A rotating gradient magnetic particle imaging device and method based on cross-coil driving

Abstract

The application belongs to the field of magnetic particle imaging, and particularly relates to a rotating gradient magnetic particle imaging device and method based on cross-coil driving, aiming to solve the problems of difficulty in effective coding in the absence of a magnetic field region and low imaging sensitivity in magnetic particle imaging. The application comprises: superimposing the magnetic field generated by two pairs of mutually orthogonal cross-coil pairs and the uniform bias field through a magnetic field generation module to generate an imaging region magnetic field; changing the current direction of any one of the coil pairs in the cross-coil pair or changing the current type of the cross-coil pair to generate a rotating magnetic field under multiple rotating gradients through a gradient rotating module while the uniform bias field remains unchanged; obtaining scanning signals of each point in the imaging region under different magnetic fields through a scanning module; and generating the imaging result of the object to be measured based on the scanning signals under different magnetic fields through an imaging module. The application can realize high-sensitivity and reliable two-dimensional position coding MPI imaging without relying on the traditional magnetic field-free region.

Description

Technical Field

[0001] This application belongs to the field of magnetic particle imaging, and specifically relates to a rotating gradient magnetic particle imaging device and method based on cross coil driving. Background Technology

[0002] Magnetic nanoparticle imaging (MPI) is an emerging non-invasive molecular imaging technique that utilizes the nonlinear magnetization response characteristics of superparamagnetic iron oxide nanoparticles (SPIONs) to image concentration distribution. MPI technology boasts advantages such as high sensitivity, high spatial resolution, high imaging speed, and the absence of harmful radiation, giving it significant advantages over other imaging modalities. It holds a crucial research position in the field of medical imaging and possesses undeniable application value.

[0003] MPI imaging relies on generating and moving a magnetic field-free region, such as a field-free point (FFP) or field-free line (FFL), within the imaging field of view, and then reconstructing the image by spatially encoding this region. In FFP scanners, a single-point geometry is used, scanning a single pixel at a time, making the image reconstruction process simple. In FFL scanners, a line segment geometry is used, enabling simultaneous imaging of multiple pixels. Therefore, FFL scanners typically have higher sensitivity than FFP scanners, but their image reconstruction is more complex.

[0004] The core objective of MPI (Magnetic Nanoparticle Imaging) is to determine the spatial distribution of magnetic nanoparticles (MNPs). From signal detection to image generation, signal modeling is necessary for image reconstruction. Currently, there are two main basic reconstruction methods: the System Matrix (SM) method, which processes data in the frequency domain, and the x-space method, which processes data in the time domain. However, both of these imaging methods rely on the positional encoding function of fine particulate matter (FFP). The presence of FFP reduces the particle signal response range, thus limiting the improvement of imaging sensitivity. If the non-magnetic field region is completely eliminated, as in existing non-magnetic field region imaging schemes, although the response of particles throughout the field of view can be excited to obtain a stronger signal, a single, fixed-direction gradient field cannot effectively encode the two-dimensional spatial position of the signal. This makes it impossible to distinguish the signal source, thus failing to reconstruct a meaningful concentration distribution image and hindering the achievement of the imaging objective. Summary of the Invention

[0005] To address the aforementioned problems in the prior art, namely the difficulty in effectively encoding regions without magnetic fields and the low imaging sensitivity in magnetic particle imaging, one embodiment of this application provides a rotating gradient magnetic particle imaging device based on cross-coil driving, comprising:

[0006] The magnetic field generation module is used to superimpose the magnetic field generated by two pairs of mutually orthogonal cross coils with a uniform bias field to generate the magnetic field of the imaging region. The gradient rotation module is used to change the current direction of any pair of coils in a cross coil pair, or change the current type of the cross coil pair, to generate a rotating magnetic field under various rotational gradients, while keeping the uniform bias field constant. The scanning module is used to scan the object under test in the imaging field of the imaging area magnetic field and the imaging field of each rotating magnetic field, and to obtain the scanning signal of each point in the imaging area under different magnetic fields. The imaging module is used to acquire the magnetic particle signal concentration at each point based on the scanning signal under different magnetic fields, so as to generate the imaging result of the object under test.

[0007] In a preferred embodiment, the magnetic field generating module includes: a first coil pair and a cross coil pair arranged coaxially, wherein the first coil pair is used to generate a uniform bias field, and the cross coil pair includes a first cross coil pair and a second cross coil pair that are orthogonal to each other, wherein the diameter of each coil in the cross coil pair is the same and smaller than the diameter of the coil in the first coil pair.

