Linac linear accelerator

The machine accelerates electrons and uses them to produce high-energy X-rays for external-beam radiotherapy. A gantry can rotate around the treatment couch, allowing the team to approach the target from planned directions. Beam-shaping parts help match the radiation to the treatment area, while the plan aims to reduce dose to nearby healthy tissue. You are not radioactive after a standard external-beam session.

Some plans use image guidance before or during delivery to check position. More focused approaches, including stereotactic body radiotherapy, may use a linac when the target and surrounding organs meet specific planning conditions. Your radiation oncologist chooses the technique, dose pattern and schedule.

The preparation usually includes a planning scan, measurements and a reproducible position. You may receive a mould, mask or other support to help you stay aligned. At each session, the therapists confirm your identity and positioning, then leave the room while observing you. Tell them if pain, anxiety or difficulty holding still could affect positioning. Keep appointments, protect treated skin from friction and ask before applying products to the area.

Contact the treatment team if you develop worsening redness, broken skin, severe tiredness, persistent nausea, diarrhoea, swallowing difficulty or a new neurological change. Emergency assessment is needed for severe breathlessness, a seizure, sudden confusion, collapse or rapidly worsening weakness. The right response depends on the treatment site, so use the contact number supplied by your centre rather than waiting for the next session.

Why is a linac suitable for my treatment? Will image guidance or a focused technique be used? What positioning device will I need? Which side effects relate to the treated area? How should I care for my skin, and when should I call?