Monte Carlo simulation for Gamma Knife radiosurgery using the Grid

Gamma Knife radiosurgery is an established technique for the treatment of intracranial lesions and vascular malformations in the brain. In this study, dose distributions in a phantom calculated by GammaPlan have been compared with dose distributions computed by a Monte Carlo code (RAPT) assuming the phantom as a homogenous medium. Comparisons have considered both single shot plans and treatment plans. Approximately 200 radiosurgery treatment plans have been simulated using the Monte Carlo method and the initial results are discussed in this paper. The features and application of the GEMSS Grid (cluster of powerful computers) used for our computational work is described here. Analysis of the number of photons required for adequate simulation is also presented. A preliminary study of the effects of in-homogeneity has also been carried out by incorporating a 5 mm thin bone shell into the water phantom and the observed differences in the dose distribution are presented here. MATLAB software has been used to view, overlay and compare the dose distributions. A classical method of visualization of isodose lines and conformity indices has been used to compare and quantify differences. Copyright (c) 2006 S. Karger AG, Basel.