What should you know about basic radiotherapy physics and biology?

The treatment team calculates where radiation should enter, how its energy is distributed and how separate beams can overlap at the target. The biological aim is to create damage that cancer cells are less able to repair than normal cells.

Radiation transfers energy to tissue and can disrupt DNA directly or through reactive molecules formed inside cells. If the damage is extensive enough, a cell may stop dividing or die. Treatment planning uses imaging, beam shape, angle and energy to concentrate dose in the tumour region.

Treatment is often divided into sessions. The gaps allow healthy cells time to repair, while repeated exposure continues to affect cancer cells. The exact schedule depends on the cancer type, treatment goal, body area and nearby sensitive structures.

Attend the planning scan and follow positioning instructions carefully, because reproducible body position helps the beam reach the intended area. Keep any skin marks or fitted mask as directed, and tell the team about pregnancy, implanted electronic devices, previous radiotherapy and all medicines.

Report new effects rather than changing skin products or medicines yourself. Rest, drink according to your care plan and follow site-specific advice about washing, eating and activity.

Contact the radiotherapy team promptly for rapidly worsening pain, repeated vomiting, inability to drink, marked weakness, fever, new breathing difficulty, confusion or unexpected bleeding. Seek emergency help for severe breathing trouble, collapse or a sudden neurological change such as new weakness or difficulty speaking.

Ask what area is being treated, what the treatment is intended to achieve, how your position will be reproduced, which nearby organs shape the plan, what effects may occur during or after the course, and whom to contact outside clinic hours.