This paper presents a modified-octree technique that generates a mixed-element mesh. The final output mesh consider cubes, prisms, pyramids and tetrahedra. This technique is optimized for brain tumor extraction simulation in a real-time application. The proposed technique is based on the octree algorithm with a specific constraint: elements will be split only if they intersects a certain region of interest. With this approach we pursued a refined mesh only in the path from the skull opening point to the tumor. Fast computation by the Finite Element Method (FEM) is achieve thanks to the local refinement. Examples are given and comparison with other approaches are presented.