Linac

Linac is an abbreviation for the term Linear Accelerator. Linear accelerator machines produce radiation that is referred to as high energy X-ray.

Linac machines may be dedicated or non-dedicated. Dedicated linac machines have the additional equipment to perform higher level treatments permanently attached to the radiation couch. This is the preferred method. Non-dedicated linac machines may be used for conventional radiation therapy and after adding the attachment, are used for higher level treatments. Non-dedicated linac machines are unable to acquire the same degree of precision and accuracy that dedicated machines may have.

Radiosurgery can be performed with linear accelerator machines. By definition, radiosurgery is a one session surgical procedure directed by a neurosurgeon and a radiation oncologist. The entire procedure occurs in one day, including immobilization, scanning, planning and the procedure itself. With radiosurgery, the radiation dose given in one session is usually less than the total dose that would be given with radiation therapy. However, the tumor receives a very high one time dose of radiation with radiosurgery, and smaller doses over time with radiation therapy. This is important since more radiation is delivered to surrounding healthy areas when a person undergoes a few (2–5) treatment sessions instead of one; this can result in more side effects, some of which may be permanent. More importantly, a reduced amount of radiation delivered to the tumor with each radiation therapy treatment, rather than a very high one time dose, can result in less tumor control and poorer outcomes than with radiosurgery.