Normal Conducting Electromagnet System

Abstract

To provide a magnetic resonance imaging (MRI) system including normal conduction solenoidal electromagnets for whole body MRI.SOLUTION: A ferromagnetic material may be provided within the envelope of the electromagnet. The system may be configured to have a magnetic field strength of at least 0.05 Tesla, and the main electromagnetic field may be generated by layered, rather than bundled, conductors. The electromagnet configuration may be fabricated using a non-metallic coil former, e.g., fiberglass, and may be assembled to form a rigid body from multiple layers of conductors, all secured together with epoxy. The electromagnet may be bisected into two spaced apart portions, and the two portions may be spaced apart by a fixed structure, such as carbon fiber. The power supply for the electromagnet may have a current variation of at least 1 / 10,000th (1 per milliard) at frequencies of 180 Hz or more without requiring an additional current filter.SELECTED DRAWING: None

Description

[Technical field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application is a joint venture of U.S. Provisional Patent Application No. 62 / 672,525 (filed May 16, 2018, Title of invention: "Resistive Electromagnet Systems a nd Methods) and U.S. Provisional Patent Application No. 62 / 677,546 (filing date: May 29, 2018, Invention name: "Resistive Electromagnet Priority was claimed based on the "Patent Design and Construction" and both provisional The benefit of both provisional patent applications is claimed, the entire contents of which are incorporated herein by reference. . [Background technology]

[0002] Magnetic resonance imaging (MRI) or nuclear magnetic resonance imaging uses radio frequency pulses, a strong magnetic field ( A weak gradient field is applied to the strong magnetic field to modify it, localize the phase and frequency, and encode or and decoding (using bodily tissue interactions to create two-dimensional or three-dimensional images of the inside of a patient's body). Magnetic resonance imaging is a non-invasive imaging technique that acquires images, spectral signals and projection images. It is particularly useful for imaging soft tissues and may be used to diagnose disease. When moving internal structures of a patient need to be imaged to separate the Real-time MRI or cine MRI may be used. Real-time MRI is also used in radiology. In addition to therapeutic or interventional procedures such as image-guided surgery, may also be used to develop treatment plans. Summary of the Invention [Means for solving the problem]

[0003] An electromagnet configuration is disclosed that may be utilized in a magnetic resonance imaging system. A normal conductive solenoid-shaped electromagnet for whole-body MRI having a magnet, and a magnet provided in the envelope of the electromagnet. and a ferromagnetic material disposed therein. The electromagnet may be gapped; The ferromagnetic material may be steel. In some variations, the electromagnet has a single It may be arranged for current flow to occur only in the circumferential direction.

[0004] The electromagnet is a normal conducting solenoid type for whole body MRI with a magnetic field strength of at least 0.05 Tesla. The electromagnet may be configured as an electromagnet having a conductor that generates the main electromagnetic field of the electromagnet. The main electromagnetic field is not generated by a bundle of conductors. The magnetic field may be generated by layered conductors (eg, less than 10 layers).

[0005] The electromagnet configurations disclosed herein are preferably constructed using a non-metallic material, such as a fiberglass former, that supports a conductor. A coil former may be used. Layered conductors and non-metallic coil formers can be secured in place with epoxy. Assemble them to form a rigid body. The electromagnet is divided into two parts. The two portions may be separated by a fastening structure, the fastening structure being a carbon In one embodiment, the conductor utilized may be a conductor having a cross-sectional area of ​​0. May be greater than .5 square centimeters.

[0006] In another embodiment, the magnetic resonance imaging system has a magnetic field strength of at least 0.05 Tesla. The laser may include a normal conducting solenoid-shaped electromagnet for whole-body MRI. To generate the main electromagnetic field of an electromagnet, covering at least 50% of the magnet's envelope The conductor is

[0007] In the particular system disclosed herein, the power supply that powers the resistive electromagnet comprises: Current fluctuations at frequencies above 180Hz are greater than 1 part in 10,000 (1 per milliad) and a current filter can be provided separately from the filtering function realized by the normal conducting electromagnet itself. The power source may be a single channel power source and may not include an active In certain embodiments, the system may not include a battery. The resistive electromagnet may be connected to a battery, and the system The battery may be configured to be rechargeable by a power source. The system may include a fuel cell. The fuel cell is connected between a power source and a resistive electromagnet. The sensor may be configured to be disposed at

[0008] Examples of the current subject matter include, but are not limited to, those consistent with those described herein. The method and process implementing one or more of the described features can be implemented on one or more machines (e.g. A tangibly embodied, machine-readable executable program configured to cause a computer (e.g., Similarly, an article including one or more processors and the one or A computer system comprising: one or more memories coupled to a plurality of processors. The memory may include a computer readable storage medium and may be adapted to perform the processes described herein. One or more programs that cause one or more processors to execute one or more of the following: The system may contain, encode, store, etc., a program consistent with one or more embodiments of the present subject matter. Corresponding computer-implemented methods may be implemented on one or more data processors. The data processor may be located in one computing system or on multiple computing systems. These multiple computing systems exist The systems may be interconnected, and multiple computers may be connected via one or more connections. By directly connecting one or more of the following operating systems together, data and / or Alternatively, commands or other instructions may be exchanged. The connection is a connection over a network (e.g., the Internet, wireless wide area networks, etc.). network, local area network, wide area network, wired network Work, etc.), but are not limited to these.

[0009] For details of one or more variations of the subject matter described herein, see the accompanying drawings and the following: Other features and advantages of the subject matter described herein are set forth in the specification and throughout the specification. The features of the presently disclosed subject matter will be apparent from the accompanying drawings and claims. The present invention is described for illustrative purposes with reference to certain embodiments, but is not limited to such features. It should be readily understood that the claims following this disclosure are not intended to limit the scope of the subject matter sought to be protected. It defines the range. [Brief description of the drawings]

[0010] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate exemplary embodiments of the present invention and are not to be construed as limiting the present invention. The subject matter is illustrated and, in combination with the specification, corresponds to the disclosed embodiments. The drawings are illustrative of some of the principles of the invention.

[0011] [Figure 1] FIG. 1 shows a simplified perspective view of an example magnetic resonance imaging system in accordance with certain aspects of the present disclosure.

[0012] [Diagram 2] FIG. 2 is a simplified cross-sectional view showing an example of an electromagnet that generates a main magnetic field for a solenoid magnet having a gap as shown in FIG.

[0013] [Diagram 3] 1A-1D show simplified cross-sectional and perspective views illustrating layers of an electromagnet according to certain aspects of the present disclosure.

[0014] [Figure 4] 1 is a simplified cross-sectional view illustrating an electromagnet with additional ferromagnetic material to suppress fringe fields, in accordance with certain aspects of the present disclosure.

[0015] [Diagram 5] FIG. 1 shows a simplified perspective view of an example of a magnetic resonance imaging system incorporating an example of a radiation therapy interventional device according to certain aspects of the present disclosure.

[0016] [Figure 6] FIG. 2 is a simplified perspective view showing two example conductor halves of a solenoidal electromagnet with a gap, according to certain embodiments of the present disclosure.

[0017] [Figure 7A] FIG. 2 is a simplified diagram illustrating an example of the structure of a portion of an electromagnet according to certain aspects of the present disclosure.

[0018] [Figure 7B] FIG. 1 illustrates a simplified perspective view of one of two halves of an electromagnet having an indirect cooling system with serpentine channels in accordance with certain embodiments of the present disclosure.

[0019] [Figure 7C]FIG. 1 is a simplified perspective view illustrating an indirect cooling system having serpentine channels between layers of electromagnets, in accordance with certain aspects of the present disclosure.

[0020] [Figure 8A] 1A-1C show two example arrangements for conductors at adjacent levels within an electromagnet according to certain embodiments of the present disclosure.

[0021] [Figure 8B] 1A-1C are simplified diagrams illustrating an example of the structure of a portion of an electromagnet having a radial S-bend, in accordance with certain embodiments of the present disclosure.

