Local coil and system for wireless energy transmission
阅读说明:本技术 局部线圈和用于无线能量传输的系统 (Local coil and system for wireless energy transmission ) 是由 A.法克尔梅尔 于 2019-08-14 设计创作,主要内容包括:本发明涉及一种具有能量供应装置的局部线圈、一种由能量发送装置和局部线圈组成的系统以及一种用于运行该系统的方法。局部线圈具有能量存储器、时钟控制器和用于从能量发送装置无线地接收能量的能量接收装置。局部线圈的时钟控制器被设计为与外部时钟源同步。时钟控制器与能量供应装置信号连接,并且时钟控制器被设计为,经由能量接收装置依据同步来控制能量接收。(The invention relates to a local coil having an energy supply, to a system comprising an energy transmission device and a local coil, and to a method for operating the system. The local coil has an energy store, a clock controller and an energy receiving device for wirelessly receiving energy from the energy transmitting device. The clock controller of the local coil is designed to be synchronized with an external clock source. The clock controller is in signal connection with the energy supply device and is designed to control the energy reception via the energy reception device in dependence on the synchronization.)
1. A local coil having an energy supply device (55), the energy supply device (55) having an energy store (57), a clock controller (56) and an energy receiving device for wirelessly receiving energy from an external energy transmitting device (40), wherein the clock controller (56) is designed to be synchronized with an external clock source (42) and the clock controller (56) is in signal connection with the energy supply device (55), and the clock controller (56) is designed to control energy reception via the energy receiving device as a function of the synchronization.
2. Local coil according to claim 1, wherein the clock controller (56) has a synchronization input for synchronizing with an external clock source (42).
3. Local coil according to claim 2, wherein the synchronization input is signal-connected to the energy reception device and has a demodulator in order to demodulate an external synchronization signal received from the energy reception device (55).
4. Local coil according to claim 2, wherein the clock controller (56) is in signal connection with a wireless communication device, and the clock controller (56) or the energy supply device (55) is designed to transmit information about the charging state of the energy store (57) via the communication device.
5. Local coil according to one of the preceding claims, wherein the energy receiving means have an induction coil (58) with detuning means (59) and the clock controller (56) is designed for controlling the detuning means (59).
6. Local coil according to any of the preceding claims, wherein the energy storage (57) is a capacitor, a super capacitor and/or a rechargeable battery.
7. A system consisting of a plurality of local coils (50) according to one of the preceding claims, an energy transmission device (40) and a clock source (42), wherein the clock source (42) is designed to transmit synchronization information to a clock controller (56) of the local coils (50) such that only a true subset of local coils (50) simultaneously receive energy via the energy reception device.
8. System according to claim 7, wherein the clock source (42) is signal-connected to the energy transmission means (40), and the clock source (42) is designed for modulating the energy transmission of the energy transmission means (40).
9. A method for operating a system according to claim 7 or 8, wherein the method has the following steps:
sending (S10) synchronization information by the clock source (42);
receiving (S20), by a clock controller (56) of a local coil (50), the synchronization information;
receiving energy by an energy supply device (55) via an energy receiving device in dependence on the synchronization information (S30).
10. The method of claim 9 with the local coil (50) of claim 5 wherein the step of energy receiving (S30) has the step of changing the state of the detuning means (59) (S31).
11. The method according to claim 9, with the local coil (50) according to claim 3 and with the system according to claim 8, wherein the step of transmitting (S10) has the step of modulating the energy transmission of the energy transmission means (40) with synchronization information (S11), and the step of receiving (S20) has the step of demodulating with a demodulator the signal received from the energy transmission means (40) and forwarding the received synchronization information to the clock controller (56) (S21).
12. The method according to claim 9, having a local coil (50) according to claim 4, wherein the method has the step (S40) of transmitting information about the charging state of the energy store (57) via a communication device.
13. The method of claim 12, wherein the clock source (42) receives information about the state of charge in step (S41) and changes the synchronization information sent in step (S10) in accordance with the information about the state of charge.
Technical Field
The invention relates to a local coil and a system for wireless energy transmission of a local coil, comprising a local coil and an energy transmission device.
