Programmable Particle Scatterer for Radiation Therapy Beam Formation

Abstract

Interposing a programmable path length of one or more materials into a particle beam modulates scattering angle and beam range in a predetermined manner to create a predetermined spread out Bragg peak at a predetermined range. Materials can be “low Z” and “high Z” materials that include fluids. A charged particle beam scatterer/range modulator can comprise a fluid reservoir having opposing walls in a particle beam path and a drive to adjust the distance between the walls of the fluid reservoir under control by a programmable controller. A “high Z” and, independently, a “low Z” reservoir, arranged in series, can be used. When used for radiation treatment, the beam can be monitored by measuring beam intensity, and the programmable controller can adjust the distance between the opposing walls of the “high Z” reservoir and, independently, the distance between the opposing walls of the “low Z” reservoir according to a predetermined relationship to integral beam intensity. Beam scattering and modulation can be done continuously and dynamically during a treatment in order to deposit dose in a target volume in a predetermined three dimensional distribution.

1 - 32 . (canceled) 
     
     
         33 . An apparatus for scattering and/or modulating a range of a charged particle beam, the apparatus comprising:
 high Z material having a path length in a path of a charged particle beam;   low Z material having a path length in the path of the charged particle beam, at least one of the high Z and low Z materials including a liquid; and   a controller configured to adjust the path lengths of the high Z and low Z materials during exposure of a target to the charged particle beam.   
     
     
         34 . The apparatus of  claim 33  wherein the path lengths of the high Z and low Z materials are independently adjustable. 
     
     
         35 . The apparatus of  claim 33  wherein the path length of the low Z material and, independently, the path length of the high Z material are continuously adjustable. 
     
     
         36 . The apparatus of  claim 33  wherein the controller is programmable. 
     
     
         37 . The apparatus of  claim 33  wherein the charged particle beam includes protons. 
     
     
         38 . The apparatus of  claim 33  further including:
 a source of charged particles that provides the charged particle beam.   
     
     
         39 . The apparatus of  claim 38  wherein the source is a cyclotron. 
     
     
         40 . The apparatus of  claim 39  wherein the cyclotron is a synchrocyclotron. 
     
     
         41 . The apparatus of  claim 40  wherein the low Z and high Z materials are in an extraction channel of the synchrocyclotron. 
     
     
         42 . The apparatus of  claim 39  further including:
 a beam monitor configured to measure intensity of the charged particle beam, the beam monitor communicating the intensity to the controller, the controller adjusting the low Z and, independently, the high Z path lengths according to integral intensity.   
     
     
         43 . The apparatus of  claim 42  wherein the controller is configured to adjust the path length of the low Z material and, independently, the path length of the high Z material continuously and dynamically. 
     
     
         44 . A method of scattering and/or modulating a range of a charged particle beam, comprising:
 directing the charged particle beam through a high Z material having a path length in a charged particle beam path;   directing the charged particle beam through a low Z material having a path length in the charged particle beam path, at least one of the high Z and low Z materials including a liquid; and   adjusting the path lengths of the high Z and low Z materials during exposure of a target to the charged particle beam.   
     
     
         45 . The method of  claim 44  wherein adjusting the path lengths of the high Z and low Z materials includes adjusting the path lengths independently. 
     
     
         46 . The method of  claim 44  wherein the path length of the low Z material and, independently, the path length of the high Z material are continuously adjustable. 
     
     
         47 . The method of  claim 44  further including:
 measuring intensity of the charged particle beam; and   wherein adjusting the path lengths of the high Z and low Z materials includes adjusting the path lengths according to the intensity.   
     
     
         48 . The method of  claim 47  wherein adjusting the path lengths of the high Z and low Z materials includes adjusting the path lengths continuously and dynamically. 
     
     
         49 . The apparatus of  claim 44  wherein the charged particle beam includes protons. 
     
     
         50 . The method of  claim 49  further including:
 producing the charged particle beam.   
     
     
         51 . The method of  claim 50  wherein the charged particle beam is produced by a cyclotron. 
     
     
         52 . The method of  claim 51  wherein the cyclotron is a synchrocyclotron. 
     
     
         53 . The method of  claim 52  wherein the low Z and high Z materials are in an extraction channel of the synchrocyclotron. 
     
     
         54 . The method of  claim 44  wherein the target is within a patient.