What should you know about an MRI linear accelerator?

MRI shows soft tissues and the treatment area during a session. The linear accelerator produces high-energy radiation aimed at the planned target. The team may use the images to check position, account for movement, and adapt the plan when the target or nearby organs do not look as expected. This approach is different from having a diagnostic MRI alone: it is part of a radiation treatment system.

Treatment planning considers the tumour, surrounding organs, your position, and how much radiation can be delivered safely. You may need to remain still and follow breathing or positioning instructions. The machine and the room are checked before treatment, and staff communicate with you throughout the appointment.

Tell the radiation team about implanted metal, a pacemaker or other electronic device, kidney problems, pregnancy, allergies, and difficulty lying still. Remove metal items as instructed and follow any preparation guidance about food, fluids, or medicines. During treatment, report pain, panic, or difficulty breathing rather than trying to tolerate it silently. Ask whether your plan is conventional radiotherapy or a more focused approach such as stereotactic body radiotherapy.

Contact your treatment team promptly for worsening pain, new weakness, confusion, repeated vomiting, fever, or skin changes that are becoming severe. Seek urgent help for trouble breathing, a seizure, sudden loss of movement, or a severe allergic reaction. These symptoms need assessment because they may reflect the treated area, a medicine, or another medical problem; they are not a way to judge whether cancer is present.

Which area will be treated, and how will MRI images guide the session? What should I expect during positioning and monitoring? How will you protect nearby organs? Which symptoms should prompt a same-day call, and who should I contact outside clinic hours?