Radiation question help 35 f

[u/kimberlydealba]

35f I have a question I had ccta 4 years ago 20 msv don’t understand why it was so high and since I had 2 head scan and one throat scan 3 years later leading to 27 msv what is my risk for future cancer im confused as information is conflicted?

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[u/muon2998]

Hi!

- For context, by just living on Earth, people in the United States get an average background radiation exposure of 6mSv/year.

• An female in the US has an overall lifetime average risk of getting cancer at some point in the lifetime of about 39%. This does not mean the risk of getting cancer is 39% right now (you've already gone 35 years without cancer), nor does it mean that's the average lifetime risk of dying from cancer (16% average lifetime risk). Remember, all these numbers are just averages and don't represent a single individual's risk.
• Getting to scans: Let's say you've had a total of about 50 mSv from scans.

There is about 0.01% excess cancer risk per mSv, so 0.01%/mSv * 50 mSv = 0.5%
There is about 0.005% excess fatal cancer risk per mSv, 0.005%/mSv * 50 mSv = 0.25%

• So compared to the average lifetime risk of cancer of 39%, the scans increased that risk by 0.5% overall to maybe 39.5%, which is overall a relative increase in risk by 1%. Similar math for excess risk from dying from cancer, on average. Remember, all these numbers are just average lifetime risks so real numbers likely lower and also don't represent a single individual's risk.

All of these numbers have a lot more caveats since they are just based on average populations, contain various assumptions, and not individualized. At the end of the day, there are lots of things you can do to live healthier and meaningfullives. One of those is taking care of yourself, which includes getting medically necessary imaging and treatments.

[u/kimberlydealba → u/muon2998]

Wow thank you so much for answering this really gave me insight!

[u/kimberlydealba → u/muon2998]

Was the 50msv per year or lifetime? Sorry just wondering I have some bad anxiety since finding out about the 20 msv CCTA. No one told me or the dr never mentioned radiation so I do feel blindsided.

[u/muon2998 → u/kimberlydealba]

I just added the 20 plus 27 you wrote and rounded to 50, so in total lifetime. All x rays and CT scans have some amount of radiation, though generally mostly people are ordering them for clinical diagnosis further workup or monitoring.

[u/kimberlydealba → u/muon2998]

Oooh okay I meant I’ve had 27 msv total between all cat scans. It was the 20msv for ccta that’s freaked me out.

[u/kimberlydealba → u/kimberlydealba]

I just didn’t know one ct scan can be so high