阅读说明：本技术 具有紧急失超的磁共振成像系统 (Magnetic resonance imaging system with emergency quench ) 是由 P·R·哈维 E·让 T·詹内斯肯斯 于 2018-05-08 设计创作，主要内容包括：本发明涉及一种具有紧急失超的磁共振成像(MRI)系统。根据本发明,磁共振成像系统(1)包括：具有用于生成磁场的绕组(3)的超导磁体(2)、紧急按钮(4),以及被耦合到所述磁体(2)和所述紧急按钮(4)的用于控制所述磁体(2)的逻辑电路(5),其中,所述磁体(2)能分别在超导状态和正常导电状态下操作,并且所述紧急按钮(4)和所述逻辑电路(5)以如下方式进行配置：当所述磁体(2)在所述超导状态下操作时,由用户以预定义的第一方式致动所述紧急按钮(4)来启动使所述磁场斜降并同时使存储在所述磁体(2)的所述绕组(3)中的能量耗散到外部耗散设备(6),并且由用户以不同于所述第一方式的预定义的第二方式致动所述紧急按钮(4)来启动通过以下操作使所述磁场失超：加热所述磁体(2)的所述绕组(3)的至少部分,引起存储在所述磁体(2)的所述绕组(3)中的能量作为额外热量耗散到所述磁体(2)。以这种方式,在必须消除磁场的情况下,提供了一种容易且可靠的方式来控制MRI系统(1)的超导磁体(2)。(The present invention relates to a Magnetic Resonance Imaging (MRI) system with emergency quench. According to the invention, a magnetic resonance imaging system (1) comprises: -a superconducting magnet (2) having windings (3) for generating a magnetic field, -an emergency button (4), and-a logic circuit (5) coupled to the magnet (2) and the emergency button (4) for controlling the magnet (2), wherein the magnet (2) is operable in a superconducting state and a normally conductive state, respectively, and the emergency button (4) and the logic circuit (5) are configured in the following manner: actuating by a user the emergency button (4) in a predefined first manner to initiate ramping down the magnetic field and simultaneously dissipating energy stored in the windings (3) of the magnet (2) to an external dissipation device (6) when the magnet (2) is operating in the superconducting state, and actuating by a user the emergency button (4) in a predefined second manner different from the first manner to initiate quenching the magnetic field by: heating at least part of the windings (3) of the magnet (2), causing energy stored in the windings (3) of the magnet (2) to dissipate to the magnet (2) as additional heat. In this way, an easy and reliable way of controlling a superconducting magnet (2) of an MRI system (1) is provided in case the magnetic field has to be eliminated.)

1. A magnetic resonance imaging system (1) comprising: a superconducting magnet (2) having windings (3) for generating a magnetic field, an emergency button (4), and a logic circuit (5) coupled to the magnet (2) and the emergency button (4) for controlling the magnet (2), wherein,

the magnet (2) is operable in a superconducting state and a normally conducting state, respectively, and

the emergency button (4) and the logic circuit (5) are configured in such a way that: actuating by a user the emergency button (4) in a predefined first manner to initiate ramping down the magnetic field and simultaneously dissipating energy stored in the windings (3) of the magnet (2) to an external dissipation device (6) when the magnet (2) is operating in the superconducting state, and actuating by a user the emergency button (4) in a predefined second manner different from the first manner to initiate quenching the magnetic field by: heating at least part of the windings (3) of the magnet (2), causing energy stored in the windings (3) of the magnet (2) to dissipate to the magnet (2) as additional heat.

2. The magnetic resonance imaging system (1) as defined in claim 1, wherein a cryogen (7) for cooling the magnet (2) is provided for achieving the superconducting state of the magnet (2), and

actuating the emergency button (4) by the user in the first manner initiates ramping down the magnetic field while avoiding evaporating the refrigerant (7), and actuating the emergency button (4) by the user in the second manner initiates quenching the magnetic field while at least partially evaporating the refrigerant (7).

3. The magnetic resonance imaging system (1) as claimed in claim 1 or 2, wherein the actuation of the panic button (4) by the user in the first manner is a first user action and the actuation of the panic button (4) by the user in the second manner comprises a combination of the first and second user actions.

