JP5345325B2 - Magnetic resonance imaging apparatus and RF power amplification apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a magnetic resonance imaging apparatus and a radio frequency or RF power amplifier for suppressing unnecessary heat generation produced by an amplifier and for stably amplifying power. <P>SOLUTION: An imaging region of a subject 40 is inputted into an operational part 32, and the size of electric power to be outputted to the RF power amplifier 221 is determined from the imaging region of the subject 40. Then, an amplification ratio of the electric power amplified by the RF power amplifier 221 is calculated in accordance with the determined size of the electric power, and the amplifier 2211 used for amplifying the electric power is determined. Change-over of the switch 2212 in the RF power amplifier 221 is carried out. <P>COPYRIGHT: (C)2009,JPO&amp;INPIT

Description

  The present invention relates to a magnetic resonance imaging apparatus (MRI) and an RF power amplification apparatus.

  A magnetic resonance imaging apparatus is an apparatus that takes a tomographic image of a subject by generating a magnetic resonance signal using a nuclear magnetic resonance phenomenon.

In order to generate a magnetic resonance signal, an RF signal is applied to an RF coil, and the subject is irradiated with an RF pulse from the RF coil. At this time, if the power of the RF signal generated by the RF oscillator is increased, a high-performance RF oscillator is required, and the power consumption of the RF oscillator is increased. Therefore, an amplifier such as a power amplifier is used to amplify the power of the RF signal generated by the RF oscillator (see, for example, Patent Document 1).

JP 2007-190362 A (see, for example, paragraph 0026)

  However, the magnitude of the RF pulse irradiated to the subject from the RF coil varies depending on, for example, a region where a tomographic image of the subject is captured. For example, if the area to be imaged is wide, the number of protons that are excited increases, so that the magnitude of the RF pulse needs to be increased. Therefore, the amplification factor of the power amplified by the power amplifier differs depending on the area to be photographed. However, conventionally, the power is amplified by the same power amplifier having a plurality of amplifiers regardless of the area to be photographed.

  Therefore, for example, when the area to be photographed is small, the power amplification factor may be small. When the power amplifier is amplified using the same power amplifier as that used when the area to be photographed is wide, Wasted heat is generated from amplifiers that may not be used for amplification. Therefore, a stable operation of the amplifier cannot be obtained, and it becomes difficult to obtain a desired amplification factor. In addition, since amplification is performed using a plurality of amplifiers, it is difficult to maintain the linearity of the amplified power due to the addition of variations in the linearity of individual amplifiers.

  Therefore, the present invention provides an RF power amplifying device that suppresses useless heat generation generated from an amplifier and stably amplifies power, and a magnetic imaging device that irradiates a stable RF pulse.

  The present invention amplifies the power input to the power amplifying unit and outputs it to the RF coil to irradiate the imaging region of the subject in the static magnetic field space with the RF pulse, and generate the magnetism generated in the imaging region of the subject. A magnetic resonance imaging apparatus that generates a magnetic resonance image in an imaging region of the subject based on a resonance signal, wherein the power amplification unit includes a plurality of amplifiers that amplify the power, and a plurality of amplifiers And an amplifier switching unit that switches a combination of the amplifiers according to an amplification factor that amplifies the input power, and amplifies the input power based on the amplification factor. , Output to the RF coil.

  Preferably, the power amplification factor calculation unit calculates an amplification factor for amplifying the input power based on the imaging region of the subject, and the amplification factor is calculated by the power amplification factor calculation unit. The

  Preferably, the amplifier switching unit is connected between all of the plurality of adjacent amplifiers.

  Preferably, the amplifier switching unit is a switch.

  Preferably, a cooling unit that cools the power amplification unit is provided, and the cooling unit switches the amplifier by switching between a plurality of amplifier cooling units that cool each of the plurality of amplifiers and the amplifier switching unit. A selection unit that selects the amplifier cooling unit so that only the amplifier used for amplification is cooled, and the amplifier used for amplification of the power by the amplifier cooling unit selected in the selection unit Cooling.

  Preferably, the amplifier cooling unit is a heat absorber that is disposed around each of the plurality of amplifiers and absorbs heat from the amplifier when a refrigerant flows therein, and the selection unit includes the power A control valve that controls the flow of the refrigerant so that the refrigerant flows only in the heat absorber that cools the amplifier used for amplification of the refrigerant.

  Preferably, the amplifier cooler is disposed in contact with each of the plurality of amplifiers.

  Preferably, water is used as the refrigerant.

  Preferably, the amplifier cooling unit is a fan.

