Wednesday, June 13, 2007

Fun With Radiation [C]

From 11/05-6/11/07 I've had

7 CT Scans and 4 PET Scans.

But how much radiation is that? radiation is measured in sieverts. REM/RAD is being discontinued. The sievert (symbol: Sv. millisievert = mSv) is the SI derived unit of dose. It attempts to reflect the biological effects of radiation as opposed to the physical aspects, which are characterised by the absorbed dose measured in grays. It is named after Rolf Sievert, a Swedish medical physicist famous for work on radiation dosage measurement and research into the biological effects of radiation.

1mSv = 100mrem

PET = 7mSv
CT = 10-12mSv (whole Body scan)

4 PET scans = 28 mSv
7 CT scans = 70-84 mSv
Total = 98-112 mSv

We'll go with the "low" number and say I've had 98mSv since 11/05.


Background radiation exposure in the US is ~3mSv/year.

A chest X-ray = 0.02mSv

1 CT = 500 x-rays
1 PET = 350 x-rays

So my 98mSv is 32.7years of background radiation or 4900 chest x-rays

Do you need a CT scan? Article on the abuse of CT scans for "proactive (absence of disease) diagnosis":

And of course if my previous insurance had let me get the more accurate/costly PET scans I would have had a total of 77 mSv. That's a significant reduction, 12 mSv, no? At least 600 less chest x- rays/4 years less background radiation seems significant to me.


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