JP7286338B2 - High frequency amplification device and magnetic resonance imaging device - Google Patents

Description

TECHNICAL FIELD Embodiments of the present invention relate to radio frequency amplification devices and magnetic resonance imaging devices.

Generally, a magnetic resonance imaging apparatus has an amplifier that amplifies RF signals. An amplifier may use an amplifying element such as an FET (Field Effect Transistor).

Moreover, such an amplifying element has a risk of being damaged when an excessive load is applied.

JP 2017-158883 A JP-A-1-185253

A problem to be solved by the present invention is to reduce excessive load on an amplifying element included in an amplifier.

A high-frequency amplifier device according to an embodiment includes an amplifier and a controller. An amplifier amplifies an input signal and outputs an amplified signal. Based on the input signal, the control unit obtains temperature information regarding the junction temperature of one or more amplifying elements included in the amplifier, and controls the amplifier according to the temperature information.

1 is a block diagram illustrating an example of the configuration of a magnetic resonance imaging apparatus according to an embodiment; FIG. FIG. 2 is a block diagram showing an example of the configuration of the high-frequency amplifier according to the embodiment; 3 is a block diagram illustrating an example of a configuration of a junction temperature calculation circuit according to the embodiment; FIG. FIG. 4 is a flowchart illustrating an example of the flow of determination processing based on junction temperature according to the embodiment; FIG. 5 is a diagram illustrating an example of operation timing of a protection circuit according to a comparative example; FIG. 6 is a diagram illustrating an example of operation timings of the protection circuit according to the embodiment;

Hereinafter, embodiments of a high-frequency amplifier and a magnetic resonance imaging apparatus will be described in detail with reference to the drawings. It should be noted that the high-frequency amplifying device and the magnetic resonance imaging device according to the present application are not limited to the embodiments shown below.

(embodiment)
FIG. 1 is a block diagram showing an example of the configuration of a magnetic resonance imaging (MRI) apparatus 100 according to this embodiment. As shown in FIG. 1, the magnetic resonance imaging apparatus 100 includes a static magnetic field magnet 101, a gradient magnetic field coil 102, a gradient magnetic field power supply 103, a bed 104, a bed control circuit 105, a transmission coil 106, and a transmission circuit 107. , a receiving coil 108 , a receiving circuit 109 , a sequence control circuit 110 , a computer system 120 and a high frequency amplifier 1 . Note that the magnetic resonance imaging apparatus 100 does not include the subject P (eg, human body).

The static magnetic field magnet 101 is a magnet formed in a hollow cylindrical shape (including one having an elliptical cross section orthogonal to the axis of the cylinder), and generates a uniform static magnetic field in the internal space.

The gradient magnetic field coil 102 is a coil formed in a hollow cylindrical shape (including one having an elliptical cross section perpendicular to the axis of the cylinder), and generates a gradient magnetic field.

A gradient magnetic field power supply 103 supplies current to the gradient magnetic field coil 102 .

The bed 104 has a tabletop 104a on which the subject P is placed. Under the control of the bed control circuit 105, the tabletop 104a is moved into the cavity ( (imaging opening). The bed control circuit 105 is a processor that drives the bed 104 and moves the top board 104a in the longitudinal direction and the vertical direction under the control of the computer system 120 .

The transmission coil 106 outputs high frequency to the subject P. FIG. Specifically, the transmission coil 106 is arranged inside the gradient magnetic field coil 102, receives supply of RF (Radio Frequency, high frequency) pulses from the transmission circuit 107, and generates a high frequency magnetic field.

The transmission circuit 107 supplies the transmission coil 106 with an RF pulse corresponding to the Larmor frequency determined by the type of nucleus of interest and the strength of the magnetic field.

The receiving coil 108 is arranged inside the gradient magnetic field coil 102 and receives magnetic resonance signals (hereinafter referred to as MR signals) emitted from the subject P under the influence of the high-frequency magnetic field. Upon receiving the MR signal, the receiving coil 108 outputs the received MR signal to the receiving circuit 109 . Note that in FIG. 1, the receiving coil 108 is provided separately from the transmitting coil 106, but this is an example and the present invention is not limited to this configuration. For example, a configuration in which the receiving coil 108 is also used as the transmitting coil 106 may be adopted.

