DE102021109910A1 - Valve arrangement for magnetic resonance tomography systems and magnetic resonance tomography system - Google Patents

Abstract

The invention relates to a quench tube (50) for a magnetic resonance tomography system (40), the quench tube (50) comprising a valve arrangement (1) for shutting off the quench tube (50). The invention also includes a magnetic resonance tomography system (40) with a quench tube (50).

Description

The invention relates to a valve arrangement for a magnetic resonance tomography system and a magnetic resonance tomography system with a valve arrangement.

Magnetic resonance tomography is an imaging method that is used primarily in medical diagnostics to display the structure and function of tissues and organs in the body. With magnetic resonance tomography, cross-sectional images of the human (or animal) body can be generated, which allow an assessment of the organs and many pathological organ changes. Physically, it is based on the principles of nuclear magnetic resonance, in particular field gradient nuclear magnetic resonance. This is based on very strong static magnetic fields and alternating magnetic fields in the radio frequency range, with which certain atomic nuclei, usually the hydrogen nuclei/protons, are resonantly excited in the body, which induces an electrical signal in a receiver circuit. The stationary magnetic fields and the alternating magnetic fields are generated in a magnetic resonance tomography system, referred to below as an MRT system. Electromagnets with coils made of so-called superconductors, i.e. materials that have almost no electrical resistance at very low temperatures, are used to generate the static magnetic field. The necessary temperature control of the superconductors to a temperature of just a few Kelvin, usually around 4 K, is achieved using liquid helium. In the event that the liquid or gaseous helium has to be drained, for example for maintenance of the electromagnetic coils, so-called quench tubes are connected to the area of the MRT system that is filled with liquid helium. The quench tubes ensure that when the liquid helium is released, there is no danger to persons or other parts of the MRI system or the buildings from the liquid helium. Particularly in the event of an emergency shutdown, the strong magnetic field is reduced by rapidly releasing the helium, a process known as quenching. Due to the increasing resistance in the superconductor associated with the heating of the superconductor, the strength of the generated magnetic field is quickly reduced.

In addition, the helium must also be able to be released safely for maintenance or repair work on the electromagnetic coils or other parts of the MRI system. In the prior art, if there are two or more MRT systems in a building, such as in large hospitals or in training centers at manufacturers of MRT systems, either a separate quench tube is routed outside for each MRT system or it are connected via T-pieces to the quench pipes of several MRI systems to a common discharge to the outside.

However, the latter solution has the disadvantage that in the event of maintenance or repairs, all connected MRI systems must be shut down for safety reasons in order to prevent helium from escaping from the quench tube of the MRI, which is open in this case, in the event of a quench in one of the connected systems system to be serviced. In addition to significant additional costs for refilling all MRI systems with helium, this also leads to reduced availability of the MRI systems, which in turn can lead to downtime costs.

The object of the present invention is to provide a valve arrangement and an MRT system which eliminate the disadvantages of the prior art described above.

This object is achieved by a valve arrangement having the features of independent claim 1 and an MRT system having the features of claim 12. The dependent claims relate to advantageous developments and variants of the invention.

A quench tube according to the invention for a magnetic resonance tomography system, referred to below as an MRT system, comprises a valve arrangement for shutting off the quench tube according to the invention. The quench tube can advantageously be closed within the MRT system by the valve arrangement according to the invention. As a result, in particular in cases where several MRI systems are connected via quench tubes to an outlet, which means the part of the quench tube that leads outside the MRI system through a building to the outside, during maintenance of one of the MRI backflow of helium into the serviced MRI system.

The valve arrangement can include a valve for shutting off the quench tube. In this case, the valve can be arranged in a housing of the valve arrangement which, for example, comprises a pipe section which comprises the valve and/or a screw drive for moving the valve. The pipe section, which is part of the valve arrangement and thus also part of the quench pipe, usually has the same diameter as the quench pipe and can be connected to the quench pipe via two flanges arranged on both sides of the pipe section.