[0008] In a preferred embodiment, the bottom of the cross coil pair is on the same plane as the bottom of the upper coil in the first coil pair.

[0009] In a preferred embodiment, the first coil pair is energized with direct current, the first cross coil pair is energized with direct current, and the second cross coil pair is energized with alternating current. The winding directions of the first cross coil pair and the second cross coil pair are opposite, and the amplitude of the alternating current of the second cross coil pair is the same as the magnitude of the direct current of the first cross coil pair.

[0010] As a preferred embodiment, the gradient rotation module is specifically used for: With the uniform bias field unchanged and the current in the second cross coil pair unchanged, the current direction of the first cross coil pair is changed to generate a first rotating magnetic field.

[0011] As a preferred embodiment, the gradient rotation module is specifically used for: The current type of the first and second cross coil pairs in the first rotating magnetic field is changed to generate a second rotating magnetic field.

[0012] As a preferred embodiment, the gradient rotation module is specifically used for: The direction of the current in the second crossed coil pair in the second rotating magnetic field is changed to generate a third rotating magnetic field.

[0013] As a preferred embodiment, the scanning module is specifically used for: The imaging field of view is divided into a uniform grid; In the imaging fields of the magnetic field of the imaging region and each rotating magnetic field, the object under test is calibrated point by point to obtain the voltage signal of each grid point in the uniform grid. The voltage signal is converted into a frequency domain signal, and the harmonic components are extracted as the scanning signal.

[0014] As a preferred embodiment, the imaging module is specifically used for: A composite matrix is ​​obtained by splicing scanning signals under different magnetic fields; A signal matrix is ​​obtained by splicing frequency domain signals under different magnetic fields; An equation is constructed where the product of the comprehensive matrix and the magnetic particle signal concentration is the signal matrix, and the magnetic particle signal concentration at each point is obtained by solving the equation.

[0015] On the other hand, one embodiment of this application proposes a rotating gradient magnetic particle imaging method based on cross-coil driving, executed by the aforementioned rotating gradient magnetic particle imaging device based on cross-coil driving, comprising: The magnetic field generated by two pairs of mutually orthogonal crossed coils is superimposed with a uniform bias field to generate the magnetic field of the imaging region. With the uniform bias field unchanged, changing the current direction of any pair of coils in the cross coil pair, or changing the current type of the cross coil pair, generates rotating magnetic fields under various rotating gradients. The object under test is scanned in the imaging field of the imaging region magnetic field and the imaging field of each rotating magnetic field to obtain the scanning signal of each point in the imaging region under different magnetic fields. Based on the scanning signals under different magnetic fields, the magnetic particle signal concentration at each point is obtained to generate the imaging results of the object under test.

[0016] Compared with the prior art, the technical solution provided in this application has at least one of the following beneficial effects: (1) A uniform bias field is introduced into the magnetic field formed by the cross coil pairs through the magnetic field generation module, and the total magnetic field of the entire imaging area is precisely adjusted to the optimal dynamic response range of the magnetic nanoparticles, ensuring that all particles in the field of view can be effectively excited. Then, the gradient rotation module, while keeping the uniform bias field stable, ingeniously controls the current of the two pairs of cross coils to realize the rotation of the gradient field in the two-dimensional plane, giving the same spatial position a unique signal fingerprint under different magnetic field directions. The realization of the "rotation gradient" is fast, accurate and repeatable, ensuring the consistency between multiple sets of measurement data, and laying a solid foundation for subsequent stable image reconstruction. Furthermore, the uniform bias field adjustment, rotation gradient encoding and image reconstruction are organically combined through the scanning module and imaging module to form a complete and universal imaging device framework. This application can excite the response of particles in the entire imaging area, improve signal utilization and sensitivity; it can also effectively encode the signal in multiple dimensions to achieve spatial resolution, and can realize MPI imaging with high sensitivity and reliable two-dimensional position encoding without relying on the traditional non-magnetic field area.

[0017] (2) This application is not only applicable to the specific coil structure described above, but its core idea can also be applied to other coil configurations or imaging systems, providing a clear and effective technical path for the development of a new generation of high-sensitivity MPI technology without magnetic field region limitations.

[0018] (3) By using the scanning module and imaging module to successfully decode the two-dimensional space of the signal source without relying on FFP / FFL based on the scanning signal under different magnetic fields, the technical bottleneck of not being able to image in the non-magnetic field area was broken and the problem of two-dimensional position encoding in the non-magnetic field area was solved.

