- Nov 25, 2008
I frikkin love HV, it's so unpredictable :crackup:
Very interesting. Have you any idea what it is putting out. X-Ray techs of course prior to automation though in Kv and MAS....technique calculations for a particular type of X-Ray and patient weight.
How many rem or sieverts are you getting with this little device?
When I was a kid my parents had this doc with his own fluoroscope. It had a phosphor plate which moved over the body in concert with the x-ray tube that moved behind the body part being viewed. These machines put out quite a lot and were eventually taken off the market.
How much did this cost you. I once though about doing something like this but I was concerned about exposure.
As I re
That link doesn't work. Either way though, a dosimeter is only a dosimeter if it is calibrated and certified for the specified radiation source in question. Unless that links to a $$$-$$$$ ion chamber survey meter, scintillator probe, or badge system it isn't appropriate.
I cannot stress enough how dangerous an X-ray source is, even a small one. Depending on specifics of unit they can be lethal in as little as 10minutes of exposure. Adequate shielding, proper detection equipment, safety protocols, and remote operating systems are not optional.
Fwiw my project cost about $250 total, but I waited for a deal to happen to keep costs down.
When you say that ten minutes of x-rays can kill, what do you mean?
It takes about 30 gy (or in my archaic thinking 3000 rads to immediately destroy neurological tissue.
Having a very small source as in what you have it would depend upon where the dose was absorbed and it would not be immediate. Gut endothelial tissue is the most sensitive that is whay acute radiation sickness manifests in nausea and diarrhea Then you have effects upon bone marrow and RBC production. However, WBCs are suppressed and death is by infection. Large doses as you know can effect skin.
Do you have any idea what he maximum amount this could be putting out.
Addition, as you know, the tube does not have any collimation and is just shooting out in some large pattern.
If you are actually in another room, I doubt your are receiving anything.
Sig, I saw the pics. They are really good. How big are your cassettes? What film are you using? What do you mean by camera. I thought you were putting your objects directly in front of the objects...x-rays pass through...then hit the cassette/phosphors....and you get an image?
How are you regulating exposure. My frame of reference is a garden variety old x-ray machine using a bucky....and changing MAS and Kv.
Cassettes are 18cm x 24cm. The imaging setup I am using is filmless. I have a Micro-4Thirds Mirrorless system camera directly imaging the fluorescence of the X-Ray Intensifier Screen. From left to right it is X-ray source, 2cm space, light-blocking shielding (cardboard), 13cm space, target item to be imaged, x-ray cassette OPEN - front screen (tube side marked), 1 meter space, camera pointed at screen.
As for regulating the image exposure I have determined approximate luminosity of the screens in terms of camera settings (ISO speed, aperture size, exposure length in Seconds) needed to get a perfectly exposed full-transmission area and a perfectly dark full-radio-opaque area. I then simply match the beam-on time with the needed camera exposure time.
If I want to adjust the x-ray hardness I can use the impedance curve of the HV supply as a means of adjusting the peak voltage by increasing or decreasing the tube impedance via the filament voltage. I outlined the basics of this in my blog post write up. I don't in practice need to adjust the hardness very much though because of system limitations. If I wanted to image very low density objects I have a rather large leeway in just post processing and exposure time. However I could reduce hardness if needed there too. As far as increasing hardness, I run the setup at near maximum hardness usually. If I need to image denser objects and have a greater degree of transmission I can increase x-ray exposure time, decrease camera sensitivity, and change the pixel curve in post processing. I successfully demonstrated this in the last batch of images actually, though I only posted one of them. The image with the two flashlight and two flash drives; Just a single exposure I can actually adjust the pixel values in post to where the plastic of the flashdrives is fully visible, or to where there's good definition of the batteries within the thick flashlight hosts but the plastic of the drives is totally invisible. This, along with the elimination of having to actually handle and develop film, is the largest benefit to the digital technique.