JP2022076271A - Magnetic resonance imaging system and power supply control method - Google Patents

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

The embodiments disclosed herein and in the drawings relate to magnetic resonance imaging systems and power supply control methods.

Conventionally, in a magnetic resonance imaging device (hereinafter referred to as an MRI (Magnetic Resonance Imaging) device) having a superconducting static magnetic field magnet (superconducting coil), in order to prepare for a power failure, for example, in hospital equipment, etc., separately from the commercial power supply. It is possible to prevent quenching by arranging a unique power supply for power failure (emergency power supply) and switching the power supply from the commercial power supply to the emergency power supply in the event of a power failure. However, when using an emergency power supply, the power capacity required for the emergency power supply is increased due to the generation of inrush current (for example, several times the rated current) in the system transformer of the MRI device and the operation of the entire MRI device. It may be several times larger than the rated time. Therefore, there is a problem that the cost of the emergency power supply increases because the operation of the emergency power supply is guaranteed.

Based on these facts, when the emergency power supply is in operation, for example, in a power saving mode that cuts off the power supply to the image pickup system in the MRI system, and in order to prevent the excitation inrush current due to the residual magnetic flux in the system transformer, the MRI device and commercial products are used. An uninterruptible power supply (hereinafter referred to as UPS) may be provided between the power supply and the MRI device. However, when the power saving mode is activated by the signal emitted by the UPS due to a momentary power failure or a voltage drop, there is a problem that the inspection is interrupted and the inspection throughput is lowered.

International Publication No. 2013-172148

One of the problems to be solved by the embodiments disclosed in the present specification and the drawings is to improve the inspection throughput in the magnetic resonance imaging system. However, the problems to be solved by the embodiments disclosed in the present specification and the drawings are not limited to the above problems. The problem corresponding to each effect by each configuration shown in the embodiment described later can be positioned as another problem.

The magnetic resonance imaging system according to the embodiment can be switched between a regular power supply and an uninterruptible power supply as a power supply 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 operating these components, such as a chiller required for water-cooling the components. The imaging system relates to imaging a subject using the static magnetic field. The switch cuts off the power supply from the power supply source to the image pickup system. The switch control unit controls the switch based on the start information of the power supply from the uninterruptible power supply. The switch control unit controls the switch so as to cut off the power supply to the image pickup system when the power failure in the normal power supply continues for the first time, and enables power-saving operation.

FIG. 1 is a block diagram showing an example of a magnetic resonance imaging system in an ON state (when closed) of an imaging system power supply switch according to an embodiment. FIG. 2 is a block diagram showing an example of an MRI system in an OFF state (when the image pickup system power supply switch is open) according to the embodiment. FIG. 3 is a flowchart showing an example of the procedure of the switching control process according to the embodiment. FIG. 4 is a diagram showing an example of the relationship between the UPS output power (also referred to as apparent power) with respect to the backup time during which the UPS can operate with respect to the UPS according to the embodiment.

Hereinafter, embodiments of a magnetic resonance imaging system and a power supply control method capable of switching between a regular power supply and an uninterruptible power supply as a power supply source will be described in detail with reference to the drawings. FIG. 1 shows a magnetic resonance imaging system in a state in which a switch (hereinafter referred to as an imaging system power supply switch) SW for switching the presence / absence of power supply to the imaging system 11 regarding imaging of a subject using a static magnetic field is ON (when closed). It is a block diagram which shows an example of (hereinafter, referred to as an MRI (Magnetic Response Imaging) system) 1. The technical idea in this embodiment is based on the MRI device 10 having the switch control circuit 7, the uninterruptible power supply device (hereinafter referred to as UPS) 5, and the MRI device 10 having the switch control circuit 7. It may be realized.

The MRI system 1 includes a UPS 5, a switch control circuit 7, and an MRI apparatus 10. The UPS 5 is provided between the regular power supply 3 and the MRI apparatus 10 in, for example, a power supply line from the regular power supply 3 to the MRI apparatus 10. The UPS 5 may be provided outside the MRI system 1. At this time, the MRI system 1 has a switch control circuit 7 and an MRI apparatus 10.

The regular power supply 3 corresponds to an equipment power supply in a hospital or the like where the MRI system 1 is installed, that is, a commercial power supply. The regular power supply 3 supplies electric power to the MRI system 1. At this time, the electric power supplied from the normal power supply 3 is supplied to all the units of the MRI apparatus 10, for example, the imaging system 11 and the static magnetic field generating unit 15 via the system transformer 13 in the MRI apparatus 10. The electric power supplied from the normal power supply 3 is also supplied to other units such as a console and a sleeper (not shown) that are not involved in cooling the superconducting coil 152. Further, the electric power supplied from the regular power source 3 is used for charging the UPS 5.

