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20 Cards in this Set
- Front
- Back
A ________________ is applied to the raw data during image reconstruction. This process is called ________________.
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reconstruction filter
convolution |
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What are the two reconstruction filters and what does each do?
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2 types: sharp & smooth
sharp - improves edges smooth - minimizes grainy appearance or noise |
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True or False - With 1500 projections, the back projection reconstruction would closely resemble the original object.
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False, back projection(on its own) can never provide enough data to closely resemble the original object
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Sharp reconstruction filters are often used for visualizing ________________. Smooth reconstruction filters are often used for visualizing ________________.
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musculoskeletal detail
soft tissue contrast |
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Sharp recon filters are also beneficial for ________________.
Smooth recon filters are also beneficial for ________________. |
high contrast regions
low contrast regions |
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If back projection was applied to the raw data without convolution, the tissues in the resulting image would have ________________ and would be ________________.
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blurry edges
grainy or noisy |
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What is cone beam artifact?
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When a CT tube's cone beam and the structures at the periphery of the image are not properly reconstructed with filtered back projection. Has a "spoke" or "star-like" appearance.
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To prevent cone beam artifact when using a cone beam, ________________ must be used during final CT image reconstruction.
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cone beam reconstruction
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________________ requires the raw data, which is lost once that portion of the raw data storage device is overwritten.
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retrospective reconstruction
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The raw data of scan is retained on the ________________.
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raw data storage device on the host computer
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On ________________ scanners, a retrospective reconstruction is commonly used to modify the reconstructed slice thickness.
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MDCT
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________________ allows for the reconstruction of images in planes that would otherwise be difficult or impossible to acquire with CT.
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multi-planar reconstruction
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Multi-planar reconstruction requires ________________. The ________________ is not utilized.
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image data
raw data |
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Slices with no gaps in them are called ________________.
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contiguous
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Using ________________ in the initial data set improves the quality of the reconstructed images.
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overlapped slices
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What does 3D SSD stand for?
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3D Shaded Surface display
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In 3D SSD, you can set the threshold value equal to the ________________ of the tissue on which we want the surface rendering, so tissues with other ________________ are ignored.
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CT number
CT numbers |
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3D SSD is better at extracting ________________ than at distinguishing fat, muscles, and other soft tissues.
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bony surfaces and skin surfaces
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Volume rendering can incorporate information from the entire image data set, rather than just a surface, into the post-processed images, enabling visualization of ________________.
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structures above and below the surface
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VR uses ________________ or pixel volume for its display.
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voxels
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