Ch. 29 Computed Tomography
Advanced Procedure
Fundamentals of CT - correct answer ✔✔CT= the process of creating a cross-sectional tomographic
plane of any part of the body
-Tube rotating around the body part
-Exit radiation measured by detector assembly which send this information to the computer
Fundamentals of CT - correct answer ✔✔Computer uses algorithm to compile & calculate data
Computer assembles data into matrix to form axial image
Each image, or slice, displayed on cathode ray tube-CRT- in cross-sectional format
CT & Radiography - correct answer ✔✔CT has improved contrast to demonstrate similar density.
CT eliminates superimposition encountered in xray by passing a collimated beam through a part at many
different angles
CT has image manipulation & enhancement techniques
Historical Development of CT - correct answer ✔✔1970- England= first successful demonstration by
Godfrey Hounsfield & Allan Cormack
1973-United States= Mayo Clinic installed
*First units were dedicated head scanners
, First Generations of CT - correct answer ✔✔1st = pencil beam & 3 detectors
2nd = fan beam & 30 detectors
* 1st & 2nd tube rotates, then returns to starting position= translation/rotation
3rd = both tube & detectors rotate around patient
4th = tube, but not detectors rotate around patient
Technical Aspects - correct answer ✔✔-CT provides information on positional relationships & tissues
characteristics.
-Detectors measure exit radiation, convert it to an electronic signal & send it to a computer
*Raw data= measured xrays transmission values
Technical Aspects - correct answer ✔✔Value of each number is directly proportional to signal strength
Digital image displayed in matrix
Matrix = a grid of rows & columns
Pixel = single square, pr picture element, within matrix
Slice thickness adds volume dimension
Technical Aspects - correct answer ✔✔Voxel = volume element of matrix; product of pixel area & slice
thickness
Advanced Procedure
Fundamentals of CT - correct answer ✔✔CT= the process of creating a cross-sectional tomographic
plane of any part of the body
-Tube rotating around the body part
-Exit radiation measured by detector assembly which send this information to the computer
Fundamentals of CT - correct answer ✔✔Computer uses algorithm to compile & calculate data
Computer assembles data into matrix to form axial image
Each image, or slice, displayed on cathode ray tube-CRT- in cross-sectional format
CT & Radiography - correct answer ✔✔CT has improved contrast to demonstrate similar density.
CT eliminates superimposition encountered in xray by passing a collimated beam through a part at many
different angles
CT has image manipulation & enhancement techniques
Historical Development of CT - correct answer ✔✔1970- England= first successful demonstration by
Godfrey Hounsfield & Allan Cormack
1973-United States= Mayo Clinic installed
*First units were dedicated head scanners
, First Generations of CT - correct answer ✔✔1st = pencil beam & 3 detectors
2nd = fan beam & 30 detectors
* 1st & 2nd tube rotates, then returns to starting position= translation/rotation
3rd = both tube & detectors rotate around patient
4th = tube, but not detectors rotate around patient
Technical Aspects - correct answer ✔✔-CT provides information on positional relationships & tissues
characteristics.
-Detectors measure exit radiation, convert it to an electronic signal & send it to a computer
*Raw data= measured xrays transmission values
Technical Aspects - correct answer ✔✔Value of each number is directly proportional to signal strength
Digital image displayed in matrix
Matrix = a grid of rows & columns
Pixel = single square, pr picture element, within matrix
Slice thickness adds volume dimension
Technical Aspects - correct answer ✔✔Voxel = volume element of matrix; product of pixel area & slice
thickness
