TECHNICAL FIELD

[0001] This disclosure relates generally to a particle therapy system that implements automated treatment.

BACKGROUND

[0002] Traditionally, particle therapy has been delivered isocentrically, where the approximate center of an irradiation target in a patient is positioned at a unique location, known as the isocenter, in a treatment space. A radiation source is arranged so that a central axis of the radiation source points to the isocenter. The radiation source is rotated around the isocenter, and the patient is also rotated around this same isocenter. By positioning the radiation source and the patient in this manner, the target may be irradiated from a number of projections, which correspond to different beam fields. As a result, a radiation dose to the target may be increased, while radiation to surrounding normal tissue may be reduced.

[0003] A dosimetrist working with a treatment planning system (TPS) may choose the projections. The TPS uses information about the patient's anatomy, the radiation source, and other available information to determine the planned dose for each chosen projection. The number of projections has typically been chosen so that the quality of the therapy is enhanced, without unduly burdening the radiation delivery process. Traditionally, treatment is administered for each projection by verifying the positioning of the patient and/or the radiation emitter prior to the first application of radiation. A radiation therapist enters the treatment room before the first projection and between each successive projection to reposition the patient and/or a radiation emitter as specified by the treatment plan.

[0004] This required manual intervention by a radiation therapist makes it difficult, and time-consuming, to implement a large number of projections. Also, the quality of the treatment can be affected in areas where projections may overlap. SUMMARY

[0005] An example particle therapy system comprises a particle beam output device to direct output of a particle beam; a treatment couch to support a patient containing an irradiation target, with the treatment couch being configured for movement; a movable device on which the particle beam output device is mounted for movement relative to the treatment couch; and a control system to provide automated control of at least one of the movable device or the treatment couch to position at least one of the particle beam or the irradiation target for treatment of the irradiation target with the particle beam and, following the treatment of the irradiation target with the particle beam, to provide automated control of at least one of the movable device or the treatment couch to reposition at least one of the particle beam or the irradiation target for additional treatment of the irradiation target with the particle beam. The example particle therapy system may include one or more of the following features, either alone or in combination.

[0006] The example particle therapy system may include a scanning system comprising components to move the particle beam relative to the irradiation target. The control system may be configured to provide automated control of one or more of the components to position the particle beam for the treatment of the irradiation target with the particle beam and, following the treatment of the irradiation target with the particle beam, to provide automated control of one or more of the components to reposition the particle beam for the additional treatment of the irradiation target with the particle beam. The one or more components may comprise one or more scanning magnets. The one or more components may comprise an energy degrader, with the energy degrader comprising one or more structures that are movable into, and out of, a path of the particle beam.

[0007] The control system may be configured to provide the automated control of at least one of the movable device or the treatment couch to treat a first part of the irradiation target using a first beam field of the particle beam and, following treatment of the first part of the irradiation target with the particle beam, to provide the automated control of at least one of the movable device or the treatment couch to reposition at least one of the particle beam or the irradiation target to treat a second part of the target using a second beam field of the particle beam.

[0008] The particle beam output device may comprise a particle accelerator. At an area between the first beam field and the second beam field, the particle beam for the first beam field and the particle beam for the second beam field may overlap at least partly. The control system may be configured to provide automated control of the particle accelerator to control intensities of the particle beam for the first beam field and the particle beam for the second beam field so that cumulative intensities at points of overlap between the particle beam for the first beam field and the particle beam for the second beam field reach a target beam intensity.

[0009] The particle beam output device may comprise a particle accelerator. At an area between the first beam field and the second beam field, the particle beam for the first beam field and the particle beam for the second beam field may overlap at least partly. The control system may be configured to provide automated control of the particle accelerator to control intensities of the particle beam for the first beam field and the particle beam for the second beam field so that cumulative intensities at points of overlap between the particle beam for the first beam field and the particle beam for the second beam field do not deviate from a target beam intensity by more than a defined amount.

[0010] The control system may be configured to control the treatment couch to implement translational motion. The control system may be configured to control the treatment couch to implement rotational motion.

[0011] The example particle therapy system may comprise an imaging system to capture images of the irradiation target during treatment. The control system may be configured to control the imaging system to capture one or more first images of the patient after positioning the at least one of the particle beam or the irradiation target for the treatment and before the treatment of the irradiation target with the particle beam, and the control system may be configured to control the imaging system to capture one or more second images of the patient after repositioning the at least one of the particle beam or the irradiation target for the additional treatment and before the additional treatment. The control system may be configured to use the first image to identify a first location of the irradiation target in a treatment space of the particle therapy system (e.g., in a proton center), and the control system may be configured to use the second image to identify a second location of the irradiation target in the treatment space.

[0012] The control system may be configured to receive a treatment plan from a treatment planning system, and to interpret the treatment plan to implement the control of at least one of the movable device or the treatment couch. The treatment plan may contain information identifying positions of at least one of the movable device or the treatment couch during treatment.

[0013] The control system may be configured to provide automated control of at least one of the movable device or the treatment couch independent of an isocenter defined in the particle therapy system. Automated control of at least one of the movable device or the treatment couch may be implemented absent human intervention.

[0014] The particle beam output device may comprise a particle accelerator. The control system may be configured to provide automated control of an operation of the particle accelerator to position at least one of the particle beam or the irradiation target for treatment of the irradiation target with the particle beam and, following the treatment of the irradiation target with the particle beam, to provide automated control of the operation of the particle accelerator to reposition at least one of the particle beam or the irradiation target for the additional treatment of the irradiation target with the particle beam.

[0015] The particle beam output device may comprise a synchrocyclotron having a superconducting electromagnetic structure. The particle beam output device may comprise a variable-energy synchrocyclotron having a superconducting electromagnetic structure. The particle beam output device may comprise a beam spreader. The beam spreader comprises one or more scanning magnets or one or more scattering foils

[0016] The example particle therapy system may comprise a configurable collimator between the particle beam output device and the patient. The

configurable collimator may comprise leaves that are controllable to define an edge to block a first part of the particle beam from reaching the patient while collimating a second part of the particle beam that passes to the patient. The configurable collimator may be controllable to trim an area as small as a single spot size of the particle beam.

[0017] The control system may be configured to provide automated control over movement of the particle beam output device to implement translational movement of the particle beam output device from a first location to a second location to position the particle beam for treatment of the irradiation target with the particle beam and, following the treatment of the irradiation target with the particle beam, to provide automated control over further movement of the particle beam output device to implement translational movement of the particle beam output device from the second location to a third location to reposition the particle beam for treatment of the irradiation target with the particle beam.

[0018] The control system may be configured to provide automated control over movement of the particle beam output device to pivot the particle beam output device from a first orientation to a second orientation to position the particle beam for treatment of the irradiation target with the particle beam and, following the treatment of the irradiation target with the particle beam, to provide automated control over further movement of the particle beam output device to pivot the particle beam output device from the second orientation to a third orientation to reposition the particle beam for treatment of the irradiation target with the particle beam.

[0019] The example particle therapy system may comprise a scanning system comprising components to move the particle beam relative to the irradiation target, with at least some of the components being mounted for movement towards, and away from, the irradiation target. The control system may be configured to provide automated control of the at least some of the components to position the particle beam for the treatment of the irradiation target with the particle beam and, following the treatment of the irradiation target with the particle beam, to provide automated control of the at least some of the components to reposition the particle beam for the additional treatment of the irradiation target with the particle beam. [0020] The example particle therapy system may comprise a carriage on which the at least some of the components are mounted, with the carriage being mounted to at least one track to enable movement along a path of the particle beam. The carriage may be controllable to move along the at least one track to control a size of a spot produced by the particle beam. The carriage may be controllable to move along the at least one track in coordination with movement of at least one of the movable device or the treatment couch.

[0021] The movable device may comprise a rotatable gantry. The movable device may comprise one or more robotic arms.

[0022] The example particle therapy system may comprise a scanning system comprising components to move the particle beam relative to the irradiation target, with the scanning components being mounted on a carriage that is movable along a beamline of the particle beam. The control system may be configured to provide automated control of the carriage to position the particle beam for the treatment of the irradiation target with the particle beam and, following the treatment of the irradiation target with the particle beam, to provide automated control of the carriage to reposition the particle beam for the additional treatment of the irradiation target with the particle beam.

[0023] An example method comprises supporting a patient containing an irradiation target on a treatment couch, with the treatment couch being configured for movement; mounting a particle beam output device on a movable device for movement relative to the treatment couch, with the particle beam output device for directing output of a particle beam to treat the irradiation target; providing automated control of at least one of the movable device or the treatment couch to position at least one of the particle beam or the irradiation target for treatment of the irradiation target with the particle beam and, following treatment of the irradiation target with the particle beam, providing automated control at least one of the movable device or the treatment couch to reposition at least one of the particle beam or the irradiation target for additional treatment of the irradiation target with the particle beam. The particle beam may be a proton beam. [0024] An example particle therapy system comprises a treatment couch to support a patient containing an irradiation target, with the treatment couch being configured for movement; a particle beam output device to direct output of a particle beam, with the particle beam output device being arranged for movement relative to the treatment couch; and a control system to control positioning of the particle beam output device and the treatment couch using degrees of freedom that exceed isocentric rotation of the particle beam output device and the treatment couch. The example particle therapy system may comprise one or more of the following features, either alone or in combination.

[0025] The particle beam output device may comprise scanning components to scan the particle beam relative to the irradiation target, with the scanning components comprising one or more scanning magnets. The control system may be configured to control a position of the particle beam by controlling operation of one or more of the scanning components The control system may be configured to control positioning of the particle beam output device and the treatment couch absent user intervention. The control system may be configured to control positioning of the particle beam output device and the treatment couch automatically for multiple beam fields. The particle beam output device may be controllable to move linearly between a first position and a second position. The particle beam output device may be controllable to pivot relative to the treatment couch. The particle beam output device may be controllable to rotate relative to the treatment couch. The particle beam output device may comprise a particle accelerator. The particle beam output device may be configured to produce a beam field of 30cm by 30cm or less.

[0026] An example particle therapy system comprises a treatment couch to support a patient containing an irradiation target, with the treatment couch being configured for movement; an apparatus to direct output of a particle beam; a movable device on which the apparatus is mounted to move the apparatus relative to the treatment couch, with the apparatus being mounted relative to the treatment couch to produce a beam field of 30cm by 30cm or less; and a control system to provide automated positioning of at least one of the apparatus or the treatment couch for treatment of a first part of the irradiation target with the particle beam and, following the treatment of the first part of the irradiation target with the particle beam, to provide automated repositioning at least one of the apparatus or the treatment couch for treatment of a second part of the irradiation target with the particle beam. The example particle therapy system may comprise one or more of the following features, either alone or in combination.

