Answer to Question #12820 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:


I have had an abdominal and pelvic computed tomography scan (CT). Most references cite a dose of 10 millisieverts (mSv) for this study, but in a publication on your site it says 10 mSv for an adnominal CT and 10 mSv for a pelvic CT. So, would the total dose for an abdominal/pelvic CT be 20 mSv? In my case, I asked my hospital and they said my dose was 7.5 mSv for the entire study.


You cannot simply add the effective dose from an abdominal CT scan to the effective dose from a pelvic CT scan to get the effective dose from an abdominal/pelvic CT scan. This is because there may be overlap on the two separate exams that would not occur on the one scan. Your hospital's calculation of 7.5 mSv is believable.   

Kent Lambert, CHP, FHPS

Ask the Experts is posting answers using only SI (the International System of Units) in accordance with international practice. To convert these to traditional units we have prepared a conversion table. You can also view a diagram to help put the radiation information presented in this question and answer in perspective. Explanations of radiation terms can be found here.
Answer posted on 14 February 2019. 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.