CBCT- The Basics I Flashcards
what are the digital image processing/modifications
- compression
- imaging manipulations
- image reconstruction
what are the imaging manipulations
- automated image analysis
- qualitative- changes pixel’s digital value
- quantitative - counts the number of pixels
what is image reconstruction
data is utilized by other software programs and produces different image presentations
what is computed tomography
use of computers to generate multiple images of an object from digitized density information obtained from various signals; x- radiation (MDCT, CBCT), magnetic fields (MRI), sonar radiation (ultrasound)
what does CT stand for
computed tomography
what are the two forms of x ray CT
CBCT and MDCT
what does CBCT stand for
cone beam computed tomography
what does MDCT stand for
multi detector computed tomography
what is the difference between MDCT and CBCT
MDCT images hard and soft tissue, more powerful and sophisticated than CBCT. CBCT can only image hard tissues
when and where was CBCT developed
in Japan and Europe in 2000
what was the first CBCT available in the US
Newtom 2001
what is the benefit of stand up CBCT
get patient in and out faster
what CBCT do we have at school
i-CAT FLX
what are the models for i-CAT
V8,V10 or V17 models
most sit down units have ___ detector
larger
the faster the scan, ____ information and ____ image quality, and ___ dose
less; lesser; less
the longer the scan, the _____ movement artifact
more likely
what are the carestream CBCT units
CS 8100 and CS 9300
CBCT technology becomes outdated due to competition from
competitor brands
- technical innovations: memory, bit depth, FOV options, operating systems, compatibility with software technologies
what is the lifetime of a CBCT unit
6-8 years
what are the benefits of cone beam imaging and why
less radiation than other forms of CT for hard tissue imaging because of less scanning of x-radiation and lower radiation
why is there overlap in dose between CBCT small, medium and large FOV
there are other factors that affect the dose in CBCT
what are the factors affecting CBCT dose
- FOV
- exposure
- voxel
- sensors
what is FOV
field of view
- how big of area we are scanning
what does the CBCT FOV flat panel detector look like
- cylindrical shape and measurement characteristics
- diameter (mm) x height (mm)
describe the CBCT FOV image intensifier detector
- round spherical shape and measurement characteristics
- diameter (mm) only
- if it gives you radius or diameter you know its image intensifier detector
different sizes of FOV image:
different parts of head and neck
larger detector, ____ expensive
more
what is the range of kV in CBCT
75 kV- 120 kV
what is the range of mA in CBCT
7 mA - 20 mA
what forms the projection data
multiple basis image projections
what is a volumetric data set constructed by
an imaging software program which then displays various image reconstructions
X- ray beam projection scheme shows “cone” beam imaging geometry with the resultant production of:
a basis image
describe the CBCT basis image capture
- rotates and keeps taking photos can take up to 600 images or as little as 100
- you’re taking skull images at different angles
- these are digitized and stored in computer then are sent to software which can reconstruct images
- rotates counterclockwise
the more projections you take:
the better you can construct what the actual object looks like
higher resolution = ____ dose
higher
what factors affect number of basis images
- image quality
- dose
the more images you take the ____ dose, the ____ image quality
more; better
each image we take in a CBCT is called:
a basis image
what is a voxel
a pixel in CBCT because it is a 3D shape
what affects voxel size
resolution
the ____ the voxel, the better the resolution
smaller
smaller voxel size, you need ____ dose to capture everything because:
more; more photons have to hit each voxel
small voxel yields ____ signal to noise ratio, i.e _______
lower; degraded image quality
smaller voxel what scatter do you pick up
compton
what are the types of CBCT image detectors
- charge-coupled image intensifier detector
- flat panel detector
distortion of the image grid in image intensifier detector when:
moving away from the center
what is the distortion pattern of the flat panel detector
- image receptor area receiving the signal from the flat panel detector’s scintillator is flat.
- even at more distant areas from the center of the grid, there is minimal to no distortion of the grid pattern