[0027] At least one of the automated positioning or the automated

repositioning processes may comprise translational movement. The apparatus may comprise a beam spreader to deliver the particle beam via a transmission channel. The apparatus may comprise a particle accelerator configured to generate the particle beam. The apparatus may be mounted to produce a beam field of 20cm by 20cm or less. The apparatus may comprise a synchrocyclotron having a weight that is within a range of 5 tons to 30 tons and that occupies a volume of less than 4.5 cubic meters.

[0028] The example particle therapy system may comprise a collision avoidance system to detect positions of one or more components of the particle therapy system and to provide information about positions to the control system. The control system may be configured to control operation of the one or more components based on the information. The control system may be configured to provide automated control of the particle beam to control intensities of the particle beam so that cumulative intensities at points of overlap between a particle beam for a first beam field and a particle beam for a second beam field remain within a range of a target beam intensity.

[0029] Two or more of the features described in this disclosure, including those described in this summary section, may be combined to form implementations not specifically described herein.

[0030] Control of the various systems described herein, or portions thereof, may be implemented via a computer program product that includes instructions that are stored on one or more non-transitory machine-readable storage media, and that are executable on one or more processing devices (e.g., microprocessor(s), application-specific integrated circuit(s), programmed logic such as field programmable gate array(s), or the like). The systems described herein, or portions thereof, may be implemented as an apparatus, method, or electronic system that may include one or more processing devices and computer memory to store executable instructions to implement control of the stated functions.

[0031] The details of one or more implementations are set forth in the accompanying drawings and the description below. Other features and advantages will be apparent from the description and drawings, and from the claims.

DESCRIPTION OF THE DRAWINGS

[0032] Fig. 1 is a cut-away, side view of components of an example synchrocyclotron that may be used in a particle therapy system.

[0033] Fig. 2 is a side view of example components that may be used to implement scanning in the particle therapy system.

[0034] Fig. 3 is a perspective view of example components that may be used to implement scanning in the particle therapy system.

[0035] Fig. 4 is a side view of an example scanning magnet that may be part of the scanning components.

[0036] Fig. 5 is a perspective view of an example scanning magnet that may be part of the scanning components.

[0037] Fig. 6 is a perspective view of an example range modulator, which is a type of energy degrader that may be part of the scanning components.

[0038] Fig. 7 is a perspective view showing an example of movement of plates that may be implemented in the range modulator.

[0039] Fig. 8 is a front view of components of an example implementation of a particle therapy system from the perspective of a treatment space.

[0040] Fig. 9 is a perspective view of components of another example implementation of a particle therapy system.

[0041] Fig. 10 is a conceptualized perspective view of a beam field.

[0042] Fig. 1 1 is a perspective view of components of the particle therapy system of Fig. 8 from the perspective of a treatment space. [0043] Fig. 12 is a diagram showing a particle beam hitting an irradiation target from different angles during intensity-modulated proton therapy (IMPT).

[0044] Fig. 13 is a flowchart showing an example process for automating treatment of a patient using a particle therapy system.

[0045] Fig. 14 is a system diagram depicting a control system, particle therapy system components, and a treatment planning system (TPS).

[0046] Fig. 15 is a block diagram depicting, conceptually, treatment across two different beam fields of a particle accelerator.

[0047] Fig. 16 is a block diagram depicting overlap of particle beams for two beam fields in an area of overlap of the two beam fields.

[0048] Like reference symbols in the various drawings indicate like elements.

DETAILED DESCRIPTION

[0049] Described herein are examples of particle therapy systems that are configured to automate treatment (e.g., delivery of particle beam) across sequential beam fields. Treatment furthermore is not limited to patient or accelerator movement relative to a single isocenter. Rather, in some implementations, components of the system, including those that affect beam position and patient position, may be computer-controlled to automate treatment at any appropriate point in an irradiation target, including across beam fields and without reference to an isocenter. Automating the treatment process, and reducing reliance on isocentric treatment, may provide for more treatment flexibility and support additional reductions in the size of the particle therapy system.

[0050] An example of a particle therapy system that is configurable to automate treatment in the manner described above is a proton or ion therapy system. In some implementations, the components of the proton therapy system that actually provide treatment, including the particle accelerator itself in some cases, are located in a single treatment room, called a proton center. In some implementations, the proton center is 30 feet (ft) by 30ft by 30ft (30 ft ³ ) or less in volume. In some implementations, the proton center is 37 feet (ft) by 32ft by 28ft or less in volume. In some implementations, a beam spreader (also referred to as a "spreader") is mounted for delivery of proton therapy to the patient. Examples of beam spreaders include, but are not limited to, one or more scanning magnets, examples of which are described herein, or one or more scattering foils. A

scattering foil scatters the particle beam to produce a dispersed beam for application to a target in the patient. A scanning magnet moves a more concentrated version of the particle beam in at least two dimensions across a target in the patient.

[0051] The beam field produced by the beam spreader is based, at least in part, on the distance between the beam spreader and an isocenter in the patient. In this regard, the beam field (also called the irradiation field) corresponds to a projection of radiation - here a particle beam - from the spreader. A beam field may be represented conceptually by a plane that defines the maximum extent or range that a projection of a particle beam can move in the X and Y directions relative to the irradiation target. The size (e.g., the area) of a beam field may be based on the distance between the beam spreader and an isocenter in the patient. In

implementations where the beam spreader includes one or more scanning magnets, the size of the beam field may also be based on the amount of current through the scanning magnets. That is, the more current that passes through the scanning magnets, the more the beam can be deflected, resulting in a larger beam field.

[0052] Because of the relatively small size of the proton center, the size of the beam field is limited. That is, because the proton center is relatively small, the distance between the beam spreader and the patient on a treatment couch is relatively short. In some implementations, the distance from the beam spreader to an isocenter in the patient may be 2 meters (m) or less, 1 .7m or less, 1 .5m, or less, 1 m or less, and so forth. As a result of this relatively short distance, the size of the beam field is also relatively small. For example, in some implementations, the size of the beam field may be 30 centimeters (cm) by 30cm or less, 20 cm by 20cm or less, and so forth. Also, large beam deflection angles are often discouraged for treatment, further limiting the size of the beam field.

[0053] The relatively small size of the beam field can affect treatment if the irradiation target (e.g., a tumor in a patient) exceeds the size of the beam field. For this reason, conventional proton therapy providers attempt to increase their field size as much as possible. By contrast, with the example compact system described herein - in particular one that delivers proton therapy in a single proton center - increasing the size of the beam field beyond a certain limit may be difficult in some examples due to physical limitations. Accordingly, the example systems described herein are configured to automatically treat an irradiation target using multiple beam fields. In some cases movement of the particle beam and the target are in degrees of freedom that exceed isocentric rotation of the particle accelerator or spreader and a treatment couch, making it possible to treat different beam fields automatically and, in some cases, absent user intervention.

[0054] The example particle therapy system includes a particle accelerator - in this example, a synchrocyclotron - mounted on a movable device. In some examples, the movable device is a gantry that enables the accelerator to be rotated at least part-way, and in some cases all the way, around a patient position to allow a particle beam from the synchrocyclotron to hit any arbitrary target in the patient. Any appropriate device, including a gantry, may be used to hold the particle accelerator and to move the particle accelerator in a rotational, translational, and/or pivotal motion relative to the patient. For example, the particle accelerator may be mounted to one or more tracks to enable motion relative to the patient. In another example, the particle accelerator may be mounted to one or more robotic arms to enable motion relative to the patient. In any case, the particle therapy system described herein is not limited to use with a gantry, to use with a rotational gantry, or to use with the example gantry configurations described herein. In some implementations, the beam spreader is mounted to the synchrocyclotron and is movable therewith. In some implementations, the beam spreader is mounted to the device - e.g., to the gantry - independent of the synchrocyclotron and is movable in the manner that the synchrocyclotron is described as being movable herein. The spreader is an example of a particle beam output device in that it directs the beam to the patient. Other examples of particle beam output devices are described herein including, but not limited to, the particle accelerator itself (or components thereof) which produces the particle beam and directs the output thereof. [0055] In some implementations, the example synchrocyclotron has a high magnetic field superconducting electromagnetic structure. In general, a

superconductor is an element or metallic alloy which, when cooled below a threshold temperature, loses most, if not all, electrical resistance. As a result, current flows through the superconductor substantially unimpeded. Superconducting coils, therefore, are capable of conducting much larger currents in their superconducting state than are ordinary wires of the same size. Because of the high amounts of current that superconducting coils are capable of conducting, magnets that employ superconducting coils are capable of generating high magnetic (B) fields for particle acceleration. Furthermore, because the bend radius of a charged particle having a given kinetic energy is reduced in direct proportion to an increase in the magnetic field applied to the charged particle, a high magnetic field superconducting electromagnetic structure enables the synchrocyclotron to be made compact, e.g., relatively small and light. More specifically, the higher the magnetic field used, the tighter the particle turn radius may be, thereby allowing for a larger numbers of turns to be made within a relatively small volume (that is, relative to larger, non- superconducting synchrocyclotrons). As a result, a desired particle energy - which increases with an increase in the number of turns - can be achieved using a synchrocyclotron having a relatively small size and weight. In some

implementations, the synchrocyclotron is configured to produce a particle beam having sufficient energy to reach any arbitrary target within the patient from any appropriate position in the proton center relative to the patient.

[0056] By way of example, in some implementations, a maximum magnetic field produced in the acceleration cavity of the synchrocyclotron (e.g., at the center of the cavity) may be between 4 Tesla (T) and 20T. In some implementations, the synchrocyclotron weighs less than 40 Tons. For example, the synchrocyclotron may have a weight that is within a range from 5 tons to 30 tons. In some

implementations, the synchrocyclotron occupies a volume of less than 4.5 cubic meters. For example, the synchrocyclotron may occupy a volume in a range from 0.7 cubic meters to 4.5 cubic meters. In some implementations, the

synchrocyclotron produces a proton or ion beam having an energy level of at least 150 MeV. For example, the synchrocyclotron may produce a proton or ion beam having an output energy level that is within a range from 150MeV to 300 MeV, e.g., 230 MeV. Different implementations of the synchrocyclotron may have different values or combinations of values for size, volume, and energy level, including values not stated. Advantageously, the compact nature of the synchrocyclotron described herein allows the treatment to be performed in one room, i.e., in the proton center.

[0057] In this regard, traditionally, particle accelerators, including

synchrocyclotrons, were considerably larger than the example compact accelerators described herein. By making the particle accelerator and the beamline (e.g., beam shaping) components compact, in some examples it is possible to enable operation of the system in closer patient proximity than has been possible with some traditional systems. For example, the compact size of the accelerator allows for mounting on the gantry (or other appropriate device), thereby reducing the cost and complexity of the whole system. But, in some examples, such a mounting may limit the space available for beamline (e.g., nozzle) components, forcing configuration of a relatively compact beamline. In some examples, this is one reason why an energy degrader as described herein is mounted in or on a nozzle that is relatively close to the patient, and in turn, why a collimator, also mounted in or on the nozzle, as described herein (which itself is compact) is used to keep beam edges sharp.