  The present invention irradiates an imaging region of a subject in a static magnetic field space with an RF pulse, and generates a magnetic resonance image in the imaging region of the subject based on a magnetic resonance signal generated in the imaging region of the subject. In the magnetic resonance imaging apparatus, an RF power amplifier that amplifies input power and outputs the amplified power to an RF coil, and is connected between the plurality of amplifiers that amplify the input power and the plurality of amplifiers An amplifier switching unit that switches a combination of the amplifiers according to an amplification factor that amplifies the input power, amplifies the input power based on the amplification factor, and the RF coil Output to.

  Preferably, the amplification factor is calculated based on the imaging region in the subject.

  Preferably, the amplifier switching unit is connected between all of the plurality of adjacent amplifiers.

  Preferably, the amplifier switching unit is a switch.

  According to the present invention, it is possible to provide an RF power amplification device that suppresses useless heat generation generated from an amplifier and stably amplifies power, and a magnetic imaging device that irradiates a stable RF pulse.

  Hereinafter, an embodiment according to the present invention will be described with reference to the drawings.

<First Embodiment>
(Device configuration)
FIG. 1 is a configuration diagram showing a configuration of a magnetic resonance imaging apparatus according to an embodiment of the present invention. This apparatus is an example of an embodiment of the present invention.

  As shown in FIG. 1, the magnetic resonance imaging apparatus 1 includes a scan unit 2 and an operation console unit 3. Here, the scan unit 2 includes a static magnetic field magnet (magnet) unit 12, a gradient coil unit 13, an RF coil unit 14, and a cradle 15. The operation console unit 3 includes an RF drive unit 22, a gradient drive unit 23, a data collection unit 24, a control unit 30, a storage unit 31, an operation unit 32, a data processing unit 33, and a display unit 34. And have.

  The scanning unit 2 will be described.

  As shown in FIG. 1, the scan unit 2 includes a static magnetic field space 11 in which an imaging slice region in the subject 40 is accommodated. Based on the control signal from the operation console unit 3, the scanning unit 2 irradiates the imaging region of the subject 40 accommodated in the static magnetic field space 11 in which the static magnetic field is formed, from the imaging region. A scan for acquiring a magnetic resonance signal is performed.

  Each component of the scanning unit 2 will be described sequentially.

  The static magnetic field magnet unit 12 is provided to form a static magnetic field in the static magnetic field space 11 in which the subject 40 is accommodated. The static magnetic field magnet unit 12 is a horizontal magnetic field type, and is a superconducting magnet (z direction) along the body axis direction (z direction) of the subject 40 placed in the static magnetic field space 11 in which the subject 40 is accommodated. (Not shown) forms a static magnetic field. In addition to the horizontal magnetic field type, the static magnetic field magnet unit 12 may be a vertical magnetic field type or a permanent magnet.

  The gradient coil unit 13 forms a gradient magnetic field in the static magnetic field space 11 so that the magnetic resonance signal received by the RF coil unit 14 has three-dimensional position information. The gradient coil unit 13 has three systems of gradient coils to form three types of gradient magnetic fields: a slice selection gradient magnetic field, a read gradient magnetic field, and a phase encoding gradient magnetic field.

  The RF coil unit 14 is arranged so as to surround the subject 40, for example. The RF coil unit 14 transmits an RF pulse, which is an electromagnetic wave, to the subject 40 based on a control signal from the control unit 30 in a static magnetic field space 11 where a static magnetic field is formed by the static magnetic field magnet unit 12 to generate a high frequency. Create a magnetic field. As a result, the spin of protons in the imaging slice region of the subject 40 is excited. The RF coil unit 14 receives, as a magnetic resonance signal, an electromagnetic wave generated when the proton spin in the imaging slice region of the excited subject 40 returns to the original magnetization vector (vector). The RF coil unit 14 may transmit and receive RF pulses using the same RF coil.

  The cradle 15 has a table on which the subject 40 is placed. The cradle 15 moves the subject 40 placed on the table between the inside and outside of the static magnetic field space 11 based on a control signal from the control unit 30.

  The operation console unit 3 will be described.

  The operation console unit 3 controls the scan unit 2 to scan the subject 40 and generates an image of the subject 40 based on the magnetic resonance signal obtained by the scan performed by the scan unit 2. At the same time, the generated image is displayed.

  Each part which comprises the operation console part 3 is demonstrated sequentially.

  FIG. 2 is a block diagram illustrating a configuration of the RF driving unit according to the embodiment of the present invention.

  As shown in FIG. 2, the RF driving unit 22 drives the RF coil unit 14 to transmit RF pulses in the imaging space to form a high-frequency magnetic field, and an RF oscillator (not shown) and a gate (gate) modulation. (Not shown) and an RF power amplifier 221.

  The RF power amplifier 221 receives the power output from the gate modulator, amplifies the input power, and outputs the amplified power to the RF coil unit 14.

