CT Pitch and Field of View
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- Опубликовано: 27 июл 2024
- 0:03 Helical Pitch
1:17 Low Pitch
1:35 High Pitch
2:00 Low Pitch (Oversampling)
2:41 High Pitch (Undersampling)
3:40 Field of View
3:49 Scan Field of View (SFOV)
4:29 Display Field of View (DFOV)
5:33 Field of View Summary
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As a radiologist in the making this helped me tonnes! Thankyou so much!!!
Thanks for the explanations, keep up the good work. One clarification is that at pitch greater than 1 there is typically not a gap and the data is not undersampled. There is less than a full scan of data but reconstruction can still be very accurate in this scenario. I know some books show this as a gap but this is a misnomer. Above pitch 1.37 or so is where data starts to be missing depending on DFOV.
Clear and great explanation. Thank´s for your job !
Thank you very much. Very informative.
Very useful! Thanks a lot! Clearly explained!
Thank you, great video 👍🏻👍🏻👍🏻
omg this saved me THANK YOU!!
Great explaination ❤❤❤👍 ,it is easy to understand 😉
Thank You So Much
Very useful
Thank You So Much
Dear Sir thanks for such easy and instructive concepts. Can you please make a video on type of detectors. i.e (SSCT, MSCT, True Volume Isotropic, Istropic , Anisotropic (Adaptive). Thanks looking forward
Best wishes
Thanks for your comment and video suggestion. I talk about detectors in some of my other videos but not in as much depth as you are requesting. A quick summary with regards to the types you have described:
SSCT = Single Slice CT, acquiring one slice at a time. This is the original design of older CT scanners, where one rotation corresponds to one slice.
MDCT = Multidetector CT, basically meaning multiple slices are acquired in each rotation because there are multiple rows of detector elements. Some modern scanners have 64, 128, 256 or more rows of detectors, meaning they are able to acquire a lot of data in a short amount of time. This is described a bit in my first video on this channel (CT Basics: Major Components).
Isotropic detectors: The principle of isotropy means voxels are equal in size in all dimensions (i.e. voxels are a cube, not a cuboid).
Anisotropic detectors on the other hand would give voxels that are longer in the Z-dimension than in the X and Y dimension, so even though you have a square pixel on an axial image, the volume represented by that pixel is a thicker slice.
Adaptive detector arrays are detectors which have multiple different options for slice thickness. Generally they will have a section in the middle with smaller detector elements (e.g. 8 x 0.5mm) and then extra larger elements at the periphery (e.g. 8 x 1mm slices). In this example you would end up with 4 x 1mm slices at one side, then 8 x 0.5mm slices in the middle, then 4 x 1mm slices at the other side. You can choose to use either the whole detector, or only the higher-definition central portion, depending on the application (e.g. for fast acquisitions like most body scans, you would use the whole detector as 1mm elements, and for high def acquisitions like temporal bones you would use only the central 0.5mm elements).
Most modern scanners use isotropic detectors.
Overall it's too much to type but thank you for the suggestion, I will consider this for another video.
Thank you for your video, i wonder if you can eaplain the principle of spiral CT reconstruction, that will help me a lot, much appreciated.
Thats just not true in 80 and more % of the cades that increasing the pitch is decreasing the dose ore the other way. Show me a scaner where this is the case in dose modulated scans (there is no one). Thats only true with scaners during not dose modulated scans with GE and Canon. Because there are working with ma and not mas like siemens or Philips.