In brachytherapy, a radioactive substance (radioactive isotope) is placed directly into, or very close to, the tumour (called an implant). The radioactive substance can also be placed in the area where the tumour was removed. Brachytherapy is also called internal radiation therapy, short-distance radiation therapy, implant therapy or sealed radiation therapy.
Radioactive substances come in several different forms, including special applicators, thin wires, tubes (catheters), ribbons, needles, capsules or small seeds. Depending on the type of implant, the radiation source will stay in place for minutes, hours, days or permanently.
Brachytherapy makes it possible to treat a cancer with a larger dose of radiation than can be given with external beam radiation therapy. Radiation can be given directly to cancer cells and less radiation goes to nearby normal tissue.
The radioactive materials used for brachytherapy include:
The time it takes for half of a material’s radioactivity to disappear is called the half-life. Different radioactive materials have different half-lives. This information helps the radiation therapy team to choose the type of material to use and plan the treatment regimen. It also determines how long radiation safety precautions must be taken following treatment.
The implant may be placed in the body in the following ways:
Much of the planning for brachytherapy is done during the same appointment that treatment is given. Planning is done just before the actual radiation dose is delivered. Preparation for brachytherapy varies depending on the:
An anesthetic may be given before the implant is placed. People receiving brachytherapy may be told not to eat or drink anything after midnight the night before the procedure, especially if they will have a general anesthetic.
The dose given depends on the amount of tissue being treated, the type of radioactive material and how it is delivered. Imaging tests and computers may be used to help the healthcare team plan treatment. Sometimes, the total dose of radiation may be divided into a few smaller doses (called fractions) when high-dose brachytherapy is given.
Receiving brachytherapy can be a frightening experience if children don’t know what is happening to them. Because they are frightened, children may not want to or can’t cooperate during the treatment process. Helping children understand what is happening and preparing them for treatment will reduce their fears and will allow them to work with the radiation therapy team.
Children and parents may be shown what the implants look like, how the implants are placed (with the use of puppets) and any machines that might be used during treatment. The healthcare team will explain radiation safety precautions.
Brachytherapy is given in a hospital or cancer treatment centre. Usually, brachytherapy is given on an outpatient basis, but sometimes a person may have to be admitted for treatment. This depends on the area being treated, the type of brachytherapy and the person’s overall health.
Brachytherapy implants are usually placed in an operating room. The person receiving the implant will be given an anestheticanestheticA drug that causes anesthesia (the loss of some or all feeling or awareness). or sedative.
Implants can be temporary or permanent. They may be a source of radiation themselves (such as seeds, capsules, wires or needles) or they may be the way radiation is delivered (such as special hollow applicators or soft tubes called catheters). Doctors may use an ultrasound, computed tomography (CT) scan or other imaging tests to help ensure that they place the implants into the tissue or body cavity in the right spot.
The radiation therapy team plans the dose and length of time for the treatment. They use computers to help outline the treatment area and calculate and plan treatment. After the team determines the right radiation dose and gets the radioactive sources, they place the implants.
Sometimes, the total dose of radiation may need to be divided into several smaller doses (called fractions) when high-dose brachytherapy is given.
A permanent implant stays in place for the rest of the person’s life. Permanent implants may be small radioactive seeds or wires. Doctors may use very thin needles, tubes (catheters) or a special seed gun to insert the seeds. The implant gives off radiation over several weeks or months and the radiation gets weaker over time. The radioactive material is eventually used up.
The person may need to be in hospital for the first few days after the implant is placed, while the radiation is most active. The implants become less radioactive each day. The radiation in the body is very weak by the time the person goes home, but some safety precautions may be needed.
A temporary implant does not stay in place forever. Temporary implants use a container or applicator (such as a hollow tube) to hold the radiation source during therapy. Low-dose-rate (LDR) or high-dose-rate (HDR) therapy may be given using temporary implants.
LDR therapy delivers continuous, low doses of radiation over hours or days. The implants often stay in place for 1–7 days and then the doctor removes them. The person usually has to stay in the hospital and special radiation safety precautions are taken to make sure others are not exposed to radiation. Once the implant is removed, the person is not radioactive and can be around people.
HDR therapy delivers a single, high dose of radiation in a very short period of time. A single treatment usually takes a few minutes. The radioactive material travels from a special high-dose-rate machine attached to catheters or needles inserted into the tumour.
The person can usually go home after the treatment. Sometimes, a few treatments may need to be given over a few days. If so, the catheters are left in place and the person stays in the hospital.
The healthcare team removes the temporary implant when the desired dose of radiation has been given and the treatment is done. An anesthetic is not usually needed when temporary implants are removed. Most can be taken out right in the hospital room. Once the radioactive source is removed, there is no radioactivity left in the body and it is usually safe to be around other people.
The area that has been treated may be sore or sensitive for some time after brachytherapy is finished.
People receiving brachytherapy are usually admitted to a private room and isolated from other people in the hospital. This can be a difficult time because of restrictions placed on visiting and nursing care. Some activities may also be restricted, but the person receiving treatment can usually still read, watch television, listen to music or talk on the telephone. Nursing staff will provide all the care needed.
A radiation physicist may regularly measure the level of radioactivity in the room. They may also measure radioactivity in people receiving radiation therapy before they are discharged from the hospital.
Implanted radioactive sources put most of the radiation directly into the tumour, but they can give off some radiation. Special precautions are taken to ensure that others are protected and their exposure to radiation is limited. The length of time that precautions need to be taken varies with the type of brachytherapy used, but it is usually about 2–3 days.
A sign is placed on the door asking visitors to report to the nurse’s station before entering the room. This is done so visitors can be made aware of any precautions they need to take.
Precautions are based on some of the following principles.
Children under the age of 18 and pregnant women are not allowed in the room while the radiation source is active.
Staff or people receiving radiation should never touch a radioactive implant with their bare hands, even if the container is sealed. Touching it can cause radiation damage to the skin.
Body fluids, such as urine or stool, are usually not radioactive and do not require special handling.
Once an implant is removed, there is no radioactivity left in the body. However, people with permanent radiation implants may have to follow safety precautions at home for a period of time after the implant is placed.
The radiation therapy team will give people receiving internal radiation therapy special instructions about any safety precautions they need to follow and how long they need to take these precautions. People should talk to their radiation oncologist or radiation therapy team about any safety concerns or questions they have.
Radioactive material in a permanent implant can spread radiation outside the body. For this reason, people need to take some safety precautions for a period of time after they receive this type of treatment. For example, when radioactive seeds are used to treat prostate cancer, most of the radiation given off by the seeds stays inside the prostate. Radiation levels outside the pelvic area are very low, but safety precautions still need to be taken.
People with permanent radioactive implants (seeds) are told to take the following precautions.
Men with permanent implants for prostate cancer are also told to:
These precautions help limit other people’s exposure to radiation until the radioactive implant no longer gives off any radiation or becomes inactive.
Objects that a person touches or comes in contact with do not become radioactive.
Most people experience very few side effects from brachytherapy because healthy tissue is not affected very much by the radiation. Most side effects are very minor and last only a short time. Depending on the site of the implant, the side effects may be similar to that of external beam radiation therapy. These could include: