A switching power supply and magnetic resonance imaging system

Abstract

The present application provides a switching power supply and a magnetic resonance imaging system. The switching power supply is used to power a radio frequency coil control device, the radio frequency coil control device is used to control the flow of radio frequency power output by a radio frequency amplifier of the magnetic resonance imaging system, and the switching power supply includes a first power unit, a second power unit and an air-core transformer, the second power unit is electrically coupled to the first power unit through the air-core transformer, wherein the switching power supply is configured to operate at a preset frequency, and the multiple of the preset frequency is outside the receiving bandwidth of the magnetic resonance imaging system.

Description

Technical Field

[0001] The invention relates to a magnetic resonance imaging system, and in particular to a switching power supply in the magnetic resonance imaging system. Background Art

[0002] Generally, a magnetic resonance imaging system includes a radio frequency coil assembly, a radio frequency amplifier, a radio frequency coil control device, and a switching power supply. The radio frequency coil control device can control the output direction of the radio frequency power output by the radio frequency amplifier to control the selection of a specific type of radio frequency transmitting coil and / or a specific type of radio frequency receiving coil. The switching power supply is connected to the radio frequency coil control device to supply power to the radio frequency coil control device. The switching power supply and the radio frequency coil control device are usually arranged in a scanning room with a strong magnetic field. A transformer is usually arranged in the switching power supply. If the transformer has magnetism, it cannot work in a strong magnetic field environment.

[0003] In addition, although the efficiency of supplying power to the radio frequency coil control device through a switching power supply is high, it will generate relatively large noise and correspondingly generate relatively large electromagnetic interference in the magnetic field, thus affecting the accuracy of the magnetic resonance image. Summary of the invention

[0004] The invention provides a switching power supply and a magnetic resonance imaging system.

[0005] An exemplary embodiment of the present invention provides a switching power supply, which is used to power a radio frequency coil control device, and the radio frequency coil control device is used to control the flow of radio frequency power output by a radio frequency amplifier of a magnetic resonance imaging system, and the switching power supply includes a first power unit, a second power unit and an air-core transformer, and the second power unit is electrically coupled to the first power unit through the air-core transformer, wherein the switching power supply is configured to operate at a preset frequency, and the frequency multiple of the preset frequency is outside the receiving bandwidth of the magnetic resonance imaging system.

[0006] An exemplary embodiment of the present invention further provides a magnetic resonance imaging system, which includes a radio frequency coil assembly, a radio frequency amplifier, a radio frequency coil control device and a switching power supply, wherein the radio frequency coil assembly includes a radio frequency transmitting coil and a radio frequency receiving coil, the radio frequency amplifier is used to output radio frequency power to excite the radio frequency coil assembly to generate a radio frequency signal, the radio frequency coil control device is used to control the output direction of the radio frequency power to control the selection of the type of the radio frequency transmitting coil and / or the type of the radio frequency receiving coil, the switching power supply is connected to the radio frequency coil control device and is configured to supply power to the radio frequency coil control device, and the switching power supply includes a first power unit, a second power unit and an air-core transformer, the second power unit is electrically coupled to the first power unit through the air-core transformer, wherein the switching power supply is configured to operate at a preset frequency, and the multiple of the preset frequency is outside the receiving bandwidth of the magnetic resonance imaging system.

[0007] Other features and aspects will become apparent from the following detailed description, drawings, and claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] The present invention may be better understood by describing exemplary embodiments of the present invention in conjunction with the accompanying drawings, in which:

[0009] Figure 1 is a schematic diagram of a magnetic resonance imaging system according to some embodiments of the present invention;

[0010] Figure 2 is based on Figure 1 A schematic diagram of a radio frequency coil control device of a magnetic resonance imaging system is shown;

[0011] Figure 3 is based on Figure 1 A schematic diagram of a switching power supply in a magnetic resonance imaging system shown; and

[0012] Figure 4 is based on Figure 3 Schematic diagram of the transformer in the switching power supply shown. DETAILED DESCRIPTION