The receiving circuit 109 performs analog/digital conversion on the analog MR signal output from the receiving coil 108 to generate MR data. The receiving circuit 109 also transmits the generated MR data to the sequence control circuit 110 . Note that analog-to-digital conversion may be performed within the receiving coil 108, and the receiving circuit 109 can perform arbitrary signal processing other than analog-to-digital conversion.

The sequence control circuit 110 images the subject P by controlling the high frequency amplifier 1 , the gradient magnetic field power supply 103 , the transmission circuit 107 and the reception circuit 109 based on the sequence information transmitted from the computer system 120 . The sequence control circuit 110 may be implemented by a processor, or by a mixture of software and hardware.

Sequence information is information defining a pulse sequence executed in an examination by the magnetic resonance imaging apparatus 100 . The sequence information includes the strength of the current supplied by the gradient magnetic field power supply 103 to the gradient magnetic field coil 102 and the timing of supplying the current, the strength of the RF pulse transmitted by the transmission circuit 107 to the transmission coil 106, the timing of applying the RF pulse, and the reception The timing and the like for the circuit 109 to detect the MR signal are defined.

Further, the sequence information includes imaging conditions specified by the operator, such as TR (repetition time), TE (echo time), number of slices, slice thickness, FOV (field of view). , etc., is generated by the computer system 120 based on information on a number of imaging parameters.

High-frequency amplifier 1 is connected to computer system 120 , sequence control circuit 110 , transmission circuit 107 , etc., and generates RF signals based on commands received from computer system 120 or sequence information received from sequence control circuit 110 . This RF signal is an amplified signal obtained by amplifying the RF input signal input from the sequence control circuit 110 by the high-frequency amplifier 1 . The high frequency amplifier device 1 transmits the generated amplified signal to the transmission circuit 107 . Details of the high-frequency amplifier 1 will be described later.

The computer system 120 performs overall control of the magnetic resonance imaging apparatus 100, data acquisition, image reconstruction, and the like. More specifically, computer system 120 controls sequence control circuit 110 , high-frequency amplifier 1 , and bed control circuit 105 . The computer system 120 has an interface circuit 121 , a memory circuit 122 , a processing circuit 123 , an input interface 124 and a display 125 . The computer system 120 is an example of a control system for the magnetic resonance imaging apparatus 100 in this embodiment.

The interface circuit 121 transmits sequence information to the sequence control circuit 110 and receives MR data from the sequence control circuit 110 . Further, upon receiving the MR data, the interface circuit 121 stores the received MR data in the storage circuit 122 .

The storage circuit 122 stores various programs. The storage circuit 122 is implemented by, for example, a RAM (Random Access Memory), a semiconductor memory device such as a flash memory, a hard disk, an optical disk, or the like. Note that the storage circuit 122 is also used as a non-transitory hardware storage medium.

The input interface 124 receives various instructions and information inputs from operators such as doctors and radiological technologists. The input interface 124 is implemented by, for example, a trackball, switch buttons, mouse, keyboard, and the like. The input interface 124 is connected to the processing circuit 123 , converts an input operation received from the operator into an electric signal, and outputs the electric signal to the processing circuit 123 .

The display 125 displays various GUIs (Graphical User Interfaces), MR (Magnetic Resonance) images, etc. under the control of the processing circuit 123 .

The processing circuit 123 performs overall control of the magnetic resonance imaging apparatus 100 . Specifically, the processing circuit 123 controls imaging by generating sequence information based on the imaging conditions input by the operator via the input interface 124 and transmitting the generated sequence information to the sequence control circuit 110. do. The processing circuit 123 also arranges the MR data sent from the sequence control circuit 110 as a result of imaging according to the phase encoding amount and frequency encoding amount imparted by the gradient magnetic field described above. The arranged MR data is called k-space data, and reconstruction processing such as Fourier transform is performed on the k-space data to generate an MR image. The processing circuit 123 controls display of the generated MR image on the display 125 . The processing circuit 123 is realized by a processor.

