1. A method for detecting markers within X-ray images, comprising: receiving an image sequence comprising a plurality of X-ray image frames; applying one or more directional filters to the image sequence to provide respective strength of marker features for pixels of the image sequence; determining that each of the pixels of the image sequence is a marker candidate pixel when its respective strength of marker features exceeds a first predetermined threshold value; determining which of the marker candidate pixels occur at substantially the same location within the greatest number of X-ray image frames of the image sequence; combining pixels that have been determined to be marker candidate pixels into one or more pixel clusters; computing distance between each pixel cluster with respect to each of the other pixel clusters; determining an average distance from the computed distances; defining a first marker location at a location of a pixel cluster from one or more of the clusters of contiguous pixels that includes the marker candidate pixels that have been determined to occur at substantially the same location within the greatest number of X-ray image frames; and defining a second marker location at a location of a pixel cluster from one or more of the clusters of contiguous pixels that is spaced from the first marker location by substantially the average distance.