http://repub.eur.nl/res/aut/47622/ List of Publications en http://repub.eur.nl/static-eur/img/logo.png http://repub.eur.nl http://repub.eur.nl/res/pub/31919/ 2002-06-12T00:00:00Z In The Netherlands. head and neck cancer (3.9%) ranks the eighth most frequemly diagnoscd malignant tumor. Radiation therapy (IIT) plays an important role in the treatmem of patients with head and neck cancer, as they constitute approximately 6% of those treated in a routine radiation therapy department. Radiation therapy can be used as a single treatment modality. but is also often combined with surgery and/or chemotherapy ( chemoradiation) in multimodaliry treatment protocols. Radiation therapy and (concurrent) chemotherapy play an important role in organ preservation protocols. The effect of ionizing radiation is unfortunately not limited to the malignant cells: it also affeers normal surrounding tissues which can lead to acute and late normal tissue complications. The head and neck region harbors organs ancl strucrures essential for basic functions, such as swallowing, speech and respiration. Preservation of quality of life (QOL) in conjunction with cure. i.e. complication-free survival. has become a key-issue in cancer treatment. ln radiation oncology the rapid technological development in linear accelerators and treatment planning systems (TPS) have significantly increased the accuracy and applicability of high doses of radiation. Highclose. high-precision RT has come with.in reach for many patients. This so called 3D conformal radiation therapy (3DCIIT) enables one to conform the dose distribution to the target volume (rumor) and therewith a better sparing (avoidance) of the surrounding normal structures is achieved. In this thesis the capabilities of 3DCIIT for sparing normal tissue structures, such as the major salivary glands. are explored. Also examples of dose-escalation wimout increased toxicity are presented. Moreover. the merit of other preventative measures to limit acute normal tissue complications. such as the use of antibiotics to eliminate severe mucositis. is reported.