Multi-channel RF transmit system
阅读说明：本技术 多通道rf发射系统 (Multi-channel RF transmit system ) 是由 P·韦尔尼科尔 C·洛斯勒 于 2019-02-12 设计创作，主要内容包括：一种特别用于在磁共振检查系统中使用的多通道RF发射系统(1),其包括多个RF通道(18、19),其中,所述RF通道(18、19)中的每个RF通道具有RF放大器。所述多通道RF发射系统(1)还包括：电源设备(2),其被配置为向所述放大器(4、5)供应功率；第一电容器组(6),其中,所述第一电容器组(6)被连接到所述电源设备(2)并且被连接到第一RF放大器(4)；第二电容器组(7),其中,所述第二电容器组(7)被连接到所述电源设备(2)并且被连接到第二RF放大器(5),并且第三电容器组(8)也被连接到所述电源设备(2)。所述第三电容器组(8)被连接到DC开关(9),其中,所述DC开关(9)被配置为将由所述第三电容器组(8)供应的功率切换到第一放大器(4)或第二放大器(5)。因此,公开了一种多通道RF发射系统(1),其中,离散储存能量的全部可用能力的部分能够被引导到一个或其他RF放大器通道(18、19),从而实现DC电源供应链的更有效和节省成本的设计。(A multi-channel RF transmit system (1), in particular for use in a magnetic resonance examination system, comprising a plurality of RF channels (18, 19), wherein each of the RF channels (18, 19) has an RF amplifier. The multi-channel RF transmit system (1) further comprises: a power supply device (2) configured to supply power to the amplifiers (4, 5); a first capacitor bank (6), wherein the first capacitor bank (6) is connected to the power supply device (2) and to a first RF amplifier (4); a second capacitor bank (7), wherein the second capacitor bank (7) is connected to the power supply device (2) and to a second RF amplifier (5), and a third capacitor bank (8) is also connected to the power supply device (2). The third capacitor bank (8) is connected to a DC switch (9), wherein the DC switch (9) is configured to switch power supplied by the third capacitor bank (8) to the first amplifier (4) or the second amplifier (5). Thus, a multi-channel RF transmit system (1) is disclosed, wherein part of the total available capacity of discrete stored energy can be directed to one or other RF amplifier channels (18, 19), thereby enabling a more efficient and cost-effective design of the DC power supply chain.)
1. A multi-channel RF transmit system (1) for a magnetic resonance examination system, comprising:
a plurality of RF channels (18, 19), wherein each of the RF channels (18, 19) has an RF amplifier (4, 5) configured to amplify an input signal (11, 13) and to output the amplified input signal (11, 13) as an output signal (12, 14),
a power supply device (2) configured to supply power to the amplifiers (4, 5),
at least a first capacitor bank (6), wherein the first capacitor bank (6) is connected to a conductor path (20) between the power supply device (2) and a first RF amplifier (4), wherein the first capacitor bank (6) is configured to supply power to the first amplifier (4) together with the power supply device (2),
at least a second capacitor bank (7), wherein the second capacitor bank (7) is connected to a conductor path (21) between the power supply device (2) and a second RF amplifier (5), wherein the second capacitor bank (7) is configured to supply power to the second amplifier (5) together with the power supply device (2),
at least a third capacitor bank (8), wherein the third capacitor bank (8) is connected to a conductor path (23) between the power supply device (2) and a DC switch (9), wherein the third capacitor bank (8) is configured to supply additional power, wherein the DC switch (9) is configured to switch the additional power supplied by the third capacitor bank (8) to the first amplifier (4) or the second amplifier (5), and
a controller (3) configured to control the amplifiers (4, 5) in dependence of RF requirements (10), the controller being configured to receive sensor data from sensors monitoring a status of the capacitor banks (6, 7, 8), the controller being configured to compare the sensor data with a database, and the controller being configured to control the DC switch (9) in dependence of the comparison of the sensor data with the database.
2. The multi-channel RF transmit system (1) of the preceding claim, wherein two or more capacitor banks (8) are connected to the power supply device (2), wherein each capacitor bank (8) is connected to a DC switch (9) configured to supply additional power.
3. The multi-channel RF transmit system (1) of any one of the preceding claims, wherein the DC switch (9) is a solid-state switch.
4. The multi-channel RF transmit system (1) of any one of the preceding claims, wherein the DC switch (9) is a switch matrix.
