The invention relates to a real time radiation treatment planning system for use in effecting radiation therapy of a pre-selected anatomical portion of an animal body using hollow needles. According to embodiments of the invention, the system may include a processing means processing means-configured to perform a three-dimensional imaging algorithm and a three-dimensional image segmentation algorithm, with respect to one or more specific organs within the pre-selected anatomical portion and with respect to the needles, for converting the image data obtained with an imaging means into a three-dimensional image of the anatomical portion, using at least one single or multi-objective anatomy-based genetic optimization algorithm. For pre-planning or virtual simulation purposes, the processing means is arranged to determine in real time the optimal number and position of at least one of the needles, positions of energy emitting sources within the needles, and the dwell times of the energy emitting sources at the positions. For post-planning purposes, the processing means is arranged to determine, based on three-dimensional image information, in real time the real needle positions and the dwell times of the energy emitting sources for the positions.