Magnetic resonance imaging machine having low power demand

Abstract

The invention relates to a magnetic resonance imaging machine (1), in particular a magnetic resonance tomography machine (2), comprising a main magnet (3) and a cold head (4) cooling the main magnet (3), wherein the cold head (4) can be operated by means of a single-phase power connection (5) delivering a voltage of 240 V or less, and / or can be operated without water cooling, in particular by means of air cooling, and wherein the main magnet (3) is made of a high-temperature superconductor. The invention also relates to a magnetic resonance imaging machine (1), in particular a magnetic resonance tomography machine (2), comprising a gradient system (6) and an accumulator (7), wherein the accumulator (7) is connected via a power cable (8) to the gradient system (6) for supplying power thereto, and wherein the accumulator (7) has a connection (9) via which the accumulator (7) can be charged by means of a single-phase power source (10) delivering a voltage of 240 V or less, in particular a photovoltaic installation. The invention also relates to corresponding methods for operating a magnetic resonance imaging machine (1), in particular a magnetic resonance tomography machine (2).

Description

[0001] Low-power magnetic resonance imaging device

[0002] The invention relates to a magnetic resonance device, which can be designed in particular as a magnetic resonance tomography device, with a main magnet and a cold head cooling the main magnet.

[0003] The invention further relates to a magnetic resonance device, which can be designed in particular as a magnetic resonance tomography device, with a gradient system and an accumulator.

[0004] The invention further relates to a method for operating a magnetic resonance apparatus, in particular a magnetic resonance tomography apparatus, which has a main magnet and a cold head cooling the main magnet.

[0005] The invention further relates to a method for operating a magnetic resonance apparatus, in particular a magnetic resonance tomography apparatus, which has a gradient system and an accumulator.

[0006] Such magnetic resonance devices are used, for example, in medicine and chemistry, as well as in engineering and geosciences. These include devices for magnetic resonance spectroscopy and nuclear magnetic resonance spectroscopy. These devices are particularly used in imaging when designed as magnetic resonance imaging devices, which generally require the presence of a gradient system.

[0007] Such devices have a main magnet, which typically generates a nearly constant main magnetic field within a measurement volume and is usually superconducting or made of a superconducting material. Since the main magnet only enters its superconducting state below a certain transition temperature, usually only a few degrees Kelvin, it requires complex cooling. Liquid helium is typically used for this purpose, which is cooled by a cold head, consuming a high amount of electricity.

[0008] If such devices are designed as tomographs, a gradient system is usually required, which has several coils that generate a variable magnetic field. Switching these coils of the gradient system also involves high electrical energy consumption.

[0009] The object of the invention is to reduce the energy consumption of magnetic resonance devices and magnetic resonance tomography devices.

[0010] To achieve the stated object, the features of claim 1 are provided according to the invention. In particular, to achieve the stated object, in magnetic resonance devices, in particular in magnetic resonance tomography devices, of the type described above, it is proposed according to the invention that the cold head can be operated by means of a single-phase power connection delivering a voltage of 240 V or less and / or without water cooling, in particular air-cooled, and that the main magnet is made of a high-temperature superconductor.

[0011] The main magnet can, for example, provide a magnetic flux density between 0.1 T and 7 T, preferably between 0.3 T and 4 T, particularly preferably 0.5 T.

[0012] The high-temperature superconductor (HTS) can, for example, be a first-generation HTS superconductor. Such a superconductor can be characterized by the superconducting nature of a filament of bismuth-strontium-calcium-copper oxide (also referred to as "BiSCCO") enclosed in a matrix. Furthermore, the high-temperature superconductor can also be a second-generation HTS, for example. Such a superconductor can be characterized by the fact that a superconducting layer consisting of at least one rare earth element is applied to a suitable carrier material.

[0013] High-temperature superconductors are characterized by their transition temperature of at least 30 Kelvin up to 250 Kelvin. For example, superconductors with transition temperatures above 77 Kelvin and / or above 195 Kelvin can be selected, allowing dry conductive cooling, liquid nitrogen, or dry ice to be used for cooling. The use of liquid helium is thus unnecessary.

[0014] The use of a high-temperature superconductor thus reduces the cooling effort and opens up the possibility of using cold heads which have a lower energy consumption.