  For example, the RF power amplifier 221 includes a plurality of amplifiers 2211 and a switch 2212. The switch 2212 is located between the plurality of amplifiers 2211 and is connected to the amplifier 2211 or is connected to one amplifier 2211. Then, by switching the switch 2212, the amplifier 2211 used for power amplification is selected. The amplifier 2211 used for power amplification is determined based on the amplification factor of the power to be amplified.

  FIG. 3 is a block diagram showing the configuration of the RF power amplifier according to one embodiment of the present invention.

  As shown in FIG. 3, in this embodiment, for example, the RF power amplifier 221 includes an amplifier 2211a, an amplifier 2211b, an amplifier 2211c, a switch 2212a, a switch 2212b, and a switch 2212c. The switch 2212a is located between the amplifier 2211a and the amplifier 2211b, and is connected to the amplifier 2211a and the amplifier 2211b. The switch 2212b is located between the amplifier 2211b and the amplifier 2211c, and is connected to the amplifier 2211b and the amplifier 2211c. The switch 2212c is connected only to the amplifier 2211c. The switches 2212a and 2212b are switches that can be switched in two directions, and the switch 2212c is a switch that can be switched in three directions. By switching the switch 2212a, the switch 2212b, and the switch 2212c, the amplifier 2211 used for power amplification is selected.

Next, the use of the RF power amplifier 221 will be described.
As shown in FIG. 3, for example, when only the amplifier 2211a is used to amplify the power, the switch 2212a is set to the (1) side and the switch 2212c is set to the (1) side. Thus, only the amplifier 2211a can be used. When the amplifier 2211a and the amplifier 2211b are used to amplify power, the changeover switch of the switch 2212a is set to the (2) side, the changeover switch of the switch 2212b is set to the (1) side, and the changeover switch of the switch 2212c. By setting the to the (2) side, the amplifier 2211a and the amplifier 2211b can be used. When the amplifier 2211a, the amplifier 2211b and the amplifier 2211c are used to amplify the power, the switch 2212a is switched to the (2) side and the switch 2212b is switched to the (2) side. By setting the changeover switch of 2212c to the (3) side, the amplifier 2211a, the amplifier 2211b, and the amplifier 2211c can be used.

  The gradient driving unit 23 drives the gradient coil unit 13 based on a control signal from the control unit 30 to generate a gradient magnetic field in the static magnetic field space 11. The gradient drive unit 23 includes three systems of drive circuits (not shown) corresponding to the three systems of gradient coils of the gradient coil unit 13.

  The data collection unit 24 includes a phase detector (not shown) and an analog / digital converter (not shown) in order to collect magnetic resonance signals received by the RF coil unit 14. The data collection unit 24 detects the phase of the magnetic resonance signal from the RF coil unit 14 using the phase detector with the output of the RF oscillator of the RF drive unit 22 as a reference signal, and outputs the detected signal to the analog / digital converter. . Then, the magnetic resonance signal, which is an analog signal phase-detected by the phase detector, is converted into a digital signal by the analog / digital converter and output to the data processing unit 33.

  The control unit 30 includes a computer and a memory that stores a program that causes each unit to execute an operation corresponding to a predetermined scan using the computer. And the control part 30 is connected to the operation part 32 mentioned later, processes the operation signal input into the operation part 32, and is the cradle 15, the RF drive part 22, the gradient drive part 23, and the data collection part 24. Control is performed by outputting a control signal to each unit. Further, the control unit 30 controls the data processing unit 33 and the display unit 34 based on an operation signal from the operation unit 32 in order to obtain a desired image.

  The storage unit 31 includes a computer and a memory that stores a program that causes the computer to execute predetermined data processing. And the memory | storage part 31 memorize | stores the magnetic resonance signal before the image reconstruction process collected by the data collection part 24, the image data by which the image reconstruction process was carried out by the data processing part 33 mentioned later, etc.

  The operation unit 32 includes an operation device (device) such as a keyboard and a mouse. In the operation unit 32, data such as an imaging protocol is input by an operator, and an area for performing an imaging sequence is set. Data relating to the imaging protocol, setting area, and the like is output to the control unit 30.

  The data processing unit 33 includes a computer and a memory that stores a program for executing predetermined data processing using the computer. The data processing unit 33 is connected to the control unit 30 and performs data processing based on a control signal from the control unit 30. The data processing unit 33 is connected to the data collecting unit 24 and performs various image processing on the magnetic resonance signal output from the data collecting unit 24 to generate image data.

  Here, FIG. 4 is a block diagram showing a configuration of a data processing unit in an embodiment according to the present invention.

As shown in FIG. 4, in the present embodiment, the data processing unit 33 includes a power amplification factor calculation unit 331.
The power amplification factor calculation unit 331 calculates the amplification factor of the power that is amplified by the RF power amplifier 221.

