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Computed Tomography

QuestionAnswer
What is the Computed tomography A process of creating a cross-sectional image of any part of the body
How does it work x-ray tube rotates around the patient's body and a detector assembly measures the radiation exiting the patient.
Who is the father of CT Godfrey Hounsfield
Who was Hounsfield partner Allan Cormack
When and where was the first scanner demonstrated? 1970--England
Who invented the whole body CT scanner Robert Ledley
Pencil thin x-ray beam, One detector, 4.5 minute exposure time for one slice and head imaging only 1st generation CT scanner
Translate/rotate movement, fan shaped x-ray beam, 30 detectors(array), 15-20 sec/slice, improvement in image quality 2nd generation CT scanner
Rotation/rotate, 750-960 detectors, curved detector array, 1-10 seconds/slice 3rd generation CT scanner
fixed ring of 4800 or more detectors, increaded patient dose per scan 4th generation CT scanner
Gantry rotates continuously while the table or couch moves through the gantry aperture at the same time Spiral/Helical Scanning
Allows for the continuous rotation of the xray and eliminates the need for a cable between the gantry and the generator Slip ring technology
Detector arrays with multiple rows of elements along the z axis. Multi-slice Spiral/Helical CT
Covers the entire body sections in a single breath hold and it used for cardiac imaging Volume CT (VCT)
Name the CT system components Gantry, computer and operator console
Name the Parts of the Gantry x-ray tube, slip ring, detector array(solid-state), collimators (prepatient/postpatient)
What is the opening of the Gantry called Aperture
Moves in increments according to the scanning parameters; made of wood or low density carbon composite; max weight limit 300-600lbs Table/Couch
What are the four basic functions of the computer system Data Acquisition, Image reconstruction, Image data storage and Image display
What is more accurate high pitch or low pitch setting and why low pitch is most accurate, the helical loops are shorter.
The range of CT numbers that are used to map signals into shades of gray is referred to as Window width
What determins the midpoint of the range of gray levels to be displayed Window Level
The initial image taken in a CT scan is termed localizer, scout or scanogram
incrementation of patient table; start/stop tube/detector rotation is called Conventional or Serial
Continuous patient table movement and tube/detector rotation is called Helical or Spiral
What are the advantages of CT over conventional radiography Eliminates superimposition; able to differentiate among tissues with similar densities .5% difference
the amount of data displayed on the monitor depends on what FOV
Can the Display FOV be greater than the Scan FOV No
What is used to reconstruct images using reconstruction algorithms Digital Values
When volume is added to a 2D pixel, what is produced Voxel
The number each pixel withing the matrix is assigned is called the CT number or Hounsfield unit
What is the CT number or Hounsfield number for water zero
Name three diagnostic applications for CT Scanning Head Trauma, Chest/abdomen/pelvis, Interventional procedures
What is the purpose for contrast media in CT to distinguish normal anatome from pathology and to make various disease processes more visible
In what ways can contrast be administered Intravenously, orally, and rectally
What is the percent is the oral Barium sulfate mixture 2%
The amount of blurring in an image is referred to as Spatial Resolution
The ability to differentiate between small differences in denstiy is called Contrast Resolution
What arises from the random variation in photon detection Noise(Quantum noise) Affects contrast resolution and makes image appear grainy or mottled
Created by: aldo.banos
 

 



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