Brachytherapy is a type of radiation therapy. It is also called internal radiation therapy. It uses a tiny radioactive source placed inside the body to treat cancer.
Brachytherapy may be used alone or with other treatments. It is most often used to treat certain sarcomas and retinoblastoma.
Brachytherapy uses a small radioactive source, such as a small seed, pellet, or thin tube, that contains radiation. This source is placed inside or very close to the tumor to deliver radiation directly to cancer cells.
The radiation source can be removed after a short time. Or it can stay in the body permanently. The radiation does not stay in the body. It fades until it is gone.
Benefits of brachytherapy
Unlike external beam radiation, brachytherapy delivers radiation inside or next to a tumor. This keeps most of the radiation close to the cancer cells and reduces radiation exposure to healthy tissues.
Brachytherapy can give a higher, more targeted dose than external beam radiation, which can mean fewer sessions.
Brachytherapy may cause fewer side effects than other types of radiation therapy.
Your care team will talk with you about the risks and benefits of brachytherapy and let you know what to expect. Your child will have a physical exam and lab tests to make sure they are ready for treatment. Your child will have imaging tests to help the care team make a treatment plan. Tests may include CT scans, MRIs, or x-rays.
Some patients need a temporary catheter to help the care team place the radiation source. When your child is ready, catheters are placed in or near the tumor. The type of catheter and procedure used depends on:
- The type of cancer your child has
- Where the tumor is
- What size and shape the tumor is
- Your child’s treatment plan
Your child will likely have anesthesia during the procedure to place the radiation source. This helps your child stay still and comfortable. Imaging tests may be used again to make sure everything is in the right place.
Your care team will explain which type of brachytherapy your child will have and what steps will be involved.
Brachytherapy can be delivered in 2 main ways:
- High dose rate (HDR): a strong dose of radiation is given quickly over a short period of time
- Low dose rate (LDR): a lower dose of radiation is given slowly over a longer period of time
HDR brachytherapy
During HDR brachytherapy, the care team connects your child’s catheter to a machine that holds the radioactive material. This machine delivers a full radiation dose to the tumor during a short session (about 10 – 20 minutes). The radiation source is then taken out of your child’s body.
Your child will be disconnected from the machine. The catheter will stay in place, and your child may stay in the hospital until all treatment sessions are done.
LDR brachytherapy
In LDR brachytherapy, the radioactive material is often contained in tiny seeds. These seeds are placed in or near the tumor. A temporary catheter may be used to make sure they go to the right place.
Radiation is released from the seeds slowly for hours, days, or sometimes longer. Some seeds may stay in the body permanently. Others are taken out later. The radiation will fade until it is gone.
The care team will watch your child for a short time to make sure they are comfortable and recovering well. If catheters were used, they are removed once the final treatment is done. LDR seeds may stay in the body.
Side effects of brachytherapy
Brachytherapy is generally safe. But it can have risks. The specific risks depend on the:
- Type of brachytherapy
- Location of the tumor
- Other treatments your child may get
- Your child may feel tired or have mild side effects after brachytherapy, including:
- Redness, irritation, or mild soreness near the treatment site
- Fatigue (feeling tired, weak, or worn out)
- Pain when urinating (going pee)
- Urinating a lot
- Mild diarrhea
- Swelling or soreness around the catheter or where the seeds were placed
- Bleeding or infection where catheters or seeds are placed
These side effects are usually temporary and get better over time. Possible long-term risks include damage to nearby healthy tissues or organs.
Care at home after brachytherapy
Most children feel tired for a few days. To help your child recover:
- Follow the care team’s instructions for care of the treatment site.
- Make sure your child rests, eats healthy foods, and drinks plenty of fluids.
- Watch for unusual side effects such as fever, heavy bleeding, or severe pain.
- Go to all follow-up visits.
When to call your care team
It is important to contact your child’s care team if you notice anything unusual after brachytherapy. This includes:
- Fever or signs of infection
- Heavy bleeding or swelling at the treatment site or where the catheter is
- Severe pain that does not get better with the medicine your care team prescribed
- Trouble urinating
- Diarrhea that gets worse
- Any other unusual or concerning changes
Questions to ask your care team
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Reviewed: February 2026