  For example, the power amplification factor calculation unit 331 determines the amount of power that is amplified by the RF power amplifier 221 and output to the RF coil unit 14 and the power that is modulated by the gate modulator and input from the gate modulator to the RF power amplifier 221. Based on the magnitude, the amplification factor of the power amplified by the RF power amplifier 221 is calculated.

  The magnitude of the electric power that is amplified by the RF power amplifier 221 and output to the RF coil unit 14 may be input by the operator using the operation unit 32, or based on the imaging region in the subject 40, the control unit 30 may be determined.

  The display unit 34 includes a display device such as a display, and displays an image on the display screen based on a control signal from the control unit 30. The display unit 34 displays, for example, an image of input items for which operation data is input to the operation unit 32 by the operator on the display screen. The display unit 34 displays a slice image of the subject 40 generated by the data processing unit 33.

(Operation)
Hereinafter, an operation when imaging the subject 40 using the magnetic resonance imaging apparatus 1 of the present embodiment will be described.

  FIG. 5 is a flowchart showing scan parameter setting and scanning operations in an embodiment according to the present invention.

  First, as shown in FIG. 5, parameters for imaging the subject 40 are input (ST1010).

  Here, for example, the imaging protocol and the subject 40 are used as parameters when the subject 40 is imaged on the operation data input screen displayed on the display unit 34 by using a keyboard or a mouse that is the operation unit 32. Enter the shooting area, etc. Then, data related to parameters input to the operation unit 32 is input to the control unit 30.

  Next, as shown in FIG. 5, the magnitude of the power output to RF coil section 14 is determined (ST1020).

  Here, the operator or the control unit 30 determines the amount of power to be amplified by the RF power amplifier 221 and output to the RF coil unit 14 based on the data regarding the imaging region in the subject 40 input by the operator in step ST1010. To do.

Specifically, for example, when the magnetic field in the magnetic resonance imaging apparatus 1 is 1.5 T and the imaging region in the subject 40 does not require strong excitation at the head, the RF power amplifier 221 to the RF coil unit 14 The magnitude of the power output to 100 is 100W. When the imaging region in the subject 40 requires strong excitation at the head, the magnitude of the power is 1 kW. Further, when the imaging region in the subject 40 is an abdomen, the magnitude of power is 10 kW.
The magnitude of these electric powers is determined by the operator according to the imaging area of the subject 40, and is input using the operation unit 32. Alternatively, the correspondence between the imaging region and the magnitude of the power output to the RF coil unit 14 is stored in the control unit 30 in advance, and the control unit 30 determines the data such as the imaging region in the subject 40 input by the operator.

  Next, as shown in FIG. 5, the amplification factor of the power to be amplified is calculated (ST1030).

  Here, based on the magnitude of power amplified by the RF power amplifier 221 determined in step ST1020 and output to the RF coil unit 14, and based on the magnitude of power input to the RF power amplifier 221 from the gate modulator, the RF power amplifier The power amplification factor calculation unit 331 calculates the amplification factor of the power amplified by 221.

  For example, when the imaging region in the subject 40 does not require strong excitation at the head, the magnitude of power input to the RF power amplifier 221 is 1 mW, and the magnitude of power output from the RF power amplifier 221. Is 100 W, the amplification factor is 50 dB. When the imaging region in the subject 40 is a head and requires a strong cold machine, the magnitude of power input to the RF power amplifier 221 is 1 mW, and the magnitude of power output from the RF power amplifier 221. Since 1 kW, the amplification factor is 60 dB. Further, when the imaging region of the subject 40 is an abdomen, the magnitude of power input to the RF power amplifier 221 is 1 mW, and the magnitude of power output from the RF power amplifier 221 is 10 kW. The amplification factor is 70 dB.

  Next, as shown in FIG. 5, an amplifier 2211 for amplifying power is determined (ST1040).

  Here, based on the power amplification factor calculated in step ST1030, control unit 30 determines amplifier 2211 that amplifies the power.

Specifically, control unit 30 determines amplifier 2211 to be used for power amplification based on the power amplification factor calculated in step ST1030, the gain of amplifier 2211, the maximum output, and the like.
For example, when the power is amplified by the RF power amplifier 221 shown in FIG. 3, the amplifier 2211a has a power gain of 50 dB, and the amplifier 2211b and the amplifier 2211c have a power gain of 10 dB. Therefore, when the power gain is less than 50 dB, The power is amplified only by the amplifier 2211a. When the power amplification factor is 50 dB or more and less than 60 dB, the amplifier 2211a and the amplifier 2211b amplify the power. When the power amplification factor is 60 dB or more and less than 70 dB, the amplifier 2211a, the amplifier 2211b, and the amplifier 2211c amplify the power. As described above, the control unit 30 determines the amplifier 2211 that amplifies the power based on the power amplification factor.