UPS 5 has a secondary battery and a power supply monitoring device 51. The secondary battery supplies electric power to the MRI apparatus 10 at the time of a power failure including, for example, a momentary power failure (also referred to as a momentary power failure) in the normal power supply 3. The secondary battery is charged by the supply of electric power from the normal power source 3 during the non-power failure of the normal power source 3. The power supply monitoring device 51 functions as a monitor for monitoring the state of power supply to the MRI device 10 by the regular power supply 3.

The power supply monitoring device 51 outputs power supply start information (hereinafter referred to as power supply start information) from the UPS 5 to the MRI device 10 to the switch control circuit 7. The power supply start information is, for example, the time at which the power failure starts, that is, the time when the power failure occurs (hereinafter, referred to as the power failure occurrence time), and is information indicating the occurrence of the power failure. Further, the power supply monitoring device 51 outputs information indicating the start of power recovery of the normal power supply 3 after a power failure of the normal power supply 3 (hereinafter, referred to as power recovery start information) to the switch control circuit 7. The power recovery start information is, for example, the time when the power supply 3 recovers from a power failure (hereinafter referred to as the power recovery time), that is, the time when the power recovery starts, and is information indicating the power recovery of the power supply 3.

The MRI system 1 may be electrically connected to an emergency power supply that is independent of the normal power supply 3 via a power supply system changeover switch that switches the power supply system. The emergency power source has, for example, a generator and a generator that produces a three-phase alternating current. At this time, in the MRI system 1, the normal power supply 3 and the emergency power supply can be switched to each other as the power supply source by switching the power supply system changeover switch. At this time, the MRI system 1 may have a power supply system changeover switch and an emergency power supply. The power system changeover switch switches the connection destination of energization with the MRI device 10 between the normal power supply 3 and the emergency power supply based on the information output from the power supply monitoring device 51 indicating the occurrence of a power failure.

For example, when a power failure occurs in the normal power supply 3, the power supply system changeover switch switches the connection destination of energization with the MRI device 10 from the normal power supply 3 to the emergency power supply. During the duration of the power failure of the working power source 3 from the time of the power failure of the working power source 3 to the time when the switching to the emergency power source is completed, the power supply to the MRI apparatus 10 is executed by the UPS 5. Further, when the normal power supply 3 is restored, the power supply system changeover switch switches the connection destination of the energization with the MRI device 10 from the emergency power supply to the normal power supply 3. At this time, the regular power supply 3 supplies electric power to the MRI system. In addition, the UPS 5 charges the secondary battery by supplying electric power from the regular power source 3.

FIG. 2 is a block diagram showing an example of the MRI system 1 in the OFF state (when the image pickup system power supply switch SW is open). The difference from FIG. 1 is that the image pickup system power supply switch SW is released. The image pickup system power supply switch SW is opened, for example, when the power failure of the normal power supply 3 continues for the first time t1, that is, the first time t1 elapses from the power failure occurrence time in the power failure period of the normal power supply 3. At that time, it is executed by the control by the switch control circuit 7. The first time t1 will be described later.

The switch control circuit 7 controls the image pickup system power supply switch SW based on the power supply start information from the UPS 5, that is, the power supply start information. For example, the switch control circuit 7 controls the image pickup system power supply switch SW so as to cut off the power supply to the image pickup system 11 when the power failure in the normal power supply 3 continues for the first time t1. As a result, the MRI system 1 enables operation with low power consumption. Specifically, the switch control circuit 7 supplies a current to the contact drive coil CC of the relay 17 when the first time t1 elapses from the power failure occurrence time in the power failure period of the normal power supply 3. At this time, the image pickup system power supply switch SW is opened by the operation of the movable contact in the relay 17.

As a result, the UPS 5 supplies power to the cooling unit and the imaging system 11 described later while the power failure of the normal power supply 3 continues for the first time t1, and the power failure of the normal power supply 3 is the first time t1. After continuing for, power is supplied only to the cooling unit. 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 operating these components, such as a chiller required for water-cooling the components.

The switch control circuit 7 controls the image pickup system power supply switch SW based on the power recovery start information. For example, in the switch control circuit 7, after the power supply to the image pickup system 11 by the image pickup system power supply switch SW is cut off, that is, after the image pickup system power supply switch SW is opened, the power recovery in the normal power supply 3 is performed in the second time t2. If the continuation is continued, the image pickup system power supply switch SW is further controlled so that the power is supplied to the image pickup system 11.

