MR-Linac (MRI-Guided Radiotherapy)

MR-Linac is a hybrid system that builds an MRI scanner directly around a linear accelerator, the machine that produces the treatment beam. MRI gives an exceptionally clear view of soft tissue, far better than the x-ray imaging used in conventional radiotherapy, and crucially it does so continuously while the beam is on, without adding any extra radiation. This means the team is no longer treating from a picture taken days earlier; they can see exactly where the tumour and the surrounding organs are at that moment and respond. The approach is often called adaptive radiotherapy, because the plan can be refreshed to match the body as it is on the day.

Before each session, the live MRI shows the team the tumour's current size, shape and position. If anything has shifted since the original plan, a new plan can be created on the spot so the dose still fits the target precisely. During treatment the MRI keeps watching; if the tumour drifts outside a set boundary, for example as you breathe, the beam automatically pauses and resumes only when the target moves back into place. You lie still inside the machine, much as you would for an ordinary MRI, and feel nothing from the radiation itself. Sessions take longer than standard radiotherapy because of this extra imaging and on-the-day planning.

MR-Linac is especially suited to tumours that are hard to target because they move with breathing or sit close to delicate organs, such as cancers of the pancreas, liver, prostate, lung, and certain abdominal and pelvic sites. Its live soft-tissue view and adaptive planning allow higher, more focused doses in these situations while keeping nearby healthy organs better protected, which in some cases means a course can be given in fewer, more powerful sessions. Whether this technique fits a particular case always depends on the diagnosis and tumour location; a radiation oncologist decides after reviewing your imaging.

The main advantages are precision and adaptability: treating from a live image rather than an older scan, adjusting the plan to your anatomy each day, and gating the beam to motion all help concentrate the dose on the tumour while sparing healthy tissue, which can reduce side effects. Because the dose is so focused, some treatments can be completed in a shorter overall course. Treatment is non-invasive and given on an outpatient basis, with no surgery and no anaesthesia. The trade-off is that individual sessions last longer than conventional radiotherapy; your care team explains the schedule and supports you throughout.