title: Present and future sources of protons and heavy ions.
mesh_terms: D001128:Argon; D002244:Carbon; D003365:Costs and Cost Analysis; D007477:Ions; D009356:Neon; D010315:Particle Accelerators; D011522:Protons; D011882:Radiotherapy, High-Energy; D014481:United States
chemical_list: D007477:Ions; D011522:Protons; D009356:Neon; D001128:Argon; D002244:Carbon