[0058] In some implementations, as described herein, the nozzle is mounted on an inner gantry that is within the sweep of the "outer" gantry holding the particle accelerator, that moves in synchronism with movement of the outer gantry, and that positions the nozzle to receive output of the accelerator on the outer gantry. In some implementations, the nozzle is mounted for movement on the inner gantry relative to the patient, e.g., along a C-shaped track. In some implementations, there may be no inner gantry, and all components described herein as being mounted to the inner gantry or to the nozzle are mounted to the outer gantry.

[0059] In some examples, the components mounted on the nozzle closest to the patient (e.g., a collimator and energy degrader) may present potential

interference, so those components may be made relatively small. But, the size of those components is related to the treatable field size. That is, these smaller components may also decrease the beam field size. In some cases, by enabling the particle therapy system to perform treatment using multiple beam fields, more compact beamline elements may be used. As a result, a smaller nozzle, which may be positioned in even closer proximity to the patient, may be used.

[0060] Fig. 1 shows a cross-section of components 10 of an example superconducting synchrocyclotron that may be used in a particle therapy system. In this example, components 10 include a superconducting magnet 1 1 . The

superconducting magnet includes superconducting coils 12 and 13. The

superconducting coils are formed, e.g., of multiple superconducting strands (e.g., four strands or six strands) wound around a center strand which may itself be superconducting or non-superconducting (e.g., copper). Each of the

superconducting coils 12, 13 is for conducting a current that generates a magnetic field (B). The resulting magnetic field is shaped by magnetic yokes 14, 15. In an example, a cryostat (not shown) uses liquid helium (He) to maintain each coil at superconducting temperatures, e.g., around 4° Kelvin (K). The magnetic yokes 14, 15 (or smaller magnetic pole pieces) are located inside the cryostat, and define the shape of a cavity 16 in which particles are accelerated. Magnetic shims (not shown) may pass through the magnetic yokes or pole pieces to change the shape and/or magnitude of the magnetic field in the cavity.

[0061] In some implementations, the particle accelerator includes a particle source 17 (e.g., a Penning Ion Gauge - PIG source) to provide an ionized plasma column to the cavity 16. Hydrogen gas, or a combination of hydrogen gas and a noble gas, is ionized to produce the plasma column. A voltage source provides a varying radio frequency (RF) voltage to cavity 16 to accelerate pulses of particles from the plasma column within the cavity. The magnetic field in the cavity is shaped to cause particles to move orbitally within the cavity. In some implementations, the maximum magnetic field produced by the superconducting coils may be within the range of 4 Tesla (T) to 20T, as explained herein. The example synchrocyclotron employs a magnetic field that is uniform in rotation angle and falls off in strength with increasing radius. In some implementations, such a field shape can be achieved regardless of the magnitude of the magnetic field. [0062] As noted, in an example, the particle accelerator is a synchrocyclotron. Accordingly, the RF voltage is swept across a range of frequencies to account for relativistic effects on the particles (e.g., increasing particle mass) when accelerating particles within the acceleration cavity. The magnetic field produced by running current through the superconducting coils, together with the shape of the cavity, causes particles accelerated from the plasma column to accelerate orbitally within the cavity and to increase in energy with an increasing number of turns.

[0063] In the example synchrocyclotron, a magnetic field regenerator (not shown) is positioned near the outside of the cavity (e.g., at an interior edge thereof) to adjust the existing magnetic field inside the cavity to thereby change locations, such as the pitch and angle, of successive orbits of the particles accelerated from the plasma column so that, eventually, the particles output to an extraction channel that passes through the cryostat. The regenerator may increase the magnetic field at a point in the cavity (e.g., it may produce a magnetic field "bump" of about 2 Tesla or so at an area of the cavity), thereby causing each successive orbit of particles at that point to proceed outwardly toward the entry point of an extraction channel until the particles reach the extraction channel. The extraction channel receives, from the cavity, particles that have been accelerated within the cavity, and outputs the received particles from the cavity in a pulsed particle beam. The extraction channel may contain magnets and other structures to direct the particle beam out of the particle accelerator and towards a scanning or scattering system.

[0064] As noted, the superconducting coils (called the main coils) can produce relatively high magnetic fields. In an example implementation, the maximum magnetic field generated by a main coil (e.g., at the center of the acceleration cavity) may be within a range of 4T to 20T or more. For example, the superconducting coils may be used in generating magnetic fields at, or that exceed, one or more of the following magnitudes: 4.0T, 4.1T, 4.2T, 4.3T, 4.4T, 4.5T, 4.6T, 4.7T, 4.8T, 4.9T, 5.0T, 5.1T, 5.2T, 5.3T, 5.4T, 5.5T, 5.6T, 5.7T, 5.8T, 5.9T, 6.0T, 6.1 T, 6.2T, 6.3T, 6.4T, 6.5T, 6.6T, 6.7T, 6.8T, 6.9T, 7.0T, 7.1 T, 7.2T, 7.3T, 7.4T, 7.5T, 7.6T, 7.7T, 7.8T, 7.9T, 8.0T, 8.1T, 8.2T, 8.3T, 8.4T, 8.5T, 8.6T, 8.7T, 8.8T, 8.9T, 9.0T, 9.1T, 9.2T, 9.3T, 9.4T, 9.5T, 9.6T, 9.7T, 9.8T, 9.9T, 10.0T, 10.1 T, 10.2T, 10.3T, 10.4T, 10.5T, 10.6T, 10.7T, 10.8T, 10.9T, HOT, 1 1 .1 T, 1 1 .2T, 1 1 .3T, 1 1 .4T, 1 1 .5T, 1 1.6T, 1 1 .7T, 1 1 .8T, 1 1 .9T, 12.0T, 12.1 T, 12.2T, 12.3T, 12.4T, 12.5T, 12.6T, 12.7T, 12.8T, 12.9T, 13.0T, 13.1T, 13.2T, 13.3T, 13.4T, 13.5T, 13.6T, 13.7T, 13.8T, 13.9T, 14.0T, 14.1 T, 14.2T, 14.3T, 14.4T, 14.5T, 14.6T, 14.7T, 14.8T, 14.9T, 15.0T, 15.1T, 15.2T, 15.3T, 15.4T, 15.5T, 15.6T, 15.7T, 15.8T, 15.9T, 16.0T, 16.1T, 16.2T, 16.3T, 16.4T, 16.5T, 16.6T, 16.7T, 16.8T, 16.9T, 17.0T, 17.1 T, 17.2T, 17.3T, 17.4T, 17.5T, 17.6T, 17.7T, 17.8T, 17.9T, 18.0T, 18.1T, 18.2T, 18.3T, 18.4T, 18.5T, 18.6T, 18.7T, 18.8T, 18.9T, 19.0T, 19.1T, 19.2T, 19.3T, 19.4T, 19.5T, 19.6T, 19.7T, 19.8T, 19.9T, 20.0T, 20.1 T, 20.2T, 20.3T, 20.4T, 20.5T, 20.6T, 20.7T, 20.8T, 20.9T, or more. Furthermore, the superconducting coils may be used in generating magnetic fields that are outside the range of 4T to 20T or that are within the range of 4T to 20T but that are not specifically listed herein.

[0065] In some implementations, such as the implementations shown in Fig. 1 , the relatively large ferromagnetic magnetic yokes 14, 15 act as returns for stray magnetic fields produced by the superconducting coils. In some systems, a magnetic shield (not shown) surrounds the yokes. The return yokes and the shield together act to reduce stray magnetic fields, thereby reducing the possibility that stray magnetic fields will adversely affect the operation of the particle accelerator.

[0066] In some implementations, the return yokes and shield may be replaced by, or augmented by, an active return system. An example active return system includes one or more active return coils that conduct current in a direction opposite to current through the main superconducting coils. In some example

implementations, there is an active return coil for each superconducting main coil, e.g., two active return coils - one for each main superconducting coil. Each active return coil may also be a superconducting coil that surrounds the outside of a corresponding main superconducting coil concentrically.

[0067] As noted, current passes through the active return coils in a direction that is opposite to the direction of current passing through the main coils. The current passing through the active return coils thus generates a magnetic field that is opposite in polarity to the magnetic field generated by the main coils. As a result, the magnetic field generated by an active return coil is able to reduce at least some of the relatively strong stray magnetic field resulting from a corresponding main coil.

[0068] By using an active return system, the relatively large ferromagnetic magnetic yokes 14, 15 can be replaced with magnetic pole pieces that are smaller and lighter. Accordingly, the size and weight of the synchrocyclotron can be reduced further without sacrificing performance. An example of an active return system that may be used is described in U.S. Patent No. 8,791 ,656 entitled "Active Return System", the contents of which are incorporated herein by reference.

[0069] At or near the output of the extraction channel of the particle accelerator, there may be one or more beam shaping elements, such as a scanning system and/or a scattering system. Components of these systems may be mounted on, or otherwise attached to, the nozzle for positioning relatively close to the patient during treatment. In some implementations, however, beam spreader(s) may be mounted closer to (e.g., on) the accelerator or the outer gantry itself (e.g., mounted to the outer gantry in the absence of an accelerator mounted there).

[0070] Referring to Fig. 2, in an example implementation, at the output of extraction channel 20 of synchrocyclotron 21 (which may have the configuration of Fig. 1 ) are example scanning components 22 that may be used to scan the particle beam across all or part of an irradiation target. Fig. 3 also shows examples of the components of Fig. 2. These include, but are not limited to, a scanning magnet(s) 24, an ion chamber 25, an energy degrader 26, and a configurable collimator 28. Other components that may be down-beam of the extraction channel are not shown in Figs. 2 or 3, including, e.g., one or more scatterers for changing beam spot size.

[0071] In an example operation, scanning magnet 24 is an example beam spreader, and is controllable in two dimensions (e.g., Cartesian XY dimensions) to position the particle beam in those two dimensions, and to move the particle beam across at least a part (e.g., a cross-section) of an irradiation target. Ion chamber 25 detects the dosage of the beam and feeds-back that information to a control system to adjust beam movement. Energy degrader 26 is controllable to move material (e.g., one or more individual plates) into, and out of, the path of the particle beam to change the energy of the particle beam and therefore the depth to which the particle beam will penetrate the irradiation target. In this way, the energy degrader can position the particle beam at a depth-wise layer of an irradiation target, e.g., to the layer. In some implementations, the energy degrader uses wedges or other types of structures instead of, or in addition to, plates. For example, energy degrader 26 may be controllable to move material (e.g., one or more individual wedges) into, and out of, the path of the particle beam to change the energy of the particle beam and therefore the depth to which the particle beam will penetrate the irradiation target.

