Brachytherapy

In brachytherapy (Greek brachys - short, close) the radiation source is placed in immediate proximity to or directly into the area to be irradiated. As contrasted with teletherapy, brachytherapy allows radiation treatment from inside.

Contact therapy

In the conventional contact therapy of skin tumours, the radiation source is placed directly onto the tumour. If the radiation source is inserted into a body cavity, this treatment is referred to as intracavitary or intraluminal brachytherapy (such as with tumours of the cervix or oesophagus).

Interstitial brachytherapy

In contrast to contact therapy, interstitial (interstitial - situated between) brachytherapy is an invasive procedure, that is, tissue is penetrated by a surgical instrument. In the process, the radioactive source is placed directly into the tumour. To this end, needles are inserted into the diseased tissue and remain in the body throughout the therapy.

Another method is the permanent implantation of small metal pellets (seeds) containing a radioactive source (usually iodine-125). The seeds are implanted directly into the tumour and continuously emit short-range radiation over a longer period of time.

In most cases, the seeds remain in the patient's body permanently and do not have to be removed. This type of brachytherapy is used to treat prostate carcinomas and some brain tumours, for example.

Afterloading

As the direct handling of radioactive sources would result in a high radiation exposure of the medical personnel, today brachytherapy is predominantly performed using the so-called afterloading procedure. In a first step, tubes or hollow needles as source applicators for afterloading are inserted into the area to be treated.

The radioactive source is located inside the afterloading machine. By remote control, the source is inserted into the area to be irradiated via connecting guide tubes as soon as the personnel have left the treatment room.

The afterloading procedure is applied for contact therapies as well as for interstitial brachytherapies.

In clinical routine, iridium-192 is used as radioactive source for afterloading in most cases. As activity decreases over time, the source has to be replaced at regular intervals.