[0015] In this way, it is possible to operate the respective cold head using a single-phase power supply delivering a voltage of 240 V or less. Alternatively or additionally, water cooling is dispensable; air cooling of the cold head may be sufficient for its operation. The cooling of the main magnet by the cold head can be achieved indirectly, for example, by means of a coolant, in particular one of the aforementioned coolants.

[0016] In an advantageous embodiment, it can be provided that the main magnet comprises annular double disks, each double disk comprising two disks wound from a high-temperature superconductor. An insulating disk is arranged between the disks of a double disk. The insulating disk can, for example, have a core made of copper. The main magnet can be conductively cooled via the insulating disk. This can be done, for example, by cooling the insulating disk with the cold head described above. For this purpose, the cold head can be connected to the insulating disk via an electrical conductor, in particular via stranded wires, which can, for example, be made of copper.

[0017] Copper can be particularly well suited as a material for the core and / or for the stranded wire due to its high thermal conductivity at low temperatures, for example at temperatures below 60 Kelvin.

[0018] In addition, the insulating pane can have an electrically insulating layer on its sides facing the panes. Thus, the insulating pane can be both thermally conductive and electrically insulating.

[0019] The double discs are connected to each other via connecting parts. The connecting parts can, for example, be attached to an outer contour of the double discs. This makes it possible to assemble the main magnet from a large number of double discs, particularly in an axial direction, and to vary the length of the main magnet.

[0020] Preferably, the discs have different inner and / or outer radii. This allows for greater design flexibility with regard to the geometry of the main magnet and can improve the homogeneity of the magnetic field to be generated.

[0021] In a further advantageous embodiment, the main magnet can be uncast. Uncast here means that the area in which the main magnet is arranged—for example, in the form of windings of a high-temperature superconductor—is not cast with a plastic, such as an epoxy resin. This allows the windings to be removed without damage if necessary. This can facilitate maintenance and also enable reuse and / or recycling of the high-temperature superconductor.

[0022] In a further advantageous embodiment, the main magnet may have windings that are wound with a mechanical preload. The windings may be the discs and / or double discs described above.

[0023] The presence of a mechanical prestress in the windings can be particularly advantageous if the main magnet is not encapsulated. This can result in the windings of the main magnet being moved radially outwards due to the resulting Lorentz forces. This increases the radius of the windings, which can lead to inhomogeneities in the magnetic field. In addition, the larger radius leads to tensile forces along the windings, which can cause the windings to break. This danger exists particularly at high magnetic flux densities, for example in the range of 14 Tesla. These effects can be counteracted by winding the windings with a mechanical prestress.

[0024] In a further advantageous embodiment, it can be provided that an external closure is arranged on the outside around the windings of the main magnet, which closure prevents any outward displacement of the windings. In this way, the magnetic field can be kept stable. The closure preferably comprises at least one overwinding. Particularly preferably, the overwinding has a tear strength which exceeds a tear strength of the windings of the main magnet. This overwinding can prevent the radius of the windings from increasing, as described above, because the overwinding can mechanically support the windings of the main magnet. In addition, tearing of the windings of the main magnet can also be prevented in this way.

[0025] In a further advantageous embodiment, a lubricating grease can be introduced into a region in which the windings are arranged. Preferably, the lubricating grease is fluid at a processing temperature and solid at an operating temperature of the main magnet.

[0026] The processing temperature can be a temperature that is present, for example, during maintenance and / or installation and / or repair work. The fluidity of the grease allows it to be easily applied to the area. Furthermore, the windings of the main magnet can be removed from the main magnet if necessary. This promotes potential reuse and / or recycling of the high-temperature superconductor.

[0027] At the main magnet's operating temperature, the lubricating grease, which is now in a solid state, can mechanically support the main magnet's windings. This can also prevent an increase in the winding radius and / or breakage of the windings.

[0028] In a further advantageous embodiment, the main magnet can be electrically supplied via a stabilized power supply. This ensures that a constant voltage is always applied to the main magnet, so that the generated magnetic field can be kept stable.

