X-Ray Camera

[sandiii]

Hi,

I want to take some digital radiography pictures with a used dental x-ray head (60kV)

is it possible to take a radiography picture of an intensifying screen directly with a small webcam protected by lead glass in one line to the x-ray source or should I try to use a mirror with an angle of 45 degrees to protect electronics from x-ray radiation?

Greetz and sorry for my (eventually bad) english
sandiii

[mikeselectricstuff]

Unless you already have some lead glass, a mirror is probably the easiest, though you may still get some scattered x-ray noise.
A webcam is probably not an ideal choice as you will want to take long exposures of a few seconds, so a camera with full manual controls and remote operation, like DSLR, will be a lot better.
Resolution with a dental tube is probably not going to be enough to need a state-of-the-art SLR, so an old lower-res used model should be fine.

[Wolfram]

Seconding the recommendation for a DSLR, a second advantage is that SLR lenses often have enough glass thickness internally to shield scattered x-rays and even direct x-rays at lower tube voltages. The first attached picture was taken with a DSLR in the beam path of a dental x-ray head at 80 kVp half wave rectified, with no mirror and no lead glass. Some hot pixels are visible from x-rays hitting the sensor, but the overall noise level is pretty low.

Resolution with dental tubes can be surprisingly good, if the object being imaged is kept close to the screen or film. When comparing radiography done with a screen and a digital camera with direct film radiography, I never managed to get close to the resolution of film using fluorescent screens and digital cameras, all using dental x-ray tubes. This indicates that the source focal spot size is not usually the limiting factor when it comes to sharpness in a setup like this. An example image taken using a dental x-ray head with a 0.7 mm focal spot is attached. Focal-spot-to-object distance was approximately 50 cm and object-to-film distance was around 5 cm. The film used was Agfa Structurix D5, 15 second exposure time at 70 kV DC, 4 mA.

[John Heath]

Wow , great pictures. What are the 1 to 10 K volt range photons like for x-ray pictures?

[cdev]

Really beautiful.

What kind of sensor do you use for the digital images?

Is it just a flat CCD inside of a flat enclosure?

[sandiii]

It's not really a webcam - i thought about using a Raspberry Pi Camera Module for imaging. They have 8MP and you're able to control shutter speed, ISO-level and so on.
Additionaly the Raspberry could control my X-Ray head.

And I already have some lead glass (diameter 90mm, thickness 10mm). You'll find it on ebay for small money

[Wolfram]

1 - 10 keV photons are pretty useful for x-raying non-dense objects, such as paper, flowers and insects. Most denser objects will attenuate the x-rays to such a degree that it is difficult to get a meaningful picture. Note that these x-rays don't pass through the glass envelope of common glass x-ray tubes. Beryllium window tubes are reasonably common, and a typical ~100 µm x-ray tube beryllium window will transmit x-rays down to an energy of around 3 keV.

More info on flower x-rays here: http://pubs.rsna.org/doi/full/10.1148/rg.235035045 .

For the digital images I used a screen from a mammographic x-ray cassette (Kodak Min-R IIRC) and an old Nikon D70 with a Sigma 50 mm F/2.8 macro lens. Mammography cassettes have a higher resolution (and a lower light yield) compared with the cassettes used for general radiography. I am sure much better results can be had with a modern camera and a more sensitive lens.

The black-and-white image was captured on Agfa Structurix D5 film, developed and scanned on an Epson V700 flatbed scanner.

It's not really a webcam - i thought about using a Raspberry Pi Camera Module for imaging. They have 8MP and you're able to control shutter speed, ISO-level and so on.
Additionaly the Raspberry could control my X-Ray head.

And I already have some lead glass (diameter 90mm, thickness 10mm). You'll find it on ebay for small money

It sounds like a worthwhile experiment, especially if you already have the parts. It will work for sure, and if you want to improve the resolution or sensitivity later, you can look into fancier cameras and optics.

[mikeselectricstuff]

The black-and-white image was captured on Agfa Structurix D5 film, developed and scanned on an Epson V700 flatbed scanner.

Was that just film, or with a scintillator plate ?

[Wolfram]

The black-and-white image was captured on Agfa Structurix D5 film, developed and scanned on an Epson V700 flatbed scanner.

Was that just film, or with a scintillator plate ?

That was just plain film, without any intensifying scintillators or foils. Using a mammographic cassette would probably have reduced the exposure time by a factor of ten or twenty at the likely cost of some reduction in sharpness.