[0022] [Figure 8C] FIG. 2 is a simplified diagram illustrating an example of an electromagnet structure according to certain aspects of the present disclosure.

[0023] [Figure 9] FIG. 2 is a simplified diagram illustrating an example of another configuration of a portion of an electromagnet according to certain aspects of the present disclosure.

[0024] [Figure 10] FIG. 2 is a simplified circuit diagram illustrating an example of an electromagnet and a power supply with associated filtering, in accordance with certain aspects of the present disclosure.

[0025] [Figure 11] FIG. 1 illustrates a simplified example of the combined use of multiple batteries in powering an electromagnet, in accordance with certain aspects of the present disclosure.

[0026] [Figure 12] FIG. 2 illustrates a simplified diagram of an embodiment in which a fuel cell is provided between an electromagnet and a power source, in accordance with certain aspects of the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0027] This disclosure relates to various systems, devices, methods and computers utilized with electromagnets. Certain embodiments of the techniques described herein may be utilized in the data software. has utility when used in conjunction with magnets used in magnetic resonance imaging (MRI) However, it is contemplated that these techniques may also be utilized in electromagnets for other applications.

[0028] The particular type of MRI magnet described herein takes advantage of the above technology: , a solenoidal (i.e. cylindrical) normal conducting electromagnet (e.g. permanent magnet, superconducting electromagnet (This is to be distinguished from magnets, which are magnets with a magnetic field, and non-solenoidal electromagnets such as dipole magnets.) When the terms "solenoid" or "solenoid-like" are used in this context, it is not intended to simply refer to a particular The MRI is of such a configuration (i.e. cylindrical). is in no way limited to magnet configurations commonly described as helical (e.g., a single helically wound conductor). The techniques described herein are not intended to be used with MRI electromagnetic devices of any size. Although it may also be used for stones, the primary embodiment described here is for magnets for whole-body MRI systems. The term "whole body" as used herein refers to imaging of a particular part of the body. Miniature MRI for veterinary use, research, etc. (e.g. O-Scan by Esaote) Not a research MRI, but a regular size magnetic resonance imaging system (e.g., Siemens Healthineers' Magnetom Aera and GE's Sign a) means

[0029] For whole-body MRI magnets, the techniques described herein can be used at any MRI field strength. However, imaging may be adversely affected at levels below 0.05 Tesla. However, when it exceeds 0.5 Tesla, the required power may become large due to the normal conducting electromagnet. In two specific examples of the normal conducting solenoid electromagnet described in this specification, the magnetic field The strengths are 0.12T and 0.2T.

[0030] The disclosed technology is suitable for use in conventional solenoid-type MRI systems used for diagnostic purposes. However, as in the system shown in FIG. Magnets having a "gap" in this disclosure may be particularly useful in magnetoid systems. When referring to a bipolar magnet configuration, as opposed to what is typically referred to as an "open" MRI system, It is intended to include a solenoid-like electromagnet having a gap (as shown in FIG. 1). The system as described herein, the system with gaps, is an MRI Highly useful for interventional applications such as guided radiation therapy and MRI-guided surgery An example of such a radiation therapy system is shown in FIG. The gantry on which the magnetic shield structure, including the accelerator components, is mounted is in the gap. The figure shows how it is installed inside the

[0031] The techniques described herein apply primarily to electromagnets used in MRI, but these specific The features can also be used in suitable magnet configurations regardless of purpose. For example, more versatile magnets A system is a device that is used in research, industry, or practical applications, such as magnetic switching, motors, generators, etc. This may include systems used in electronics, repeaters, speakers, magnetic separators, etc. .

[0032] FIG. 1 illustrates an embodiment of a magnetic resonance imaging system (MRI) 100 in accordance with certain aspects of the present disclosure. FIG. 1 is a diagram showing an embodiment. In FIG. 1, an MRI 100 includes a main electromagnet 102 and a gradient coil. The MRI 100 includes a coil assembly 104 and an RF coil system 106. , there is a patient couch 108 on which a human patient 110 lies.

[0033] The main electromagnet 102 of the MRI 100 has a gap 116 as shown in FIG. The magnet may be a solenoid-like electromagnet having a gap separated by a gap 114. The term "top" as used herein refers to a top of the type illustrated in FIGS. 1 shows the gap 116 of the magnet in the bipolar configuration in which the patient is positioned for imaging. In one embodiment considered here, , the gap 116 illustrated in FIG. 1 is 28 cm.

[0034] The gradient coil assembly 104 is configured to provide spatial encoding of the imaging data. It contains the coils necessary to apply a weak variable magnetic field in addition to the magnetic field of the main electromagnet 102. The gradient coil assembly 104 may be a continuous cylindrical assembly and is shown in FIG. It may be a split gradient coil assembly as shown, or it may be It may also have other configurations as may be required for the particular MRI configuration being used.

[0035] The RF coil system 106 excites the spins of hydrogen protons in the body of the patient 110, The RF coil system is responsible for receiving the signals subsequently emitted from the subject 110. The system 106 includes an RF transmitter portion and an RF receiver portion. Alternatively, the device may include a single volume coil that performs both the RF receiving and the RF receiving functions. The RF coil system 106 has a transmitting function and a receiving function, and is configured with a volume coil and a surface coil. Alternatively, both the transmit and receive functions may be integrated into the surface coil. The information may be provided in the form of a single line.

[0036] The magnetic resonance imaging system includes: and a control system configured to perform, including image reconstruction. The control system includes a number of subsystems, such as the gradient coil assembly 104, the RF Coil systems 106, subsystems that control the operation of portions of these systems, and and a sub-subsystem for processing data received from the RF coil system 106 and performing image reconstruction. For example, an interventional device (e.g., a radiation therapy device) may include a system. When an additional control system function is included, the additional control system function is considered to be included when the additional control system function is integrated into the MRI100. good.

[0037] FIG. 2 is a simplified cross-section of the main electromagnet 102 shown in FIG. 1, including the gap 116. The gradient coil 104 and the RF coil 106 are not shown in this figure. FIG. 2 shows all four cross sections of the main electromagnet 102. The cross-section of FIG. 1 takes the bore 200 and imaging area or field of view (FOV) 202 of the MRI 100. are arranged in a surrounding manner.

[0038] FIG. 2 illustrates an important concept that will be referred to specifically in this disclosure as the "magnet envelope." The term "magnet envelope" as used herein refers to A in FIG. This term can be explained by referring to the letters A, B, C and D. The outer boundary of the conductor used to make the magnet move is rectangular. If not, the magnet envelope is the smallest rectangle (or or in the case of irregular shapes, a closely fitting convex polygon) For example, a conductor is used near the corner of the electromagnet 102 marked with the reference symbol "C." However, the magnet envelope does not follow the conductor boundary exactly, but it does follow the corner "C" The magnet envelope is shown in two-dimensional cross section in the figure, The magnet envelope is actually the entire three-dimensional volume that corresponds to the cross section (i.e., roughly speaking, A vertical axis defined by sweeping a cross section at a constant radius around the Z axis of a solenoid magnet. It should be understood that this encompasses the body region.

[0039] In a magnet with a gap, as shown in Figure 2, "inside the magnet envelope" is the magnet The inside of the magnet envelope formed by the conductors contained in both halves In the example shown in FIG. 2, the magnet envelope is the area defined by points A, B, C, and D. , and the area defined by points E, G, F, and H, but within the magnet gap 116 It should be understood that the gap does not include the magnet element. The envelope is defined by E, B, F and D.

[0040] FIG. 3 focuses on the right half of the electromagnet 102 shown in FIGS. 1 and 2, and in particular The figure shows the upper right part of the quadrant of the magnet. In this figure, the X-axis is aligned along the Z-axis of the magnet. The Y axis is the distance from the center field of view (FOV) and the Y axis is the diameter of the solenoid magnet from the Z axis. An additional dimension is added to the example to indicate directional distance.