[0029] Alternatively or additionally, to achieve the stated object, the features of the independent claim 2 directed to a magnetic resonance device, in particular a magnetic resonance tomography device, having a gradient system and a rechargeable battery are provided according to the invention. In particular, to achieve the stated object, in magnetic resonance devices, in particular magnetic resonance tomography devices, of the type described at the outset, it is proposed according to the invention that the rechargeable battery is connected via a power cable to the gradient system for supplying power to the latter, and that the rechargeable battery has a connection via which the rechargeable battery can be charged by means of a single-phase power source, in particular a photovoltaic system, supplying a voltage of 240 V or less.

[0030] The power supply of the gradient system is intended in particular for switching gradients. When switching the gradient system, high currents are required within a short period of time. In order to make this available to the gradient system, a complex power supply, for example with three-phase alternating current, was previously necessary. According to the invention, this is replaced by an accumulator which can store the required amount of electrical energy, but can itself be charged using a single-phase power source delivering a voltage of 240 V or less. This reduces the effort required to produce an adequate power supply, thus also enabling the use of a photovoltaic system as a power source. In an advantageous embodiment, it can be provided that the start-up process of the magnetic resonance imaging device takes more than one hour.The duration is preferably between four and eight hours. For example, the duration is six hours. This can counteract the occurrence of so-called "screening currents" – eddy currents in the superconducting structure of the main magnet that can prevent the main magnet from starting up. This can improve the stability of the magnetic field.

[0031] Alternatively or additionally, to achieve the stated object, the features of the independent claim 3 directed to a method for operating a magnetic resonance apparatus, in particular a magnetic resonance tomography apparatus, which has a main magnet and a cold head cooling the main magnet are provided according to the invention. In particular, to achieve the stated object, a method of the type described at the outset is proposed according to the invention in that the cold head is operated by means of a single-phase power connection supplying a voltage of 240 V or less and / or is water-cooled, in particular air-cooled, and in that a magnet made of a high-temperature superconductor is used as the main magnet.

[0032] Thus, the previously explained advantages of magnetic resonance devices or magnetic resonance tomography devices according to the invention, which have a main magnet and a cold head cooling the main magnet, can be used in methods of the type described above.

[0033] Alternatively or additionally, to solve the above-mentioned

[0034] According to the invention, the features of the independent claim 4, which is directed to a method for operating a magnetic resonance apparatus, in particular a magnetic resonance tomography apparatus, which has a gradient system and a rechargeable battery, are provided for this purpose. In particular, to achieve the stated object, the method of the type described at the outset is proposed according to the invention in that the rechargeable battery is connected to the gradient system via a power cable to supply power to the system, and in that the rechargeable battery has a connection via which the rechargeable battery is charged by means of a single-phase power source, in particular a photovoltaic system, which supplies a voltage of 240 V or less.

[0035] Thus, the previously explained advantages of magnetic resonance devices or magnetic resonance tomography devices according to the invention, which have a gradient system and an accumulator, can be used in methods of the type described above.

[0036] The devices and methods according to the invention enable the design of devices with low power consumption, whereby connection to a photovoltaic system may be sufficient for their operation. For example, the devices and methods according to the invention can draw the required electrical energy exclusively from single-phase power sources delivering a voltage of 240 V or less.

[0037] The device does not have to be a fixed installation device, but can also be a portable device.

[0038] To enable portable use, for example, in areas with little infrastructure, a water reservoir, such as a water tank, can be additionally designed to provide cooling water for the gradient system, for example. This increases the portability of the respective device.

[0039] The invention will now be described in more detail using an exemplary embodiment, but is not limited to the exemplary embodiment. Further exemplary embodiments result from combining the features of one or more claims with one another and / or with one or more features of the exemplary embodiment.

[0040] It shows :

[0041] Fig. 1 is a simplified representation of a magnetic resonance apparatus according to the invention,

[0042] Fig. 2 shows a longitudinal section of a main magnet according to the invention.

[0043] The magnetic resonance device 1 shown in Figure 1 is designed as a magnetic resonance imaging device 2 and has at least one main magnet 3 and a cold head 4 that cools the main magnet 3. The cold head 4 can be operated via a single-phase power supply 5 delivering a voltage of 240 V or less and is water-cooled, namely air-cooled. The cold head 4 has a compressor 11 and pressure lines 12. The main magnet 3 is made of a high-temperature superconductor.

