Scanner ? 256 rows of detectors
8 centimeters of coverage, with the entire heart covered in two scans The rotation speed is 0.27 seconds (total .54 seconds with 120 kw of power.
Now available 640 rows and in .27 secs we scan the whole heart in one rotation
Ashley Davidoff thecommonvein.net
Gave numbers to the pixels
(just like the the 0 and 1 of computer science)
Enabled Objectivity ? Ability to Accurately Measure
Applying the Segmental Approach to Complex Structures
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The Power of the Brick
It is Nothing by Itself However the Whole is Only as Strong as the Weakest Brick
By Ashley Davidoff MD TCV-0039 TheCommonVein.net
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When the 37.2 trillion cells in the human body connect and organize, they create a spark of life housed in the body and gifted with a mind. By Ashley Davidoff MD
TCV-0040 TheCommonVein.net
So for example looking at these liver cells
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Cell Size 10 to 100 µm
And most of the time in clinical practice we use subjectivity
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Subjective Evaluation of Character
Ashley Davidoff MD
thecommonvein.net
#subjectivity#Davidoff art #principles#character #diagnosis
character-0003
and on that basis we give the structure under evaluation
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In the world of digital technology the cell = the pixel/voxel = about 1mm
The pixel has a number embedded within it
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Digital Information
Once we have data in pixel form we can manipulate the data and this is the strength of digital acquisition
Ashley Davidoff MD
thecommonvein.net
This methodology is therefore able to provide objectivity, enabled by better measurement provided by better tools (computer algorithms)
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Subjectivity vs Objectivity in Science and Medicine
Ashley Davidoff MD
thecommonvein.net
Familiar to all is the Hounsfield Number relating to the density
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Density of Body Tissues Based on Hounsfield Units . The human observer can perceive around 900 shades of gray.
Ashley Davidoff MD thecommonvein.net
Blooming Artifact
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Blooming Artifact
The small calcified plaque in the top left image is an artistic version of the reality ? calcified plaque that does not impinge on the lumen. The top right image is a CT in the ideal world recreated within the grid of pixels (voxels in 3D) The calcified plaque (white arrow) which shares a voxel space with the blood in the lumen) remains distinct and true to its size, demonstrating true lack of impingement on the lumen
The bottom row in gray scale shows what happens in a CT scan. The bottom left image shows what the CT would look like ie impingement by the plaque on the lumen. The bottom right explains the blooming artifact. The calcium of very high density (about 500HU) shares the voxel space with the blood which is soft tissue density (about 50 HU) and so the net density is about 450 HU. The voxel does not therefore reflect a true density and the lesion therefore appears to impinge on the lumen when, in actuality it does not. This is called the blooming artifact
Ashley Davidoff MD thecommonvein.net
