In soft tissue, if the frequency of a wave is increased the Propagation Speed (PS) will...
- correct answer. Remain the Same because stiffness and density affect Propagation
Speed.
What is the audible range? - correct answer. 20-20,000Hz
>20,000Hz=Ultrasound
Frequency is measured in - correct answer. Hertz (Hz)
is
Cycles per Second
Not affected by sonographer
Increase Frequency; Decrease Depth
A period is the length of time it takes for - correct answer. one complete wavelength to
pass a fixed point
PRP is determined by - correct answer. Transmit time and receive time.
Period is measured in - correct answer. Time (μs)
When the sonographer changes the imaging depth what parameters are changed? -
correct answer. PRP, PRF, Duty Factor
What is duty factor? - correct answer. The percentage or fraction of time that the
system is transmitting a pulse (Time Sound is ON or ON-Time).
Propagation Speed in SOFT TISSUE - correct answer. 1.54 mm/μs
(1540 m/sec)
Unit of measurement for Pulse Duration, Duty Factor, PRP, and Period - correct
answer. Time, (μs)
Pulse duration is determined by - correct answer. Sound Source Only
Pulse Duration is controlled by - correct answer. the ultrasound system and
transducer
Pulse Duration Formula - correct answer. pulse duration (μs) = # cycles in
pulse/frequency(MHz)
PD= Number of cycles in Pulse/ Frequency(Hz)
,Spatial Pulse Length (SPL) (measurement) - correct answer. The distance that a
pulse occupies in space from the start to the end of a pulse.
(mm)
Typical values for spatial pulse length in soft tissue. - correct answer. 0.1 to 1.0 mm
Spatial pulse length is determined by - correct answer. sound source and medium
Spatial Pulse Length is directly proportional to - correct answer. the Number of Cycles
in the Pulse
and
the Wavelength
(Directly Proportional means that increased SPL will increase both the number of cycles
in the pulse and the wavelength if increased).
Spatial pulse length is inversely proportional to - correct answer. Frequency (MHz)
(Inversely Proportional means that increased SPL will lower frequency. This is because
axial resolution is better with lower frequency)
Pulse Duration (PD) - correct answer. The actual time from the start of a pulse to the
end of that pulse; a single transmit, talking, or "on" time.
Time the pulse is on typically measured in (ms).
Pulse Length - correct answer. The distance of the pulse start to end or the
duration or length of a single pulse
Pulse Length is typically measured in (mm).
the ability of an object to resist compression and relates to the hardness of a medium? -
correct answer. Stiffness.
Think:
↑ Stiffness ↑ Speed
↓ Density ↑ Speed
An increase in pulse repetition frequency would lead to: - correct answer. Increasing
pulse repetition frequency, increases duty factor.
↑ PRF ↑ Duty Factor
Which of the following would have the highest propagation speed? - correct answer.
Bone has the highest propagation speed, at 2000-4000 m/s.
What has the lowest propagation speed? - correct answer. air technically has the
lowest propagation speed at 300 m/s
, Which has the Slowest Propagation Speed?
Water
Soft Tissue
Bone
Lung tissue - correct answer. Lung Tissue
As imaging depth increases, the pulse repetition frequency (PRF) must: - correct
answer. Decrease
As imaging depth increase, pulse repeition freqency (PRF) decreases.
↑ Imaging Depth ↓ PRF
What describes the amount of refraction that occurs at an interface? - correct answer.
Snell's law
Refraction: the redirection of the transmitted sound beam
Snell's law describes the angle of transmission at an interface based on the angle of
incidence and the propagation speeds of the two media.
Pressure is typically expressed in: - correct answer. Pascals (Pa)
The typical range of frequency for diagnostic ultrasound imaging is - correct answer.
1-20 Mhz is the typical range of frequency for diagnostic ultrasound imaging.
The attentuation coefficient in soft tissue is equal to: - correct answer. Attentuation
Coeffcient = 1/2 (one half of the frequency in soft tissue)
The attentuation coeffcient (in dB/cm) is the rate at which sound is attentuated per unit
depth.
Micro is denoted as: - correct answer. Micro is denoted as millionth (µ)
What is described as the distance over which one cycle occurs? - correct answer.
Wavelength is distance over which one cycle occurs, or the distance from the beginning
of one cycle to the end of the same cycle.
Remember, it asks for distance over which one cycle occurs.
