Brachytherapy is a form of radiotherapy and is an advanced form of treatment for mesothelioma. It has been used for over a century for the treatment of mesothelioma.

Radiotherapy is used to treat mesothelioma by ionizing radiation, thus killing cancer cells. Radiotherapy can be performed internally or externally. When radiotherapy is performed externally the radiation is put into the body from an object outside the body, which is usually called a linear accelerator.

When radiotherapy is performed internally radiation is put inside the body. Internal radiotherapy can also be called brachytherapy. "Brachy" comes from the Greek word for "short range." The radiation is put into the body at short range, thus, brachytherapy. Some other names for internal radiotherapy are sealed source radiotherapy, seed implantation radiotherapy or endocurietherapy.

The radiation is placed either inside the cancer source or very close to it. The radiation that is placed inside emits radiation killing the cancerous cells but can only kill up to a one inch diameter, so the radiation must be placed close to the cancerous site.

There are two different types of brachytherapy:

- temporary brachytherapy

- permanent brachytherapy

Temporary brachytherapy consists of placing the radioactive seeds (radiation) inside the body and then taking them out after a certain amount of time.

Permanent brachytherapy consists of placing the radioactive seeds inside the body and leaving them. The radioactive seeds actually stop emitting radiation after a certain amount of time but lay in the body causing no problems.

There are actually teams of people who administer the brachytherapy. Among this team are a radiation oncologist, a radiation physicist, a radiation therapist, and the person who manually does the procedure.

The radiation oncologist decides the area to be treated and the overall treatment plan, the radiation physicist decides the best equipment to be used to infuse the radiation, the dosimetrist decides the dosage to be given and helps in distributing the dose and the radiation therapist operates the equipment that administers the radiation.

Brachytherapy is considered to be a safer method of treatment for mesothelioma than other treatments for the cancer, but there are side effects of this procedure. Right after the procedure there is soreness at the site of the radiation there may also be swelling in the same area. Short-term side effects are soreness and bleeding at the site but generally only last a few days.