First of two dental x-ray generators

[klugesmith]

A week before Covid lockdown, a local dentist was moving to a new office.  He didn't have to move his oldest x-ray machine, because I took it off his hands.

The control box reflects my interests and image. It includes a switch-selectable autotransformer, timer, and long curly cord with remote-control button. Output had been wired to an ordinary wall outlet into which the X-ray head was plugged.

Wires were cut and plugs were removed to get the machine home.  Control box wires were restored a couple weeks ago, and tested by turning on a desk lamp for selected short intervals and selected brightness.  Then X-ray head joined the party, not to make radiographs but to measure the expected bursts of ionizing radiation.

It worked on the first try, and the next 10, all with me about 20 feet away, before all four 200 mR pen dosimeters were near full scale.

Note well: if timer and dosimeters are accurate, the point-blank intensity was around 300 to 500 R/hr.  A seriously scary level if seen on a regular Civil Defense meter.

These systems have a mechanical hazard which could be lethal if overlooked. The manipulator pantograph, like many adjustable drafting tables and garage door openers, includes strong springs instead of counterweights. Unless restrained, a linkage can clobber you unexpectedly when a load is removed, or a brake or clamp is released.
Springs can beat high voltage capacitors, when it comes to storing energy for years with no loss.

[klugesmith]

Finally used that thing to make a couple of radiographs.  My fluorescent screens are lost in clutter, and wet film developing too much trouble.  So I ordered some self-developing dental film packets, with a standard size about 31 x 41 mm.  Started with exposure tests using some well-defined phantoms arranged on a piece of sticky tape in a frame.  1 to 5 layers of 4 oz copper foil, and 1 or 2 layers of round aluminum wire (avoiding aluminum alloys).  Some radiolucent objects like a thickness wedge of aluminum foil and a thin Lego brick are barely detectable in the second image.