Background
A magnetic resonance tomography apparatus is an imaging device which aligns the nuclear spins of an examination subject with a strong external magnetic field in order to image the examination subject and excites the nuclear spins to precess around this alignment by means of an alternating magnetic field. The precession or return of the spins from this excited state to a state with lower energy in turn generates an alternating magnetic field in response, which is also referred to as a magnetic resonance signal, which is received via the antenna.
By means of gradient magnetic fields, a position code is applied to the signals, which can then be correlated with the body element. The received signals are then analyzed and a three-dimensional imaging representation of the object under examination is provided. The resulting display illustrates the spatial density distribution of the spins.
In order to improve the signal-to-noise ratio and to accelerate image acquisition by parallel scanning, more and more receiving antennas are arranged as close as possible to the body of the patient in the form of an antenna matrix, called local coil matrix. Cable connections are usually used for transmitting signals received in the local coil or the local coil matrix. However, the cable also acts as an antenna during the excitation pulse, so that special safety measures, such as a standing wave trap (Mantelwellensperren), must be provided in order to protect the patient from damage. Furthermore, the operation of the cable is also troublesome.
The local coils may also be used to convert or digitize the received magnetic resonance signals and transmit them to the magnetic resonance tomography apparatus. However, a battery is also required for supplying the preamplifier and the converter, which battery can only spend a limited time and thus prevents continuous operation of the magnetic resonance tomography apparatus.
In the case of wireless energy transmission, on the one hand magnetic resonance signals can be disturbed, and on the other hand a plurality of local coils are usually arranged on the patient, so that no exchange is necessary during the examination and valuable examination time of the magnetic resonance tomography apparatus is not wasted. In this case, the wireless energy transmission of the local coils may influence and interfere with one another.
Document DE 102012210507B 4 discloses a local coil for a magnetic resonance imaging system and a magnetic resonance imaging system, wherein the local coil or the magnetic resonance imaging system is designed for wireless transmission of operating energy or a reference signal.
Disclosure of Invention
The object of the invention is therefore to provide a local coil which is easy to handle.
This object is achieved by a local coil according to the invention and a system according to the invention.
The local coil according to the invention has an energy supply. The energy supply device is designed to supply energy to consumers or active components of the local coil during operation. The active component is, for example, a preamplifier, such as a Low Noise Amplifier (LNA), a mixer, an oscillator, an a/D converter or a transmitter for transmitting the received magnetic resonance signals to the magnetic resonance tomography device. The energy supply device is preferably designed to ensure a complete transmission of all magnetic resonance signals of the at least one image acquisition. The energy supply device therefore also has an energy store which is designed to ensure that the transmission takes place even in the event of an interruption or a pause in the wireless energy supply. An exemplary energy store is also given below.
The energy supply device also has an energy receiving device which is designed to receive energy wirelessly from an external energy transmitting device in order to keep the electrical loads of the local coil in operation. In this case, interruptions in the wireless energy transmission are passed through the energy store, wherein the energy receiving device recharges the energy store between these interruptions. The energy receiving means can be, for example, a coil, which receives energy from the energy transmitting means in the near field by induction, without emitting electromagnetic waves into free space on a large scale. Here, "do not emit on a large scale" is understood to mean that less than 50%, 25%, 10%, 5% or 1% of the transmitted energy is emitted into the space.
Furthermore, the local coil according to the invention also comprises a clock controller. The clock controller is designed to be synchronized with an external clock source, as explained in detail below. The clock controller is connected to the energy supply device via a signal connection and is designed to control the energy reception via the energy reception device in accordance with the synchronization. By "control" is understood, in particular, that the clock controller specifies a time interval in which the energy supply device receives energy wirelessly. "dependent" is to be understood in particular to mean that the time points and/or the duration of the time intervals depend on the synchronization.
In an advantageous manner, it can be predetermined by the clock controller and the energy receiving device when the local coil receives energy wirelessly, so that interactions between a plurality of local coils can be avoided.
In a possible embodiment, the clock controller has a synchronization input for synchronizing with an external clock source. It is for example conceivable that the clock controller has an antenna in order to receive an additional synchronization signal. The clock controller can also use the excitation pulses or gradient signals of the magnetic resonance tomography as synchronization signals. It is also conceivable for the clock to be an internal clock which is only synchronized with the magnetic resonance tomography apparatus at longer intervals, for example in a charging tray. Finally, the magnetic resonance tomography apparatus and the clock controller can also be synchronized by an external third clock source.