[0072] In some implementations, there may be different energy degraders having different sizes, e.g., plates or wedges having different areas. In some implementations, the control system described herein may swap, in and out of the beam field, differently-sized energy degraders based on the beam field size.

[0073] Figs. 4 and 5 show views of an example scanning magnet 24. In this example implementation, scanning magnet 24 includes two coils 41 , which control particle beam movement in the X direction, and two coils 42, which control particle beam movement in the Y direction. Control is achieved, in some implementations, by varying current through one or both sets of coils to thereby vary the magnetic field(s) produced thereby. By varying the magnetic field(s) appropriately, the particle beam can be moved in the X and/or Y direction across the irradiation target. The scanning magnet(s) may be leveraged to control the location and/or direction of the particle beam in the automated treatment process described herein.

[0074] In some implementations, the scanning magnet is not movable physically relative to the particle accelerator. In some implementations, the scanning magnet may be movable physically relative to the particle accelerator (e.g., in addition to the movement provided by the gantry). In some implementations, the scanning magnet may be controllable to move the particle beam continuously so that there is uninterrupted motion of the particle beam over at least part of, and possibly all of, a layer of an irradiation target being scanned. In some implementations, the scanning magnets are controllable at intervals or specific times. In some

implementations, there may be two or more different scanning magnets to position the particle beam, and to control all or part movement of a particle beam in the X and/or Y directions during scanning. In some implementations, scanning magnet 24 may have an air core, a ferromagnetic (e.g., an iron) core, or a core that is a combination of air and ferromagnetic material.

[0075] Referring back to Fig. 2, a current sensor 27 may be connected to, or be otherwise associated with, scanning magnet 24. For example, the current sensor may be in communication with, but not connected to, the scanning magnet. In some implementations, the current sensor samples current applied to the magnet, which may include current to the coil(s) for controlling beam scanning in the X direction and/or current to the coil(s) for controlling beam scanning in the Y direction. The current sensor may sample current through the magnet at times that correspond to the occurrence of pulses in the particle beam or at a rate that exceeds the rate that the pulses occur in the particle beam. In the latter case, the samples, which identify the magnet current, are correlated to detection of the pulses by the ion chamber described below. For example, the times at which pulses are detected using the ion chamber may be correlated in time to samples from the current sensor, thereby identifying the current in the magnet coil(s) at the times of the pulses. Using the magnet current, it thus may be possible to determine the location on the irradiation target (e.g., on a depth-wise layer of the irradiation target) where each pulse, and thus dose of particles, was delivered. The location of the depth-wise layer may be determined based on the configuration of the energy degrader (e.g., the number of plates) in the beam path.

[0076] During operation, the magnitude(s) (e.g., value(s)) of the magnet current(s)) may be stored for each location at which a dose is delivered, along with the amount (e.g., intensity) of the dose. A computer system, which may be either on the accelerator or remote from the accelerator and which may include memory and one or more processing devices, may correlate the magnet current to coordinates within the radiation target, and those coordinates may be stored along with the amount of the dose. For example, the location may be identified by depth-wise layer number and Cartesian XY coordinates or by Cartesian XYZ coordinates (with the depth-wise layer corresponding to the Z coordinate). In some implementations, both the magnitude of the magnet current and the coordinate locations may be stored along with the dose at each location. The foregoing information may be stored in memory either on, or remote from, the accelerator. This information may be used during scanning to apply multiple doses of the same or of different amounts to the same locations to achieve target cumulative doses, including at areas of overlap between adjacent/sequential beam fields, as described herein.

[0077] In some implementations, ion chamber 25 detects dosage (e.g., one or more individual doses) applied by the particle beam to positions on an irradiation target by detecting the numbers of ion pairs created within a gas caused by incident radiation. The numbers of ion pairs correspond to the dose provided by the particle beam. That information is fed-back to the computer system and stored in memory along with the time that the dose is provided. This information may be correlated to, and stored in association with, the location at which the dose was provided and/or the magnitude of the magnet current at that time, as described above.

[0078] In some implementations, the scanning system is run open loop, in which case, by controlling the scanning magnet(s), the particle beam is moved freely and uninterrupted across an irradiation target so as to substantially cover the target with radiation. As the radiation is delivered, the dosimetry controlled by the particle therapy control system records (e.g., stores) the amount of the radiation per location and information corresponding to the location at which the radiation was delivered. The location at which the radiation was delivered may be recorded as coordinates or as one or more magnet current values, and the amount of the radiation that was delivered may be recorded as dosage in grays. Because the system is run open loop, the delivery of the radiation is not synchronized to the operation of the particle accelerator (e.g., to its radio frequency (RF) cycle). Locations on the target where insufficient dose has been deposited can be treated with the particle beam any appropriate number of times until a desired dosage is reached. Different treatments of the same location may be from the same beam angle (e.g., from the same projection/beam field) or from different beam angles (projections/beam fields) as is the case intensity-modulated proton therapy (IMPT) described herein.

[0079] Configurable collimator 28 may be located down-beam of the scanning magnets and down-beam of the energy degrader, as shown in Figs. 2 and 3. The configurable collimator may trim the particle beam on a spot-by-spot basis during movement of the particle beam during scanning. For example, the configurable collimator may include sets of leaves that face each other, and that are movable into and out of carriages to create an aperture shape. Parts of the particle beam that exceed the aperture shape are blocked, and do not pass to the patient. The parts of the beam that pass to the patient are at least partly collimated, thereby providing a beam with a relatively precise edge. In an example, each set of leaves in the configurable collimator is controllable to define an edge that is movable into a path of the particle beam such that a first part of the particle beam on a first side of the edge is blocked by the multiple leaves and such that a second part of the particle beam on a second side of the edge is not blocked by the multiple leaves. The leaves in each set are individually controllable during scanning to trim an area as small as a single spot, and can also be used to trim larger multi-spot areas.

[0080] Fig. 6 shows a range modulator 60, which is an example

implementation of energy degrader 26. In some implementations, range modulator 60 may be located down-beam of the scanning magnets between the configurable collimator and the patient. In some implementations, such as that shown in Fig. 6, the range modulator includes a series of plates 61 . The plates may be made of one or more of the following example materials: polycarbonate, carbon, beryllium or other material of low atomic number. Other materials, however, may be used in place of, or in addition to, these example materials.

[0081] One or more of the plates is movable into, or out of, the beam path to thereby affect the energy of the particle beam and, thus, the depth of penetration of the particle beam within the irradiation target. That is, each plate allows the beam to pass but, as a result of passing through the plate, the energy of the beam is decreased by an amount that is based on the geometry (e.g., thickness) and the composition (e.g., material) of the plate. In an example, the more plates that are moved into the path of the particle beam, the more energy that will be absorbed by the plates, and the less energy the particle beam will have. Conversely, the fewer plates that are moved into the path of the particle beam, the less energy that will be absorbed by the plates, and the more energy the particle beam will have. Higher energy particle beams typically penetrate deeper into the irradiation target than do lower energy particle beams. In this context, "higher" and "lower" are meant as relative terms, and do not have any specific numeric connotations.

[0082] Plates are moved physically into, and out of, the path of the particle beam. For example, as shown in Fig. 7, a plate 70 moves along the direction of arrow 72 between positions in the path of the particle beam 73 and outside the path of the particle beam. The plates are computer-controlled. Generally, the number of plates that are moved into the path of the particle beam corresponds to the depth at which scanning of an irradiation target is to take place. Thus, the particle beam can be positioned into the interior of a target by appropriate control of the plates.

[0083] By way of example, the irradiation target can be divided into cross- sections or depth-wise layers, each of which corresponds to an irradiation depth. One or more plates of the range modulator can be moved into, or out of, the beam path to the irradiation target in order to achieve the appropriate energy to irradiate each of these cross-sections or depth-wise layers of the irradiation target. The range modulator may be stationary relative to the particle beam during scanning of a part of (e.g., cross-section of) an irradiation target or the plates of the range modulator may move during scanning. For example, the particle beam may track movement of one or more plates into, or out of, the beam field (also called the irradiation field) during the scanning process.

[0084] Referring back Fig. 2, assembly 30, which includes, e.g., the ion chamber, the energy degrader, and the configurable collimator, may be mounted, or otherwise coupled, to carriage 23. In some implementations, carriage 23 is mounted to one or more tracks - in this example, to two tracks 29a, 29b - for movement relative to the irradiation target. In some examples, the carriage may be part of, or mounted to, the nozzle, thereby enabling some components of the scanning system to be moved towards, or away from, the patient. In some implementations, carriage 23 may be mounted using different mechanisms or in a different configuration for movement relative to the irradiation target. Movement may be along the beam line, e.g., along a path of the particle beam. This movement enables additional control over positioning of the particle beam - and thus an additional degree of freedom - to support treatment across, and irrespective of, beam fields and any isocenters. [0085] Movement also will allow these components to be moved away from a patient on the treatment couch to allow the nozzle and/or patient to be moved automatically for the next projection/ beam field to be treated. Then, the nozzle can be moved back toward the patient for the next beam field.

[0086] Moving the collimator and energy degrader towards, or away from, the irradiation target affects the distance that the particle beam travels through the air and, thus, the size of a spot of the particle beam in the irradiation target. That is, passage through air can cause the beam spot size to increase. Accordingly, moving the carriage away from the irradiation target increases the distance that the particle beam travels through the air, thus increasing the spot size. Conversely, moving the carriage towards the irradiation target decrease the distance that the particle beam travels through the air, thus decreasing the spot size. In some implementations, carriage 23 is controllable to move in coordination with movement of the gantry and/or the treatment couch as described herein to position the particle beam for treatment, and to implement treatment in close proximity to the patient.

[0087] Some components of the scanning system, including the energy degrader and the configurable collimator, may be mounted on, or coupled to, a nozzle 81 of the particle therapy system's inner gantry 80 (see Fig. 8), and may be controlled by a control system, such as one or more computing devices (see, e.g., Fig. 14) that also controls operation of other components of the particle therapy system. Fig. 9 shows another implementation of a particle therapy system having an inner gantry 90 with a nozzle 91 on which some components of the scanning system, including the energy degrader and the configurable collimator (but, in some cases, not the scanning magnet(s)), may be mounted. In both examples, the nozzle is movable along a track of the inner gantry (80 or 90) relative to the patient and the particle accelerator, and is extensible towards, and retractable away from, the patient, thereby also extending and retracting the components mounted thereon.

[0088] Operation of the range modulator may be coordinated with, and controlled with, operation of other scanning components, the particle accelerator, and the gantries described herein to implement automated particle therapy treatment and variations thereof. For example, the range modulator may be used to position the particle beam in a depth-wise (e.g., Cartesian Z) dimension relative to an irradiation target, and other scanning components, such as the beam spreader - e.g., the scanning magnet(s), may be used to position the particle beam in two other dimensions relative to the irradiation target that are orthogonal to the depth-wise dimension (e.g., the Cartesian X,Y dimensions). Positioning using the scanning components and other movable parts of the system supports automated, multiple- field treatment particle therapy that may or may not be isocentric. In cases where a variable-energy synchrocyclotron is used, control over beam energy, and thus beam depth-wise position, may be implemented in the accelerator itself.