Specifically, the switch control circuit 7 stops supplying current to the contact drive coil CC of the relay 17 when the power recovery continues for the second time t2 from the power recovery time. At this time, the movable contact in the image pickup system power supply switch SW moves to the closed position in contact with the fixed contact due to the urging by the elastic body in the relay 17, that is, the urging of the movable contact to the fixed contact. As a result, the image pickup system power supply switch SW is closed. As a result, the normal power supply 3 supplies power to the cooling unit while the power recovery of the normal power supply 3 continues for the second time t2, and the power recovery of the normal power supply 3 continues for the second time t2. After continuing, power is supplied to the cooling unit and the image pickup system 11. The second time t2 will be described later. Further, the process related to the control of the relay 17 by the switch control circuit 7 (hereinafter, referred to as a switching control process) will be described in detail later.

The first time t1 and the second time t2 are the inductance (hereinafter referred to as coil inductance) L of the contact drive coil CC related to the image pickup system power supply switch SW, and from the switch control circuit 7 to the contact drive coil CC. It may be set in an analog manner based on the resistance (hereinafter referred to as switch-related resistance) R of the cable and the contact drive coil CC. Specifically, assuming that the first time t1 is the time τa from the power supply stop to the operation stop in the MRI apparatus 10, the contact drive coil determined by the time constant of the ratio L / R of the coil inductance L to the switch-related resistance R. The operating time τb is set to be larger than τa.

The time τa from the power supply stop to the operation stop in the MRI apparatus 10 is determined by a time constant indicating the degree of the power ON / OFF reaction in the unit after the system transformer 13 in the MRI apparatus 10. Further, the contact drive coil operating time τb determined by the time constant L / R corresponds to a time constant indicating the degree of reaction of the switching operation in the image pickup system power supply switch SW. In other words, the first time t1 is set to be larger than τa (t1> τa).

When the switch control circuit 7 is realized by an analog circuit, the analog circuit depends on the selection of the ratio L / R of the inductance to the resistance in the switch control circuit 7, the operating point of the contact drive coil CC, and the constants of the coil and the resistance. , Appropriately configured. At this time, the first time t1 and the second time t2 are substantially equal to each other. From these facts, when a power failure occurs in the normal power supply 3, for example, after the voltage in the MRI apparatus 10 drops to a predetermined voltage, the image pickup system power supply switch SW is opened. 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.

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 normal power supply 3. That is, the first time t1 includes a period of 1/2 cycle to several seconds at a certain point in the power system of the MRI apparatus 10 and a time corresponding to a momentary interruption defined by a continuous sudden voltage drop. In other words, the first time t1 includes the duration of a short power outage that exceeds the momentary interruption. The first time t1 is not limited to the above 1 minute, and may be 1 minute or more. Further, the first time t1 and the second time t2 may be digitally controlled so as to 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.

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

The image pickup system 11 relates to an image pickup of a subject. That is, the image pickup system 11 has various units related to the image pickup. The various units include, for example, a transmission circuit equipped with a gradient magnetic field power supply 111 for generating a gradient magnetic field for position identification, a gradient magnetic field coil, and an RF amplifier 113 for supplying energy for causing a magnetic resonance phenomenon, and transmission. It has a 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 a magnetic resonance phenomenon. Each component in the image pickup system 11 will be described later.

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

The static magnetic field generation unit 15 has a superconducting coil 152 formed in a hollow substantially cylindrical shape, and generates a static magnetic field in the internal space. The static magnetic field generated by the static magnetic field generation unit 15 is generated by the superconducting magnet. The superconducting magnet is realized by supplying an electric current to the superconducting coil 152 in the cooling container 151 in a superconducting state. The cooling container 151 is formed in a substantially cylindrical shape and is housed in a cylindrical wall of a vacuum container (not shown). As a general example, the cooling container 151 accommodates a liquid helium and a superconducting coil 152 in a cylindrical wall in order to keep the inside of the container at a sufficiently low temperature. In the cooling container 151, the liquid helium and the helium gas in which the liquid helium is vaporized are in an equilibrium state.

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 adjustment is, for example, to prevent an unintended inflow of air into the cooling container 151. When the helium gas in the cooling container 151 is excessively cooled, the proportion of liquid helium in the cooling container 151 increases, and the pressure in the cooling container 151 decreases. When the pressure in the cooling container 151 drops and becomes a negative pressure, air flows into the cooling container 151. The heater is controlled by the refrigerator monitoring device 159 so that the pressure in the cooling container 151 is within a preset range, and warms the helium in the cooling container 151.

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

The compressor 155 compresses a refrigerant gas such as helium gas by 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, an inverter drive. Further, the compressor 155 recovers the refrigerant gas expanded inside the cold head 157 via the discharge pipe. Further, the compressor 155 is connected to a buffer tank filled with the 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 takes in the refrigerant gas filled in the buffer tank through the intake valve.

