ABSTRACT
This chapter describes the system components after the target as well as the overall mechanical design of various commercial medical linacs. Linac technology developed quickly in the subsequent decade and in 1968 Varian Associates Inc. released the “Clinac 4” treatment unit, which was a C-arm linear accelerator system. The most advanced linac-based treatment units to emerge in MR-guided linacs in which a linear accelerator is combined with an magnetic resonance imaging unit. The CyberKnife employs a compact X-band linac that is mounted on a robotic manipulator arm adopted from the automotive industry. Like many modern linacs they employ the C-arm design in which a gantry rotates around the patient. The main disadvantage of treatment with Co is the steeper depth-dose falloff due to the lower energy photons and also the larger sources size which results in worse penumbra.
