RESUMO
PURPOSE: Measurements and Monte-Carlo simulations were carried out to model the dose distribution of a prototype electron beam linear accelerator (Kinetron LINAC) to determine the dose to organs in small animal irradiations experiments. Dose distributions were simulated using the GATE8.0/Geant4.10.3 Monte-Carlo platform, and measured in air and solid water phantoms using a commercial scintillating screen detector and new EBT-XD Gafchromic films. METHODS: The LINAC is able to produce 4.5â¯MeV electron beams at dose-rates ranging from Gy/min to thousands of Gy/s, and is used to study the radiobiological effects of very-high dose-rates that have been shown to protect normal tissues from radiation toxicity. Numerical simulations and experimental dosimetric characterisation of this electron accelerator were performed with the Monte-Carlo toolkit and various detectors. Absolute dose distributions in solid water were measured and compared with simulations. Realistic electron irradiation conditions were simulated in voxelised mice CT images. 3D dose distributions and dose-volume histograms in lungs of mice were simulated and analyzed. RESULTS: Measured and calculated depth-dose profiles for several beam configurations (energy and dose-rate) were compared. Beam emittance was validated by comparing measured and calculated beam sizes along the central axis in air: the deviation for all conditions was less than 1â¯mm. A good agreement was obtained between experimental dose distributions and the results obtained with simulations (<2% dose differences for lateral and depth-dose profiles). CONCLUSIONS: The method presented here, relying on few free parameters, can be adapted to very-high dose-rate electron irradiation to support the analysis of preclinical research experiments.