Furthermore, the valve can be made in one piece or in two pieces, with the number of parts referring to a slide comprised by the valve. In the case of a one-piece valve, the slide can enter a groove formed in a pipe section of the valve arrangement from above, from below or from the side and thereby close the quench pipe. The groove for inserting the slide into the pipe section of the valve arrangement is formed circumferentially, so that the pipe section is divided into two sub-sections within the valve arrangement. A first area of the slide comprises a closed surface, so that the pipe section is closed by the slide in a first closed position. In a second open position, the slide can be moved in such a way that an opening arranged in a second area of the slide, which corresponds to the inner diameter of the pipe section, is positioned in such a way that a continuous inner surface of the pipe section is ensured, i.e. no edges or shoulders are present are. The helium can flow unhindered into the quench tube.

In the case of a two-part valve, a first part of the valve can be designed as a slide for closing the quench tube. The slide can only be pushed in from one direction, for example from one side, which means that the groove in the quench pipe advantageously only runs over 180°, so the pipe section of the valve arrangement is not completely separated, which means that there is a lower leakage rate through the gap between the slide and the Groove resulting gap can be achieved. At least in some areas, the slide has a radius that is adapted to the inner radius of the pipe section, this area being in contact with the inner surface of the pipe in a closed position. This prevents helium from flowing unhindered from another MRI system into the MRI system to be serviced. Due to the helium flowing at only a very low pressure, the sealing effect of the slide on the inside of the pipe section, ie metal on metal, is sufficient. To improve the tightness, the adapted area of the slide can also include a sealing lip, which seals the gap between the slide and the inner surface of the pipe section, as a result of which a helium-tight seal can also be achieved. This is expediently designed to be temperature-resistant to the temperatures generated by the helium.

In the open position, the slide can be pulled completely out of the pipe section. The now open groove can be sealed by a second part of the valve designed as a sealing clip, which includes a spring corresponding to the groove. The spring can be designed with the same height as the wall thickness of the pipe section, so that no edges or shoulders are formed on the inner surface of the pipe section, as is the case with the one-piece slide. Two surfaces adjoining both sides of the root of the tongue can additionally seal the gaps occurring between the tongue and the groove. A seal can also be arranged between these lateral surfaces and the outer surface of the tube, which are expediently designed to be temperature-resistant with respect to the temperatures of the helium. A paper seal is particularly suitable here, for example using the material available on the market under the Unitec 300 brand.

In particular, the seal of the quench tube can be designed to be helium-tight.

Furthermore, the first part can be connected at least temporarily to the second part of the slide via a driver. The driver can be designed as a recess in the first part, into which a projection, designed as a screw head, of the second part dips during a movement perpendicular to the first part. As a result, the second part is carried along with the movement of the first part.

In particular, the two parts connected via the driver can be moved by a first drive. This has the advantage that the sealing clip can be driven in at least one direction of movement with the drive of the slide, which is designed as a screw drive.

Furthermore, the second part can be moved by a second drive perpendicular to the movement of the first drive relative to the first part. In the event that the slider is to be pushed into the groove, the sealing clip can be moved perpendicularly to the direction of movement of the slider with the second drive designed as a screw drive in order to avoid a collision. Alternatively, this movement can also be realized by suitable kinematics. The two screw drives can be driven either manually or electrically. Since the valve is only rarely adjusted, the electric drive can also be designed in the form of a cordless screwdriver, which can be connected to the threaded drives via a suitable interface.

In addition, the valve arrangement can be designed to be helium-tight. This has the advantage that helium which escapes through a leak in the sealing fork remains in the valve arrangement and cannot get into the environment. The helium is not under pressure during quenching and will always take the path of least resistance, i.e. flow in the direction of an outlet and not through a possible gap in the sealing clip.

In a further embodiment of the invention, the valve arrangement can include sensors for detecting at least a first and a second position of the valve. The positions can already be specified by stops, so that the sensors represent an additional safeguard. In addition, the signals detected by the sensors can be forwarded to a controller of the MRT system. Based on these signals, the controller can enable (open position) or prevent (closed position) operation of the MRI system. If there are several machines, the signals can also be transmitted to other MRI systems, so that the other systems can only be operated if, for example, the valve of the machine to be serviced is closed.

Furthermore, the invention includes an MRI system with a quench tube according to one of the embodiments described above.

