JP7616865B2 - Magnetic resonance imaging equipment - Google Patents

Description

The embodiments disclosed in this specification and in the drawings relate to a magnetic resonance imaging apparatus .

Conventionally, a magnetic resonance imaging device (hereinafter referred to as an MRI (Magnetic Resonance Imaging) device) having a superconducting static magnetic field magnet (superconducting coil) uses, for example, about 1000 liters of helium (He) as a refrigerant. In recent years, the price of helium has risen sharply, which can put a strain on the lifetime cost of an MRI device from purchase to disposal. In order to suppress the lifetime cost, it is effective to reduce the refrigerant capacity as much as possible. However, when the refrigerant capacity is reduced, there is a disadvantage that the time until a quench occurs due to a rise in temperature inside the superconducting magnet during a power outage caused by an unexpected accident such as a natural disaster or lightning strike is shortened. When a quench occurs, it becomes necessary to continue cooling the helium for about one month, or to replace it with cooled helium, in order to transition the conductive state of the superconducting coil from a normal conductive state to a superconducting state.

In order to prepare for power outages other than momentary blackouts, for example, hospital facilities can be provided with their own power source (emergency power source) that is separate from commercial power sources, and quenching can be prevented by switching the power supply from commercial power to the emergency power source during a power outage. However, if the entire MRI system is operated while using the emergency power source, the power capacity required for the emergency power source increases, the costs of the emergency power source increase, and the time that the emergency power source can supply power can be shortened.

International Publication No. 2013-172148

One of the problems that the embodiments disclosed in this specification and the drawings attempt to solve is to reduce the costs associated with magnetic resonance imaging apparatus. However, the problems that the embodiments disclosed in this specification and the drawings attempt to solve are not limited to the above problem. Problems that correspond to the effects of each configuration shown in the embodiments described below can also be positioned as other problems.

The magnetic resonance imaging apparatus according to the embodiment is capable of switching the power supply source from a normal power source to an emergency power source, and includes a cooling unit and a power supply selection unit. The cooling unit cools a superconducting coil that generates a static magnetic field. When the emergency power source is the power supply source, the power supply selection unit maintains a power supply relationship in which the cooling unit is selected as the power supply destination based on monitoring information related to monitoring of the state of power supply by the normal power source.

FIG. 1 is a block diagram showing an example of an MRI apparatus when power is supplied from a normal power source according to an embodiment. FIG. 2 is a block diagram showing an example of an MRI apparatus when power is supplied from an emergency power supply according to the embodiment. FIG. 3 is a timing chart showing an example of operation timing in the supply switching process according to the embodiment. FIG. 4 is a flowchart illustrating an example of a procedure of a supply switching process according to the embodiment. FIG. 5 is a block diagram showing an example of an MRI apparatus when power is supplied from an emergency power supply according to a first modified example of the embodiment. FIG. 6 is a block diagram showing an example of an MRI apparatus when power is supplied from an emergency power supply according to a second modified example of the embodiment.

Hereinafter, an embodiment of a magnetic resonance imaging apparatus and a power supply control method will be described in detail with reference to the drawings. FIG. 1 is a block diagram showing an example of a magnetic resonance imaging apparatus (hereinafter referred to as an MRI (Magnetic Resonance Imaging) apparatus) 1 when power is supplied from a normal power source 3. The normal power source 3 corresponds to the facility power source in the hospital or the like in which the MRI apparatus 1 is installed, i.e., a commercial power source. Note that the technical idea of this embodiment may be realized as an MRI system including an MRI apparatus 1, an emergency power source 5, and a power system changeover switch 7.

The MRI apparatus 1 is connected to a normal power source 3 or an emergency power source 5, and can switch between the normal power source 3 and the emergency power source 5 as the power supply source. Specifically, the MRI apparatus 1 is electrically connected to the normal power source 3 or at least one emergency power source 5 via a power system changeover switch 7.

The normal power supply 3 supplies power to the MRI apparatus 1 via the power supply system changeover switch 7. At this time, the power supplied from the normal power supply 3 is supplied to all units of the MRI apparatus 1, such as the imaging system 11 and the static magnetic field generating unit 15, via the system transformer 13 in the MRI apparatus 1. Note that the power supplied from the normal power supply 3 may also be supplied to a console or bed (not shown).

The emergency power supply 5 has a power supply monitoring device (or function) 51. The emergency power supply 5 is a power supply independent of the normal power supply 3, and generates, for example, three-phase AC. The emergency power supply 5 that generates three-phase AC has, for example, a generator with a motor, and generates three-phase AC by driving the motor. The power supply monitoring device 51 functions as a monitor that monitors the state of power supply to the MRI apparatus 1 by the normal power supply 3. The emergency power supply 5 outputs monitoring information related to the monitoring of the state of power supply by the normal power supply 3 to the MRI apparatus 1. The monitoring information includes, for example, information on the power supply state of the normal power supply 3 (hereinafter referred to as power outage information) and information on the electrical connection with the normal power supply 3 or emergency power supply 5, which is the power supply source of the MRI apparatus 1 (hereinafter referred to as connection destination information). The monitoring information is output from the power supply monitoring device 51, for example, as a current signal.

