Method and System for Controlling a Ramping Process of a Magnetic Resonance Imaging Device

Abstract

Techniques are provided for controlling a ramping process of a superconducting magnet of a magnetic resonance imaging device comprising the steps of: acquiring an information indicating a status of a cryocooler configured for cooling of the superconducting magnet via an interface, acquiring an information on a parameter of the superconducting magnet via an interface, determining an operational status of the magnetic resonance imaging device in dependence of the information indicating the status of the cryocooler and/or the information on the parameter of the superconducting magnet via a processing unit and providing a control signal via a control unit, wherein the control signal is configured to control the ramping process of the superconducting magnet. The disclosure also relates to a magnetic resonance imaging system comprising a control unit configured to provide a control signal for controlling the ramping process of the superconducting magnet.

Claims

1. A computer-implemented method for controlling a ramping process of a superconducting magnet of a magnetic resonance imaging device, comprising: acquiring, via an interface, cryocooler status data indicative of a status of a cryocooler configured to cool the superconducting magnet; acquiring, via the interface, superconducting magnet data indicative of a parameter of the superconducting magnet; determining, via processing circuitry, an operational status of the magnetic resonance imaging device based upon the cryocooler status data and/or the superconducting magnet data; and providing, via a controller, a control signal configured to control the ramping process of the superconducting magnet, wherein the control signal is provided based upon the determined operational status of the magnetic resonance imaging device and the cryocooler status data.

2. The method according to claim 1, wherein the act of acquiring the superconducting magnet data comprises: acquiring a value of an electrical property and/or a physical property of the superconducting magnet via at least one sensor.

3. The method according to claim 2, wherein the superconducting magnet data acquired via the at least one sensor comprises a voltage, a current, a magnetic field, and/or a temperature of the superconducting magnet.

4. The method according to claim 1, wherein the act of acquiring the cryocooler status data comprises: acquiring data indicative of a capacity of the cryocooler for maintaining a predefined cooling condition.

5. The method according to claim 4, wherein the act of acquiring the cryocooler status data comprises: acquiring a level of a cryogen within a fluid reservoir of the cryocooler via a sensor.

6. The method according to claim 1, wherein the act of acquiring the cryocooler status data comprises: acquiring a turn-off time of a compressor of the cryocooler, and wherein the act of determining the operational status of the magnetic resonance imaging device comprises: correlating the turn-off time of the compressor with at least one reference time.

7. The method according to claim 6, wherein the at least one reference time comprises a first reference time and a second reference time, and wherein the act of determining the operational status of the magnetic resonance imaging device comprises: correlating the turn-off time of the compressor with the first reference time and the second reference time.

8. The method according to claim 1, wherein the act of determining the operational status of the magnetic resonance imaging device comprises: assessing a readiness of the superconducting magnet to perform a magnetic resonance imaging measurement based upon the superconducting magnet data.

9. The method according to claim 8, wherein when the operational status of the magnetic resonance imaging device is assessed as being ready to perform the magnetic resonance imaging measurement, the act of providing the control signal comprises: providing the control signal for ramping down the superconducting magnet.

10. The method according to claim 8, wherein the act of determining the operational status of the magnetic resonance imaging device comprises: when a present ramping process is detected based upon the superconducting magnet data, the magnetic resonance imaging device is assessed as being unready to perform the magnetic resonance imaging measurement.

11. The method according to claim 1, wherein the act of acquiring the superconducting magnet data comprises acquiring a voltage of the superconducting magnet via at least one sensor, and wherein the act of determining the operational status of the magnetic resonance imaging device comprises: assessing the superconducting magnet to be ramping down when the voltage of the superconducting magnet is less than a predefined value.

12. The method according to claim 1, wherein the act of acquiring the superconducting magnet data comprises acquiring a voltage of the superconducting magnet via at least one sensor, and wherein the act of determining the operational status of the magnetic resonance imaging device comprises: assessing the superconducting magnet to be ramping up when the voltage of the superconducting magnet exceeds a predefined value.