In particular, the quench tube may have been retrofitted into an existing MRI system. The quench tube according to the invention can be easily integrated into existing systems by means of flanges, which can be designed, for example, according to the DIN standard or any other standard. The valve arrangement is adaptable for different sizes of DN pipes, such as DN 100, DN 150 or DN 300.

• 1 eine schematische Darstellung eines Magnetresonanztomographie-Systems,
• 2a,b eine erfindungsgemäße Ventilanordnung für ein Magnetresonanztomographie-System in einer offenen und einer geschlossenen Stellung,
• 3 eine Detailansicht der Ventilanordnung, und
• 4a,b eine weitere Ausführungsform einer Ventilanordnung.

Exemplary embodiments and variants of the invention are explained in more detail below with reference to the drawing. Show it

• 1 a schematic representation of a magnetic resonance imaging system,
• 2a,b a valve arrangement according to the invention for a magnetic resonance imaging system in an open and a closed position,
• 3 a detailed view of the valve assembly, and
• 4a,b another embodiment of a valve assembly.

1 shows a schematic representation of a magnetic resonance tomography system 40, which is divided into an examination area 41 and a technical area 47. The examination area 41 is the area in which a patient is positioned for examination and includes an electromagnetic coil 42 which is arranged in an enclosure 43 . The encapsulation 43 is filled with liquid helium 54 to cool the electromagnetic coil 42 . This can be drained into a quench tube 50 via a drain valve 45 arranged on a socket 44 of the encapsulation 43 for maintenance purposes or in an emergency to quickly reduce the magnetic field generated by the electromagnetic coil 42 . The first partial area 55 of the quench tube 50 is guided through a passage 46 into the technical area 47 and has a flange 48 at its end. A valve arrangement 1 according to the invention with a corresponding flange 6 is connected to this flange 48, thereby forming a first interface 49. The flange 6 is connected to a pipe section 4, which is guided through a housing 2 of the valve arrangement 1 and at its other end another Flange 9 includes. This is connected via a corresponding flange 52 of a second portion 56 of the quench tube 50 and thereby forms a second interface 51. The second portion 56 of the quench tube 50 is usually routed via a third part of the quench tube 50 designed as an outlet 53 from the MRT system 40 through the buildings surrounding the MRT system to the outside. The quench tube 50 thereby ensures that the very cold helium 54 is discharged to the outside without endangering people or objects. Several MRI systems 40 can also be connected to the outlet 53 of the quench tube 50, for example by means of T-pieces, which has the advantage that only one outlet 53 has to be routed to the outside. If several MRI systems 40 are connected to an outlet 53, it must be ensured during maintenance of one of the MRI systems 40 that no helium 54 originating from another system enters the MRI system to be maintained via the quench tube 50 40 can flow back. The valve arrangement 1 is therefore set up to close the quench tube 50 . In a further embodiment, the valve arrangement 1 can also be retrofitted to existing MRI systems 40, in which case the flanges 6, 9, 48, 52 of the interfaces 49, 51 can be designed as DIN flanges. The valve arrangement 1 and its components expediently comprise materials that are resistant to the low temperatures of helium, such as stainless steel or aluminum. In principle, all temperature-resistant materials can be used. Due to the extremely low temperatures of up to 4 Kelvin in the case of helium quenching and the associated strong temperature differences to which the valve arrangement 1 is exposed, the use of only one material such as stainless steel, for example 1.431 A2, 1.4301, 1.4304 or 1.4305 is preferred. When designing, especially when using different materials, care should be taken to ensure that the connections between The parts are designed in such a way that they work at room temperature and at 4 degrees Kelvin. Therefore, where possible and sensible, screw connections are preferable to material connections, such as welding. This has the advantage that after quenching, the valve assembly can be serviced and parts possibly damaged by the temperature fluctuations can be easily replaced.