The power outage information is information indicating the presence or absence of a power outage in the normal power source 3, i.e., the commercial power source, and is used to switch the imaging system power supply switch 17 between the ON state (closed) and the OFF state (open). Specifically, the power supply monitoring device 51 outputs the power outage information to the imaging system power supply switch 17 in the MRI device 1. The power outage information may be output to the imaging system power supply switch 17 via an insulating transformer. In this case, the insulating transformer is provided on the path between the imaging system power supply switch 17 and the power supply monitoring device 51. The connection destination information is information for changing the connection destination of the current in the power supply system changeover switch 7, and is used to change the connection destination of the current in the power supply system changeover switch 7. The power supply monitoring device 51 outputs the connection destination information to the power supply system changeover switch 7.

Figure 2 is a block diagram showing an example of the MRI device 1 when power is being supplied from the emergency power supply 5. The difference from Figure 1 is that the power supply system changeover switch 7 is connected to the emergency power supply 5 side, and the imaging system power supply switch 17 is open.

The power supply system changeover switch 7 switches the connection of the current to the MRI device 1 between the normal power supply 3 and the emergency power supply 5 based on the connection information output from the power supply monitoring device 51. For example, if a power outage occurs in the normal power supply 3, the power supply system changeover switch 7 switches the connection of the current to the MRI device 1 from the normal power supply 3 to the emergency power supply 5. Also, when the normal power supply 3 is restored, the power supply system changeover switch 7 switches the connection of the current to the MRI device 1 from the emergency power supply 5 to the normal power supply 3. As a result, when the normal power supply 3 recovers from the power outage, power is supplied from the normal power supply 3 to the cooling unit described below.

The MRI apparatus 1 has an imaging system (imaging device) 11, a system transformer 13, a static magnetic field generating unit 15, and an imaging system power supply switch 17. The static magnetic field generating unit 15 has a cooling vessel 151 having a superconducting coil 152 for generating a static magnetic field, a refrigerator 153, and a refrigerator monitoring device 159. The cooling vessel 151, the refrigerator 153, and the refrigerator monitoring device 159 constitute a cooling section (cooling device) that cools the superconducting coil 152 that generates the static magnetic field. That is, the cooling section has a refrigerator 153 that cools a refrigerant for cooling the superconducting coil 152. The refrigerant is, for example, helium.

The imaging system 11 has various units related to imaging of the subject. 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 to cause 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 the signal obtained as a result of the magnetic resonance phenomenon. Each component of the imaging system 11 will be described later.

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 emergency power supply 5 to the static magnetic field generating unit 15 and the imaging system power supply switch 17. The system transformer 13 uses its power distribution function to supply the power supplied from the normal power supply 3 or the emergency power supply 5 to the static magnetic field generating unit 15 and the imaging system power supply switch 17.

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. Inside the cooling vessel 151, liquid helium and helium gas obtained by vaporizing the liquid helium are in equilibrium.

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 inside 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 inside the cooling container 151 decreases. If the pressure inside the cooling container 151 decreases and becomes negative pressure, air will flow into the cooling container 151. The heater is controlled by the refrigerator monitor 159 to keep the pressure inside the cooling container 151 within a preset range, and warms the helium inside the cooling container 151.

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, an exhaust pipe, a vent valve, an intake valve, a buffer tank, etc. (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 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 chiller can be existing devices, so a description of the air-cooling device and chiller will be omitted.

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

The cold head 157 expands the high-pressure refrigerant gas supplied through the supply pipe, and cools the refrigerant in the cooling vessel 151. As a result, the cold head 157 cools the refrigerant to a temperature below the boiling point of the refrigerant. When the cooling vessel 151 is cooled to a certain level or more, the helium gas in the cooling vessel 151 is recondensed into liquid helium. Note that while Figures 1 and 2 show an example in which one cold head 157 is installed in the cooling vessel 151, the number of cold heads 157 is not limited to one, and multiple cold heads 157 may be used.

The vent valve and intake valve are provided on the 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 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.

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

The imaging system power supply switch 17 is provided between the system transformer 13 and multiple units related to power supply in the imaging system 11. That is, the imaging system power supply switch 17 is provided before the power supply line to multiple units such as the gradient magnetic field power supply 111 that are not involved in cooling the static magnetic field generating unit 15. The imaging system power supply switch 17 has multiple switches related to the power supply to the multiple units in the imaging system 11. As shown in Figures 1 and 2, the imaging system power supply switch 17 has, for example, a first switch SW1 that can be electrically connected to the gradient magnetic field power supply 111, a second switch SW2 that can be electrically connected to the RF amplifier 113, and a third switch SW3 that can be electrically connected to the reconstruction unit 115.

