Temperature independent method and system for applying TTFields
A system and method for delivering TTFields are herein described. The system comprises, a first port operable to receive a lead of a first pad, a second port operable to receive a lead of a second pad, an electric field generator having circuitry operable to generate an electric signal having a frequency, a current, and a voltage, the frequency in a range of about 50 kHz to about 1 MHz, the circuitry operable to supply the electric signal to the first port and the second port, and to control the current to maintain the current within plus or minus 5% of a current threshold during a period of time in which at least one of a measured voltage and a measured impedance is below a threshold, and a power supply operable to supply power to the electric field generator.
1 . A system for generating TTFields, comprising:
a first port operable to receive a lead of a first pad;
a second port operable to receive a lead of a second pad;
an electric field generator having circuitry operable to generate an electric signal having a frequency, a current, and a voltage, the frequency in a range of 50 kHz to 500 kHz, the circuitry operable to supply the electric signal to the first port and the second port, to determine a measured voltage and a measured impedance of the electric signal between the first port and the second port, and to control the current to maintain the current within plus or minus 5% of a current threshold during a period of time in which at least one of the measured voltage and the measured impedance is below a threshold; and
a power supply operable to supply power to the electric field generator.
2 . The system of claim 1 , wherein the threshold is a voltage threshold, and wherein the circuitry includes a voltmeter operably connected to the first port and the second port, and further comprises monitoring a voltage between the first port and the second port with the voltmeter and upon the voltage reaching a voltage threshold, maintaining the voltage within a range of plus or minus 5% of the voltage threshold.
3 . The system of claim 1 , wherein the threshold is a voltage threshold, and wherein the circuitry includes a voltmeter operably connected to the first port and the second port, and further comprises monitoring a voltage between the first port and the second port with the voltmeter and upon the voltage reaching a voltage threshold, maintaining the voltage within a range of 95% to 100% of the voltage threshold.
4 . The system of claim 3 , wherein the current threshold is within a range of 1.5 A to 3 A for a cranial system and between 1.5 A to 5 A for a torsal system, and the voltage threshold is within a range of 20 V to 240 V.
5 . The system of claim 1 , wherein threshold is a voltage threshold, and wherein the circuitry of the electric field generator decreases the current when the voltage is within a range of 95% to 100% of the voltage threshold.
6 . The system of claim 1 , wherein the threshold is a voltage threshold, and wherein the circuitry of the electric field generator sets the current at the current threshold when the voltage is below the voltage threshold.
7 . The system of claim 1 , wherein the current threshold is determined based on a desired electric signal duration.
8 . The system of claim 1 , wherein the current of the electric signal of the electric field generator is operable to control the current independent (without) of a temperature reading from a temperature sensor.
9 . A method for generating TTFields, the method comprising:
determining a current threshold for a pad;
supplying, by circuitry of an electric field generator, an electric signal having a frequency in a range of 50 kHz to 1 MHz to a first port and a second port of the electric field generator;
monitoring, by the circuitry of the electric field generator, an impedance between the first port and the second port; and
controlling, by the circuitry of the electric field generator, a current of the electric signal to maintain the current within plus or minus 5% of a current threshold during a period of time in which the monitored impedance is below an impedance threshold.
10 . The method of claim 9 , further comprising:
determining a voltage threshold for the pad; and
monitoring, by a voltmeter of the circuitry, a voltage between the first port and the second port.
11 . The method of claim 10 , further comprising, upon the voltage reaching the voltage threshold, controlling, by the circuitry of the electric field generator, a voltage of the electric signal to maintain the voltage within a range of plus or minus 5% of the voltage threshold.
12 . The method of claim 10 , further comprising, upon the voltage reaching the voltage threshold, controlling, by the circuitry of the electric field generator, a voltage of the electric signal to maintain the voltage within a range of 95% to 100% of the voltage threshold.
13 . The method of claim 10 , wherein determining the voltage threshold for the pad includes determining the voltage threshold is within a range of 20 V to 240 V.
14 . The method of claim 10 , wherein controlling, by the circuitry of the electric field generator, the current of the electric signal further includes decreasing the current of the electric signal when the voltage is within a range of 95% to 100% of the voltage threshold.
15 . The method of claim 10 , wherein controlling, by the circuitry of the electric field generator, the current of the electric signal further includes controlling, by the circuitry of the electric field generator, the current at about the current threshold when the voltage between the first port and the second port is below the voltage threshold.
16 . The method of claim 9 , wherein determining the current threshold for the pad includes determining the current threshold is within a range of 1.5 to 5 Amperes.
17 . The method of claim 9 , wherein supplying, by circuitry of the electric field generator, the electric signal includes supplying, by circuitry of the electric field generator, the electric signal further comprising one or more of a sine waveform, modified sine waveform, square waveform, or triangle waveform.
18 . The method of claim 9 , wherein determining the current threshold for the pad further includes determining the current threshold for the pad based in part on a desired electric signal duration.
19 . The method of claim 9 , wherein controlling, by the circuitry of the electric field generator, the current of the electric signal is performed independent of a temperature reading from a temperature sensor.
20 . A system for generating TTFields, comprising:
a first port operable to receive a lead of a first pad;
a second port operable to receive a lead of a second pad;
an ammeter operable to determine a measured current of an electric signal supplied to the first port;
at least one meter selected from the group consisting of a voltmeter and an ohmmeter;
the voltmeter operable to determine a measured voltage between the first port and the second port; and
the ohmmeter operable to determine a measured impedance between the first port and the second port;
an electric field generator comprising circuitry operable to generate the electric signal having a frequency, a current, and a voltage, the frequency in a range of 50 kHz to 500 kHz, the circuitry operable to supply the electric signal to the first port and the second port, and to control the current to maintain the measured current within plus or minus 5% of a current threshold during a period of time in which at least one of the measured voltage and the measured impedance is below a threshold; and
a power supply operable to supply power to the electric field generator.