The application of adaptive radiotherapy in re-radiation of the head and neck cancer — description of the method based on the first clinical experiences in Poland

Introduction. Adaptive radiotherapy in head and neck cancer is innovative, accurate and useful method of treatment, especially in re-radiation cases. This approach allows precise dose distribution in target volume and minimizing exposure in healthy tissues. Material and methods. We present one of the first experience of adaptive radiotherapy in Poland in head and neck cancer patient diagnosed with second primary cancer in the previous irradiated area and treated to a total dose of 36 Gy in 9 fractions. Results. Logical unions of the planning target volumes (PTVs) (8.2 cc–12.9 cc) and larynx volumes (68.7 cc–80.1 cc) obtained on the basis of contouring before every adaptive radiotherapy fraction indicate the variability of the tumor and organ at risk position. The volume of the isodose (3.9 Gy) covering the target was 11.9 cc–16.3 cc. The maximum dose to the larynx during radiotherapy ranged 4.06 Gy–4.18 Gy, and was lower than the maximum dose within the union of the larynx volumes 4.38 Gy–4.43 Gy. Conclusions. The use of adaptive radiotherapy allows for accurate dose delivery and avoids migration of critical structures into high-dose regions.