Stereotactic Therapy. Dr Aznar

Stereotactic radiotherapy is a technique that uses precisely targeted radiation to a tumor while minimizing radiation to adjacent normal tissue, utilizing stereotactic localization techniques. This targeting allows for the treatment of small to moderate-sized tumors, either in a single or a limited number of dose fractions.

STEREOTACTIC RADIOTHERAPY IS usually divided in: Stereotactic radiosurgery (SRS) (BRAIN) and Stereotactic Ablative (or Body) Radiotherapy (SABR/SBRT).

Stereotactic radiosurgery (SRS) and stereotactic radiotherapy (SRT) were initially used successfully for intracranial, orbital, and skull base tumors, as well as for benign conditions where the skull could be used as a reference system.
The success of SRS for intracranial indications led to the development of techniques to extend this approach to extracranial targets. Stereotactic radiotherapy for extracranial locations has required significant technical advances, including tumor imaging to guide radiation delivery, patient immobilization, and conformal radiation delivery techniques.
Stereotactic radiotherapy techniques require high geometric precision, a stereotactic immobilization and tracking system, and small or no margins. They include brain radiosurgery (SRS, e.g., 22 Gy/1#), fractionated brain radiosurgery (SRT, e.g., 27 Gy/3#), stereotactic body radiotherapy (SABR/SBRT, e.g., 40 Gy/3#, 55 Gy/5#, 60 Gy/8#), and fractionated stereotactic radiotherapy (fSRT, e.g., 50.4 Gy/28#).

The radiobiology of radiosurgery differs from that of conventional therapy in that the 5 “Rs” do not apply, nor does the linear quadratic model. The tumoricidal effect of radiosurgery is primarily due to damage to the vascular endothelium. The dose in radiosurgery must be considered a scalpel for both the tumor and healthy organs.