Image guided high-dose-rate brachytherapy versus volumetric modulated arc therapy for head and neck cancer: A comparative analysis of dosimetry for target volume and organs at risk
Background. To present dosimetric comparison of image guided high-dose-rate brachytherapy (IGBT) with volumetric modulated arc therapy (VMAT) for head and neck cancer regarding conformity of dose distribution to planning target volume (PTV) and doses to organs at risk (OARs).
Patients and methods. Thirty-eight consecutive patients with T1-4 mobile tongue, floor of mouth and base of tongue cancer treated with IGBT were selected. For these patients additional VMAT treatment plans were also prepared using identical computed tomography data. OARs and PTV related parameters (e.g. V98, D0.1cm3, Dmean, etc.) were compared.
Results. Mean V98 of the PTV was 90.2% vs. 90.4% (p>0.05) for IGBT and VMAT, respectively. Mean D0.1cm3 to the mandible was 77.0% vs. 85.4% (p<0.05). Dmean to ipsilateral and contralateral parotid glands was 4.6% vs. 4.6% and 3.0% vs. 3.9% (p>0.05). Dmean to ipsilateral and contralateral submandibular glands was 16.4% vs. 21.9% (p>0.05) and 8.2% vs. 16.9% (p<0.05), respectively.
Conclusions. Both techniques showed excellent target coverage. With IGBT dose exposure to normal tissues was lower than with VMAT. The results prove the superiority of IGBT in the protection of OARs and the important role of this invasive method in the era of new external beam technologies.