2a shows a valve arrangement 1 according to the invention for a magnetic resonance tomography system, the valve arrangement 1 being shown with a two-part valve 36 in an open position. The valve assembly 1 includes a housing 2, which in the 2a and is shown transparently in all the following figures for reasons of clarity. The housing 2 comprises recesses 8 in two opposite side walls, through which a pipe section 4 passes. The recesses 8 are formed in such a way that the outer casing of the pipe section 4 bears against them, with the contact line being sealed off by weld seams 7 so as to be helium-tight. On both sides of the pipe section 4 there is a flange 6, 9 for connection to the first 55 and the second partial area 56 of the quench pipe 50, as already shown in FIG 1 explained, arranged.

The pipe section 4 has in the area which is within the housing 2, a groove 5 which in the 2a is represented by a break from the inside of the pipe section 4 forth. The groove 5 runs from the highest point of the pipe section 4 in both directions in each case 90° along the radius, ie over an angle of 180°. In the in the 2a In the open position of the two-part valve 36 shown, a first part of the valve 36 designed as a slide 10 is in a parking position, as a result of which the liquid helium can flow through the valve 36 unhindered and can be discharged via the quench tube 50 .

In this open position of the valve 36 , the groove 5 is closed by a second part of the valve 36 designed as a sealing clip 18 . The sealing clasp 18 includes a tongue 19 corresponding to the groove 5 , which is formed on an inner side of the sealing clasp 18 , which is designed in a semicircular manner and is directed towards the pipe section 4 . The height of the spring 19 corresponds to the wall thickness of the pipe section 4, so that a continuous inner surface of the pipe section 4, ie without a shoulder or an edge, is created. As a result, the outflowing helium is not swirled or partially slowed down and can flow off more easily, which advantageously counteracts possible icing of the pipe. The semicircular part of the sealing clasp 18 is wider than the spring 19 at the root of the spring 19 in the flow direction of the pipe section 4 , so that the sealing clasp 18 rests on both sides of the spring 19 on the outer surface of the pipe section 4 . The surfaces formed on both sides of the tongue 19 act as an additional seal, so that even helium, which flows through the gap between the tongue 19 and the groove 5, cannot get into the housing 2. Between the surfaces of the sealing clip 18 and the pipe section 4, additional sealing elements (not shown), such as a rubber seal, can optionally be arranged. The sealing element should expediently be designed to be temperature-resistant for the temperatures that may occur.