Advantageously, the synchronization input allows a plurality of local coils and the magnetic resonance tomography apparatus to be synchronized, so that these local coils and the magnetic resonance tomography apparatus operate simultaneously, without interfering with one another or overloading the energy transmission device during the wireless energy supply.
In a conceivable embodiment of the local coil according to the invention, the synchronization input is signal-connected to the energy reception device. The synchronization input has a demodulator which is designed to demodulate an external synchronization signal received from the energy reception device and to forward it to the clock controller.
The demodulator advantageously allows the transmission of the synchronization signal to the clock controller of the local coil without additional signal paths or radio frequencies which could interfere with operation.
In a conceivable embodiment of the local coil according to the invention, the clock controller is in signal connection with the wireless communication device. The clock controller or the energy supply device is designed to transmit information about the charge state of the energy store via the communication device. For example, the information may be transmitted with the MRT signal in a frequency division multiplexed, time division multiplexed, and/or digital manner. However, it is also conceivable to use a separate bidirectional wireless transmission for transmitting control commands that can operate with a lower bandwidth.
In an advantageous manner, the information about the charging state makes it possible to optimally coordinate the energy supply of the plurality of local coils, so that the energy transmission device adequately copes with at a lower power.
In a possible embodiment, the energy reception device of the local coil according to the invention has an induction coil with detuning means, and the clock controller is designed to control the detuning means. The detuning means may be realized by a switchable capacitance or inductance, for example. High frequency switches, such as PIN diodes, are also conceivable, which short or open circuits or lines. The induction coils are preferably designed to obtain energy resonantly by induction in the alternating magnetic field of the respective transmission coil. The clock controller is preferably designed to detune the induction coil in the time interval, wherein the further clock controller of the further local coil switches off its detuning for the wireless energy transmission.
Advantageously, the detuning means switched by the clock controller avoid interactions between the induction coils in different local coils, which interactions can lead to detuning and thus to a deteriorated energy transfer through the coupling of the resonant oscillating circuits.
In a conceivable embodiment, the local coil according to the invention has a capacitor, a super capacitor (Supercap) or a rechargeable battery as an energy store. A combination of a fast chargeable energy storage and an energy storage with a high capacity, such as a super capacitor and a lithium battery, is also conceivable in order to combine a short charging time with a large capacity.
These rechargeable energy stores advantageously enable the energy supply of the local coil to be ensured for brief or even longer interruptions of the wireless energy transmission. Here, the capacitor and the supercapacitor are recharged in a very short time, while the supercapacitor and the rechargeable battery can also spend a longer pause in energy transfer.
The system according to the invention has a plurality of local coils according to the invention, an energy transmission device and a clock source. The clock source is designed as a clock controller which sends a clock signal to the local coil. The clock signal is designed such that only a real subset of the partial coils simultaneously receive energy via the energy reception device. In other words, the encoding in the clock signal in combination with the clock controller of the local coils ensures that only one or some of the local coils receive energy wirelessly at the same time. For example, the clock signal can have a counter in the loop and the local coil has an individual number, so that energy transmission takes place only when the counter corresponds to the number by disabling the detuning device.
In a conceivable embodiment of the system according to the invention, the clock source is signal-connected to the energy transmission device and is designed for modulating the energy transmission of the energy transmission device. For example, the amplitude or frequency may be modulated in order to transmit the counter digitally encoded.
In an advantageous manner, the local coil can thus be synchronized with the clock source without additional signals.
A conceivable embodiment of the method for operating a system has the step of transmitting synchronization information by means of a clock source. For example, the signal for energy transmission can be modulated or a wireless interface for controlling the local coil can be used.
In a further step, the synchronization information is received by a clock controller of the local coil. For this purpose, the energy receiving device can demodulate the signal for energy transmission, for example, and thus forward the modulated synchronization signal to the clock controller via the signal connection. For controlling the local coil, an additional wireless communication interface may also be provided, which receives the synchronization signal and forwards it via a signal connection to the clock controller.
