Answer to Question #12965 Submitted to "Ask the Experts"

Category: Medical and Dental Patient Issues

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


I had a computerized tomography scan of the abdomen with barium contrast. What is my effective dose?


The best way to estimate the effective dose is using the dose-length product (DLP) given in milligray centimeters (mGy cm). If you provide the DLP from your scan, I can calculate the effective dose. 

It's important to note that effective dose is a metric of relative risk to a population, not a dose to an individual. So, it is not your effective dose. The baseline cancer risk in the United States is around 40%, i.e., the risk of getting cancer from all sources. You don't have a 40% risk of cancer. Instead, in a group of 1,000 random people, 400 are expected to get cancer. It's a subtle but important distinction. Think about it this way: your neighbor smokes tobacco products and works in a coal mine. You exercise and eat broccoli and blueberries every day. The two of you don't have the same cancer risk, but you both are in the group of 1,000 people from which there will be 400 cancers.

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 16 July 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.