Contribution of in-vivo dose measurement on intensity modulated radiation therapy technique in head and neck cancer treatment

Nasopharyngeal cancer treatment plan was established for the human equivalent build model (Rando Phantom) by using the technique of Intensity Modulated Radiotherapy (IMRT) with Elekta Precise treatment planning system. The feasibility of in-vivo dose measurements in IMRT technique and contribution to the quality control of treatment were studied using a model of human-like structure. CT images of the human equivalent structural model were obtained with Generel Electric (GE) brand Light Speed RT model computed tomography (CT) device. Then target and organs at risk were drawn manually on CT images for IMRT plan. Following the establishment of IMRT plan in treatment planning system with 6MV energy and evaluation of radiation doses, suitable locations were determined for dosimeter. Dosimeter type was chosen in accordance with designated points inside and outside of the treatment volume. Calibrations of thermoluminescence and semiconductor dosimeters used in the measurements were performed. IMRT plan was applied to the human equivalent build model by utilizing Elekta brand Synergy model linear accelerator treatment device. Dosimetric measurements were performed for each dosimetry types and dose data were acquired. Radiation dose data were compared with the calculated data acquired from the treatment planning system. For in-vivo dosimetry appropriate positions for Planning Target Volume (PTV) and organ at risk were identified and dose measurements were found to be at acceptable levels. Dosimetric studies within the scope of the thesis were carried out at the Akdeniz University School of Medicine Department of Radiation Oncology.