Coupling method for resonant diathermy and other bio-tissue heating applicators
Inventors
Assignees
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Publication Number
US-9050166-B2
Publication Date
2015-06-09
Expiration Date
Abstract
A diathermy apparatus includes a cylindrical coil (24) defining an opening (42), a pair of capacitors of substantially similar capacitance (20 and 22), each capacitor connected to one end of the coil, an RF signal source (26), and a balun (28) connected between the RF signal source (26) and the pair of capacitors (20 and 22). The balun (28) is operative for converting an unbalanced signal received from the RF signal source (26) into a balanced signal supplied to coil (24) via the pair of capacitors (20 and 22). Desirably, the cylindrical coil is a conical cylindrical (or cone-shaped) spiral coil.
Core Innovation
The invention relates to a resonant diathermy apparatus that uses a cylindrical coil having a first end and a second end, where resonant diathermic heating is provided with capacitive coupling to both ends of the coil. Instead of inductive coupling, the apparatus provides a first capacitor connected to the first end of the coil and a second capacitor connected to the second end of the coil, forming a symmetric capacitive coupling arrangement.
An RF signal source supplies an unbalanced signal to a balun that converts the unbalanced signal into a balanced signal. The balun outputs the balanced signal on a first lead coupled to the first capacitor and a second lead coupled to the second capacitor, impressing voltage on each capacitor and causing the coil to be impressed with a corresponding voltage, consistent with the stated responses to the RF signal.
The symmetric capacitive coupling and the balanced drive provided by the balun reduce common-mode voltage and leakage and allow the effective ground point of the coil to drift with patient position while maintaining stable performance. The arrangement is described as providing more uniform symmetric electromagnetic fields for more uniform heating, and as reducing detuning and unbalancing issues.
Claims Coverage
The partial content identifies one independent claim (clm-00001). Its main inventive features are centered on a cylindrical coil driven at both ends through capacitors by a balun converting an unbalanced RF signal into a balanced signal, with a stated impressed-voltage relationship between the capacitors and the coil.
Symmetric capacitive coupling of opposite coil ends
A cylindrical coil having a first end and a second end with a first capacitor connected to the first end and a second capacitor connected to the second end.
Balun-driven balanced capacitive excitation from an unbalanced RF source
A balun connected to the first capacitor via a first lead and connected to the second capacitor via a second lead, where an RF signal source supplies an unbalanced signal to the balun which converts the unbalanced signal into a balanced signal output on the first and second leads.
Stated impressed voltages on capacitors and coil in response to RF signal
In response to the RF signal source outputting an RF signal, each capacitor has about 500 Vac impressed thereon, whereupon the coil has impressed thereon about 1000 Vac.
Across the identified independent claim, the inventive concept is a resonant diathermy apparatus that drives a cylindrical coil at opposite ends using two capacitors under a balun that converts an unbalanced RF signal to a balanced signal, with an explicit impressed-voltage relationship between the capacitors and the coil.
Stated Advantages
Uniform symmetric electromagnetic fields for more uniform heating.
Reduced common-mode voltage and leakage.
Allows the effective ground point of the coil to drift with patient position while maintaining stable performance.
Reduces detuning and unbalancing issues.
An optional impedance matching circuit/network is available.
An optional adjustable parallel tuning capacitor is available.
Documented Applications
Resonant diathermic heating using a coil having an opening configured to receive a body part.
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