1 and 2, the multiple units in the imaging system 11 are described as the gradient magnetic field power supply 111, the RF amplifier 113, and the reconstruction unit 115, but are not limited thereto, and may further include other units related to the imaging system 11, such as a bed. In this case, the imaging system power supply switch 17 has an additional switch that can be electrically connected to other units. As shown in FIG. 1, when power is supplied from the normal power supply 3, all switches in the imaging system power supply switch 17 are closed. Therefore, power is supplied from the normal power supply 3 to all units in the MRI device 1. On the other hand, when the power supply from the normal power supply 3 is stopped, that is, when a power outage occurs, as shown in FIG. 2, the power supply source is selected as the emergency power supply 5 by the power supply system changeover switch 7, and the imaging system power supply switch 17 is opened based on the monitoring information sent from the emergency power supply 5. As a result, when the normal power supply 3 is out of power, the power supplied from the emergency power supply 5 is supplied only to the units required for cooling the superconducting coil 152.

When the emergency power supply 5 is the power supply source, the imaging system power supply switch 17 maintains a power supply relationship in which the cooling unit is selected as the power supply destination based on monitoring information. Specifically, the imaging system power supply switch 17 switches between closed (ON) and open (OFF) states of multiple switches based on power outage information output from the power supply monitoring device 51. For example, when a power outage occurs in the normal power supply 3, the imaging system power supply switch 17 opens the multiple switches. Also, when power is restored to the normal power supply 3, the imaging system power supply switch 17 closes the multiple switches. The imaging system power supply switch 17 corresponds to a power supply selection unit. The power supply selection unit may be composed of the multiple switches described above and a processor that controls the opening and closing of the switches. At this time, the processor controls the opening and closing of the multiple switches based on the power outage information.

When the power consumption of the MRI device 1 is reduced, the power supply selection unit maintains the power supply relationship in which the cooling unit is selected as the power supply destination even if a power-on instruction to the MRI device 1, i.e., an instruction to turn on the power to the MRI device 1, is input by the user via the input interface described below.

The components contained in the imaging system 11 are briefly described below.

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.

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 device 1 using power supplied via the system transformer 13 and the imaging system power supply switch 17.

The transmitting coil receives RF (Radio Frequency) pulses from the transmitting circuit and generates a high-frequency magnetic field in the imaging space of the MRI device 1.

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 17, and supplies it to the transmission coil.

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 a configuration in which the receiving coil also serves as the transmitting coil may be adopted.

The receiving circuit performs analog-to-digital (AD) conversion on the analog MR signal output from the receiving coil to generate MR data. The receiving circuit transmits the generated MR data to a sequence control circuit.

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 defines the 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, it transfers the received MR data to the computer system. The sequence control circuit is realized, for example, by a processor.

The bed has a top plate on which the 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 moving parts. The bed and the top plate are moved in the longitudinal direction and the vertical direction of the top plate under the control of a computer system.

The computer system performs overall control of the MRI apparatus 1 and generates MR images. The computer system includes, for example, a network interface, a memory circuit, a processing circuit, an input interface, and a display.

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

The input interface accepts various instructions (e.g., a power-on instruction) and information input from an operator. The input interface can be realized by, for example, a trackball, a switch button, a mouse, a keyboard, a touchpad that performs input operations by touching the operation surface, a touch screen that integrates a display screen and a touchpad, a non-contact input circuit that uses an optical sensor, and a voice input circuit. The input interface is connected to a processing circuit, and converts input operations received from an operator into electrical signals and outputs them to the processing circuit. Note that in this specification, the input interface is not limited to those that have physical operating parts such as a mouse and a keyboard. For example, an electrical signal processing circuit that receives electrical signals corresponding to input operations from an external input device provided separately from the computer system and outputs these electrical signals to a control circuit is also included as an example of an input interface.

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

The processing circuitry controls the entire MRI apparatus 1. More specifically, the processing circuitry has, 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 that can be executed by a computer. The processing circuitry is a processor. For example, the processing circuitry realizes the function corresponding to each program by reading and executing the program from the storage circuitry. In other words, the processing circuit in a state in which each program has been read has each function, such as the imaging control function and the reconstruction function.

In the above description, an example was 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 circuits 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)).

When the processor is, for example, a CPU, the processor realizes a function by reading and executing a program stored in a memory circuit. On the other hand, when the processor is an ASIC, instead of storing a program in a memory 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 its function. Also, while a single memory circuit has been described as storing a program corresponding to each processing function, multiple memory circuits may be distributed and arranged, and the processing circuit may read the corresponding program from each individual memory circuit.

