Thermal therapy device

• US 20070179576A1
• Filed: 04/22/2005
• Published: 08/02/2007
• Est. Priority Date: 04/23/2004
• Status: Active Grant

• Current Assignee: Kanazawa University, Komatu Power Tron Co., Ltd.
• Original Assignee: Kanazawa University Technology Licensing Organization Limited, Komatu Power Tron Co., Ltd.
• Inventors: Nagano, Isamu, Igarashi, Kouichi
• Granted Patent: US 7,833,258 B2
• Time in Patent Office: Days
• US Class Current: 607/96
• CPC Class Codes: A61N 1/406 using implantable thermoseeds or injected particles for localized hyperthermia preparations of seeds and particles A61K41/0052

Abstract

There is provided a thermal therapy device that is capable of following changes in the resonance frequency even if the resonance frequency of the series resonance circuit on the secondary side changes significantly and generating a magnetic field of a required intensity for heating the affected portion. The thermal therapy device comprises an inverter circuit (2) connected to the primary side of a transformer (1), a series resonance circuit (5) connected to the secondary side of the transformer and including a magnetic field generation coil (3) and a resonance controller (4), and a controller (20) for determining the resonance frequency based on the secondary current. The therapy operation mode may be a measurement mode and an operation mode which are alternately repeated. During the measurement mode the resonance frequency of the series resonance circuit (5) is measured, while during the operation mode a drive signal of said measured resonance frequency is supplied from the controller (20) to the inverter circuit (2). Accordingly, the frequency of the drive signal to be supplied to the inverter circuit can follow the resonance frequency even if the impedance of the series resonance circuit (5) or the like varies during therapy.

Claims

1. A thermal therapy device comprising a transformer, an inverter circuit connected to the primary side of said transformer, a series resonance circuit connected to the secondary side of said transformer and including a magnetic field generation coil and a resonance condenser and a controller for supplying a drive signal to said inverter circuit in such a way that the frequency of a current passing in said series resonance circuit conforms with the resonance frequency thereof, the device generating a magnetic field of high frequency toward the patient'"'"'s affected portion;

wherein said thermal therapy device comprises a current detecting means for detecting the current passing in said series resonance circuit; and

said controller comprises a mode setting means for alternately switching between an operation mode during which a magnetic field of high frequency is generated toward the patient'"'"'s affected portion and an measurement mode during which the resonance frequency of said series resonance circuit is measured to set the mode,

a resonance frequency determining means for receiving an input of a signal of a current having been detected by said current detecting means and determining said resonance frequency based upon said signal during the measurement mode set by said mode setting means, and

a drive signal supplying means for supplying a drive signal of a switching frequency to said inverter circuit using the resonance frequency having been determined by said resonance frequency determining means during the operation mode set by said mode setting means.

2. The thermal therapy device according to claim 1, wherein the drive signal supplied by said drive signal supplying means is a step signal or a white noise signal.

3. The thermal device according to claim 1, wherein the drive signal supplied by said drive signal supplying means is a sweep signal of sequentially changing frequency.

4. The thermal therapy device according to claim 1, wherein said resonance frequency determining means receives the current signal having been detected by the current detecting means and subjects said signal to a frequency analysis using fast Fourier transformation to obtain a frequency spectrum and determine said resonance frequency during the measurement mode set by the mode setting means.

5. The thermal therapy device according to claim 1, wherein said magnetic field generation coil is a bread-shaped coil having a current path that extends in the shape of a spiral in the coil plane.

6. The thermal therapy device according to claim 5, further comprising a core plate facing the coil surface opposite to the patient'"'"'s affected portion, seen from said magnetic field generation coil.

7. The thermal therapy device according to claim 5, wherein said magnetic field generation coil has the flexibility and changes shape.

8. A thermal therapy method for generating a magnetic field of high frequency using a transformer, an inverter circuit connected to the primary side of said transformer, a series resonance circuit connected to the secondary side of said transformer and including a magnetic field generation coil and a resonance condenser and a controller for supplying a drive signal to said inverter circuit in such a way that the frequency of a current passing in said series resonance circuit conforms with the resonance frequency thereof, comprising the steps of:

alternately switching between an operation mode during which a magnetic field of high frequency is generated toward the patient'"'"'s affected portion and a measurement mode during which the resonance frequency of said series resonance circuit is measured to set the mode;

determining the resonance frequency by receiving an input of a signal of a current passing in said series resonance circuit during said measurement mode; and

supplying a drive signal of a switching frequency based on the determined resonance frequency to said inverter circuit during the operation mode.

9. The thermal therapy method according to claim 8, wherein said drive signal is a step signal or a white noise signal.

10. The thermal therapy method according to claim 8, wherein said drive signal is a sweep signal of sequentially changing frequency.

11. The thermal therapy method according to claim 8, wherein said step of determining the resonance frequency is a step of determining said resonance frequency by receiving an input of a signal of a current passing in said series resonance circuit and subjecting said signal to a frequency analysis using fast Fourier transformation to obtain a frequency spectrum.