A method for determining the concentricity of a golf ball having a barium or bismuth doped boundary layer or cover is disclosed herein. The method uses an X-ray imaging machine to determine the thickness of the cover at various locations to ensure concentricity of the golf ball. The boundary layer may be an ionomer blend doped with barium or bismuth in an amount of five to fifteen parts per hundred of the ionomer material, and the cover may be composed of a thermoset polyurethane material. Alternatively, the cover may be doped with barium or bismuth, and the boundary layer may be undoped.