Summary
Radiation therapy uses precisely targeted radiation to damage cancer cells, delivered externally or internally, and is planned using detailed imaging to protect surrounding healthy tissue.
Key takeaways
- Radiation therapy damages cancer cell DNA using external or internal delivery methods.
- Imaging-based planning helps target tumours precisely while sparing healthy tissue.
- Treatment schedules range from a single dose to several weeks of daily sessions.
- Side effects are usually specific to the treated body area.
- Radiation can be curative, adjuvant, or palliative depending on the treatment goal.
What it is
Radiation therapy delivers focused doses of radiation to a tumour, either from a machine outside the body (external beam radiation) or from a radioactive source placed inside or near the tumour (brachytherapy). Modern techniques use imaging to precisely shape and target the radiation, sparing surrounding healthy tissue as much as possible.
What it means for you
Understanding whether your radiation is aimed at cure, preventing recurrence, or relieving symptoms helps set expectations for the treatment course and side effects. Your care team will explain the specific technique and schedule planned for your situation.
Testing
CT, MRI, or PET imaging is used during planning (simulation) to map the tumour precisely and design a treatment plan. Follow-up imaging after treatment assesses response and monitors for any late effects.
Associated cancer types
Radiation therapy is used for many cancers, including breast, prostate, lung, head and neck, brain, and cervical cancers, as well as for palliative relief of bone pain or spinal cord compression in advanced disease.
Treatment options
Options include external beam techniques such as IMRT or stereotactic radiosurgery, and internal approaches such as brachytherapy. The choice depends on tumour location, size, and whether the goal is cure, tumour shrinkage, or symptom relief.
Questions patients ask
- What is the goal of my radiation treatment—cure, shrinking the tumour, or symptom relief?
- How many sessions will I need and how long does each one take?
- What side effects are common for the specific area being treated?
- Will radiation be combined with chemotherapy or surgery in my case?
- What precautions, if any, are needed at home after treatment?
Frequently asked questions
Is radiation therapy painful?
The treatment itself is painless, similar to having an X-ray, though side effects like skin irritation or fatigue can develop over the course of treatment.
How many radiation sessions will I need?
This varies by cancer type and treatment goal, ranging from a single session to daily treatments over several weeks.
Will I be radioactive after treatment?
External beam radiation does not make you radioactive. Certain internal radiation treatments may require temporary precautions, which your care team will explain.
References
- 1.Radiation Therapy to Treat Cancer— National Cancer Institute
- 2.Radiotherapy— ESMO
- 3.What Is Radiation Therapy?— ASCO
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Last reviewed August 1, 2026
Medical disclaimer
Educational information only. GetOnco is software, not a medical provider, and does not diagnose disease or recommend treatments. Always discuss your situation with qualified healthcare professionals.