We have developed  special radio opaque (scanogram) radiology rulers which register clearly on an x-ray film. The rulers come in 30 and 130 cm llengths and are 38 mm wide, and are precisely engraved in 1 mm increments for accurate reading.  The finished scales come inserted in plastic pouches for protection.  A 1/4" hole above the 130 cm mark is provided for hanging when not in use. Placed next to the object being x-rayed, they make an excellent measurement tool for any radiology department.   We can also custom make the rulers to different length and width for special applications.