13. The method according to claim 1, wherein the act of providing the control signal comprises: providing the control signal for interrupting a ramping up of the superconducting magnet.

14. A magnetic resonance imaging system, comprising: a magnetic resonance imaging device; a superconducting magnet; an interface configured to receive cryocooler status data indicative of a status of a cryocooler and superconducting magnet data indicative of a parameter of the superconducting magnet; processing circuitry configured to determine an operational status of the magnetic resonance imaging device based upon the cryocooler status data and/or the superconducting magnet data; and a controller configured to provide a control signal configured to control a ramping process of the superconducting magnet, wherein the control signal is provided based upon the determined operational status of the magnetic resonance imaging device and the cryocooler status data.

15. A non-transitory computer-readable medium having instructions stored thereon that, when executed by processing circuitry of a magnetic resonance imaging device, causes the magnetic resonance imaging device to control a ramping process of a superconducting magnet of the magnetic resonance imaging device by: acquiring cryocooler status data indicative of a status of a cryocooler configured to cool the superconducting magnet; acquiring superconducting magnet data indicative of a parameter of the superconducting magnet; determining an operational status of the magnetic resonance imaging device based upon the status data and/or the superconducting magnet data; and providing a control signal configured to control the ramping process of the superconducting magnet, wherein the control signal is provided based upon the determined operational status of the magnetic resonance imaging device and the cryocooler status data.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0077] Further advantages and details of the present disclosure may be recognized from the embodiments described below as well as the drawings. The figures show:

[0078] FIG. 1 illustrates a schematic representation of a magnetic resonance imaging system according to one or more embodiments of the disclosure;

[0079] FIG. 2 illustrates a flow diagram of a method according to one or more embodiments of the disclosure; and

[0080] FIG. 3 illustrates a flow chart of a method according to one or more embodiments of the disclosure.

DETAILED DESCRIPTION OF THE DISCLOSURE

[0081] FIG. 1 shows an embodiment of a magnetic resonance imaging system 11 according to one or more embodiments of the disclosure. The magnetic resonance imaging system 11 comprises a magnetic resonance imaging device 13 with a static field magnet 17 that provides a homogenous, static magnetic field 18 (B0 field). The static magnetic field 18 comprises an isocenter 38 and a cylindrical imaging region 36 for receiving a patient 15. The imaging region 36 is surrounded by the magnet arrangement 30 in a circumferential direction. The patient support 16 is configured to transport the patient 15 into the imaging region 36. For instance, the patient support 16 may transport a diagnostically relevant region of the patient 15 into an imaging volume defined by the isocenter 38 of the magnetic resonance imaging device 13. In an embodiment, the magnetic resonance imaging device 13 is screened from an environment by a housing shell 31.

[0082] The magnetic resonance imaging device 13 further comprises a gradient magnet arrangement 19 configured to provide magnetic gradient fields used for spatial encoding of magnetic resonance signals acquired during a magnetic resonance imaging measurement. The gradient magnet arrangement 19 is activated or controlled by a gradient controller 28 via an appropriate current signal.

[0083] The magnetic resonance imaging device 13 further comprises a radiofrequency antenna 20 (body coil), which may be integrated into the magnetic resonance imaging device 13. The radiofrequency antenna 20 is operated via a radiofrequency controller 29 that controls the radiofrequency antenna 20 to generate a high frequency magnetic field and emit radiofrequency excitation pulses into an examination space, which is essentially formed by the imaging region 36. The magnetic resonance imaging system 11 may further comprise a local coil 21, which is positioned on or in proximity to the diagnostically relevant region of the patient 15. The local coil 21 may be configured to emit radiofrequency excitation pulses into the patient 15 and/or receive magnetic resonance signals from the patient 15. It is conceivable that the local coil 21 is controlled via the radiofrequency controller 29.