[0044] The magnetic resonance scanner 1 further comprises a gradient system 6 and a rechargeable battery 7, wherein the rechargeable battery 7 is connected to the gradient system 6 via a power cable 8 to supply power to the system. The rechargeable battery 7 has a connection 9 via which the rechargeable battery 7 can be charged using a single-phase power source 10 supplying a voltage of 240 V or less. In an embodiment not shown, the power source 10 can be a photovoltaic system.

[0045] Furthermore, the main magnet 3 is supplied with electrical energy via a further power source 18. For this purpose, a stabilized power supply 17 is provided, which ensures a constant output voltage. The magnetic field generated by the main magnet 3 is thus particularly stable. The magnetic resonance device 1 or magnetic resonance tomography device 2 shown can be used to carry out the inventive methods for operating a magnetic resonance device 1 and a magnetic resonance tomography device 2. The cold head 4 is operated by means of the single-phase power connection 5, which supplies a voltage of 240 V or less, and is water-cooled, namely air-cooled. Furthermore, a magnet made of a high-temperature superconductor is used as the main magnet 3.

[0046] In the method according to the invention, it is also possible for the accumulator 7 to be charged via the connection 9 using the single-phase power source 10 delivering a voltage of 240 V or less. Within the scope of this method according to the invention, the power source 10 can also be a photovoltaic system in an embodiment not shown.

[0047] The device may also have a radio frequency system, a computing system and / or antenna system not shown in detail.

[0048] Furthermore, the start-up process for the magnetic resonance imaging device 1 is planned to last six hours. This counteracts the occurrence of eddy currents.

[0049] Figure 2 shows a section of a longitudinal section of the main magnet 3. The windings 13 of the main magnet are designed to be substantially rotationally symmetrical about an axis of symmetry 26.

[0050] Three double disks 20 are visible. Each of these double disks 20 consists of two disks 21, 21'. The disks 21, 21' represent a winding 13 of a high-temperature superconductor.

[0051] The windings 13 are wound with a mechanical pretension. This makes the windings 13 particularly stable, especially against the Lorentz forces that occur during operation of the main magnet 3.

[0052] An insulating disk 23 is arranged between each of the disks 21, 21' of a double disk 20. This is made of a copper core coated with an electrical insulating layer and serves to cool the main magnet 3.

[0053] In the illustrated embodiment, the disks 21, 21' of each double disk 20 have the same inner radius 24. This simplifies the manufacture of the double disks 20: The respective disks 21, 21' can be wound in one and the same shape, which has a specific radius, during manufacture.

[0054] The three double discs 20 have different inner radii 24. This allows the shape of the main magnet 3 to be flexibly adjusted to provide the most homogeneous magnetic field possible.

[0055] On the inside, the double discs 20 can be wound on a carrier not shown.

[0056] It can also be seen that the outer radii 25 of the disks 21, 21' are of different sizes. Adjacent disks 21, 21', which do not belong to the same double disk 20, have the same outer radius 25 in the exemplary embodiment described here. This is advantageous because in this way the double disks can be easily connected to one another via connecting parts 22. The connecting parts 22 rest on the outer circumference of the disks 21, 21'.

[0057] The windings 13 are mechanically supported on the outer circumference by a closure 19. The closure 19 is designed here as overwindings 14 adjacent to the windings 13. The overwindings 14 have a higher tensile strength than the windings 13.

[0058] The area 16 in which the windings 13 are arranged is uncast and filled with a lubricating grease 15. At the operating temperature of the main magnet 3, the lubricating grease 15 is in a solid state, so that—like the closure 19—it mechanically supports the windings 13. At a processing temperature—which occurs, for example, during assembly or a maintenance procedure—the lubricating grease 15 is liquid. This allows it to be easily applied to the area 16.