The processing circuit 123 executes various programs read from the storage circuit 122 to implement functions corresponding to each program. Note that the processing circuit 123 may be configured by combining a plurality of independent processors.

Next, the details of the high-frequency amplifier device 1 according to the present embodiment will be described. FIG. 2 is a block diagram showing an example of the configuration of the high frequency amplifier 1 according to the embodiment.

As shown in FIG. 2, the high frequency amplifier device 1 includes an amplifier 1d, a junction temperature calculation circuit 1a, a voltage control circuit 1z, a protection circuit 1y, and a coupler 1b.

An input terminal 1e of the high frequency amplifier 1 is connected to an output terminal 110a of the sequence control circuit 110. FIG. The high frequency amplifier 1 acquires an RF input signal (RF IN) from the sequence control circuit 110 via the input terminal 1e. The RF input signal is an example of the input signal in this embodiment.

Also, the output terminal 1 i of the high-frequency amplifier 1 is connected to the input terminal 106 a of the transmission coil 106 via the transmission circuit 107 . The high-frequency amplifier 1 supplies an amplified signal, which is an RF input signal amplified by the amplifier 1 d , to the transmission coil 106 via the transmission circuit 107 . The amplified signal is also referred to as the RF output signal (RF OUT).

The amplifier 1d amplifies the RF input signal and outputs an amplified signal while a voltage is applied from the voltage control circuit 1z. The amplifier 1d acquires an RF input signal input from the sequence control circuit 110 via the input terminal 1e of the high frequency amplifier 1 and the junction temperature calculation circuit 1a. The amplifier 1d comprises an amplifier circuit including one or more amplifying elements. The amplifying element is, for example, a transistor such as an FET (Field Effect Transistor). The amplifier 1d is also called an RF amplifier.

The junction temperature calculation circuit 1a obtains temperature information regarding the junction temperature of the FET included in the amplifier 1d based on the RF input signal, and controls the amplifier 1d according to the temperature information. The junction temperature calculation circuit 1a is an example of a control section in this embodiment.

In this embodiment, the temperature information is the junction temperature value of the amplifying element.

The junction temperature calculation circuit 1a of this embodiment includes an RF input signal, linearity information of the amplifier 1d, power loss per one or more amplification elements, thermal resistance of the one or more amplification elements, and a reference temperature. , the junction temperature of the amplifying element is calculated. The details of the procedure for calculating the junction temperature will be described later.

Further, the junction temperature calculation circuit 1a of the present embodiment stops outputting the amplified signal according to the calculated junction temperature. Specifically, the junction temperature calculation circuit 1a stops outputting the amplified signal when the calculated junction temperature is equal to or higher than a predetermined threshold. As an example, when the junction temperature calculated based on the RF input signal is equal to or higher than a predetermined threshold, the junction temperature calculation circuit 1a transmits a stop signal indicating an instruction to stop the amplifier 1d to the protection circuit 1y. Stops the output of the amplified signal.

The predetermined threshold is, for example, the upper limit of the temperature at which the amplifying element can operate normally. If the junction temperature of the FET exceeds a predetermined threshold, there is a risk of damage to the FET.

The coupler 1b outputs the amplified signal output from the amplifier 1d to the output terminal 1i, and outputs a signal corresponding to the amplified signal to the voltage control circuit 1z for feedback. For example, the coupler 1b outputs a signal proportional to the amplified signal to the voltage control circuit 1z. The output destination of the coupler 1b is an example, and is not limited to this.

The protection circuit 1y is a circuit that stops the amplifier 1d under a predetermined condition in order to avoid damage to an amplifying element such as an FET included in the amplifier 1d. The protection circuit 1y of the present embodiment stops the amplifier 1d when receiving a stop signal representing an instruction to stop the amplifier 1d from the junction temperature calculation circuit 1a.

The voltage control circuit 1z is a circuit for changing the power supply voltage used by the amplifier 1d for amplifying the input signal according to the magnitude of the RF input signal. The voltage control circuit 1z acquires information including the application timing and waveform information of the high-frequency magnetic field from the sequence control circuit 110, and changes the magnitude of the power supply voltage supplied to the amplifier 1d based on the information. Also, the voltage control circuit 1z may adjust the power supply voltage based on the amplified signal fed back from the coupler 1b.

