# US 2017/0281968 A1 · Scanning system

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- Number: US 2017/0281968 A1
- Document ID: US20170281968A1
- Status: Published application
- Kind: A1
- Application number: 15/492,132
- Filed: 2017-04-20
- Published: 2017-10-05
- Earliest claimed: 2014-02-20
- Assignees: Mevion Medical Systems, Inc.
- Applicants: Mevion Medical Systems, Inc.
- Inventors: Charles D. O'Neal, III; Adam C. Molzahn
- Web page: https://patentgrep.com/patent/US20170281968A1

## CPC

- A61N 5/103: {Treatment planning systems}
- A61N 5/1043: {Scanning the radiation beam, e.g. spot scanning or raster scanning}
- A61N 5/1048: {Monitoring, verifying, controlling systems and methods}
- A61N 5/1081: {Rotating beam systems with a specific mechanical construction, e.g. gantries}
- H05H 7/04: Magnet systems {, e.g. undulators, wigglers (free-electron laser H01S3/0903)}; Energisation thereof
- H05H 13/02: Synchrocyclotrons, i.e. frequency modulated cyclotrons
- H05H 13/04: Synchrotrons
- A61N 5/1049: {for verifying the position of the patient with respect to the radiation beam}
- A61N 5/1065: {Beam adjustment}
- A61N 5/1067: {in real time, i.e. during treatment}
- A61N 5/1071: {for verifying the dose delivered by the treatment plan}
- A61N 2005/1085: {characterised by the type of particles applied to the patient}
- A61N 2005/1087: {Ions; Protons}
- H05H 2007/002: {for modifying beam trajectory, e.g. gantries}
- H05H 2007/004: {for modifying beam energy, e.g. spread out Bragg peak devices}
- H05H 2007/048: {for modifying beam trajectory, e.g. gantry systems}
- A61N: ELECTROTHERAPY; MAGNETOTHERAPY; RADIATION THERAPY; ULTRASOUND THERAPY (measurement of bioelectric currents A61B; surgical instruments, devices or methods for transferring non-mechanical forms of energy to or from the body A61B18/00; anaesthetic apparatus in general A61M; incandescent lamps H01K; infrared radiators for heating H05B)
- H05H: PLASMA TECHNIQUE (apparatus or processes specially adapted for producing X-rays H05G2/00); PRODUCTION OF ACCELERATED ELECTRICALLY-CHARGED PARTICLES OR OF NEUTRONS; PRODUCTION OR ACCELERATION OF NEUTRAL MOLECULAR OR ATOMIC BEAMS

## Abstract

An example particle therapy system includes: a particle accelerator to output a beam of charged particles; and a scanning system to scan the beam across at least part of an irradiation target. An example scanning system includes: a scanning magnet to move the beam during scanning; and a control system (i) to control the scanning magnet to produce uninterrupted movement of the beam over at least part of a depth-wise layer of the irradiation target so as to deliver doses of charged particles to the irradiation target; and (ii) to determine, in synchronism with delivery of a dose, information identifying the dose actually delivered at different positions along the depth-wise layer.

## Claims

### Claim 1

A particle therapy system comprising:
a particle accelerator to output a beam of charged particles; and
a scanning system to scan the beam across at least part of an irradiation target, the scanning system comprising:
a scanning magnet to move the beam during scanning, where a position of the beam corresponds to a current of the scanning magnet; and
a control system (i) to control the current in order to produce uninterrupted movement of the beam across at least part of an irradiation target to deliver doses of charged particles, (ii) for positions at which the particle beam delivers dose, to store information identifying a location and an amount of dose delivered, (iii) to compare a cumulative dose delivered at each position to a target cumulative dose, and (iv) if the cumulative dose does not match the target cumulative dose at specific positions, control the current in order to move the beam so as to deliver additional dose to specific positions.

### Claim 2 (depends on 1)

The particle therapy system of claim 1, wherein the particle accelerator is configured to output pulses of charged particles in accordance with a radio frequency (RF) cycle, the pulses of charged particles forming the beam; and
wherein movement of the beam across the at least part of an irradiation target is not dependent upon the RF cycle.

