Definitions
The ability to distinguish two structures lying close together (side-by-side) is called…
lateral resolution
Longitudinal is another name for…
Axial resolution
What is the unit of measurement for axial resolution?
mm
Three methods of focusing are???
External focusing
Internal focusing
Phased array focusing
Lateral resolution is determined by?
Width of the sound beam
Which frequency level (high or low) improves both axial and lateral resolution?
high frequency
The mnemonic LARRD stands for…
Longitudinal, Axial, Range, Radial, Depth
What is the relationship between lateral resolution and beam diameter?
Directly related
Lower numerical values of axial resolution indicate a (longer/shorter?) pulse.
shorter pulse
Axial resolution is determined by?
Spatial pulse length and pulse duration
Axial resolution measures the ability of a system to display what?
Two structures that are close together when structures are parallel to the main axis
The mnemonic LATA stands for…
Lateral, Angular, Transverse, Azimuthal
What is the formula of axial resolution in soft tissue?
Axial Resolution (mm) = 0.77 x #cycles in pulse/frequency (MHZ)
If the transducer diameter is 9 mm what is the lateral resolution at the depth of 8 cm?
4.5mm
Which type of resolution is better in clinical imaging systems?
Axial resolution, because ultrasound pulses are shorter than they are wide
Define external, internal, and phased array focusing:
External focusing: a lens is placed in front of the piezoelectric material
Internal focusing: a curved piezoelectric crystal concentrates the sound energy into a narrower or tighter beam
Phased array focusing: the electronics of the US system focuses the sound beam
What is another name for fixed focusing?
Conventional or mechanical focusing
What is one of the equations to find axial resolution?
Axial resolution (mm) = spatial pulse length (mm)/2 OR
Axial resolution (mm) = wavelength (mm) x #cycles in pulse/2
True or false: When two side by side reflectors are closer to each other the width of the beam only one reflection is observed on the image.
true
What are the two ways a short pulse is created?
Less ringing and higher frequency