Next, details of the junction temperature calculation circuit 1a will be described. FIG. 3 is a block diagram showing an example of the configuration of the junction temperature calculation circuit 1a according to this embodiment. As shown in FIG. 3, the junction temperature calculation circuit 1a includes an RF output power calculation circuit 10a, an internal loss calculation circuit 10b, a temperature calculation circuit 10c, and a determination circuit 10d.

The RF output power calculation circuit 10 a detects the RF input signal input from the sequence control circuit 110 . Further, the RF output power calculation circuit 10a calculates the RF output power output from the amplifier 1d based on the detected RF input signal and the linearity information of the amplifier circuit of the amplifier 1d.

The linearity information is information that specifies the gain with which the amplifier circuit amplifies the input signal, and is predetermined depending on the amplifier circuit. The linearity information is an example of amplification information regarding the degree of amplification of the amplifier 1d in this embodiment.

The RF output power calculation circuit 10a sends the calculated RF output power to the internal loss calculation circuit 10b.

Based on the RF output power calculated by the RF output power calculation circuit 10a, the power efficiency of the amplifier circuit, and the number of amplification elements included in the amplifier 1d, the internal loss calculation circuit 10b calculates Calculate the internal loss of The power efficiency of an amplifier circuit depends on the FETs used in the amplifier circuit and the power level of the RF output power (RF output level). For example, it is assumed that the value of the power efficiency of the amplifier circuit is previously associated with each RF output level. The internal loss calculation circuit 10b sends the calculated internal loss to the temperature calculation circuit 10c.

The temperature calculating circuit 10c calculates the junction temperature of the amplifying element based on the internal loss per amplifying element calculated by the internal loss calculating circuit 10b, the thermal resistance of each amplifying element, and the reference temperature. . The thermal resistance of the individual amplifying elements is, for example, a predetermined thermal resistance depending on the FETs used as amplifying elements. As an example, the thermal resistance of an individual gain element is the sum of the thermal resistance between the package and the die of the individual gain element and the thermal resistance from the package to the surroundings of the package. Here, it is assumed that heat dissipation by a heat sink or the like included in the amplifier circuit is added in advance to the thermal resistance of each amplifier element.

Also, the reference temperature is the junction temperature of the amplifying element when the temperature is not increased due to the amplification process of the RF input signal.

For example, if the amplifier circuit is provided with a water-cooled cooling device, the reference temperature remains unchanged. In this case, the temperature calculation circuit 10c may store the reference temperature as the predetermined temperature in advance.

Further, when the amplifier circuit includes an air-cooled cooling device, the reference temperature changes depending on the ambient temperature of the amplifier circuit. In this case, the temperature calculation circuit 10c may use the ambient temperature obtained from the temperature sensor installed in the amplifier 1d as the reference temperature. Alternatively, the temperature calculation circuit 10c may calculate the reference temperature based on the execution time of the amplification process of the amplifier 1d, etc., even in the case of an air-cooled type. For example, when the amplifier 1d is not performing amplification processing, the junction temperature of the amplifier circuit decreases. The temperature in the state where the

The temperature calculation circuit 10c multiplies the calculated thermal resistance of the amplifier element by the internal loss per amplifier element calculated by the internal loss calculation circuit 10b to obtain the amount of increase in the junction temperature of the amplifier element, i.e., the increase Calculate the temperature in minutes. Further, the temperature calculation circuit 10c calculates the junction temperature by adding the reference temperature to the amount of increase in the junction temperature of the amplifying element.

Further, when heat radiation by a heat sink or the like is not taken into account in the predetermined thermal resistance of each amplifying element, the temperature calculation circuit 10c calculates the heat radiation amount of the heat sink included in the amplifier circuit, the FETs included in the amplifier circuit, and the The cooling capacity of the cooling system provided in the amplifier circuit may be calculated from the heat capacities of other parts. In this case, the temperature calculation circuit 10c calculates the actual junction temperature considering the cooling system by taking into account the increase in the junction temperature without considering the cooling system and the decrease in temperature due to the cooling system provided in the amplifier circuit. Also good. The temperature calculation circuit 10c sends the calculated junction temperature to the determination circuit 10d.