Stiffness and propagation speed are - correct answer. Directly Related
Also remember:
↑ Stiffness ↑ Speed
↓ Density ↑ Speed
- correct answer. Remain the Same because stiffness and density affect Propagation
Speed.
What is the audible range? - correct answer. 20-20,000Hz
>20,000Hz=Ultrasound
Frequency is measured in - correct answer. Hertz (Hz)
is
Cycles per Second
Not affected by sonographer
Increase Frequency; Decrease Depth
A period is the length of time it takes for - correct answer. one complete wavelength to
pass a fixed point
PRP is determined by - correct answer. Transmit time and receive time.
Period is measured in - correct answer. Time (μs)
When the sonographer changes the imaging depth what parameters are changed? -
correct answer. PRP, PRF, Duty Factor
What is duty factor? - correct answer. The percentage or fraction of time that the
system is transmitting a pulse (Time Sound is ON or ON-Time).
Propagation Speed in SOFT TISSUE - correct answer. 1.54 mm/μs
(1540 m/sec)
Unit of measurement for Pulse Duration, Duty Factor, PRP, and Period - correct
answer. Time, (μs)
Pulse duration is determined by - correct answer. Sound Source Only
Pulse Duration is controlled by - correct answer. the ultrasound system and
transducer
Pulse Duration Formula - correct answer. pulse duration (μs) = # cycles in
pulse/frequency(MHz)
PD= Number of cycles in Pulse/ Frequency(Hz)
,Spatial Pulse Length (SPL) (measurement) - correct answer. The distance that a
pulse occupies in space from the start to the end of a pulse.
(mm)
Typical values for spatial pulse length in soft tissue. - correct answer. 0.1 to 1.0 mm
Spatial pulse length is determined by - correct answer. sound source and medium
Spatial Pulse Length is directly proportional to - correct answer. the Number of Cycles
in the Pulse
and
the Wavelength
(Directly Proportional means that increased SPL will increase both the number of cycles
in the pulse and the wavelength if increased).
Spatial pulse length is inversely proportional to - correct answer. Frequency (MHz)
(Inversely Proportional means that increased SPL will lower frequency. This is because
axial resolution is better with lower frequency)
Pulse Duration (PD) - correct answer. The actual time from the start of a pulse to the
end of that pulse; a single transmit, talking, or "on" time.
Time the pulse is on typically measured in (ms).
Pulse Length - correct answer. The distance of the pulse start to end or the
duration or length of a single pulse
Pulse Length is typically measured in (mm).
the ability of an object to resist compression and relates to the hardness of a medium? -
correct answer. Stiffness.
Think:
↑ Stiffness ↑ Speed
↓ Density ↑ Speed
An increase in pulse repetition frequency would lead to: - correct answer. Increasing
pulse repetition frequency, increases duty factor.
↑ PRF ↑ Duty Factor
Which of the following would have the highest propagation speed? - correct answer.
Bone has the highest propagation speed, at 2000-4000 m/s.
What has the lowest propagation speed? - correct answer. air technically has the
lowest propagation speed at 300 m/s
, Which has the Slowest Propagation Speed?
Water
Soft Tissue
Bone
Lung tissue - correct answer. Lung Tissue
As imaging depth increases, the pulse repetition frequency (PRF) must: - correct
answer. Decrease
As imaging depth increase, pulse repeition freqency (PRF) decreases.
↑ Imaging Depth ↓ PRF
What describes the amount of refraction that occurs at an interface? - correct answer.
Snell's law
Refraction: the redirection of the transmitted sound beam
Snell's law describes the angle of transmission at an interface based on the angle of
incidence and the propagation speeds of the two media.
Pressure is typically expressed in: - correct answer. Pascals (Pa)
The typical range of frequency for diagnostic ultrasound imaging is - correct answer.
1-20 Mhz is the typical range of frequency for diagnostic ultrasound imaging.
The attentuation coefficient in soft tissue is equal to: - correct answer. Attentuation
Coeffcient = 1/2 (one half of the frequency in soft tissue)
The attentuation coeffcient (in dB/cm) is the rate at which sound is attentuated per unit
depth.
Micro is denoted as: - correct answer. Micro is denoted as millionth (µ)
What is described as the distance over which one cycle occurs? - correct answer.
Wavelength is distance over which one cycle occurs, or the distance from the beginning
of one cycle to the end of the same cycle.
Remember, it asks for distance over which one cycle occurs.
Stiffness and propagation speed are - correct answer. Directly Related
Also remember:
↑ Stiffness ↑ Speed
↓ Density ↑ Speed