4. The magnetic resonance imaging system (1) as defined in claim 3, wherein the second user action is a repetition of the first user action within a predetermined time period.

5. The magnetic resonance imaging system (1) according to any one of the preceding claims, wherein the actuation of the panic button (4) by the user in the first manner is a single press action and the actuation of the panic button (4) by the user in the second manner is a double press action having a first press action and a second press action, the second press action occurring within a predetermined time period after the first press action.

6. A method for controlling operation of a superconducting magnet (2) of a magnetic resonance imaging system (1),

the magnet (2) is operable in a superconducting state and a normally conducting state, respectively, and comprises windings (3) for generating a magnetic field, and

the magnetic resonance imaging system (1) comprises an emergency button (4) which can be activated by a predefined first and second modality,

the method comprises the following steps:

operating the magnet (2) in the superconducting state, and

ramping down the magnetic field and simultaneously dissipating energy stored in the windings of the magnet to an external dissipation device (6) in response to actuation of the emergency button (4) by a user in the predefined first manner, or

Quenching the magnetic field in response to actuation of the emergency button (4) by a user in the predefined second manner different from the first manner by: heating at least part of the windings (3) of the magnet (2), causing energy stored in the windings (3) of the magnet (2) to dissipate to the magnet (2) as additional heat.

7. The method according to claim 6, wherein the magnet (2) is cooled by a cryogen (7) to achieve the superconducting state of the magnet (2), and

in response to actuation of the emergency button (4) by the user in the first manner to ramp down the magnetic field while avoiding evaporation of the refrigerant (7), or

Quenching the magnetic field and simultaneously at least partially evaporating the refrigerant (7) in response to actuation of the emergency button (4) by the user in the second manner.

8. The method according to claim 6 or 7, wherein actuating the emergency button (4) by the user in the first manner is a first user action, and actuating the emergency button (4) by the user in the second manner comprises a combination of the first user action and a second user action.

9. The method of claim 8, wherein the second user action is a repetition of the first user action within a predetermined time period.

10. The method according to any one of claims 6 to 9, wherein the actuation of the emergency button (4) by the user in the first manner is a single press action, and the actuation of the emergency button (4) by the user in the second manner is a double press action having a first press action and a second press action, and the second press action occurs within a predetermined time period after the first press action.

11. A non-transitory computer readable medium for controlling the operation of a superconducting magnet (2) of a magnetic resonance imaging system (1), the magnet (2) being operable in a superconducting state and a normally conductive state, respectively, and comprising windings (3) for generating a magnetic field, and the magnetic resonance imaging system (1) comprising an emergency button (4), the non-transitory computer readable medium comprising instructions stored thereon which, when executed on a processor, perform the steps of:

operating the magnet (2) in the superconducting state, and

in response to actuation of the emergency button (4) by a user in a predefined first manner to ramp down the magnetic field and simultaneously dissipate energy stored in the windings of the magnet (2) to an external dissipation device (6), or

Quenching the magnetic field in response to actuation of the emergency button (4) by a user in a predefined second manner different from the first manner by: heating at least part of the windings (3) of the magnet (2), causing energy stored in the windings (3) of the magnet (2) to dissipate to the magnet (2) as additional heat.

12. The non-transitory computer-readable medium of claim 11, wherein actuating the emergency button (4) by the user in the first manner is a first user action, and actuating the emergency button (4) by the user in the second manner comprises a combination of the first user action and a second user action.

13. The non-transitory computer-readable medium of claim 11 or 12, wherein the second user action is a repetition of the first user action within a predetermined time period.

14. The non-transitory computer readable medium according to any one of claims 11 to 13, wherein the actuation of the emergency button (4) by the user in the first manner is a single press action, and the actuation of the emergency button (4) by the user in the second manner is a double press action having a first press action and a second press action, and the second press action occurs within a predetermined time period after the first press action.