[0013] The specific embodiments of the present invention will be described below. It should be noted that in the specific description of these embodiments, in order to provide a concise description, it is impossible for this specification to provide a detailed description of all the features of the actual embodiments. It should be understood that in the actual implementation of any embodiment, just as in the process of any engineering project or design project, in order to achieve the specific goals of the developer and to meet system-related or business-related restrictions, various specific decisions are often made, and this will also change from one embodiment to another. In addition, it can also be understood that although the efforts made in this development process may be complex and lengthy, for ordinary technicians in the field related to the content disclosed by the present invention, some changes such as design, manufacturing or production based on the technical content disclosed in this disclosure are just conventional technical means, and should not be understood as insufficient content of this disclosure.

[0014] Unless otherwise defined, the technical or scientific terms used in the claims and the specification shall have the usual meaning understood by persons with ordinary skills in the technical field to which the invention belongs. The words "first", "second" and similar words used in the patent application specification and the claims of the present invention do not indicate any order, quantity or importance, but are only used to distinguish different components. "One" or "one" and other similar words do not indicate a quantitative limitation, but indicate the existence of at least one. "Include" or "comprises" and other similar words mean that the elements or objects appearing before "include" or "comprises" include the elements or objects listed after "include" or "comprises" and their equivalent elements, and do not exclude other elements or objects. "Connected" or "connected" and other similar words are not limited to physical or mechanical connections, nor are they limited to direct or indirect connections.

[0015] In some embodiments, in a magnetic resonance imaging system (MRI), a switching power supply may be configured to power a radio frequency coil control device for controlling the flow of radio frequency power output by a radio frequency amplifier, so as to control the selection of a specific type of radio frequency transmitting coil and / or a specific type of radio frequency receiving coil. It should be noted that, from the perspective of a person skilled in the art or related fields, such a description should not be understood as limiting the present invention to powering a radio frequency coil control device or a magnetic resonance imaging system. In fact, the switching power supply described herein may be reasonably applied to other related occasions, such as communications, medical treatment, and welding, etc.

[0016] Figure 1 FIG. 4 is a block diagram of a magnetic resonance imaging system according to an embodiment of the present invention. Figure 1As shown, the magnetic resonance imaging system 10 includes a main magnet 12, a gradient system 13, a radio frequency system 14 and a control system 17. The hollow portion of the main magnet 12 forms a scanning cavity 11, and a carrying bed 15 for carrying a subject 16 (such as a human body) can enter the scanning cavity 11 to perform magnetic resonance imaging on the subject 16. The static magnetic field B generated by the main magnet 12 0 The detected object 16 in the scanning cavity 11 generates a longitudinal macroscopic magnetization vector.

[0017] The gradient system 13 includes gradient coils arranged in different directions (e.g., up and down, left and right, front and back directions of the human body, corresponding to the Z axis, X axis and Y axis of the reconstructed coordinates) and a gradient controller (not shown). The gradient controller is used to emit gradient pulses to the gradient coils to linearly superimpose the gradient field on the static magnetic field to achieve spatial positioning of the magnetic resonance signal, so as to generate a magnetic resonance image of any layer or volume.

[0018] The radio frequency system 14 includes a radio frequency coil assembly 40, a radio frequency amplifier 45, a radio frequency coil control device 43, and a switching power supply 44. The radio frequency coil assembly 40 may include a radio frequency transmitting coil 41 and a radio frequency receiving coil 42, the radio frequency transmitting coil 41 includes a body coil and a head coil, etc., and the radio frequency receiving coil 42 includes a body coil, a head coil, a surface coil, etc.

[0019] The RF amplifier 45 is used to output RF power to excite the RF coil assembly 40 to generate a RF signal. For example, a RF excitation pulse can be transmitted to the RF transmitting coil 41 to excite the longitudinal magnetization vector of the object to be detected to flip, thereby generating a transverse magnetization vector. After the RF excitation pulse ends, the transverse magnetization vector decays spirally around the external magnetic field at a fixed angular frequency to generate a free induction decay signal. The RF receiving coil 42 can generate a magnetic resonance signal for imaging the object to be detected by collecting and analyzing the free induction decay signal.

