Collimator and energy degrader

Abstract

A particle therapy system includes a particle accelerator to output a particle beam; and a scanning system for the particle accelerator to scan the particle beam across at least part of an irradiation target. The scanning system is configured to scan the particle beam in two dimensions that are at an angle relative to a direction of the particle beam. A structure defines an edge. The structure is controllable to move in the two dimensions relative to the irradiation target such that at least part of the structure is between at least part of the particle beam and the irradiation target. The structure includes a material that inhibits transmission of the particle beam.

What is claimed is: 
     
         1 - 42 . (canceled) 
     
     
         43 . A device to trim a particle beam, the device comprising:
 a structure that is movable in at least a first dimension relative to the particle beam, the structure comprising elements that are extendible from the structure along the first dimension and that are retractable, where positioning of the elements through at least one of extension or retraction of the elements defines an edge of the structure between a first part of the particle beam and a second part of the particle beam such that the structure blocks the first part of the particle beam while allowing the second part of the particle beam to pass, the edge at least partly collimating the second part of the particle beam.   
     
     
         44 . The device of claim  42 , wherein the structure is a first structure, the elements are first elements, and the edge is a first edge; and
 wherein the device comprises a second structure that is movable in at least the first dimension relative to the particle beam, the second structure comprising second elements that are extendible from the second structure along the first dimension and that are retractable, where positioning of the second elements through at least one of extension or retraction of the second elements defines a second edge of the second structure between a third part of the particle beam and a fourth part of the particle beam such that the structure blocks the third part of the particle beam while allowing the fourth part of the particle beam to pass, the edge at least partly collimating the fourth part of the particle beam.   
     
     
         45 . The device of  claim 44 , wherein movement of the second structure is based on movement of the first structure. 
     
     
         46 . The device of claim  42 , wherein the elements comprise fingers. 
     
     
         47 . The device of claim  42 , wherein the at least one dimension is defined by two Cartesian X and Y dimensions. 
     
     
         48 . The device of claim  42 , wherein the structure is rotatable. 
     
     
         49 . The device of claim  42 , which is controllable to move based on movement of the particle beam. 
     
     
         50 . A particle therapy system comprising:
 a particle accelerator to generate a particle beam;   at least one scanning magnet to move the particle beam relative an irradiation target in a patient; and   a collimator, between the at least one scanning magnet and the patient, to trim the particle beam on a spot-by-spot basis, the collimator comprising:
 a structure that is movable in at least a first dimension relative to the particle beam, the structure comprising elements that are extendible from the structure along the first dimension and that are retractable, where positioning of the elements through at least one of extension or retraction of the elements defines an edge of the structure between a first part of the particle beam and a second part of the particle beam such that the structure blocks the first part of the particle beam from reaching the patient while allowing the second part of the particle beam to reach the irradiation target, the edge at least partly collimating the second part of the particle beam. 
   
     
     
         51 . The particle therapy system of  claim 50 , wherein the at least one scanning magnet is controllable to move the particle beam more quickly for interior sections of the irradiation target than at a perimeter of the irradiation target. 
     
     
         52 . The particle therapy system of  claim 50 , wherein the at least one scanning magnet is configurable to move the particle beam from different incident angles; and
 wherein the collimator is controllable to move based on movement of the particle beam as the particle beam is moved from different incident angles.   
     
     
         53 . The particle therapy system of  claim 50 , wherein the collimator defines at least part of an aperture, and wherein the edge comprises an edge of the aperture. 
     
     
         54 . The particle therapy system of  claim 50 , wherein the particle accelerator comprises a synchrocyclotron comprising:
 a voltage source to provide a radio frequency (RF) voltage to a cavity to accelerate particles from a plasma column, the cavity having a magnetic field causing particles accelerated from the plasma column to move orbitally within the cavity;   an extraction channel to receive the particles accelerated from the plasma column and to output the received particles from the cavity; and   a regenerator to provide a magnetic field bump within the cavity to thereby change successive orbits of the particles accelerated from the plasma column so that, eventually, particles output to the extraction channel;   wherein the magnetic field is between 4 Tesla (T) and 20 T and the magnetic field bump is at most 2 Tesla.   
     
     
         55 . The particle therapy system of  claim 50 , further comprising:
 a gantry on which at least the particle accelerator is mounted, the gantry being configured to move the particle accelerator at least part-way around the patient.   
     
     
         56 . The particle therapy system of  claim 50 , further comprising:
 an energy degrader that is between the at least one scanning magnet and the patient, the energy degrader to receive the particle beam, the energy degrader comprising a beam-transmissible material that allows the particle beam to pass through the energy degrader and thereby change an energy of the beam; and   a control system to control operation of the energy degrader so that the energy degrader moves during movement of the particle beam, and to control operation of the collimator so that the collimator moves based on the movement of the particle beam.   
     
     
         57 . The particle therapy system of  claim 50 , wherein the elements comprise fingers. 
     
     
         58 . The particle therapy system of  claim 50 , wherein the at least a first dimension is defined by Cartesian X and Y dimensions. 
     
     
         59 . The particle therapy system of  claim 50 , wherein the structure is rotatable. 
     
     
         60 . The particle therapy system of  claim 50 , wherein the collimator is controllable to move based on movement of the particle beam. 
     
     
         61 . The particle therapy system of  claim 50 , wherein the edge comprises an edge of an aperture defined, at least in part, by the structure.