The cold head 157 expands the high-pressure refrigerant gas supplied through the supply pipe to cool the refrigerant in the cooling container 151. As a result, the cold head 157 cools the refrigerant to a temperature equal to or lower than the boiling point of the refrigerant. When the cooling container 151 is cooled to a certain level or more, the helium gas in the cooling container 151 is recondensed into liquid helium. In addition, in FIG. 1 and FIG. 2, the case where one cold head 157 is installed in the cooling container 151 is shown as an example, but the number of cold heads 157 is not limited to one and may be a plurality.

The vent valve and the intake valve are provided in 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 according to the instruction from the refrigerator monitoring device 159. By exhausting the refrigerant gas in the compressor 155, the pressure of the refrigerant gas supplied from the compressor 155 to the cold head 157 is reduced. The intake valve supplies the refrigerant gas filled in the buffer tank to the compressor 155 according to the instruction from the refrigerator monitoring device 159. By supplying the refrigerant gas to the compressor 155, the pressure of the refrigerant gas supplied from the compressor 155 to the cold head 157 increases.

Up to this point, an example in which helium (He) is required as a refrigerant for magnet cooling has been described, but this embodiment is an MRI system having a conduction cooling type magnet that does not use a refrigerant and a magnet that uses an extremely small amount of refrigerant for magnet cooling. It is also applicable to 1.

The refrigerator monitoring device 159 monitors the refrigerant in the refrigerator 153 and the cooling container 151. For example, the refrigerator monitoring device 159 monitors the pressure in the cooling container 151 and controls the heater so that the pressure in the cooling container 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 the intake valve so that the pressure is within a predetermined range.

The relay 17 is provided between the system transformer 13 and a plurality of units related to power supply in the image pickup system 11. That is, the relay 17 is provided in front of the power supply line to a plurality of units such as the gradient magnetic field power supply 111 which is not involved in the cooling of the static magnetic field generation unit 15. The relay 17 has an image pickup system power supply switch SW and a contact drive coil CC that functions as an electromagnet. The relay 17 is also referred to as a relay.

The relay 17 opens the image pickup system power supply switch SW according to the current output from the switch control circuit 7. The image pickup system power supply switch SW cuts off the power supply from the power supply source to the image pickup system 11. The image pickup system power supply switch SW is, for example, a normally closed contact (Normally Close). That is, when no current is output from the switch control circuit 7, the movable contact in the image pickup system power supply switch SW is urged to the fixed contact by, for example, an elastic body, and is in a closed state.

The contact drive coil CC receives a current supply from the switch control circuit 7 to generate a magnetic field. The contact of the image pickup system power supply switch SW is opened by the generation of the magnetic field. When the current supply from the switch control circuit 7 is cut off when the image pickup system power supply switch SW is open, the magnetic field generated by the contact drive coil CC disappears, and the image pickup system power supply switch SW is closed.

Note that, in FIGS. 1 and 2, the plurality of 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, for example. It may further have other units related to the image pickup system 11 such as a sleeper. As shown in FIG. 1, the image pickup system power supply switch SW is closed (closed) when the power is supplied from the normal power supply 3. Therefore, power is supplied to all the units in the MRI apparatus 10 from the regular power supply 3.

On the other hand, the image pickup system power supply switch SW is a switch based on the power supply start information sent from the UPS 5 after the lapse of the first time t1 from the time when the power failure occurs when the power supply by the regular power supply 3 is stopped, that is, the power failure occurs. As shown in FIG. 2, it is opened (opened) by the control of the control circuit 7. As a result, in the event of a power failure of the regular power supply 3, the electric power supplied from the UPS 5 is supplied only to the unit necessary for cooling the superconducting coil 152.

Hereinafter, the components included in the image pickup system 11 will be briefly described.

The gradient magnetic field coil is a hollow coil formed in a substantially cylindrical shape, and is arranged on the inner surface side of the cylindrical cooling container 151. The gradient magnetic field coil generates a gradient magnetic field in which the magnetic field strength changes along the X, Y, and Z axes orthogonal to each other.

The gradient magnetic field power supply 111 supplies a current to the gradient magnetic field coil under the control of the sequence control circuit in the MRI apparatus 10 by the electric power supplied through the system transformer 13 and the image pickup system power supply switch SW.

The transmission coil receives an RF (Radio Frequency) pulse from the transmission circuit to generate a high frequency magnetic field in the imaging space in the MRI apparatus 10.

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 oscillation unit, a phase selection unit, a frequency conversion unit, an amplitude modulation unit, an RF amplifier 113, and the like. The oscillating unit generates an RF pulse having a resonance frequency peculiar to the target nucleus in a static magnetic field. The phase selection unit selects the phase of the RF pulse generated by the oscillation unit. 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 by the power supplied via the system transformer 13 and the image pickup system power supply switch SW, and supplies the RF pulse to the transmission coil.