[0041] In the example configuration of FIG. 3, the conductors 302 are shown as shaded areas and the ferromagnetic material 304 is shown as black. The absence of conductive or ferromagnetic material is indicated by the open area 306. vinegar.

[0042] An electromagnet is, of course, formed from a conductor such as a loop of copper wire. In this case, the term "conductor" refers to any electrically conductive ring, coil, or main magnet of an electromagnet. Fields refer to any structure that is used to generate a field. In this case, it means multiple conductors (e.g., multiple separate coils or multiple wire bundles). Not only is it intended, but multiple "conductors" are technically one continuous conductor, even though For example, this also refers to a structure comprising a plurality of conductive rings, turns, or other structures. This is also fine.

[0043] In one particular advantageous embodiment of the present disclosure, the ferromagnetic material is An example of this is shown in FIG. 3 as ferromagnetic material 304. Iron, alloy steel and martensitic stainless steels (but not austenitic stainless steels, which have low magnetic permeability). For example, ferromagnetic materials with an initial relative permeability of more than 20 may be used. Martensitic and ferritic stainless steels are available. Ferromagnetic materials with low initial relative permeability, such as stainless steel, are also possible, but non-stainless steels (e.g. It is preferable to use a material with a high initial relative permeability, such as SAE 1006 steel.

[0044] FIG. 3 is a diagram illustrating one exemplary embodiment that includes ferromagnetic material within the envelope of an electromagnet. In this particular magnet configuration, the magnets are referenced L1, L2, L3, L4, L5, and L6 on the top and bottom of Figure 3. The magnet contains six layers, each labeled with a number. A "layer" is located at a given radial distance from the magnet's axis. In the example of FIG. 3, the layer L Each of L1 to L6 is configured to have a height of 4 cm. Therefore, in this example, Layers L1, L2, L4, L5 and L6 are 4cm x 4cm conductors in roughly cylindrical shape. At L4, a generally cylindrical member is wound around the 4 cm thick A ferromagnetic material (e.g., steel) is provided (the ferromagnetic material is not shown in the lower half of FIG. 3). do not have).

[0045] While the example of FIG. 3 utilizes relatively large, evenly spaced conductors, the Beneficial techniques can also be used in electromagnet configurations that include "bundled" conductors. For example, The ferromagnetic material in the envelope can, for example, hold a bundle of small conductors together. 0, which are arranged at specific positions within the magnet to generate the desired magnetic field. It may be useful to have an electromagnet composed of

[0046] This disclosure does not consider that multiple layers of an electromagnet configuration similar to FIG. 3 need not all be the same height. The height of the ferromagnetic material layer does not have to be the same as that of any of the conductor layers. For example, In one embodiment, the conductor layer is 4 cm high and the ferromagnetic layer is only 2 cm high. It may be that there is no such thing.

[0047] This disclosure provides many different configurations of ferromagnetic material within the electromagnet envelope. The example of FIG. 3 includes a single layer of ferromagnetic material formed as a complete layer. The electromagnet may similarly be constructed having multiple layers of ferromagnetic material; Alternatively, the layer of ferromagnetic material may be partial. In the above example, a cylindrical ferromagnetic Although we consider a layer of material, the ferromagnetic material within the electromagnet envelope does not need to have a cylindrical shape. Furthermore, a portion of the ferromagnetic element is disposed within the envelope, and the portion If the structure extends outside the envelope, then such a structure is referred to as "located within the envelope." It is considered that the composition of the "ferromagnetic material" is satisfied. In other words, the ferromagnetic layer 3 shown in FIG. The material extends outward along the Z axis of the magnet, past the envelope defined by the conductor. In this specification, such an embodiment is also referred to as having ferromagnetic material "within the envelope" of the electromagnet. It is understood that this has a fee.

[0048] In particular, the present disclosure relates to a magnet configuration without a yoke and a magnet with no magnetic flux return. The magnet configuration described in this specification is a strong magnet within the electromagnetic envelope. A magnet configuration having a magnetic material can be distinguished from a flux return and a yoke. In the case of a magnet with a magnetic field (as shown in Figure 2), the flux return or yoke is the " Within the envelope (the ranges indicated by the reference symbols A, B, C, D, E, F, G, and H above) Rather, it is disposed within the bore 200 of the magnet. Similarly, the flux return or yoke The dipole magnet configurations typically utilized are distinct from those of the present disclosure.

[0049] The present disclosure further provides magnets in which the main magnetic field is primarily generated by one or more permanent magnets. Such a system seems to have ferromagnetic material within the magnet envelope. It may be possible, but it is separate from the technology disclosed in this specification. In relation to electromagnets, "inside the envelope" refers to the magnetic field used to generate the main magnetic field of the electromagnet. The term is defined as within the envelope of the conductor in which the

[0050] In one example configuration shown in FIG. 3, the amount of ferromagnetic material is about 1 / 6 of the total volume of the electromagnet, and It can be seen that the volume of the conductor is about 1 / 5 of the volume of the conductor. The total volume of the ferromagnetic material may be reduced to about 1 / 10 of the volume of the conductor. In another embodiment, the volume of the ferromagnetic material is only 1 / 20 of the volume of the conductor. In particular, the volume and composition of the ferromagnetic material may vary widely, Com sol MultiPhysics or Faraday (Integrated E (manufactured by Infosys Engineering Solutions, Inc.) Model a typical magnet configuration and add power (e.g., to drive the negative current loop) Sufficient magnetizing current flows in the ferromagnetic material to improve the homogeneity of the main magnetic field without the need for This may be determined by coming up with configurations that arise.

[0051] The electromagnet configuration proposed herein does not require additional ferromagnetic material to be placed outside the electromagnet envelope. Note that this additional ferromagnetic material is used to reduce the fringe fields of the electromagnet. An example of such a fringe field reducing material 402 is shown in FIG. For example, this additional ferromagnetic material 402 may be a steel structure with an L-shaped cross section and a thickness of 1-2 cm. Such additional passive shielding may be included in the construction. When modeling the magnet as described above, the ferromagnetic material within the electromagnet envelope and Consider that along with the conductor.

[0052] Interventional applications where ferromagnetic materials must be placed within or near a magnet If electromagnets are utilized, these should be considered when configuring and modeling for optimal uniformity. Note that other materials should be considered as well. Figure 5 shows the interfacial Specifically, an MRI-guided radiation therapy system is illustrated. In addition to the electromagnet 102, FIG. 5 illustrates a magnetic field shielding a portion of the linear accelerator 508 from the main magnetic field of the electromagnet. 5 shows a gantry 502 on which a magnetic shield shell 504 is mounted to protect the As shown, a portion 508 of the linear accelerator is connected using an RF waveguide 506. According to this configuration example, the magnetic field shield shell 504 may be an electromagnet. Along with the ferromagnetic material and conductors contained within the envelope of the magnet, there are other factors to consider when designing an electromagnet. It contains a large amount of ferromagnetic material to be placed.

[0053] One embodiment of the present disclosure thus implemented is a normal conducting solenoid for whole body MRI having conductors. a ferromagnetic material disposed within the envelope of the electromagnet; A magnetic resonance imaging (MRI) system. The electromagnet may be gapped. In another embodiment, the volume of the ferromagnetic material is the volume of the conductor. In some embodiments, the conductor volume is at least 1 / 6 of the volume of the conductor, or at least 1 / 20 of the volume of the conductor. In this configuration, the electromagnet may include multiple cylindrical layers, and the ferromagnetic material is Alternatively, the ferromagnetic material may comprise one of the layers of the circular pattern. It may include a portion of one of the cylindrical layers. The elastic material may include more than one of the cylindrical layers, or The multi-layer structure may include multiple portions of multiple layers such as:

[0054] Many existing magnet configurations, especially solenoid magnet configurations with gaps, have problems with the magnetic field. To achieve the desired uniformity, current must be applied in both positive and negative directions in the electromagnets. As used herein, a "positive" current flow is defined as a current flow that is positive to the magnet's main magnetic field Bo. (e.g., positive flow direction 118 and main magnetic field 122 in FIG. 1 ). ). A "negative" current flow is one that opposes the magnet's main magnetic field Bo (for example, (See, for example, negative flow direction 120 in FIG. 1). These circumferential flow patterns This can be easily understood if we consider the right-hand rule of reason.