  For example, when the imaging region in the subject 40 does not require strong excitation at the head, the power amplification factor is 50 dB, and thus the power is amplified by the amplifier 2211a. When the imaging region in the subject 40 requires strong excitation at the head, the power amplification factor is 60 dB, and thus the power is amplified by the amplifier 2211a and the amplifier 2211b. Further, when the imaging region of the subject 40 is an abdomen, the power amplification factor is 70 dB, and therefore the power is amplified by the amplifier 2211a, the amplifier 2211b, and the amplifier 2211c.

  Next, as shown in FIG. 5, switching of the switch 2212 in the RF power amplifier 221 is executed (ST1050).

  Here, the control unit 30 switches the switch 2212 so that the power can be amplified using the amplifier 2211 determined in step ST1040.

  Specifically, in the case of the RF power amplifier 221 shown in FIG. 3, for example, when power is amplified only by the amplifier 2211a, the changeover switch of the switch 2212a is set to the (1) side and the changeover switch (1) of the switch 2212c is set. The control unit 30 outputs a control signal for switching to the switch 2212 to each switch. When the amplifier 2211a and the amplifier 2211b amplify the power, the changeover switch of the switch 2212a is set to the (2) side, the changeover switch of the switch 2212b is set to the (1) side, and the changeover switch of the switch 2212c is set to (2). The control unit 30 outputs a control signal for switching to the switch 2212 to each switch. When the amplifier 2211a, amplifier 2211b, and amplifier 2211c wants to amplify power, switch 2212a is switched to (2), switch 2212b is switched to (2), and switch 2212c is switched. The control unit 30 outputs a control signal for switching the switch to the (3) side to each switch 2212. As described above, the control unit 30 controls the switch 2212 based on the amplifier 2211 used for power amplification.

  Next, as shown in FIG. 5, an RF pulse is irradiated (ST1060).

  Here, the power amplified using the RF power amplifier 221 in which the switch 2212 is switched in step ST1050 is applied to the RF coil unit 14, and the subject 40 is irradiated with RF pulses from the RF coil unit 14.

  Next, as shown in FIG. 5, a magnetic resonance signal is acquired (ST1070).

  Here, the data acquisition unit 24 acquires the magnetic resonance signal from the subject 40 irradiated with the RF pulse in step ST1060. Then, magnetic resonance signals are acquired as imaging data so as to correspond to all the phase encoding steps in the k space.

  Next, the data processing unit 33 performs image reconstruction processing on the acquired magnetic resonance signal, reconstructs an image, and outputs the image to the display unit 34.

  As described above, in one embodiment of the present invention, the imaging region of the subject 40 is input to the operation unit 32, and the magnitude of the power to be output to the RF power amplifier 221 is determined based on the imaging region of the subject 40. . Based on the determined power level and the power level input to the RF power amplifier 221, the amplification factor of the power amplified by the RF power amplifier 221 is calculated, and the amplifier 2211 used to amplify the power. To decide. Then, switching of the switch 2212 in the RF power amplifier 221 is executed. Then, the RF power amplifier 221 that switches the switch 2212 amplifies the power, applies the amplified power to the RF coil unit 14, irradiates the RF pulse from the RF coil unit 14, and acquires a magnetic resonance signal. Then, image reconstruction is performed based on the acquired magnetic resonance signal.

  As described above, the magnitude of the power output to the RF power amplifier 221 differs depending on the imaging region in the subject 40. Accordingly, since the amplification factor of the power amplified by the RF power amplifier 221 is different, by controlling the number of amplifiers 2211 used for amplifying the power based on the amplification factor, the amplifier 2211 used for the amplification of the power. Therefore, the heat generation of the RF power amplifier 221 can be suppressed. Therefore, a stable operation of the amplifier can be obtained and a desired amplification factor can be obtained. Also, by controlling the number of amplifiers 2211, the linearity of the power of the RF signal amplified by the RF power amplifier 221 can be improved. In addition, since a stable operation of the amplifier is obtained, a stable RF pulse can be irradiated in the magnetic resonance imaging apparatus.

<Second Embodiment>
(Device configuration)
FIG. 6 is a block diagram showing the configuration of the magnetic resonance imaging apparatus according to one embodiment of the present invention. This apparatus is an example of an embodiment of the present invention.
The second embodiment is the same as the first embodiment except for the cooling unit that is the configuration of the magnetic resonance imaging apparatus 1. Therefore, description is abbreviate | omitted about the location which overlaps.

  As shown in FIG. 6, the magnetic resonance imaging apparatus 1 has a cooling unit 35.

  The cooling unit 35 will be described.

  The cooling unit 35 cools the heat generated by the RF power amplifier 221. The refrigerant unit 35 may use a refrigerant such as water cooling to cool the RF power amplifier 221 or may be an air cooling type such as a fan.