[0059] A magnetic resonance device 1, in particular a magnetic resonance tomography device 2, is thus proposed, having a main magnet 3 and a cold head 4 cooling the main magnet 3, wherein the cold head 4 can be operated by means of a single-phase power connection 5 delivering a voltage of 240 V or less and / or without water cooling, in particular air-cooled, and wherein the main magnet 3 is made of a high-temperature superconductor. Furthermore, a magnetic resonance device 1, in particular a magnetic resonance tomography device 2, with a gradient system 6 and a rechargeable battery 7 is proposed, wherein the rechargeable battery 7 is connected to the gradient system 6 via a power cable 8 to supply power to the system, and wherein the rechargeable battery 7 has a connection 9 via which the rechargeable battery 7 can be charged by means of a single-phase power source 10, in particular a photovoltaic system, which supplies a voltage of 240 V or less.Furthermore, corresponding methods for operating a magnetic resonance device 1, in particular a magnetic resonance tomography device 2, are proposed, cf. Fig. 1.

[0060] List of reference symbols Magnetic resonance device Magnetic resonance imaging device Main magnet Cold head Power connection Gradient system Accumulator Power cable Power source connection Compressor Pressure line Winding (of 3) Overwinding Grease area (of 13) Stabilized power supply Additional power source Closure Double disc Disc Connecting part I Insulating disc Inner radius (of 21) Outer radius (of 21) Symmetry axis (of 3)

Claims

Claims 1. Magnetic resonance device (1), in particular a magnetic resonance tomography device (2), with a main magnet (3) and a cold head (4) cooling the main magnet (3), wherein the cold head (4) can be operated by means of a single-phase power connection (5) delivering a voltage of 240 V or less and / or without water cooling, in particular air-cooled, and wherein the main magnet (3) is made of a high-temperature superconductor.

2. Magnetic resonance apparatus (1) according to the preceding claim, characterized in that the main magnet (3) comprises annular double disks (20), each double disk (20) comprising two disks (21, 21') wound from a high-temperature superconductor, an insulating disk (23) being arranged between the disks (21, 21') of a double disk (20), and the double disks (20) being connected to one another via connecting parts (22), in particular the disks (21, 21') having different inner radii (24) and / or outer radii (25).

3. Magnetic resonance apparatus (1) according to one of the preceding claims, characterized in that the main magnet (3) is uncast.

4. Magnetic resonance apparatus (1) according to one of the preceding claims, characterized in that the main magnet (3) windings (13) which are wound with a mechanical pre-tension.

5. Magnetic resonance apparatus (1) according to one of the preceding claims, characterized in that on the outside An external closure (19) is arranged between the windings (13) of the main magnet (3), which closure prevents the windings (13) from being displaced outwards, in particular wherein the closure (19) comprises at least one overwinding (14) which preferably has a tear strength which exceeds a tear strength of the windings (13) of the main magnet (3).

6. Magnetic resonance apparatus (1) according to one of the preceding claims, characterized in that in a region (16) in which the windings (13) are arranged, a lubricating grease (15) is introduced, in particular wherein the lubricating grease (15) is flowable at a processing temperature and is solid at an operating temperature of the main magnet (3).

7. Magnetic resonance apparatus (1) according to one of the preceding claims, characterized in that the main magnet (3) can be electrically supplied via a stabilized power supply (17).

8. Magnetic resonance device (1), in particular a magnetic resonance tomography device (2), with a gradient system (6) and an accumulator (7), wherein the accumulator (7) is connected via a power cable (8) to the gradient system (6) for its power supply and wherein the accumulator (7) has a connection (9) via which the accumulator (7) can be charged by means of a single-phase power source (10) supplying a voltage of 240 V or less, in particular a photovoltaic system.

9. Method for operating a magnetic resonance device (1), in particular a magnetic resonance tomography device (2), which has a main magnet (3) and a Main magnet (3) cooling cold head (4), wherein the cold head (4) is operated by means of a single-phase power connection (5) delivering a voltage of 240 V or less and / or without water cooling, in particular air-cooled, and wherein a magnet made of a high-temperature superconductor is used as the main magnet (3).

10. Method according to the preceding claim, characterized in that a time duration of a start-up process of the magnetic resonance device (1) is more than one hour, preferably between four and eight hours, for example a time duration of six hours.

11. Method for operating a magnetic resonance device (1), in particular a magnetic resonance tomography device (2), which has a gradient system (6) and an accumulator (7), wherein the accumulator (7) is connected via a power cable (8) to the gradient system (6) for its power supply and wherein the accumulator (7) has a connection (9) via which the accumulator (7) is charged by means of a single-phase power source (10) supplying a voltage of 240 V or less, in particular a photovoltaic system.

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