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Up Topic Welding Industry / Inspection & Qualification / Digital Radiography
- - By PlasmaHead2 (***) Date 11-19-2008 00:51
Hello all,
I'm wondering about how it works. I went to the dentist the other day and instead of the film to take X-rays they used a little box hooked up with wires that sat next to the teeth.
Seconds after the shot the image showed up on a computer screen right in the room.
Do you RT guys get to use anything fun like that or are you all limited to film still?

Curious,
-Clif
Parent - - By fbrieden (***) Date 11-19-2008 01:56
I had that done and my lower jaw fell off!!!
Parent - - By Jim Hughes (***) Date 11-19-2008 12:50
PlasmaHead2,

Digital radiography is a form of x-ray imaging, where digital X-ray sensors are used instead of traditional radiographic film. Advantages include time efficiency through bypassing chemical processing. Don't have to worry about chemical spills and have to deal with the enviromental dude on the project. Another advantage is the ability to digitally transfer and enhance images. Also less radiation can be used to produce an image of similar contrast to conventional. You get all this information just like you witnessed in the dentist office. You don't have to worry about checking density. You can send the image via e-mail to your level III for review if needed. The safety exclusion zone around the work is less than traditional RT.

Hope that helps
Jim
Parent - By PlasmaHead2 (***) Date 11-19-2008 22:47
Jim,
Yes, that explained what I was wondering about. Thank you for your time.
Parent - - By PlasmaHead2 (***) Date 11-19-2008 22:55
Is that why you hide on the forums so much fbrieden? ;) :) :)
Parent - - By Superflux (****) Date 11-20-2008 12:26
The only downside I've heard concerning digital, is the results can be manipulated with editing software. Is this true?
Parent - - By HgTX (***) Date 11-20-2008 15:39
The Kodak salesguy said that there's a logo on the image that goes away if the image is manipulated.  If you get it in some kind of generic graphic format, all bets are off.  If you get it in their proprietary format and view it with their proprietary viewer (if you just want to view & not manipulate, the software should be free or low cost), you should be able to tell whether the image has been messed with.

I have not seen this in action but am very interested in it and would seriously consider allowing its use.  We'd need to jimmy about with the specs a bit to allow it though; density & film type requirements would need to be replaced with something else.

Hg
Parent - - By Superflux (****) Date 11-20-2008 21:00
HG
Thanks for the onfo. I figured that technology would have come up with a "tattle tale" to make this system tamper resistant. I'm anxious to have some 1st hand experince with digital. So far, all the projects I've been around are still wrapping film.
Parent - - By raptor34 (**) Date 11-20-2008 21:05
The office I work in has been promised a digital rig so ill post some when we get it, but we were promised about 4 months ago and nothing yet so it mat be a year or so.
Parent - By Superflux (****) Date 11-20-2008 21:18
I'll be waiting at my monitor like the RCA Victor dog in front of the Victrola...
appreciate it

John
Parent - - By HgTX (***) Date 11-20-2008 21:37
The demo I saw still involved something a lot like "wrapping film", except that in place of the film, in the very same holder you used to use for film, you used this reusable screen, and then instead of developing it with chemicals, you fed it to some digital thingy to read.

Hg
Parent - - By brightblue (**) Date 11-22-2008 21:50
I have heard of this..is it also referred to as RTR ( real time radiography? ). Maybe I'm confusing two different processes here...

We do both manual ( chems ) processing and have an automatic processor at another site. The auto processor can do just about any film type you'd normally use - such as M100 or T film... though we tend to use either AGFA or Kodak AA400 with the auto processor ). But I have a computer background also and am really interested in this new method of Kodaks, so looking forward to coming back and hearing about it :). BTW, someone mentioned using 'less radiation'. Can I assume you mean using a weaker source? Does that have no impact on shot times? And the reusable screen, it goes into a cassette just like any other film? Do these screens come in a variety of sizes?
Parent - By HgTX (***) Date 11-24-2008 15:47
I guess what I've been talking about is CR.  They did have various sized screens that went into cassettes.  Although the demo I saw was Kodak (now spun off as Carestream) and they showed plenty of industrial examples, everything I can find on their website looks like it sits in a dentist's office and is not useful to show anyone here.  I'll see if I can poke my Kodak/Carestream contact to send me a link to something more interesting to the industrial crowd.