[0055] In electromagnets that utilize bundled conductors to generate the main magnetic field, certain bundles have a positive current flow. In the lower part of Fig. 3, the current flow is positive, while in the other bundles it is negative. For the electromagnet configurations shown in the figures, many alternatives to the S-bends of the integrated conductors are available. can have a U-shaped bend so that the current flows in the negative direction.

[0056] Using techniques of the present disclosure, for example, magnet configurations that include ferromagnetic material within a magnet envelope, , magnet configurations with only positive current flow are possible, and magnet configurations with gaps Even with this, a uniform magnetic field can be generated at a satisfactory level.

[0057] In some embodiments of the present disclosure, the magnetic resonance imaging system thus includes a conductor A normal conducting solenoid-shaped electromagnet for body MRI and a strong magnet installed inside the electromagnet envelope and a magnetic material. The system may be of the gap type. Assume that the electromagnet is configured to generate current flow in only one circumferential direction within the magnet. For example, each of the bundled conductors driving the main magnetic field may have a positive current direction. Alternatively, in the case of a configuration other than bundled, each conductor (e.g., The conductor (or conductors) is configured, bent or shaped to generate only positive flow current.

[0058] In other embodiments, the electromagnet is configured to have a negative current flow of less than 5% or less than 10%. For example, in the embodiment of FIG. 3, less than 5% or 10% of the conductors may be % may be configured or formed to generate a negative current flow. In other words, less than 5% or even 10% of the current loops have negative current flow. (For example, one loop is one turn that surrounds the outer circumference of the magnet.) (representing a department).

[0059] Reducing or eliminating negative current flow reduces power supply requirements for certain magnet configurations. A specific embodiment of such a system is described below, and the power supply Examples of sizes are given below. These specific system configurations and associated power supply sizes are The sizes are merely examples and other configurations and power supply sizes or size ranges are contemplated. I want to be understood.

[0060] A particular embodiment of the magnetic resonance imaging system described herein is a whole-body MRI system having conductors. A normally conducting solenoid-shaped electromagnet and a gap are provided in the electromagnet envelope. The conductor may be made of copper. In these areas, the conductor is directly cooled (i.e., coolant flows through the center of the conductor) and the magnetic field strength is low. The power source must be configured to be less than 30 kW or less than 45 kW, with a minimum of 0.12 Tesla. In another embodiment, the magnetic field strength is at least 0.2 Tesla and the power source is 100 It is possible to configure it to be less than 100 kW or less than 145 kW. has a magnetic field strength of at least 0.3 Tesla and a power supply of less than 210 kW or less than 300 kW It is possible to configure the conductor to be indirectly cooled (e.g., a coolant is introduced into the conductor). In some embodiments, the conductor is cooled naturally by the surrounding environment. Such electromagnets have a magnetic field strength of at least 0.12 Tesla and a power supply of less than 35 kW or In another embodiment, the magnetic field strength is less than 50 kW. The power supply must be configured to be less than 105kW or less than 150kW. In another embodiment, the magnetic field strength is at least 0.3 Tesla and the power source is 2 It can be configured to be less than 30 kW or less than 330 kW.

[0061] Another embodiment of the magnetic resonance imaging system described herein is for a whole body MRI having a conductor. A normal conducting solenoid-shaped electromagnet and a gap are provided in the electromagnet envelope. The conductor may be made of aluminum. In some embodiments, the conductor is directly cooled (e.g., coolant flows through the center of the conductor) and the magnetic field strength is The temperature must be at least 0.12 Tesla and the power source must be less than 45 kW or less than 65 kW. In another embodiment, the magnetic field strength is at least 0.2 Tesla and the power supply can be configured to be less than 155 kW or less than 220 kW. In an embodiment, the magnetic field strength is at least 0.3 Tesla and the power supply is less than 335 kW or 480 It is possible to configure it to be less than kW. The conductor is indirectly cooled (e.g. Cooling material flows around the conductor, or the conductor is naturally cooled by the surrounding environment. So, such an electromagnet would have a magnetic field strength of at least 0.12 Tesla and a power supply of less than 50 kW. In another embodiment, the magnetic field strength may be configured to be less than 70 kW. The power source must be less than 170kW or less than 245kW. In yet another embodiment, the magnetic field strength is at least 0.3 Tesla and The power supply can be configured to be less than 365 kW or less than 520 kW.

[0062] As described above, the technology according to the present disclosure can reduce the required power, resulting in By dividing a solenoid-shaped electromagnet with a gap into two halves, the force acting between the two halves is reduced. In the existing technology, a solenoid-shaped electromagnet with a gap is The two components are pulled together with great force, but are separated by large At the same time, a small fixed structure is required to prevent relative displacements that may affect the uniformity of the magnetic field. Movement must be avoided.

[0063] An example of a large-scale fixation structure is shown in FIG. 1 as buttress 114. The bench must typically be made of a strong material, usually a metallic material such as steel or aluminum. However, according to the technology disclosed herein, a normal conducting solenoid for whole-body MRI having a conductor is a gap-shaped electromagnet and a ferromagnetic material disposed within the envelope of the electromagnet; It is possible to realize a magnetic resonance imaging system equipped with the above-mentioned. The portions are spaced apart by a securing structure, and in some embodiments the securing structure is substantially It may be non-metallic. "Substantially" non-metallic means that the two parts that make up the magnet are "It is understood to mean a fixed structure that primarily utilizes non-metallic materials to resist the forces that Insofar as such structures contain metallic materials but do not primarily bear the load, Such structures are intended to be included within the scope of the phrase "substantially non-metallic."

[0064] In certain embodiments, the anchoring structures presented herein are made of carbon fiber or May contain zero carbon fiber.

[0065] When the above-mentioned technology is combined with a radiotherapy device, the combined system can be used for radiotherapy. The device may be configured to be directed to deliver treatment through the fixation structure. For example, the fixed structure is placed between the two parts of the magnet and has a uniform thickness of 0.5 cm. The cylindrical member may be made of a single carbon fiber, and the thermal expansion coefficient may be substantially zero. , providing minimal and uniform attenuation to the radiation therapy beam.

[0066] In yet another embodiment, the stationary structure may be a cylindrical member or a continuous former; Not only does it extend between the two parts that make up the magnet, but also into the electromagnet assembly itself. It extends (eg, as a former disposed between a number of layered conductors).

[0067] The techniques disclosed herein can reduce electromagnet current requirements and heating; In addition, it reduces the forces exerted on the magnet conductors and the structures that support them. These techniques therefore allow certain types of beneficial magnet configurations and construction methods to be implemented. For example, in one particular embodiment, the at least 0.05 test Magnetic resonance imaging system with normal conducting solenoid-shaped magnets for whole-body MRI with a magnetic field strength of 1000 nm The system may include conductors that generate the main magnetic field of the electromagnet. Instead, a layered conductor may be produced.

[0068] Cylindrical MRI systems typically use bundled conductors (i.e., multiple conductors bundled together). The main magnetic field is generated using a magnetic field generator (which is arranged at a specific number of separate positions) as a feature of the present disclosure. In certain embodiments, more distributed conductors, e.g., distributed across multiple layers, may be used. An example of such a layered conductor configuration is shown in Figure 3. This layered configuration produces a highly uniform magnetic field. This makes it easier to realize a new and advantageous manufacturing method, and therefore the main In this disclosure, the "main magnetic field is not generated by a bundle of conductors." When describing a "more distributed" configuration, this is meant to indicate that the main magnetic field is entirely or primarily a more distributed configuration. conductor configuration (e.g., similar to that described with reference to FIG. 3). Nonetheless, the present disclosure provides a method for utilizing a small number of bundled conductors with these configurations. For this reason, the main magnetic field is not generated by a bundle of conductors. In the specification, the minimum use of bundled objects is considered. For example, However, its contribution to the generation of the main magnetic field shall not exceed 10%.

