Radiation Therapy Safety
Radiation therapy is a common way to treat many types of cancer. Still, it’s natural to have questions about its safety. Radiation therapy does expose you to hazardous radioactive particles, but it has been used to safely treat cancer for more than 100 years.
Learn more about how cancer care teams keep people safe during radiation therapy and what safety measures you might need to take for your type of radiation.
Is radiation therapy safe?
Radiation therapy is a safe treatment for many types of cancer.
Medical advances have led to safety regulations and checkpoints during treatment. Treatment centers must follow rules and regulations to keep patients, workers, and visitors safe.
Your cancer care team will give you exact safety instructions so you know what safety measures to take and how long to follow them. These will depend on your type of treatment and the type and dose of radiation you get.
If you know other people who had radiation therapy to treat cancer, your safety instructions might be different from theirs. Every person with cancer is different. You should follow your safety instructions exactly.
General radiation safety
When it comes to radiation safety, a common abbreviation used by experts is ALARA.
- ALARA stands for “as low as reasonably achievable.”
- This means people should limit being exposed to radiation that has no benefit to them.
- Keep in mind that it's impossible to avoid all radiation.
If you need radiation therapy to treat your cancer, your cancer care team will take special safety measures to protect other parts of your body from exposure to radiation.
Safety planning before treatment
Before you get radiation therapy, your cancer care team works carefully to make a treatment plan that is effective and safe. Treatment will focus on giving radiation to the cancer while limiting exposure of healthy tissue.
Your care team will review your treatment plan often during your therapy. The treatment team will use computers to monitor you and the amount of radiation you get.
Safety during radiation treatment
Every time you have radiation treatment, your treatment team will follow all safety rules. They will measure and monitor your dose to be sure you get your treatment safely.
You may notice the treatment team wearing special clothing and protective equipment when they are in the radiation therapy area. This is because they must meet certain regulations to limit their radiation exposure when caring for patients during treatment and imaging tests.
Safety for specific types of radiation
Not all radiation treatments work the same way or have the same safety precautions.
External beam radiation therapy is given from an outside source. It involves a beam of radiation aimed at a part of your body. This type of radiation affects the cells in your body only for a moment.
There is no radiation source inside your body, so you are not radioactive at any time during or after treatment.
Internal radiation therapy uses a sealed source of radiation. The source is put inside your body (implanted) where the cancer is found.
Depending on the type of implant used, your body may give off a small amount of radiation for a short time.
- If your implant is temporary, your body will no longer give off radiation once it is removed.
- If your implant is permanent, it will slowly stop giving off radiation after a while.
The radiation usually doesn’t travel much farther than the treatment area, so the chance of others being exposed is small. Still, you may need to be careful.
To keep others safe, you may need to:
- Stay in the hospital and limit visitors during treatment.
- Keep a certain distance away from visitors.
Pregnant people and children might not be allowed to visit you.
IORT is given during surgery, using different radiation methods like brachytherapy or electron beams. Depending on the type of radiation used, you may have to follow special instructions to keep you and others safe.
Talk with your cancer care team to see if you need to follow special safety measures.
During radioembolization, the radiation source stays near the tumor. The radiation travels a very short distance, so the effects are mostly to the tumor.
You might still have to limit contact with other people for up to one week after treatment.
It’s especially important to avoid close contact with children and pregnant people. Ask your treatment team what precautions you need to take.
Oral or systemic radiation uses an unsealed radioactive substance that goes through your whole body. Some radiation stays in your body for a few days until your body gets rid of it.
You may need to stay in the hospital for 1 or 2 days and take special precautions at home.
To protect others from radiation, the drugs are kept in special containers that hold the radiation inside. You’ll be treated in a shielded room that also keeps radiation contained. The radiation team might wear safety gear to protect themselves while they handle the radioactive drug.
Patient and family safety for oral or systemic radiation treatment
If you get systemic radiation treatment, you might need safety measures to protect the people around you. In most cases, you’ll only need to take these measures for the first few days after treatment.
After systemic radiation treatment, radioactive materials can leave your body through:
- Saliva
- Sweat
- Blood
- Urine
These fluids are radioactive when they leave your body. It's very important to limit radiation exposure to the people around you as much as possible.
For a certain amount of time, you might be told to:
- Wash your clothes, sheets, and towels separately from the rest of the household.
- Sit when using the toilet to avoid splashing body waste.
- Flush twice after using the toilet and wash your hands well.
- Use separate utensils and towels.
- Drink extra fluids to flush the radioactive material out of your body.
- Avoid kissing or sexual contact (often for at least a week).
- Keep a certain distance from other people. (For example: 1 arm’s length, 6 feet, etc.)
- Sleep in a separate bed in a separate room. This depends on the type of treatment you get.
- Avoid contact with infants, children, and pregnant people.
- Avoid contact with pets.
- Avoid public transportation.
- Plan to stay home from work, school, and other activities.
Learn more about radiation safety
The information here describes some of the safety concerns for different types of radiation therapy. You might need to take precautions during and after treatment, depending on the type of radiation you get.
It's very important that you understand what you need to do to protect the people around you. Talk to your cancer care team about your specific situation.
More on radiation therapy
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- References
Developed by the American Cancer Society medical and editorial content team with medical review and contribution by the American Society of Clinical Oncology (ASCO).
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Last Revised: June 9, 2025
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