[0084] The magnetic resonance imaging system 11 further comprises a control unit (also referred to herein as control circuitry or a controller) 23 configured to control the magnetic resonance imaging system 11. The control unit 23 may comprise a processing unit (also referred to herein one or more processors or processing circuitry) 24 configured to process magnetic resonance signals and reconstruct magnetic resonance images. The processing unit 24 may also be configured to process input from a user of the magnetic resonance imaging device 13 and/or provide an output to a user. For this purpose, the processing unit 24 and/or the control unit 23 can be connected to a display unit (also referred to herein as a display) 25 and an input unit (also referred to herein as input circuitry or a user interface) 26 via a suitable signal connection. For a preparation of a magnetic resonance imaging measurement, preparatory information, such as imaging parameters or patient information, can be provided to the user via the display unit 25. The input unit 26 may be configured to receive information and/or imaging parameters from the user. The display unit 25 and the input unit 26 may also be implemented as a combined interface, such as a touch interface.

[0085] The magnetic resonance imaging system 11 further comprises a cryocooler 32 configured to cool coils of a superconducting magnet in the magnet arrangement 30 below a predefined temperature in the range of a superconducting temperature of the superconducting magnet. The cryocooler 32 may comprise a compressor 33 supplying pressurized gas to the cryocooler 32. According to the embodiment shown in FIG. 1, the cryocooler 32 also comprises a thermal connection 34 configured to transport heat energy out of the magnet arrangement 30. The thermal connection 34 may be implemented as a coldhead comprising one or more cooling stages. In a preferred embodiment, at least one cooling stage of the coldhead is thermally coupled to the coils of the superconducting magnet.

[0086] In the embodiment shown in FIG. 1, the cryocooler 32 comprises a signal connection 22b with an interface 40 of the magnetic resonance imaging system 11. The signal connection 22b may be configured for transmitting information from the cryocooler 32 to the magnetic resonance imaging device 13, and vice versa. Such information may, for example, comprise control signals, but also information indicating a turn-off time of the compressor 33 of the cryocooler 32. The signal connection 22b may be implemented as a wired connection or a wireless connection.

[0087] According to the embodiment shown in FIG. 1, the magnetic resonance imaging system 11 comprises a sensor 31 configured to determine an electrical voltage of a coil of the superconducting magnet. The electrical voltage of a coil of the superconducting magnet may be transmitted to the control unit 23 of the magnetic resonance imaging device 13 via the signal connection 22a. It is also conceivable that the sensor 31 is coupled to the interface 40. The magnetic resonance imaging system 11 may comprise another sensor and/or additional sensors according to an embodiment described above. For example, the magnetic resonance imaging may comprise a temperature sensor for assessing a temperature level of a cryogen within the cryocooler 32 and/or a pressure sensor configured to determine a pressure level of a pressure line and/or a buffer tank connected to the compressor 33 (not shown).

[0088] Of course, the magnetic resonance imaging system 11 may comprise further components that magnetic resonance imaging systems usually exhibit. The general operation of a magnetic resonance imaging system 11 is known to those skilled in the art, so a more detailed description is not deemed necessary.

[0089] FIG. 2 illustrates a flow diagram of a method according to one or more embodiments of the disclosure, which includes e.g. a computer-implemented method for controlling a ramping process of a superconducting magnet of a magnetic resonance imaging device 13.

[0090] In a step S1, information indicating a status of a cryocooler 32 configured for cooling of the superconducting magnet is acquired via an interface 40. In an embodiment, the information indicating the status of the cryocooler 32 comprises a turn-off time, e. g. a time value quantifying a period of time that has lapsed since the compressor 33 has lastly ceased to operate. The information indicating the status of the cryocooler 32 may be received by the interface 40 via signal connection 22b.

[0091] A step S2 comprises acquiring information on a parameter of the superconducting magnet via an interface. For example, the information on the parameter of the superconducting magnet may be acquired by the at least one sensor 31 (see FIG. 1) configured to determine an electrical voltage of a coil of the superconducting magnet. The information on the parameter of the superconducting magnet may then be transmitted to the control unit 23 via the signal connection 22a. The interface for receiving the information on the parameter of the superconducting magnet may be incorporated within the control unit 23 (not shown in FIG. 1). However, the sensor may also transmit the information on the parameter of the superconducting magnet to the interface 40, which is connected to the control unit 23.

