Magnetic resonance imaging system and power supply control method

Abstract

To improve inspection throughput in a magnetic resonance imaging system.SOLUTION: A magnetic resonance imaging system, as a power supply source, can switch a normal power supply and an uninterruptible power supply, and comprises a cooling part, an imaging system, a switch, and a switch control part. The cooling part cools a superconducting coil generating a magnetostatic field. The imaging system relates to imaging of a subject using the magnetostatic field. The switch cuts off power supply to the imaging system from the power supply source. The switch control part controls the switch on the basis of information on the start of power supply from the uninterruptible power supply. The switch control part controls the switch so as to cut off power supply to the imaging system when power failure in the normal power supply continues for a first time.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The embodiments disclosed in this specification and the drawings relate to a magnetic resonance imaging system and a method for controlling a power supply. [Background technology]

[0002] Conventionally, in a magnetic resonance imaging apparatus (hereinafter referred to as an MRI (Magnetic Resonance Imaging) apparatus) having a superconducting static magnetic field magnet (superconducting coil), in order to prepare for a power outage, for example, a power supply (emergency power supply) for dealing with a power outage is arranged separately from a commercial power supply in a hospital facility, and a quench can be prevented by switching the power supply from the commercial power supply to the emergency power supply in the event of a power outage. However, when the emergency power supply is used, the power capacity required for the emergency power supply may be several times larger than the rated current due to the generation of an inrush current (for example, several times the rated current) in the system transformer of the MRI apparatus and the operation of the entire MRI apparatus. This causes a problem of increased costs for the emergency power supply to ensure its operation.

[0003] For these reasons, when the emergency power supply is in operation, for example, a power saving mode that cuts off the power supply to the imaging system in the MRI system, or an uninterruptible power supply (hereinafter referred to as UPS) is provided between the MRI apparatus, the commercial power supply, and the MRI apparatus to prevent excitation inrush current due to residual magnetic flux in the system transformer. However, if the power saving mode is activated by a signal issued by the UPS due to a momentary power outage or voltage drop, the examination is interrupted, which causes a problem of reduced examination throughput. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2013-172148 Summary of the Invention [Problem to be solved by the invention]

[0005] One of the problems to be solved by the embodiments disclosed in this specification and the drawings is to improve the throughput of examinations in a magnetic resonance imaging system. However, the problems to be solved by the embodiments disclosed in this specification and the drawings are not limited to the above problem. Problems corresponding to the effects of each configuration shown in the embodiments described later can also be positioned as other problems. [Means for solving the problem]

[0006] A magnetic resonance imaging system according to an embodiment can be switched between a normal power source and an uninterruptible power source, and includes a cooling unit, an imaging system, a switch, and a switch control unit. The cooling unit is a component for cooling a superconducting coil that generates a static magnetic field, and includes components necessary for these components to operate, such as a chiller required for water-cooling the components. The imaging system is related to imaging of a subject using the static magnetic field. The switch cuts off the power supply from the power source to the imaging system. The switch control unit controls the switch based on information on the start of power supply from the uninterruptible power source. When a power outage in the normal power source continues for a first time, the switch control unit controls the switch to cut off the power supply to the imaging system, enabling operation in low power consumption. [Brief description of the drawings]

[0007] [Figure 1] FIG. 1 is a block diagram showing an example of a magnetic resonance imaging system in an embodiment when an imaging system power supply switch is in an ON state (closed). [Diagram 2] FIG. 2 is a block diagram showing an example of an MRI system when an imaging system power supply switch is in an OFF state (open) in the embodiment. [Diagram 3] FIG. 3 is a flowchart showing an example of a procedure of a switching control process according to the embodiment. [Figure 4]FIG. 4 is a diagram showing an example of a relationship between the output power (also referred to as apparent power) of a UPS according to an embodiment and a backup time during which the UPS can operate. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] Hereinafter, with reference to the drawings, an embodiment of a magnetic resonance imaging system and a power supply control method capable of switching between a normal power source and an uninterruptible power source as a power supply source will be described in detail. Fig. 1 is a block diagram showing an example of a magnetic resonance imaging system (hereinafter referred to as an MRI (Magnetic Resonance Imaging) system) 1 in an ON state (when blocked) of a switch (hereinafter referred to as an imaging system power supply switch) SW for switching on and off the power supply to an imaging system 11 related to imaging of a subject using a static magnetic field. Note that the technical idea of ​​this embodiment may be realized by an MRI device 10 having a switch control circuit 7, or an MRI device 10 having an uninterruptible power supply (hereinafter referred to as an UPS) 5 and a switch control circuit 7.

[0009] The MRI system 1 includes a UPS 5, a switch control circuit 7, and an MRI apparatus 10. The UPS 5 is provided, for example, between the normal power supply 3 and the MRI apparatus 10 in a power supply line from the normal power supply 3 to the MRI apparatus 10. The UPS 5 may be provided outside the MRI system 1. In this case, the MRI system 1 includes the switch control circuit 7 and the MRI apparatus 10.

[0010] The normal power supply 3 corresponds to a facility power supply in a hospital or the like where the MRI system 1 is installed, i.e., a commercial power supply. The normal power supply 3 supplies power to the MRI system 1. At this time, the power supplied from the normal power supply 3 is supplied to all units of the MRI apparatus 10, such as the imaging system 11 and the static magnetic field generating unit 15, via a system transformer 13 in the MRI apparatus 10. The power supplied from the normal power supply 3 is also supplied to other units not involved in cooling the superconducting coil 152, such as a console and a bed (not shown). The power supplied from the normal power supply 3 is also used to charge the UPS 5.

[0011] The UPS 5 has a secondary battery and a power supply monitoring device 51. The secondary battery supplies power to the MRI apparatus 10 during a power outage, including a momentary power outage (also called a momentary interruption) in the normal power supply 3. The secondary battery is charged by the supply of power from the normal power supply 3 when the normal power supply 3 is not out of power. The power supply monitoring device 51 functions as a monitor that monitors the state of power supply to the MRI apparatus 10 by the normal power supply 3.

