Stereotactic Radiosurgery for Residents-The Physics of Radiosurgery

Video Transcription
Video Summary
In this video, the speaker discusses the basics of medical physics and the principles of radiosurgery. The audience consists of radiation oncology and neurosurgery residents. The speaker begins by defining radiation as the process of energy emission or propagation, specifically electromagnetic radiation in the form of particles or waves. The types of radiation commonly used in radiosurgery are gamma rays and X-rays. The speaker explains the different units used to measure radiation, including activity (becquerel), absorbed dose (gray), and biological effect (sievert). They also discuss the concept of mega electron volts (MEV) as a unit of energy and how it relates to linear accelerators (LINACs) that emit a spectrum of photon energies.<br /><br />The speaker discusses the sources of photons used in radiosurgery, including radioactive decay (e.g., cobalt-60) and X-rays generated by the interaction of charged particles with the electric and magnetic fields of a nucleus (Bremsstrahlung interactions). They explain the components of a gamma knife and a LINAC, as well as the generation and shaping of photon beams. The speaker also touches on how photons interact with matter, primarily through Compton scattering. They explain the concept of absorbed dose (gray) and how the dose distribution is evaluated using dose-volume histograms and conformity indices.<br /><br />The speaker emphasizes the importance of accuracy and precision in radiosurgery due to the proximity of critical structures to target lesions. They discuss the methods used to aim radiation beams, such as stereotactic frames, onboard imaging, immobilization techniques, and gating. Treatment planning is explained, with forward planning and inverse planning both mentioned as approaches to creating treatment plans based on beam placement, beam weighting, and dose-volume constraints. The evaluation of treatment plans is discussed using metrics like dose-volume histograms and conformity indices. The video concludes with a mention of the sources of uncertainty in radiosurgery and the importance of considering margins and target delineation.<br /><br />The video provides a comprehensive overview of the key concepts and techniques involved in radiosurgery, aimed at an audience of radiation oncology and neurosurgery residents. No specific credits are provided in the video.
Asset Subtitle
Presented by David Schlesinger, PhD
Keywords
medical physics
radiosurgery
radiation oncology
neurosurgery
gamma rays
X-rays