The imaging control function controls each part of the MRI device 1 to capture magnetic resonance images. More specifically, the imaging control function generates sequence information, collects MR data, etc.

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 17. 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, for example, in a memory circuit.

The control process (hereinafter referred to as supply switching process) for switching the power supply destination in the MRI apparatus 1 in association with switching the power supply source executed by the MRI apparatus 1 of this embodiment configured as described above will be described with reference to Figs. 3 and 4. Fig. 3 is a timing chart showing an example of the operation timing in the supply switching process according to the embodiment. Fig. 4 is a flowchart showing an example of the procedure of the supply switching process according to the embodiment.

(Supply switching process)
(Step S401)
If the power supply monitoring device 51 in the emergency power supply 5 does not detect a power outage in the normal power supply 3 (NO in step S401), this step is repeated. If the power supply monitoring device 51 detects a power outage in the normal power supply 3 (YES in step S401), the process of step S402 is executed. The detection of a power outage in FIG. 3 corresponds to time t1. Upon detection of a power outage, the power supply monitoring device 51 outputs power outage presence/absence information to the imaging system power supply switch 17. At this time, the power outage presence/absence information is a signal notifying of a power outage and is used to open the imaging system power supply switch 17. Furthermore, upon detection of a power outage, the power supply monitoring device 51 outputs connection destination information to the power system changeover switch 7. At this time, the connection destination information corresponds to a signal for switching the connection destination of the power supply source from the normal power supply 3 to the emergency power supply 5.

(Step S402)
The emergency power supply 5 is started. Specifically, at time t1 in Fig. 3, the engine in the emergency power supply 5 is started, and the emergency power supply 5 starts generating power.

(Step S403)
The power supply system changeover switch 7 switches the connection from the normal power supply 3 to the emergency power supply 5. Specifically, the power supply system changeover switch 7 switches the power supply source to the MRI apparatus 1 from the normal power supply 3 to the emergency power supply 5 in accordance with the connection destination information upon receipt of the connection destination information, i.e., at time t2 shown in Fig. 3. In other words, the power supply source switches from the normal power supply 3 to the emergency power supply 5 when the normal power supply 3 fails.

(Step S404)
The imaging system power supply switch 17 is opened. Specifically, the imaging system power supply switch 17 opens the first switch SW1 to the third switch SW3 in accordance with the power outage presence/absence information upon receipt of the power outage presence/absence information, i.e., at time t2 shown in FIG. 3 .

(Step S405)
For example, the power supply monitoring device 51 determines whether or not the switching time has elapsed since the detection of the power outage. The switching time corresponds to the period from the start of the emergency power supply 5 until the power (e.g., voltage) output from the emergency power supply 5 becomes stable. That is, the switching time is a period TL from the start time (t1 in FIG. 3) of the emergency power supply 5 until the power generated by the emergency power supply 5 becomes stable, and is, for example, within 40 seconds. Note that the switching time TL may be appropriately set to, for example, a time width of one cycle or more of the frequency of the normal power supply 3 and within 10 minutes. In addition, when a large-capacity storage battery is used as the emergency power supply 5, this step is not necessary.

If the switching time TL has not elapsed since the detection of a power outage, i.e., the start time t1 of the engine in the emergency power source 5 (NO in step S405), the processing in this step is repeated. If the switching time TL has elapsed since the detection of a power outage, i.e., the start time t1 of the engine in the emergency power source 5 (YES in step S405), the processing in step S406 is executed.

(Step S406)
The supply of power from the emergency power supply 5 to the static magnetic field generating unit 15 is started. That is, power is selectively supplied from the emergency power supply 5 to the cooling unit. In other words, a power supply relationship is maintained in which the cooling unit is selected as the power supply destination. The time when the supply of power from the emergency power supply 5 to the static magnetic field generating unit 15 starts corresponds to time t3 shown in FIG. 3. That is, at time t3, power is supplied from the emergency power supply 5 to the static magnetic field generating unit 15.

(Step S407)
If the power supply monitoring device 51 in the emergency power supply 5 does not detect the restoration of power in the normal power supply 3 (NO in step S407), this step is repeated. Even if a power-on instruction is input by the user via the input interface during the period from YES in step S401 to NO in this step, the power generated by the emergency power supply 5 is not supplied to the imaging system 11 but is supplied to the cooling unit.

When the power supply monitoring device 51 detects the restoration of power to the normal power supply 3 (YES in step S407), the process of step S408 is executed. The detection of power restoration in FIG. 3 corresponds to time t4. Upon detecting the restoration of power, the power supply monitoring device 51 outputs power outage information to the imaging system power supply switch 17. At this time, the power outage information is a signal notifying the restoration of power, and is used to close the imaging system power supply switch 17. Furthermore, upon detecting the restoration of power, the power supply monitoring device 51 outputs connection destination information to the power system changeover switch 7. At this time, the connection destination information corresponds to a signal that switches the connection destination of the power supply source from the emergency power supply 5 to the normal power supply 3.

