Evaluating the impact of anatomical changes on dose distributions in head and neck cancer

Abstract Introduction: Thanks to modern IGRT procedures, it is possible track changes in the patient's anatomy and thus calculate dose distribution for current anatomical conditions of patient. This allows scheduled be compared with delivered dose. In case large discrepancies, improve treatment plan. Radiotherapy, during which plan modified, resulting from anatomy, referred as adaptive radiotherapy. Material methods: study was performed 30 patients H&N cancer at University Hospital Zielona Góra. All were treated VMAT. The Simultaneous Integrated Technique used. each session, set-up verification performed. Alternating every other day, CBCT two orthogonal portal images made, position correction prior session For all patients, new planning CT made after 11th 22nd sessions. Dose distributions initial on CT11 CT22 calculated. dose-volume histograms DVH0 DVH11 DVH22 calculated CT22. Results: We CTVs most important organs risk obtained CTs second fourth week irradiation. differences between mean doses V95% GTV small. a few CTs, values smaller by more than 5% points. salivary glands increased treatment. Conclusions: Anatomical occurring radiotherapy head neck cancers have little influence deposited Clinical Target Volume. Adaptive therapy may particular importance if relapse occurs re-irradiation.