Motion compensation with a scanned ion beam: a technical feasibility study.
BACKGROUND
Intrafractional motion results in local over- and under-dosage in particle therapy with a scanned beam. Scanned beam delivery offers the possibility to compensate target motion by tracking with the treatment beam.


METHODS
Lateral motion components were compensated directly with the beam scanning system by adapting nominal beam positions according to the target motion. Longitudinal motion compensation to mitigate motion induced range changes was performed with a dedicated wedge system that adjusts effective particle energies at isocenter.


RESULTS
Lateral compensation performance was better than 1% for a homogeneous dose distribution when comparing irradiations of a stationary radiographic film and a moving film using motion compensation. The accuracy of longitudinal range compensation was well below 1 mm.


CONCLUSIONS
Motion compensation with scanned particle beams is technically feasible with high precision.
Gesellschaft für Schwerionenforschung, Abteilung Biophysik, Darmstadt, Germany. svenoliver.groezinger@siemens.com
Sven Oliver
SO
Grözinger
Christoph
C
Bert
Thomas
T
Haberer
Gerhard
G
Kraft
Eike
E
Rietzel
D003198:Computer Simulation; D004307:Dose-Response Relationship, Radiation; D005240:Feasibility Studies; D009038:Motion; D011829:Radiation Dosage; D011880:Radiotherapy Planning, Computer-Assisted / Q000295:instrumentation* / Q000379:methods*; D017356:Synchrotrons