[0012] The power supply monitoring device 51 outputs information on the start of power supply from the UPS 5 to the MRI apparatus 10 (hereinafter referred to as power supply start information) to the switch control circuit 7. The power supply start information is, for example, the start point of a power outage, i.e., the time when a power outage occurs (hereinafter referred to as power outage occurrence time), and is information indicating the occurrence of a power outage. The power supply monitoring device 51 also outputs information indicating the start of power restoration of the normal power supply 3 after a power outage of the normal power supply 3 (hereinafter referred to as power restoration start information) to the switch control circuit 7. The power restoration start information is, for example, the time when the normal power supply 3 recovers from a power outage (hereinafter referred to as power restoration time), i.e., the start point of power restoration, and is information indicating the restoration of the normal power supply 3.

[0013] The MRI system 1 may be electrically connected to an emergency power supply, which is a power supply independent of the normal power supply 3, via a power supply system changeover switch that changes the power supply system. The emergency power supply has, for example, an engine and a generator that generates three-phase AC. In this case, the MRI system 1 can switch between the normal power supply 3 and the emergency power supply as the power supply source by changing the power supply system changeover switch. In this case, the MRI system 1 may have a power supply system changeover switch and an emergency power supply. The power supply system changeover switch changes the connection destination of the power supply to the MRI apparatus 10 between the normal power supply 3 and the emergency power supply based on information indicating the occurrence of a power outage output from the power supply monitoring device 51.

[0014] For example, when a power outage occurs in the normal power supply 3, the power system changeover switch changes the connection of the power supply to the MRI apparatus 10 from the normal power supply 3 to the emergency power supply. During the duration of the power outage of the normal power supply 3, power supply to the MRI apparatus 10 is performed by the UPS 5 during the period from the power outage of the normal power supply 3 to the completion of switching to the emergency power supply. Furthermore, when the normal power supply 3 is restored, the power system changeover switch changes the connection of the power supply to the MRI apparatus 10 from the emergency power supply to the normal power supply 3. At this time, the normal power supply 3 supplies power to the MRI system. In addition, the UPS 5 charges the secondary battery by the power supply from the normal power supply 3.

[0015] Fig. 2 is a block diagram showing an example of the MRI system 1 when the imaging system power supply switch SW is in the OFF state (open). The difference from Fig. 1 is that the imaging system power supply switch SW is open. The imaging system power supply switch SW is opened by control of the switch control circuit 7, for example, when a power outage of the utility power supply 3 continues for a first time t1, that is, when the first time t1 has elapsed from the time when the power outage occurred during the power outage period of the utility power supply 3. The first time t1 will be described later.

[0016] The switch control circuit 7 controls the imaging system power supply switch SW based on power supply start information from the UPS 5, i.e., power supply start information. For example, when a power outage in the utility power supply 3 continues for a first time t1, the switch control circuit 7 controls the imaging system power supply switch SW to cut off the power supply to the imaging system 11. This enables the MRI system 1 to operate in a power-saving manner. Specifically, when the first time t1 has elapsed from the time when the power outage occurred during the power outage period of the utility power supply 3, the switch control circuit 7 supplies a current to the contact drive coil CC of the relay 17. At this time, the imaging system power supply switch SW is opened by the operation of the movable contact of the relay 17.

[0017] As a result, the UPS 5 supplies power to a cooling unit and the imaging system 11 described below while the power outage of the utility power supply 3 continues for the first time t1, and supplies power only to the cooling unit after the power outage of the utility power supply 3 continues for the first time t1. The switch control circuit 7 corresponds to a switch control unit, and is realized by, for example, a processor. The switch control circuit 7 may be mounted on the UPS 5. The cooling unit is a component for cooling the superconducting coil 152 that generates a static magnetic field, and includes components necessary for the operation of these components, such as a chiller necessary for water-cooling the components.

[0018] The switch control circuit 7 controls the imaging system power supply switch SW based on the power restoration start information. For example, after the imaging system power supply switch SW cuts off the power supply to the imaging system 11, i.e., after the imaging system power supply switch SW is opened, if the power restoration of the normal power supply 3 continues for a second time t2, the switch control circuit 7 further controls the imaging system power supply switch SW so that power is supplied to the imaging system 11.

[0019] Specifically, when the power restoration continues for a second time t2 from the power restoration time, the switch control circuit 7 stops supplying current to the contact driving coil CC of the relay 17. At this time, the movable contact of the imaging system power supply switch SW moves to a closed position where it comes into contact with the fixed contact due to the biasing by the elastic body of the relay 17, that is, the biasing of the movable contact to the fixed contact. As a result, the imaging system power supply switch SW is closed. As a result, the utility power supply 3 supplies power to the cooling unit while the power restoration of the utility power supply 3 continues for the second time t2, and supplies power to the cooling unit and the imaging system 11 after the power restoration of the utility power supply 3 continues for the second time t2. The second time t2 will be described later. The process related to the control of the relay 17 by the switch control circuit 7 (hereinafter referred to as switching control process) will be described in detail later.

[0020] The first time t1 and the second time t2 may be set analogically based on the inductance L of the contact drive coil CC related to the imaging system power supply switch SW (hereinafter referred to as coil inductance) and the resistance R of the cable from the switch control circuit 7 to the contact drive coil CC and the contact drive coil CC (hereinafter referred to as switch-related resistance). Specifically, the first time t1 is set so that, assuming that the time from the power supply stop to the operation stop in the MRI apparatus 10 is τa, the contact drive coil operation time τb determined by the time constant of the ratio L / R of the coil inductance L to the switch-related resistance R is greater than τa.

[0021] The time τa from when the power supply to the MRI apparatus 10 is stopped to when the operation is stopped is determined by a time constant that indicates the degree of response of the power supply ON / OFF in the units subsequent to the system transformer 13 in the MRI apparatus 10. Also, the contact drive coil operation time τb determined by the time constant L / R corresponds to the time constant that indicates the degree of response of the switching operation in the imaging system power supply switch SW. In other words, the first time t1 is set to be greater than τa (t1>τa).