The receiving coil is arranged inside the gradient magnetic field coil and receives the MR signal emitted from the subject by the influence of the high frequency magnetic field. The receiving coil outputs the received MR signal to the receiving circuit. It should be noted that a configuration in which the receiving coil is also used as the transmitting coil may be adopted.

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

The sequence control circuit captures an image of a subject by driving a gradient magnetic field power supply 111, a transmission circuit, and a reception circuit based on sequence information transmitted from a computer system. 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.

The sleeper is provided with a top plate on which the subject is placed. The sleeper is composed of an actuator such as a top plate and various motors for driving the sleeper, and a power transmission unit for transmitting the power generated by the actuator to a movable portion. The sleeper and top plate are moved in the longitudinal and vertical directions of the top plate under the control of a computer system.

The computer system controls the entire MRI apparatus 10 and generates MR images. The computer system includes, for example, a network interface, a storage circuit, a processing circuit, an input interface, a display, and the like.

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

The input interface accepts various instructions (for example, power-on instructions) and information input from the operator. The input interface is, for example, a trackball, a switch button, a mouse, a keyboard, a touch pad for input operation by touching the operation surface, a touch screen in which a display screen and a touch pad are integrated, and a non-contact using an optical sensor. It is realized by an input circuit, a voice input circuit, and the like. The input interface is connected to the processing circuit, converts the input operation received from the operator into an electric signal, and outputs the input operation to the processing circuit. In the present specification, the input interface is not limited to the one provided with physical operation parts such as a mouse and a keyboard. For example, an example of an input interface includes 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.

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

The processing circuit controls the entire MRI apparatus 10. More specifically, the processing circuit includes, for example, an image pickup control function, a reconstruction function, and the like. The processing circuit that realizes the reconstruction function is an example of the reconstruction unit 115. Each function such as an image pickup control function and a reconstruction function is stored in a storage circuit in the form of a program that can be executed by a computer. The processing circuit is a processor. For example, the processing circuit realizes the function corresponding to each program by reading the program from the storage circuit and executing the program. In other words, the processing circuit in the state where each program is read out has each function such as an image pickup control function and a reconstruction function.

In the above description, an example in which the "processor" reads a program corresponding to each function from the storage circuit and executes the program has been described, but the embodiment is not limited to this. The word "processor" is used, for example, a CPU, a GPU (Graphics Processing Unit), an integrated circuit for a specific application (Application Specific Integrated Circuit: ASIC), a programmable logic device (for example, a simple programmable logic device (Simple Programbulge)). , Complex Programmable Logic Device (CPLD), and Field Programmable Gate Array (FPGA)) and the like.

When the processor is, for example, a CPU, the processor realizes a function by reading and executing a program stored in a storage circuit. On the other hand, when the processor is an ASIC, the function is directly incorporated as a logic circuit in the circuit of the processor instead of storing the program in the storage circuit. It should be noted that each processor of the present embodiment is not limited to the case where each processor is configured as a single circuit, and a plurality of independent circuits may be combined to form one processor to realize its function. good. Further, although it has been described that a single storage circuit stores a program corresponding to each processing function, a plurality of storage circuits are distributed and arranged, and the processing circuit reads the corresponding program from each storage circuit. It doesn't matter.

The image pickup control function controls each part of the MRI apparatus 10 to perform the image pickup of the magnetic resonance image. More specifically, the imaging control function performs sequence information generation, MR data collection, and the like.

The reconstruction function executes the generation of k-space data and the generation of a magnetic resonance image by the electric power supplied through the system transformer 13 and the image pickup system power supply switch SW. The reconstruction function performs image reconstruction processing by two-dimensional or three-dimensional Fourier transform on the generated k-space data to generate a magnetic resonance image. The reconstruction function stores the generated magnetic resonance image in, for example, a storage circuit.

The switching control process executed by the MRI system 1 of the present embodiment configured as described above will be described with reference to FIG. 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, it is assumed that the normal power supply 3 is in a non-power failure state. Further, it is assumed that no current is supplied to the relay 17, and the movable contact in the image pickup system power supply switch SW is urged to the fixed contact by an elastic body. That is, it is assumed that the image pickup system power supply switch SW is in a normally closed contact state, that is, in a closed state. The process in this flowchart is always executed, for example, when the MRI apparatus 10 is energized after the MRI system 1 is installed.

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

(Step S302)
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 switches from the normal power supply 3 to the UPS 5 when the normal power supply 3 fails.

(Step S303)
If the power failure does not continue from the power failure occurrence time to the first time t1 (No in step S303), the process of step S304 is executed. If the power failure continues from the power failure occurrence time to the first time t1 (Yes in step S303), the step S306 process 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 failure continues from the time when the power failure occurs to the first time t1. If the power failure does not continue from the time when the power failure occurs to the first time t1 (Yes in step S303), the switch control circuit 7 supplies a current to the contact drive coil CC of the relay 17.