[0089] As noted, the particle beam passes from the range modulator, through the configurable collimator, to the patient. Passage through air can cause the beam spot size to increase. The longer that the beam passes through air, the greater this spot size increase may be. Accordingly, in some implementations, it is

advantageous to reduce the maximum distance that the beam can pass through the air. As explained above, in some examples, the components mounted on the nozzle closest to the patient (e.g., a collimator and energy degrader) may reduce the amount that the beam passes through the air. However, in some examples, because of their proximity to the patient, those components may be made relatively small. The size of those components is related to the treatable field size. That is, these smaller components may result in a relatively smaller beam field size.

[0090] As described, the beam field (also called the irradiation field) is based on a projection of radiation from a beam spreader. A beam field may be represented conceptually by a plane that defines the maximum extent or range that a projection of a particle beam can move in the X and Y directions relative to the irradiation target. For example, Fig. 10 shows a beam field 100 in front of an irradiation target 101. The target is depicted in dashed lines to indicate that it is behind the beam field. Although a rectangular plane is shown, the beam field may have any appropriate shape. Due to physical system limitations, the particle beam produced by the synchrocyclotron is movable across, but not beyond, the borders of the beam field. As noted, reduced size of the nozzle enables the reduction in the air gap, but also may make the beam field smaller due to the presence of smaller components. [0091] In some situations, the beam field may be smaller than the irradiation target to be treated (which is not the case in Fig. 10, but see, e.g., Figs. 15 and 16 described below). Accordingly, in some examples, the processes described herein automate movement of components of the particle therapy system in order to treat the entire irradiation target using multiple beam fields without requiring manual accelerator reconfiguration, manual spreader reconfiguration, and/or manual patient repositioning. Treatment near the boundaries using two or more beam fields may be computer-controlled based on instructions received from a TPS using beam fields near the boundaries. Such treatment may also be independent of any isocenter location(s). Example implementations are described in more detail below.

[0092] Figs. 8 and 1 1 show parts an example of a particle therapy system 82 containing a particle accelerator mounted on a gantry - in this example, a

superconducting synchrocyclotron having a configuration described herein is used. In some implementations, the gantry is steel and has two legs (not shown) mounted for rotation on two respective bearings that lie on opposite sides of a patient. The gantry may include a steel truss, connected to each of its legs, that is long enough to span a treatment area in which the patient lies and that is attached at both ends to the rotating legs of the gantry. The particle accelerator may be supported by the steel truss. An example of a gantry configuration that may be used is described in U.S. Patent No. 7,728,31 1 entitled "Charged Particle Radiation Therapy", the contents of which are incorporated herein by reference.

[0093] Fig. 9 shows an example of the gantry configuration described in U.S. Patent No. 7,728,31 1 , and includes components of an alternative implementation of a particle therapy system that is controllable in the manner described herein to produce automated treatment. The example particle therapy system of Fig 9 includes an inner gantry 90 having a nozzle 91 , a treatment couch 92, and a particle accelerator 93 (e.g., a synchrocyclotron of the type described herein) mounted on an outer gantry 94 for rotation at least part-way around the patient to deliver radiation to target(s) in the patient. Treatment couch 92 is controllable and configured to rotate and to translate the patient in the manner described herein. [0094] In the example of Fig. 9, particle accelerator is also mounted to outer gantry 94 also to enable linear movement (e.g., translational movement) of the particle accelerator in the directions of arrow 95 along arms 96. Thus, the

accelerator is movable, relative to the treatment couch and thus the patient, from a first location along arms 96, to a second location along arms 96, to a third location along arms 96, and so forth in order to position the accelerator, and thus the beam, for treatment. This translational movement may be controlled by the control system described herein, and used as an additional degree of freedom for positioning the particle beam in the automated particle therapy system described herein. Although single-dimensional translational movement (along arrow 95) is shown in Fig. 9, the particle therapy system may be configured for two-dimensional translational movement, and/or three dimensional-translational movement as well (e.g., along the X, Y, and Z directions of a Cartesian coordinate system).

[0095] As also shown in Fig. 9, the particle accelerator 93 may be connected to a gimbal 99 for pivoting motion relative to the gantry. This pivoting motion may be used to position the accelerator, and thus the beam, for treatment. This pivoting movement may be controlled by the control system described herein, and may be used as one or more additional degrees of freedom for positioning the particle beam in the automated particle therapy system described herein. In some

implementations, pivoting may enable the accelerator to move from a first orientation, to a second orientation, to a third orientation, and so forth during automated treatment. The particle accelerator may be mounted to enable pivoting relative to the patient in one, two, and/or three dimensions.

[0096] As described herein, in some implementations, rather than mounting the entire particle accelerator to the outer gantry (or other device), the spreader alone may be mounted in lieu of, or in addition to, the accelerator, and the spreader alone or in combination with the accelerator may be moved relative to the irradiation target. In cases where the spreader is mounted alone, the spreader may be moved in the same way as the accelerators described herein, e.g., linearly (translation), rotationally, and/or pivotally. Control over beam positioning may be implemented as described herein by controlling movement of the spreader mounted thereon in the manner described herein.

[0097] The example particle therapy system implementations shown in Figs. 8 and 1 1 may also mount the particle accelerator so that the particle accelerator is capable of translational motion in one, two, and/or three dimensions relative to the patient. The example particle therapy system implementations shown in Figs. 8 and 1 1 may also mount the particle accelerator so that the particle accelerator is capable of pivoting relative to the patient in one, two, and/or three dimensions.

[0098] In the example of Figs. 8 and 1 1 , the patient is located on a treatment couch 84. In this example, treatment couch 84 includes a platform that supports the patient. The platform also may include one or more restraints (not shown) for holding the patient in place and for keeping the patient substantially immobile during movement of the couch and during treatment. The platform may, or may not, be padded and/or have a shape (e.g., an indentation) that corresponds to the shape of part of the patient. For example, prior to treatment, the patient may be placed in a mold that conforms to the contours of the back half of the patient, and the resulting molded structure may be incorporated into the platform of the treatment couch. A mold, such as this, may reduce patient motion during movement of the treatment couch including, but not limited to, during treatment.

[0099] The treatment couch may include a movement mechanism to move the treatment couch automatically from one position in the treatment space (e.g., the proton center where particle therapy treatment is performed) to another position in the treatment space. The different positions may be different rotational positions, different physical locations (e.g., a translational movement from one physical location to another physical location), or a combination of rotational and translational positions. For example, the movement mechanism may include a robotic arm 85 that is controllable to move the couch in six degrees of freedom.

[00100] Movement of the treatment couch is automated and occurs while the patient remains in place on the couch. For example, the treatment couch, with the patient thereon, may be moved between different treatment positions. In some implementations, the patient does not move off of the treatment couch during movement between treatment positions. For example, the patient may be situated on the treatment couch prior to treatment; the couch may be moved into a first position for treatment of a first part of the patient; the patient may be treated at the first position; the couch may be moved to a second, different position for treatment of a second, different part of the patient while the patient remains situated on the couch; the patient may be treated at the second position; the couch may be moved to a third, still different position for treatment of a third, still different part of the patient while the patient remains situated on the couch; and so forth until treatment ends. Any appropriate number of couch movements and treatments may be implemented, all while the patient remains on the treatment couch and, in some cases, without human intervention. The different "parts" of the patient to be treated may be, for example, different tumors, different areas of one tumor, or the same areas of one tumor, and may be treated from different angles as is the case during intensity-modulated proton therapy.("IMPT").

[00101] In this regard, during IMPT, the particle beam is projected at the irradiation target from different directions so that a percentage of the overall dose is delivered from each direction. As a result, the amount of dose delivered to volumes outside of the irradiation target can be reduced. For example, Fig. 12 shows a particle beam 120 applied to the irradiation target 121 from three different angles. In this example, dosage is cumulative, so 1/3 of the total dose may be applied from one angle; 1/3 of the total dose may be applied from another angle; and 1/3 of the total dose may be applied from yet another angle. That is, the particle beam may be scanned at angle 123 across a portion of a beam field in a plane angled relative to horizontal 128 to apply 1/3 of the dose; the particle beam may be scanned at angle 124 across a portion of a beam field in another plane angled relative to horizontal 128 to apply 1/3 of the dose; and the particle beam may be scanned at angle 125 across a portion of a beam field in still another plane angled relative to horizontal 128 to apply 1/3 of the dose. As a result, the amount of radiation applied to surrounding tissue 127 is spread out at the appropriate angles, thereby reducing the chances that surrounding tissue will be exposed to harmful amounts of radiation. Even though only three are shown, any appropriate number of angles and

appropriate dosage per angle may be employed.

[00102] Referring to Figs. 8, 9, and 1 1 , the inner gantry may be configured to move relative to the treatment couch to direct output of the beam toward the patient. In these examples, the inner gantry is C-shaped, and its movement coincides with movement of the "outer" gantry, on which the synchrocyclotron is mounted. As explained, the inner gantry includes a nozzle, on which one or more beamline components (e.g., the range modulator and configurable collimator) are mounted to shape and otherwise adjust the beam. In some implementations, the inner gantry supports sub-millimeter beam positioning. In some implementations, there is no inner gantry, and all components described herein as being mounted on the inner gantry may be mounted to the accelerator or to the outer gantry.

[00103] In some implementations, some or all movement of the treatment couch occurs while the patient remains in place on the couch. As explained, the treatment couch, with the patient thereon, may be moved automatically between treatment positions. In some implementations, the particle therapy system captures images of the patient between treatments in order to direct the treatment to the appropriate locations within the patient. In some implementations, these images are captured while the patient is on the treatment couch. For example, referring to the process of Fig. 13, the patient may be situated (130) on the treatment couch prior to treatment; the couch may be moved (131 ) into a first position for treatment of the irradiation target or a portion of the irradiation target within the patient with a first beam field; images of the patient at the first position may be captured (132) while the patient is on the treatment couch; and the patient may be treated (133) at the first position based on the images. If additional treatments are to be performed (134), the couch may be moved to a second, different position for treatment of the irradiation target or a portion thereof with a second beam field while the patient remains situated on the couch; images of the patient at the second position may be captured while the patient is on the treatment couch; the patient may be treated at the second position based on the captured images; the couch may be moved to a third, still different position for treatment of the irradiation target or a portion thereof with a third beam field while the patient remains situated on the couch; images of the patient at the third position may be captured while the patient is on the treatment couch; the patient may be treated at the third position based on the captured images; and so forth until treatment ends. In some implementations, a sequencing that is different than that presented above may be employed or different patient position tracking techniques than those described may be used. In some

implementations, imaging following each treatment is not required.

