What should you know about megavoltage radiotherapy?

Megavoltage refers to the energy range used by modern external-beam radiotherapy machines. The beam is shaped and aimed from outside the body, with the goal of depositing dose in the tumour or treatment area. It may be used for conditions such as breast cancer, brain tumours, bowel cancer, womb cancer or head and neck cancer, depending on the diagnosis. Treatment is planned from scans and may use immobilisation, image guidance and several beam directions. The radiation itself is not felt, but the treated area can develop effects that appear during or after the course.

At the planning visit, ask which body area will be treated, whether you need special positioning, and how the team will protect nearby organs. Tell the team about pregnancy, implanted devices, previous radiotherapy, medicines and skin conditions. Attend appointments with clean, dry skin unless given different instructions, and follow advice about eating, drinking and skincare for your treatment area. Fatigue and local skin or tissue irritation can occur; report symptoms early so the team can offer practical support or adjust care.

Contact the radiotherapy team for rapidly worsening skin reaction, inability to drink, persistent vomiting, severe diarrhoea, new confusion, worsening headache, or pain that is difficult to control. Seek emergency help for severe breathing difficulty, collapse or signs of a serious allergic reaction. The urgency depends on the body area treated and any medicines given with radiation, so keep the treatment team’s contact instructions available.

Ask why megavoltage treatment is recommended, how the target and nearby organs will be mapped, what effects are expected in your treatment area, and which symptoms need same-day advice.