(Step S304)
If the power supply monitoring device 51 in the UPS 5 does not detect the power recovery in the normal power supply 3 (NO in step S304), the process of step S303 is executed. If the power supply monitoring device 51 detects that the power is restored in the normal power supply 3 (YES in step S304), the process of step S305 is executed.

(Step S305)
With the detection of the power recovery in step S304, the power supply source to the MRI apparatus 10 is switched from the UPS 5 to the regular power supply 3. At this time, the UPS 5 starts charging the secondary battery by supplying electric power from the normal power source 3. After this step, the process of step S301 is executed.

(Step S306)
The image pickup 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. As a result, the contact drive coil CC generates a magnetic field as an electromagnet and attracts movable contacts. By the operation of the movable contact, the image pickup system power supply switch SW is opened, and the power supply from the power supply source to the image pickup system 11 is cut off. In other words, the electric power from the UPS 5 is supplied only to the cooling unit.

(Step S307)
If the power supply monitoring device 51 does not detect the power recovery in the normal power supply 3 (NO in step S307), this step is repeated. If the power supply monitoring device 51 detects that the power is restored in the normal power supply 3 (YES in step S307), the process of step S308 is executed. Upon the detection of the power recovery, the power supply monitoring device 51 outputs the power recovery start information, that is, the power recovery time, to the switch control circuit 7.

(Step S308)
If the power recovery is not continued from the power recovery time to the second time t2 (No in step S308), the process of step S309 is executed. If the power recovery continues from the power recovery time to the second time t2 (Yes in step S308), the step S310 process is executed. For example, when the switch control circuit 7 is realized by the processor, the switch control circuit 7 determines whether or not the power recovery continues for the second time t2 from the power recovery occurrence time. If the power recovery continues from the power recovery time to the second time t2 (Yes in step S308), the switch control circuit 7 stops supplying the current to the relay 17.

(Step S309)
If the power supply monitoring device 51 in the UPS 5 does not detect a power failure in the normal power supply 3 (NO in step S309), the process of step S308 is executed. If the power supply monitoring device 51 detects a power failure in the normal power supply 3 (YES in step S309), the process of step S307 is executed.

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

(Step S311)
The image pickup 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 supply of the current 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 in the image pickup system power supply switch SW comes into contact with the fixed setting due to the urging of the elastic body. As a result, the image pickup system power supply switch SW is closed, and the power supply to the image pickup system 11 is resumed. By this step, the electric power from the normal power source 3 is supplied to the cooling unit and the image pickup system 11. By this step, the switching control process shown in FIG. 3 is completed. 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.

The MRI system 1 according to the above-described embodiment has a cooling unit that can switch between a regular 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. Based on the image pickup system 11 related to image pickup of a subject using a static magnetic field, the image pickup system power supply switch SW that cuts off the power supply from the power supply source to the image pickup system 11, and the start information of the power supply from the uninterruptible power supply. A switch control unit that controls the power supply switch SW of the image pickup system is provided, and the switch is controlled so as to cut off the power supply to the image pickup system 11 when the power failure in the normal power supply 3 continues for the first time t1. do. As a result, according to the present MRI system 1, the UPS 5 supplies power to the cooling unit and the image pickup system 11 while the power failure of the normal power supply 3 continues for the first time t1, and the power failure is the first. After continuing for the time t1 of, power can be supplied only to the cooling unit.

Further, according to the MRI system 1, the first time t1 is based on the inductance L of the contact drive coil CC related to the image pickup system power supply switch SW and the resistance R from the switch control unit to the contact drive coil CC. Can be set. The first time t1 is set, for example, by 1/4 cycle or more and within 1 minute of the frequency of the voltage in the normal power supply 3.

From these facts, according to the present MRI system 1, it is possible to prevent the image pickup system power supply switch SW from being opened due to a short-term voltage drop that keeps the MRI apparatus 10 in a normal state. The short-term voltage drop occurs, for example, due to a momentary interruption due to lightning or the like (for example, a voltage drop of approximately 0.5 to 1 cycle or less in the frequency of the voltage in a commercial power source). The normal state is maintained, for example, that the voltage in the MRI device 10 gradually drops due to the equivalent resistance, inductance, and capacitance of the device in which the voltage drop is the load of the MRI device 10, and that the voltage of the MRI device 10 is maintained. This is due to the fact that the power is charged by the smoothing capacitor provided in the DC power supply of each unit, and the transmission line is switched immediately for the power supply due to a momentary power failure such as a momentary power failure.