[0020] The RF coil control device 43 can be used to control the output flow direction of the RF power to control the selection of the specific type of the RF transmitting coil 41 and / or the specific type of the RF receiving coil 42. The switching power supply 44 is connected to the RF coil control device 43 and is configured to supply power to the RF coil control device 43. In some embodiments, the RF coil control device 43 can control the selection of one of the body coil and the head coil as the RF transmitting coil, and the selected coil can also be used as the RF receiving coil. In some embodiments, the RF coil control device 43 can control the selection of one of the body coil and the head coil as the RF transmitting coil, and cannot control the selection of the specific type of the RF receiving coil. In some embodiments, the RF coil control device 43 includes a switch, and when the switch is turned on, the RF power flows to the body coil to control the operation of the body coil, and when the switch is turned off, the RF power flows to the head coil to control the operation of the head coil. In some embodiments, the RF transmitting coil is not limited to the body coil and the head coil mentioned in the present application, and may also include various other suitable coil types. The RF receiving coil is also not limited to the body coil, the head coil and the surface coil mentioned in the present application, and may also include various other suitable coil types.

[0021] On the one hand, the control system 17 is used to generate a pulse control sequence, which is sent to the RF amplifier 45 and the gradient controller via the sequence generator 18, so that the RF amplifier 45 and the gradient controller respectively execute the RF timing and the gradient timing in the pulse control sequence, and collect magnetic resonance signals at a specific time period of the timing. On the other hand, the control system 17 is used to reconstruct an image based on the collected magnetic resonance signals.

[0022] Figure 2 Shows Figure 1 FIG. 4 is a schematic diagram of a radio frequency coil control device 43 in a magnetic resonance imaging system 10. Figure 2 As shown, the RF coil control device 43 includes a control switch 27 , a half-bridge circuit 30 , and a voltage conversion device 50 .

[0023] In some embodiments, the voltage conversion device 50 is configured to receive the first drive signal through the terminal 21 and can convert the first drive signal into a first control signal. In some embodiments, a first end of the voltage conversion device 50 is connected to the switching power supply 44. In some embodiments, the voltage conversion device 50 includes a photocoupler.

[0024] In some embodiments, the RF coil control device 43 further includes a buffer unit 55 , which is configured to receive the second driving signal through the terminal 22 and buffer the second driving signal to generate a second control signal.

[0025] In some embodiments, the half-bridge circuit 30 includes a first switch 31 and a second switch 32 connected in series, a driving end (i.e., a gate) of the first switch 31 is connected to the second end of the voltage conversion device 50 to receive the first control signal, a drain of the first switch 31 is connected to the high voltage power supply 25, a source of the first switch 31 is connected to the drain of the second switch 32 and the third end of the voltage conversion device 50, a driving end (i.e., a gate) of the second switch 32 is connected to the buffer unit 55 to receive the second control signal, and a source of the second switch 32 is connected to the constant current source 26. In some embodiments, the first switch 31 and the second switch 32 can be any suitable solid-state semiconductor switching devices, for example, insulated gate bipolar transistors (IGBTs) and metal oxide semiconductor field effect transistors (MOSFETs).

[0026] In some embodiments, the control switch 27 is connected to the connection point 23 between the first switch 31 and the second switch 32, and is configured to control the output direction of the RF power based on the on and off of the first switch 31 and the second switch 32. In some non-limiting embodiments, the control switch 27 can be a diode. When the first switch 31 is turned on and the second switch 32 is turned off, the control switch 27 is reversely cut off, and no current flows through the control switch 27. When the first switch 31 is turned off and the second switch 32 is turned on, the current will flow through the control switch 27 to the second switch 32 and the current source 26, which is equivalent to the control switch 27 being turned on. In some embodiments, other non-limiting examples of the control switch 27 include a transistor, a gate-commutated thyristor, a field effect transistor, an insulated gate bipolar transistor (IGBT), a gate turn-off thyristor, a static induction transistor, a static induction thyristor, or a combination thereof.

