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  • A cancer treatment in which radioactive materials are placed inside the body
  • Often used for cancers of the head and neck, breast, uterus, cervix, thyroid, and prostate
  • The goal is to maximize radiation to cancer cells, and protect exposure to healthy cells
  • Involves therapeutic radiology



If you have cancer and need radiation treatment, your doctor may decide that the most effective treatment will be a very intense form given to a small area of your body. This kind of cancer treatment is called internal radiation therapy. It is known by a variety of other names, too, including: implant radiation, interstitial radiation, intracavitary radiation or brachytherapy—all are forms of internal radiation therapy used to treat cancer today.

With internal radiation therapy, the doctor places a source of high-energy, radioactive rays (such as seed implants) inside the body as close as possible to the cancer cells. The goal is to maximize radiation to cancer cells while also minimizing exposure to normal cells, so they won’t be damaged. Some of the radioactive substances used for internal radiation treatment include radium, cesium, iridium, iodine, phosphorus, and palladium. Internal radiation therapy is frequently used for cancers affecting the head and neck, breast, uterus, thyroid, cervix, and prostate.

Another type of radiation therapy, called external radiation therapy, is different. As its name suggests, it gets delivered externally, by a large machine located outside of the body. For some patients, doctors recommend a combination of internal and external radiation therapy—it all depends on the kind of cancer you have and what stage it is in.

“When using internal radiation therapy, we can give a higher total dose of radiation in a shorter time than is possible with external treatment,” says Lynn Wilson, MD, a radiation oncologist who is the vice chair of Yale Medicine Therapeutic Radiology.

At Yale Medicine, we offer more internal radiation therapy or brachytherapy services than any other program in the state of Connecticut. We offer image-guided high dose rate brachytherapy (intra-cavitary and interstitial) services for patients with gynecologic malignancies, including cervical cancer, vaginal cancer, and uterine cancer. 

How is the radiation implant placed in the body?

For most types of implants, the implantation will be done in the hospital, as an outpatient procedure, under or local anesthesia. The doctor will surgically implant the applicators to deliver radioactive material from inside your body.

To get the radiation as close as possible to the cancer, doctors may use implants of radioactive material sealed in wires, seeds, capsules or needles. The type of implant and the method of placing it depend on the size and location of the cancer. 

Implants may be put right into the tumor, in special applicators inside a body cavity, on the surface of a tumor, or in the area from which the tumor has been taken.

The important thing is that the radiation source is placed right in the affected tissue, usually in small tubes or containers. These implants may be temporary or permanent.

Internal radiation also may be given by injecting a solution of radioactive substance into the bloodstream or a body cavity. When the substance is injected, it is not sealed in a container and may be called unsealed internal radiation therapy.

Is a radiation implant dangerous to others?

Nowadays, the majority of brachytherapy at Yale is performed via a technique called “remote afterloading,” which is done in a specialized high dose rate brachytherapy. With remote afterloading, the radioactive source is put into the applicator for a few minutes and is then removed. The applicators are left in place for subsequent treatments, but no radioactivity remains inside you at the end of each treatment, so there is no danger to others.

In other cases, low-dose radioactive implants are put in the body and remain there for longer periods. In this case, explains Dr. Wilson, “The radioactive substance in your implant may transmit rays outside your body. So while you're receiving this type of implant therapy, the hospital may require you to stay in a private room.” 

Nurses and other medical professionals will still be able to provide care, but they won’t spend extended periods of time in your room. Patients receiving this type of radiation implant are able to call for a nurse when one is needed, but should keep in mind that the nurse will work quickly and speak from the doorway more often than from your bedside. 

In most cases, urine and stool don’t contain no radioactivity. However, either one may contain some radioactive material if you have unsealed internal radiation therapy, in which cases special precautions will need to be taken.

If you are receiving a low-dose rate implant, there also will be limits on visitors while your implant is in place. Most hospitals do not let children younger than 18 or pregnant women visit patients who have an implant. Visitors should sit at least 6 feet from your bed and stay for only a short time each day (10 to 30 minutes). Have visitors ask your nurse for specific instructions before they enter your room.

Are there any side effects with internal radiation therapy?

You are not likely to have severe pain or feel ill during implant therapy. However, if an applicator is holding your implant in place, it may be somewhat uncomfortable. If you need it, the doctor will order medicine to help you relax or to relieve pain. Some patients feel drowsy, weak, or nauseated after having the anesthesia to place the implant, but these effects do not last long.

Be sure to tell the nurse if you have any side effects such as burning, sweating, or other unusual symptoms.

How long does the implant stay in place?

The total amount of time that an implant is left in place depends on the dose (amount) of radioactivity with which the patient is treated, as follows:

A high dose rate implant will remain in place for just a few minutes.

A low-dose rate implant is usually left in place for several days. How many will depend on the type of cancer, where it is, your general health, and other cancer treatments you have had. Your ability to move around depends on where the implant is located; in some cases, patients need to stay in bed and keep fairly still to keep the implant from shifting.

Some implants are left in place permanently. If your implant is permanent, you may need to stay in your room, away from other people in the hospital for a few days while the radiation is most active. The implant will lose energy each day, so by the time you are ready to go home, the radiation in your body will be much weaker. Your doctor will advise you if there are any special precautions you need to use at home to ensure proper treatment and the safety of yourself and loved ones.

Yet another kind of brachytherapy is called high dose rate remote brachytherapy. It allows a person to be treated within a few minutes in inpatient or outpatient clinics. With remote brachytherapy, a very powerful radioactive source is sent by remote control through tubes, or catheters, to the tumor. The radioactivity remains at the tumor for only a few minutes. This procedure is done by the brachytherapy team, who monitor patients on a closed-circuit television and speak through an intercom. In some cases, several remote treatments may be required. Sometimes, the catheter stays in place between treatments and sometimes it is removed, depending on your condition.

These high dose rate treatments are short (usually a few minutes) and result in less discomfort than other types of radiation therapy. Because radioactive materials are not left in your body, you can return home soon after you recover. Remote brachytherapy has been used to treat cancers of the cervix, uterus, vagina, breast, lung, pancreas, prostate, and esophagus.

What happens after the implant is removed?

Most patients don’t need anesthesia when the implant is removed. Often they can be removed bedside in the hospital room or the brachytherapy suite in the radiation department. If you had to stay in bed during implant therapy, you might have to remain in the hospital an extra day or so after the implant is removed. 

Once the implant is removed, there is no radioactivity in your body. The nurses and your visitors will no longer have to observe any special rules.

Your doctor will tell you if you should limit your activities after leaving the hospital. Most patients can do as much as they feel like doing. You may need some extra sleep or rest breaks during your first days at home, but you will feel stronger quickly.

The area that has been treated with an implant may be sore or sensitive for a while. Your doctor may advise you to limit sports and sexual activity for a while if they cause irritation in the treatment area.

Why are Yale Medicine radiation oncologists unique in their care of patients with internal radiation therapy?

At Yale Medicine, we are leading experts in providing brachytherapy services. We offer our patients the benefit of CT and/or MRI image-guided intra-cavitary and interstitial high dose rate brachytherapy for highly precise treatments of gynecologic malignancies.