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Radiology/Calculating mSv and mGy.



My name is Bruno Barreira, and I am contacting you in hope to clarify, or at least obtain some information about the future of my life's health.

I have been exposed to Ionizing Radiation recently, I'm 25 years old from Portugal and recently I've been diagnosed positively for Ischemic heart disease in a stress test, weird right?
I'm not obese, my weight is 65kg and 1.81m, never smoked, and live in a radiation free area, the radon levels are very low also.

I've consulted three doctors and all of them wanted me to do a Coronary CT Scan, one that emits the most quantity of radiation. I've done the test, and everything came back fine, it was a false positive.
Problem is, I've been researching many articles how ionizing radiation is harmful, and that hormesis is not real or not proven.

Currently I am very scared that in 10-20 years I might develop lung cancer or heart related problems, I am aware that is very likely that something might happen, and I regret the day I took that unnecessary scan.

I've attached my patient protocol file that I've requested at the hospital, it gives me the values of the radiation dose I've took. I've also asked the doctor to calculate in mSv the dose I took, he said 5.88mSv, then
I asked another doctor over the internet and he gave me a 5.5 mSv value.

Do you know if those values are correct? I don't know how to convert those values into mSv or mGy.

Thanks in advance.
Bruno Barreira

Hello, Bruno.

First, I do not know if the exposure values are correct because I don't deal with ionizing radiation any more. If you'd like another opinion about the dose, a radiologist or a radiation therapist would be the best ones to ask.

Let's use the values you do have and presume that your radiation dose from the Cardiac CT was 5.5 - 5.88 mSv. This value is comparable to the normal dose you'd receive from background radiation over 2 years. The additional lifetime risk of fatal cancer from this examination is low. For more information on this, see:

Here is another great site for answers about radiation exposure:

It's always a good practice to minimize your exposure to ionizing radiation whenever possible. In medical imaging, the benefits of having an image should outweigh the risks of exposure. Next time an x-ray is ordered, ask your doctor whether the results of the exam will determine the treatment of the injury. If treatment would be the same whether there is an x-ray or not, minimize your exposure & decline to have the x-ray.

I hope I've been able to allay your fears about developing cancer from this one study. Though possible, it is highly unlikely.

Best Wishes,
Delia White
Santa Barbara Extremity MRI  


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Delia White


I am not qualified to interpret diagnostic imaging or to diagnose disease. Please consult a physician for that information. I am the photographer. I can tell you what to expect during most MRI, CT and X-ray procedures.


I now have more than 30 years experience in diagnostic imaging. My specialty is MRI. I am also very familiar with CT and the way we used to take x-rays (everything's digital now)!

I received my Bachelor of Science degree in Radiologic Technology.

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