How It's Made: A Video Introduction to Computed Tomography
November 02, 2016
Computed tomography (CT) goes light years beyond regular 2-D X-ray technology to deliver accurate three-dimensional images ...
Computed tomography (CT) goes light years beyond regular 2-D X-ray technology to deliver accurate three-dimensional images of scanned objects, including their voids and areas of differing density. Jason Robbins, YXLON Senior Product Manager, explains the science of CT in this (fun and nerdy!) educational video.
About the Video Tutorial
This talk includes a detailed discussion of how to correct for various types of image artifacts as well as a comparison of the primary scanning techniques: cone beam CT, fan beam CT, helical CT, and laminography. Sample images are taken from specific X-ray inspection applications in aerospace, cast parts, and electronics industries.
Using X-ray technology, researchers, manufacturers, and designers from any industry can learn the most amazing things about the products, parts and samples they care about. Watch this 46-minute video to get a start on your "X-ray PhD." You'll learn about:
- The history of X-ray technology and what distinguishes it from medical X-ray.
- System components and what features are important for different applications.
- Image acquisition and how images are reconstructed for analysis.
- How specific calculations are derived: voxels, field of view, total scanning time, etc.
- How to identify and mitigate artifacts in images.
- Modes, corrections, and features to obtain the best image for various applications.
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Origins of Computed Tomography
"The phrase itself comes from the Greek word "tomos" meaning slice, and "graphein" meaning to write. This is something you have to put in every presentation about CT because you have to start somewhere. So, we'll start back with the Greeks. CT is not as old as ancient Greek culture. To make a CT scan, we have a two-dimensional density map of a cross section of an object and we put it together. We have a large number of projections or views (you'll hear us say this term), at many different angles. Then you put them all together in a computer and you get a 3D image. But it's important to know that CT was originally dedicated to inspections of human heads, and that's why many people think about CAT scans or they think about the slice of the brain. That's how it got started."
Generations of CT
"Generations of CT technology were created. The first generation started with one detector with one beam that was translated and rotated around. Then, in the second generation, there was an array of detectors. Again, these were mostly medical at the time. Then in another advancement, they added a fan-beam for the X-ray source which was then translated for rotation. This means you move the source and you connect it to software that tracks the movement. Then you have a third generation, where it's a fan-beam, and you only rotate. You see these in a lot of these medical scanners. This is what we mainly do at YXLON. In the third generation of machines, where you have a single source and you have an object that rotates, there are different types of detector elements. There are line detectors or area detectors, depending on the application, and we only move the object. We do have modes where we move other things. The big difference between industrial and medical, of course, is that we rotate the "patient" while in medical applications, they rotate the source of detectors, such as a big round ring around a gurney. There's some cool YouTube videos of this that show these gantry things rotating at the maximum speeds. It's amazing how fast these things are going! In industrial X-ray for non-destructive testing, our "patient" doesn't move around as much, and we're not nearly as dose-sensitive. So, we have the advantage to take longer scans and things like that, where if they did that in a hospital, it would be sort of the opposite of what they're trying to achieve."
Watch the video to learn more.
If you have any questions about how non-destructive computed tomography could be applied in your manufacturing or research operation, please contact Dirk Steiner at email@example.com or 770-289-7708.
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