Fast magnet method and apparatus used in conjunction with a charged particle cancer therapy system
First Claim
1. A method for rapidly redirecting positively charged particles in a charged particle cancer therapy system used to treat a tumor of a patient, comprising the steps of:
- accelerating the positively charged particles with a synchrotron;
extracting the positively charged particles through a first Lambertson extraction magnet to a fast switch magnet, said fast switch magnet comprising;
an inductor;
a first resistor, said first resistor comprising a resistance of at least one-tenth of an Ohm; and
a switch, said first resistor and said switch wired electrically in parallel, said inductor and said first resistor wired in series;
passing said positively charged particles through said fast switch magnet to a tumor treatment beamline at a first time, said fast switch magnet using a first current at the first time to yield a first charged particle directing magnetic field; and
redirecting the positively charged particles, at a second time, to a beam stop using said fast switch magnet, said step of redirecting comprising the step of;
opening said switch, said step of opening forcing the first current to pass through said first resistor resulting in a lower second current passing through said inductor, said second current at a second time resulting in a second charged particle directing magnetic field, said second charged particle magnetic field redirecting the positively charged particles to a beam stop, said first time and said second time differing by less than fifty microseconds.
1 Assignment
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Accused Products
Abstract
A fast magnet switching method and apparatus used to rapidly redirect cations, such as H+ or C6+, in a beam path, such as during or between treatment of individual volumes or voxels of a tumor of the patient, is described. Switching means include rapidly increasing or decreasing applied current to a coil about a magnet, which rapidly alters a magnetic field crossing the charged particle path and redirects a charged particle beam away from the patient, such as to a charged particle beam stop. Means to rapidly induce the current change include: (1) using a separate high voltage power supply and/or (2) opening a switch to redirect current through a resistor. In both cases, the rapid current change to the coil yields a rapid change the magnetic field and a corresponding rapid change in direction of the charged particles in the charged particle cancer therapy system.
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Citations
18 Claims
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1. A method for rapidly redirecting positively charged particles in a charged particle cancer therapy system used to treat a tumor of a patient, comprising the steps of:
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accelerating the positively charged particles with a synchrotron; extracting the positively charged particles through a first Lambertson extraction magnet to a fast switch magnet, said fast switch magnet comprising; an inductor; a first resistor, said first resistor comprising a resistance of at least one-tenth of an Ohm; and a switch, said first resistor and said switch wired electrically in parallel, said inductor and said first resistor wired in series; passing said positively charged particles through said fast switch magnet to a tumor treatment beamline at a first time, said fast switch magnet using a first current at the first time to yield a first charged particle directing magnetic field; and redirecting the positively charged particles, at a second time, to a beam stop using said fast switch magnet, said step of redirecting comprising the step of; opening said switch, said step of opening forcing the first current to pass through said first resistor resulting in a lower second current passing through said inductor, said second current at a second time resulting in a second charged particle directing magnetic field, said second charged particle magnetic field redirecting the positively charged particles to a beam stop, said first time and said second time differing by less than fifty microseconds. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. An apparatus for rapidly redirecting positively charged particles used to treat a tumor of a patient, comprising:
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a positively charged particle system, comprising; a synchrotron configured to accelerate the positively charged particles; a first Lambertson extraction magnet configured to extract the positively charged particles from said synchrotron to a fast switch magnet, said fast switch magnet comprising; an inductor; a first resistor, said first resistor comprising a resistance of at least one-tenth of an Ohm; and a switch, said first resistor and said switch wired electrically in parallel, said first resistor and said inductor wired in series; and a beam stop, said switch configured in a closed position at a first time, said fast switch magnet configured at the first time to pass said positively charged particles through said fast switch magnet to a tumor treatment beamline using a first current to yield a first charged particle directing magnetic field; and said switch configured in an open position at a second time, said fast switch magnet configured at the second time to force the first current to pass through said first resistor resulting in a lower second current passing through said inductor, said fast switch magnet at the second time configured to use the lower second current to yield a second charged particle directing magnetic field redirecting the positively charged particles to said beam stop, said first time and said second time differing by less than fifty microseconds. - View Dependent Claims (10, 11, 12)
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13. A method for rapidly redirecting positively charged particles in a charged particle cancer therapy system used to treat a tumor of a patient, comprising the steps of:
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accelerating the positively charged particles with a synchrotron; extracting the positively charged particles through a first Lambertson extraction magnet to a fast switch magnet, said fast switch magnet comprising an inductor powered by a first power supply and a second power supply; passing the positively charged particles through said fast switch magnet to a tumor treatment beamline at a first time, said fast switch magnet using a first voltage and a first current from said first power supply at the first time to yield a first charged particle directing magnetic field; and redirecting the positively charged particles to a beam stop using a pulse of greater than two hundred volts delivered to said fast switch magnet from said second power supply in less than twenty-five microseconds, said pulse of greater than two hundred volts driving the first current up to a second higher current in less than fifty microseconds, said second current at a second time resulting in a second charged particle directing magnetic field, said second charged particle magnetic field redirecting the positively charged particles to said beam stop, said first time and said second time differing by less than fifty microseconds. - View Dependent Claims (14, 15, 16, 17, 18)
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Specification