X-ray scanner idea

Wolfram, Wed May 21 2008, 11:01PM

I just got an idea that I thought I'd share with the community. Feedback is appreciated. This idea is for a simple replacement for the film normally used when making radiographs.

Getting and developing film can be costly and/or expensive, and it takes time, but the results are excellent.

I have seen a couple alternatives to film for hobby radiography, but they can be a bit impractical. One way is the one that c4r0 used, photographing the front of fluorescent film from an intensifying cassette, with the X-ray tube pointed towards the back of the fluorescent film, with the object to be photographed between the tube and the fluorescent film. One problem with this is the fact that the radiation from the tube hits the camera CCD, lighting up pixels. One potential way to circumvent this would be to place some thick leaded glass, for example from the front of a CRT, between the fluorescent screen and the camera. An other way to circumvent this is to have the camera looking at the screen via a mirror, the radiation goes straight through the mirror, and therefore doesn't hit the camera. This method was used by Fabio for a real-time radiography machine he made. I'll try to find the project thread in the forum archives tomorrow.

The problem with these methods are that they can be a bit bulky, and they take up a lot of space and can be tedious to pack away if the space is needed for other projects.

My idea is to take a normal flatbed document scanner, disable the light source in it (usually a CCFL, sometimes LEDs in newer ones), place some fluorescent film from an intensifying screen where the document should go, and then sealing it so that no light can get in. The object to be photographed would be placed on top of the lid (the lid could be replaced with a sheet of black plastic if the scanner lid is too curved), the X-ray source placed above it, and then turned on while the fluorescent screen is scanned. Some scanners are very thin, so this could be made quite compact. The CCDs in scanners are usually looking at the document through a mirror, so shielding the CCD with some lead sheets in the direction where the X-rays come from should be possible.

Possible problems:

* How light-sensitive are scanners? How much light do these intensifying screens put out with a reasonable hobbyist X-ray tube from a reasonable distance? Hopefully this works out to give usable contrast.

* How long time does a modern scanner take to scan a normal page at a reasonable resolution (100-200 DPI)?


Anders M.