(Step S408)
The imaging system power supply switch 17 is closed. Specifically, the imaging system power supply switch 17 closes the first switch SW1 to the third switch SW3 in accordance with the power outage presence/absence information upon receipt of the power outage presence/absence information, i.e., at time t5 shown in FIG. 3 .

(Step S409)
The power supply system changeover switch 7 switches the connection from the emergency power supply 5 to the normal power supply 3. Specifically, the power supply system changeover switch 7 switches the power supply source to the MRI apparatus 1 from the emergency power supply 5 to the normal power supply 3 in accordance with the connection destination information upon receipt of the connection destination information, i.e., at time t6 shown in Fig. 3. As a result, when the normal power supply 3 recovers from a power outage, power is supplied from the normal power supply 3 to the cooling unit.

(Step S410)
Power generation is stopped in the emergency power supply 5. Specifically, the operation of the engine in the emergency power supply 5 is stopped. With the above, the supply switching process is completed.

The MRI apparatus 1 according to the embodiment described above can switch between the normal power supply 3 and the emergency power supply 5 as the power supply source, cools the superconducting coil 152 that generates a static magnetic field, and maintains a power supply relationship in which the cooling unit is selected as the power supply destination based on monitoring information regarding the monitoring of the power supply state by the normal power supply 3 when the emergency power supply 5 is the power supply source. In addition, the cooling unit in the MRI apparatus 1 according to the embodiment further includes a water cooling device that water-cools the refrigerant or an air cooling device that air-cools the refrigerant.

As a result, the MRI apparatus 1 according to this embodiment can supply power preferentially to the cooling section that cools the superconducting coil 152 even when the normal power supply 3 is interrupted, so that the amount of expensive refrigerant such as helium used can be reduced as much as possible. This allows the cost associated with refrigerants to be reduced. In addition, according to this MRI apparatus 1, when the normal power supply 3 is interrupted, power can be supplied only to the cooling section based on the monitoring information (power interruption information and connection destination information) output from the power supply monitoring device 51 in the emergency power supply 5, so that the power capacity of the emergency power supply 5 can be reduced.

In particular, when the emergency power supply 5 is a power supply independent of the normal power supply 3 and is a generator capable of generating three-phase AC by a motor, the MRI apparatus 1 according to this embodiment can reduce the power supply capacity of the emergency power supply 5, thereby reducing the purchase cost of the emergency power supply 5, which increases according to the power supply capacity of the emergency power supply 5. For these reasons, the MRI apparatus 1 according to this embodiment can reduce the total cost related to the MRI apparatus 1 (the cost required from purchase to disposal, also known as the lifetime cost). In other words, the MRI apparatus 1 according to this embodiment can reduce the total cost of the MRI apparatus 1 by reducing the generating capacity of the emergency power supply 5.

For example, typically, the refrigerator 153 consumes approximately 25 kVA of power, and the imaging system 11 consumes 75 kVA. According to this embodiment, as an additional effect, it is possible to extend the operating time of the generator in the emergency power supply 5 by, for example, nearly four times. In addition, due to the price difference between the emergency power supplies 5 of 100 kVA and 25 kVA, it is possible to reduce the lifetime cost of the MRI apparatus 1, and the installation space for the emergency power supply 5 can be reduced according to the difference in power consumption.

In addition, according to the MRI apparatus 1 of this embodiment, after the start of the emergency power supply 5, the period (switching time TL) until the power output from the emergency power supply 5 stabilizes is reached, and then power is selectively supplied from the emergency power supply 5 to the cooling unit. This makes it possible to prevent unnecessary switching operations for switching the power supply source to the emergency power supply 5 from occurring in advance, for example, when a momentary interruption (e.g., a momentary power outage of about 1/4 cycle) occurs in the normal power supply 3 that does not affect the operation of the MRI apparatus 1, and thus reduces the cost associated with the use of the emergency power supply 5, i.e., reduces the lifetime cost of the MRI apparatus 1. Note that the momentary interruption is not limited to 1/4 cycle, and may be, for example, within 1/2 cycle to 1 second.