  FIG. 7 is a configuration diagram showing the configuration of the cooling section in one embodiment according to the present invention.

The cooling unit 35 includes, for example, a heat absorber 35a, a control valve 35b, and a refrigerant cooling unit 35c.
For example, the heat absorber 35 a is arranged around the plurality of amplifiers 2211 so as to cool each of the plurality of amplifiers 2211 in the RF power amplifier 221. Moreover, in order to improve a cooling effect, you may arrange | position and contact. Then, when the refrigerant flows through the heat absorber 35a, the heat generated by the amplifier 2211 is absorbed and the amplifier 2211 is cooled.
The control valves 35b are disposed at both ends of the heat absorber 35a. The flow of the refrigerant flowing into the heat absorber 35a is controlled by opening and closing the control valve 35b. The control valve 35b is, for example, an electromagnetic valve or an electric valve.
The refrigerant cooling unit 35c is connected to both ends of the heat absorber 35a, cools the refrigerant warmed by absorbing heat from the amplifier 2211, and causes the cooled refrigerant to flow into the heat absorber 35a again.

In this embodiment, for example, when it is desired to cool the amplifier 2211a, the control valve 35b1 is opened, and the control valve 35b2 and the control valve 35b3 are closed. Then, the refrigerant flows only into the heat absorber 35a1, and does not flow into the heat absorber 35a2 and the heat absorber 35a3.
When it is desired to cool the amplifier 2211a and the amplifier 2211b, the control valve 35b1 and the control valve 35b2 are opened, and the control valve 35b3 is closed. Then, the refrigerant flows into the heat absorber 35a1 and the heat absorber 35a2, and does not flow into the heat absorber 35a3.
When it is desired to cool the amplifier 2211a and the amplifier 2211b, the control valve 35b1 is opened and the control valve 35b2 and the control valve 35b3 are closed. Then, the refrigerant flows only into the heat absorber 35a1, and does not flow into the heat absorber 35a2 and the heat absorber 35a3.

Next, the refrigerant cooling unit 35c will be described.
FIG. 8 is a configuration diagram showing the configuration of the refrigerant cooling unit in one embodiment according to the present invention. The refrigerant flows through the heat radiating portion 35c2 and the compressor 35c3 in the direction indicated by the arrow.

  As shown in FIG. 8, the refrigerant cooling unit 35c includes a housing 35c1, a heat radiating unit 35c2, a compressor 35c3, and a propeller fan 35c4.

The housing | casing 35c1 is a container which stores the component apparatus of the refrigerant | coolant cooling part 35c.
The heat radiating portion 35c2 cools the refrigerant by flowing the refrigerant into the inside and cooling the outer surface of the heat radiating portion 35c2 with a propeller fan 35c4, which will be described later, to remove heat from the refrigerant warmed by the amplifier 2211 flowing inside. .
The compressor 35 c 3 compresses the refrigerant flowing in the heat radiating unit 35 c 2 and circulates the refrigerant in the cooling unit 35.
The propeller fan 35c4 supplies air from the outside of the housing 35c1 in order to cool the heat radiating part 35c2 warmed by the warmed refrigerant.
And the thermal radiation part 35c2 and the compressor 35c3 are connected, for example, water is enclosed as a refrigerant | coolant inside. The refrigerant cooled by the heat radiating part 35c2 flows into the heat absorber 35a by the compressor 35c3.

(Operation)
Hereinafter, an operation when imaging the subject 40 using the magnetic resonance imaging apparatus 1 of the present embodiment will be described.

FIG. 9 is a flowchart showing an operation when imaging a subject in one embodiment of the present invention.
The parts other than the switching of the control valve in the cooling unit which is Step ST1055 in the operation flow and the cooling of the RF power amplifier by the cooling unit which is Step ST1056 are the same as those in the first embodiment. Therefore, description is abbreviate | omitted about the location which overlaps.

  As shown in FIG. 9, the control valve 35b in the cooling unit 35 is switched (ST1055).

  Here, in step ST1050, the switch 2212 is switched to open only the control valves 35b at both ends of the heat absorber 35a corresponding to the amplifier 2211 used for power amplification, and the other control valves 35b are closed.

  Specifically, for example, in the case of the cooling unit 35 shown in FIG. 7, for example, when the RF signal is amplified using only the amplifier 2211a, only the control valve 35b1 is opened, and the control valve 35b2 and the control valve 35b3 are used. The control unit 30 outputs a control signal for closing the control valve 35b to each control valve 35b. When the amplifier 2211a and the amplifier 2211b are used to amplify the RF signal, the control unit 30 sends a control signal for opening the control valve 35b1 and the control valve 35b2 and closing the control valve 35b3 to each switch 2212. Output. When the amplifier 2211a, the amplifier 2211b, and the amplifier 2211c are used to amplify the RF signal, the control unit 30 outputs a control signal for opening the control valve 35b1, the control valve 35b2, and the control valve 35b3. Output to. As described above, the control unit 30 controls the opening and closing of the control valve 35b based on the amplifier 2211 used for power amplification.

