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
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