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Disponible en español: Radiación interna (braquiterapia)

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Internal Radiation (Brachytherapy)

A plain-language guide to brachytherapy, a type of internal radiation where a radiation source is placed in or near the tumor. Learn how it is placed, the types, and safety measures. Based on National Cancer Institute resources.

AI-assisted and source verified. Not reviewed by a healthcare professional unless specifically stated.

Sources last checked: 2026-07-14Last updated: 2026-07-14Next planned review: 2027-07-14

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Cancer Explained uses AI to organize and translate information from the authoritative sources cited on each page. Automated checks review claims, citations, clarity, duplication, and potential safety concerns before publication. Our content is not currently reviewed by physicians unless a specific qualified reviewer is named on the page. Cancer Explained provides general education and should not replace advice from your healthcare team.

Editorial status — Source verified. This page was created with AI assistance and checked against the sources listed on it. Source checking is not a medical review.

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NCI source

National Cancer Institute

The short answer

Brachytherapy is internal radiation, where seeds, ribbons, or capsules holding a radiation source are placed in or near the tumor. It treats only a specific part of the body and is often used for cancers of the head and neck, breast, cervix, prostate, and eye. Some types leave your body radioactive for a while, so safety measures may be needed.

  • Brachytherapy places a radiation source in or near the tumor inside the body.

  • It is a local treatment, often used for head and neck, breast, cervix, prostate, and eye cancers.

  • The source may stay in place for minutes, days, or permanently, depending on the type.

  • The three main types are low-dose rate, high-dose rate, and permanent implants.

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The full explanation.

The simple version

Brachytherapy is a type of internal radiation therapy. Instead of aiming radiation from a machine outside your body, brachytherapy places the radiation source inside you — as seeds, ribbons, or capsules put in or near the tumor.

It is a local treatment, so it treats only a specific part of your body. It is often used for cancers of the head and neck, breast, cervix, prostate, and eye.

With brachytherapy, the radiation comes from a source placed inside your body, close to the cancer.

Before your first treatment

You will have a 1- to 2-hour meeting with your doctor or nurse to plan your treatment. You will have a physical exam, talk about your medical history, and maybe have imaging tests. Your doctor will discuss which type of brachytherapy is best for you, its benefits and side effects, and how to care for yourself. You can then decide whether to have it.

How the source is placed

Most brachytherapy is put in place through a catheter, which is a small, stretchy tube. Sometimes a larger device called an applicator is used instead. Your doctor places the catheter or applicator into your body before treatment begins.

There are several techniques, depending on your cancer:

  • Interstitial brachytherapy places the source within the tumor itself, as with prostate cancer.
  • Intracavity brachytherapy places the source within a body cavity, such as the vagina to treat cervical or endometrial cancer.
  • Episcleral brachytherapy attaches the source to the eye, used for melanoma of the eye.
  • Radioembolization places tiny radioactive beads into the main blood vessel that carries blood to the liver, used for liver cancer or cancer that has spread there.

Once the catheter or applicator is in place, the radiation source is placed inside it. How long it stays depends on the type of source, your cancer, where it is, your health, and other treatments you have had.

The three main types

Low-dose rate (LDR) implants. The radiation source stays in place for 1 to 7 days. You are likely to be in the hospital during this time. When treatment is finished, your doctor removes the source and the catheter or applicator.

High-dose rate (HDR) implants. The source is left in place for just 10 to 20 minutes at a time and then taken out. You may have treatment twice a day for 2 to 5 days, or once a week for 2 to 5 weeks, depending on your cancer. The catheter may stay in place or be put in before each treatment.

Permanent implants. After the source is put in place, the catheter is removed. The implants stay in your body for life, but the radiation gets weaker each day until almost all of it goes away. When the radiation is first placed, you may need to limit your time around others and take safety measures — especially being extra careful around children and pregnant women.

When the catheter is removed

Once you finish LDR or HDR treatment, the catheter is removed. Here is what to expect:

  • You will get medicine for pain before it is removed.
  • The area may be tender for a few months.
  • There is no radiation in your body after removal, so it is safe for others to be near you, even young children and pregnant women.

For a week or two, you may need to limit activities that take a lot of effort. Ask your doctor which activities are safe.

Safety while you give off radiation

With brachytherapy, the radiation source in your body will give off radiation for a while. If the dose is very high, you may need safety measures such as staying in a private hospital room. Hospital staff will give you all the care you need but may stand at a distance, talk from the doorway, or wear protective clothing.

Visitors may also need to follow rules, such as keeping visits short (about 30 minutes or less each day), standing by the doorway, and avoiding visits from pregnant women and children younger than one year. Your doctor or nurse will explain any safety measures to follow at home.

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Common questions

What is brachytherapy?

Brachytherapy is a type of internal radiation therapy in which seeds, ribbons, or capsules that contain a radiation source are placed in your body, in or near the tumor. It is a local treatment that treats only a specific part of the body and is often used for cancers of the head and neck, breast, cervix, prostate, and eye.

How is the radiation source put in place?

Most brachytherapy is placed through a catheter, a small stretchy tube, or sometimes a larger device called an applicator. Your doctor places the catheter or applicator into your body, and then the radiation source is placed inside it. How it is placed depends on your type of cancer.

How long does the radiation source stay in?

It depends on the type. With low-dose rate implants, the source stays 1 to 7 days. With high-dose rate implants, it is left in for only 10 to 20 minutes at a time. With permanent implants, it stays in your body for the rest of your life, but the radiation gets weaker each day until almost all of it goes away.

Will I give off radiation during brachytherapy?

Yes, the radiation source in your body will give off radiation for a while. If the dose is very high, you may need safety measures, such as staying in a private hospital room and limiting close contact with visitors, especially pregnant women and young children.

What happens when the catheter is removed?

After low-dose or high-dose rate treatment, the catheter or applicator is removed. You will get medicine for pain first. The area may be tender for a few months. Once it is removed, there is no radiation in your body, and it is safe for others to be near you.

Are there activities I should avoid?

For a week or two after treatment, you may need to limit activities that take a lot of effort. Ask your doctor which activities are safe for you and which ones to avoid.

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  1. Q1.According to this article, what is brachytherapy?
  2. Q2.According to this article, how long does the source stay in with a high-dose rate (HDR) implant?
  3. Q3.According to this article, is there radiation in your body after the catheter is removed following LDR or HDR treatment?
  4. Q4.According to this article, which cancers is brachytherapy often used to treat?

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How this page was created

Cancer Explained uses AI to organize and translate information from the authoritative sources cited on each page. Automated checks review claims, citations, clarity, duplication, and potential safety concerns before publication. Our content is not currently reviewed by physicians unless a specific qualified reviewer is named on the page. Cancer Explained provides general education and should not replace advice from your healthcare team.

Editorial status: Source verified This page was created with AI assistance and checked against the sources listed on it. Source checking is not a medical review.

Human medical review: not completed. At this time, most Cancer Explained content has not been reviewed by a physician or other healthcare professional. Pages with documented human medical review identify the reviewer, credentials, and review date directly.

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Internal Radiation (Brachytherapy)