5. The multi-channel RF transmit system (1) of any one of the preceding claims, wherein the power supply device (2) is segmented into a plurality of segments (15, 16, 17), wherein each segment (15, 16, 17) is capable of providing power.
6. The multi-channel RF transmit system (1) of the preceding claim, wherein at least one capacitor bank (6, 7, 8) is connected to a segment (15, 16, 17) of the power supply device (2).
7. The multi-channel RF transmit system (1) according to any one of claims 5 to 6, wherein the segments (15, 16, 17) are independent of each other.
8. The multi-channel RF transmit system (1) according to any one of the preceding claims, wherein the controller (3) is connected to a self-learning database.
9. A magnetic resonance examination system comprising a multi-channel RF transmit system (1) according to one of the preceding claims.
10. A method for operating a multi-channel RF transmit system (1) in a magnetic resonance examination system, the method comprising the steps of:
providing the multi-channel RF transmit system (1) with a plurality of RF channels (18, 19), wherein each of the RF channels (18, 19) has an RF amplifier configured to amplify an input signal (11, 13) and to output the amplified input signal (11, 13) as an output signal (12, 14),
providing a power supply device (2) configured to supply power to the amplifiers (4, 5),
providing at least a first capacitor bank (6), wherein the first capacitor bank (6) is connected to a conductor path (20) between the power supply device (2) and a first RF amplifier (4), wherein the first capacitor bank (6) is configured to supply power to the first amplifier (4) together with the power supply device (2),
providing at least a second capacitor bank (7), wherein the second capacitor bank (7) is connected to a conductor path (21) between the power supply device (2) and a second RF amplifier (5), wherein the second capacitor bank (6) is configured to supply power to the second amplifier (5) together with the power supply device (2),
providing at least a third capacitor bank (8), wherein the third capacitor bank (8) is connected to a conductor path (23) between the power supply device (2) and a DC switch (9),
wherein the third capacitor bank (8) is configured to supply additional power,
wherein the DC switch (9) is configured to switch the power supplied by the third capacitor bank (8) to the first amplifier (4) or the second amplifier (5),
providing a controller (3) configured to control the amplifiers (4, 5) and the DC switch (9) in accordance with RF requirements (10) and configured to acquire sensor data from sensors monitoring the status of the capacitor banks (6, 7, 8),
switching the power supplied by the third capacitor bank (8) to the first amplifier (4) or the second amplifier (5) based on comparing the sensor data to a database.
11. Method for operating a multi-channel RF transmit system (1) according to claim 10, further comprising the steps of:
the magnetic resonance examination is started and,
a magnetic resonance method is selected in which the magnetic resonance signal is detected,
the controller (3) acquires sensor data from sensors monitoring the status of the capacitor banks (6, 7, 8),
comparing the sensor data to a database,
selecting, by the controller (3), the switch (9) based on the sensor data,
a magnetic resonance sequence is started and the magnetic resonance imaging system,
the procedure is repeated after the magnetic resonance sequence has ended.
12. Method for operating a multi-channel RF transmit system (1) according to claim 11, further comprising the steps of:
providing the switch, wherein the switch is a solid state switch,
switching the power during the magnetic resonance sequence.
13. A computer program comprising computer program code adapted to perform the method according to any of claims 10-12 when said program is run on a programmable microcomputer.
Technical Field
The present invention relates to the field of multi-channel RF transmit systems, and in particular to a multi-channel RF transmit system for a magnetic resonance examination system, a magnetic resonance examination system comprising such a multi-channel RF transmit system, a method of operating such a multi-channel RF transmit system, and a computer program comprising computer program code adapted to perform the method.
Background
As is well known in the art, magnetic resonance examination systems require a special type and performance of RF transmit chains. In particular, the RF transmit chain must handle pulse power capability on the order of 10kW, within 1ms, and with short-term high duty cycle RF pulses of about 100 ms. For the RF chain, MOSFETS are often used for MRI amplifiers, wherein their operating characteristics depend on the bias point IdqAnd a drain voltage Vds. The MOSFETS are put together to form a typical MRI amplifier with 16kW forward power. DC drain voltage VdsSupplied from a power supply apparatus capable of supplying CW power of about kW. Especially for optimized RF chains, it is challenging to apply short-term high duty cycle pulses in imaging, since the power supply has to achieve high energy requirements in a short time frame.
Prior art solutions for overcoming these drawbacks utilize capacitor banks to store electrical energy and make it available for a short period of time. During and after the RF pulse, the capacitor bank will be charged before the next pulse starts. Typically, the capacitance is about 100mF, which is typically achieved by grouping a plurality of electrolytic capacitors together.
