The next generation MCAT: a realistic spline-based torso phantom

We develop a realistic computerized torso phantom for use in medical imaging research. The phantom has the potential to model anatomical variations and patient motion more realistically than phantoms based on simple geometric primitives. Structures are defined basing nonuniform rational B-spline (NURBS) surfaces, as used in 3D computer graphics. By fitting NURBS to patient data, the phantom is more realistic than those based on solid geometry. Points on the surfaces of the different structures in the torso except the heart were selected from the Visible Human Project CT data set, National Library of Medicine. Polygon surfaces were fit to the points for each structure and smoothed. 3D NURBS surfaces were fit to the smooth polygon surfaces. The heart model was generated with 4D NURBS as described in a previous study. The control points defining each NURBS surface can be manipulated to model anatomical variations and patient motion