[0027] In some embodiments, the first drive signal and the second drive signal can be controlled to control the on and off of the first switch 31 and the second switch 32. For example, when the first drive signal is at a high level and the second drive signal is at a low level, the first switch 31 is turned on and the second switch 32 is turned off. When the first drive signal is at a low level and the second drive signal is at a high level, the first switch 31 is turned off and the second switch 32 is turned on. In some embodiments, the first switch 31 or the second switch 32 can be turned on only when the gate voltage of the first switch 31 or the second switch 32 is 15V higher than the source voltage. Therefore, the first drive signal and the second drive signal are usually 15V. However, since the voltage at the source of the second switch 31 (i.e., the connection point 23) is floating, the gate voltage of the first switch 31 is not necessarily 15V higher than the source voltage, resulting in the first switch 31 not necessarily being turned on. Therefore, it is necessary to provide a switching power supply to power the switching conversion device 50 so that the voltage output by the switching conversion device 50 (i.e., the voltage between the second terminal and the third terminal) is equal to the voltage provided by the switching power supply 44 (e.g., 15V).

[0028] Figure 3 Shows Figure 1 FIG. 1 is a schematic diagram of a switching power supply 44 in the magnetic resonance imaging system 10. Figure 4 Shown as Figure 3 FIG. 4 is a schematic diagram of an air core transformer 130 in a switching power supply 44. Figure 3 As shown, the switching power supply 44 includes a first power unit 110, a second power unit 120 and an air-core transformer 130, and the second power unit 120 is electrically coupled to the first power unit 110 through the air-core transformer 130, wherein the switching power supply 44 is configured to operate at a preset frequency, and the multiple of the preset frequency is outside the receiving bandwidth of the magnetic resonance imaging system. In some embodiments, the preset frequency is 1.4 MHz.

[0029] In some embodiments, by setting the switching power supply 44 to operate at a preset frequency, the noise of the switching power supply can be outside the receiving bandwidth of the magnetic resonance imaging system. In other words, the noise generated by the switching power supply cannot be received by the magnetic resonance imaging system and will not interfere with the final magnetic resonance image.

[0030] In some embodiments, the air core transformer 130 includes a non-magnetic core, a first winding 131, and a second winding 132 magnetically coupled to the first winding, and further as Figure 4 As shown, the first winding 131 and the second winding 132 are wound side by side on the non-magnetic core 133. In some embodiments, the first winding 131 and the second winding 132 are wound closely together to increase the coupling coefficient of the air-core transformer 130.

[0031] In some embodiments, the first power unit 110 includes a power amplifier 111 and a first capacitor 112. In some embodiments, the power amplifier 111 is configured to amplify the power of an input signal, the input terminal 101 of the power amplifier 111 is used to receive the input signal, the first terminal 105 of the power amplifier 111 is connected to the power supply 102, and the first capacitor 112 and the first winding 131 of the air-core transformer 130 are connected in series between the second terminal 106 and the third terminal 107 of the power amplifier 111. In some embodiments, the input signal is a synchronous clock signal, and the input signal operates at the preset frequency, for example, 1.4 MHz. In some embodiments, the first capacitor 112 is configured to filter out the DC component of the amplified signal output by the power amplifier 111, so as to output the first signal to the first winding 131.

[0032] In some embodiments, the second power unit 120 includes a second capacitor 121 and a rectifier unit 122. In some embodiments, the second capacitor 121 is connected to the second winding 132 of the air-core transformer 130, and is configured to filter out the DC component in the second signal output by the second winding 132. In some embodiments, the rectifier unit 122 is connected to the second capacitor 121, and is configured to convert the AC component in the second signal into a DC output signal. In some embodiments, the rectifier unit 122 is composed of a diode device.

[0033] In some embodiments, the second power unit 120 further includes an output capacitor 150 connected in parallel with the rectifier 122, which has the function of a low-pass filter to filter out the fluctuation signal in the DC voltage generated by the rectifier 122. It can be understood that in other embodiments, the second power unit 120 can also omit the output capacitor 150 during specific implementation.

[0034] In some embodiments, the second power unit 120 can output a regulated DC voltage (V 0 ) to be applied to the RF coil control device. In some embodiments, the DC voltage (V 0 ) is provided to the voltage conversion device 50 (such as Figure 2 A first end of the device is shown.