[0022] When the switch control circuit 7 is realized by an analog circuit, the analog circuit is appropriately configured by selecting the ratio L / R of inductance to resistance in the switch control circuit 7, the operating point of the contact driving coil CC, and the constants of the coil and resistance. At this time, the first time t1 and the second time t2 are approximately equal. For this reason, when a power outage occurs in the normal power supply 3, for example, the imaging system power supply switch SW is opened after the voltage in the MRI apparatus 10 drops to a predetermined voltage. The second time t2 may be shorter than the first time t1. That is, the first time t1 may be longer than the second time t2.

[0023] The first time t1 is, for example, 1 / 4 cycle or more and 1 minute or less of the frequency of the voltage in the utility power supply 3. That is, the first time t1 includes a time corresponding to a momentary interruption defined as a sudden voltage drop lasting for a period of 1 / 2 cycle to several seconds at a certain point of the power system of the MRI apparatus 10. In other words, the first time t1 includes a duration of a short power outage that exceeds the momentary interruption. Note that the first time t1 is not limited to the above-mentioned 1 minute, and may be 1 minute or more. In addition, the first time t1 and the second time t2 may be digitally controlled so that they can be arbitrarily set by the user according to the individual difference of τa in the MRI apparatus 10. That is, the first time t1 and the second time t2 can be set to desired values ​​by digital control.

[0024] The MRI apparatus 10 includes an imaging system (imaging device) 11, a system transformer 13, a static magnetic field generating unit 15, and a relay 17. The static magnetic field generating unit 15 includes a cooling vessel 151 having a superconducting coil 152 related to the generation of the static magnetic field, a refrigerator 153, and a refrigerator monitor 159. The cooling vessel 151, the refrigerator 153, and the refrigerator monitor 159 configure a cooling section (cooling device) that cools the superconducting coil 152 that generates the static magnetic field. That is, the cooling section includes a refrigerator 153 that cools a refrigerant related to cooling the superconducting coil 152. The refrigerant is, for example, helium.

[0025] The imaging system 11 is related to imaging of a subject. That is, the imaging system 11 has various units related to the imaging. The various units have, for example, a gradient magnetic field power supply 111 for generating a gradient magnetic field for position identification, a gradient magnetic field coil, a transmission circuit equipped with an RF amplifier 113 for supplying energy for causing a magnetic resonance phenomenon, a transmission coil, a receiving coil, a receiving circuit, a sequence control circuit, a bed, and a computer system equipped with a reconstruction unit 115 for imaging a signal obtained as a result of the magnetic resonance phenomenon. Each component of the imaging system 11 will be described later.

[0026] The system transformer 13 has a function (hereinafter referred to as a power distribution function) of distributing the power supplied from the normal power supply 3 or the UPS 5 to the static magnetic field generating unit 15 and the relay 17. The system transformer 13 supplies the power supplied from the normal power supply 3 or the UPS 5 to the static magnetic field generating unit 15 and the relay 17 by the power distribution function.

[0027] The static magnetic field generating unit 15 has a superconducting coil 152 formed in a hollow, approximately cylindrical shape, and generates a static magnetic field in the internal space. The static magnetic field generated by the static magnetic field generating unit 15 is generated by a superconducting magnet. The superconducting magnet is realized by supplying a current to the superconducting coil 152 in the cooling vessel 151 in a superconducting state. The cooling vessel 151 is formed in an approximately cylindrical shape and is housed within the cylindrical wall of a vacuum vessel (not shown). As a general example, the cooling vessel 151 houses liquid helium and the superconducting coil 152 within the cylindrical wall to keep the inside of the vessel at a sufficiently low temperature. In the cooling vessel 151, liquid helium and helium gas obtained by vaporizing the liquid helium are in equilibrium.

[0028] A heater (not shown) is provided inside the cooling container 151. The heater warms and vaporizes the helium in the cooling container 151, and adjusts the pressure in the cooling container 151. The pressure is adjusted, for example, to prevent unintended air from flowing into the cooling container 151. If the helium gas in the cooling container 151 is cooled excessively, the proportion of liquid helium in the cooling container 151 increases, and the pressure in the cooling container 151 decreases. If the pressure in the cooling container 151 decreases and becomes negative, air will flow into the cooling container 151. The heater is controlled by the refrigerator monitor 159 to keep the pressure in the cooling container 151 within a preset range, and warms the helium in the cooling container 151.

[0029] The refrigerator 153 cools the refrigerant contained in the cooling container 151. The refrigerator 153 has a compressor 155, a cold head 157, a supply pipe, a discharge pipe, a vent valve, an intake valve, a buffer tank, and the like (not shown). The refrigerator 153 also has a water-cooling device that water-cools the refrigerant or an air-cooling device that air-cools the refrigerant. The water-cooling device continuously cools the refrigerant in the refrigerator 153 by using water. The water-cooling device corresponds to a cooling water circulation device and is also called a chiller that exchanges heat with outside air. The air-cooling device and the chiller can be existing devices, so a description of the air-cooling device and the chiller will be omitted.

[0030] Compressor 155 compresses refrigerant gas such as helium gas by, for example, a motor, and supplies the refrigerant gas in a high-pressure state to cold head 157 via a supply pipe. The motor is, for example, inverter-driven. Compressor 155 also recovers the refrigerant gas expanded inside cold head 157 via a discharge pipe. Compressor 155 also connects to a buffer tank filled with refrigerant gas via a vent valve and an intake valve. The buffer tank is filled with refrigerant gas. Compressor 155 exhausts the refrigerant gas to the buffer tank via the vent valve. Compressor 155 draws in the refrigerant gas filled in the buffer tank via the intake valve.

[0031] Cold head 157 expands the high-pressure refrigerant gas supplied via a supply pipe, and cools the refrigerant in cooling container 151. In this way, cold head 157 cools the refrigerant to a temperature equal to or lower than the boiling point of the refrigerant. When cooling container 151 is cooled to a certain level or more, the helium gas in cooling container 151 is recondensed into liquid helium. Note that, although FIGS. 1 and 2 show an example in which one cold head 157 is installed in cooling container 151, the number of cold heads 157 is not limited to one, and multiple cold heads may be installed.