US 2017/0176555a1 discloses a magnetic resonance imaging apparatus wherein a capacitor bank is connected to a power supply device and a corresponding amplifying amplifier. The capacitor bank temporarily stores input power from the power supply device and discharges the stored power to the amplifying amplifier when necessary. Specifically, when it becomes necessary to pass a large current through the gradient coils of all the axes in a short time, there may be a case where the necessary power supply amount temporarily exceeds the power that can be supplied by the power supply device. Even in such a case, power can be stably supplied to the gradient coil due to the presence of the capacitor bank.
Disclosure of Invention
In known multi-channel RF transmit systems as described above, the RF requirements from the individual RF channels are often unequal in RF power and phase. It is necessary to apply setting conditions for the relative phase and relative power of the employed RF power amplifiers to achieve the required RF shimming for optimizing the homogeneity of the RF magnetic excitation field, wherein one RF power amplifier has to provide much more power than the others, even up to its maximum rated power. In such a case, the maximum rated power may be reached quickly, while the available power of the other amplifiers remains unused. In principle, the DC supply chain for each individual RF amplifier can be designed such that each chain is capable of providing sufficient DC power to reach the practical limits defined by patient safety limits. This approach results in a DC supply chain in which the available DC power is over-specified, resulting in a cost-inefficient design. Another option would be to share the DC supply chain, where different RFAs share the same supply, which may then be more cost effective. However, the individual amplifier performance may depend on the performance of another RFA, for example when a strongly driven RFA causes a voltage drop of the DC voltage that is intended to be stabilized.
It is an object of the present invention to achieve an RF transmit system in which part of the total available capacity of discrete stored energy can be directed to one or other RF amplifier channels, thereby enabling a more efficient, cost-effective and decoupled design of the DC power supply chain. Furthermore, it is an object of the invention to distribute the DC power more equally over the RF channels.
According to the invention, this object is solved by the subject matter of the independent claims. Preferred embodiments of the invention are described in the dependent claims.
In one aspect of the invention the object is achieved by a multi-channel RF transmit system for a magnetic resonance examination system, the multi-channel RF transmit system comprising:
a multi-channel RF transmit system for a magnetic resonance examination system, comprising:
a plurality of RF channels, wherein each of the RF channels has an RF amplifier configured to amplify an input signal and configured to output the amplified input signal as an output signal,
a power supply device configured to supply power to the amplifier,
at least a first capacitor bank, wherein the first capacitor bank is connected to a conductor path between the power supply device and a first RF amplifier, wherein the first capacitor bank is configured to supply power to the first amplifier together with the power supply device,
a second capacitor bank, wherein the second capacitor bank is connected to a conductor path between the power supply device and a second RF amplifier, wherein the second capacitor bank is configured to supply power to the second amplifier with the power supply device,
at least a third capacitor bank, wherein the third capacitor bank is connected to a conductor path between the power supply device and a DC switch, wherein the third capacitor bank is configured to supply additional power, wherein the DC switch is configured to switch the power supplied by the third capacitor bank to the first amplifier or the second amplifier, and
a controller configured to control the amplifier and the DC switch according to sensor data.
One advantage of the proposed multi-channel RF transmit system is that: unequal RF power requirements for individual RF channels can be overcome by directing a portion of the total available capacity of the discrete stored energy to one or the other RF amplifiers, depending on the actual RF requirements. The redistribution of power from the capacitor banks allows for more efficient or reasonable distribution of the available DC power over the RF channels. The size (capacitance) ratio of the capacitor bank depends on the MR system (field strength) and the coil type. Convenient ratios can be readily determined using system usage statistics in the field.
In a preferred embodiment, the power supply device is segmented into a plurality of segments, wherein each segment is capable of providing power. The segmentation of the DC power chain provides a flexible and cost-effective way in which the functionality of the power supply device can be shared between the amplifier modules.
In a preferred embodiment, two or more capacitor banks are connected to the power supply device, wherein each capacitor bank is connected to a DC switch configured to supply additional power.
In another preferred embodiment, the DC switch is a solid state switch. The solid state switch is easy to implement as it can be implemented such that the switching is only done when the current is zero, wherein the gate bias is set to disable the transistor. Another advantage is that solid state switching is fast and switching of power can be done between different MR sequences or even during an MR sequence.
In a preferred embodiment, the DC switch is a switch matrix. The switch matrix is advantageous for switching power between a plurality of capacitor banks and a plurality of amplifiers.
