Answer to Question #418 Submitted to "Ask the Experts"

Q

What precautions are required with the use of an Oralix 50 dental x-ray machine in a lead-lined cabinet with auxilarly equipment plus 4 Kodax Ultraspeed dental x-ray film to ensure no exposure to this user?

A

From the information provided it is not possible to provide a detailed prescription of the steps necessary to insure minimum exposure to the user. It is never possible to guarantee no exposure. What is the application? What are the details of the lead-lined cabinet? How thick is the lead? How are cracks, joints, etc., shielded? The best assurance could be gained by enlisting a qualified expert to survey the machine and its environment and make recommendations for maximum radiation protection. Said qualified expert should be certified by the American Board of Radiology (in Radiological Physics), the American Board of Medical Physics, or the American Board of Health Physics. Most states now require such inspections on installation of equipment (new or used) and thereafter at regular intervals (generally no more than four years) or following any repairs that might alter machine performance. If the Oralix machine is an older model, it may be equipped with a mechanical timer that was adequate for the longer exposure times required by the slower films when it was manufactured. The timer may be neither sufficiently accurate nor reproducible for modern technology. If the application is clinical (i.e., patients or human subjects), there is no justification for use of Ultraspeed dental radiographic film. There are films now available that are at least twice as fast as Ultraspeed and which provide equal diagnostic information. If you wish to send me diagrams of the machine and cabinet I will be happy to provide further information. S. Julian Gibbs, D.D.S., Ph.D.