[0019] (4) The uniform bias field fully utilizes the particle signal, significantly improving the signal strength and system sensitivity, overcoming the shortcomings of low signal utilization in traditional methods, and achieving high-sensitivity imaging in areas without traditional magnetic fields. Furthermore, the uniform bias field remains stable throughout the imaging process, providing a constant optimal operating point for the magnetic nanoparticles, reducing signal noise introduced by magnetic field fluctuations, and improving the stability and reliability of the imaging. Attached Figure Description

[0020] Other features, objects, and advantages of this application will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings: Figure 1 This is a device block diagram of a rotating gradient magnetic particle imaging device based on cross coil drive, provided in one embodiment of this application; Figure 2 This is a perspective view of a magnetic field generation module provided in one embodiment of this application; Figure 3 This is a front view of a magnetic field generation module provided in one embodiment of this application; Figure 4 This is a three-dimensional structural schematic diagram of an imaging region magnetic field generation device provided in one embodiment of this application; Figure 5 This is a front view of an imaging region magnetic field generating device provided in one embodiment of this application; Figure 6 This is a flowchart of a rotating gradient magnetic particle imaging method based on cross coil driving, provided in one embodiment of this application; Figure 7 This is a schematic diagram of the structure of a computer system used to implement the embodiments of the devices, methods, and electronic devices of this application. Detailed Implementation

[0021] The present application will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are for illustrative purposes only and are not intended to limit the invention. Furthermore, it should be noted that, for ease of description, only the parts relevant to the invention are shown in the accompanying drawings.

[0022] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0023] This application provides a rotating gradient magnetic particle imaging device based on cross-coil driven imaging. A magnetic field generation module superimposes the magnetic fields generated by two pairs of orthogonal cross-coils onto a uniform bias field to generate the magnetic field of the imaging region. A gradient rotation module, while keeping the uniform bias field constant, changes the current direction or type of any pair of coils in the cross-coil pairs to generate rotating magnetic fields under various rotating gradients. A scanning module scans the object under test within the imaging region's magnetic field and the imaging field of each rotating magnetic field, acquiring scanning signals at each point within the imaging region under different magnetic fields. An imaging module, based on the scanning signals under different magnetic fields, obtains the magnetic particle signal concentration at each point to generate the imaging result of the object under test. This application can excite the response of particles throughout the imaging region, improving signal utilization and sensitivity; it can also effectively encode signals in multiple dimensions to achieve spatial resolution, enabling high-sensitivity and reliable two-dimensional position encoding MPI imaging without relying on traditional non-magnetic field regions.

[0024] To more clearly explain the rotating gradient magnetic particle imaging device based on cross-coil drive in this application, the following will be combined with... Figure 1 The modules in the embodiments of this application are described in detail below.

[0025] The rotating gradient magnetic particle imaging device based on cross-coil drive according to the first embodiment of this application includes: The magnetic field generation module 100 is used to superimpose the magnetic field generated by two pairs of mutually orthogonal cross coils with a uniform bias field to generate the magnetic field of the imaging region.

[0026] like Figure 2 As shown, the magnetic field generating module includes a first coil pair and a crossed coil pair placed coaxially. The first coil pair, also called the large coil, is used to generate a uniform bias field. In one embodiment of this application, the first coil pair consists of two coils connected in series, with 85x2 turns, an inner diameter of 470mm, an outer diameter of 600mm, a spacing of 180mm between the two coils, and a wire diameter of 4mm. Please refer to [reference needed]. Figure 3 The front view shown depicts a crossover coil pair located in the middle of the first coil pair. The bottom of the crossover coil pair is on the same plane as the bottom of the upper coil in the first coil pair. It includes a first crossover coil pair and a second crossover coil pair that are orthogonal to each other. Figure 2 The two coils located diagonally in the middle form a crossover coil pair. The coils in these two crossover coil pairs have identical electromagnetic properties, and the two coils in each pair have the same electromagnetic magnitude, opposite winding directions, and are connected in series to generate gradient magnetic fields in opposite directions. The coils in each crossover coil pair have the same diameter, which is smaller than the diameter of the coils in the first coil pair. For example, each crossover coil has 290 x 4 turns, an inner diameter of 24 mm, an outer diameter of 90 mm, a height of 90 mm, and a wire diameter of 3 mm.

