Figure 2: Flowchart showing the iterative method for biologically optimization of the intensity modulated radiotherapy (IMRT) plan described in this work. The initial FDG-PET images are corrected for partial volume (PVC) effect prior definition of the clinical target volume (CTV) and organs at risk (OAR). Thereafter, the Otsus´s method is used to segment the CTV into “j” biological planning target volumes (bPTVj). Dose prescription to each target volume (Dj) to is based on the FDG uptake and a tumor control probability (TCP) model. See the main text for a description of the parameters ,σα.,β,ρj and Vj.