A review on the technical and dosimetric aspects of stereotactic body radiation therapy (SBRT)

Stereotactic body radiation therapy (SBRT) or stereotactic ablative radiotherapy is currently enjoying much popularity due to its favorable outcomes. This treatment option had been derived from stereotactic radiosurgery (SRS) which uses focus irradiation technique to deliver a very high dose to a small intracranial target. The focus irradiation technique is performed using multiple collimated beams directed at the target from around the patient. Advancement in technology has provided similar tools on tomotherapy, modern medical linear accelerators, and dedicated system such as the Cyberknife to perform SBRT. Such tools include immobilization systems, 3D treatment planning systems, image-guidance system for precise localization, and accurate dose delivery systems. Each of these systems is being briefly reviewed. While the technical specifications of the equipment for SBRT are favorable, the dosimetric aspects need attention when performing treatment planning and managing target/organ motion. Because of the delivery of high doses in one or few fractions, special considerations must be given to transient doses through neighboring structures to avoid or reduce radiation toxicities for SBRT. Like SRS, direct involvement of medical physicists is essential for both the quality assurance and clinical procedures.