Physics and Dosimetric Principles of SRS and SBRT

This paper reviews the radiation physics and dosimetric principles of stereotactic radiosurgery (SRS) and stereotactic body radiotherapy (SBRT).Recent radiation therapy physics and technology developments are reviewed followed by a brief description of the equipment available for SRS and SBRT.The treatment planning process and beam orientation optimization for SRS and SBRT are discussed.The dose calculation algorithms for radiation therapy are described including simple correction-based methods, advanced model-based algorithms and Monte Carlo simulations.Guidelines for SRS and SBRT treatment planning and plan evaluation are summarized including detailed dose prescription, organ dose tolerance and plan acceptance criteria.Finally, dosimetry measurements for SRS and SBRT are discussed with a focus on small field dosimetry.