[0032] The vent valve and the intake valve are provided on a pipe connecting the compressor 155 and the buffer tank. The vent valve exhausts the refrigerant gas in the compressor 155 to the buffer tank in accordance with instructions from the refrigerator monitoring device 159. As the refrigerant gas in the compressor 155 is exhausted, the pressure of the refrigerant gas supplied from the compressor 155 to the cold head 157 decreases. The intake valve supplies the refrigerant gas to be filled in the buffer tank to the compressor 155 in accordance with instructions from the refrigerator monitoring device 159. As the refrigerant gas is supplied to the compressor 155, the pressure of the refrigerant gas supplied from the compressor 155 to the cold head 157 increases.

[0033] So far, we have described an example in which helium (He) is required as a refrigerant for cooling the magnet, but this embodiment can also be applied to an MRI system 1 that has a magnet that uses a conduction cooling method that does not use a refrigerant, or a magnet that uses an extremely small amount of refrigerant for cooling the magnet.

[0034] Refrigeration unit monitoring device 159 monitors the refrigerant in refrigerator 153 and cooling container 151. For example, refrigerator monitoring device 159 monitors the pressure inside cooling container 151 and controls the heater so that the pressure inside cooling container 151 is within a preset range. Refrigeration unit monitoring device 159 monitors the pressure of the refrigerant gas supplied from compressor 155 to cold head 157, and controls the vent valve and intake valve so that the pressure is within a predetermined range.

[0035] The relay 17 is provided between the system transformer 13 and a plurality of units related to power supply in the imaging system 11. That is, the relay 17 is provided before the power supply line to a plurality of units such as the gradient magnetic field power supply 111 that are not involved in cooling the static magnetic field generating unit 15. The relay 17 has an imaging system power supply switch SW and a contact driving coil CC that functions as an electromagnet. The relay 17 is also called a relay.

[0036] The relay 17 opens the imaging system power supply switch SW in accordance with the current output from the switch control circuit 7. The imaging system power supply switch SW cuts off the power supply from the power supply source to the imaging system 11. The imaging system power supply switch SW is, for example, a normally closed contact. That is, when no current is output from the switch control circuit 7, the movable contact in the imaging system power supply switch SW is urged to a fixed contact by, for example, an elastic body, and is in a closed state.

[0037] The contact drive coil CC generates a magnetic field when supplied with current from the switch control circuit 7. The generation of the magnetic field opens the contacts of the imaging system power supply switch SW. When the imaging system power supply switch SW is opened and the supply of current from the switch control circuit 7 is cut off, the magnetic field generated by the contact drive coil CC disappears, and the imaging system power supply switch SW becomes closed.

[0038] 1 and 2, the multiple units in the imaging system 11 are described as a gradient magnetic field power supply 111, an RF amplifier 113, and a reconstruction unit 115, but are not limited thereto, and may further include other units related to the imaging system 11, such as a bed. As shown in FIG. 1, when power is supplied from the normal power supply 3, the imaging system power supply switch SW is closed (blocked). Therefore, power is supplied from the normal power supply 3 to all units in the MRI apparatus 10.

[0039] On the other hand, when the power supply from the utility power supply 3 stops, that is, when a power outage occurs, the imaging system power supply switch SW is opened as shown in Fig. 2 by the control of the switch control circuit 7 based on the power supply start information sent from the UPS 5 after the first time t1 has elapsed from the time when the power outage occurred. As a result, when the utility power supply 3 fails, the power supplied from the UPS 5 is supplied only to the units required for cooling the superconducting coil 152.

[0040] The components included in the imaging system 11 will be briefly described below.

[0041] The gradient magnetic field coil is a coil formed in a hollow, approximately cylindrical shape, and is disposed on the inner surface side of the cylindrical cooling vessel 151. The gradient magnetic field coil generates a gradient magnetic field whose magnetic field strength changes along the mutually orthogonal X-, Y-, and Z-axes.

[0042] The gradient magnetic field power supply 111 supplies current to the gradient magnetic field coil under the control of a sequence control circuit in the MRI apparatus 10 using power supplied via the system transformer 13 and the imaging system power supply switch SW.

[0043] The transmission coil receives a supply of RF (Radio Frequency) pulses from a transmission circuit and generates a high-frequency magnetic field in an imaging space in the MRI apparatus .

[0044] The transmission circuit transmits an RF pulse corresponding to the Larmor frequency to the transmission coil under the control of the sequence control circuit. The transmission circuit includes, for example, an oscillator, a phase selection unit, a frequency conversion unit, an amplitude modulation unit, and an RF amplifier 113. The oscillator generates an RF pulse with a resonance frequency specific to the target atomic nucleus in the static magnetic field. The phase selection unit selects the phase of the RF pulse generated by the oscillator. The frequency conversion unit converts the frequency of the RF pulse output from the phase selection unit. The amplitude modulation unit modulates the amplitude of the RF pulse output from the frequency conversion unit according to, for example, a sinc function. The RF amplifier 113 amplifies the RF pulse output from the amplitude modulation unit using power supplied via the system transformer 13 and the imaging system power supply switch SW, and supplies the amplified RF pulse to the transmission coil.

[0045] The receiving coil is disposed inside the gradient coil and receives MR signals emitted from the subject under the influence of the high frequency magnetic field. The receiving coil outputs the received MR signals to a receiving circuit. Note that the receiving coil may also be used as a transmitting coil.

[0046] The receiving circuit converts the analog MR signal output from the receiving coil into analog-to-digital (AD) data, and transmits the generated MR data to the sequence control circuit.

[0047] The sequence control circuit drives the gradient magnetic field power supply 111, the transmission circuit, and the reception circuit based on sequence information transmitted from the computer system, thereby imaging the subject. The sequence information is information that defines a procedure for performing imaging. When the sequence control circuit drives the gradient magnetic field power supply 111, the transmission circuit, and the reception circuit to image the subject, and receives MR data from the reception circuit, the sequence control circuit transfers the received MR data to the computer system. The sequence control circuit is realized by, for example, a processor.

