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Registered Member #1225
Joined: Sat Jan 12 2008, 01:24AM
Location: Beaumont, Texas, USA
Posts: 2253
I have been wondering what kinds of phosphors would fluoresce in X-rays. With phosphors that fluoresce in the presence of X-rays, it would be simple to make a simple fluoroscopic screen for fluoroscopy.
I am not sure what chemicals/phosphors that are fluorescent in whatever wavelength of light there are, and i have no money to buy such things. That being said, i do have a bag of phosphors from televisions, and i could easily obtain phosphors from a fluorescent bulb.
I know that TVs contain ZnS-based phosphors, but i am not sure about fluorescent bulbs. Are they virtually the same? Also, the phosphors from the TV i have are all mixed together... It would still fluoresce just as well, just with mixed colors, wouldn't it? Would either Phosphor fluoresce well enough in the presence of X-rays to make a fluoroscopic screen?
Edit: Aha, after even more googling, i found this study regarding "Evaluation of ZnS:Cu phosphor as X-ray to light converter under mammographic conditions".
In the PDF, it states "This phosphor has never been used in medical imaging probably due to its moderate scintillation decay time. However, it may be suitable for non-dynamic medical imaging, due to its “green†emission spectrum, which is compatible with the sensitivity of many currently used photodetectors, and its high X-ray to light intrinsic conversion efficiency.", and that it performs adequately in the power range of mammography. So, it seems it may work, if the phosphors i have are similar enough to those the people in the study used. Scintillation decay time would be the least of my worries, especially considering i would not necessarily use it on anything moving (definitely not myself!)
Registered Member #33
Joined: Sat Feb 04 2006, 01:31PM
Location: Norway
Posts: 971
Older screens used in x-ray cassettes were based on CaWO4, while modern one are based on rare earth doped oxysulfides, most commonly Gd2O2S:Tb. These phosphors are far better at this than any phosphor you might be able to get cheaply in powder form. Getting a powder into a uniformly coated sheet might be a bit of a challenge too, to put it mildly.
X-ray cassettes are widely available on eBay (and they are dirt cheap, here is one for 4 dollars, and in lots they tend to go even cheaper, I've bought lots for around a dollar a piece). Each cassette contains two screens (except for mammography cassettes).
These screens are an order of magnitude better than anything that can be made at home without very expensive phosphors and equipment. Making a fluoroscopy screen yourself would be a bit like making toilet paper yourself, possible, but there are cheaper, simpler and better alternatives. Unless, of course you just want a challenge and not results.
Registered Member #1225
Joined: Sat Jan 12 2008, 01:24AM
Location: Beaumont, Texas, USA
Posts: 2253
It is mostly just a challenge, yes :). I have 100 5"x12" green sensitive panoramic X-ray films, and the developer and fixer, so i will be needing a cassette, if i want to take good X-rays.
Not to mention, i am not sure if it is possible to get a cassette, due to the fact that my parents will not allow me buying off of eBay, because of someone stealing 3000 dollars from the credit card... It's a shame, eBay is the only way for me to get some of the things i will need :/.
Registered Member #543
Joined: Tue Feb 20 2007, 04:26PM
Location: UK
Posts: 4992
A small British company, Phosphor Technology, stock a range of X-ray phosphors, including zinc-cadmium sulphides in addition to the usual rare earrth oxysulphides.
I am experimenting at the moment in the electrochemical deposition of thin ZnS films onto tin oxide glass, and will have more to say about it in a month or so.
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X-ray sensitivity of phosphors.