[00104] In some implementations, the particle therapy system is configured to determine the location of an irradiation target, such as a tumor. The initial location and mapping of the irradiation target (e.g., the tumor) may be obtained in a pre- treatment imaging operation, which may occur inside or outside the proton center. In some implementations, the patient may remain on the couch from initial imaging through treatment, including repositioning during treatment, as explained with respect to Fig. 13. Furthermore, in some implementations, the entire process, from initial imaging to final treatment, is automated, eliminating or, at least, reducing the need for human intervention.

[00105] In some implementations, the pre-treatment imaging operation may be performed using an imaging system, such as a three-dimensional (3D) imaging system. In some implementations, the 3D imaging system is a computed

tomography (CT) system; however, in other implementations, different types of imaging systems may be used instead of, or in addition to, a CT system. In operation, images may be captured at different points in time in order to enable tracking of movement of a fiducial due, e.g., to patient movement, such as breathing or the like. In this context, a fiducial includes a structure that is internal or external to the patient, that can be identified in an image captured by the imaging system, and that can be used to determine the location of an irradiation target within the patient.

[00106] In the CT example, the image may include internal anatomical structures, such as organs, tumors, and bones, any of which may be an irradiation target (or fiducial, as described below). The imaging system captures one or more images of the patient, or a selected part of the patient, typically the part(s) of the patient where proton therapy is to be applied. In some implementations, the treatment couch may include one or more fiducials arranged thereon. Examples of fiducials may include, but are not limited to, metal or other material that shows-up on images, such as CT images. The fiducials may be arranged at areas around the patient, e.g., at and/or around parts of the patient where proton therapy is to be applied. In some implementations, at least three fiducials are arranged relative to the patient to enable use of a triangulation process to locate the irradiation target in both the CT image and the treatment space. In some implementations, CT images may be used to identify structural elements of a person's anatomy, such as teeth, bone, or the like, and to designate those structural elements as fiducials. In some implementations, fiducials may be a combination of any two or more of the foregoing, e.g., anatomical structures and/or structural elements secured to the treatment couch, to the patient, to a frame, or the like.

[00107] In the CT example, images are 3D so that, either alone or in

combination, the images provide information about the location of the fiducials and the location of the irradiation target (e.g., the tumor) in 3D. This information is indicative of the relative positions of the fiducials and the irradiation target, and the angles and distances between individual fiducials and between individual fiducials and the radiation target. In some implementations, the position information is obtained by identifying the fiducials and the irradiation target in the 3D image(s), and by analyzing the image(s) to determine the locations of the fiducials and the size, shape, and location of the irradiation target based on the locations of the fiducials (and, in some cases, based on the size and/or shape of the fiducials). This information may be stored in computer memory and used during treatment in order to identify the location of the target in the treatment space (the "real world").

[00108] Following initial imaging using the CT system, the patient may be moved to the treatment position. The treatment couch may move automatically while the patient is on the couch, or the patient may move to a new treatment couch. The location to which the treatment is to be applied is determined, in part, based upon the 3D image(s) captured by the CT system (in this example).

[00109] Referring to Fig. 8, one or more treatment site (proton center) imaging systems 86, such as an X-ray system, are controlled to capture one or more images at the treatment position in the treatment space. This treatment site imaging system may be used alone, or in combination with, a computing system to detect locations of the fiducials, and thus the irradiation target, in the treatment space. The locations of the fiducials are detected relative to one or more reference points in a coordinate system that defines the treatment space. In other words, the treatment space (e.g., the proton center) may be defined within a 3D coordinate system, and the locations of the fiducials may be identified by coordinates in that 3D coordinate system.

[00110] For example, the images from the treatment site imaging system (e.g., X-ray images) may be analyzed to determine the locations of the fiducials in a 3D XYZ Cartesian coordinate system that defines the treatment space. One or more images of the fiducials taken by the imaging system may be analyzed to identify where, in the 3D coordinate system of the treatment space, the fiducials are located. The resulting coordinates of the fiducials in that coordinate system may be stored, e.g., in computer memory on a computer system (not shown).

[00111] The locations of the fiducials in the 3D coordinate system of the treatment space are aligned to the locations of the fiducials in the 3D CT image(s). This may be done automatically by a computer system using a virtual simulation (e.g., rendering) of the treatment space. For example, the actual locations of the fiducials may be identified in the simulation, and the fiducials from the 3D CT image, along with other structures from the CT image, may be placed at corresponding points in the simulation. By placing the fiducials and other structures from the CT image in the 3D coordinate system of the treatment space, it is possible to identify the location of the irradiation target in that same space.

[00112] More specifically, the locations of the fiducials in the treatment space (e.g., the 3D coordinate system of the treatment space) are known, and the fiducials and structures, including the irradiation target, from the 3D CT image are mapped into the 3D coordinate system in the simulation. As part of the mapping, the fiducials from the CT image are aligned to the locations of the fiducials in the 3D coordinate system of the treatment space. Furthermore, the location of the irradiation target relative to the fiducials is known from the 3D CT image. For example, the distances and angles of the irradiation target relative to each fiducial are known. Given this information, the location and orientation of the irradiation target in the 3D coordinate system of the treatment space can be determined. This information is used to direct the particle beam to the irradiation target.

[00113] The foregoing process of locating (e.g., by X-ray) fiducials in the 3D coordinate system of the treatment space and correlating those fiducials to those found in the original CT image(s) may be automated and repeated each time the treatment couch supporting the patient is moved within the treatment space. In some implementations, after the images are taken for a position, because the process may be under computer control and patient positioning will be monitored to confirm that the patient has not moved, new images may not need to be captured at each new position to which the patient is moved. For example, accuracy of the treatment couch motion and immobilization of the patient may be relied upon to determine positions at new locations.

[00114] In this regard, the treatment couch may be moved automatically between treatment positions in order to treat different parts of the patient or to treat the patient from different angles, as in the case in IMPT. In some implementations, for each new position, a new image is captured, e.g., by an X-ray system, and is analyzed relative to the original CT image(s). The resulting position information identifies the location to be treated in the real world space, e.g., in the 3D coordinate system of the treatment space (e.g., the proton center). Knowing the location of the target, various components of the proton therapy system can be controlled to position the particle beam and/or the patient to provide appropriate treatment to appropriate target areas. In some example implementations, the various

components can be controlled to perform treatment with respect to any part of the target, and are not constrained to treatment relative to a defined isocenter.

[00115] In some implementations, the treatment site imaging system(s) alone may be used to identify the location of the irradiation target, with or without fiducials, and to track movement of the target following repositioning or other event.

[00116] Referring to Fig. 8, a collision avoidance system 88 may be controlled to identify the locations of various components of the particle therapy system, the patient and other structures in the treatment space, and to feed-back that information to the control system. More specifically, as described, in some implementations, the system is automated in that the beam spreader, the particle accelerator and its components, and the treatment couch are controlled to move, automatically, to different positions between applications of the particle beam. This automatic movement is advantageous in that it eliminates the need for a human to reconfigure the system (e.g., the nozzle, accelerator, and/or couch positions) between applications of particle beam. However, automation will typically require coordination among the various moving parts of the system, which may be

implemented by the control systems described here. For safety purposes, the collision avoidance system 88 tracks motion of system components, such as the treatment couch, the particle accelerator, the carriage containing the energy degrader and collimator, and so forth, and relays information about that motion to the control system. If the control system detects, based on that information, that there is a possibility of a collision between two components or between a component and the patient or other structures/objects in the treatment space, the control system intervenes and changes the trajectory of one or more of the components or halts the motion of one or more of the components.

[00117] In some implementations, the collision avoidance system 88 may be implemented using one or more sensors, a 3D imaging system, laser positioning, sonar, ultrasound, or any appropriate combination thereof. In some

implementations, other types of device detection systems may be used instead of, or in addition to, those described herein to implement collision avoidance.

[00118] In addition to the foregoing, the nozzle - which in some

implementations is located on the inner gantry - may be retracted away from the patient or other object in the treatment space in order to avoid collisions. In some examples, this aspect of nozzle operation may be controlled by the control system based on feedback information from the collision avoidance system.

[00119] Referring to Fig. 14, control of the particle therapy system components 141 may include, but is not limited to, operation of and positioning and repositioning of the spreader - e.g., the one or more scanning magnets or scattering foils, the outer and inner gantries, the treatment couch, the nozzle, the beam shaping elements - e.g., the energy degrader and collimator, the carriage on which the beam shaping elements are mounted, the imaging systems (including, but not limited to, systems for beam targeting), the collision avoidance system, and the

synchrocyclotron (both translation positioning and orientation positioning). Such control may implemented by a control system 140. Control system 140 may include one or more computer systems as described herein and/or other control electronics. For example, control of the particle therapy system and its various components may be implemented using hardware or a combination of hardware and software. For example, a system like the ones described herein may include various controllers and/or processing devices located at various points, e.g., a controller or other type of processing device may be embedded in each controllable device or system. A central computer may coordinate operation among the various controllers or other types of processing devices. The central computer, controllers, and/or processing devices may execute various software routines to effect control and coordination of testing, calibration, and particle therapy treatment.

[00120] To automate treatment in the manner described, an example TPS 142, which is in communication with the particle therapy system, defines a treatment session by sets of positions of a patient and positions of components of a particle (e.g., proton) output device. In an example, each set of positions may include, at least, a unique combination of a position of the treatment couch and a position of the output device, where the position of the output device is defined, at least in part, based on a position of the outer gantry (e.g., [couch position, beam position]). For each element in this set, a pattern of radiation is to be administered to at least a portion of an irradiation target. The motion of the patient is not limited to rotations, but also includes at least one translation, enabling the system to improve treatment of linear targets. The TPS may be implemented on one or more computer systems of the type described herein and/or other control electronics, and may be configured to communicate with control system 140 using any appropriate wired or wireless media. In some implementations, this allows a particle therapy system having a small beam field to treat large irradiation targets effectively and efficiently. [00121] As explained above, the particle therapy system may have a relatively small beam field size, which is dictated, at least in part, by the distance between the particle/proton output device (for example, the spreader, the accelerator, or some other device capable of beam delivery) and the patient. In some implementations, the particle therapy system has a spreader-to-patient isocenter distance in a range of 1 m to 2m (e.g., 1.5m or less than 2m) and a beam field area that is about 20cm by 20cm or less. In some implementations, the particle therapy system has a source-to-axis distance in a range of 1 m to 2m (e.g., 1.5m or less than 2m) and a beam field area that is about 30cm by 30cm or less. Other values of the spreader- to-patient isocenter distance and beam field area also may be implemented.

