We’ve been told by GE that they are working on the stitching function and that it is coming “soon,” but we haven’t been given any firm date on when that is gonna happen.

We have exported the DICOM files as a TIFF and then used Photoshop to stitch them together. This can get a bit unwieldy, though, if you don’t watch your file size. Can you imagine stitching together 10 20mb images? Yikes.

The other issue we haven’t fully resolved is the archiving process, but this could likely be somewhat easily resolved if we were to put in the necessary time to figure it all out. I know we made some major headway on this recently, but I haven’t had a chance to get back to the software and really see what it can do.

Thanks for the comment!

Richard

I’m sorry to have taken so long to respond. Thanks for your comment and kind words.

I think it’s hard to say what film the Phosphor Imaging Plates compare to. Here’s a link to some info about the plates:
http://204.168.119.39/download/products/xr/cr_dr/GEIT-200044US_phosphor-plates.pdf

I’ve been working with the system now for a long enough to know that it takes a little while to learn how to take a very good image. It’s kind of a new way of thinking; maybe it’s just me, but I haven’t tried to think of correlations between the film and phosphor, I just try and make it work on the phosphor.

I hope that makes sense.

Regards,
Richard

Angeliki

I hope this answers your question, Angeliki.

I asked Mark Mc from GE to respond to this comment because I thought they would be better positioned to provide an answer.

I can only tell you anecdotal information as we’ve only had the system for about a year.

The one thing I’ve noticed with the plates is that you have to take care not to leave dust on them or on the scanner itself (the plates move across it during the scanning process). I have seen very thin lines in the image when I haven’t taken the time to dust the scanner before I scan.

Richard

“Do you know which is the lifetime of an imaging plate?
I am worried that it could be overstimated.”

The physical plate will wear out before the chemistry of the plate stops holding x-ray images. If proper care is taken with the CR plates, you can expect many thousand exposures on them. Typically, scratches, dirt, and rough handling will bring about the end of a CR plate’s life.

In regards to “dead pixels”, this really is not an issue with CR imaging technology. The CR plates emit light when stimulated by the scanner’s laser. This light is integrated to a digital signal by the scanners photomultiplier tube. There are no pixels on the plate, as is one continous surface. This is in contrast to flat panel imaging detectors, which have a finite number of elements which collect the x-ray energy (we will call them “pixels”). If a pixel on a flat panel is bad, it can typically be calibrated out by taking the values of surrounding good pixels.

Moreover I would like to know of how you deal with the problem of dead pixels. What is the limit of screen-pixel drop-off? Which are the equivalements of requirements of film type and denisty. I mean that in film radiography we have classes of films is there any similar standard with classes of pixels?

Kind regards

Thanks for “stealing” those links! The more people who know about this good stuff, the better. And apologies for taking your thread off-track, since computed radiography is ripe for an active and focused discussion of its own. But to briefly answer your question:

> I wonder, though, if there is interest in making these
> radiographic images available to the public, once digitized.

Yes, in fact that is one of the long-term goals that is under discussion for x-ray archives (the final bullet point on the agenda).

ARTstor is one possible venue that could provide access to these federated collections, given its teaching and research mission. The side-by-side viewing tools available through the site would allow for pairing visible light images (where available) and x-rays for comparative study across numerous institutions.

Of course, whether scanned or born-digital, individual institutions are free to present their content however they choose. Similar side-by-side views could certainly be achieved in local online collection databases. It is more often an issue of resources and priorities than stated interest.

The x-ray archive agenda is one part of the Mellon Foundation’s broader initiative exploring the challenges, complexities, and opportunities of Conservation Documentation in Digital Form. The topic of public access continues to figure prominently in all of these discussions (transcripts, documents, publications, etc. all on http://mac.mellon.org).