Physics Ch. 13 & 14 Flashcards
The slope of the electrical spike line determines the ______ of the sound beam
steer direction
How many elements are in a mechanical transducer
one single, circular, disc shaped
If the spike line is straight (no curve) the sound beam will be
unfocused
Focusing may occur during
both transmission and reception
Phased array always means ______ or “multi focus”
adjustable
The _____ pattern controls the steering of the beam and the ______ pattern controls the focusing of the beam
slope, curved
If the right electrical spike excites the right active element first, followed by the next and so on, the beam will be steered in what direction
left
Can focusing only be performed during transmission
no
What type of transducer creates a trapezoidal-shaped image
vector
What type of transducer is comprised of multiple ring-shaped elements
annular
What type of transducer creates a rectangular-shaped image
linear sequential
What type of transducer creates a blunted sector-shaped image
curvilinear
With which type of transducer with a damaged PZT crystal results in a horizontal band of dropout in the image
annular
What affect is there on the ultrasound image if there is one crystal damaged, using a mechanical transducer
entire image is lost
Temporal resolution is determined by
frame rate
Two sonographer-controlled settings of an ultrasound system that determine frame rate are:
imaging depth, # pulses per picture
Deep imaging will result in a _______ go-return time, a ______ T frame, a _____ frame rate and ______ temporal resolution
long, longer, lower, inferior
What results from using multi-focus: pulses per scan line, t frame, frame rate, temporal resolution, lateral resolution
many, longer, lower, inferior, improved
Use of a narrower sector will result in a _____ frame rate
higher
High line density will result in _____ pulses per frame, ______ frame rate, _____ temporal resolution and ______ spatial resolution
more, lower, inferior, superior
time frame x frame rate=
1
Time frame and frame rate are _____ related
inversely
What is the frame rate if each image of the ultrasound system is created in 0.02 sec (1/50 sec)
50 Hz
An annular phased array transducer uses ______ steering and _____ focusing
mechanical, beam
Name 3 things that the pulser determines
amplitude, PRP, PRF
During transmission transforms electrical energy into acoustic energy and during reception, converts acoustic energy into electrical energy
transducer
Maintains and organizes the proper timing and interaction of the system’s components
master synchronizer
Transforms the electrical signals from the transducer into a form suitable for display
receiver
Archives the ultrasound studied
storage
Presents processed data
Display
Determines the amplitude, PRP, PRF
pulser
Determines the firing delay patterns for phased array systems
Beam former
Increasing ______ is the most common to improve (increase) the signal-to-noise ratio
output power
What are the 5 operations of the receiver (in appropriate order)
amplification, compensation, compression, demodulation, reject
Are all electrical signals in the receiver affected identically by amplification
yes
Compensation is also known as ______ compensation, ______ gain compensation and _____ gain
time-gain, depth, swept
Regarding the TGC curve, what is the region where compensation corrects for the effects of increasing attenuation that result from increasing path length (depth)
slope
What is the function of the receiver that keeps an image’s gray scale content within the range of detection of the human eye
compression
What are the 2 processes that occur during demodulation
rectification, smoothing/enveloping
What effect does demodulation have on the ultrasound image
none
The rejection function affects ______ echoes, regardless of their location
low-level
Based on the ALARA principle when modifications to either output power or receiver gain can improve the diagnostic quality of an image: if an image is too dark you should first increase _______
receiver gain
Compensation creates an image that is uniformly bright from
top to bottom
A ______ is made up of a single PZT active element in the transducer, the electronics in the beam former/pulser and the wire that connects them
channel
Does the beam former function with array transducers during transmission, reception, or both
both
The beam former adjusts electrical spike voltages to reduce lobe artifacts in a process called
apodization
Lateral resolution improves with
multi-focusing
Spatial resolution improves with
higher line density
What form of resolution improves when frame rate increases
temporal (directly related)
What is consistent with improved temporal resolution
frame rate
A sonographer adjusts an ultrasound scan to double the depth of view from 5cm to 10cm. What happens to the frame rate
It is halved
A sonographer adjusts an ultrasound scan to double the depth of view from 5 cm to 10 cm. Is the frame rate remains the same, which one of the following also occurs
narrow sector
A sonographer adjusts an ultrasound machine to change the sector size from 90 to 45 degrees. Nothing else changes. What happens to the frame rate
Is is doubled
A sonographer adjusts an ultrasound system to change the sector size from 90 to 45 degrees. The frame rate was unchanged. What else must have happened
line density was doubled
A sonographer, using a phased array ultrasound system, turns off the multi-focus feature. What is the most likely consequence of this action
temporal resolution improves
A sonographer increases the line density from 1 line per degree of sector to 3 lines per degree of sector. What is the most likely consequence of this action
temporal resolution decreases
A sonographer reduces the sector angle from 90 degrees to 30 degrees. At the same time, the ultrasound system automatically increases the line density from 1 line per degree to two lines per degree. No other changes are made. What will happen to the frame rate
increases
A sonographer reduces the sector angle from 90 degrees to 30 degrees. At the same time, the ultrasound system automatically increases the line density from 1 line per degree to 3 lines per degree. No other changes are made. What will happen to temporal resolution
remains unchanged
What is most important in determining the frame rate of a system
speed of sound in the medium
What is the frame rate if each image of the ultrasound system is created in 0.02 sec (1/50 sec)
50 Hz
What is the time needed to make a single image if the frame rate of an ultrasound system is 20 Hz
0.05 s
T/F. The critical factor in determining frame rate, line density, and imaging depth is the transducer style
False, time
T/F. The number of lines per frame and the frame rate determine the frequency
False, PRF
T/F. The number of lines per frame and frame rate determine the PRF
true
T/F. If the imaging depth of a scan is 15cm and there are 100 lines in the image, then the number of pulses making up the scan is 100
true
T/F. If 100 scan lines make up an image and the frame rate is 30 per second, then the system’s PRF is 3000 Hz
true
When the frame rate is 30 Hz, how long does it take to create a frame
1/30 sec
Under certain conditions, an ultrasound system creates each image in 0.01 seconds. What is the frame rate
100 Hz
What is the fundamental limitation of temporal resolution
speed of sound in the medium
This type of pulser generates a constant electrical signal in the form of a sine wave
continuous wave
This type of pulser generates a single electrical spike, which ultimately creates a single sound pulse
pulsed wave, single crystal
This type of pulser generates numerous electrical spikes, which ultimately create a single sound pulse
pulsed wave, phased array
The acoustic power of a sound beam emitted from a transducer is determined by the _____ of the pulser’s signal
voltage
T/F. Amplification processes all reflected signals in a similar manner
true
T/F. Compensation processes all reflected signals in a similar manner
false, barely compensated from shallow
