments. Without departing from the principle of the present invention, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will fall within the protection scope of the present invention.

Claims (9)

1. A three-dimensional magnetic particle imaging system based on multi-channel excitation and detection is characterized by comprising a multi-channel excitation coil set, a multi-channel detection coil set, an alternating current power supply set, a channel control unit, a signal conditioning unit and an image reconstruction unit;

the multi-channel exciting coil group comprises a plurality of exciting electromagnetic coils with different exciting directions and is used for exciting magnetic particles along different directions;

the multi-channel detection coil set comprises a plurality of detection coil arrays, and each detection coil array in the plurality of detection coil arrays comprises a plurality of detection electromagnetic coils which are used for detecting response voltage signals of magnetic particles at different spatial positions and different angles;

the alternating current power supply set is used for supplying power to the multi-channel exciting coil set;

the channel control unit is used for switching the exciting coils in different directions in the exciting coil group to excite the magnetic particles in different directions;

the signal conditioning unit is used for amplifying and filtering the response voltage signal detected by the multi-channel detection coil group;

the image reconstruction unit is used for carrying out digital signal processing and three-dimensional magnetic particle image reconstruction according to the amplified and filtered response voltage signal;

wherein, the exciting electromagnetic coils with different exciting directions only have one exciting electromagnetic coil to generate exciting magnetic fields at a certain time;

when any exciting electromagnetic coil generates an exciting magnetic field, all the detection coil arrays simultaneously detect magnetization response voltage signals generated by magnetic particles, the detection coil arrays in the same direction as the exciting magnetic field are used for detecting magnetization response voltage signals in the main magnetic flux direction generated by the magnetic particles, and the detection coil arrays perpendicular to the exciting magnetic field are used for detecting magnetization response voltage signals in the leakage magnetic flux direction generated by the magnetic particles.

2. The multi-channel excitation and detection based three-dimensional magnetic particle imaging system of claim 1, wherein the ac power pack comprises a multi-channel signal generator and a power amplifier;

the multi-channel signal generator is used for generating a current waveform required by the electrified coil group; the current waveform is one of sine wave, triangular wave and pulse square wave;

the power amplifier is used for amplifying the current waveform generated by the multi-channel signal generator to a set size and supplying power to the multi-channel exciting coil group based on the amplified current waveform.

3. The multi-channel excitation and detection based three-dimensional magnetic particle imaging system of claim 1, further comprising a display unit;

and the display unit is used for displaying the three-dimensional magnetic particle image reconstructed by the image reconstruction unit.

4. The multi-channel excitation and detection based three-dimensional magnetic particle imaging system according to any one of claims 1-3, wherein the excitation electromagnetic coil of the multi-channel excitation coil set surrounds the imaging field of view of the three-dimensional magnetic particle imaging system;

taking the center of the imaging view field as an origin of a three-dimensional coordinate system, and respectively placing excitation electromagnetic coils of the multi-channel excitation coil set in a z-axis negative direction, a z-axis positive direction, an x-axis positive direction and an x-axis negative direction of the three-dimensional coordinate system; the direction is the main magnetic field direction generated by the exciting coil, and an object to be imaged enters an imaging field of view along the y-axis direction.

5. The multi-channel excitation and detection based three-dimensional magnetic particle imaging system according to any one of claims 1-3, wherein the detection coil arrays of the multi-channel detection coil set are placed in one-to-one correspondence with the excitation electromagnetic coils of the multi-channel excitation coil set;

each detection coil array is arranged on one side of each corresponding excitation electromagnetic coil close to an imaging field and used for detecting response voltage signals generated by magnetic particles at different spatial positions in a multi-angle mode.

6. A three-dimensional magnetic particle imaging method based on multi-channel excitation and detection, which is characterized in that based on the three-dimensional magnetic particle imaging system based on multi-channel excitation and detection as claimed in any one of claims 1-5, the three-dimensional magnetic particle imaging method comprises:

step S10, high-frequency pulse current is input to different exciting electromagnetic coils in sequence, a pulse magnetic field in a specific direction is generated in an imaging view field of the three-dimensional magnetic particle imaging system, and magnetic particles are excited to generate magnetization response voltage signals in different directions;

a step S20 of detecting, for each excitation electromagnetic coil, a magnetization response voltage signal in a main magnetic flux direction generated by magnetic particles by a detection coil array parallel to the excitation electromagnetic coil, and a magnetization response voltage signal in a leakage magnetic flux direction generated by magnetic particles by a detection coil array perpendicular to the excitation electromagnetic coil;

step S30, filtering the detected direct current component in the response voltage signal through a digital filtering technology, and performing fast Fourier transform on the detection signal to obtain a frequency spectrum sequence of the response voltage signal;

and step S40, constructing a measuring matrix of the multi-channel excitation electromagnetic coil and the detecting coil, and calculating the spatial distribution of the magnetic particle concentration by combining the frequency spectrum sequence of the response voltage signal to realize the reconstruction of the three-dimensional magnetic particle image.

7. The method according to claim 6, wherein the high-frequency pulse current has a waveform of a pulse square wave with a narrow pulse width.

8. The three-dimensional magnetic particle imaging method based on multi-channel excitation and detection as claimed in claim 6, wherein the measurement matrix of the multi-channel excitation electromagnetic coil and the detection coil is constructed by:

step S411, based on the preset resolution of the three-dimensional magnetic particle reconstructed image, dividing the imaging field of view of the three-dimensional magnetic particle imaging system into n reconstruction units;

step S412, putting the magnetic particle sample of the object to be imaged into the imaging field of view of the three-dimensional magnetic particle imaging system, traversing n reconstruction units: for each reconstruction unit, acquiring a set of spectrum sequences by a method corresponding to steps S10-S30 of the multi-channel excitation and detection based three-dimensional magnetic particle imaging method of claim 7; the group of frequency spectrum sequences form a one-dimensional vector with the length of m;

step S413, combining n groups of frequency spectrum sequences corresponding to n reconstruction units to obtain a measurement matrix of the multi-channel excitation electromagnetic coil and the detection coil; the first column of the measurement matrix is a first group of frequency spectrum sequences, the nth column is an nth group of frequency spectrum sequences, and the size of the measurement matrix is m rows and n columns.

9. The multi-channel excitation and detection based three-dimensional magnetic particle imaging method according to claim 8, wherein the three-dimensional magnetic particle image is reconstructed by:

step S421, establishing a three-dimensional magnetic particle image reconstruction equation:

F＝AC

a is a measurement matrix of a multi-channel excitation electromagnetic coil and a detection coil, F is a frequency spectrum sequence obtained by detection of the multi-channel detection coil group, and C is a three-dimensional magnetic particle reconstruction image;

and S422, solving the three-dimensional magnetic particle reconstructed image C according to the image reconstruction equation to realize the reconstruction of the three-dimensional magnetic particle image.

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