Hotspots of stereotactic body radiotherapy in radiobiology

Stereotactic body (SBRT) has been gradually proven to be effective in treating multiple solid tumors. Along with the development of image-guided (IGRT) system and radiotherapy, SBRT can form a high-dose region in the target area, whereas the dose gradient outside the target area declines rapidly. It not only delivers large-dose irradiation to the tumors, but also protects the surrounding normal tissues as possible, thereby implementing safe big fractionated radiotherapy . At present, regular understanding of the radiobiology underlying SBRT is still lacking. Multiple issues, such as applicability of linear quadratic (LQ) model, weakening of re-oxygenation, additional cell killing effect different from conventional fractionated and immune enhancement effect are still controversial. In this article, the above controversial hotspots were discussed and analyzed, aiming to deepen the understanding of the radiobiological characteristics of SBRT and contribute to promoting the application of SBRT in clinical practice. Key words: Stereotactic body radiotherapy; Radiobiology; Research progress