The determination circuit 10d determines whether the calculated junction temperature is equal to or higher than a predetermined threshold. The determination circuit 10d transmits a stop signal to the protection circuit 1y when determining that the junction temperature is equal to or higher than a predetermined threshold. Further, when the determination circuit 10d determines that the junction temperature is less than the predetermined threshold value, the input of the RF input signal to the amplifier 1d is continued.

Also, the method for calculating the junction temperature is not limited to this. For example, the junction temperature calculation circuit 1a calculates the current flowing through the amplifying element based on the RF output power calculated based on the RF input signal and the linearity information and the internal loss per amplifying element, A voltage to be applied to the amplifying element is obtained from the calculated current. Here, it is assumed that the junction temperature calculation circuit 1a stores in advance the correspondence relationship between the voltage applied to the amplifying element and the amount of increase in the junction temperature of the amplifying element. Then, the junction temperature calculation circuit 1a may calculate the increase amount of the junction temperature based on the calculated voltage.

Each configuration of the junction temperature calculation circuit 1a is not limited to a hardware circuit, and may be implemented by a processor or by a mixture of software and hardware.

For example, the junction temperature calculation circuit 1a may have an RF output power calculation function, an internal loss calculation function, a temperature calculation function, and a determination function as functions implemented by a processor. For example, these functions may be stored in the storage circuit within the junction temperature calculation circuit 1a in the form of a computer-executable program. The junction temperature calculation circuit 1a reads each program from the storage circuit and executes each read program, thereby realizing a function corresponding to each program. In other words, the junction temperature calculation circuit 1a with each program read has each function shown in the junction temperature calculation circuit 1a of FIG. The functions of the junction temperature calculation circuit 1a may be realized by a processor, or may be realized by combining a plurality of independent processors and executing each program by each processor.

The term "processor" used in the above description is, for example, a CPU (central preprocess unit), a GPU (Graphics Processing Unit), or an application specific integrated circuit (ASIC), a programmable logic device (e.g., Circuits such as Simple Programmable Logic Device (SPLD), Complex Programmable Logic Device (CPLD), and Field Programmable Gate Array (FPGA)). Instead of storing the program in the memory circuit, the program may be directly incorporated in the circuit of the processor. In this case, the processor realizes its function by reading and executing the program embedded in the circuit.

Here, the program executed by the processor is stored in a computer-readable storage medium such as CD (Compact Disk)-ROM, FD (Flexible Disk), CD-R (Recordable), DVD (Digital Versatile Disk). may be provided. Also, this program may be stored on a computer connected to a network such as the Internet, and may be provided or distributed by being downloaded via the network.

Next, the flow of determination processing based on the junction temperature according to this embodiment will be described. FIG. 4 is a flow chart showing an example of the flow of judgment processing based on the junction temperature according to this embodiment.

First, the RF output power calculation circuit 10a of the junction temperature calculation circuit 1a detects an RF input signal input from the sequence control circuit 110 (S1).

Then, the RF output power calculation circuit 10a calculates the RF output power output from the amplifier 1d based on the RF input signal input from the sequence control circuit 110 and the linearity information of the amplifier circuit of the amplifier 1d. (S2).

Then, the internal loss calculation circuit 10b calculates the amplification element An internal loss per piece is calculated (S3).

Next, the temperature calculating circuit 10c calculates the junction temperature of the amplifying element based on the internal loss per amplifying element calculated by the internal loss calculating circuit 10b, the thermal resistance of each amplifying element, and the reference temperature. is calculated (S4).

Then, the determination circuit 10d determines whether or not the calculated junction temperature is equal to or higher than a predetermined threshold (S5).

When the determination circuit 10d determines that the junction temperature is equal to or higher than the predetermined threshold ("Yes" in S5), the determination circuit 10d transmits a stop signal to the protection circuit 1y to stop the amplifier 1d, thereby stopping the output of the amplified signal. (S6).