[0027] In terms of spatial layout, two pairs of cross coils are placed closely together at a 90-degree angle. Centered on the central axis of the cross coils, at a depth of 4cm from the lower surface of the cross coils, an imaging area is formed. The size of this imaging area can be set as a 4cm×4cm square.

[0028] The magnetic field generation module has a reasonable structural layout, which can effectively ensure the synergy between uniform bias field adjustment and gradient field control.

[0029] In an initial operating mode, the first coil pair is energized with direct current (DC), the first cross coil pair is energized with DC, and the second cross coil pair is energized with alternating current (AC). The amplitude of the AC current in the second cross coil pair is the same as the magnitude of the DC current in the first cross coil pair. The magnetic field generation module is used to generate a basic magnetic field for the imaging region.

[0030] Specifically, a direct current (DC) is applied to the first coil pair to generate a stable, uniform bias field. The main function of this bias field is to precisely adjust the total magnetic field strength of the subsequent superimposed magnetic field to the optimal dynamic response range of the SPIONs, based on their inherent magnetization characteristics. This ensures that all magnetic particles within the field of view can be effectively excited. Therefore, the magnitude of the DC current applied is determined by the coil characteristics and the inherent characteristics of the SPIONs; for example, 8A of DC current is applied in this embodiment. Simultaneously, a DC current (e.g., 10A, generating a gradient intensity of 0.3T / m) is applied to the first cross coil pair to construct a gradient field in an initial dimension (e.g., the X-axis direction); and a sinusoidal alternating current of the same amplitude (10A) and a specific frequency (e.g., 5kHz) is applied to the second cross coil pair to construct a sinusoidal excitation field. The superposition of these three magnetic fields constitutes the total magnetic field of the imaging region, i.e., the imaging region magnetic field obtained in this embodiment.

[0031] The gradient rotation module 200 is used to change the current direction of any pair of coils in a cross coil pair, or change the current type of the cross coil pair, to generate a rotating magnetic field under various rotational gradients, while keeping the uniform bias field constant.

[0032] Optionally, the gradient rotation module can generate rotating magnetic fields under various rotational gradients by changing the current configuration of the cross coil pairs.

[0033] In one embodiment of this application, while keeping the current parameters of the first coil pair (uniform bias field) and the second cross coil pair (excitation field) constant, a first rotating magnetic field can be generated simply by reversing the direction of the direct current supplied to the first cross coil pair. The gradient direction of this magnetic field is rotated 180° along the initial X-axis direction.

[0034] By maintaining the current type of the first coil pair as DC and the amplitude as 8A, the uniform bias field is kept stable, and the basic adjustment state of the total magnetic field is not affected. This provides a constant optimal operating point for the magnetic nanoparticles, reduces signal noise introduced by magnetic field fluctuations, and improves the stability and reliability of imaging.

[0035] The current supplied to the second cross coil remains unchanged at 10A, 5kHz sinusoidal alternating current, while the current supplied to the first cross coil remains unchanged at 10A direct current, but its current direction is changed. At this time, the superimposed total magnetic field (uniform bias field + reverse X-axis gradient field + sinusoidal excitation field) changes, generating the first rotating magnetic field.

[0036] In one embodiment of this application, the gradient rotation module changes the current type of the first cross coil pair and the second cross coil pair in the first rotating magnetic field while keeping the current parameters of the first coil pair unchanged, thereby generating a second rotating magnetic field.

[0037] By swapping the functions of two pairs of crossed coils, a 90° dimensional switch is achieved. Specifically, the current type of the first crossed coil pair is changed from DC to AC (as an excitation field), while the current type of the second crossed coil pair is changed from AC to DC (to construct a gradient field in the Y-axis direction), thereby generating a second rotating magnetic field.

[0038] Similarly, the current type of the first coil pair remains constant at DC, and the amplitude remains constant at 8A to ensure the stability of the uniform bias field. By passing a 10A, 5kHz sinusoidal alternating current through the first cross coil pair, a sinusoidal excitation field is constructed. By passing a 10A, 0.3T / m gradient DC current through the second cross coil pair, a Y-axis gradient field is constructed. The uniform bias field and this combined magnetic field are superimposed to form a new total magnetic field, thereby generating the third gradient field.

[0039] In one embodiment of this application, the current direction of the second cross coil pair in the second rotating magnetic field is changed to generate a third rotating magnetic field. Based on the second rotating magnetic field, the current of the first cross coil pair (excitation field) is kept constant, and only the direction of the DC current flowing into the second cross coil pair is reversed to generate the third rotating magnetic field, the gradient direction of which is rotated 180° along the Y-axis.

