IMPLEMENTATION OF VOLUMETRIC INTENSITY MODULATED ARC THERAPY IN OROPHARINGEAL CANCER. A COMPARISON WITH CLASSICAL TECHNIQUES OF 3D CONFORMAL RADIOTHERAPY

This study was performed in order to compare dosimetric parameters of volumetric modulated arc therapy (VMAT) with those of three dimensional conformal radiation therapy (3D-CRT) for oropharingeal cancer patients. We included in this study 15 patients with advanced tumours of oropharinx who had been treated in Amethyst Radiotherapy Clinic. Treatment plans were performed on a Pinnacle 3 system, version 9.4 (Philips Medical Systems, Markham, Ontario) using beam data, 6 MeV, generated by Elekta Synergy linear accelerator. The doses for planning target volume (PTV) and organs at risk (OAR) calculated both by VMAT and 3D-CRT plans were compared. The evaluation of dosimetric parameters showed a significant difference between the two techniques, especially for OAR where the received doses are higher in the case of 3D-CRT in comparison with the VMAT. Also, VMAT increases the conformity index and the minimum dose to target volumes as compared with 3D-CRT in patients with oropharinx cancer. The study confirms that VMAT is superior to 3D-CRT in the treatment of oropharyngeal cancer.