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Latest 2025/2026.
The word Tomo is tomography means
To cut
What is the Z-axis
the thickness of a cross-sectional slice.
The degree to which an x-ray beam is reduced by an object is referred to as
Attenuation
The amount of the x-ray beam that is absorbed per unit thickness of the absorber
Linear Attenuation
difference in linear attenuation coefficient is responsible for
Image Contrast
These are the two dimensional squares of the matrix
Pixels
The 3d dimension of the matrix are known as
Voxels
Number of pixels in a matrix are product of number of
Rows and columns
Beam attenuation of CT are measured in
Hounsfield Units
Scan Data is the same as
Raw Data
The ability of a system to define small objects distictly
Spatial Resolution
This image quality's criteria refers to the speed at which the data can be acquired
Temporal Resolution
This image quality criteria is the ability to differentiate objects with similar densities
Contrast Resolution
Multi slice is defined as _ to _ slices per gantry
,4 to 320
the time required to acquire all x-ray projections that are needed to reconstruct one CT image
Temporal resolution
2 advantages of volume scanning are
shorter scan times
scanning more volume of anatomy
A single image reconstructed from a volume of acquired data.
Slice
he group of slices which make up a particular examination
Scan
Refers to a single exposure which results in an image much like a conventional x-ray
Localizing Scan
determines how many detector cells collect data
Scan field
determines what portion of the scan field of view is reconstructed
field of view
This centre point is called
display field of view centre
defined as the x and y distance from isocentre in cm
display field of view centre
These mathematical algorithms help generate 2-D axial images from the spiral (3-D volumetric) data
interpolation algorithm
If the image has fewer shades of grey, it presents with increased image contrast (more black and
white) and is expressed with a
narrow window width
more shades of grey are expressed with
wide window width
Ct provides us wih
cross-sectional images of the body
CT numbers are also known as
Hounsfield units
2 advantages of CT over X-ray
, Elimination of SI of structures
Improvement of contrast resolution
Ring-shaped part of CT scanner. Many of the components necessary to produce and detect x-rays
are housed within
Gantry
electromechanical devices called___ to provide continuous electrical power and electronic
communication across a rotating surface
Slip Rings
Collect attenuation x-ray beam information.
Detector Array
2 Types of filters in CT
Shaped and Bowtie
The process of moving the table by a specified measure is most commonly called
Incrementation
Cell Detectors should be __ to improve spatial resolution
Small
Greater quantum efficiency of detectors equals better
Contrast resolution
The greatest innovation in CT since the advent of CT itself
high speed or slip ring scanners
For multi-slice scanner Slice acquisition rate=
slices acquired per rotation/rotation Time
a number of computers are used to run various functions of the scanner simultaneously
Parallel computing
Slip ring technology allowed us to have
Continuos Acquisition
Dual source scanning mean
2 xray tubes
Scanning where 2 different KVs are used
dual energy scanning (shows differences in tissue characteristics)
A filter which can enhance or suppress tissue
Reconstruction filter