Answer to Question #10462 Submitted to "Ask the Experts"

Category: Medical and Dental Equipment/Shielding — Shielding

The following question was answered by an expert in the appropriate field:

We have a C-Arm that we use for imaging patients prior to giving them radiation therapy. We are trying to find a policy for not using the spacer during exposure. Is there any regulation that speaks to C-Arm spacer use in therapeutic imaging?

The answer to your question depends on a number of items. The state that you are located in regulates the use of x-ray generating equipment. Those rules vary from state, and may or may not address your use of the C-Arm. Also, you did not indicate if your C-Arm is used for imaging or therapy simulation. Typically, rules for simulator units are not the same as for diagnostic units.

If you were in Ohio, for example, the regulations require a spacer cone on all full-size C-Arms (diagnostic imaging use) unless they interfere with the clinical procedure (this usually occurs in an operating room setting when the design of the table may knock the spacer cone off when the C-Arm is put into position). If this is the case, the regulatory body may grant an exemption to the rule if your safe operating procedure indicates that situation and there is a commitment to not allow the patient to get within 30 centimeters of the x-ray tube target under any circumstances.

Therapy simulator rules may exempt you from some of the rules that are typically in place for diagnostic fluoroscopy units.

In any case, you should review the rules from the state you are in as they pertain to your application of the C-Arm in the Radiation Therapy Department.

Kennith ‘Duke’ Lovins, CHP

Ohio Department of Health. Available at:

Answer posted on 19 October 2012. The information posted on this web page is intended as general reference information only. Specific facts and circumstances may affect the applicability of concepts, materials, and information described herein. The information provided is not a substitute for professional advice and should not be relied upon in the absence of such professional advice. To the best of our knowledge, answers are correct at the time they are posted. Be advised that over time, requirements could change, new data could be made available, and Internet links could change, affecting the correctness of the answers. Answers are the professional opinions of the expert responding to each question; they do not necessarily represent the position of the Health Physics Society.