[0048] The bed includes a top plate on which a subject is placed. The bed is composed of actuators such as various motors that drive the top plate and the bed, and a power transmission unit that transmits the power generated by the actuators to the movable parts. The bed and the top plate are moved in the longitudinal direction and the up-down direction of the top plate under the control of a computer system.

[0049] The computer system performs overall control of the MRI apparatus 10, generates MR images, etc. The computer system includes, for example, a network interface, a storage circuit, a processing circuit, an input interface, and a display.

[0050] The storage circuitry stores the MR data received by the network interface, the k-space data arranged in the k-space by a processing circuitry described later, the image data generated by the processing circuitry, etc. The storage circuitry is realized by, for example, a semiconductor memory element such as a RAM (Random Access Memory) or a flash memory, a hard disk, or an optical disk.

[0051] The input interface accepts various instructions (e.g., a power-on instruction) and information input from an operator. The input interface is realized by, for example, a trackball, a switch button, a mouse, a keyboard, a touchpad that performs an input operation by touching the operation surface, a touch screen in which a display screen and a touchpad are integrated, a non-contact input circuit using an optical sensor, and a voice input circuit. The input interface is connected to a processing circuit, and converts an input operation received from an operator into an electric signal and outputs it to the processing circuit. Note that, in this specification, the input interface is not limited to an interface having physical operation parts such as a mouse and a keyboard. For example, an electric signal processing circuit that receives an electric signal corresponding to an input operation from an external input device provided separately from the computer system and outputs the electric signal to a control circuit is also included as an example of an input interface.

[0052] Under the control of the processing circuit, the display displays various GUIs (Graphical User Interfaces), magnetic resonance images generated by the processing circuit, etc. The display is, for example, a display device such as a liquid crystal display.

[0053] The processing circuitry controls the entire MRI apparatus 10. More specifically, the processing circuitry includes, for example, an imaging control function and a reconstruction function. The processing circuitry that realizes the reconstruction function is an example of the reconstruction unit 115. Each function, such as the imaging control function and the reconstruction function, is stored in the storage circuitry in the form of a program executable by a computer. The processing circuitry is a processor. For example, the processing circuitry realizes a function corresponding to each program by reading and executing the program from the storage circuitry. In other words, the processing circuitry in a state in which each program has been read has each function, such as the imaging control function and the reconstruction function.

[0054] In the above description, an example has been described in which the "processor" reads out a program corresponding to each function from a storage circuit and executes it, but the embodiment is not limited to this. The term "processor" refers to a circuit such as a CPU, a GPU (Graphics Processing Unit), an Application Specific Integrated Circuit (ASIC), a programmable logic device (e.g., a Simple Programmable Logic Device (SPLD), a Complex Programmable Logic Device (CPLD), and a Field Programmable Gate Array (FPGA)).

[0055] For example, if the processor is a CPU, the processor realizes the function by reading and executing a program stored in a storage circuit. On the other hand, if the processor is an ASIC, instead of storing a program in a storage circuit, the function is directly incorporated as a logic circuit in the circuit of the processor. Note that each processor in this embodiment is not limited to being configured as a single circuit for each processor, but may be configured as a single processor by combining multiple independent circuits to realize the function. Also, although a single storage circuit has been described as storing a program corresponding to each processing function, multiple storage circuits may be distributed and arranged, and the processing circuit may read the corresponding program from each storage circuit.

[0056] The imaging control function performs imaging of magnetic resonance images by controlling each part of the MRI apparatus 10. More specifically, the imaging control function performs generation of sequence information, collection of MR data, and the like.

[0057] The reconstruction function generates k-space data and a magnetic resonance image using power supplied via the system transformer 13 and the imaging system power supply switch SW. The reconstruction function performs image reconstruction processing on the generated k-space data using a two-dimensional or three-dimensional Fourier transform to generate a magnetic resonance image. The reconstruction function stores the generated magnetic resonance image in, for example, a storage circuit.

[0058] The switching control process executed by the MRI system 1 of the present embodiment configured as above will be described with reference to FIG. 3. FIG. 3 is a flowchart showing an example of the procedure of the switching control process according to the embodiment. Before the implementation of this flowchart, the utility power supply 3 is in a non-powered state. Also, no current is supplied to the relay 17, and the movable contact of the imaging system power supply switch SW is biased to the fixed contact by an elastic body. That is, the imaging system power supply switch SW is in a normally closed contact state, i.e., in a blocked state. The process in this flowchart is constantly executed, for example, when the MRI system 1 is installed and power supply to the MRI device 10 is started.

[0059] (Switching control processing) (Step S301) If the power supply monitoring device 51 in the UPS 5 does not detect a power outage in the normal power supply 3 (NO in step S301), this step is repeated. If the power supply monitoring device 51 detects a power outage in the normal power supply 3 (YES in step S301), the process of step S302 is executed. Upon detection of the power outage, the power supply monitoring device 51 outputs power supply start information, i.e., the time when the power outage occurred, to the switch control circuit 7.

[0060] (Step S302) The UPS 5 starts supplying power to the MRI apparatus 10. As a result, power is supplied from the UPS 5 to the MRI apparatus 10. That is, the power supply source to the MRI apparatus 10 is switched from the utility power supply 3 to the UPS 5 when the utility power supply 3 fails.

[0061] (Step S303) If the power outage has not continued for the first time t1 from the power outage occurrence time (No in step S303), the process of step S304 is executed. If the power outage has continued for the first time t1 from the power outage occurrence time (Yes in step S303), the process of step S306 is executed. For example, when the switch control circuit 7 is realized by a processor, the switch control circuit 7 determines whether or not the power outage has continued for the first time t1 from the power outage occurrence time. If the power outage has not continued for the first time t1 from the power outage occurrence time (Yes in step S303), the switch control circuit 7 supplies a current to the contact drive coil CC of the relay 17.

[0062] (Step S304) If the power supply monitoring device 51 in the UPS 5 does not detect the restoration of power to the normal power supply 3 (NO in step S304), the process of step S303 is executed. If the power supply monitoring device 51 detects the restoration of power to the normal power supply 3 (YES in step S304), the process of step S305 is executed.

