INVESTIGATION OF IMMOBILIZATION METHOD WITH PORT FILMS IN HEAD AND NECK CARCINOMA PATIENTS

Radiotherapy is one of the main therapy modality in the treatment of head and neck carcinoma patients. Treatment of tumours with radiotherapy necessitates the irradiation of the same target volume. For immobilization, many different techniques have been used. In the Radiation Oncology Department of Dokuz Eylül University Medical School, a material (ORFIT) which is easily shaped under low temperature water is used. Twenty patients have been treated between May, 1992-June, 1992, simulation films and port films which were taken at the same Focus Skin Distance with this system during the treatment were compared with regard to field dimensions and the chosen reference points. The differences between the field dimensions is in the range of 0-20 mm with an average of 7.6 mm. Deviation between the reference points is median value of 13.5 mm and average value of 13.54 mm. To improve the quality assurance in radiotherapy immobilization is essential. Despite the use of immobilization methods, differences may occur in the treatment planning. In defining target volume, practical conditions should be taken into account and the factors which could effect the precision of simulation planning should be checked.