[0069] When this disclosure refers to generating a main magnetic field using conductors arranged in "layers," In this case, for example, a looped conductor or coil is generally cylindrical at the radial distance of the electromagnet. are arranged in a circular pattern over most of the length of the electromagnet (or , which means that the magnet extends over most of the half-length of the electromagnet. FIG. 1 shows an example of a layered configuration of a solenoid magnet having a loop. The conductor, which is constructed in several layers, extends about one meter along the Z axis of the magnet and is connected to the imaging frame. From a point about 0.2 m away from the center of the imaging field to a point about 1.2 m away from the center of the imaging field Extend or cross to a point.

[0070] The main magnetic field may be generated by multiple layered conductors, as shown in FIG. The electromagnet of the configuration is similarly shown in FIG. 3 and described above. The envelope may include a ferromagnetic material.

[0071] FIG. 6 shows the configuration example of FIG. 3, with a view from the opposite side. The figure shows five separate layered conductors for generating the ferromagnetic cylindrical member. The present disclosure contemplates the use of a variety of numbers of layers, and The number may depend, for example, on the size of the particular conductor selected. In the example of FIG. Use a relatively large conductor (e.g., 4 cm x 4 cm with a conductor hole for direct cooling). (having a).

[0072] In another embodiment, a conductor of 2 cm by 2 cm may be used. Generates normal conducting solenoid-shaped electromagnets and electromagnet main magnetic fields for 0.05 Tesla whole-body MRI In one specific embodiment of the conductor, the main magnetic field is generated by a layered conductor, and the conductor has a cross-sectional area of ​​0.50 cm 2 Greater than or equal to 0.75 cm 2 Greater than.

[0073] In some embodiments, some portions of the conductors have a smaller cross-sectional area than other portions of the conductors. For example, a layer of relatively small conductors may have a cross-sectional area approximately half that of a layer of relatively large conductors. (For example, the conductors on one layer may have a cross section of 40 mm x 40 mm and the conductors on another layer may (The body may be 20 mm by 20 mm in cross section.) In some embodiments, the relatively small The conductor layer is disposed on or adjacent to the radially outer layer, or or in the vicinity of or adjacent to a ferromagnetic layer (for example, L3 shown in FIG. 6). It may be placed in the

[0074] Layered configurations utilizing the techniques of the present disclosure allow for improved performance in bundled configurations and configurations with high current requirements. This may eliminate the need for the large, sturdy metal formers that are typically used. In examples, the conductors of the proposed configurations are made of fiberglass or plastic. The coil may be supported by a relatively low strength material, such as a cylindrical former made of The conductors are wound on cylindrical fibreglass formers, 1mm thick, between the layers. The layered conductors and formers may then be supported by epoxy or other insulating material. By combining the materials, they may be made into a single rigid body.

[0075] FIG. 7A shows a cross-section of one particular embodiment, in which conductor layers L1, L2, L4, L5, L6 and the ferromagnetic layer L3 are separated by a former 702, which is a glass The electromagnet may be constructed of a non-metallic material such as a reinforced polymer. Side cheeks 704 made of similar non-metallic material and optionally stronger metallic material 7 shows an embodiment having an outer former 706 formed from a material such as aluminum.

[0076] In one particular embodiment, the magnetic field strength is at least 0.05 Tesla for whole body MRI. A conductive solenoidal electromagnet may include a conductor that generates a main magnetic field of the electromagnet, The field is generated by a layered conductor, and the electromagnet is wound around a non-metallic former, e.g., fiberglass. One embodiment uses a small number of coils separated by non-metallic coil formers to support the conductors. At least two solenoidal conductor layers. Another embodiment has fewer than 10 conductor layers. In yet another embodiment, the conductor layer and the non-metallic former may be, for example, an epoxy. The plates may be assembled by fastening them together with a screw to form a rigid body. The rigid body may further include at least a portion of a gradient coil. For example, It may incorporate only slice selection coils, or alternatively, gradient coils. The entire magnet may be epoxy bonded to the main magnet to form a unitary rigid body.

[0077] FIG. 7A is a diagram illustrating an example of a conductor 708 having a core 710. The conductor 708 is generally positive. It has a rectangular cross section, and the core 710 is cylindrical and hollow, allowing it to be used for direct cooling. (eg, by flowing water or a coolant within the core 710).

[0078] FIG. 7B shows an example of an electromagnet with an indirect cooling system achieved by serpentine coolant channels. FIG. 1 is a diagram showing an indirect cooling system that, in some embodiments, provides sufficient cooling for the electromagnets. Therefore, some or all of the conductors of the electromagnet may be the same as those shown in FIG. 7A. Rather than having a hollow core 710 as in the direct cooling example, the can.

[0079] The present disclosure provides a variety of configurations, such as, for example, saddle-shaped circular loops, spiral loops, serpentine shapes, etc. As shown in Figure 7B, an indirect cooling system with a serpentine cooling channel has been proposed. The channel 720 includes one or more straight sections 722 and one or more curved sections 724. which when combined form an “S-shaped” or “serpentine” channel 720 In some embodiments, the meandering channel 720 is formed by one or more of a conductive or ferromagnetic layer. It may be adjacent to (or wrapped around) the number, which allows for indirect FIG. 7C shows an example of an indirect cooling system similar to that shown in FIG. 7B. However, the meandering channels are interspersed between layers of conductors and / or ferromagnetic materials.

[0080] The serpentine channel 720 has an inlet and an outlet (e.g., In some embodiments, the inlet and / or outlet may be configured to accommodate cooling. For example, the electromagnet may be located at an end 730 of the electromagnet where it is more accessible for communication with the electromagnet. For example, the inlet and outlet may be located at the patient end or the service end of the electromagnet. It may be possible to place it there.

[0081] When this disclosure refers to a solenoidal electromagnet or a solenoidal conductor layer within an electromagnet, the conductor There are some deviations from a perfect solenoid (i.e., a coil wound evenly in a spiral shape). For example, a single layer conductor may have an S-shaped bend. (Illustrated as element 602 in FIG. 6).

[0082] The S-shaped bend configuration is an alternative to the helical configuration. These are different manufacturing processes. In addition to being a process, the software used to model the current loop purely If we simplify it as a simple ring current (in this case the S-shaped bend configuration is a spiral) This provides a better fit to the model than a conventional configuration, making it more effective when designing magnets. It can be modeled.

[0083] In this specification, when we say "S-shaped bend," we mean the "S" extended as shown in the figure. The shape may be such that the transition to the subsequent loop is gradual or abrupt (a 90 degree turn). This also includes the possibility that the current flow in the subsequent loops continues in the same circumferential direction. The S-shaped bend is distinct from the helical configuration and is distinct from the U-shaped bend. In the U-shape, the current flow in the subsequent loops is in the opposite direction.

[0084] As mentioned above, certain electromagnet configurations have a negative current (i.e., a magnetic field that counteracts the direction of the main magnetic field). When such a negative current is required, the coil of the present disclosure may include a This can be achieved by using a U-shaped bend. However, as mentioned above, The flow can be achieved using the techniques of the present disclosure, which include providing a ferromagnetic material within the envelope of an electromagnet. It can be said that this occurrence has been avoided.

[0085] In a particular embodiment, the conductors are arranged to traverse the layers in a direction parallel to the axis of the solenoid electromagnet. Such an arrangement is shown in FIG. The modeling and configuration of the layer dictates that no current loop is needed at that particular axial location. For other illustrations, such a position may be used in the configuration of FIG. In the example shown as element 306 .

