Charged particles in stereotactic radiosurgery

Charged particle radiotherapy has distinct physical and radiobiological advantages when compared to photon radiation. The depth–dose distribution of particles is characterized by a Bragg peak which results in minimal dose delivery beyond the treatment volume and, consequently, relative sparing of organs-at-risk. Additionally, the therapeutic efficacy of particle therapy is less likely to be influenced by intrinsic mechanisms of radioresistance such as hypoxia and cell cycle position. Recent advances in patient positioning, immobilization, and image-guidance have allowed investigation into particle radiosurgery, which combines particle therapy with a hypofractionated, stereotactic treatment approach. While the preliminary local control, survival, and toxicity outcomes from studies of multiple tumor sites are promising, randomized controlled trials are needed to determine whether improved efficacy and reduced morbidity justify the use of particle radiosurgery despite higher financial costs.​