‘What you need is a scan’

‘What, like you have when you are pregnant?’

‘No, a CT scan, computer tomogram — that’s the only way they can really tell what’s going on — but they’ll try to fob you off with painkillers, they always do!’

My friend’s bad knee continued to be discussed in the pub, no one said she ought to lose weight, change her footwear or work on her quads.  Everyone quoted their own experiences, all were unanimous — what she needed was a scan.

That’s equivalent to 8 chest X-rays –okay, probably worth the risk.

But I went to see a gastro-enterologist recently to discuss my mild indigestion during which consultation I mentioned that a relative had died of pancreatic cancer — ‘then you had better have a CT scan!’

He reached for his pad, it was 7.30 pm, I was his last patient, he looked tired.

‘Hang on a minute — what dose of radiation will that involve me in?’

‘About 8 milliSieverts, same as about 400 chest X-rays.’  He said this very quickly, ‘equivalent to sitting at home for three years watching the telly, enjoying the background radiation.’

‘That seems a bit extreme.  I mean having a scan.’

‘Everyone has a CT scan these days, it’s the only way to be sure,’ he said, ‘I don’t mind  — you can have one.  It will almost certainly be negative but then you won’t have to worry.’

But I do worry — 3 years back-ground radiation — that sounds like I’m suddenly 3 years older — three years nearer whatever I do die of.  So I went home to wait for my appointment and looked up one or two things…

Did you know that the average person in Great Britain is exposed to 2.7mSv per year?  This is from radon in the air, radioactivity in the rocks, soil, and plants and manufactured radiation, largely medical.  The radiation in the soil  gets into plants that we eat — you can get 0.005 mSv from one little packet of Brazil nuts (135g).  My CT scan is worth 1200 packets of nuts — there’s a thought.

The background radiation is largely unavoidable and varies a bit according to where you live — radon from the ground in Cornwall gives an annual exposure of 7.8 mSv — so my CT scan is equivalent to a year in Cornwall — that doesn’t sound too bad — unless you live in Cornwall.

Radiation exposure also depends on how high you live, the nearer you are to outer-space, every transatlantic flight you take racks up 0.07 mSv (just over 3 chest x-rays or more than 5 packets of Brazils!)  If you live in Denver, Colorado (mile high city) your background radiation will be twice as much as some other places.

Tobacco  contains Polonium-210 and Lead-210, these are radioactive and become concentrated in he lungs of smokers, the US Environmental Protection Agency quote  that smoking 20 a day gives a radiation exposure equivalent to 300 Chest X-rays or  6mSv/year

Without smoking, the average person in the USA is exposed to 6.2 mSv of radiation per year, more than double the British level (unless you live in Cornwall)  If you look at the different components of these figures, most of the difference is made up by, guess what — medical radiation.

When I first visited the US 20 years ago, I saw a lot that was strange to me — shopping malls, retail parks on the edges of towns with neon signs, ice machines, burger bars and super-sized paper cups, stacks of pancakes with syrup and ice-cream and Tommy Hilfiger clothes  — all are now common-place in Britain.  From jazz and rock-‘n-roll to obesity, what starts in the US comes to us in 15 years or less.

So I guess this trend for scans will continue and I will watch the cancer rates in the US for indications of what is to come here.  In the meantime, I think I might cancel my scan because, do you know, I think I feel better.

Thanks to Panoraia Paraskeva et al for the featured image of a CT scan via Wikimedia (CC-BY-SA-2.0)

Also thanks to Public Health England for the figures for relative doses of radiation.