Future of SBRT with Photon and Charged Particles

The previous chapters have described the evolution of the SBRT with photon beams to date, and further evolution in many respects is expected in the future. In this chapter, we describe what we can expect for the future of SBRT using photons and charged particles. In SBRT using photons, irradiation at extremely high dose rates, called FLASH radiotherapy is expected to lead to less side effects while maintaining the therapeutic effect on the tumor, and is expected to be widely used in clinical applications in the future. Other promising developments include the concurrent combination of immunotherapy and SBRT, identification of predictors of risk of recurrence such as radiomics and liquid biopsy, and the application of SBRT to palliative care and benign diseases are also expected. SBRT using charged particles has been studied for localized malignancies such as lung cancer, hepatocellular carcinoma, and oligometastases. In recent years, charged-particle therapy techniques have made significant progress, including pencil-beam scanning irradiation and intensity-modulated particle therapy (IMPT), which have been followed by the steady development of new treatment techniques such as proton beam FLASH therapy, LET distribution optimization therapy, and intensity-modulated combined particle therapy (IMPACT). Further studies and developments will enable this therapeutic technique to be used in clinical practice.