The class of deformable models has been broadly used in the segmentation of medical images. We propose a
fast linkage contour, which is guided by some simple evolution rules, to extract the boundaries of objects in
2D images. A Moving Linkage consists of links, each of which is further composed of a tail joint and a head
joint. Classified into horizontal, vertical and frozen (unmoved) types, the links are constricted on grids by the
horizontal and vertical tracks corresponding to the image pixels. Drawing an analogy between an electric current
flowing along a circuit line in the presence of magnetic fields and how it reacts in response to the force, we use
the right-hand rule to guide the motion of each link. In our approach, a small closed linkage contour is initialized
inside the region of interest. Stealing the concept of entropy conditions from level sets, the linkage contour is
easily grown, split and merged governed by some simple deformation rules. The frozen link occurs once the
speed of the free link (horizontal or vertical) is less than a specified threshold due to significant image gradients.
The deformation procedure is repeated until all links become frozen, when the linkage contour resides on the
edge of the segmented object. This new deformable model was validated by the preliminary segmentation results
regarding phantom and medical images.