Digital radiographic image processing

[@victoriabreu2498]

Hi there, I am a radiography student from Australia. I wanted to thank you for the well-made comprehensive video. It really solidified my understanding of the various concepts.

[@RockTheRegistry]

Thank you! Don't hesitate to hit me up with any questions.

[@victoriabreu2498]

To answer your question @51:34 about how DR systems know the image orientation, on Carestream Digital Receptors they have an orange edge which indicates what will be the top of your exposure. I am not sure about Fuji or other Digital Radiography systems as I have not worked with them as of yet.

[@witheredmedia]

here for the lookup table stuff, thanks!

[@derekfries4737]

Thank you for making all these videos!!!

[@shohrehpizza]

I really appreciate it. you made it easy for me to understand LUT.

[@coreyritchie1833]

I'm teaching this lesson now and today, I also mentioned the high/low kVp thing and how I didn't see it in the textbook. Based on knowledge of attenuation and transmission, I concluded that the low kVp will attenuate more of the beam, therefore causing more contrast, making it a "wider" histogram. The high kVp will cause more transmission, making it a more uniform image, giving the "narrow" histogram. Thoughts?

[@RockTheRegistry]

Great questions. I emailed the writer, and her response was she looked at the histograms generated according to JPEG images taken from the original DICOM images. My issue with that is histograms are generated based on raw data in order to process the image. Any third party histograms are only reviewing the image data. Regardless, it's a point of controversy; so they're not about to put it on the registry any time soon.

[@feelgoodquotes2515]

Is spatial resolution mainly affected by Focal spot and oid? .. saw that on one of your slides spatial frequency resolution. Could it also be affected by Sid, motion, tube angle? Just trying to understand better incase I see this on the ARRT. Thx

[@RockTheRegistry]

In digital imaging, spatial resolution is primarily influenced by pixel size. Focal spot size and OID influence spatial resolution geometrically by changing penumbra size (aka unsharpness). SID plays a role in that as well. Motion is best thought of as influencing image blur. It's an artifact. Tube angle primarily contributes to distortion.

[@aoimyul2300]

Hello, I have a question, is formation of latent image still involved in a direct digital radiography (The one with photoconductor) or nah?

[@RockTheRegistry]

Great question! Not so much. I mean there's something stored in the TFT but it's like for a fraction of a second. So I'm going with no latent image for direct digital.

[@souayang89]

What text book do your school use?

[@RockTheRegistry]

Digital Radiography and PACS by Carter and Veale

[@candiceward7117]

At 13 minutes, the conversation turns to high kVp creating a narrower histogram than low kVp. Is this because the Grey tones created at higher kVp levels are represented in the middle of the histogram, whereas the black and white (high contrast) created at low kVp levels are represented at the extreme left and right sides, thereby creating a wider graphed area for low kVp? The explanation might actually be too simple.

[@RockTheRegistry]

Great question! I'm simply repeating what's in the textbook, but I believe this a point of controversy. I wrote to the authors of the textbook with this same question. They answered that they used a third party software to analyze images and produce histograms... the high kVp images produced narrower histogram. In my understanding, this process introduces more extraneous variables. Long story short there's enough controversy around this concept that I don't anticipate it will be on the registry. I also don't see it being terribly necessary to clinical practice. Long story short - I need more information before I can say whether your rational is correct or incorrect ;)

[@limamaria100]

@@RockTheRegistry I think it may be because as the kVp increases the signal strengths received are fairly similar to each other (less distinct steps in the gray scale) therefore being able to display more anatomical features in a smaller data range creating a narrower histogram. The opposite of what we are programmed to think with high kVp and long scale of contrast. Just a guess...??

[@RockTheRegistry]

@@limamaria100 I like this guess, but to me a narrower histogram equals increased contrast, which simply doesn't jive with increased kVp. Increased kVp should result in decreased contrast. The truth is out there!

[@limamaria100]

We will find it! Thank you for your amazing and helpful lectures!

[@RockTheRegistry]

@@limamaria100 You bet! Keep the questions coming. Also, you might enjoy the medical thriller Time, Distance, and Shielding. It's about an x-ray tech taking on an evil surgeon, and there's tons of stuff about patient care and radiation safety - www.amazon.com/dp/B088867YHK