[0086] In one specific embodiment, the magnetic field strength is at least 0.05 Tesla for whole body MRI. A normal conducting solenoid electromagnet may have a conductor that generates a main magnetic field of an electromagnetic field. The magnetic field is generated by layered conductors, one of which is parallel to the axis of the solenoid electromagnet. At least one layer having a portion extending transversely in the direction of the wire, the one conductor having a cross-sectional area of ​​0. .50cm 2 Greater than or equal to 0.75 cm 2 It may be greater than .

[0087] In some embodiments, the layered conductor is wound in a spiral having a first spiral slope. a first layer being a conductor with a helical shape adjacent to the first layer and having a second helical slope; and a second layer including a conductor wound around the first spiral. In other words, in certain embodiments, the spiral is wound with a rightward inclination. The layer may be a conductor attached to the substrate, and a layer (or layers) may be placed immediately inside or outside the layer. The adjacent layers at the next smaller or next larger radius are inclined to the left and spiral It is a conductor wound in a rectangular shape.

[0088] In another embodiment similarly configured to facilitate generating a uniform magnetic field, the layered conductors include: a first wound conductor layer having a first S-shaped bend bent in a first direction; a second wrapped conductor adjacent to the first wrapped conductor and having a second S-shaped bend bent in a second direction; The first S-shaped bend and the second S-shaped bend may be overlapped. The second direction is opposite to the first direction. An example of such a configuration is shown at the bottom of FIG. The outer layer 808 has an S-shaped bend that is bent in one direction, and the adjacent layer 810 has S-shaped bends that bend in opposite directions, and the S-shaped bends of each layer are at positions 812 Another configuration is shown at the top of FIG. 8A. The S-shaped bends overlap. However, it is not bent in the opposite direction.

[0089] FIG. 8B illustrates an electrophoretic diagram of a radially bent S-shaped bend in accordance with certain embodiments of the present disclosure. FIG. 1 is a simplified diagram showing an example of the structure of a portion of a magnet. The conductive layers are joined (e.g., generally radially) by one or more S-shaped bends 826. An example of such a configuration is shown in FIG. Two conductor layers are shown, with a first wrapped conductor layer 820 being bent by an S-shaped bend 826. The wire is then connected to the second wound conductor layer 822. Also shown in FIG. 824. In some embodiments, one or both of the adjacent layers may be helical (e.g., excluding axially bent S-shaped bends); or Alternatively, the helical pitch may be replaced by an axially bent S-shaped bend.

[0090] FIG. 8C is a simplified diagram illustrating an example of an electromagnet configuration according to certain aspects of the present disclosure. This example configuration includes an electromagnet configuration having a gap, and a circular magnet disposed in the gap. These cylindrical members are components of a linear accelerator for radiation therapy applications. In a specific embodiment, the magnet may be split into two halves. The portions (830, 832) are radial connection portions 834 (e.g. , S-shaped bends) may be "rotated" so that they are not at the same azimuth angle. As a result, the residual harmonic function generated by the connection part, which is the radial S-shaped bend, is small. This may have the beneficial effect of reducing the size of the magnet. The two halves may be rotated approximately 180 degrees relative to each other. However, other rotation angles are possible, for example, 30 degrees, 45 degrees, 60 degrees, 90 degrees, 135 degrees, 150 degrees. , 165 degrees, etc. One of the two halves of the magnet is called the "patient end." (where the patient enters the bore 200 of the MRI system), and the other is the “service In one embodiment, the patient-side radial connection portion 834 may be referred to as the "patient-side" radial connection portion 834. It may be located at the bottom (i.e., the lowest part of the patient-side magnet portion 830) and the service provider may provide The radial connection portion 836 of the supply side is at the top (i.e., the magnet portion 832 of the service side). In another embodiment, the angle between the two halves of the magnet may be The total rotation may be different (for example, relative to the vertical, the total rotation may be 30 degrees, 45 degrees, 60 degrees, 9 0 degrees, 135 degrees, 150 degrees, 165 degrees, so that the radial connection is at the top and and at the bottom), whereas the radial connection between the two halves of the magnet is The state where they are separated by approximately 180 degrees is maintained.

[0091] In the magnet configuration example of the present disclosure, multiple conductor layers (e.g., L1, L2, L4, L5 in FIG. 3) and L6) may be connected to form a substantially single current path. The elements may be configured to operate with a single supply current. The interlayer connections are The layers are shaped so that they contribute positively to the generation of the main magnetic field by being positive in each layer. In the case of a magnet with a gap, the two halves of the magnet are connected in series. Since the 100V supply is connected in series, it can still operate with a single supply current (otherwise it would be parallel). (The current flow can be assumed to be the same for all three columns.) In this useful configuration, It is often necessary to have different currents for each bundle (and negative currents for one or more bundles). Simplifies the power supply used, as opposed to the usual bundled magnet configurations (which often require It is possible.

[0092] FIG. 9 does not employ layered conductors, but similarly uses a more precise arrangement of conductors to generate the main magnetic field. FIG. 1 illustrates another electromagnet configuration in which the conductors are distributed over the For example, at least 40%, 50%, 60% or 70% of the magnet envelope may be covered. In the particular embodiment shown in FIG. 9, the conductor covers more than 50% of the magnet envelope. The main magnetic field is generated using a bundle of conductors 902. Although many electromagnet configurations that use very small conductors to generate the main magnetic field can be used, in this disclosure We also propose to use a larger bundle of conductors. In a specific example, each conductor 904 has a cross section of 1 cm by 1 cm.

[0093] This type of configuration embodiment also includes the use of ferromagnetic material within the magnet envelope, as previously described. One example is shown as ferromagnetic material 906 in FIG. It is possible to configure an electromagnet so that the current flows in only one circumferential direction within the magnet. Each flux driving a magnetic field may have a positive current direction. The stone may be configured to have less than 5% or less than 10% negative current flow. In one embodiment, the conductor bundle is formed by conductors that cross each other in a direction parallel to the axis of the electromagnet. are connected together to form a single current path, so that the electromagnets are powered by a single supply current. may be provided.

[0094] Electromagnets, especially those used in magnetic resonance imaging, produce very uniform and stable magnetic fields. Such stability results in very stable voltage and current outputs. This is achieved by utilizing advanced DC power supplies that maintain a constant current (e.g., fluctuations of only a few ppm). However, the technology disclosed herein makes it possible to realize such a complex power supply structure. These techniques can achieve a uniform and stable magnetic field without the need for a magnet. , a conventional solenoidal (without gap) magnet, a solenoidal system with gap The present invention is applicable to various magnet configurations such as magnets, magnetic systems, and bipolar magnets.

[0095] When this disclosure refers to electromagnets for magnetic resonance imaging, such magnets and corresponding power supplies include: The uniformity and stability (e.g., about several ppm) of the imaging magnetic field required for MR imaging etc. can be obtained. As used herein, the term "power supply" includes rectified necessary for the electromagnet, including any associated electronics for purposes of filtering, control, etc. It is intended to include electronic devices that perform the function of supplying power. The may exist as a single unit or may be distributed across multiple different locations or modules. In addition, the power supply may be a single unit that supplies a single current. or may be configured to provide multiple, possibly different, currents. It is understood herein that the power supply may be multi-channel.

[0096] Power supplies for MRI systems are typically designed to provide DC current that varies only on the order of a few ppm. However, the technology disclosed herein is not required for a power supply with a stability of, for example, only 1 per milliad. A stable magnetic field can be achieved with a uniform magnetic field and with a high degree of stability. , which relates to the DC current ripple that exists after rectification at the original AC frequency and its harmonics. For example, embodiments of the present disclosure may be used with frequencies above 180 Hz or below 60 Use a power source with a current fluctuation of at least 1 per milliad at frequencies above 0 Hz. In other embodiments, at frequencies above 180 Hz or above 600 Hz. Even a power supply with a current fluctuation at the above frequencies of at least 1 part per mille may be utilized.