[0040] Based on the second rotating magnetic field, the current type of the first coil pair remains constant at DC and the amplitude remains constant at 8A to ensure the stability of the uniform bias field. The first cross coil pair is kept at 10A and 5kHz sinusoidal AC, and the current in the second cross coil pair remains at 10A DC, but its current direction is changed so that the Y-axis gradient field is reversed by 180°. At this time, the superimposed total magnetic field (uniform bias field + reversed Y-axis gradient field + sinusoidal excitation field) changes, generating the third rotating magnetic field.

[0041] Through the above four working modes (initial magnetic field, first, second, and third rotating magnetic fields), the rotation of the gradient field in the two-dimensional plane was realized, laying the foundation for subsequent position encoding and high-sensitivity imaging.

[0042] The scanning module 300 is used to scan the object under test in the imaging field of the imaging region magnetic field and the imaging field of each rotating magnetic field, and to obtain the scanning signal of each point in the imaging region under different magnetic fields.

[0043] Optionally, the scanning module divides the imaging field of view into a uniform grid; within the imaging field of the magnetic field of the imaging region and the imaging field of each rotating magnetic field, the voltage signal of each grid point in the uniform grid is obtained by point-by-point calibration of the object under test; the voltage signal is converted into a frequency domain signal, and the harmonic components are extracted as the scanning signal.

[0044] In one embodiment of this application, the scanning module divides the 4cm×4cm imaging field of view (i.e., the imaging area formed by the magnetic field generation module) into an 11×11 grid. Then, following a point-by-point calibration method, the object to be tested is sequentially placed into each grid point of the imaging area.

[0045] As an example, the test object can be a dot phantom containing a standard concentration of SPIONs, such as a cube with a side length of 2 mm containing 30 mg / mL SPIONs, or a blood vessel phantom containing a certain concentration of SPIONs with a thickness of 3 mm.

[0046] Under the four magnetic field conditions described above (i.e., the imaging region magnetic field and the three rotating magnetic fields), the time-domain voltage signal generated by the standard point-like phantom at each grid point was measured and acquired. Subsequently, these time-domain voltage signals were converted into frequency-domain signals through Fourier transform, and K usable harmonic components were extracted from them. These harmonic components constitute the scanning signal of that point.

[0047] All the useful information about the nonlinear response of magnetic particles lies in the intensity and phase of the harmonics. The fundamental frequency, mainly derived from the direct feedthrough of the excitation field, is usually filtered out or ignored. The generation of higher harmonics, however, is entirely due to the presence of magnetic particles; they are the "fingerprint signals" of the imaging. A continuous frequency domain signal may contain thousands of data points, but the useful information lies only at a few dozen harmonic frequencies. Therefore, by extracting harmonic components, efficient data compression and noise reduction can be achieved.

[0048] In the embodiments of this application, the value of K can be 20, that is, the first 20 (or the 20 most useful) harmonic components are extracted from the frequency domain signal to form the scanning signal of each point under the corresponding magnetic field.

[0049] The imaging module 400 is used to acquire the magnetic particle signal concentration at each point based on the scanning signal under different magnetic fields, so as to generate the imaging result of the object under test.

[0050] Optionally, the imaging module stitches together the scanning signals under different magnetic fields to obtain a comprehensive matrix; stitches together the frequency domain signals under different magnetic fields to obtain a signal matrix; constructs an equation that the product of the comprehensive matrix and the magnetic particle signal concentration is the signal matrix, and solves it to obtain the magnetic particle signal concentration at each point.

[0051] After acquiring the scanning signals of each point within the imaging region under different magnetic fields, the scanning signals of all grid points under any given magnetic field are combined to form a scanning signal matrix corresponding to that magnetic field. , , and The shape of any scan signal matrix is Where N is the total number of grid points, and in this embodiment, N is 121. Further, the scan signal matrices are concatenated to obtain a composite matrix. Its shape is .

[0052] When imaging the object under test, the scanning module places the object within the imaging field of view and scans it under the same four magnetic field conditions to acquire four raw signals. Each raw signal undergoes the same processing (Fourier transform and harmonic extraction) to obtain four frequency domain signals. , , and The shape of each signal is .

[0053] Furthermore, the four measured frequency domain signals are spliced ​​together to obtain a signal matrix. Its shape is .

