Initial experience of hypofractionated radiation retreatment with true beam and flattening filter free beam in selected case reports of recurrent nasopharyngeal carcinoma

Aim: To show our preliminary experience in using TrueBeam with RapidArc technology and FFF beam for stereotactic re-irradiation of nasopharyngeal carcinoma. Background: Thanks to new advanced techniques, as well as intensity modulated radiation therapy, it is possible to approach head and neck recurrences in selected patients. Volumetric Modulated Arc Therapy (VMAT) in its RapidArc^® format, permits to reduce significantly the time to deliver complex intensity modulated plans, allowing to treat hypofractionated regimes within a few minutes. With TrueBeam it is possible to perform photon beams without usage of the flattening filter. It seems possible to expect a reduction of out-of-field dose when flattening filter free (FFF) beams are used. While research into the physics domain for FFF beams is increasing, there are very few clinical data where FFF beams are applied in clinical practice. Materials and methods: We present here the cases of 4 patients with local or regional recurrence of nasopharyngeal carcinoma. All patients were treated using TrueBeam with RapidArc technology and FFF beam for stereotactic hypofractionated re-irradiation. Results: All patients concluded SBRT and showed good tolerability. During follow-up, complete response at imaging evaluation (PET and/or MRI) for all treated patients was documented. Conclusions: Our preliminary experience using TrueBeam with RapidArc technology and FFF beam for stereotactic hypofractionated re-irradiation of nasopharyngeal carcinoma was safe and effective in all 4 treated patients. Longer follow-up and a larger population of study is needed to confirm these promising results.