Brachytherapy, or internal radiation, is used when a high dose of radiation needs to be delivered to a deep area of the body. Rather than coming from machines outside the body, the radiation source is placed inside the body. The radioactive material – encased in seeds – is placed within or adjacent to the tumor. The advantage of this technique is the sparing of adjacent structures such as the rectum and bladder.

The radioactive implants are usually placed directly into the prostate using a hollow needle. With low-dose brachytherapy, the radioactive seeds may be placed permanently, though the radioactivity of the material diminishes over time. This is more commonly used to treat less aggressive cancers.

For patients who wish to avoid low dose radiation exposure to their loved ones, radioactive seeds can temporarily be placed within the prostate to treat the cancer. This is called high-dose rate brachytherapy and is generally used to treat more aggressive cancers.

Patients undergoing brachytherapy should consult with their doctors about the risk of radiation exposure to people around them.