[0054] Since the system matrix and signal satisfy a linear relationship under the same magnetic field conditions, a linear equation can be constructed. Where c is the vector to be solved, representing the magnetic particle concentration distribution at various locations within the imaging region, and its shape is... The magnetic particle signal concentration at each point can be obtained by calculating c using linear equation solving methods, including but not limited to the Kaczmarz algorithm.

[0055] Furthermore, based on the acquired magnetic particle signal concentration, the imaging module reconstructs a two-dimensional high-sensitivity image of the magnetic particle concentration within the object.

[0056] Please see Figure 4 and Figure 5 , Figure 4 This is a three-dimensional structural diagram of an imaging region magnetic field generating device according to one embodiment of this application. Figure 5 This is the main view of the device, as shown in the figure. The device has a stable mechanical frame, mainly including a base 501, multiple support columns 502, and upper and lower platform structures supported by the support columns. The entire structure forms an open scanning space. The first coil pair 401 constitutes the main body of the upper and lower platform structures, with its upper and lower coils coaxially arranged to define the scanning area for placing the object to be measured. The cross coil pair 402 is installed in the central area of ​​the upper platform and is located inside the upper coil of the first coil pair. This layout ensures the accurate superposition of the gradient field and the uniform bias field. Both the upper and lower platforms are provided with wiring ports 503 for connecting external power supplies to power the first coil pair and the cross coil pair, respectively, to generate the required composite magnetic field.

[0057] When the device is working, the displacement stage (not shown in the figure) carrying the object under test can move between the upper and lower coils of the first coil pair, that is, within the scanning space directly below the cross coil pair, thereby realizing scanning imaging of different positions of the object under test. Through the coordinated work of each module, the magnetic particle imaging result of the object under test is finally obtained.

[0058] Please see Figure 6 The rotating gradient magnetic particle imaging method based on cross-coil driving according to the second embodiment of this application is used to perform the above-mentioned rotating gradient magnetic particle imaging device based on cross-coil driving, and includes steps S10-S40, each step of which is described in detail below: Step S10: The magnetic field generated by two pairs of mutually orthogonal cross coils is superimposed with the uniform bias field to generate the magnetic field of the imaging region.

[0059] Step S20: Under the condition that the uniform bias field remains unchanged, change the current direction of any pair of coils in the cross coil pair, or change the current type of the cross coil pair, to generate a rotating magnetic field under various rotating gradients.

[0060] Step S30: Scan the object to be tested in the imaging field of the imaging region magnetic field and the imaging field of each rotating magnetic field to obtain the scanning signal of each point in the imaging region under different magnetic fields.

[0061] Step S40: Based on the scanning signals under different magnetic fields, obtain the magnetic particle signal concentration at each point to generate the imaging result of the object under test.

[0062] Those skilled in the art will understand that, for the sake of convenience and brevity, the specific working process and related descriptions of the methods described above can be found in the corresponding processes in the foregoing device embodiments, and will not be repeated here.

[0063] It should be noted that the rotating gradient magnetic particle imaging device and method based on cross-coil drive provided in the above embodiments are only illustrative examples of the above functional module division. In practical applications, the above functions can be assigned to different functional modules as needed, that is, the modules or steps in the embodiments of this application can be further decomposed or combined. For example, the modules in the above embodiments can be merged into one module, or further divided into multiple sub-modules to complete all or part of the functions described above. The names of the modules and steps involved in the embodiments of this application are only for distinguishing each module or step and are not considered as an improper limitation of this application.

[0064] An electronic device according to a third embodiment of this application includes: At least one processor; and a memory communicatively connected to at least one of the processors; The memory stores instructions that can be executed by the processor to implement the above-described rotating gradient magnetic particle imaging method based on cross-coil drive.

[0065] A computer-readable storage medium according to a fourth embodiment of this application stores computer instructions for execution by the computer to implement the above-described rotating gradient magnetic particle imaging method based on cross-coil drive.

[0066] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the specific working processes and related descriptions of the electronic devices, computer-readable storage media, and computer program products described above can be referred to the corresponding processes in the foregoing method embodiments, and will not be repeated here.

[0067] The following is for reference. Figure 7 It shows a schematic diagram of the structure of a computer system for implementing embodiments of the devices, methods, and electronic devices of this application. Figure 7 The server shown is merely an example and should not impose any limitations on the functionality and scope of use of the embodiments of this application.