The sealing clasp 18 is in contact with the slide 10 in the illustrated position via a driver 32 which is formed in the part of the lever 35 of the sealing clasp 18 facing away from the pipe section 4 . As a result, the sealing clasp 18 is raised by the slide 10 when it is in the positive y-direction, which is defined by a Cartesian coordinate system in the 2a is defined, is proceeded. The screw drive 13 for moving the slide 10 is arranged in a cover 3 of the housing 2, which is screwed to the housing 2 and sealed with a suitable seal. This has the advantage that the slide 10 and the sealing fork 18 are easily accessible during maintenance. The screw drive 13 comprises a threaded rod 16 which runs in a bushing 15 which in turn is fixedly arranged in a bushing 14 in the cover 3 . The bushing 15 is welded in the bushing 14, with a helium-tight solution by means of a screw connection also being conceivable. The thread of the bushing 15 itself serves as a seal, which acts in the sense of a labyrinth seal. An interface 17 is formed on the end of the threaded rod 16 lying outside the cover 3 . Via this interface 17, the screw drive 13 can be driven manually or by an electric drive, such as a cordless screwdriver, but also via a controllable motor. The end of the threaded rod 16 lying in the housing 2 is firmly connected to the slide 10 . The slider 10 is guided by guides 11 during positioning. A guide 11 is arranged on the inner surfaces of the longitudinal sides of the housing 2 and a second guide 11 designed as a folded L-plate is connected to the slide 10 and guides the slide 10 in relation to the sealing clasp 18 .. The sealing clasp 18 is also by a Out guides 20, which comprise an F-shaped recess 21, in which in the in the 2a illustrated embodiment screw heads 22 are performed. As an alternative to the screw heads 22, pins or roller bearings can also be used. The guides 20 are each arranged in the region of the two arms of the sealing clip 18 and on the Housing 2 attached. After reaching an upper position, the sealing clasp 18 is moved in the x direction by a screw drive 24 so that the groove 5 is no longer covered by the sealing clasp 18 and the sealing clasp 18 is no longer connected to the slide 10 via the driver 32 . The screw heads 22 of the guide 20 of the sealing clasp 18 are displaced during the movement in the x-direction into the short arms of the F-shaped guide 20 formed in the x-direction, so that the sealing clasp 18 rests on the screw heads 22 in the guide 20 . The screw drive 24 is designed to be comparable to the screw drive 13 of the slide 10 described above. The threaded rod 27 is movably mounted with the end of the threaded rod 27 opposite the interface 28 in a connection 29 in the y-direction. For this purpose, the threaded rod 27 is guided in a slot 31 formed in the housing 30 of the connection 29 in such a way that when the threaded rod 27 is moved in the bushing 26 along the x-axis, force can be transmitted to the sealing clasp 18 and, at the same time, a movement of the sealing clasp 18 in the y-direction is possible. The bushing 26 is fixed in a bushing 25 as described above. The various positions of the slide 10 and the sealing clip 18 are defined by stops (not shown), the stops being able to be arranged on the one hand in the guides 11, 20 or in the screw drives 13, 24. In a lower position of the sealing clasp 18, i.e. in the position in which the sealing clasp 18 seals the groove 5 in the pipe section 4, the position of the sealing clasp 18 in the guide 20 is also detected by a sensor 23, such as a limit switch, which is arranged in the example shown in the guide 20. The sensor 23 can also be arranged at another suitable point in the system. The sensor signal can be transmitted to a controller (not shown) of the MRI system 40 so that it can only be put into operation when the groove 5 in the valve arrangement 1 is tightly closed by the sealing clip 18 . The signals can be transmitted to the controller of the MRT system 40 via a cable 37 which is routed through a cable bushing 38 through the wall of the housing 2 . The cable bushing 38 is designed to be helium-tight and covered by a baffle plate 39 in the event of a failure. The baffle plate 39 is connected to the housing 2 in such a way that the cable 37 runs between the housing 2 and the baffle plate 39 after the cable bushing 38 . This prevents the liquid helium escaping through the cable bushing 38 in the event of a fault from hitting a person doing maintenance or other parts in the technical area 47 . The helium first hits the baffle plate 39, where it immediately evaporates, with the light helium evaporating upwards.

2 B shows a valve arrangement 1 according to the invention for a magnetic resonance tomography system 40, the valve arrangement 1 being shown in a closed position. The structure of the valve assembly 1 is identical to that in FIG 2a with the difference that the sealing clip 18 is in a parking position, ie it rests on the screw heads 22 in the two horizontal recesses 21 of the F-shaped guide 20 . The slider 10 has been lowered by the screw drive 13 to such an extent that it dips into the groove 5 of the pipe section 4 to such an extent that it is completely closed by the slider 10 . No helium can flow from the MRT system 40 into the second partial area 56 of the quench tube 50 or get into the MRT system 40 in the opposite direction. To detect the position of the slider 10 in the closed position, a further sensor 12, such as a limit switch, is arranged in the immediate vicinity of the guide 11 of the slider 10, which is designed as an L-plate. This detects the position of the slide 10 and transmits the signal that the slide 10 is closed to the control of the MRT system 40. The MRT system 40 can then no longer be started up and the interface 49 between the flanges 6 can also be separated , 48, ie between the valve assembly 1 and the first portion 55 of the quench tube 50, is possible without risk.

The installation positions of the sensors 12 and 23 shown in the figure are to be understood as examples. Of course, other installation positions and additional sensors are also conceivable. In particular, it is also advantageous to interrogate subgroups of the sensors in combination in order to obtain reliable information about the state of the valve arrangement 1.