Technical Field

The invention relates to a magnetic resonance imaging system comprising: a superconducting magnet having windings for generating a magnetic field, an emergency button, and logic circuitry coupled to the magnet and the emergency button for controlling the magnet, and to a method and non-transitory computer readable medium for controlling operation of a superconducting magnet of a magnetic resonance imaging system.

Background

For Magnetic Resonance Imaging (MRI) systems with superconducting magnets, it is possible to ramp down the magnetic field of the magnet and simultaneously dissipate the energy stored in the magnet to an external dissipation device (such as an electrical load). This can prevent the magnet from "warming up" and allow the magnet to re-ramp almost immediately without requiring an additional cooling period or without causing substantial loss of refrigerant (typically liquid helium) to the magnet.

In addition, virtually all superconducting magnets of an MRI system include a quench capability to rapidly remove the magnetic field in an emergency. Typically, superconducting MRI systems are provided with one or more quench buttons that a user can press in an emergency. In the event of a quench, the portion of the magnet that is normally superconducting winding is intentionally heated, causing the superconductor to switch to a normally conductive state. This state diffuses rapidly throughout the magnet and the energy stored in the magnet is dissipated as heat in the magnetic conductors and internal structures. If the magnet contains liquid helium as the cryogen, this helium will typically evaporate and be expelled from the magnet. During a quench, the magnet can heat up and take a significant amount of additional time to cool down before the magnetic field can ramp up again. Thus, quench is an expensive and time consuming event.

However, it is not necessary to quench the magnet every emergency, and a somewhat slower controlled ramp down will be equally effective as explained further above. Therefore, in such a case, it would be beneficial to ramp the magnet down and dissipate energy to the outside of the magnet, which would enable the magnet to be ramped up again quickly once the emergency situation is resolved.

A superconducting magnet is an electromagnet made of coils/windings of superconducting wire. To achieve superconductivity, the coil must be cooled to a low temperature during operation. In its superconducting state, the resistance of the wire is substantially zero and the current injected into the wire will flow without dissipation. When the ends of the current carrying superconducting wire loop are closed (connected), the current continues to flow without (or very slowly) decaying. The superconducting state allows current to continue to flow with "zero" dissipation without the need for an external power source. Common wires can also carry large currents (depending on thickness), but also generate a large amount of heat, which is impractical for high-field MRI applications. The superconducting wire realizes a compact magnet having a high magnetic field and requiring no continuous supply of external energy to maintain the magnetic field. Therefore, a superconducting magnet is used in an MRI system in a hospital that requires a very strong magnetic field to examine a human body.

During operation, the magnet coil must cool below its critical temperature (i.e., the temperature at which the winding material changes from a normal resistance state and becomes a superconductor). Two types of cooling (i.e., liquid cooling or mechanical cooling) are typically used to maintain the magnet windings at a temperature sufficient to maintain superconductivity. When liquid cooling is applied, liquid helium is typically used as the refrigerant. However, some superconducting systems can also use two stages of mechanical refrigeration for cooling.

A superconducting magnet with liquid cooling that recondenses helium gas to liquid helium is commonly referred to as a zero-evaporation (ZBO) magnet. Helium gas formed by the evaporation of liquid helium in a superconducting magnet helium pressure vessel flows through passages in a recondenser cooled by a cryocooler to recondense the helium gas back to liquid helium to return to the liquid helium bath in the pressure vessel.

Disclosure of Invention

It is an object of the present invention to provide an easy and reliable way to control a superconducting magnet of an MRI system in case a magnetic field has to be eliminated.

This object is solved by the subject matter of the independent claims. Preferred embodiments are described in the dependent claims.

Thus, according to the present invention, there is provided a Magnetic Resonance Imaging (MRI) system, the system comprising: a superconducting magnet having windings for generating a magnetic field, an emergency button, and a logic circuit coupled to the magnet and the emergency button for controlling the magnet, wherein

The magnets are operable in a superconducting state and a normally conductive state, respectively, and

the emergency button and the logic circuit are configured in the following manner: actuating, by a user, the emergency button in a predefined first manner to initiate ramping down the magnetic field and simultaneously dissipating energy stored in the windings of the magnet to an external dissipation device when the magnet is operating in the superconducting state, and actuating, by a user, the emergency button in a predefined second manner different from the first manner to initiate quenching the magnetic field by: heating at least a portion of the windings of the magnet, causing energy stored in the windings of the magnet to dissipate to the magnet as additional heat.