[0035] In some embodiments, the switching power supply 44 further includes a bypass unit 140, which is connected between the first winding 131 and the second winding 132, and is configured to bypass the interference of the common mode current caused by the close placement of the first winding 131 and the second winding 132. In some embodiments, the bypass unit 140 includes a bypass capacitor.

[0036] The switching power supply proposed in the present application, on the one hand, adopts an air-core transformer, which can solve the problem that traditional magnetic cores cannot work in a strong magnetic field environment, and provide a highly efficient isolated voltage power supply for the radio frequency coil control device; on the other hand, by setting the switching power supply to work at a preset frequency, the frequency multiple of the preset frequency is outside the receiving bandwidth of the magnetic resonance imaging system, so as to avoid the noise generated by the switching power supply interfering with the accuracy of the magnetic resonance image.

[0037] Some exemplary embodiments have been described above, however, it should be understood that various modifications may be made. For example, if the described techniques are performed in a different order and / or if the components in the described systems, architectures, devices, or circuits are combined in different ways and / or replaced or supplemented by other components or their equivalents, suitable results may be achieved. Accordingly, other implementations also fall within the scope of protection of the claims.

Claims

1. A switching power supply, which is used to power a radio frequency coil control device, wherein the radio frequency coil control device is used to control the flow direction of radio frequency power output by a radio frequency amplifier of a magnetic resonance imaging system, so as to control the selection of a specific type of radio frequency transmitting coil and / or a specific type of radio frequency receiving coil, and the switching power supply comprises: a first power unit and a second power unit; as well as an air-core transformer, wherein the second power unit is electrically coupled to the first power unit through the air-core transformer; The switching power supply is configured to provide a DC voltage to the radio frequency coil control device and operate at a preset frequency, and a multiple of the preset frequency is outside the receiving bandwidth of the magnetic resonance imaging system, and the radio frequency coil control device comprises: A control switch configured to control the output direction of the radio frequency power; a half-bridge circuit, comprising a first switch and a second switch connected in series, wherein a connection point between the first switch and the second switch is connected to the control switch; and A voltage conversion device is connected to the driving end of the first switch and the switching power supply, and is configured to convert a first driving signal into a first control signal to control the first switch.

2. The switching power supply according to claim 1, wherein: The air-core transformer includes a non-magnetic core, a first winding, and a second winding magnetically coupled to the first winding, and the first winding and the second winding are wound side by side on the non-magnetic core. 3 . The switching power supply according to claim 2 , further comprising a bypass unit connected between the first winding and the second winding.

4. The switching power supply according to claim 2, wherein: The first power unit comprises: A power amplifier, used to amplify the power of an input signal; and The first capacitor is connected to the power amplifier and is used to filter out a DC component in the amplified signal to output a first signal to the first winding.

5. The switching power supply according to claim 4, wherein: The input signal operates at the preset frequency.

6. The switching power supply according to claim 4, wherein: The second power unit comprises: a second capacitor connected to the second winding and used for filtering out a DC component in a second signal output by the second winding; and A rectifier unit is connected to the second capacitor and is used to convert an AC component in the second signal into a DC output signal.

7. The switching power supply according to claim 1, wherein: The preset frequency is 1.4 MHz.

8. A magnetic resonance imaging system, comprising: A radio frequency coil assembly, comprising a radio frequency transmitting coil and a radio frequency receiving coil; A radio frequency amplifier, used for outputting radio frequency power to stimulate the radio frequency coil assembly to generate a radio frequency signal; a radio frequency coil control device, which is used to control the output direction of the radio frequency power to control the selection of a specific type of the radio frequency transmitting coil and / or a specific type of the radio frequency receiving coil; and The switching power supply according to any one of claims 1 to 7, which is connected to the radio frequency coil control device and is configured to supply power to the radio frequency coil control device.

9. The magnetic resonance imaging system of claim 8, wherein: The radio frequency coil control device further includes a buffer unit connected to the driving end of the second switch and configured to buffer the second driving signal to control the second switch.

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