In addition, according to the MRI apparatus 1 of this embodiment, the power outage information can be output from the emergency power supply 5 to the power supply selection unit via the insulating transformer. As a result, according to the MRI apparatus 1 of this embodiment, the emergency power supply 5 itself can be excluded from the configuration that is the target of leakage current measurement, and it is no longer necessary to include the emergency power supply 5 in the configuration of the medical device, so that the cost related to leakage current measurement can be reduced. Furthermore, according to the MRI apparatus 1 of this embodiment, even if a user inputs a power-on command to the MRI apparatus 1 when the power consumption of the MRI apparatus 1 is reduced, the power supply relationship in which the cooling unit is selected as the power supply destination can be continuously maintained. As a result, according to the MRI apparatus 1 of this embodiment, power can be supplied preferentially to the cooling unit, so that the release of refrigerant due to quenching or the like can be prevented, and the cost related to the refrigerant can be reduced.

Furthermore, according to the MRI apparatus 1 of this embodiment, when the normal power supply 3 recovers from a power outage, power is supplied from the normal power supply 3 to the cooling unit. As a result, when the normal power supply 3 is restored, the power supply source for the MRI apparatus 1 is switched to the normal power supply 3, so the power capacity of the emergency power supply 5 can be reduced. Furthermore, according to the MRI apparatus 1 of this embodiment, an inverter-driven motor is used as the motor used in the refrigerator 153. This makes it possible to reduce the inrush current generated when the motor in the refrigerator 153 is driven during a power outage of the normal power supply 3, and therefore the power capacity of the emergency power supply 5 can be further reduced. As a result, the purchase cost of the emergency power supply 5 can be reduced.

(First Modification)
The first modification is characterized in that the MRI apparatus 1 shown in Fig. 1 and Fig. 2 further includes an uninterruptible power supply (hereinafter, referred to as UPS). Fig. 5 is a block diagram showing an example of the MRI apparatus 2 according to the first modification when power is supplied from the emergency power supply 5. In the first modification, since the UPS 12 is included, the power supply to the refrigerator 153 is not interrupted even in the event of a power outage, and as a result, no inrush current occurs due to starting the motor of the refrigerator 153. Therefore, the motor provided in the refrigerator 153 is not limited to being inverter-driven, and any motor drive method can be easily applied.

UPS 12 is provided between the system transformer 13 and the static magnetic field generating unit 15. UPS 12 supplies power to the cooling unit during the period when the power supply source is switched from the normal power supply 3 to the emergency power supply 5. Specifically, UPS 12 supplies power to the static magnetic field generating unit 15 during the period from after YES in step S401 in FIG. 4 until YES in step S405, in other words, during the period from time t1 to time t3 in FIG. 3. The timing chart and the procedure for the supply switching process are similar to those in FIG. 3 and FIG. 4, respectively, and therefore will not be described.

According to the MRI apparatus 2 according to the first modification of this embodiment, during the period when the power supply source is switched from the normal power supply 3 to the emergency power supply 5, the UPS 12 that supplies power to the cooling unit is provided between the system transformer 13 and the static magnetic field generating unit 15. As a result, according to this MRI apparatus 2, it is possible to suppress the generation of an inrush current that occurs when the emergency power supply 5 starts supplying power to the refrigerator 153 during a power outage. Therefore, according to this MRI apparatus 2, it is not necessary to select an emergency power supply having a power supply capacity that can tolerate the inrush current consumed by the motor, and in some cases, it is sufficient to prepare an emergency power supply 5 having a power supply capacity of less than half the power supply capacity taking the inrush current into account, so that the cost of purchasing the emergency power supply 5 can be significantly reduced. In other words, according to the MRI apparatus 2 according to the first modification of this embodiment, the UPS 12 is provided to suppress the generation of an inrush current caused by the start of the motor in the refrigerator 153, which can contribute to reducing the power supply capacity of the emergency power supply 5 to be prepared, and the lifetime cost of the MRI apparatus 2 can be reduced.

(Second Modification)
In the second modified example, the output destination of the normal power supply 3 is directly connected to the system transformer 13 , and the power from the emergency power supply 5 is supplied to the static magnetic field generating unit 15 without passing through the system transformer 13 .

Figure 6 is a diagram showing an example of the MRI apparatus 4 when power is supplied from the emergency power supply 5 according to the second modified example. As shown in Figure 6, the MRI apparatus 4 has a power supply system changeover switch 18. The power supply system changeover switch 18 in this modified example corresponds to a power supply selection unit. As shown in Figure 6, the power supply system changeover switch 18 electrically connects the emergency power supply 5 and the cooling unit in a power supply relationship in which the cooling unit is selected as the power supply destination, without passing through the system transformer 13 that distributes power to the imaging system 11 related to imaging of the subject. The power supply system changeover switch 18 in the second modified example switches between the output from the system transformer 13 and the output from the emergency power supply 5 based on the connection destination information. In addition, a UPS 12 is arranged between the power supply system changeover switch 18 and the static magnetic field generating unit 15.

The supply switching process in the second modified example will be described with reference to FIG. 4, focusing on the process that differs from that in FIG. 4. In the second modified example, the imaging system power supply switch 17 described in the embodiment and the first modified example is not required, and therefore step S404 is not required.

