TA25-Stereotactic Radiosurgery/Radiotherapy, Linac, CyberKnife

Fang-Fang Yin, Ph.D.

Stereotactic radiosurgery (SRS) of an intracranial lesion, or radiosurgery, combines the use of a stereotactic apparatus and energetic radiation beams to irradiate the lesion with a single treatment. Stereotactic body radiosurgery (SBRS) of a lesion outside of the brain combines the use of a stereotactic apparatus and energetic radiation beams to irradiate the lesion with a single treatment. Stereotactic Radiotherapy (SRT) utilizes the stereotactic apparatus and radiation beams for multiple fractions or treatments. The key steps for SRS/SRT involve (1) Accurately define the shape and location of the lesion and critical normal structures/organs in the reference frame of a stereotactic frame system with CT, MRI or angiography, etc. and incorporate information from other anatomical/functional images; and (2) Develop and deliver the planned treatment.  The treatment techniques produce a concentrated dose in the lesion with steep dose gradients external to the treatment volume. The rapid dose falloff from the edge of the treatment volume provides dramatic sparing of normal brain tissues. In this lecture, advanced technologies such as image-guided frameless and intensity-modulated methods will be described for SRS/SRT. Specific discussions will involve how these techniques could be effectively implemented in the each step of treatment procedures such as immobilization, simulation, treatment planning, target localization, delivery, and verification.