[0063] (Step S305) When the power restoration is detected in step S304, the power supply source to the MRI apparatus 10 is switched from the UPS 5 to the utility power source 3. At this time, the UPS 5 starts charging the secondary battery by supplying power from the utility power source 3. After this step, the process of step S301 is executed.

[0064] (Step S306) The imaging system power supply switch SW is opened. Specifically, when a current is supplied from the switch control circuit 7 to the relay 17, a current flows through the contact drive coil CC. This causes the contact drive coil CC to generate a magnetic field as an electromagnet and attract the movable contact. Operation of the movable contact opens the imaging system power supply switch SW, cutting off the power supply from the power supply source to the imaging system 11. In other words, power from the UPS 5 is supplied only to the cooling section.

[0065] (Step S307) If the power supply monitoring device 51 does not detect the restoration of power to the normal power supply 3 (NO in step S307), this step is repeated. If the power supply monitoring device 51 detects the restoration of power to the normal power supply 3 (YES in step S307), the process of step S308 is executed. Upon detecting the restoration of power, the power supply monitoring device 51 outputs power restoration start information, i.e., the power restoration time, to the switch control circuit 7.

[0066] (Step S308) If power restoration has not continued from the power restoration time through the second time t2 (No in step S308), the process of step S309 is executed. If power restoration has continued from the power restoration time through the second time t2 (Yes in step S308), the process of step S310 is executed. For example, when the switch control circuit 7 is realized by a processor, the switch control circuit 7 determines whether power restoration has continued from the power restoration occurrence time through the second time t2. If power restoration has continued from the power restoration time through the second time t2 (Yes in step S308), the switch control circuit 7 stops the supply of current to the relay 17.

[0067] (Step S309) If the power supply monitoring device 51 in the UPS 5 does not detect a power outage in the utility power supply 3 (NO in step S309), the process proceeds to step S308. If the power supply monitoring device 51 detects a power outage in the utility power supply 3 (YES in step S309), the process proceeds to step S307.

[0068] (Step S310) The power supply source to the MRI apparatus 10 is switched from the UPS 5 to the utility power supply 3. At this time, the UPS 5 starts charging the secondary battery by supplying power from the utility power supply 3.

[0069] (Step S311) The imaging system power supply switch SW is closed. Specifically, when the current supplied from the switch control circuit 7 to the relay 17 is stopped, the current supply to the contact drive coil CC is stopped. As a result, the magnetic field generated by the contact drive coil CC disappears. At this time, the movable contact of the imaging system power supply switch SW is brought into contact with the fixed setting by the bias of the elastic body. As a result, the imaging system power supply switch SW is closed, and the power supply to the imaging system 11 is resumed. In this step, the power from the normal power supply 3 is supplied to the cooling unit and the imaging system 11. In this step, the switching control process shown in FIG. 3 is ended. More specifically, the processes of steps S301 to S311 are repeatedly executed until the MRI system 1 is discarded. The operation of the MRI system 1 in steps S306 to S311 corresponds to a power saving operation.

[0070] The MRI system 1 according to the embodiment described above includes a cooling unit that can switch between a normal power supply 3 and an uninterruptible power supply (UPS) as a power supply source and cools a superconducting coil 152 that generates a static magnetic field, an imaging system 11 for imaging a subject using the static magnetic field, an imaging system power supply switch SW that cuts off the power supply from the power supply source to the imaging system 11, and a switch control unit that controls the imaging system power supply switch SW based on the start information of the power supply from the uninterruptible power supply, and controls the switch to cut off the power supply to the imaging system 11 when a power failure in the normal power supply 3 continues for a first time t1. Thus, according to the present MRI system 1, the UPS 5 supplies power to the cooling unit and the imaging system 11 while the power failure in the normal power supply 3 continues for the first time t1, and can supply power only to the cooling unit after the power failure continues for the first time t1.

[0071] Moreover, according to the present MRI system 1, the first time t1 can be set based on the inductance L of the contact drive coil CC related to the imaging system power supply switch SW and the resistance R from the switch control unit to the contact drive coil CC. The first time t1 is set to, for example, ¼ cycle or more of the frequency of the voltage in the utility power supply 3 and within 1 minute.

[0072] For these reasons, the MRI system 1 can prevent the imaging system power supply switch SW from being opened due to a short-term voltage drop that allows the MRI apparatus 10 to maintain a normal state. A short-term voltage drop occurs, for example, due to a momentary interruption caused by lightning or the like (for example, a voltage drop of approximately 0.5 to 1 cycle or less of the frequency of the voltage in the commercial power supply). The normal state is maintained because, for example, the voltage drop is caused by the gradual drop in the voltage in the MRI apparatus 10 due to the equivalent resistance, inductance, and capacitance of the device that is the load of the MRI apparatus 10, power charging by a smoothing capacitor provided in the DC power supply of each unit of the MRI apparatus 10, and instantaneous switching of the power transmission line related to the power supply following a momentary power outage such as a momentary interruption.

[0073] From these points, according to the present MRI system 1, by preventing the imaging system power supply switch SW from being opened due to a momentary interruption, it is not necessary to restart each unit related to the imaging system 11 when power is supplied to the units, and it is possible to eliminate the waiting time of the subject due to the subject being evacuated from the MRI apparatus 10 during the restart. In other words, according to the present MRI system 1, in the case of a momentary interruption in which the MRI apparatus 10 side can sufficiently maintain a normal state, or a power outage of the normal power supply 3 lasts from 1 second to, for example, 30 seconds and is restored in an extremely short period of time, by setting the first time t1 to be greater than the time constant, it is possible to reduce unnecessary waiting time due to a system down of the imaging system 11 and reduce non-operating time (downtime) of the MRI apparatus 10.

[0074] 4 is a diagram showing an example of the relationship of the output power (also called apparent power) of the UPS 5 to the backup time during which the UPS 5 can operate, with respect to the UPS 5. For ease of explanation, the capacity of the power supplied by the UPS 5 is assumed to be 100 kVA. The power required by the MRI apparatus 10 during imaging of a subject, i.e., during normal operation, is assumed to be 100 kVA. The power required during execution of a power saving operation in the switching control process is assumed to be 25 kVA.