The reason for less radiation is that with conventional film, the response is not linear.  So you have to expose it for a while without getting much to happen.  Then there is a phase where a small difference in exposure gives a big difference in film appearance.  This is part of the reason for film density requirements; it keeps you in that steep response range.  With these screens, the response is linear from the beginning so you don't have to expose it as long to get the contrast you need.  So we're talking shot times rather than weaker source (though I suppose you could trade one for the other).

Hg
Parent - By HgTX (***) Date 11-24-2008 19:42
Here's the website for the stuff that I saw demoed:

http://www.carestreamhealth.com/ndt-cr-digital.html

I haven't done much poking around there yet.
Parent - - By CWI555 (*****) Date 11-23-2008 05:24
There is a difference between digital radiography, and computed radiography. DR utilizes real time sensors similar to your digital camera except the wavelength converted to image is that of the x/gamma range. Recordings are digitally stamped by the system recording it, and as mentioned, has tamper tale tells.

What you refer to "wrapping the film" is CR radiography. A specialized phospor plate is utilized in place of the film. In a general sense, the plate is first exposed, then is scanned into a reader via a laser scanner. The plate contains multiple layers, which are translated into muiltiple image layers via the differences in refraction from the various layers within the plate.

The later case is already code accepted in many cases. CR typically takes only 1/2 or less the original R factor to expose, it can reveal far more than a standard radiograph, and produces a permanent electronic record. Due to the reduced R factor, the multiple scan layers, it also makes it ideally suited to selenium, which again reduces exposure concerns and also improves the resulting shot due to the typically inherent smaller cross section of those sources.
The secondary effect on the environment and cost is also not to be forgotten. No chemicals for development. A standard office with a computer screen is sufficient for a dark room. The plates also are reusable though they do get brittle with usage.

The down side to CR radiography is initial cost. The plates are expensive, but balance out against the cost of film over time. Also, you can't use your standard screen for output.
The monitor is specialized and puts even the best HD screens to shame. With that fine resolution comes a higher cost. Trying to view a CR image on a standard screen can only be done by first setting the image on the specialized monitor, then converting it within the system software for wide spread viewing. (typically)

Over all, it is the way to go despite the cost in my opinion if your going to stay on the radiography train. I still say UT is the way to go, but for those who just can't turn loose of RT, CR is your best bet.

Regards,
Gerald
Parent - - By brightblue (**) Date 11-24-2008 01:49
Hi Gerald,
For us, it's not a case of not being willing to 'let go' of RT. It's something clients request, just like UT.

I've heard the intial cost is quite hefty. Somewhere in the 65 grand range. And the filter is around 400 bucks alone isn't it? Yes, it's reusable. But how durable is it? Can it survive the accidental 30' drop from a scissor lift? lol

Not trying to be controversial. I know that there is resistance to change sometimes. One question I've heard asked is,"Once the image is uploaded into the computer, what happens if the computer craps out?" You're stuck with no image and an unhappy client waiting around for you to deliver a result so they can get on with construction.
Parent - By Metarinka (****) Date 11-24-2008 16:44
invest in backup technology, Hard drives are very cheap, so is online storage. i would imagine this wouldn't be your standard windows box where people check their e-mail and do whatever else it is that causes virii.

Here's some more information about RTR and CT for NDT
http://www.ndt-ed.org/EducationResources/CommunityCollege/Radiography/AdvancedTechniques/realtime.htm
http://www.ndt-ed.org/EducationResources/CommunityCollege/Radiography/AdvancedTechniques/computedtomography.htm
Parent - - By Terry Vititoe 2 (*) Date 11-26-2008 14:32
We just bought a CR unit from GE at about 650K
Parent - By brightblue (**) Date 11-30-2008 03:38
Six hundred and fifty thousand dollars is quite a hefty investment. I sure am interested in it all, but think it'll be quite a while before the company I work for considers that.
Parent - By CWI555 (*****) Date 12-01-2008 15:03
Way to much for what you get from GE
Parent - - By CWI555 (*****) Date 12-01-2008 15:04
The scanning equipment is not used on the shop floor. All that is used there are the plates.
Parent - By Terry Vititoe 2 (*) Date 12-11-2008 12:20
This is the price for the Lead room, computers & training
Up Topic Welding Industry / Inspection & Qualification / Digital Radiography

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