Dynamic Collimation in Proton Therapy

Spot-scanned, intensity modulated proton therapy is a relatively new external beam radiation treatment modality where a series of mono-energetic pencil beams of protons are magnetically swept across a target to achieve some desirable dose distribution. While protons offer several radiological advantages over photon-based techniques, lower-energy treatments suffer from excessive multiple-Coulombic scattering in the air prior to reaching the patient surface. A novel dynamic collimation device has been proposed to assist in mitigating the effects of lateral beam spreading during treatment.  While recent studies have shown that significant dosimetric improvements can be achieved with dynamic collimation, there still exists a large breadth of research to be accomplished with regard to treatment planning optimization, investigating secondary neutron production, and prototype development prior to clinical implementation.