Synopsis
Explain curative and palliative radiotherapy, connect target definition and fractionation to tumour control and normal-tissue risk, and recognise urgent, acute and late radiation toxicity.
- Radiotherapy deposits ionising energy that damages DNA directly and through free radicals; fractionation allows normal-tissue repair while repeated exposure accumulates tumour effect.
- Treatment may be definitive, neoadjuvant, adjuvant, consolidative or palliative and can use external beam, stereotactic techniques or brachytherapy.
- CT simulation, immobilisation, target and organ-at-risk contouring, dose planning and independent checks precede the first fraction.
- Dose and fractionation are tumour-, site- and intent-specific; use the current Royal College of Radiologists guidance and local protocol rather than memorised schedules.
- Radiosensitivity, oxygenation, concurrent systemic treatment, previous irradiation and normal-tissue reserve affect both control and toxicity.
- Acute effects occur in proliferating tissues during or soon after treatment; late fibrosis, vascular, neurological, endocrine and second-cancer effects can appear months or years later.
- Palliative radiotherapy can rapidly relieve bone pain, bleeding, obstruction or neurological risk, but emergency corticosteroid, surgery or stabilisation may also be needed.
- Pregnancy, implanted devices, transport burden and inability to reproduce position require early planning, not day-one improvisation.
Key red flags
Cord compression, airway compromise or cerebral oedema requires urgent multidisciplinary rescue; radiotherapy planning must not delay immediate stabilisation.
Investigation priorities
Create the reproducible geometry used for target and organ contouring.
Management branches
Radiotherapy is proposed after diagnosis and staging.
- Agree curative or palliative intent, alternatives and the evidence-based dose-fractionation option at MDT and consultation.
- Complete simulation, immobilisation and image fusion, then contour targets and organs at risk using tumour-specific standards.
- Perform physics optimisation and independent verification, including previous-dose review and pregnancy or device precautions before first exposure.