  As shown in FIG. 9, the RF power amplifier is cooled (ST1056).

  Here, the amplifier 2211 used for power amplification is cooled by the cooling unit 35 that controls the opening and closing of the control valve 35b in step ST1055.

Specifically, for example, when the power is amplified only by the amplifier 2211a, it is only necessary to cool the amplifier 2211a, only the control valve 35b1 is opened, and the control valve 35b2 and the control valve 35b3 are closed to absorb heat. The refrigerant is allowed to flow only in the vessel 35a1, and only the amplifier 2211a is cooled. In this case, since the number of heat absorbers 35a used for cooling is smaller than in the conventional method of cooling using all of the heat absorbers 35a, the pressure of the refrigerant flowing in the heat absorbers 35a increases, Since the flow rate of the flowing refrigerant is increased, the cooling efficiency is increased.
Further, when the amplifier 2211a and the amplifier 2211b amplify the power, the amplifier 2211a and the amplifier 2211b may be cooled, the control valve 35b1 and the control valve 35b2 are opened, the control valve 35b3 is closed, and the heat absorption is performed. The refrigerant is caused to flow through the condenser 35a1 and the heat absorber 35a2, and the amplifier 2211a and the amplifier 2211b are cooled. When the amplifier 2211a, the amplifier 2211b, and the amplifier 2211c amplify power, the control valve 35b1, the control valve 35b2, and the control valve 35b3 are opened, and the heat absorber 35a1, the heat absorber 35a2, and the heat absorber 35a3 are opened. A refrigerant is flowed to cool the amplifier 2211a, the amplifier 2211b, and the amplifier 2211c.

  As described above, in the second embodiment of the present invention, only the control valves 35b at both ends of the heat absorber 35a corresponding to the amplifier 2211 used for power amplification are opened, and the refrigerant is placed only in the heat absorber 35a. Shed. Then, the amplifier 2211 used for power amplification is cooled.

  Thus, by cooling the RF power amplifier 221 only by the heat absorber 35a corresponding to the amplifier 2211 used to amplify the power, the heat generation of the RF power amplifier 221 can be efficiently suppressed, and the RF power The cooling efficiency for the amplifier 221 can be increased. Therefore, a stable operation of the amplifier can be obtained and a desired amplification factor can be obtained. In addition, since a stable operation of the amplifier is obtained, a stable RF pulse can be irradiated in the magnetic resonance imaging apparatus.

  Note that the RF power amplifier 221 in the present embodiment corresponds to the power amplification unit of the present invention. The switch 2212 in the present embodiment corresponds to the amplifier switching unit of the present invention. The heat absorber 35a in the present embodiment corresponds to the amplifier cooling unit or the heat absorber of the present invention. Further, the control valve 35b in the above-described embodiment corresponds to the selection unit or the control valve of the present invention.

  In implementing the present invention, the present invention is not limited to the above-described embodiment, and various modifications can be employed.

In the embodiment of the present invention, the magnitude of the RF pulse is determined based on the imaging region in the subject. However, the present invention is not limited to this. For example, the magnitude of the RF pulse is determined based on the weight of the subject. You may decide.
In the second embodiment of the present invention, the RF power amplifier is cooled by a water cooling method, but the present invention is not limited to this, and the RF power amplifier may be cooled by an air cooling method using a fan or the like. In the case of the air cooling method, a plurality of fans are arranged so that each of the plurality of amplifiers can be cooled, and the fans are activated so as to cool only the fans used for power amplification.
In the embodiment of the present invention, three amplifiers are included in the RF power amplifier. However, the present invention is not limited to this, and a plurality of amplifiers may be used.
In the embodiment of the present invention, the number of switches constituting the RF power amplifier is three. However, the present invention is not limited to this.

FIG. 1 is a configuration diagram showing a configuration of a magnetic resonance imaging apparatus according to an embodiment of the present invention. FIG. 2 is a block diagram showing the configuration of the RF drive unit in one embodiment according to the present invention. FIG. 3 is a block diagram showing the configuration of the RF power amplifier according to one embodiment of the present invention. FIG. 4 is a block diagram showing a configuration of a control unit in one embodiment according to the present invention. FIG. 5 is a flowchart showing scan parameter setting and scanning operations in an embodiment according to the present invention. FIG. 6 is a block diagram showing the configuration of the magnetic resonance imaging apparatus according to one embodiment of the present invention. FIG. 7 is a configuration diagram showing the configuration of the cooling section in one embodiment according to the present invention. FIG. 8 is a configuration diagram showing the configuration of the refrigerant cooling unit in one embodiment according to the present invention. FIG. 9 is a flowchart showing an operation when imaging a subject in one embodiment of the present invention.

