Abstract
Particle therapy is a radiotherapy modality in which accelerated protons or heavier ions are used to deliver a therapeutic dose to a treatment region. There are several advantages to using particle therapy over conventional photon therapy, including higher dose conformity, a higher relative biological effectiveness and increased healthy tissue sparing (particularly in the region behind the target). Due to the high dose conformity, large dose gradients will be present at the boundary between the treatment region and surrounding healthy tissue. Therefore, improvements in quality assurance techniques and development of methods to further improve the target-selectivity of particle therapy are two of the most important opportunities for enhancing the delivery of particle therapy.