Method and Apparatus for Controlled Pencil Beam Therapy

A system for providing real-time trajectory correction of a charged particle beam, comprising:

• a particle beam generator to generate a generated particle beam parallel to a reference axis;
• a transport beamline apparatus comprising beamline deflector magnets to generate magnetic fields to deflect said generated particle beam along a defined trajectory towards a scan nozzle;
• a scan nozzle comprising at least one scan magnet to direct said deflected particle beam to a target position in a patient;
• a first detector apparatus disposed between said transport beam apparatus and said scan nozzle, said first detector apparatus configured to output a first signal representing a first measured position of said deflected particle beam in orthogonal first and second planes, wherein said reference axis lies on said first and second planes;
• a second detector apparatus disposed between said first detector apparatus and said scan nozzle, said second detector apparatus configured to output a second signal representing a second measured position of said deflected particle beam in said first and second planes;
• a pair of first correction magnets disposed between said first detector apparatus and said particle beam generator, said first correction magnets configured to (a) receive from a control system an offset control signal and a beam angle control signal and (b) generate magnetic fields to correct a measured offset error and a measured beam angle error with respect to said first plane;
• and
• a pair of second correction magnets disposed between said first detector apparatus and said particle beam generator, said second correction magnets configured to (a) receive from said control system an offset control signal and a beam angle control signal and (b) generate magnetic fields to correct said measured offset error and said measured beam angle error with respect to said second plane;
• wherein said control system comprises a processor, said control system configured to:
• receive as inputs said first and second signals;
• calculate a measured trajectory of said deflected particle beam based on said first and second measured positions, said measured trajectory including a measured beam angle and a measured offset;
• determine said measured beam angle error based on said measured beam angle and a model beam angle of said generated particle beam;
• determine said measured offset error based on (a) at least one of said measured offset, said first measured position, or said second measured position and (b) a corresponding model position of said generated particle beam;
• generate said beam angle control signal based on said measured beam angle error;
• and
• generate said offset control signal based on said measured offset error.