Further, when the determination circuit 10d determines that the junction temperature is less than the predetermined threshold value (S5 "No"), the input of the RF input signal to the amplifier 1d is continued. In this case, the amplifier 1d outputs an amplified signal obtained by amplifying the RF input signal. Here, the processing of this flowchart ends.

As described above, the high-frequency amplifier device 1 of the present embodiment obtains temperature information regarding the junction temperature of one or more amplifying elements included in the amplifier 1d based on the RF input signal, and controls the amplifier 1d according to the temperature information. . Since the high-frequency amplifier 1 of this embodiment controls the amplifier 1d based on the junction temperature calculated from the RF input signal, the amplifier 1d is controlled before the junction temperature of the amplifying element actually rises. That is, according to the high-frequency amplifier device 1 of the present embodiment, it is possible to prevent the junction temperature of the amplifying element from actually rising. Therefore, according to the high-frequency amplifying device 1 of the present embodiment, it is possible to reduce the excessive load applied to the amplifying element due to the excessive output. As a result, for example, the high-frequency amplifier device 1 of the present embodiment can reduce damage to the amplification elements included in the amplifier 1d.

Here, the effect of the high-frequency amplifier 1 of this embodiment will be described in more detail by comparison with a comparative example.

FIG. 5 is a diagram illustrating an example of operation timing of a protection circuit according to a comparative example; In the comparative example, the average value per unit time of the RF output power output from the amplifier circuit was calculated. In the comparative example, the protection circuit operates to stop the amplifier when the average value of the average power of the RF output power per unit time is greater than or equal to the threshold value.

However, in this comparative example, since the operation timing of the protection circuit is determined based on the RF output power, the FET has already been overloaded when the protection circuit operates. Further, in the comparative example, since the average RF output power per unit time is calculated, even if the RF output power exceeds the threshold within the unit time, the determination is made after the unit time has elapsed. Therefore, in the comparative example, when excessive power is momentarily applied to the FET, the protection circuit may operate after the FET is damaged.

In contrast, the high-frequency amplifier 1 of this embodiment controls the amplifier 1d based on the junction temperature calculated from the RF input signal. More specifically, the high-frequency amplifier 1 of the present embodiment stops the output of the amplified signal according to the calculated junction temperature. can be made

FIG. 6 is a diagram showing an example of operation timings of the protection circuit according to this embodiment. As shown in FIG. 6, in this embodiment, the protection circuit 1y operates when the junction temperature of the amplifying element reaches the threshold. Therefore, according to the high-frequency amplifier device 1 of the present embodiment, damage to the FETs can be reduced.

(Modification 1)
In the above-described embodiment, the temperature information is the value of the junction temperature of the amplifying element, but the temperature information is not limited to this. In this modification, the temperature information is the amount of increase in junction temperature.

In this modification, the junction temperature calculation circuit 1a is based on the RF input signal, the linearity information of the amplifier 1d, the power loss per one of the one or more amplification elements, and the thermal resistance of the one or more amplification elements. to calculate the amount of increase in the junction temperature of the amplifying element. When the junction temperature calculation circuit 1a determines that the amount of increase in junction temperature is equal to or greater than a predetermined threshold, the junction temperature calculation circuit 1a stops outputting the amplified signal by transmitting a stop signal to the protection circuit 1y.

(Modification 2)
Further, in the above-described embodiment, the junction temperature calculation circuit 1a sends a stop signal to the protection circuit 1y to stop the output of the amplified signal when it determines that the junction temperature is equal to or higher than the predetermined threshold. However, the processing when the junction temperature is equal to or higher than the predetermined threshold is not limited to this.

In this modification, the junction temperature calculation circuit 1a reduces the output of the amplified signal according to the temperature information. For example, when the junction temperature calculation circuit 1a determines that the junction temperature is equal to or higher than a predetermined threshold, the junction temperature calculation circuit 1a notifies the computer system 120 that the junction temperature is equal to or higher than the predetermined threshold, and reduces the output of the amplified signal. Alternatively, the junction temperature calculation circuit 1a may notify the sequence control circuit 110 that the junction temperature is equal to or higher than a predetermined threshold, and reduce the output of the amplified signal.