[0068] like Figure 7 As shown, the computer system includes a Central Processing Unit (CPU) 701, which can perform various appropriate actions and processes based on programs stored in Read Only Memory (ROM) 702 or programs loaded from storage section 708 into Random Access Memory (RAM) 703. The RAM 703 also stores various programs and data required for system operation. The CPU 701, ROM 702, and RAM 703 are interconnected via a bus 704. An Input / Output (I / O) interface 705 is also connected to the bus 704.

[0069] The following components are connected to I / O interface 705: an input section 706 including a keyboard, mouse, etc.; an output section 707 including a cathode ray tube (CRT), liquid crystal display (LCD), and speakers, etc.; a storage section 708 including a hard disk, etc.; and a communication section 709 including a network interface card such as a LAN (Local Area Network) card and a modem, etc. The communication section 709 performs communication processing via a network such as the Internet. A drive 710 is also connected to I / O interface 705 as needed. A removable medium 711, such as a disk, optical disk, magneto-optical disk, semiconductor memory, etc., is installed on drive 710 as needed so that computer programs read from it can be installed into storage section 708 as needed.

[0070] Specifically, according to embodiments of this application, the processes described above with reference to the flowcharts can be implemented as computer software programs. For example, embodiments of this application include a computer program product comprising a computer program carried on a computer-readable medium, the computer program containing program code for performing the methods shown in the flowcharts. In such embodiments, the computer program can be downloaded and installed from a network via communication section 709, and / or installed from removable medium 711. When the computer program is executed by central processing unit (CPU) 701, it performs the functions defined in the methods of this application. It should be noted that the computer-readable medium described above in this application can be a computer-readable signal medium or a computer-readable storage medium, or any combination of the two. A computer-readable storage medium can be, for example,, but not limited to, an electrical, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any combination thereof. More specific examples of computer-readable storage media may include, but are not limited to: electrical connections having one or more wires, portable computer disks, hard disks, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), optical fiber, portable compact disk read-only memory (CD-ROM), optical storage devices, magnetic storage devices, or any suitable combination thereof. In this application, a computer-readable storage medium can be any tangible medium containing or storing a program that can be used by or in connection with an instruction execution system, apparatus, or device. In this application, a computer-readable signal medium may include a data signal propagated in baseband or as part of a carrier wave, carrying computer-readable program code. Such propagated data signals can take various forms, including but not limited to electromagnetic signals, optical signals, or any suitable combination thereof. A computer-readable signal medium can also be any computer-readable medium other than a computer-readable storage medium, which can send, propagate, or transmit a program for use by or in connection with an instruction execution system, apparatus, or device. The program code contained on a computer-readable medium can be transmitted using any suitable medium, including but not limited to: wireless, wire, optical fiber, RF, etc., or any suitable combination thereof.

[0071] Computer program code for performing the operations of this application can be written in one or more programming languages ​​or a combination thereof. These programming languages ​​include object-oriented programming languages ​​such as Java, Smalltalk, and C++, as well as conventional procedural programming languages ​​such as C or similar languages. The program code can be executed entirely on the user's computer, partially on the user's computer, as a standalone software package, partially on the user's computer and partially on a remote computer, or entirely on a remote computer or server. In cases involving remote computers, the remote computer can be connected to the user's computer via any type of network, including a local area network (LAN) or a wide area network (WAN), or it can be connected to an external computer (e.g., via the Internet using an Internet service provider).

[0072] The flowcharts and block diagrams in the accompanying drawings illustrate the architecture, functionality, and operation of possible implementations of devices, methods, and computer program products according to various embodiments of this application. In this regard, each block in a flowchart or block diagram may represent a module, segment, or portion of code containing one or more executable instructions for implementing a specified logical function. It should also be noted that in some alternative implementations, the functions indicated in the blocks may occur in a different order than those indicated in the drawings. For example, two consecutively indicated blocks may actually be executed substantially in parallel, and they may sometimes be executed in reverse order, depending on the functions involved. It should also be noted that each block in the block diagrams and / or flowcharts, and combinations of blocks in the block diagrams and / or flowcharts, can be implemented using a dedicated hardware-based system that performs the specified function or operation, or using a combination of dedicated hardware and computer instructions.

[0073] The terms “first”, “second”, etc., are used to distinguish similar objects, not to describe or indicate a specific order or sequence.

[0074] The term "comprising" or any other similar term is intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus / device that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent in such process, method, article, or apparatus / device.

[0075] The technical solutions of this application have been described above with reference to the preferred embodiments shown in the accompanying drawings. However, it will be readily understood by those skilled in the art that the scope of protection of this application is obviously not limited to these specific embodiments. Without departing from the principles of this application, 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 all fall within the scope of protection of this application.

