Detuning magnetic resonance radio frequency coil without external direct current circuit

[0028] Embodiment one:

[0029] like image 3 As shown, in this embodiment, the detunable magnetic resonance radio frequency coil without an external DC circuit includes an active detuning circuit and a resonant capacitor connected in series, and there are two copper-coated printed circuit boards between the active detuning circuit and the resonant capacitor. There are parallel resonant inductors, and the two parallel resonant inductors form a loop and are connected to the DC power supply driving the active detuning circuit. In most radio frequency coils, the inductance of the coil unit is one or two layers of copper in the double-layer PCB, that is, one or two layers of the top layer and the bottom layer of the double-sided PCB together form the inductance of the coil unit. The present invention uses such double-layer copper cladding, and through appropriate design changes, direct current can flow through the original radio frequency signal lines, thereby eliminating additional direct current lines and reducing the above-mentioned various negative effects.

[0030]In this embodiment, one end of the two parallel resonant inductors is connected together through an active detuning circuit located at the output end of the magnetic resonance radio frequency coil, and the other ends of the two parallel resonant inductors are respectively grounded through a grounding capacitor, and one grounding capacitor is connected to a choke The coils are connected in parallel, and the non-ground terminal of the other grounded capacitor is connected to the DC power supply driving the active detuning circuit. In this embodiment, one resonant inductance is 1, 2, 3, 4, 5, and the other resonant inductance is 11, 21, 31, 41, 51, and the resonant inductances 5 and 51 pass through the active detuning at the output end of the magnetic resonance radio frequency coil The circuit is connected, the resonant inductor 1 is grounded through the grounding capacitor C41, the resonant inductor 11 is grounded through the grounding capacitor C4, the grounding capacitor C4 is connected in parallel with a choke coil choke10, and the non-grounded end of the grounding capacitor C41 is connected to the DC power supply ( DC supplier) connected. The DC circuit where the DC current completely passes through the RF circuit is: +DC supplier (DC power supply) → choke1 → resonant inductor 1 → diode D3 → inductor L3 → resonant inductor 2 → choke2 → resonant inductor 3 → inductor L2 → diode D2 → resonance Inductor 4→choke4→resonant inductor 5→inductor L1→diode D1→choke5→resonant inductor 51→choke6→resonant inductor 41→choke7→resonant inductor 31→choke8→resonant inductor 21→choke9→resonant inductor 11→choke10→GND.

[0031] This embodiment not only does not introduce additional DC wires, but also the distance between the two wires of the DC wires is very small (the bottom layer and the top layer of the flexible double-layer PCB are used as inductance 1, 2, 3, 4, 5 and inductance 11 respectively. , 21, 31, 41, 51, the distance between them is <1mm), almost no additional magnetic field will be generated to affect the uniformity of the magnetic resonance magnetic field.

[0032] In this embodiment, the resonant capacitors are respectively connected in parallel with one choke coil. For example, the resonant capacitor C7 is connected in parallel with a choke coil choke7, the resonant capacitor C71 is connected in parallel with a choke coil choke2, the resonant capacitor C6 is connected in parallel with a choke coil choke6, and the resonant capacitor C61 is connected in parallel with a choke coil choke4. In addition, a series choke coil choke1 is provided at the input end of a DC power supply (DC supplier).

[0033] In this embodiment, among the two parallel resonant inductors, one resonant inductor is arranged on the top layer of the printed circuit board, and the other resonant inductor is arranged on the bottom layer of the printed circuit board. Additionally, the present embodiments are not entirely limited to a detunable magnetic resonance RF coil. A direct current circuit can also be formed between a plurality of detunable magnetic resonance radio frequency coils adjacent to each other without introducing any additional direct current lines by adopting this embodiment, and the uniformity of the main magnetic field will not be affected by the existence of direct current. advantage.

[0034] In this embodiment, the active detuning circuit includes two first capacitors respectively used to connect to one of the two resonant inductors, the two ends of the two first capacitors are respectively connected in parallel through the second capacitor, and one first A capacitor is connected in parallel with a choke coil, and another first capacitor, an inductor and a diode are sequentially connected in series to form a basic detuning circuit. Taking the first active detuning circuit on the input side of the DC power supply (DC supplier) driving the active detuning circuit as an example, the active detuning circuit includes two first capacitors C3 and C31, the input terminal of the first capacitor C3 and the resonant inductor 11 , the output end is connected to the resonant inductor 21 , the input end of the first capacitor C31 is connected to the resonant inductor 1 , and the output end is connected to the resonant inductor 2 . One ends of the first capacitors C3 and C31 are connected in parallel through the second capacitor C32, and the other ends of the first capacitors C3 and C31 are connected in parallel through the second capacitor C33. The first capacitor C3 is connected in parallel with a choke coil choke9; the first capacitor C31 is sequentially connected in series with the inductor L3 and the diode D3 to form a basic detuning loop. The structures of other active detuning circuits are the same and will not be repeated here.

[0035] Embodiment two:

[0036] like Figure 4 As shown, this embodiment is basically the same as Embodiment 1, the difference is that the active detuning circuit adopts two parallel basic detuning circuits: the active detuning circuit includes two resonant inductances used to connect with one of the two resonant inductances The connected first capacitors, the two first capacitors are respectively connected in series with the inductor and the diode in sequence to form two parallel basic detuning circuits. Taking the first active detuning circuit on the input side of the DC power supply (DC supplier) driving the active detuning circuit as an example, the active detuning circuit includes two first capacitors C3 and C31, the input terminal of the first capacitor C3 and the resonant inductor 11 , the output end is connected to the resonant inductor 21 , the input end of the first capacitor C31 is connected to the resonant inductor 1 , and the output end is connected to the resonant inductor 2 . The first capacitor C3, the inductor L33, and the diode D33 are sequentially connected in series to form the first basic detuning circuit; the first capacitor C31, the inductor L3, and the diode D3 are connected in series to form the first basic detuning circuit. A second basic detuned circuit parallel to the basic detuned circuit.