Novel technologies for Linac-based radiotherapy

The three most popular radiation oncology technologies are based on using beams of photons, electrons, and hadrons (protons and heavy ions). Photon radiotherapy is currently a quite mature and advanced technology. However, it continues to evolve toward improvement of its medical effectiveness and set new requirements for the radiation source, which is typically an electron linear accelerator (linac). For example, novel techniques that involve tumor irradiation from 4π angle or FLASH ultrafast delivery of large doses cannot be efficiently realized with the existing accelerators. At the same time, hadron radiotherapy promises improved treatment outcomes in certain cases. Efforts are underway to develop more compact hadron linac technologies with the ability to change the beam energy in millisecond time scales for efficient spot scanning. In this paper we will overview the current trends in linac technologies for electron, photon and hadron therapy, and provide examples of such developments at RadiaBeam.