Parallel opposed fields radiotherapy explained

The treatment machine delivers one beam from one side of the target and another from the opposite side. Together, the fields create a planned dose through the area while the team shapes and positions the beams to account for the tumour, nearby organs, and your body position. This arrangement may be used for selected cancers in areas such as the breast, brain, pelvis, skin, head and neck, or bowel region. It is not suitable for every tumour. A planning scan, marks or a mould, and checks of your position help the team reproduce the setup at each visit.

Attend the planning appointment in the position used for treatment and tell the team about implanted devices, pregnancy, previous radiotherapy, or difficulty lying still. Wear comfortable clothing and follow any bladder or bowel instructions you receive. The beam itself is not felt, although the session includes positioning and safety checks. Side effects depend on the treated area and can include skin irritation, tiredness, nausea, hair loss in the treated region, or changes in bowel or bladder habits. Ask how to protect the skin and whether you should continue normal activities.

Tell your radiotherapy team promptly about severe or rapidly worsening pain, repeated vomiting, inability to drink, new confusion, weakness, breathing difficulty, or skin that is blistered or infected. For pelvic treatment, report heavy bleeding or inability to pass urine. For head or brain treatment, urgent assessment is needed for a seizure, sudden weakness, or a severe new headache. The urgency depends on the symptom and the body area being treated.

Why are parallel opposed fields suitable for my target? Which organs are close to the beams? How will you position me each day? What skin, bowel, bladder, or neurological effects should I report? Can I work, exercise, or travel during treatment?