(Step S403)
The power supply system changeover switch 18 switches the connection from the output of the system transformer 13 connected to the normal power supply 3 to the emergency power supply 5. Specifically, upon receipt of the connection destination information, i.e., at time t2 shown in Fig. 3, the power supply system changeover switch 18 switches the power supply source to the MRI apparatus 4 from the normal power supply 3 to the emergency power supply 5 in accordance with the connection destination information.

UPS 12 supplies power to the cooling section of static magnetic field generating unit 15 during the period when the power supply source is switched from normal power supply 3 to emergency power supply 5. Specifically, UPS 12 supplies power to static magnetic field generating unit 15 during the period from after YES in step S401 in FIG. 4 until YES in step S405, in other words, during the period from time t1 to time t3 in FIG. 3. The timing chart and the procedure for the supply switching process are similar to those in FIG. 3 and FIG. 4, respectively, and therefore will not be described.

According to the MRI apparatus 4 according to the second modification of this embodiment, the emergency power supply 5 and the cooling unit are electrically connected as a power supply relationship in which the cooling unit is selected as the power supply destination, without passing through the system transformer 13 that distributes power to the imaging system 11 related to imaging of the subject. As a result, according to this MRI apparatus 4, the inrush current caused by residual magnetization at the start of the system transformer 13 does not need to be supported by the power capacity of the emergency power supply 5, and the refrigerator 153 is backed up by the UPS 12. Therefore, according to this MRI apparatus 4, during the period from the start of the emergency power supply 5 to the turning off of the power supply (the period from time t1 to time t3, for example 40 seconds if the emergency power supply 5 is a motor type), the refrigerator 153 does not stop, and it is not necessary to cover the consumption of the inrush current in the refrigerator 153 with the power capacity of the emergency power supply 5.

For these reasons, with the MRI device 4 according to the second modification, the power supply system changeover switch 18 is disposed after the system transformer 13 as viewed from the power supply side, and the UPS 12 is disposed after the power supply system changeover switch 18, thereby suppressing the generation of inrush currents caused by starting the motor in the refrigerator 153 and the system transformer 13, and further reducing the power generation capacity of the emergency power supply 5. This allows the cost of the MRI device 4 to be further reduced.

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 using the normal power supply 3 or the emergency power supply 5, and when the emergency power supply 5 is the power supply source, the power supply relationship is maintained in which the cooling unit that cools the superconducting coil 152 is selected as the power supply destination based on monitoring information regarding the monitoring of the power supply state by the normal power supply 3. The procedure and effect of the supply switching process executed by the power supply control method are the same as those of the embodiment, so a description will be omitted.

According to the embodiments described above, the costs associated with the MRI device 1 can be reduced.

Although several 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 within the scope of the invention and its equivalents as set forth in the claims, as well as the scope and spirit of the invention.

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 apparatus capable of switching from a normal power source to an emergency power source as a power supply source,
a cooling unit for cooling a superconducting coil that generates a static magnetic field;
a power supply selection unit that maintains a power supply relationship in which the cooling unit is selected as a power supply destination based on monitoring information regarding monitoring of a state of power supply by the normal power source when the emergency power source is the power supply source;
A magnetic resonance imaging apparatus comprising:
(Appendix 2)
The power supply source may be switched from the normal power supply to the emergency power supply when a power failure occurs in the normal power supply.
(Appendix 3)
The cooling unit may include a refrigerator that cools a refrigerant for cooling the superconducting coil.
(Appendix 4)
The cooling unit may further include a water cooling device that water-cools the refrigerant or an air cooling device that air-cools the refrigerant.
(Appendix 5)
The emergency power supply may be a power supply independent of the normal power supply, and may generate three-phase AC.
(Appendix 6)
The monitoring information may include information on a power-on state of the normal power source, and information on an electrical connection to the normal power source or the emergency power source which is the power supply source.
(Appendix 7)
After the start of the emergency power supply, power may be selectively supplied from the emergency power supply to the cooling unit when a period until the power output from the emergency power supply becomes stable has elapsed. (Additional Note 8)
The information on the power supply state may be output from the emergency power supply to the power supply selection unit via an insulating transformer.