Claims

1. A rotating gradient magnetic particle imaging device based on cross-coil drive, characterized in that, include: The magnetic field generation module is used to superimpose the magnetic field generated by two pairs of mutually orthogonal cross coils with a uniform bias field to generate the magnetic field of the imaging region. The gradient rotation module is used to change the current direction of any pair of coils in the cross coil pair, or change the current type of the cross coil pair, to generate a rotating magnetic field under various rotation gradients, while keeping the uniform bias field unchanged. The scanning module is used to scan the object under test within the imaging field of the magnetic field of the imaging region and each rotating magnetic field, respectively, and to obtain the scanning signal of each point in the imaging region under different magnetic fields. The imaging module is used to acquire the magnetic particle signal concentration at each point based on the scanning signal under different magnetic fields, so as to generate the imaging result of the object under test.

2. The rotating gradient magnetic particle imaging device based on cross-coil drive according to claim 1, characterized in that, The magnetic field generating module includes: a first coil pair and a cross coil pair placed coaxially, wherein the first coil pair is used to generate a uniform bias field, and the cross coil pair includes a first cross coil pair and a second cross coil pair that are orthogonal to each other, wherein the diameter of each coil in the cross coil pair is the same and smaller than the diameter of the coil in the first coil pair.

3. A rotating gradient magnetic particle imaging device based on cross-coil drive according to claim 2, characterized in that, The bottom of the cross coil pair is on the same plane as the bottom of the upper coil in the first coil pair.

4. A rotating gradient magnetic particle imaging device based on cross-coil drive according to claim 2, characterized in that, The first coil pair is energized with direct current, the first cross coil pair is energized with direct current, and the second cross coil pair is energized with alternating current. The winding directions of the first cross coil pair and the second cross coil pair are opposite, and the amplitude of the alternating current of the second cross coil pair is the same as the magnitude of the direct current of the first cross coil pair.

5. A rotating gradient magnetic particle imaging device based on cross-coil drive according to claim 2, characterized in that, The gradient rotation module is specifically used for: With the uniform bias field unchanged and the current of the second cross coil pair unchanged, the current direction of the first cross coil pair is changed to generate a first rotating magnetic field.

6. A rotating gradient magnetic particle imaging device based on cross-coil drive according to claim 5, characterized in that, The gradient rotation module is specifically used for: The current type of the first cross coil pair and the second cross coil pair in the first rotating magnetic field is changed to generate a second rotating magnetic field.

7. A rotating gradient magnetic particle imaging device based on cross-coil drive according to claim 6, characterized in that, The gradient rotation module is specifically used for: The direction of the current in the second cross coil pair in the second rotating magnetic field is changed to generate a third rotating magnetic field.

8. A rotating gradient magnetic particle imaging device based on cross-coil drive according to claim 1, characterized in that, The scanning module is specifically used for: The imaging field of view is divided into a uniform grid; Within the imaging fields of the magnetic field of the imaging region and each rotating magnetic field, the object under test is calibrated point by point to obtain the voltage signal of each grid point in the uniform grid. The voltage signal is converted into a frequency domain signal, and the harmonic components are extracted as the scanning signal.

9. A rotating gradient magnetic particle imaging device based on cross-coil drive according to claim 8, characterized in that, The imaging module is specifically used for: A composite matrix is ​​obtained by splicing scanning signals under different magnetic fields; A signal matrix is ​​obtained by splicing frequency domain signals under different magnetic fields; An equation is constructed where the product of the comprehensive matrix and the magnetic particle signal concentration is the signal matrix, and the magnetic particle signal concentration at each point is obtained by solving the equation.

10. A rotating gradient magnetic particle imaging method based on cross-coil driving, executed by a rotating gradient magnetic particle imaging device based on cross-coil driving as described in any one of claims 1-9, characterized in that, include: The magnetic field generated by two pairs of mutually orthogonal crossed coils is superimposed with a uniform bias field to generate the magnetic field of the imaging region. With the uniform bias field unchanged, changing the current direction of any pair of coils in the cross coil pair, or changing the current type of the cross coil pair, generates rotating magnetic fields under various rotating gradients. The object under test is scanned within the imaging field of the magnetic field of the imaging region and the imaging field of each rotating magnetic field to obtain the scanning signal of each point in the imaging region under different magnetic fields. Based on the scanning signals under different magnetic fields, the magnetic particle signal concentration at each point is obtained to generate the imaging results of the object under test.

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