[0097] Such power supplies have relatively large current fluctuations and are suitable for use with the various electromagnet configurations disclosed herein. The complex impedance of the wound metallic conductor in the In one embodiment described below, an example of an electromagnet is a 60 Filtering current fluctuations of 15 per milliads above 0 Hz down to -90 dB In this way, the embodiment of the present disclosure realizes a filtering effect realized by the normal conducting electromagnet itself. This may include a magnetic resonance imaging system that does not have a current filter separate from the imaging function. In other words, such a system requires additional components (e.g. The figures do not include the additional capacitance (for example, an inductor).

[0098] Another embodiment includes a current filter, the inductance of such a filter being: For example, it may be limited to less than 5 mH, 2 mH, or 1 mH. One specific embodiment of the imaging system is a whole-body MR system with a magnetic field strength of at least 0.05 Tesla. A normal conducting magnet for I and a current fluctuation of at least 1 per milliad at frequencies of 180 Hz or more. The normal conducting electromagnet itself is equipped with a power source that supplies power to the normal conducting electromagnet. The current filter may not be separate from the inductor. The input may include a current filter with a capacitance of less than 2mH.

[0099] In accordance with certain embodiments of the technology described herein, a single channel power supply is utilized. For example, the magnet may be provided with a ferromagnetic material within the magnet envelope. In the particular electromagnet configuration described below, one current may be provided. The magnet configuration may, for example, consist of bundled conductors and / or This allows multiple power channels to be optimized so that no negative or positive current is required. Simple single-channel design that does not require a complex control system to synchronize the channels with each other. In addition, the current fluctuations at low frequencies of single-channel power supplies are ,Compared to the variability of the multichannel power supply, the MRI control system, which,causes such variability, For example, the MRI spectrometer can be used to measure the intensity of the main magnetic field. This may compensate for low frequency drifts in current or voltage.

[0100] In a particular embodiment, these power sources are solenoids with gaps according to the examples given above. It can be used in combination with a direct-cooled aluminum magnet configuration. In embodiments utilizing rubber conductors, the electromagnet has a magnetic field strength of at least 0.12 Tesla. and the power supply may be configured to provide up to 45 kW of power. The construction may utilize a power source of 155 kW or less and a magnetic field strength of at least 0.2 Tesla. Other configurations as taught or specifically described herein are contemplated.

[0101] Even single channel power supplies for MRI typically minimize current and voltage fluctuations. However, the present disclosure provides a power supply that does not include active current control. Consider the use of a current feedback loop.

[0102] The embodiments of the present disclosure add a simple filter, for example an LC filter, to reduce voltage fluctuations. In one embodiment, similar to the configuration described above, a 28 cm gap is used. and configured to perform whole-body MRI, the magnetic field strength of which is at least 0.12 Tesla. Consider a solenoidal electromagnet, which is a slab. The electromagnet contains a ferromagnetic material within the magnet envelope. The conductor is made of aluminum and is directly cooled. An example of a filter in this case is shown in Figure 10. In this example shown in Figure 10, the resistance is 40 mΩ and the inductor The inductance of the electromagnet is 40 mH. The power supply used is 40 V and 1000 It can be configured to provide a 1 A output with ripple of 10 kHz at 600 Hz and 57.6 kHz. In this example, Lin=1mH, Rin=1mΩ, Ct A filter with Rt = 50mF and Rt = 0.1mΩ may be used. The filter characteristics may be determined based on the following formula:

[0103]

number

[0104] These equations represent the transfer function (dynamic response) of the system. The Bode plot of the gain is , which may show the gain response as a function of frequency (high frequency components are effectively filtered out). Such a diagram (or equivalently a transfer function calculation) is useful for determining the low-frequency The filter is designed to suppress the magnitude of the ripple at undesirable frequencies higher than the wavenumber. It can be a means to design.

[0105] In another embodiment, a system is provided that includes a power supply that is at least partially adapted to limit power supply fluctuations. In addition to or in addition to the filters mentioned above, one or more batteries may be used. Such a battery may be used in place of the filter described above. The electromagnet may be connected to a battery and may be substantially powered by the battery. The system may be configured so that the battery can be recharged by a power source.

[0106] In electromagnets, the power fluctuations that can occur due to the power source charging the batteries are In such an embodiment, the electromagnetic The battery responsible for powering the stone can avoid charging while powering the magnet. If the battery powering the electromagnet needs to be charged, the power supply for the electromagnet must be You can switch to another battery that is already fully charged. The stem is a system that generates multiple electric currents while the normal conducting electromagnet is connected to one of the multiple batteries. The battery may be configured to allow the power source to charge another battery in the battery.

[0107] Another example of an embodiment including multiple batteries is shown in FIG. 11, which utilizes at least three batteries. As shown in the upper part of Figure 11, a switch is opened and closed to supply power to the electromagnet from one battery. The first battery is turned on (but not charged at the same time) while the remaining batteries are charged. When it needs to be charged, it is powered by another battery that is already disconnected from the power source. The switch position may be changed to switch the electromagnet to receive the The switch connected to charge the second battery is connected to a switch between the second battery and the electromagnet. before closing it to power the magnet. Such a system would have two batteries that are not charging and are not subject to power fluctuations. In other words, the transition between the The system may include at least three batteries, and the resistive electromagnet is connected to the first battery. The second battery may be configured to be charged while the battery is connected to the The system further ensures that the normal conducting magnet connection is switched to the first non-charging magnet when switching this connection. The battery may be configured to switch between three batteries.

[0108] If desired, all batteries can be charged and connected to the electromagnet as shown in the lower part of FIG. When the electromagnet is not in use (e.g., between patients), MRI imaging is in progress. If not already done, the electromagnet may be kept warm.

[0109] One or more batteries are used to insulate the electromagnet from power supply fluctuations. However, the present disclosure further proposes utilizing fuel cells in a similar manner. As shown in FIG. 12, the system includes a fuel cell disposed between a power source and a resistive electromagnet; It may be configured to substantially filter out voltage fluctuations occurring on the power supply. .

[0110] One or more aspects or features of the subject matter described herein may include digital electronic circuits, integrated Circuits, specially designed application specific integrated circuits (ASICs), field programmable Gate Array (FPGA) computer hardware, firmware, software and and / or combinations thereof. Characterized by at least one programmable processor, whether purpose-specific or general-purpose. a programmable controller including at least one input device and at least one output device; One or more computer programs executable and / or interpretable by a microprocessor system. The programmable processor may include an implementation in a storage system. Receives data and instructions from the storage system and sends data and instructions to the storage system. Programmable or computing systems The system may include a client side and a server side. The client and the server communicate They are usually located remotely from each other and communicate via a communication network. The client-server relationship is achieved by two computers running the same client and server. This is caused by computer programs in a client-server relationship.

[0111] These computer programs are also known as programs, software, and software applications. Also called an application, component or code, It includes machine instructions for multiprocessors, high-level procedural languages, object-oriented programming languages, programming language, functional programming language, logic programming language and / or assembly language As used herein, a "machine-readable medium" (or The term "computer-readable medium" refers to any computer program product, apparatus, and and / or devices, such as magnetic disks, optical disks, memories and programmable These refer to PLDs, etc. that store machine instructions and / or data. to a programmable processor, and machine instructions as machine-readable signals. "Machine-readable signal" (or "computer-readable signal") includes a machine-readable medium that receives The term "programming language" refers to a language for providing machine instructions and / or data to a programmable processor. A machine-readable medium is a non-transitory, machine-readable medium. Such machine instructions may be stored in a non-transitory manner, e.g., in a non-transitory solid-state memory. stored in a manner similar to a memory or magnetic hard drive or any equivalent storage medium Alternatively or additionally, the machine-readable medium may include a The instructions may be temporarily stored, for example in a processor cache or in one or more physical processors. The data is stored in the same manner as other random access memories associated with the SACORE. It is acceptable to do so.