Explanation of symbols

1: Magnetic resonance imaging apparatus 2: Scanning unit 3: Operation console unit 11: Static magnetic field space 12: Static magnetic field magnet unit 13: Gradient coil unit 14: RF coil unit 15: Cradle 22: RF drive unit 23: Gradient drive unit 24 : Data collection unit 30: Control unit 31: Storage unit 32: Operation unit 33: Data processing unit 34: Display unit 35: Cooling unit 35a, 35a1, 35a2, 35a3: Heat absorbers 35b, 35b1, 35b2, 35b3: Control valve 35c : Refrigerant cooling part 35c1: Housing 35c2: Heat exchange part 35c3: Compressor 35c4: Propeller fan 40: Subject 221: RF power amplifiers 2211, 2111, 2211b, 2211c: Amplifiers 2212, 2212a, 2 12b, 2212c: Switch 331: power amplification factor calculator

Claims (13)

Based on a magnetic resonance signal generated in the imaging region of the subject by irradiating the imaging region of the subject in the static magnetic field space with an RF pulse by amplifying the power input to the power amplifier and outputting it to the RF coil. A magnetic resonance imaging apparatus for generating a magnetic resonance image in the imaging region of the subject,
The power amplifying unit is connected between the plurality of amplifiers that amplify the power and the amplifiers that switch the combination of the amplifiers according to an amplification factor that amplifies the input power. A switching unit, amplifies the input power based on the amplification factor, and outputs to the RF coil,
A cooling unit for cooling the power amplification unit;
The cooling unit cools only the amplifier used to amplify the power by switching between a plurality of amplifier cooling units that cool each of the plurality of amplifiers and the amplifier switching unit. A magnetic resonance imaging apparatus that cools an amplifier used to amplify the power by the amplifier cooling unit selected by the selection unit. A power amplification factor calculation unit that calculates an amplification factor for amplifying the input power based on the imaging region in the subject;
The amplification factor is calculated by the power amplification factor calculator.
The magnetic resonance imaging apparatus according to claim 1. The amplifier switching unit is connected between all of the plurality of adjacent amplifiers.
The magnetic resonance imaging apparatus according to claim 1 or 2. The magnetic resonance imaging apparatus according to claim 1, wherein the amplifier switching unit is a switch. The amplifier cooling unit is a heat absorber that is arranged around each of the plurality of amplifiers and absorbs heat from the amplifier by flowing a refrigerant therein.
The selection unit is a control valve that controls the flow of the refrigerant so that the refrigerant flows only in the heat absorber that cools the amplifier used to amplify the power.
The magnetic resonance imaging apparatus according to claim 1. The amplifier cooler is disposed in contact with each of the plurality of amplifiers.
The magnetic resonance imaging apparatus according to claim 5. Water is used as the refrigerant,
The magnetic resonance imaging apparatus according to claim 5 or 6. The amplifier cooler is a fan.
The magnetic resonance imaging apparatus according to claim 1. A magnetic resonance imaging apparatus that irradiates an imaging region of a subject in a static magnetic field space with an RF pulse and generates a magnetic resonance image in the imaging region of the subject based on a magnetic resonance signal generated in the imaging region of the subject The RF power amplifying device for amplifying the input power and outputting the amplified power to the RF coil,
A plurality of amplifiers that amplify the input power and an amplifier switching unit that is connected between the plurality of amplifiers and switches the combination of the amplifiers according to an amplification factor that amplifies the input power. And amplifying the input power based on the amplification factor, and outputting to the RF coil,
A cooling unit for cooling the RF power amplification device;
The cooling unit cools only the amplifier used to amplify the power by switching between a plurality of amplifier cooling units that cool each of the plurality of amplifiers and the amplifier switching unit. An RF power amplifying apparatus that cools an amplifier used for amplifying the power by the amplifier cooling unit selected by the selection unit. The amplification factor is calculated based on the imaging region in the subject.
The RF power amplifying device according to claim 9. The amplifier switching unit is connected between all of the plurality of adjacent amplifiers.
The RF power amplification device according to claim 9 or 10. The amplifier switching unit is a switch.
The RF power amplification device according to any one of claims 9 to 11. The amplifier cooling unit is a heat absorber that is arranged around each of the plurality of amplifiers and absorbs heat from the amplifier by flowing a refrigerant therein.
The selection unit is a control valve that controls the flow of the refrigerant so that the refrigerant flows only in the heat absorber that cools the amplifier used to amplify the power.
The magnetic resonance imaging apparatus according to claim 9.

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