an x - ray marker includes a shaping material formed with a base having a substantially constant thickness and pattern formed in the base having a thickness different than the base . an x - ray attenuator is suspended in the shaping material creating a composite material having a substantially uniform density . the x - ray absorption of the base varies in proportion with the base thickness . therefore , the different thicknesses of the base forms an image corresponding to the pattern when the marker is disposed over an x - ray sensitive image receptor and exposed to x - rays .