Before the first session of radiation treatment, a customized plastic mask is made for the head/neck of the patient to immobilize the area to be treated.
This is followed by a CT examination while in the mask to mark tumor tissue and organs at risk.
In the head/neck region, there are many organs at risk with limited tolerance for radiation such as the:
- spinal cord
- parotid gland
- optic tracts
- brain stem
- internal ear
A uniform dose distribution over the target volume is ideal with complete avoidance of critical organs. In practice, however, this is impossible to achieve. There will always be a compromise between what is possible and desired.
Preparation for simulation which involves modeling and drawing of radiation fields takes about one week. When this is completed, the patient is ready to start radiation treatment.
Naxogin® is a drug that mimics the effect of oxygen.
Cells are three times more radiosensitive in the presence of oxygen (oxygen effect). Because of inadequate blood supply, squamous epithelial carcinomas over a few millimeters lack oxygen. A result of this is that cells in certain areas can survive radiation therapy and be a source for persistent disease or recurrence.
Radiation therapy is therefore more effective on tumor with adequate oxygen supply. Naxogin is now routinely used for radiotherapy of laryngeal cancer in Denmark and Norway.
The emetic effect of the drug, however, is a disadvantage.