[0092] According to an embodiment, acquiring the information on the parameter of the superconducting magnet comprises acquiring a value of an electrical property and/or a physical property of the superconducting magnet via the at least one sensor 31. The information on the parameter of the superconducting magnet acquired via the at least one sensor 31 may comprise, for example, an electrical voltage, an electrical current, a magnetic field, and/or a temperature of the superconducting magnet.

[0093] In a step S3, an operational status of the magnetic resonance imaging device is determined in dependence of the information indicating the status of the cryocooler 32 and/or the information on the parameter of the superconducting magnet via a processing unit 24. In one example, a readiness of the magnetic resonance imaging device 13 to perform a magnetic resonance imaging measurement is assessed at least in dependence of the information on the parameter of the superconducting magnet. It is conceivable that the operational status of the magnetic resonance imaging device 13 is also determined based on the information indicating the status of the cryocooler 32. For example, if the turn-off time of the compressor 33 is determined to be lower than a reference time, the magnetic resonance imaging device 13 may be estimated to be fully operational and the method may repeat from step S1.

[0094] In one embodiment, determining the operational status of the magnetic resonance imaging device 13 comprises correlating the turn-off time of the compressor 33 with at least one reference time. In an embodiment, determining the operational status of the magnetic resonance imaging device 13 comprises correlating the turn-off time of the compressor 33 with at least a first reference time and a second reference time.

[0095] For example, the second reference time relates to a turn-off time of the compressor 33 where temperature problems in the superconducting magnet are expected when performing a magnetic resonance imaging measurement. Thus, in case the turn-off time of the compressor 33 exceeds the second reference time, a control signal may be provided via the control unit 23 to intentionally ramp down the superconducting magnet and to avoid an unintended ramp-down (or emergency ramp down) during a magnetic resonance imaging measurement.

[0096] The first reference time may relate to a turn-off time of the compressor 33 where temperature problems in the superconducting magnet can be dismissed. For example, the superconducting magnet may be able to perform one or more magnetic resonance imaging measurements or imaging sequences without causing an unintended ramp-down. However, the first reference time may also relate to a turn-off time of the compressor 33 that allows performing a magnetic resonance imaging measurement only under certain conditions. Such conditions may comprise a restriction of a number of imaging sequences to be performed, but also a restriction to a specific magnetic resonance imaging measurement or a set of specific magnetic resonance imaging measurements.

[0097] According to a further embodiment, determining the operational status of magnetic resonance imaging device 13 comprises assessing a readiness of the superconducting magnet for performing a magnetic resonance imaging measurement in dependence of the information on the parameter of the superconducting magnet. For example, the superconducting magnet may be assessed as being ready for measurement if the electrical current, the electrical voltage, the temperature, and/or the magnetic field of the superconducting magnet lie within predefined value ranges. In an embodiment, if the temperature of the superconducting magnet is below or equal to a superconducting temperature and/or the electrical voltage of a coil of the superconducting magnet corresponds to an operating voltage of the superconducting magnet, the operational status of the magnetic resonance imaging device 13 is assessed as “ready”.

[0098] Determining the operational status of the magnetic resonance imaging device 13 may also comprise detecting a present ramping process in dependence of the information on the parameter of the superconducting magnet, wherein the magnetic resonance imaging device 13 is assessed as being unready for performing a magnetic resonance measurement. In an embodiment, the operational status of the magnetic resonance imaging device 13 may be determined as being “unready” if the electrical voltage of a coil of the superconducting magnet lies within a predefined value range indicating a ramping process of the superconducting magnet.

[0099] For example, the operational status of the magnetic resonance imaging device 13 comprises assessing the superconducting magnet to be ramping down if the electrical voltage of the superconducting magnet is below a predefined value, e.g. below 100 mV. In contrast, the superconducting magnet may be assessed as ramping up when the electrical voltage of the superconducting magnet exceeds a predefined value, e.g. 100 mV.