From these facts, according to the present MRI system 1, by preventing the image pickup system power supply switch SW from being opened due to a momentary interruption, the power supply to each unit related to the image pickup system 11 is accompanied by the power supply of each unit. It is not necessary to restart the subject, and it is possible to omit the waiting time of the subject by retracting the subject from the MRI apparatus 10 at the restart. In other words, according to this MRI system 1, there is a momentary interruption in which the MRI apparatus 10 side can maintain a sufficiently normal state, and a power failure of the regular power supply 3 is about 1 second to, for example, 30 seconds, which is an extremely short period of time. In the case of power recovery, by setting the first time t1 to be larger than the time constant, the power supply of the unit having a large power consumption such as the gradient magnetic field power supply 111 is not stopped, so that the system of the imaging system 11 is down. It is possible to reduce unnecessary waiting time and reduce the non-operating time (downtime) of the MRI apparatus 10.

FIG. 4 is a diagram showing an example of the relationship between the output power (also referred to as apparent power) of UPS 5 with respect to the backup time in which UPS 5 can operate. Hereinafter, for the sake of simplicity, the capacity of the power supplied by the UPS 5 is assumed to be 100 kVA. Further, it is assumed that the required power required by the MRI apparatus 10 at the time of imaging the subject, that is, during normal operation is 100 kVA. Further, it is assumed that the required power at the time of executing the power saving operation in the switching control process is 25 kVA.

As shown in FIG. 4, the UPS 5 can operate in a power saving operation (required power: 25 kVA) at the time of a power failure of the regular power supply 3 with a backup time of about 90 minutes. Further, as shown in FIG. 4, when the power of 100 kVA 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 the backup time (90 minutes) in the power saving operation is allowed to be shortened, for example, in the event of a power failure of the regular power supply 3, the power supply of 100 kVA by the UPS 5 takes about 30 seconds to power all the units in the MRI apparatus 10. Can be supplied.

That is, when the first time t1 is set to 30 seconds, according to the MRI system 1, during the power failure period of the regular power supply 3, the image pickup system 11 in the MRI apparatus 10 is operated for 30 seconds from the start of the power failure. Imaging of the subject can be performed without system down. At this time, when the power failure time in the normal power supply 3 exceeds 30 seconds, the MRI system 1 can supply power from the UPS 5 only to the cooling unit related to the cooling of the superconducting coil 152 by the power saving operation.

From the above, according to the present MRI system 1, for example, even if the MRI apparatus 10 can be continuously used due to a short-term voltage drop of less than one cycle of the commercial power supply, the image pickup system power supply switch SW Since it is possible to prevent the system from entering the power saving mode, it is possible to avoid interruption of the inspection due to a momentary interruption. Therefore, according to the present MRI system 1, it is possible to improve the throughput (test efficiency) of the test relating to the subject.

Further, in the MRI system 1 according to the embodiment, when the power restoration in the normal power supply 3 continues for the second time t2 after the power supply to the image pickup system 11 is cut off by the image pickup system power supply switch SW, the image pickup is performed. The imaging system power supply switch SW is controlled so that power is supplied to the system 11. 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 the power recovery is performed in the second time t2. After that, power can be supplied to the cooling unit and the imaging system 11. Further, according to the present MRI system 1, the second time t2 is based on the inductance L of the contact drive coil CC related to the image pickup system power supply switch SW and the resistance R from the switch control unit to the contact drive coil CC. It can also be set in an analog manner. For example, the second time t2 is shorter than the first time t1.

From these facts, according to the MRI system 1 according to the embodiment, the number of cycles related to power failure and power recovery including a momentary interruption in the normal power supply 3 can be reduced as compared with the conventional case. As a result, the fluctuation of the discharge and charge cycle in UPS 5, that is, the number of times of charge and discharge can be reduced, so that the life of the secondary battery in UPS 5, that is, the life of UPS 5 can be extended. From these facts, according to the MRI system 1 according to the embodiment, it is possible to improve the inspection efficiency and reduce the total cost in the MRI system 1.

When the technical idea in the embodiment is realized by the 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 UPS 5, and the power failure in the normal power supply 3 is the first. When the power supply to the image pickup system 11 regarding the image pickup of the subject using the static magnetic field is continued for the time t1, the image pickup system power supply switch SW is supplied with power from the normal power supply 3 or UPS 5 to the image pickup system 11. Control to disconnect. Since the procedure and effect of the switching control process executed by the power supply control method are the same as those in the embodiment, the description thereof will be omitted.

According to the embodiment described above, the inspection throughput can be improved in the magnetic resonance imaging system 1.

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 embodiments, and various omissions, replacements, changes, and combinations of embodiments can be made without departing from the gist of the invention. These embodiments and variations thereof are included in the scope of the invention described in the claims and the equivalent scope thereof, as are included in the scope and gist of the invention.

