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Speed is an issue in the radiography of living systems, which never remain free of movement for long. The faster the screen/film combination, the less can the resultant image be degraded by movement.
In the radiography of inanimate objects, speed is not such an issue, and high resolution slow screens can be used.
Registered Member #2893
Joined: Tue Jun 01 2010, 09:25PM
Location: Cali-forn. i. a.
Posts: 2242
Oh I'm aware of that, I'm just wondering what *brands* are the brightest. If I am going to make a radiovideograph I'm going to need a bright screen and a fast lens...
Registered Member #543
Joined: Tue Feb 20 2007, 04:26PM
Location: UK
Posts: 4992
Grenadier wrote ...
Oh I'm aware of that, I'm just wondering what *brands* are the brightest. If I am going to make a radiovideograph I'm going to need a bright screen and a fast lens...
Clearly, these comparisons are given for the total receptor system i.e. branded cassette plus screens plus branded film of matching speed. If you don't put 800 speed film in an 800 rated cassette/screen combo, you will have to discover exposure values for yourself.
You'll also notice that Rarex Green Fast is considered by its makers to be equivalent to 3M's Trimax 12 (i.e. 1200 speed) but also to Kiran's KG-8 (i.e. 800 speed) so there is no exact like-for-like equivalence for receptor systems from different manufacturers. .
Now, as for your experiment, you should first determine the spectral sensitivity of your video camera, and choose between blue or green screens accordingly.
Avoid old tungstate screens if you can, because W's K energy is too high at 69.4 keV - while most of your beam energy will (I imagine) be less than this. Rare-earth phosphors such as the popular Gd2O2S:Tb3 have higher absorption in the useful 35 to 70 keV region relative to CaWO4. They also display a superior x-ray-to-visible light energy conversion efficiency.
The primary emission peak of Gd2O2S:Tb3 lies at 545 nm but emission occurs across 382-622 nm.
Actual brightness of individual scintillation events is somewhat proportional to impacting photon energy, but the perceived whole screen brightness will be dependent on both energy and fluence.
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Intensifying Screens