Further, the RF output power calculation circuit 10a of the present modification may transmit warning information to the computer system 120 to prompt suspension of the amplification signal or reduction in the output of the amplification signal according to the temperature information.

For example, when the junction temperature calculation circuit 1a of this modification determines that the junction temperature is equal to or higher than a predetermined threshold value, the computer system 120 instructs the computer system 120 to change the imaging condition, for example, to a sequence with a lower load by lengthening TR. Send notifications recommending When the computer system 120 receives the notification from the junction temperature calculation circuit 1a, the computer system 120 displays a warning or a message recommending a change in imaging conditions on the display 125. FIG.

When an operator who visually recognizes the warning or message performs an operation to change the imaging conditions, the computer system 120 changes the sequence information based on the changed imaging conditions, and sends the changed sequence information to the sequence control circuit. output to 110. Then, the sequence control circuit 110 reduces the load on the amplifying element by controlling the high-frequency amplifying device 1 based on the changed sequence information.

Further, the computer system 120 may estimate an imaging condition under which the junction temperature is less than a predetermined threshold based on feedback from the junction temperature calculation circuit 1a instead of prompting the operator to change the imaging condition.

According to the high-frequency amplifying device 1 of this modified example, it is possible to reduce excessive load on the amplifying element included in the amplifier 1d or breakage of the amplifying element while continuing imaging.

Further, according to the magnetic resonance imaging apparatus of this modified example, by warning the operator according to the temperature information, the operator can be given an opportunity to respond before the protection circuit 1y operates. Therefore, according to the magnetic resonance imaging apparatus of this modified example, it is possible to avoid situations such as forced stop of imaging or breakage of the amplifying element.

(Modification 3)
Further, in the above-described embodiment, the RF output power calculation circuit 10a of the junction temperature calculation circuit 1a detects the RF input signal input from the sequence control circuit 110, but does not acquire control information regarding the RF input signal. can be For example, the RF output power calculation circuit 10 a of the present modification acquires control information regarding the RF input signal from the computer system 120 or the sequence control circuit 110 . Then, the RF output power calculation circuit 10a of this modified example calculates the RF output power output from the amplifier 1d based on the control information and the linearity information.

Although the computer system 120 is used as an example of the control system in the above embodiment, the sequence control circuit 110 may be used as an example of the control system.

(Modification 4)
Also, in the above-described embodiment, the junction temperature calculation circuit 1a calculates the junction temperature based on the RF input signal, but the method of obtaining the junction temperature is not limited to this. For example, the junction temperature calculation circuit 1a of this modification may specify the amount of increase in junction temperature based on a lookup table in which the RF input signal and the amount of increase in junction temperature are associated with each other. good. A lookup table is an example of temperature identification information.

According to the high-frequency amplifying device 1 of the present modification, the amount of increase in junction temperature can be calculated without executing the processing for calculating the amount of increase in junction temperature each time an RF input signal is input, so the processing speed can be reduced. can be improved.

(Modification 5)
In the above-described embodiment, the junction temperature calculation circuit 1a stops the output of the amplified signal by sending a stop signal to the protection circuit 1y. , the output of the amplified signal may be stopped.

According to at least one embodiment described above, it is possible to reduce excessive load on the amplifying element included in the amplifier 1d.

While several embodiments of the invention have been described, these embodiments have been presented by way of example and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, replacements, and modifications can be made without departing from the scope of the invention. These embodiments and their modifications are included in the scope and spirit of the invention, as well as the scope of the invention described in the claims and equivalents thereof.

