ABSTRACT
Linear accelerators (linacs) have been in use since 1953 when a device built by Metropolitan-Vickers was installed at Hammersmith Hospital in London, England with a photon energy of 8 megavoltage. Several manufacturers were selling add-on accessories and planning systems for linac-based stereotactic treatments. The latest generation of linacs offers a full panoply of radiation modalities, including multiple electron and photon energies, conventional or flattening filter-free modes, and micromultileaf collimators (MLC) and/or circular collimators for precise small field treatments. Department of Radiation Oncology in 1997 and included a miniature MLC permanently installed to the linac. One of the most technologically innovative is MLC tracking. While the target motion is tracked the motion data are fed to the MLC processors and the MLC leaf positions are adjusted to cover the target as it moves. The High Definition Multileaf Collimator with 2.5-mm central leaves is standard with the TrueBeam STx, while the Millennium MLC is standard with the TrueBeam system.