Regarding the above embodiments, the following appendices are disclosed as one aspect and selective features of the invention.
(Appendix 1)
It is a magnetic resonance imaging system that can switch between a regular power supply and an uninterruptible power supply as a power supply source.
A cooling unit that cools the superconducting coil that generates a static magnetic field,
An imaging system for imaging a subject using the static magnetic field, and
A switch that disconnects the power supply from the power supply source to the image pickup system,
A switch control unit that controls the switch based on the start information of power supply from the uninterruptible power supply.
Equipped with
The switch control unit controls the switch so as to cut off the power supply to the image pickup system when the power failure in the normal power supply continues for the first time.
Magnetic resonance imaging system.
(Appendix 2)
After the power supply to the image pickup system is cut off by the switch, the switch control unit so as to supply power to the image pickup system when the power recovery in the normal power supply continues for a second time. The switch may be further controlled.
(Appendix 3)
The regular power supply supplies power to the cooling unit while the power recovery continues for the second time, and after the power recovery continues for the second time, the cooling unit and the cooling unit Electric power may be supplied to the image pickup system.
(Appendix 4)
The first time and the second time may be set based on the inductance of the contact driving coil with respect to the switch and the resistance from the switch control unit to the contact driving coil.
(Appendix 5)
The first time and the second time may be set to desired values by digital control.
(Appendix 6)
The first time may be longer than the second time.
(Appendix 7)
The uninterruptible power supply supplies power to the cooling unit and the imaging system while the power failure continues for the first time, and after the power failure continues for the first time, Electric power may be supplied to the cooling unit.
(Appendix 8)
The first time may be 1/4 cycle or more and 1 minute or less of the frequency of the voltage in the regular power supply.
(Appendix 9)
Cool the superconducting coil that generates a static magnetic field with a regular power supply or an uninterruptible power supply.
When the power failure in the regular power supply continues for the first time, the switch for cutting off the power supply to the imaging system for imaging the subject using the static magnetic field is switched from the regular power supply or the uninterruptible power supply. Control to cut off the power supply to the imaging system,
It is a power supply control method.

1 MRI system 3 Regular power supply 5 Uninterruptible power supply (UPS)
7 Switch control circuit 10 MRI device 11 Imaging system 13 System transformer 15 Static magnetic field generation unit 17 Relay
51 Power supply monitoring device 111 Diagonal magnetic field power supply 113 RF amplifier 115 Reconstruction unit 151 Cooling container 152 Superconducting coil 153 Refrigerator 155 Compressor 157 Cold head 159 Refrigerator monitoring device CC Contact drive coil SW Imaging system Power supply switch

Claims (9)

It is a magnetic resonance imaging system that can switch between a regular power supply and an uninterruptible power supply as a power supply source.
A cooling unit that cools the superconducting coil that generates a static magnetic field,
An imaging system for imaging a subject using the static magnetic field, and
A switch that disconnects the power supply from the power supply source to the image pickup system,
A switch control unit that controls the switch based on the start information of power supply from the uninterruptible power supply.
Equipped with
The switch control unit controls the switch so as to cut off the power supply to the image pickup system when the power failure in the normal power supply continues for the first time.
Magnetic resonance imaging system. After the power supply to the image pickup system is cut off by the switch, the switch control unit so as to supply power to the image pickup system when the power recovery in the normal power supply continues for a second time. Further control the switch,
The magnetic resonance imaging system according to claim 1. The regular power supply is
While the power recovery continues for the second time, power is supplied to the cooling unit.
After the power recovery continues for the second time, power is supplied to the cooling unit and the image pickup system.
The magnetic resonance imaging system according to claim 2. The first time and the second time are set based on the inductance of the contact driving coil with respect to the switch and the resistance from the switch control unit to the contact driving coil.
The magnetic resonance imaging system according to claim 2 or 3. The first time and the second time can be set to desired values by digital control.
The magnetic resonance imaging system according to claim 2 or 3. The first time is longer than the second time.
The magnetic resonance imaging system according to any one of claims 2 to 5. The uninterruptible power supply
While the power failure continues for the first time, power is supplied to the cooling unit and the imaging system.
After the power failure continues for the first time, power is supplied to the cooling unit.
The magnetic resonance imaging system according to any one of claims 1 to 6. The first time is 1/4 cycle or more and 1 minute or less of the frequency of the voltage in the regular power supply.
The magnetic resonance imaging system according to any one of claims 1 to 5. Cool the superconducting coil that generates a static magnetic field with a regular power supply or an uninterruptible power supply.
When the power failure in the regular power supply continues for the first time, the switch for cutting off the power supply to the imaging system for imaging the subject using the static magnetic field is switched from the regular power supply or the uninterruptible power supply. Control to cut off the power supply to the imaging system,
It is a power supply control method.

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