The invention therefore offers the possibility of: in an emergency or other situation, the user of the MRI system can quickly choose between an immediate quench of the magnet or a controlled ramp down of the magnet, which has the advantage that there is little risk of damage to the magnet and enables the magnet to be ramped up again quickly once the emergency situation is resolved. According to a preferred embodiment of the invention, this selection is made according to the number of times the emergency button is actuated, as will be explained in more detail below.

The invention is generally applicable to all superconducting magnet types, including ZBO magnets and so-called encapsulated or helium-free magnets. In ZBO magnets, quenching the magnet still involves uncontrolled evaporation of liquid helium. Furthermore, in both ZBO magnets and helium-free magnets, quench dissipates the magnetic energy stored in the coil windings. This will heat the coil windings and require re-cooling of the magnet windings before the magnet is again ramped, which may take hours or even days. Controlled heating of the coil windings may also result in mechanical damage to the coil windings and their supporting structure. It would also be possible to retrofit existing MRI systems if a method were also provided that enables a controlled ramp down by allowing the magnet to dissipate energy to the outside.

According to a preferred embodiment of the invention, if a cryogen for cooling the magnet is provided for achieving the superconducting state of the magnet, actuating the emergency button by the user in the first manner initiates ramping down the magnetic field while avoiding evaporating the cryogen, and actuating the emergency button by the user in the second manner initiates quenching the magnetic field while evaporating the cryogen at least partially.

In order to actuate the emergency button in a first way by a user and in a second way by a user, there are generally many different types of user actions possible, respectively. Although the button can be actuated completely differently in the first and second ways, respectively, according to a preferred embodiment of the invention, actuating the emergency button by the user in the first way is a first user action and actuating the emergency button by the user in the second way comprises a combination of the first and second user actions. This means that according to this preferred embodiment of the invention the second way of actuating the emergency button comprises at least two first user actions. However, the first user action can also be repeated multiple times, or with the addition of another user operation. Preferably, the second user action is a repetition of the first user action within a predetermined time period.

Additionally, the actuation button may include touching, rotating, or tilting the emergency button in a different manner. However, according to a preferred embodiment of the invention, the actuation of the emergency button by the user in the first manner is a single press action, and the actuation of the emergency button by the user in the second manner is a double press action having a first press action and a second press action, the second press action occurring within a predetermined time period after the first press action. This method is very easy to reliably shut down the MRI system in the intended manner.

The invention also relates to a method for controlling the operation of a superconducting magnet of a magnetic resonance imaging system,

the magnets are operable in a superconducting state and a normally conducting state, respectively, and comprise windings for generating a magnetic field, and

the magnetic resonance imaging system comprises an emergency button,

the method comprises the following steps:

operating the magnet in the superconducting state, and

in response to actuation of the emergency button by a user in a predefined first manner to ramp down the magnetic field and simultaneously dissipate energy stored in the windings of the magnet to an external dissipating device, or

Quenching the magnetic field in response to actuation of the emergency button by a user in a predefined second manner different from the first manner by: heating at least a portion of the windings of the magnet, causing energy stored in the windings of the magnet to dissipate to the magnet as additional heat.

Furthermore, the invention relates to a non-transitory computer readable medium for controlling the operation of a superconducting magnet of a magnetic resonance imaging system, the magnet being operable in a superconducting state and a normally conductive state, respectively, and comprising windings for generating a magnetic field, and the magnetic resonance imaging system comprising an emergency button, the non-transitory computer readable medium comprising instructions stored thereon which, when executed on a processor, perform the steps of:

operating the magnet in the superconducting state, and

in response to actuation of the emergency button by a user in a predefined first manner to ramp down the magnetic field and simultaneously dissipate energy stored in the windings of the magnet to an external dissipating device, or

Quenching the magnetic field in response to actuation of the emergency button by a user in a predefined second manner different from the first manner by: heating at least a portion of the windings of the magnet, causing energy stored in the windings of the magnet to dissipate to the magnet as additional heat.