[0100] According to a step S4, a control signal is provided via a control unit 23, wherein the control signal is configured to control the ramping process of the superconducting magnet, and wherein the control signal depends on the determined operational status of the magnetic resonance imaging device 13 and on the information indicating the status of the cryocooler 32. Depending on the operational status of the magnetic resonance imaging device 13, the control signal may be configured to initiate a ramp-up process or a ramp-down process of the superconducting magnet. It is conceivable that the control signal is directed at an electronic circuit configured for energizing and/or de-energizing the superconducting magnet. However, the control signal may also be transmitted to a control unit of the cryocooler 32 to align the cooling of the superconducting magnet with the ramping process. The control signal may be transmitted via the signal connection 22b or any other suitable signal connection.

[0101] In one embodiment, providing the control signal comprises providing a signal for ramping down the superconducting magnet if the operational status of the magnetic resonance imaging device 13 is assessed as being ready for performing a magnetic resonance measurement. In a further embodiment, providing the control signal comprises providing a signal for interrupting a ramp-up of the superconducting magnet.

[0102] FIG. 3 illustrates a flow chart of a method according to one or more embodiments of the disclosure.

[0103] In step A, the turn-off time of the compressor 33 is received via the interface 40. Step A may also comprise triggering or initiating the acquisition of the turn-off time of the compressor 33 via the interface 40.

[0104] In step a), determining of the operational status of the magnetic resonance imaging device 13 comprises determining a difference between the turn-off time of the compressor 33 and at least one reference time. If the at least one reference time is exceeded (“T”), the method progresses to step b). Otherwise, steps A and a) are repeated (“F”).

[0105] In step b), determining the operational status of the magnetic resonance imaging device 13 comprises assessing a readiness of the superconducting magnet of the magnet assembly 30 for performing a magnetic resonance imaging measurement in dependence of an electrical property of the superconducting magnet. For this purpose, an electrical voltage of the superconducting magnet is acquired via sensor 31 and transmitted to an interface of the control unit 23 and/or processing unit 24. If the operational status of the magnetic resonance imaging device 13 is assessed as being “ready” (“T”), the control unit 23 provides a control signal to ramp down the superconducting magnet, as shown in step B. Otherwise, the method progresses to step c).

[0106] In step c), determining the operational status of the magnetic resonance imaging device 13 comprises determining a difference between the acquired electrical voltage and a first predefined value of 100 mV. If the acquired electrical voltage exceeds the first predefined value (“T1”), the superconducting magnet is ramping up. Consequently, in step C, a control signal is provided to interrupt the ramping process of the superconducting magnet. In case the acquired electrical voltage is below the first predefined value (“F1”), the method proceeds to step d).

[0107] In step d), determining the operational status of the magnetic resonance imaging device 13 comprises determining a difference between the acquired electrical voltage and a second predefined value of 100 mV. If the acquired electrical voltage is below the second predefined value (“T2”), the superconducting magnet is ramping down. Thus, a control signal for ramping down the magnet may already be provided and is maintained in step E. Otherwise, the electrical voltage is situated between the first predefined value and the second predefined value (“F2”). In this case, no action is required as the superconducting magnet is not in an operational state and no ramping process is occurring. The inventive method starts over from A, as indicated in step D.

[0108] It shall be understood that the embodiments described above are to be recognized as examples. Individual embodiments may be extended by features of other embodiments. The sequence of the steps of the methods are to be understood as exemplary. The individual steps may be carried out in a different order and/or overlap partially or completely in time.

[0109] The various components described herein may be referred to as “units.” Such components may be implemented via any suitable combination of hardware and/or software components as applicable and/or known to achieve their intended respective functionality. This may include mechanical and/or electrical components, processors, processing circuitry, or other suitable hardware components, in addition to or instead of those discussed herein. Such components may be configured to operate independently, or configured to execute instructions or computer programs that are stored on a suitable computer readable medium. Regardless of the particular implementation, such units, as applicable and relevant, may alternatively be referred to herein as “circuitry,” “controllers,” “processors,” or “processing circuitry,” or alternatively as noted herein.