Using Monte Carlo Simulated Radiation Transport To Calculate Dose Distribution In Rats Before Irradiation With Leksell Gammaknife?

Denis Porcheron1, Béatrice Marcelin2, Per Kjäll1, Jonas Johansson1, Anders Lundin1, Håkan Nordström1, Markus Eriksson1, Christophe Bernard2, Jean Régis2

1Elekta Instrument AB, Stockholm, Sweden 2INSERM-U751, Université de la Méditerranée-Service de Neurochirurgie Fonctionnelle et Stéréotaxique, Hôpital La Timone

Keywords: Monte Carlo, dosimetry, gamma knife, Dose distribution, physics

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     Gamma Knife Surgery (GKS) is used with subnecrotic doses for temporal lobe epilepsy (TLE) treatment. Rat models of TLE have been used to probe the mechanisms underlying GKS.
     The irradiation time to achieve the dose to deliver was determined with the Leksell GammaPlan® (LGP) treatment planning system. Since LGP is not designed for such small structures, it is important to calibrate the system for the rat brain.
     We have used a Monte Carlo Simulation (MCS) radiation transport scheme, with CT-data as anatomical and tissue specific information, to simulate the dose distribution in a rat brain when using Leksell GammaKnife® (LGK) as the irradiation unit.
     We show how dose distributions obtained from MCS quantitatively compare to those predicted by LGP, and we discuss when LGP can and cannot be used for rat studies. The energy deposited, when using the 4 mm collimators, was calculated for targets on both sides of the brain in the dorsal hippocampus, which allowed us to determine the exact time to use to irradiate rats with a given dose.
     This is a retrospective study.
     The MCS method used in this work can easily be used for future GKS studies on rats when accurate dose distributions are required.


Project Roles:

D. Porcheron (), B. Marcelin (), P. Kjäll (), J. Johansson (), A. Lundin (), H. Nordström (), M. Eriksson (), C. Bernard (), J. Régis ()