[0075] As shown in Fig. 4, the UPS 5 can operate with a backup time of about 90 minutes in power saving mode (required power: 25 kVA) during a power outage of the normal power supply 3. Also, as shown in Fig. 4, when 100 kVA of power is supplied to the MRI apparatus 10 by the UPS 5, the backup time of the MRI apparatus 10 by the UPS 5 is about 10 minutes (100 kVA (10 minute specification)). If it is permitted to shorten the backup time (90 minutes) during power saving mode, for example, during a power outage of the normal power supply 3, it becomes possible to supply power to all units in the MRI apparatus 10 for about 30 seconds with a power supply of 100 kVA by the UPS 5.

[0076] That is, when the first time t1 is set to 30 seconds, the MRI system 1 can perform imaging of the subject for 30 seconds from the start of the power outage of the utility power supply 3 without shutting down the imaging system 11 in the MRI apparatus 10. In this case, when the power outage time of the utility power supply 3 exceeds 30 seconds, the MRI system 1 can supply power from the UPS 5 only to the cooling unit related to cooling the superconducting coil 152 by power saving operation.

[0077] From the above, according to the present MRI system 1, even if the MRI apparatus 10 is normally able to continue to be used due to a short-term voltage drop of less than one cycle of the commercial power supply, the imaging system power supply switch SW is prevented from going into a power saving mode in which it is opened, so that interruption of examination due to the short interruption can be avoided. Therefore, according to the present MRI system 1, the throughput (examination efficiency) of examination on a subject can be improved.

[0078] In addition, the MRI system 1 according to the embodiment controls the imaging system power supply switch SW so that power is supplied to the imaging system 11 when the power recovery in the normal power supply 3 continues for the second time t2 after the power supply to the imaging system 11 is cut off by the imaging system power supply switch SW. As a result, according to the MRI system 1 according to the embodiment, the normal power supply 3 supplies power to the cooling unit while the power recovery continues for the second time t2, and can supply power to the cooling unit and the imaging system 11 after the power recovery continues for the second time t2. In addition, according to the present MRI system 1, the second time t2 can also be set in an analog manner based on the inductance L of the contact drive coil CC related to the imaging system power supply switch SW and the resistance R from the switch control unit to the contact drive coil CC. For example, the second time t2 is shorter than the first time t1.

[0079] For these reasons, the MRI system 1 according to the embodiment can reduce the number of cycles of power outages and power restorations, including momentary interruptions, in the normal power supply 3, compared to the conventional case. This can reduce the variation in the discharge and charge cycles in the UPS 5, i.e., the number of charge and discharge operations, and therefore can extend the life of the secondary battery in the UPS 5, i.e., the life of the UPS 5. For these reasons, the MRI system 1 according to the embodiment can improve the examination efficiency and reduce the total cost of the MRI system 1.

[0080] When the technical idea of ​​the embodiment is realized by a power supply control method, the power supply control method cools the superconducting coil 152 that generates a static magnetic field by the normal power supply 3 or the UPS 5, and when a power outage in the normal power supply 3 continues for a first time t1, controls an imaging system power supply switch SW that cuts off the power supply to an imaging system 11 related to imaging of a subject using a static magnetic field so as to cut off the power supply from the normal power supply 3 or the UPS 5 to the imaging system 11. The procedure and effects of the switching control process executed by the power supply control method are similar to those of the embodiment, and therefore will not be described.

[0081] According to the above-described embodiment, in the magnetic resonance imaging system 1, the throughput of the examination can be improved.

[0082] Although some embodiments have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, substitutions, modifications, and combinations of embodiments can be made without departing from the spirit of the invention. These embodiments and their modifications are included in the scope of the invention and its equivalents as described in the claims, as well as in the scope and spirit of the invention.

[0083] Regarding the above embodiment, the following supplementary notes are disclosed as one aspect and optional features of the invention. (Appendix 1) A magnetic resonance imaging system capable of switching between a normal power source and an uninterruptible power source as a power source, a cooling unit for cooling a superconducting coil that generates a static magnetic field; an imaging system for imaging a subject using the static magnetic field; a switch for cutting off the power supply from the power supply source to the imaging system; a switch control unit that controls the switch based on power supply start information from the uninterruptible power supply; Equipped with the switch control unit controls the switch to cut off the power supply to the imaging system when a power failure in the utility power source continues for a first time period. Magnetic resonance imaging system. (Appendix 2) The switch control unit may further control the switch so that power is supplied to the imaging system if power restoration to the normal power source continues for a second period of time after the switch cuts off the power supply to the imaging system. (Appendix 3) The normal power supply may supply power to the cooling unit while the power restoration continues for the second time period, and may supply power to the cooling unit and the imaging system after the power restoration has continued for the second time period. (Appendix 4) The first time and the second time may be set based on an inductance of a contact drive coil related to the switch and a resistance from the switch control unit to the contact drive coil. (Appendix 5) The first time period and the second time period may be set to desired values ​​by digital control. (Appendix 6) The first time period may be greater than the second time period. (Appendix 7) The uninterruptible power supply may supply power to the cooling unit and the imaging system while the power outage continues for the first time period, and may supply power to the cooling unit after the power outage has continued for the first time period. (Appendix 8) The first time period may be greater than or equal to ¼ cycle of the frequency of the voltage in the utility power supply and less than or equal to 1 minute. (Appendix 9) A normal power supply or an uninterruptible power supply is used to cool the superconducting coil that generates the static magnetic field. When a power failure in the normal power supply continues for a first time period, a switch for cutting off a power supply to an imaging system related to imaging of a subject using the static magnetic field is controlled so as to cut off the power supply from the normal power supply or the uninterruptible power supply to the imaging system. The power supply control method includes: [Explanation of symbols]

[0084] 1 MRI system 3 Regular power supply 5 Uninterruptible power supply (UPS) 7 Switch control circuit 10 MRI machine 11 Imaging system 13 System transformer 15 Static magnetic field generating unit 17 Relay 51 Power monitoring device 111 Gradient magnetic field power supply 113 RF Amplifier 115 Reconstruction Unit 151 Cooling Container 152 Superconducting Coil 153 Refrigeration Machine 155 Compressor 157 Cold Head 159 Refrigerator monitoring device CC Contact drive coil SW Imaging system power supply switch

Claims

1. A magnetic resonance imaging system capable of switching between a normal power source and an uninterruptible power source as a power source, a cooling unit for cooling a superconducting coil that generates a static magnetic field; an imaging system for imaging a subject using the static magnetic field; a switch for cutting off the power supply from the power supply source to the imaging system; a switch control unit that controls the switch based on power supply start information from the uninterruptible power supply; Equipped with the switch control unit controls the switch to cut off the power supply to the imaging system when a power outage in the normal power source continues for a first time period, and further controls the switch to supply power to the imaging system when a power recovery in the normal power source continues for a second time period after the switch has cut off the power supply to the imaging system. Magnetic resonance imaging system.