(Appendix 9)
The power supply selection unit may maintain the power supply relationship when a user inputs an instruction to power on the magnetic resonance imaging apparatus during reduction of power consumption of the magnetic resonance imaging apparatus.
(Appendix 10)
When the utility power source recovers from a power outage, power may be supplied from the utility power source to the cooling unit.
(Appendix 11)
The cooling unit may include a refrigerator that cools a refrigerant for cooling the superconducting coil,
The motor of the compressor in the refrigerator may be inverter driven.
(Appendix 12)
The power supply source may further include an uninterruptible power supply device that supplies power to the cooling unit during a period in which the power supply source is switched from the normal power supply to the emergency power supply.
(Appendix 13)
The power supply selection section may electrically connect the emergency power supply and the cooling section as the power supply relationship without passing through a system transformer that distributes power to an imaging system related to imaging of a subject.
(Appendix 14)
The superconducting coil that generates the static magnetic field is cooled by a normal power source or an emergency power source.
maintaining a power supply relationship in which the cooling unit that cools the superconducting coil is selected as a power supply destination based on monitoring information regarding monitoring of a state of power supply by the normal power supply when the emergency power supply is a power supply source;
The power supply control method includes the steps of:

1 MRI device 2 MRI device 3 Regular power supply 4 MRI device 5 Emergency power supply 7 Power supply system changeover switch 11 Imaging system 12 Uninterruptible power supply (UPS)
13 System transformer 15 Static magnetic field generating unit 17 Imaging system power supply switch 18 Power supply system changeover switch 51 Power supply monitoring device 111 Gradient magnetic field power supply 113 RF amplifier 115 Reconstruction unit 151 Cooling vessel 152 Superconducting coil 153 Refrigerator 155 Compressor 157 Cold head 159 Refrigerator monitoring device

Claims (12)

a cooling unit for cooling a superconducting coil that generates a static magnetic field;
A load different from the cooling unit;
a switching unit that switches between a first state in which power is supplied to the cooling unit and the load from a commercial power source and power is not supplied to the cooling unit and the load from an emergency power source different from the commercial power source, and a second state in which power is supplied to the cooling unit from the emergency power source and power is not supplied to the load from the emergency power source and power is not supplied to the cooling unit and the load from the commercial power source ,
The switching unit is
a first switch unit that switches between a third state in which power is supplied to the cooling unit from the commercial power source and power is not supplied to the cooling unit from the emergency power source and a fourth state in which power is supplied to the cooling unit from the emergency power source and power is not supplied to the cooling unit from the commercial power source;
a second switch unit that switches between a fifth state in which power is supplied to the load and a sixth state in which power is not supplied to the load,
the second switch section is in the fifth state when the first switch section is in the third state, and in the sixth state when the first switch section is in the fourth state;
Magnetic resonance imaging device. a cooling unit for cooling a superconducting coil that generates a static magnetic field;
A load different from the cooling unit;
a switching unit that switches between a first state in which power is supplied to the cooling unit and the load from a commercial power source and power is not supplied to the cooling unit and the load from an emergency power source different from the commercial power source, and a second state in which power is supplied to the cooling unit from the emergency power source and power is not supplied to the load from the emergency power source and power is not supplied to the cooling unit and the load from the commercial power source ,
the switching unit includes a switch unit that switches between a third state in which power is supplied to the cooling unit from the commercial power source and power is not supplied to the cooling unit from the emergency power source, and a fourth state in which power is supplied to the cooling unit from the emergency power source and power is not supplied to the cooling unit from the commercial power source;
the commercial power supply is electrically connected to the load regardless of whether the switch unit is in the third state or the fourth state;
Magnetic resonance imaging device. 3. The magnetic resonance imaging apparatus according to claim 1 , wherein the switching unit switches from the first state to the second state when the supply of power from the commercial power source is stopped. The magnetic resonance imaging apparatus according to claim 1 , wherein the switching unit switches from the second state to the first state when the supply of power from the commercial power source is restored. a detection unit that detects whether or not the supply of power from the commercial power source has been stopped, the detection unit being electrically connected to the first switch unit via an isolation transformer;
A detection result of the detection unit is output to the second switch unit via the isolation transformer.
2. A magnetic resonance imaging apparatus according to claim 1 . 6. The magnetic resonance imaging apparatus according to claim 1 , wherein the cooling unit has a refrigerator that cools a refrigerant for cooling the superconducting coil. 6. The magnetic resonance imaging apparatus according to claim 1 , wherein the cooling unit further comprises a water cooling device that water-cools a refrigerant for cooling the superconducting coil, or an air cooling device that air-cools the refrigerant. 8. The magnetic resonance imaging apparatus according to claim 1 , wherein the emergency power supply is a power supply independent of the commercial power supply and includes a generator. The magnetic resonance imaging apparatus according to claim 8 , wherein the emergency power supply generates a three-phase alternating current. The magnetic resonance imaging apparatus according to claim 1 , wherein the load is a gradient magnetic field unit that applies a gradient magnetic field to the subject. 10. The magnetic resonance imaging apparatus according to claim 1, wherein the load is an RF amplifier that generates an RF signal to be applied to the subject. The magnetic resonance imaging apparatus according to claim 1 , wherein the load is a generator that generates an image based on a magnetic resonance signal generated by a subject.