Otimização física e biológica via gEUD como estratégia de redução de dose em órgãos de risco em tratamentos com radioterapia para tumores de próstata com a técnica VMAT

Abstract

The optimization of the inverse planning constitutes a primordial step in radiotherapy with intensity modulated, therefore different tools available to perform such a step in the treatment planning systems should be explored. This work compared planning optimization strategies for Volumetric Arc Therapy (VMAT) technique using DVH metrics versus use of biological function Generalized Equivalent Uniform Dose (gEUD) for the treatment of prostate tumors performed in the EclipseTM (Varian Medical Systems, Palo Alto, CA, USA) treatment planning systems, version 13.6, with the optimization algorithm Photon Optimizer (PO). This biological function is associated with the total volume of the organ at risk, dose and strongly related to parameter a. For this, 20 patients were selected and three optimization scenarios were applied, one performed without auxiliary structures for the rectum and bladder, another with auxiliary structures and finally with gEUD. Thus, it was possible to evaluate the average doses received by the risk organs in the plans and compare them, besides verifying the delivery of the treatments through PortalVision and Portal Dosimetry. It was obtained substantial reduction in the dose in organs at risk with the use of gEUD optimization tool, increased unit monitors and a higher percentage of passing the control specific quality of the patient