Fun with X-Rays

I took my father to the shops today to buy a couple of pairs of shoes. At 93 years old he's (perhaps wisely) given up driving. We went to the same shop he's been going to for decades and knows the owner and his family.  

It's an old fashioned shop and I have an early memory of going there for shoes as a child in the mid '60's. I loved the shop because of a machine they had - a shoe fitting fluoroscope. This was an American invention but a version, the Pedoscope, was made in this country between the 1930's and mid '50's.   

This was, believe it not, a self operated X-ray machine. It was a timber box with a space at the bottom for your feet and viewing screen on top where you could see the bones of your feet inside the shoes. It was a novelty device, a sales gimmick. You don't need an X-ray to know whether your shoes fit.  

"It's a good idea" - maybe not.

The label at the top reads "This machine fully conforms to Home Office safety requirements and in normal use is unconditionally guaranteed as safe".   

 

I guess that the X-ray source was a Crookes tube, a type of cathode ray tube that uses high voltages to produce high energy (ie very fast) electrons that produce X-rays when they hit the end of the tube. These rays pass through the foot and were made visible by a fluorescent screen.   

My don't think my mother knew much about physics but she certainly didn't like us using the machine. And she was probably right. Allowing children (or anyone else) unlimited exposure to ionising radiation was a known cancer risk by the '50's. I guess the machines will have disappeared by the end of the '60's.  

They were also not good for the shop staff. Although the X-rays were intended to be restricted to the machine but the shielding was suspect and the whole shop was likely flooded with X-rays.