3 shows a detailed view of the valve assembly 1, in which the already in the 1 explained driver 32 is shown in detail. The driver 32 includes a recess 33 in the slide 10, into which two screw heads 34 arranged on the sealing clip 18 can immerse. If the sealing clip 18 is replaced by the screw drive 24, as in 2a already explained, moved up to the slide 10 in the negative x-direction, the screw heads 34, which are arranged in the area of the lever 35 of the sealing clip 18, appear, as in FIG 3 shown, in the recess 33 a. As a result, when the slider 10 moves along the y-axis, as in FIG 2a described, the sealing clip 18 moves. This can be positioned on the outside of the pipe section 4 with the help of the screw drive of the slide 10 in the open position for sealing the groove 5 with the spring 19 .

the 4a shows a further embodiment of a valve arrangement 1 which comprises a one-piece valve 36 . In the illustrated first closed position of the valve 36, a first area 62 of a one-piece slide 60 closes the pipe section 4 in the housing 2 of the valve drive 1. No helium can flow through the valve arrangement 1. An identical to the one in the 2a and the 2 B trained screw drive 13 moves the slide 60 to a second position in which the valve 36, as in the 4b shown, is shown in an open position. In this open position, a second area 63 of the slide 60 is arranged with an opening 61 corresponding to the inner diameter of the pipe section 4 such that the inner surfaces of the opening 61 and the pipe section 4 form a continuous surface, i.e. without edges or shoulders. The helium from the MRI system 40 can be vented via the second portion of the quench tube 50 . The sensors 12 and 23 for detecting the first and the second position have the same function as that in FIG 2a and 2 B described sensors 12, 23.

Reference List

1

valve assembly

2

Housing

3

lid

4

pipe section

5

groove

6

flange

7

Weld

8th

recess

9

flange

10

Slider y-axis

11

Guide slider y-axis

12

sensor

13

Screw drive slider y-axis

14

Implementation y drive

15

Bushing y-drive

16

Threaded rod y-drive

17

Interface y drive

18

Sealing clip x-axis

19

Feather

20

Guide sealing clip x-axis

21

recess

22

screw heads

23

sensor

24

Screw drive x-axis

25

Implementation x drive

26

Socket x drive

27

Threaded rod x drive

28

Interface x drive

29

Connection x-drive

30

Housing

31

Long hole

32

driver

33

recess

34

screw heads

35

lever

36

Valve

37

Cable

38

grommet

39

flapper

40

Magnetic resonance imaging system

41

area of study

42

electromagnetic coil

43

encapsulation

44

Support

45

drain valve

46

execution

47

technical area

48

flange

49

interface

50

quench tube

51

interface

52

flange

53

exhaust air

54

helium

55

first section

56

second section

60

slider

61

opening

62

first area

63

second area

Claims (14)

Quench tube (50) for a magnetic resonance tomography system (40), characterized in that the quench tube (50) comprises a valve arrangement (1) for shutting off the quench tube (50). Quench tube (50) after claim 1 , characterized in that the valve arrangement (1) comprises a valve (36) for closing the quench tube (50). Quench tube (50) after claim 2 , characterized in that the valve (36) is made in one piece. Quench tube (50) after claim 2 , characterized in that the valve (36) is formed in two parts. Quench tube (50) according to one of claims 2 until 4 , characterized in that the valve (36) comprises a slide (10, 60). Quench tube (50) according to one of Claims 4 or 5 , characterized in that a first part of the valve (36) is designed as a slide (10) for closing the quench tube (50). Quench tube (50) according to one of Claims 4 until 6 , characterized in that a second part (18) of the valve for sealing a for the slide (10) formed groove (5) in the quench tube (50) is formed. Quench tube (50) after claim 7 , characterized in that the second part (18) is designed such that the seal of the groove (5) of the quench tube (50) is helium-tight. Quench tube (50) according to one of Claims 4 until 8th , characterized in that the first part (10) is at least temporarily connected to the second part (18) of the valve (36) via a driver (32). Quench tube (50) after claim 9 , characterized in that the two parts (10, 18) connected via the driver (32) can be moved by a first drive (13). Quench tube (50) after claim 9 or 10 , characterized in that the second part (18) by a second drive (24) perpendicular to the movement of the first drive (13) relative to the first part (10) are movable. Quench tube (50) according to one of claims 2 until 9 , characterized in that the valve arrangement (1) comprises sensors (12, 23) for detecting at least a first and a second position of the valve (36). Quench tube (50) according to one of the preceding claims, characterized in that the valve arrangement (1) is designed to be helium-tight. Magnetic resonance tomography system (40) with a quench tube (50) according to one of the preceding claims.

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