In another step, the energy supply device controls the energy reception via the energy reception device according to the synchronization information. For example, it is also conceivable for the energy control to carry out the energy reception at a point in time or for a duration determined by the synchronization information.
In an advantageous manner, the method according to the invention makes it possible with the system according to the invention to coordinate the energy reception of a plurality of local coils and to achieve a uniform distribution of the load.
In a possible embodiment of the method according to the invention, the step of energy reception has the step of changing the state of the detuning means.
In an advantageous manner, it can be achieved that the induction coil is tuned to the signal wirelessly transmitting energy only during the energy reception. In contrast, the induction coil is detuned for the remaining time, so that undesired interactions, for example due to coupling of different local coils, do not occur, which reduces the efficiency of the energy transfer.
In a conceivable embodiment of the method according to the invention, the synchronization input of the local coil has a demodulator and is connected to the energy reception device in a signal-transmitting manner. And a clock source of the system is in signal connection with the energy transmitting device. Here, the step of transmitting has a step of modulating energy transmission of the energy transmission device with synchronization information of the clock source, and the step of receiving has a step of demodulating a signal received from the energy transmission device with a demodulator and forwarding the received synchronization information to the clock controller.
The transmission of the synchronization information by means of the signal for energy transmission advantageously eliminates an additional wireless communication path which could cause interference.
In a possible embodiment of the method according to the invention, the local coil has a wireless communication device which is in signal connection with the clock controller. The method has the step of transmitting information about the charging state of the energy store via the communication device. For example, a narrowband communication means can be provided via radio, with which the wireless local coil obtains the setting commands and transmits status information. It is also conceivable that the information about the wireless connection is time, frequency or digitally multiplexed together with the magnetic resonance signals.
Advantageously, the charging of the individual local coils can be optimized by the clock controller, so that the power requirements of the energy transmission device and the SAR load are minimized.
In a conceivable embodiment of the method according to the invention, the clock source receives the information about the charging state in one step and in the step of transmitting changes the transmitted synchronization signal in dependence on the information about the charging state.
Advantageously, the clock source can thereby match the charging of the local coil to the charging state of the local coil and accelerate or optimize the charging of the local coil.
Drawings
The above features, characteristics and advantages of the present invention and the manner of attaining them will become more apparent and the invention will be better understood by reference to the following description of embodiments taken in conjunction with the accompanying drawings.
In the drawings:
figure 1 shows an exemplary schematic diagram of a magnetic resonance tomography apparatus with an antenna according to the invention;
FIG. 2 shows an exemplary schematic diagram of a local coil according to the present invention;
fig. 3 shows an exemplary schematic representation of a magnetic resonance tomography apparatus with an energy transmission device according to the invention;
fig. 4 shows a schematic flow chart of a method according to the invention.
Detailed Description
Fig. 1 shows a schematic view of an embodiment of a magnetic
The
The
The
The
The
The high-frequency signals generated by the high-
The
The magnetic resonance signals are typically transmitted from the local coil to the magnetic
In order to be able to provide a wireless energy supply, the magnetic
If the
However, if two or more
The local coil shown in fig. 2 with the
The
Active components, for example a
The alternating current in the induction coil, which is induced by the alternating magnetic field, is then rectified in the
The
Furthermore, the
The
The detuning of the
For example, a synchronization of the
There is also a solution in which the energy supply means 55 forward the charging state of the
A corresponding
The magnetic
The frequency of the alternating current generated by the energy transmission means 40 is preferably chosen such that the harmonics do not coincide with the frequency of the magnetic resonance signal or with intermediate frequencies used in the subsequent analysis.
In a conceivable embodiment, the
In further embodiments, it is also conceivable for the synchronization information to be transmitted by the
Depending on the embodiment, the
It is contemplated herein that
An exemplary flow chart of the method according to the invention is shown in fig. 4.
In step S10, the
In step S20, the
In step S30, the
It is also conceivable in an embodiment of the method according to the invention that in step S40 the
Preferably, the
Although the invention has been illustrated and described in detail by means of preferred embodiments, the invention is not limited to the disclosed examples and other solutions can be derived therefrom by a person skilled in the art without departing from the scope of protection of the invention.
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