The preferred embodiments further described above are similarly applicable to the method and non-transitory computer readable medium, respectively, for controlling the operation of a superconducting magnet of a magnetic resonance imaging system.

Drawings

These and other aspects of the invention are apparent from and will be elucidated with reference to the embodiments described hereinafter. Such embodiments, however, do not necessarily represent the full scope of the invention, and reference is made herein to the claims for interpreting the scope of the invention.

In the drawings:

FIG. 1 schematically depicts an MRI system according to a preferred embodiment of the present invention, and

fig. 2 depicts a flow chart of a method according to a preferred embodiment of the invention.

List of reference numerals

1 MRI system

2 magnet

3 windings of magnets

4 Emergency button

5 logic circuit

6 external dissipation device

7 refrigerant

Detailed Description

As schematically depicted in fig. 1, according to a preferred embodiment of the present invention, a magnetic resonance imaging system 1 is provided, the magnetic resonance imaging system 1 comprising: a superconducting magnet 2 having windings 3 for generating a magnetic field, an emergency button 4, and a logic circuit 5 coupled to the magnet and the emergency button for controlling the magnet 2. The magnet 2 is capable of operating in a superconducting state and a normally conductive state, respectively. In the situation depicted in fig. 1, the magnet 2 is operated in its superconducting state, which is required for normal operation of the MRI system 1. Therefore, according to the present embodiment of the invention, the winding 3 for the magnet 2 is cooled by the refrigerant 7, and the refrigerant 7 is liquid helium. In the event of liquid helium evaporation, an emergency vent line 8 is provided to vent excess helium gas to the atmosphere. In addition, an electrical load is provided as an external dissipation device 6, which can be used to dissipate the heat generated in the windings 3 of the magnet 2 when the magnet 2 is ramped down in a controlled manner.

According to a preferred embodiment of the invention, the emergency button 4 and the logic circuit 5 are configured such that the emergency button 4 is actuated in a first manner or a second manner, respectively, to obtain different results. The emergency button 4 is designed such that it is mounted within the reach of a user of the MRI system 1 and can be actuated by a pressing action, for example with the palm of the hand.

As depicted in the flow chart of fig. 2, it is determined whether the panic button 4 is pushed, i.e. whether it is the first push action. If such a first pushing action is determined, it is further checked whether it is a predefined time t after the first pushing action_pDefining a second pushing action. If this is not the case, i.e. if the user has actuated the emergency button 4 with a single push action, a regular and controlled ramp down of the magnetic field of the magnet 2 is performed. This means that the energy stored in the windings 3 of the magnet 2 is dissipated to the external dissipation device 6 and thus "heating" of the magnet 2 is avoided. However, if at a predefined time t after the first pushing action_pA second push action is determined, i.e. an immediate quench of the magnetic field of the magnet 2 is initiated if the user has actuated the emergency button 4 with two push actions. This means that at least part of the windings 3 of the magnet 2 is heated, thereby causing storage inThe energy in the windings 3 of the magnet 2 is dissipated to the magnet 2 as additional heat. This, though, has the following disadvantages: during this procedure, the magnet 2 may be damaged and it takes extra time to cool the magnet 2 before the magnet 2 can be ramped up again, but in this way the magnetic field can be eliminated very quickly in a dangerous situation.

While the invention has been illustrated and described in detail in the drawings and foregoing description, such illustration and description are to be considered illustrative or exemplary and not restrictive; the invention is not limited to the disclosed embodiments. Other variations to the disclosed embodiments can be understood and effected by those skilled in the art in practicing the claimed invention, from a study of the drawings, the disclosure, and the appended claims. In the claims, the word "comprising" does not exclude other elements or steps, and the word "a" or "an" does not exclude a plurality. Although some measures are recited in mutually different dependent claims, this does not indicate that a combination of these measures cannot be used to advantage. Any reference signs in the claims shall not be construed as limiting the scope.