Answer to Question #7569 Submitted to "Ask the Experts"

Category: Medical and Dental Equipment/Shielding — Equipment

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

Do you have any data on dose to health care workers who stand next to CT (computerized tomography) machines during studies or dose rates near a CT machine? I know this would be machine dependent, but any information would help.


Data that we have acquired from various models and vendors of CT scanners indicate exposure rates on the order of 5.16E-4 Coulomb/kg/hr approximately one meter from the center of the gantry. This is measured with a head or body phantom, scanned using typical patient technique factors, in an axial scan mode. As you stated, these can be very vendor-specific and depend on the actual geometry and the survey instrument used. I recommend that you consult vendor-supplied isodose curves diagrams for expected dose rates by manufacturer and model. I also recommend that you consult with medical physicists who test the equipment in question for their input on the exposure rates that they measure.

Kennith "Duke" Lovins, CHP

Answer posted on 28 May 2008. 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.