Answer to Question #11816 Submitted to "Ask the Experts"

Category: Medical and Dental Patient Issues - Nuclear Medicine and PET

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


What is the cancer risk for a patient over 65 years old having three brain 2-deoxy-2-[18F]fluoro-D-glucose (18FDG) positron emission tomography (PET)/computed tomography (CT) studies (185 MBq of 18FDG) in one year? And how does this compare to the general cancer risk in this population?


Typical effective doses for three PET/CT studies with 185 MBq of 18FDG are around 10–15 millisieverts (mSv), depending on gender and CT protocol.

Because the Health Physics Society recommends against quantitative estimates of health risks for radiation doses below 100 mSv, we will not calculate hypothetical risks for diagnostic imaging procedures. The Society's position statement "Radiation Risk in Perspective" explains in more detail why it is inappropriate to estimate health risks at these doses. Some risk information is available from

Kent Lambert, CHP, FHPS

Kaushik A, Jaimini A, Tripathi M, D'Souza M, Sharma R, Mishra AK, Mondal A, Dwarakanath BS. Estimation of patient dose in 18F-FDG and 18 F-FDOPA PET/CT examinations. J Can Res Ther [serial online] 9:477–83; 2013. Available at: Accessed 7 February 2017.

Answer posted on 8 February 2017. 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.