Why is a linear accelerator used in intensity-modulated radiotherapy?

Intensity-modulated radiotherapy, or IMRT, divides the radiation plan into beam segments with different intensities. A linear accelerator produces the radiation and uses a multileaf collimator to adjust the beam shape as it moves through the planned angles. Computer planning coordinates these changes with the treatment position, helping create a dose pattern that fits the target while limiting exposure to nearby normal tissues as much as the plan allows.

The machine’s role is delivery, not diagnosis. The plan is reviewed and checked by the radiotherapy team before treatment, and therapists use imaging or other verification methods when indicated. IMRT may be delivered with a gantry that rotates around you, depending on the technique selected for your treatment area.

Follow the exact instructions for each appointment, including any guidance about a full or empty bladder, bowel preparation, food, medicines or skin care. Wear clothing that permits accurate positioning and remove items the team asks you to remove. Tell the therapist if pain, coughing or anxiety makes it hard to stay still. Report new symptoms between visits rather than changing the schedule yourself.

Contact your radiotherapy team for worsening skin irritation, persistent diarrhoea or vomiting, trouble swallowing, new pain, or fatigue that prevents usual activities. Seek emergency help for severe breathing difficulty, sudden confusion, fainting or uncontrolled bleeding. Symptoms vary with the treatment area, so the team’s written advice should guide you.

Ask how IMRT changes the beam pattern, how the target and nearby organs were considered, and what positioning checks occur before delivery. Ask which symptoms should be reported between appointments.