A method and corresponding system for calculating an optimum surgical trajectory or path for displacing a surgical instrument through the interior of the body of a patient. Upon obtaining a volumetric scan of a patient, such as a CT scan, the surgeon can identify and assign weight values indicating a preference on whether an anatomical area be utilized in plotting an optimum instrument trajectory. Upon providing a starting and destination point for a surgical instrument, an optimum surgical trajectory can be determined in essentially real time and graphically presented to the surgeon by superimposing the proposed trajectory upon the patients volumetric scan. Furthermore, the system and method is interactive, allowing the surgeon to deviate from the proposed optimum path if desired and choose another path. In response, the system will determine and present, in essentially real time, a new optimum trajectory based on the current location of the surgical instrument.