Tubing having a smooth inner bore and a smooth even outer surface wherein the properties of X-ray opacity and optical permeability are optimized and maximized by forming the tubing from a plastic and an X-ray opaque substance homogeneously dispersed in the plastic wherein the X-ray opaque substance has a controlled concentration and an index of refraction as close to the index of refraction of the plastic as possible; additionally where the plastic forms crystalline structures it is not annealed during the fabrication of the tubing to further optimize optical permeability of the tubing.