Chapter 18 Flashcards
(43 cards)
Resolution
The ability to image fine detail
____ resolution is better
Smaller
Tinier details can be discerned
If two reflectors are not seperated sufficiently they produce
Overlapping echoes
Axial resolution aka
Longitudinal, radial, depth and range
Axial resolution is
Minimum reflector seperation along scan line to produce separate echoes
Axial resolution = ____ mm
2mm
Structures place 1 mm apart will be seen as a
Single structure
Axial resolution equation
AR= SPL/2
The smaller the AR the
Better
To improve AR we need to
Reduce SPL
Lateral resolution aka
Angular, transverse, azimuthal
Lateral resolution is
Minimum reflector seperation perpendicular to scan line to produce separate echoes
Lateral resolution occurs when _____=____
LR=Wb
Lateral resolution = width of beam
LR=3mm
Reflector seperation is less than Wb
LR=1mm
BEAM IS NARROWER THAN REFLECTOR SEPERATION
WHAT IS BETTER SMALL OR LARGE LR
Smaller
LR is improved by
Reducing the wb
Elevation resolution
Minimum reflector separation perpendicular to scan plane to produce separate echoes
Operates in 3 dimension
Elevational resolution has ____
Slice thickness aka section thickness / elevational plane
Elevational resolution can preoduce
Section thickness artifact aka partial volume artifact
Can fill in cysts or other anechoic structures
Poor elevation resolution will show
Echoes from outside the intended scan plane
Especially within anechoic structures
HOW DO WE FIX elevational resolution artifact
THI—> narrower and thinner beam
Less likely to pick up echoes from other plane
Spatial compounding
AR is less than _____mm to distinguish two seperate objects
1mm
Temporal resolution
Being able to separate echoes in time
Poor temporal resolution is visualized as lag