External beam radiotherapy
In external beam radiation the treatment area is irradiated from the outside - through the skin. In order to include the exact tumor volume, and also to protect surrounding tissue, specialised positioning devices, or masks for head and neck areas, are employed.
Small marks are applied directly to the skin, or to the mask, in order to ensure the exact same positioning and settings for each daily treatment.
In most cases the treatment field will be irradiated from many directions (multiple-field technique). The radiation emitter rotates around the patient and emits part of the required radiation dose onto the treatment field from several different directions, as specified by the radiation plan.
The entire procedure lasts a few minutes. In order to prevent side effects, the required total dose is broken up into small single doses (fractionated). For this reason a complete radiation course may last several weeks with one, sometimes two, radiation treatments daily.
By IMRT, i.e. intensity modulated radiation therapy, we are having additional possibilities to adapt the radiation dose in the target volume even more accurately. By this technique we are able to preserve sensible organs like the salivary glands optimally.