### Claim 3 (depends on 2)

The particle therapy system of claim 2, wherein the control system is configured to measure the cumulative dose delivered at each position; and wherein measuring is substantially synchronous with the RF cycle.

### Claim 4 (depends on 2)

The particle therapy system of claim 2, wherein the control system is configured to measure the cumulative dose delivered at each position; and
wherein measuring is substantially synchronous with delivery of dose at each position.

### Claim 5 (depends on 1)

The particle therapy system of claim 1, wherein the information comprises an amount of dose delivered at each position and at least one of: a location of each position within the irradiation target or a magnet current corresponding to each position within the irradiation target.

### Claim 6 (depends on 1)

The particle therapy system of claim 1, wherein the location corresponds to three-dimensional coordinates within the irradiation target.

### Claim 7 (depends on 1)

The particle therapy system of claim 1, wherein the particle therapy system further comprises:
memory to store a treatment plan that identifies, for each position, a target cumulative dose of the particle beam, the treatment plan omitting information about individual doses delivered to individual positions during scanning.

### Claim 8 (depends on 1)

The particle therapy system of claim 1, wherein the scanning system further comprises:
a degrader to change an energy of the beam prior to output of the beam to the irradiation target, the degrader being down-beam of the scanning magnet relative to the particle accelerator;
wherein the control system is configured to control movement of at least part of the degrader into, or out of, a path of the beam in order to affect the energy of the beam and thereby set a layer of the irradiation target to which charged particles are to be delivered.

### Claim 9 (depends on 8)

The particle therapy system of claim 8, wherein the particle accelerator comprises an ion source to provide plasma from which pulses in the beam are extracted; and
wherein, during at least part of the movement of the degrader, the ion source is deactivated.

### Claim 10 (depends on 8)

The particle therapy system of claim 8, wherein the particle accelerator comprises:
an ion source to provide plasma from which pulses in the beam are extracted; and
a voltage source to provide a radio frequency (RF) voltage to a cavity to accelerate particles from the plasma, the cavity having a magnetic field for causing particles accelerated from the plasma column to move orbitally within the cavity; wherein, during at least part of the movement of the degrader, the voltage source is deactivated.

### Claim 11 (depends on 10)

The particle therapy system of claim 10, wherein, during the at least part of the movement of the degrader, the particle source is deactivated at a same time that the voltage source is deactivated.

### Claim 12 (depends on 1)

The particle therapy system of claim 1, wherein the particle accelerator is a variable-energy particle accelerator; and
wherein the control system is configured to set an energy level of the particle accelerator prior to scanning.

### Claim 13 (depends on 1)

The particle therapy system of claim 1, wherein the particle accelerator is a variable-energy particle accelerator; and
wherein the control system is configured to set an energy level of the particle accelerator during scanning.

### Claim 14 (depends on 1)

The particle therapy system of claim 1, wherein, for a position at which the particle beam delivers dose, each individual delivery of dose is a percentage of the total cumulative dose.

### Claim 15 (depends on 14)

The particle therapy system of claim 14, wherein the percentage is less than 100% of the total cumulative dose.

### Claim 16 (depends on 14)

The particle therapy system of claim 14, wherein the percentage is about 100% of the total cumulative dose.

### Claim 17 (depends on 1)

The particle therapy system of claim 1, wherein the scanning magnet has an air core.

### Claim 18 (depends on 1)

The particle therapy system of claim 1, wherein the scanning magnet has a ferromagnetic core.

### Claim 19

A particle therapy system comprising:
a particle accelerator to output a beam of charged particles; and
a scanning system to scan the beam across at least part of an irradiation target, the scanning system comprising:
a scanning magnet to move the beam during scanning; and
a control system (i) to control the scanning magnet to produce uninterrupted movement of the beam over at least part of a depth-wise layer of the irradiation target so as to deliver doses of charged particles to the irradiation target; and (ii) to determine, in synchronism with delivery of a dose, information identifying the dose actually delivered at different positions along the depth-wise layer.

### Claim 20 (depends on 19)

The particle therapy system of claim 19, wherein the particle accelerator is configured to output pulses of charged particles in accordance with a radio frequency (RF) cycle, the pulses of charged particles forming the beam; and
wherein movement of the beam is not dependent upon the RF cycle.

### Claim at position 21

21-27. (canceled)