How to Use This Resource
Table of Contents and List of Topics
Outline
Mind Map
Learning Objectives
Online Module
Text Reference
Visuals For The Classroom
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1
The three phases of CT image formation.
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2
The x-ray tube scanning around the patient's body.
3
The image quality characteristics of a CT image.
4
A VIEW produced from one x-ray tube position.
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A CT system showing one VIEW.
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One RAY within a VIEW.
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A SCAN is made up of many VIEWS.
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A SCAN produces a DATA SET that will later be used to reconstruct an image.
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The x-ray beam is moved along the patient's body to produce images of more slices.
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The scan-and-step method produces data sets for individual slices.
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Spiral (helical) scanning moves the body continuously through the beam.
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This is what we see if we move along with the patient.
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Increasing the PITCH moves the body faster through the beam.
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CT machines can have either single or multiple rows of detectors.
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Multiple-row detectors scan faster.
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Helical/spiral scanning produces a continuous data set.
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Scan-and-step slice acquisition produces data sets for individual slices.
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Images can be reconstructed from any slice location within a volume data set.
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3D images can be reconstructed from volume data sets.
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The FILTERED BACK PROJECTION method reconstructs an image from the scan data.
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An image reconstructed from one view.
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The image is improved with two views.
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The reconstruction process divides the slice of tissue into voxels that correspond to image pixels.
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A CT NUMBER is calculated for each voxel/pixel during the reconstruction process.
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The DIGITAL-TO-ANALOG conversion is the last phase.
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Window LEVEL and WIDTH must be set to view specific tissues.
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Windowing contributes to the high contrast sensitivity of CT.
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ZOOM is the process of selecting a smaller area within the reconstructed image for display.
The End
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