The radio-opacity of surgical and radiological devices used in vivo: a test method for markers in surgical gauze.

Most radio-opaque markers used in surgical gauze contain barium sulphate, and a minimum percentage content of this is required to ensure an acceptable level of radio-opacity. When this minimum percentage is specified by Standards authorities, a suitable test method must be available to determine compliance. A new radiographic test method is presented which can be used to determine the barium sulphate content or equivalence to within 2% of compliance requirements. The method consists of immersing the marker in a solution of barium sulphate which is then radiographed. Compliance can be evaluated by inspection of the radiograph. The method was found to be virtually independent of x-ray energy, film-screen combination and thickness or shape of the test object. The method is also an appropriate test for any other material or object, such as vascular catheters used in radiology or small toys which pose an ingestion hazard.