In another preferred embodiment, the power supply device is segmented into a plurality of segments, wherein each segment is capable of providing power. The segmentation of the power supply device is advantageous in that it is flexible and that a particular segmentation of the power supply device is capable of providing different voltages to the amplifier and the capacitor bank.
In a preferred embodiment, the at least one capacitor bank is connected to a segment of the power supply device.
In another preferred embodiment, the segments are independent of each other.
In a preferred embodiment, the controller obtains input signals from sensors monitoring the state of the capacitor bank.
In another preferred embodiment, the controller is connected to a self-learning database.
In another aspect of the invention the object is achieved by a magnetic resonance examination system comprising a multi-channel RF transmit system as disclosed above.
In another aspect of the invention the object is achieved by a method of operating an embodiment of an RF transmit system of a magnetic resonance examination system as disclosed herein above. The method comprises the following steps:
providing a multi-channel RF transmit system having a plurality of RF channels, wherein each of the RF channels has an RF amplifier configured to amplify an input signal and configured to output the amplified input signal as an output signal,
providing a power supply device configured to supply power to the amplifier,
providing at least a first capacitor bank, wherein the first capacitor bank is connected to a conductor path between the power supply device and a first RF amplifier (4), wherein the first capacitor bank is configured to supply power to the first amplifier together with the power supply device,
providing a second capacitor bank, wherein the second capacitor bank is connected to a conductor path between the power supply device and a second RF amplifier, wherein the second capacitor bank is configured to supply power to the second amplifier together with the power supply device,
providing at least a third capacitor bank, wherein the third capacitor bank is connected to a conductor path between the power supply device and a DC switch,
wherein the third capacitor bank is configured to provide additional power,
wherein the DC switch is configured to switch power supplied by the third capacitor bank to the first amplifier or the second amplifier,
providing a controller configured to control the amplifier and the DC switch according to RF requirements,
switching power supplied by the third capacitor bank to the first amplifier or the second amplifier based on sensor data.
In a preferred embodiment, the method further comprises the steps of:
the magnetic resonance examination is started and,
a magnetic resonance method is selected in which the magnetic resonance signal is detected,
the controller (3) acquires sensor data from sensors monitoring the status of the capacitor banks (6, 7, 8),
comparing the sensor data to a database,
selecting a switch (9) by the controller (3) depending on the sensor data,
a magnetic resonance sequence is started and the magnetic resonance imaging system,
the procedure is repeated after the end of the magnetic resonance sequence.
In another preferred embodiment, the method further comprises the steps of:
the switches are solid state switches and the power supply is switched by the switches between different MR sequences.
In a preferred embodiment, the method further comprises the steps of:
providing a switch, wherein the switch is a solid state switch,
switching the power supply during the MR sequence.
In a further aspect of the invention the object is achieved by a computer program comprising computer program code adapted to perform a method or for use in a method according to claim 6 when said program is run on a programmable microcomputer.
Drawings
These and other aspects of the invention are apparent from and will be elucidated with reference to the embodiments described hereinafter. Such embodiments, however, do not necessarily represent the full scope of the invention, and reference is made therefore to the claims herein for interpreting the scope of the invention.
In the drawings:
fig. 1 shows a schematic view of a part of a magnetic resonance examination system comprising an embodiment of the RF transmission system according to a preferred embodiment of the invention.
Fig. 2 shows a flow chart according to a preferred embodiment of the present invention.
REFERENCE SIGNS LIST
Multi-channel RF transmit
A first RF amplifier 4
A
First capacitor bank 6
Third capacitor bank 8
Detailed Description
Fig. 1 shows a schematic illustration of a part of an embodiment of a magnetic resonance examination system, wherein a two-channel RF transmit
Fig. 2 shows a flow chart according to a preferred embodiment of the present invention. The flowchart starts with a
While the invention has been illustrated and described in detail in the drawings and foregoing description, such illustration and description are to be considered illustrative or exemplary and not restrictive; the invention is not limited to the disclosed embodiments. Other variations to the disclosed embodiments can be understood and effected by those skilled in the art in practicing the claimed invention, from a study of the drawings, the disclosure, and the appended claims. In the claims, the word "comprising" does not exclude other elements or steps, and the indefinite article "a" or "an" does not exclude a plurality. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage. Any reference signs in the claims shall not be construed as limiting the scope. Further, for clarity, reference numerals may not be provided on all elements in the drawings.
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