FIRST RESULTS ON IN VIVO TLD DOSIMETRY IN BRACHYTHERAPY OF HEAD AND NECK CANCER PATIENTS

In vivo dosimetry in brachytherapy is one of the most challenging procedures in the praxis of experimental patient dosimetry. Due to the specific brachytherapy treatment procedure it is possible to insert the dosimeters via catheters directly into the cancerous tissues or into the body cavities in the nearest vicinity of the organs and tissues of interest. In this paper we provide some results on the dose evaluation in High Dose Rate (HDR) interstitial brachytherapy of Head and Neck cancer patients using two types of micro dosimeters: "pin worms" and TLD - 100 microrods. This type of brachytherapy treatment is based on the patient's irradiation when the radioactive Ir-192 source moves inside of the 6F catheters preimplanted in the tumor and stops at the prescribed positions to irradiate the tumor. An extra empty F6 catheter was implanted into tumor volume for dosimetric purposes. Micro TLDs were arranged in train sequences and were inserted into 6F catheter to measure absorbed patient doses during brachytherapy procedure. The results of experimental in vivo dose measurements are compared to those obtained using a standard dose calculation algorithm of brachytherapy dose planning system. Evaluated dose discrepancies are discussed on the basis of the obtained results.