1. A method for localizing a fiducial marker in a medical image comprising: obtaining the medical image; determining a search window for the medical image; and performing an analysis, using an analysis unit, to localize the fiducial marker in the medical image; wherein the fiducial marker is localized by the analysis unit without use of a marker template; and wherein the act of performing the analysis comprises determining a cost function, the cost function having a component representing a rescaled grayscale intensity at a minima in the search window.