[00122] In example implementations described herein, the spots size is dominated by a distance between the energy degrader, which dominates the beam line's contribution to beam divergence, and the patient. That is a distance that it may be advantageous to reduce, and why it may be beneficial to reduce the size of the components mounted to the nozzle. In some implementations, it is possible to perform downstream treatment of a defined isocenter.

[00123] Fig. 15 shows an example of a beam field 150 relative to an irradiation target 159, which may be a tumor in the patient. Thus, in this example, the synchrocyclotron 151 does not have a beam field that is large enough to treat the entire irradiation target. Traditionally, particle beam 155 would be scanned across this first beam field 150 for a first treatment and then a radiation therapist would enter the treatment room and reposition the nozzle or other output device and/or the patient to scan the particle beam 155 across the second beam field 152 at a next isocenter. This process was repeated to treat the entire target, as described above.

[00124] The particle therapy system described herein, however, does not require a therapist to reposition the patient or the nozzle between treatments, at least in some cases (that is, the system does not prohibit therapist intervention, if necessary). For example, a computer system (e.g., control electronics) that controls the particle therapy system receives a treatment plan for the irradiation target. The treatment plan automates treatment using different beam fields (e.g., 150, 152). In some examples, the treatment plan also does not rely on isocenter locations for patient or beam positioning, although in other examples, isocenters may be used.

[00125] In some implementations, operation of the particle therapy system may be controlled with a button located outside of the proton center. For example, a single press of the button could begin treatment and, in some examples, the treatment may continue uninterrupted, and without requiring human intervention, across and using multiple beam fields until an entire treatment area has been treated. In some example implementations, the entire treatment of an irradiation target may be delivered in less than about five minutes which is enabled by the automated (e.g., without human intervention) beam field sequencing described herein. In some implementations, human intervention may be included in the treatment process. For example, a human may press the button (or buttons) located inside or outside of the proton center to begin application of radiation, and thus a new treatment, each time various components of the particle therapy system are automatically positioned following a preceding treatment.

[00126] In operation, the computer system interprets and/or executes instructions from the TPS to control one or more components of the particle therapy system in order to position the patient (and thus the target) and the particle beam at appropriate locations for treatment. Examples of components of the particle therapy system that may be controlled automatically to position the patient and the particle beam to implement automated treatment may include, but are not necessarily limited to one or more of the following: the spreader and/or the synchrocyclotron (including translational or pivotal movement), the outer gantry (for rotation of the

synchrocyclotron and/or the spreader alone or in combination), the inner gantry (for positioning of the nozzle, including the beam shaping elements), the nozzle, the scanning magnet(s) or the scattering foil(s) (e.g., the beam spreader), the range modulator, the configurable collimator, the carriage to which the components of the nozzle are coupled, the treatment couch, the treatment site imaging system(s), and the collision avoidance system.

[00127] In addition, components of the synchrocyclotron may support treatment by controlling, e.g., by varying, the intensity of the particle beam during treatment. Variations in intensity may be achieved by controlling the number of particles per pulse of the particle beam. For example, the RF voltage sweep may be altered, or the operation of the ion source may be controlled, to select a desired intensity of the particle beam. Examples of processes that may be used by the synchrocyclotron described herein to control the intensity of the output particle beam are described in U.S. Patent Publication No. 2014/0094638 entitled "Controlling Intensity of a Particle Beam", the contents of which are incorporated herein by reference.

[00128] Using appropriate command and control protocols, in an example, the computer system 140 that directs operation of the particle therapy system controls operation, including positioning, of one or more of the spreader and/or the

synchrocyclotron (including translational or pivotal movement), the outer gantry (for rotation of the synchrocyclotron and/or the spreader alone or in combination), the nozzle, the scanning magnet(s) or the scattering foil(s) (e.g., the beam spreader), the range modulator, the configurable collimator, and the carriage to which the components of the nozzle are coupled to position the particle beam at an

appropriate location in the treatment space (e.g., the proton center) to administer radiation dosage to a target. Using appropriate command and control protocols, in an example, the computer system that directs operation of the particle therapy system controls operation of the treatment couch to position the patient, and thus the irradiation target, at an appropriate location in the treatment space to administer radiation dosage via the particle beam. Using appropriate command and control protocols, in an example, the computer system that directs operation of the particle therapy system controls operation of the synchrocyclotron to produce a particle beam having characteristics (e.g., intensity, energy, etc.) that are appropriate to administer required doses of radiation at locations defined in a treatment plan.

Instructions in the TPS state where and when radiation is to be applied, and define the positions of the various system components needed to provide the appropriate radiation. Using appropriate command and control protocols, in an example, the computer system also directs operation of the site imaging system and the collision avoidance system to implement automated treatment. [00129] Control over operation, including movement, of the spreader and/or the synchrocyclotron (including translational or pivotal movement), the outer gantry (for rotation of the synchrocyclotron and/or the spreader alone or in combination), the nozzle, the scanning magnet(s) or the scattering foil(s) (e.g., the beam spreader), the range modulator, the configurable collimator, the carriage to which the

components of the nozzle are coupled, and the treatment couch enables positioning the patient and the beam with multiple degrees of freedom that exceed simple isocentric rotations of the particle accelerator and the treatment couch or that exceed simple isocentric rotations of the spreader and the treatment couch. For example, in some implementations, rotation of the gantry provides one degree of freedom; movement of, or produced by, the scanning magnet(s) provides two degrees of freedom; movement of, or produced by, the range modulator provides one degree of freedom; and movement of the treatment couch provides six degrees of freedom, resulting in ten degrees of freedom. In some implementations, as described herein, the spreader and/or the particle accelerator (and, thus, the particle beam) may be translatable (e.g., movable in a linear motion) in one, two, and/or three dimensions for additional degree(s) of freedom of movement. As explained herein, in some implementations, the spreader and/or the particle accelerator (and, thus, the particle beam) may be pivotable or be mounted to a gimbal (e.g., a pivoted support that allows the rotation of an object about a single axis), resulting in one or more additional degree(s) of freedom of movement. Control over movement of the carriage may provide an additional degree of freedom.

[00130] As noted, the computer system controls operation, including

movement, of one or more of the spreader and/or the synchrocyclotron (including translational or pivotal movement), the outer gantry (for rotation of the

synchrocyclotron and/or the spreader alone or in combination), the nozzle, the scanning magnet(s) or the scattering foil(s) (e.g., the beam spreader), the range modulator, the configurable collimator, the carriage to which the components of the nozzle are coupled, and the treatment couch to position the particle beam and/or the patient for treatment, and to automatically reposition the particle beam and/or the patient for additional, successive treatments. When that the patient is moved, the computer system may instruct, and control, the site imaging system(s) automatically to capture an image of the patient (and thus the irradiation target) at a new position, and to determine the location of the irradiation target at the new position. Movement may include pivoting, rotation and/or translation. For example, changes in patient orientation may be relevant to IMPT treatments. Determining the location of the irradiation target at the new position may be implemented as described above or using other appropriate methods. Thereafter, treatment may proceed. During movement, the collision avoidance system operates as described above to reduce the possibility of collision among components of the system. The collision avoidance system acts to reduce the possibility of collision among objects in the treatment space that are part of, and not part of, the system.

[00131] In some implementations, if it is determined, through patient

monitoring, that the patient has not moved between treatment positions, then there may be no need to perform re-imaging or other processes to locate the irradiation target after each movement.

[00132] Movement of the patient couch may be in concert with treatment that occurs across beam fields. For example, in some implementations, the TPS may instruct automated treatment of a first beam field, followed by treatment of a second beam field, followed by treatment of a third beam field, and so forth. To generalize further, in some implementations, the moving parts of the system may be configured for each beam spot, making the beam delivery effectively fieldless in that the delivery is not constrained by field. Moreover, the particle therapy system may be controlled to move the particle beam back-and-forth between the same two beam fields multiple times, if necessary, independent of any system isocenters, if defined. In this example, as described elsewhere herein, movement of all components and control over imaging and sensors is automated, allowing the entire treatment process to be performed without a therapist manually repositioning the patient or the spreader and/or the particle accelerator.

[00133] Referring to Fig. 16, different, adjacent beam fields 161 , 162 may overlap at an area 166. The adjacent beam fields may be for treatment of target 170. This overlap area may be subjected to particle beams from different beam fields - in this example, particle beam 164 for beam field 162 and particle beam 165 for beam field 161 . Because particle - and, in particular, proton - radiation is cumulative, if no corrective action is taken, beam overlap can cause too much radiation to be deposited in the areas of overlap. Likewise, if the areas of overlap are avoided, or the beams are not applied there correctly, then insufficient radiation for treatment may be applied (e.g., a gap). Accordingly, the example particle therapy system may be controlled to vary the intensity of the particle beam in areas of overlap, thereby allowing for beam overlap, while still ensuring that appropriate dosage is applied to areas of overlap between adjacent beam fields.

[00134] More specifically, in some implementations, the TPS may provide instructions in the treatment plan specifying the intensity of the beam at areas of overlap between adjacent beam fields. For example in an overlap area, particle beams from different beam fields may have lower intensities (e.g., a lesser concentration of protons) than particle beams in the beam fields, but outside the overlap area. The intensities of the beam may decrease further from the center of the beam field in a feathering effect. In this example, beam intensities are controlled so that the beams produce, in an overlap area, such as area 166, a uniform distribution of particles across the different beam fields. In some implementations, this uniform distribution is the same as the distribution in non-overlapping areas of one or both of the beam fields; however, because the distribution may vary even within a single beam field, this need not be the case. Specifically, the control system is configured to provide automated control of the particle accelerator to control intensities of the particle beams for the different beam fields so that cumulative intensities at areas of overlap between two or more particle beams reach a target beam intensity or are within a predefined range of the target intensity, and do not deviate from (e.g., exceed or fall below) the target intensity by more than a predefined amount.

[00135] In some examples, a certain amount of overlap, as shown in Fig. 16, is contemplated and accounted for by appropriate control over the particle beam, including variations in beam intensities at or near areas of overlap between adjacent beam fields. In the example of Fig. 16, intensity is represented by shading of the lines representing beams 164 and 165. As shown, the lines are darkest at non- overlapping areas, representing maximum (or appropriate) intensity for that beam field. The lines become progressively lighter as the lines move into the overlap area, representing a decrease in intensity of (e.g., concentration of particles in) the respective particle beams. For example, in the case of particle beam 165, as the particle beam is moved during scanning in the direction of arrow 167, the intensity of particle beam 165 decreases when it enters the overlap area 166 and continues to decrease to a minimum value at the end of the overlap area 166 furthest into beam field 162. Likewise, in the case of particle beam 164, as the particle beam is moved during scanning in the direction of arrow 168, the intensity of particle beam 164 decreases when it enters the overlap area 166 and continues to decrease to a minimum value at the end of the overlap area 166 furthest into beam field 161 . In both cases, the intensities of the particle beams are controlled in the overlap areas such that the cumulative result from both beams in the overlap area is a uniform distribution of particles (or whatever other distribution is desired).