1b Coupler 1a Junction temperature calculation circuit 1 High frequency amplifier 1d Amplifier 1y Protection circuit 10a RF output power calculation circuit 10b Internal loss calculation circuit 10c Temperature calculation circuit 10d Judgment circuit 100 Magnetic resonance imaging apparatus 102 Gradient magnetic field coil 103 Gradient magnetic field power supply 106 Transmitting coil 107 Transmitting circuit 108 Receiving coil 109 Receiving circuit 110 Sequence control circuit 120 Computer system

Claims (8)

an amplifier that amplifies an input signal and outputs an amplified signal;
a protection circuit that deactivates the amplifier or regulates the output of the amplifier ;
a control unit that calculates temperature information about a junction temperature of one or more amplification elements included in the amplifier based on the input signal, and controls the amplifier according to the temperature information;
with
The temperature information is the junction temperature of one or more of the amplifying elements or the amount of increase in the junction temperature;
When the calculated junction temperature or the amount of increase in the junction temperature is equal to or greater than a predetermined first threshold, the control unit controls the junction temperature or the amount of increase in the junction temperature based on the calculated junction temperature or the amount of increase in the junction temperature. estimating the output of the amplifier at which the amount of temperature increase is less than the first threshold;
depending on the estimated output, stop or adjust the output of the amplified signal by transmitting an adjustment signal representing an instruction to the protection circuit to stop the amplifier or adjust the output of the amplifier;
High frequency amplifier. The control unit detects the input signal input to the amplifier,
2. The high frequency amplifier device according to claim 1. The control unit acquires control information about the input signal input to the amplifier from a control system that controls the high-frequency amplifier.
3. The high frequency amplifier device according to claim 1 or 2. Based on the input signal, amplification information about the amplification degree of the amplifier, power loss per one of the one or more amplification elements, and thermal resistance of the one or more amplification elements, the control unit calculating temperature information,
4. The high-frequency amplifier device according to any one of claims 1 to 3. The control unit identifies the temperature information based on temperature identification information in which the input signal and the temperature information are associated.
4. The high-frequency amplifier device according to any one of claims 1 to 3. a transmission coil that outputs a high frequency to an object;
a high-frequency amplifier that supplies an amplified signal to the transmission coil,
The high-frequency amplifier is
an amplifier that amplifies an input signal and outputs an amplified signal;
a protection circuit that deactivates the amplifier or regulates the output of the amplifier ;
a control unit that calculates temperature information about a junction temperature of one or more amplification elements included in the amplifier based on the input signal, and controls the amplifier according to the temperature information;
with
The temperature information is the junction temperature of one or more of the amplifying elements or the amount of increase in the junction temperature;
When the calculated junction temperature or the amount of increase in the junction temperature is equal to or greater than a predetermined first threshold, the control unit controls the junction temperature or the amount of increase in the junction temperature based on the calculated junction temperature or the amount of increase in the junction temperature. estimating the output of the amplifier at which the amount of temperature increase is less than the first threshold;
depending on the estimated output, stop or adjust the output of the amplified signal by transmitting an adjustment signal representing an instruction to the protection circuit to stop the amplifier or adjust the output of the amplifier;
Magnetic resonance imaging equipment. a transmission coil that outputs a high frequency to an object;
a high-frequency amplifier that supplies an amplified signal to the transmission coil;
a sequence control circuit that controls the transmission coil and the high-frequency amplifier to image the subject;
with
The high-frequency amplifier is
an amplifier that amplifies an input signal and outputs an amplified signal;
a control unit that calculates temperature information about a junction temperature of one or more amplification elements included in the amplifier based on the input signal, and controls the amplifier according to the temperature information;
with
The temperature information is the junction temperature of one or more of the amplifying elements or the amount of increase in the junction temperature;
When the calculated junction temperature or the amount of increase in the junction temperature is equal to or greater than a predetermined second threshold, the control unit of the high-frequency amplifier device performs the above-described estimating an imaging condition under which the junction temperature or an increase in the junction temperature is less than the second threshold, and notifying the sequence control circuit of the estimated imaging condition;
The sequence control circuit controls the high-frequency amplification device to reduce the output of the amplified signal in accordance with the notified imaging conditions .
Magnetic resonance imaging equipment. Further comprising a control system for controlling the high-frequency amplifier,
If the calculated junction temperature or the amount of increase in junction temperature is less than the first threshold and is greater than or equal to a third threshold that is lower than the first threshold, Sending warning information prompting a decrease in the output of the amplified signal to the control system;
7. A magnetic resonance imaging apparatus according to claim 6.

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