Computed tomography Flashcards
What is CT ?
Produces transverse or axial images of the body by synchronizing the x-ray tube and detectors
Advantages over diagnostic imaging ?
Overcomes superimposition of anatomy
More sensitive to small differences in tissue composition
Difference between CT and CT thin ?
Is type of cross sectional imaging in which all unwanted planes or layers of a body are completely eliminated
CT thin beam is transmitted through a specific cross-section, striking special detectors opposite the x-ray tube
Fundamentals of CT ?
An X-ray tube rotates around the body
A computer compiles the attenuation data
Digital image displayed as a slice ( image display)
No conventional image receptor
What measures the radiation after it has passed through the body ?
Detector assembly
What is used to reconstruct an image from the data stored on the computer ?
algorithm
CT components ?
Gantry
Computer
Operator Console
The Gantry ?
1) X-ray tube, detector array, collimators, mechanics that provide motion
2) Angled 30 degrees in 2 directions
3) Table ( couch) linked to gantry
What are 2 types of collimator ?
which reduces patient dose
Pre patient : At x ray tube restricts beam exiting CT tube
Post patient : at detector which shape and limit beam
CT images ?
Differentiates between tissues with similar densities
Reduces scatter in the image
Has very high image contrast resolution
What is the goal of CT ?
Minimal superimposition
Improve image contrast
Recording of very small differences in tissue contrast
Advantages of CT ?
3D imaging
multi-plane image reformatting
Excellent contrast resolution is possible because of high collimation and special detectors
What is difficult to image in CT ?
Surrounding by large amounts of bone such as
posterior fossa , intrapetrous space and
spinal cord
what are rare benign tumors ?
Chondromyxoid fibromas