[00136] Thus, the overlap areas need not be avoided; appropriate doses of radiation are applied in the overlap areas; and the overlap areas between beam fields need not act as an impediment to automated operation of the treatment process. The configurable collimator described above may also be employed, where appropriate, to shape the beam at areas of overlap between adjacent beam fields or elsewhere. It is noted that the variations in intensity in the overlap areas are, effectively, a mitigation resulting from the risk of beam positioning

errors/uncertainties. If automated positioning of the particle beam is precisely controlled at all locations of the irradiation target, dose distributions may not need to be controlled in the manner described with respect to Fig. 16.

[00137] As noted, the combination of movement of the treatment couch and/or the particle beam may produce a relative rotational movement, a relative pivotal movement, and/or a relative translational movement. Rotational movements may be used, e.g., in IMPT treatments, whereas translational movements may be used, e.g., to treat across beam fields. Rotational movements and translational movements, or combinations thereof, are not limited to these contexts, and may have applicability outside of IMPT and treatment across beam fields. In some implementations, the system may implement an effective translational movement of 5cm or more, e.g., 5cm to 50cm or more, thereby enabling treatment of relatively long areas, such as a human spine, which could potentially span multiple beam fields.

[00138] The example particle therapy system may be controlled to implement any number of combined patient and beam positions that are appropriate for a given treatment plan. A combined patient and beam position may include any unique combination of a single position of the treatment couch (or patient) and a single position of the beam. By way of example, in a single treatment session, the example particle therapy system may be controlled to implement any appropriate number of combined patient and beam positions. Examples include, but are not limited to, two or more combined patient and beam positions, five or more combined patient and beam positions, ten or more combined patient and beam positions, 100 or more combined patient and beam positions, and 10,000 or more combined patient and beam positions. To reiterate, each combined patient and beam position is achieved through computer (e.g., automated) control over components of the particle therapy system (treatment couch, gantry, scanning components, etc.) and computer control over imaging system(s), such as the site imaging system(s) and the collision avoidance system. A TPS may provide appropriate instructions to effect control. In some implementations, the TPS may know beforehand the capabilities of the particle therapy system, and determine instructions for the treatment plan automatically based on a radiation dosage recommended by a medical professional and knowledge of the location, shape, and other relevant characteristics of the irradiation target (e.g., a tumor). Rather than limiting the number of beam fields, due to the various components described herein that enable beam positioning, in some examples, the particle therapy system described herein enables precise control over particle beam positioning, thereby effectively increasing the number of beam fields (e.g., to one for each position of the beam and patient) in order to increase the accuracy at which particle therapy is delivered.

[00139] The time for a treatment session will vary based on any number of factors including, but not limited to, the size of the target, the dosage to be applied, the number of combined patient and beam positions to be implemented, and so forth. In some cases, an average treatment time may be less than 15 minutes or less than 45 minutes in some examples.

[00140] Operation of the example particle therapy systems described herein, and operation of all or some component thereof, can be controlled (as appropriate), at least in part, using one or more computer program products, e.g., one or more computer programs tangibly embodied in one or more non-transitory machine- readable media, for execution by, or to control the operation of, one or more data processing apparatus, e.g., a programmable processor, a computer, multiple computers, and/or programmable logic components.

[00141] A computer program can be written in any form of programming language, including compiled or interpreted languages, and it can be deployed in any form, including as a stand-alone program or as a module, component, subroutine, or other unit suitable for use in a computing environment. A computer program can be deployed to be executed on one computer or on multiple computers at one site or distributed across multiple sites and interconnected by a network.

[00142] Actions associated with implementing all or part of the operations of the example particle therapy systems described herein can be performed by one or more programmable processors executing one or more computer programs to perform the functions described herein. All or part of the operations can be implemented using special purpose logic circuitry, e.g., an FPGA (field

programmable gate array) and/or an ASIC (application-specific integrated circuit).

[00143] Processors suitable for the execution of a computer program include, by way of example, both general and special purpose microprocessors, and any one or more processors of any kind of digital computer. Generally, a processor will receive instructions and data from a read-only storage area or a random access storage area or both. Elements of a computer (including a server) include one or more processors for executing instructions and one or more storage area devices for storing instructions and data. Generally, a computer will also include, or be operatively coupled to receive data from, or transfer data to, or both, one or more machine-readable storage media, such as mass PCBs for storing data, e.g., magnetic, magneto-optical disks, or optical disks. Non-transitory machine-readable storage media suitable for embodying computer program instructions and data include all forms of non-volatile storage area, including by way of example, semiconductor storage area devices, e.g., EPROM, EEPROM, and flash storage area devices; magnetic disks, e.g., internal hard disks or removable disks; magneto- optical disks; and CD-ROM and DVD-ROM disks.

[00144] Any "electrical connection" as used herein may imply a direct physical connection or a wired or wireless connection that includes intervening components but that nevertheless allows electrical signals to flow between connected

components. Any "connection" involving electrical circuitry that allows signals to flow, unless stated otherwise, is an electrical connection and not necessarily a direct physical connection regardless of whether the word "electrical" is used to modify "connection".

[00145] Any two more of the foregoing implementations may be used in an appropriate combination with an appropriate particle accelerator (e.g., a

synchrocyclotron). Likewise, individual features of any two more of the foregoing implementations may be used in an appropriate combination.

[00146] Elements of different implementations described herein may be combined to form other implementations not specifically set forth above. Elements may be left out of the processes, systems, apparatus, etc., described herein without adversely affecting their operation. Various separate elements may be combined into one or more individual elements to perform the functions described herein.

[00147] In some implementations, the synchrocyclotron used in the particle therapy system described herein may be a variable-energy synchrocyclotron. In some implementations, a variable-energy synchrocyclotron is configured to vary the energy of the output particle beam by varying the magnetic field in which the particle beam is accelerated. For example, the current may be set to any one of multiple values to produce a corresponding magnetic field. In an example implementation, one or more sets of superconducting coils receives variable electrical current to produce a variable magnetic field in the cavity. In some examples, one set of coils receives a fixed electrical current, while one or more other sets of coils receives a variable current so that the total current received by the coil sets varies. In some implementations, all sets of coils are superconducting. In some implementations, some sets of coils, such as the set for the fixed electrical current, are

superconducting, while other sets of coils, such as the one or more sets for the variable current, are non-superconducting (e.g., copper) coils.

[00148] Generally, in a variable-energy synchrocyclotron, the magnitude of the magnetic field is scalable with the magnitude of the electrical current. Adjusting the total electric current of the coils in a predetermined range can generate a magnetic field that varies in a corresponding, predetermined range. In some examples, a continuous adjustment of the electrical current can lead to a continuous variation of the magnetic field and a continuous variation of the output beam energy.

Alternatively, when the electrical current applied to the coils is adjusted in a non- continuous, step-wise manner, the magnetic field and the output beam energy also varies accordingly in a non-continuous (step-wise) manner. The scaling of the magnetic field to the current can allow the variation of the beam energy to be carried out relatively precisely, thus reducing the need for an energy degrader. An example of a variable-energy synchrocyclotron that may be used in the particle therapy system is described in U.S. Patent Publication No. 2014/037151 1 entitled "Particle Accelerator That Produces Charged Particles Having Variable Energies", the contents of which are incorporated herein by reference. Implementations that employ a variable-energy synchrocyclotron

[00149] In some implementations, a particle accelerator other than a synchrocyclotron may be used in the particle therapy system described herein. For example, a cyclotron, a synchrotron, a linear accelerator, or the like may be substituted for the synchrocyclotron described herein. Although a rotational gantry has been described (e.g., the outer gantry), the example particle therapy systems described herein are not limited to use with rotational gantries. Rather, a particle accelerator may be mounted, as appropriate, on any type of robotic or other controllable mechanism(s) - characterized herein also as types of gantries - to implement movement of the particle accelerator. For example, the particle accelerator and/or the spreader may be mounted on or more robotic arms to implement rotational, pivotal, and/or translational movement of the accelerator and/or the spreader relative to the patient. In some implementations, the particle accelerator and/or the spreader may be mounted on a track, and movement along the track may be computer-controlled. In this configuration, rotational and/or translational and/or pivotal movement of the accelerator and/or the spreader relative to the patient can also be achieved through appropriate computer control.

[00150] In some implementations, the particle accelerator itself may not move relative to the patient, as described herein. For example, in some implementations, the particle accelerator may be a stationary machine or at least not mounted for movement relative the patient. In examples like this, the particle accelerator may output its particle beam from the extraction channel to a transmission channel. The transmission channel may include magnets and the like for controlling magnetic fields contained therein in order to transport the particle beam to one or more remote locations, such as one or more treatment rooms. In each treatment room, the transmission channel may direct the beam to a beam spreader or other apparatus that is mounted for movement as described herein (e.g., to an outer gantry or other device). The beam spreader may thus be in place of the accelerator described elsewhere herein. However, in some examples, except for positioning of the accelerator, the spreader, and the transmission channel, the configuration and operation of this implementation of the particle accelerator system is the same as the configuration and operation of other implementations of the particle therapy system described elsewhere herein, as appropriate.

[00151] For example, using appropriate command and control protocols, in an example, the computer system 140 that directs operation of the particle therapy system controls operation, including positioning, of one or more of the gantry- mounted spreader (including translational, pivotal movement, and/or rotational movement), the beam shaping elements, the range modulator, the configurable collimator, the carriage to which the beam shaping elements are coupled, a nozzle, and the treatment couch to position the particle beam at an appropriate location in the treatment space to administer radiation dosage to a target. Using appropriate command and control protocols, in an example, the computer system that directs operation of the particle therapy system controls operation of the treatment couch to position the patient, and thus the irradiation target, at an appropriate location in the treatment space to administer radiation dosage via the particle beam. Using appropriate command and control protocols, in an example, the computer system that directs operation of the particle therapy system also controls operation of the synchrocyclotron to produce a particle beam having characteristics (e.g., intensity, energy, etc.) that are appropriate to administer required doses of radiation at locations defined in a treatment plan. Instructions in the TPS state where and when radiation is to be applied, and define the positions of the various system components needed to provide the appropriate radiation. Other possible operations of the particle therapy system are as described elsewhere herein.

[00152] Another example implementation of a particle therapy system in which the control systems described herein may be implemented is described in U.S.

Patent No. 7,728,31 1 entitled "Charged Particle Radiation Therapy", the contents of which are incorporated herein by reference. The content incorporated by reference includes, but is not limited to, the description of the synchrocyclotron and the gantry system holding the synchrocyclotron found in U.S. Patent No. 7,728,31 1.

[00153] Other implementations not specifically described herein are also within the scope of the following claims.

[00154] What is claimed is: