Flashcards in Ch.2 Ct Image Formation Deck (83)
Digital images are?
Numerical representations of an object that can be recognized and processed by a computer
First step generating digital image of an object?
Divide the object into a grid of small regions
Picture element that's each small region of a grid
Rows and columns allows us to ?
Associate the location of specific structure within the object being imaged with specific pixel or group of pixels
Grid of pixels
2nd step generating image
Sample the object in order to differentiate structures within the object and assign various shades of gray to the pixels representing the structure
X-ray photons that pass thru the body are measure by ______and converted into ______?
Posit e or negative whole numbe
Value of integer determined by?
Assigns specific gray level to region of Ct image from which attenuation information was detected
View of anatomical cross section from particular vantage point
Ct scanning methods
Obtained with stationary X-ray tube and patient table in motion
Why localizer scan ?
Aligns cross sectional slices with specific anatomical structures
Views used with localizer?
Length of anatomical coverage with localizer depends on?
Speed of table
Amount time X-ray is on
Ct localizer scan the anatomical structure appears? P 10
Ap localizer image used? P 10
Planning to specify perfectly transverse slices
Lateral localizer is used? P 10
Intend to angle gantry to specific oblique slices
Which ct yields the best quality image free of helical artifacts?
Conventional ct used today?
Neurological studies involving temporal bones
Cardiac calcium scoring
Conventional ct the tube rotates around the patient while the table?
Data measured at each projection placed in computer file
Single row detector
When performing a conventional scan , raw data from ____ cross sectional slice location is collected during a single rotation of the gantry?
Multi row detectors
When performing a conventional scan of multi row detector scanner , the raw data is from ______ cross sectional slice locations collected during a single rotation of the gantry
Raw data sample formula
Rows of detectors x # of detectors X projections required
X-rays beam spiral or corkscrew paths around patients body as the table advances through the gantry