2. The normal power source is supplying power to the cooling unit while the power recovery continues for the second time period; supplying power to the cooling unit and the imaging system after the power recovery continues for the second time period; 10. The magnetic resonance imaging system of claim 1.

3. the first time and the second time are set based on an inductance of a contact driving coil related to the switch and a resistance from the switch control unit to the contact driving coil; 3. A magnetic resonance imaging system according to claim 1 or 2.

4. The first time and the second time can be set to desired values ​​by digital control.

3. A magnetic resonance imaging system according to claim 1 or 2.

5. The first time period is greater than the second time period. A magnetic resonance imaging system according to any one of the preceding claims.

6. The uninterruptible power supply comprises: supplying power to the cooling unit and the imaging system while the power outage continues for the first period of time; supplying power to the cooling unit after the power outage has continued for the first period of time; A magnetic resonance imaging system according to any one of the preceding claims.

7. The first time period is greater than or equal to ¼ cycle of the frequency of the voltage of the utility power supply and less than or equal to 1 minute. A magnetic resonance imaging system according to any one of the preceding claims.

8. A normal power supply or an uninterruptible power supply is used to cool the superconducting coil that generates the static magnetic field. when a power failure in the normal power supply continues for a first period of time, a switch for cutting off the power supply to an imaging system related to imaging of a subject using the static magnetic field is controlled to cut off the power supply from the normal power supply or the uninterruptible power supply to the imaging system, and when power restoration in the normal power supply continues for a second period of time after the power supply to the imaging system is cut off by the switch, the switch is further controlled to supply power to the imaging system. The power supply control method includes:

9. A magnetic resonance imaging system capable of switching between a normal power source and an uninterruptible power source as a power source, a cooling unit for cooling a superconducting coil that generates a static magnetic field; an imaging system for imaging a subject using the static magnetic field; a switch for cutting off the power supply from the power supply source to the imaging system; a switch control unit that controls the switch based on power supply start information from the uninterruptible power supply; Equipped with the switch control unit controls the switch to cut off the power supply to the imaging system when a power outage in the utility power source continues for a first time period defined as a time period corresponding to a momentary interruption or a duration of the power outage that exceeds the first time period; the uninterruptible power supply supplies power to the cooling unit and the imaging system while the power outage continues for the first time period, and supplies power to the cooling unit after the power outage has continued for the first time period. Magnetic resonance imaging system.

10. The first time is set based on an inductance of a contact driving coil related to the switch and a resistance from the switch control unit to the contact driving coil.

10. A magnetic resonance imaging system according to claim 9.

11. The first time period is greater than or equal to 1 / 4 cycle of the frequency of the voltage in the normal power supply and less than or equal to 1 minute.

11. A magnetic resonance imaging system according to claim 9 or 10.

12. A normal power supply or an uninterruptible power supply is used to cool the superconducting coil that generates the static magnetic field. When a power failure in the normal power supply continues for a first time period defined as a time period corresponding to a momentary interruption or a duration of the power failure exceeding the time period, a switch for cutting off the power supply to an imaging system related to imaging of the subject using the static magnetic field is controlled so as to cut off the power supply from the normal power supply or the uninterruptible power supply to the imaging system. A power supply control method comprising: supplying power from the uninterruptible power supply to a cooling unit that cools the superconducting coil and to the imaging system while the power outage continues for the first time period; After the power outage continues for the first period of time, power is supplied to the cooling unit from the uninterruptible power supply. Power supply control method.

13. The first time is set based on an inductance of a contact driving coil related to the switch and a resistance from a switch control circuit that controls the switch to the contact driving coil. The power supply control method according to claim 12.

14. The first time period is greater than or equal to 1 / 4 cycle of the frequency of the voltage in the normal power supply and less than or equal to 1 minute. The power supply control method according to claim 12 or 13.

15. A magnetic resonance imaging system capable of switching between a normal power source and an uninterruptible power source as a power source, a cooling unit for cooling a superconducting coil that generates a static magnetic field; an imaging system for imaging a subject; a switch for cutting off the power supply from the power supply source to the imaging system; a switch control unit that controls the switch based on power supply start information from the uninterruptible power supply; Equipped with the switch control unit controls the switch to cut off the power supply to the imaging system when a power outage in the normal power supply continues for a first time period defined as a time period corresponding to a momentary interruption or a duration of the power outage that exceeds the first time period. Magnetic resonance imaging system.

16. 16. The magnetic resonance imaging system according to claim 15, wherein the imaging system comprises a gradient magnetic field power supply for generating a gradient magnetic field for position identification, a gradient magnetic field coil, a transmission circuit equipped with an RF amplifier for supplying energy for causing a magnetic resonance phenomenon, a transmission coil, a receiving coil, a receiving circuit, a sequence control circuit, a bed, and a computer system equipped with a reconstruction unit for imaging a signal obtained as a result of the magnetic resonance phenomenon.

17. The first time period is set based on an inductance of a contact driving coil related to the switch and a resistance from the switch control unit to the contact driving coil.

17. A magnetic resonance imaging system according to claim 15 or 16.

18. The first time period is greater than or equal to 1 / 4 cycle of the frequency of the voltage in the normal power supply and less than or equal to 1 minute. A magnetic resonance imaging system according to any one of claims 15 to 17.

Images