Coins As Luggage Penetrameters

I used to do alot of commercial airline travel for work, from 1999 to 2004.  Then, for about 3 years, I flew very very little, and moved to Arizona, where I flew 3 or 4 times a year for business, and once or twice a year for personal trips.  I've had my suit case x-rayed hundreds of times, in dozens of countries.  For the last dozen years, I have worked with some very skilled radiographers - x-ray specialists, who look at industrial components, looking for x-ray detectable defects.  In the last year, I've begun to work more closely with digital x-rays and have come to understand that technology more thoroughly than my previous cursory perspective. 

One thing radiographers love when they are looking at a radiograph, digital or film, is a good, clear, contrasting penetrameter.  A penetrameter helps them to know that their x-ray equipment is functioning correctly, that the object they are targeting is showing up clearly (compared to the brightly defined penetrameter beside it), and - I have found - it tends to put them "at ease".  See, without a clear penetrameter in the image, the mind of the radiographer begins to worry, to wander, to LOOK for things that maybe aren't there, or to take another image 'just to make sure'.  But WITH a penetrameter in the image, their extensive training kicks in, the human mind can make clear contrasts. These things ARE visible, and they are supposed to be, so OK, I can be less nervous, and not wonder or worry so much.  If the penetrameter is NOT clearly visible..  hmmm....  why not? What else is hiding / lurking / not visible?

So in the last 6 months, I've been INTENTIONALLY leaving coins in my luggage, in the outside thin zipper pocket, KNOWING that the luggage will be x-rayed by a TSA employee who Might or Might Not be trained very well, but who is still human, and whose eye will be Drawn To the coins, as they act as a penetrameter.  It's human nature.  And it's worked.  Since I've begun leaving the coins in, I've not been "bag checked!!!" by TSA on my roll-on bag, and if I check a bag, there's no longer the "checked by TSA" pieces of paper being left inside the suit case as there used to be post-9-11. 

In my perspective - and I've looked at 1000s of x-ray films and dozens of different metallic parts, both on film and digitally - one cannot help but look at the large shiny coin, to reflexively count the circumferential ridges, to notice the differentiation between the solid metal coin and the other objects nearby.  I am going to keep leaving a few coins in the zippered pockets, and continue to not get stopped going through security.