Parameter incidence on gamma index for IMRT-VMAT prostate treatment plans: The influence of MU and PTV shape

be undertaken on 12 GBM relapse patients, simulatedwithmulti-parametric MRI and re-treated with a dose-painted hypo-fractionated regime. To realise in a consistent way the MRI data extraction and the DPBN planning procedure with RapidArc or 4pi-IMRT techniques, Eclipse scripting API (Varian) and MATLAB software were realised. Results: Considering the literature (cellularity vs. ADC) and our results that correlate patient outcome to histogram change in the ADC post STUPP values, specific transfer functions (dose vs. ADC) with appropriate thresholds were reached. Dose levels (30–50 Gy/5 fr with a cumulative BED10 > 120 Gy) were estimated in an attempt to see some changes in the pattern of recurrence without causing excessive radiation necrosis (<12 Gy/fr) inside the irradiated area and respecting the previously irradiated healthy tissue (EQD2 < 100 Gy). Conclusions: The phase I/II protocol was recently approved by Ethical Committee. Preliminary data will be presented.