book study questions Test4 Flashcards
What is the ability to accurately distinguish two structures lying close together called?
resolution
the ability to distinguish two structures lying close together front-to-back or parallel to the sound beam is called?
longitudinal, axial, range, radial, or depth resolution
axial resolution is measured with units of:
distance (ex. mm)
if there are more cycles in a pulse, the numerical value of range resolution is (greater, lesser, same)
greater
if a new pulsed transducer has many more cycles in its pulse, the image accuracy (improves, degrades, remains the same)
degrades
(high, low) frequency transducers generally have the best range resolution
high
which of the followin transducers has the poorest axial resolution?
a. 1.7MHZ and 4 cycles/pulse
b. 2.6MHz and 3 cycles/pulse
c. 1.7MHz and 5 cycles/pulse
d. 2.6MHz and 2 cycles/pulse
c
this is the longest pulse
it has the lowest frequency and the most ringing
(more cycles/pulse)
in soft tissue, a 3 cycle, 1MHz pulse has a pulse length equal to 4.5mm
what is the axial resolution?
a. 3mm
b. 1mm
c. 2.25mm
d. 1.54mm
c
in this setting, the axial resolution is 2.25mm
axial resolution is 1/2 of the spatial pulse length
(4.5mm/2=2.25mm)
which of the following transducers has the best axial resolution?
a. 1.7MHz and 4 cycles/pulse
b. 2.6MHz and 3 cycles/pulse
c. 1.7MHz and 5 cycles/pulse
d. 2.6MHz and 2 cycles/pulse
d
this is the shortest pulse
it has the highest frequency and the least ringing
(fewest cycles/pulse)
two different transducers create sound pulses
one transducer is labeled 5MHz and the other, 3MHz
which transducer is more likely to create a more accurate image with respect to axial resolution?
which transducer probably has a lower numerical value of axial resolution?
5MHz transducer is more likely to create an image with better axial resolution
the higher frequency transducer creates a shorter pulse and thus has a lower numerical value of axial resolution
lower numbers mean improved image quality
two different transducers create pulses
both transducers create sound with a frequency of 4MHz
one transducer creates a pulse that comprises 6 cycles and the other, 3 cycles
which transducer is more likely to create a more accurate image with respect to axial resolution?
whcih transducer has a lower numerical value of axial resolution?
3-cycle pulse transducer is more likely to create an image with better axial resolution
less ringing, or fewer cycles in a pulse, generally implies shorter pulses and improved axial resolution
the 3-cycle
pulse has a lower numerical value of axial resolution
lower numbers mean improves image accuracy
two differnet transducers create pulses
one transducer is labeled 5MHz and the other is 3MHz
the 3MHz creates a more accurate image with respect to axial resolution
explain
axail resolution is determined by pulse length
shorter pulses have better axial resolution
the 3MHz one has the best axial resolution, which means the 3MHz pulse must be shorter then the 5MHz pulse
since 3MHz sound has a longer wavelength than 5MHz sound, the only way that the 3MHz pulse is shorter is if the 3MHz transducer rings less
thus the 3MHz pulse has fewer cycles than the 5MHz pulse
the ability to distinguish two structures lying close together is called:
resolution
the ability to distinguish two structures lying closes together front-to-back is called:
axial, longitudinal, range, radial, or depth resolution
the ability to distinguish two structures lying close together side by side is called:
lateral, angular, transverse, or azimuthal resolution
