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13 October 2008

Answer to Question #2748 Submitted to "Ask the Experts"

Category: Medical and Dental Patient Issues — Diagnostic X Ray and CT

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

What are the radiation dose and exposure risks involved in a CT of the paranasal sinuses, i.e., a CT of the whole set of sinuses around the nose, with no more specifications given by the physician requesting the CT examination? Is it comparable to what is usually designated as a "skull CT" or a "head CT"?

A CT of the sinuses is basically the same as a CT of the head. While the measured dose to the head is typically in the range of 2,000 to 5,000 millirem¹ (mrem), this exposure would correspond to an equivalent dose² of approximately 200 mrem for the entire body. A dose of 200 mrem is roughly equal to a year's worth of background radiation from continuous exposes to cosmic rays, radioactive materials present in the earth and building materials, and radioactive materials normally present within our own bodies from the food we eat. For a further explanation of CT doses, please see my answer to Ask the Experts question Q2424. It is impossible to predict what, if any, risk is associated with this level of radiation dose.

Kenneth L. Miller, CHP, CMHP
Penn State Hershey Medical Center

Editor's Notes: ¹The millirem is a unit of dose and is equivalent to 0.01 millisievert (mSv). ²The equivalent dose is calculated from the dose delivered to certain critical organs and the associated or weighted risk of cancer occurring in each individual organ.

Answer posted on 31 July 2003. The information and material posted on this Web site is intended as general reference information only. Specific facts and circumstances may alter the concepts and applications of 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 specific to whatever facts and circumstances are presented in any given situation. Answers are correct at the time they are posted on the Web site. Be advised that over time, some requirements could change, new data could be made available, or Internet links could change. For answers that have been posted for several months or longer, please check the current status of the posted information prior to using the responses for specific applications.