[0112] To achieve user interaction, one or more aspects of the subject matter described herein may be or feature is a display device, e.g., a cathode ray tube (CRT), which displays information to a user. ) or Liquid Crystal Display (LCD) or Light Emitting Diode (LED) monitor and user keyboards and pointing devices for inputting information to a computer, e.g. The present invention may be implemented in a computer with a mouse or trackball, etc. For example, a user may be given The feedback may be any form of sensor feedback, for example, visual feedback. Feedback from the user can be provided in the form of audio feedback or haptic feedback. The input may be in any form, including but not limited to acoustic input, voice input, or tactile input. Other possible input devices include, but are not limited to, a touch Touch screen or other touch-sensitive device, e.g. single point or Multi-point resistive or capacitive trackpad, sound Voice recognition hardware and software, optical scanners, optical pointers, digital imaging The present invention includes a capture device and corresponding interpretation software.

[0113] In the above description and claims, "at least one of" or "of" After an expression such as "one or more of," multiple elements or features may be listed with conjunctions. The term "and / or" also applies when more than one element or feature is listed. These expressions may be implicit or explicit in the context in which they are used. Unless expressly stated to the contrary, any listed element or feature may be used individually or in combination with any other element or feature. means any combination of any of the elements or features described with any of the remaining elements or features. For example, "at least one of A and B" is intended to mean a combination of A and B. "at least one of," "one or more of A and B," and "A and / or B" The expressions are intended to mean "A only," "B only," or "A and B," respectively. The same interpretation shall apply when three or more items are listed. For example, "A, "At least one of B and C," "one or more of A, B, and C," and "A , B and / or C" means "A only", "B only", "C only", means "A and B", "A and C", "B and C" or "A and B and C" It is intended that the term "based on" be used in the above description and claims. When used in the above example, the term "at least one of" is used to indicate that unrecited features or elements may also be considered. "based in part on" is intended to mean "based in part on

[0114] The subject matter described herein may be implemented as a system, apparatus, method, computer, or other device, depending on the desired configuration. The present invention may be embodied in a program and / or article as illustrated in the accompanying drawings. Any method or logic flow described herein may be implemented in a manner that is consistent with the principles of the present invention to achieve a desired result. The above description does not necessarily require the particular order or sequential order shown. The described embodiments are not intended to represent all embodiments consistent with the subject matter described herein. Instead, here are some examples that correspond to various aspects of the subject matter being discussed: Although some modifications have been described in detail above, modifications or additions may be made in other respects. In particular, further features and / or methods may be provided in addition to those described herein. The above-described embodiments may include various combinations of the disclosed features. combinations and subcombinations and / or combinations of the further features set forth above. Further, the advantages of the present invention may be related to the above-described combinations and subcombinations. However, claims are made to processes and structures that achieve any or all of these advantages. It is not intended to limit the applicability of the paragraph.

[0115] In addition, the section titles are provided to clarify the invention as it relates to the claims based on this disclosure. Further, the description of the technology described in the "Background Art" is not intended to limit or characterize the present invention. ", and should not be construed as an admission that such art is prior art to the invention(s) in this disclosure. The "Summary of the Invention" statement shall also be construed as characterizing the invention as set forth in the claims. Moreover, when referring to this disclosure generally or to the term "invention," The use of the singular "a," "the," or "the" implies a limitation on the scope of the claims set forth below. It is not intended that multiple claims be made in accordance with the limitations of multiple claims based on this disclosure. These claims may therefore be interpreted as describing multiple inventions and their defines multiple equivalents of these.

Claims

1. 1. A magnetic resonance imaging (MRI) system comprising: a resistive electromagnet for whole-body MRI, the resistive electromagnet having a magnetic field strength of at least 0.05 Tesla and including a conductor for generating a main magnetic field of the resistive electromagnet; a power supply for supplying power to the normal conducting electromagnet, the power supply having a current fluctuation between 1 part in 10,000 and 1 part in 1,000 at a frequency of 180 Hz or more; A system comprising:

2. The system of claim 1 , wherein the resistive electromagnet is a solenoidal electromagnet having no gap.

3. 2. The system of claim 1, which does not include a current filter separate from the filtering function provided by the resistive electromagnet itself.

4. The system of claim 1 , further comprising a current filter comprising an inductor having an inductance of less than 2 mH, separate from the filtering function provided by the resistive electromagnet itself.

5. The system of claim 1 , wherein the power supply is a single channel power supply.

6. 6. The system of claim 5, configured to compensate for low frequency current drift or low frequency voltage drift by modifying the main magnetic field strength.

7. The system of claim 1 , wherein the power supply does not have active current control.

8. The system of claim 1 further comprising a filter for controlling voltage fluctuations.

9. The system of claim 8 , wherein the filter for controlling voltage fluctuations is an LC filter.

10. The system of claim 1 , further comprising a battery, the resistive electromagnet being connected to the battery, and the system being configured such that the battery is charged by the power source.

11. 2. The system of claim 1, further comprising a plurality of batteries, the system being configured such that while the resistive electromagnet is connected to one of the plurality of batteries, another of the plurality of batteries can be charged by the power source.

12. 2. The system of claim 1, further comprising at least three batteries, the system being configured such that a second battery is charged while the resistive electromagnet is connected to a first battery, and the system is further configured such that a connection of the resistive electromagnet is switched to a third battery that is not being charged upon switching the connection.

13. The system of claim 1 , further comprising a fuel cell, the system being configured such that the fuel cell is disposed between the power source and the resistive electromagnet.

14. The system of claim 1 , wherein the resistive electromagnet is solenoidal, has a gap, and includes a ferromagnetic material disposed within an envelope of the resistive electromagnet.

15. The system of claim 14 , wherein the conductor is directly cooled.

16. The system of claim 14 , wherein the conductor is copper.

17. 17. The system of claim 16, wherein the resistive electromagnet has a magnetic field strength of at least 0.12 Tesla and a power source of less than 30 kW.

18. 17. The system of claim 16, wherein the resistive electromagnet has a magnetic field strength of at least 0.2 Tesla and a power source of less than 100 kW.

19. 17. The system of claim 16, wherein the resistive electromagnet has a magnetic field strength of at least 0.3 Tesla and a power source of less than 210 kW.

20. The system of claim 14 , wherein the conductor is aluminum.

21. 21. The system of claim 20, wherein the resistive electromagnet has a magnetic field strength of at least 0.12 Tesla and a power source of less than 45 kW.

22. 21. The system of claim 20, wherein the resistive electromagnet has a magnetic field strength of at least 0.2 Tesla and a power source of less than 155 kW.

23. 21. The system of claim 20, wherein the resistive electromagnet has a magnetic field strength of at least 0.3 Tesla and a power source of less than 335 kW.

24. The system of claim 14 , wherein the conductor is indirectly cooled.

25. 25. The system of claim 24, further comprising a serpentine coolant channel adjacent at least one of the conductors to provide the indirect cooling.

26. 26. The system of claim 25, wherein the serpentine coolant channel includes an inlet and an outlet located at a patient end or a service end of the MRI system.

27. 25. The system of claim 24, wherein the conductor is copper.

28. 28. The system of claim 27, wherein the resistive electromagnet has a magnetic field strength of at least 0.12 Tesla and a power source of less than 35 kW.

29. 28. The system of claim 27, wherein the resistive electromagnet has a magnetic field strength of at least 0.2 Tesla and a power source of less than 105 kW.

30. 28. The system of claim 27, wherein the resistive electromagnet has a magnetic field strength of at least 0.3 Tesla and a power source of less than 230 kW.

31. 25. The system of claim 24, wherein the conductor is aluminum.

32. 32. The system of claim 31, wherein the resistive electromagnet has a magnetic field strength of at least 0.12 Tesla and a power source of less than 50 kW.

33. 32. The system of claim 31, wherein the resistive electromagnet has a magnetic field strength of at least 0.2 Tesla and a power source of less than 170 kW.

34. 32. The system of claim 31, wherein the resistive electromagnet has a magnetic field strength of at least 0.3 Tesla and a power source of less than 365 kW.

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