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Questions and Answers
What is the relationship between duty factor and pulse repetition frequency (PRF)?
What is the relationship between duty factor and pulse repetition frequency (PRF)?
If the pulse duration is 3 microseconds and the pulse repetition period is 0.003 seconds, what is the duty factor?
If the pulse duration is 3 microseconds and the pulse repetition period is 0.003 seconds, what is the duty factor?
How does increasing imaging depth affect the duty factor?
How does increasing imaging depth affect the duty factor?
If a continuous wave operates at 10 MHz and is pulsed with a duty factor of 0.2, what happens to the frequency?
If a continuous wave operates at 10 MHz and is pulsed with a duty factor of 0.2, what happens to the frequency?
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Which of the following correctly describes the effect of decreasing the maximum imaging depth on the pulse repetition period (PRP)?
Which of the following correctly describes the effect of decreasing the maximum imaging depth on the pulse repetition period (PRP)?
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What happens to pulse repetition frequency when imaging depth is increased?
What happens to pulse repetition frequency when imaging depth is increased?
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Which of the following statements is true regarding pulse repetition period?
Which of the following statements is true regarding pulse repetition period?
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How does increasing the depth of imaging affect listening time?
How does increasing the depth of imaging affect listening time?
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What is the relationship between spatial pulse length and wavelength?
What is the relationship between spatial pulse length and wavelength?
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What determines the pulse repetition frequency in ultrasound imaging?
What determines the pulse repetition frequency in ultrasound imaging?
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If a sonographer decreases the imaging depth, what effect does this have on pulse repetition frequency?
If a sonographer decreases the imaging depth, what effect does this have on pulse repetition frequency?
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Which statement best describes duty factor in relation to pulse repetition frequency?
Which statement best describes duty factor in relation to pulse repetition frequency?
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What is the primary function of the depth control button in ultrasound systems?
What is the primary function of the depth control button in ultrasound systems?
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What is the relationship between pulse repetition period (PRP) and pulse repetition frequency (PRF)?
What is the relationship between pulse repetition period (PRP) and pulse repetition frequency (PRF)?
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If the duty factor of a transducer is 0.004, what does this indicate about its performance?
If the duty factor of a transducer is 0.004, what does this indicate about its performance?
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What is the maximum value of duty factor for continuous wave (CW) ultrasound?
What is the maximum value of duty factor for continuous wave (CW) ultrasound?
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Calculate the duty factor for a pulse repetition period of 40 microseconds and a pulse duration of 2 microseconds.
Calculate the duty factor for a pulse repetition period of 40 microseconds and a pulse duration of 2 microseconds.
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How does the duty factor change with varying depths in ultrasound imaging?
How does the duty factor change with varying depths in ultrasound imaging?
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If a machine has a pulse repetition frequency (PRF) of 10 Hz, what is the corresponding pulse repetition period (PRP)?
If a machine has a pulse repetition frequency (PRF) of 10 Hz, what is the corresponding pulse repetition period (PRP)?
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What does a low duty factor imply about the ultrasound machine's operation?
What does a low duty factor imply about the ultrasound machine's operation?
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Which of the following correctly describes the duty factor formula?
Which of the following correctly describes the duty factor formula?
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Study Notes
Pulsed Waves
- Pulsed waves differ from continuous waves. Continuous waves produce a constant signal, while pulsed waves emit short bursts of acoustic energy.
- Diagnostic ultrasound uses pulsed waves to create images
- Pulsed wave parameters are different from other types of waves
- Pulsed waves can be characterized using several new parameters.
Describing Pulsed Waves
- Seven parameters describe continuous waves, but pulsed waves need additional parameters
- The seven parameters of continuous waves are not sufficient to describe pulsed waves, new terms are required.
Pulsed Ultrasound
- Continuous wave sound creates no anatomic images in diagnostic ultrasound - Pulsed ultrasound creates images
- Imaging systems use short bursts (pulses) of acoustic energy
What is Pulsed Sound?
- A pulsed ultrasound is a collection of cycles that creates a pulse - It contains a beginning and an end - A pulse is a single unit of energy
Pulsed Ultrasound Has 2 Components
- Transmit time: the transducer is sending a pulse
- Receive time: the transducer is not sending a pulse, but waiting for reflections
- The machine has two phases: emit a pulse and receive a pulse.
A Pulse is a Pulse...
- The characteristics of a pulse are determined by the source (machine/transducer), not the user
- The characteristics of the pulse signal can't be changed once it has been sent
Parameters Describe Pulsed Sound
- Five parameters describe the characteristics of pulsed sounds - Pulse duration, spatial pulse length, pulse repetition period, pulse repetition frequency and duty factor.
Pulse Duration
- The time from the start of a pulse to the end
- The pulse duration is determined by the ultrasound source.
Spatial Pulse Length
- The length or distance a pulse occupies in space
- Directly proportional to the wavelength, longer wavelength means longer spatial pulse length.
Pulse Repetition Period (PRP)
- PRP is the time between the start of one pulse a the start of the next pulse
- The time between the start of one pulse and the start of the next - can be adjusted by the user
Pulse Repetition Period & Depth
- Increasing depth increases the time it takes for the sound beam to return.
- Increased depth correlates directly with incresed repetition period
PRP is Directly Related to Depth
- Increasing depth increases PRP
- Increasing listening time increases PRP
Pulse Repetition Period (PRP) & Depth / Directly Related
- Increasing depth increases the time taken for a sound beam to return
- PRP is directly related to depth and indirectly proportional to the frequency
When You Decrease Depth...
- Decreasing depth results in a closer view (zoomed in) and a shorter time, also more frequent pulses
Shallow Imaging
- Deeper imaging requires longer listening times
- Shallower imaging requires less listening time
Deep Imaging
- Deeper imaging requires more listening time
- Shallower imaging requires less listening time
Pulse Repetition Frequency (PRF)
- PRF is the number of pulses emitted each second
- The number of pulses an ultrasound system transmits into the body each second - determined by the ultrasound machine.
Pulse Repetition Frequency (PRF)
- More shallow (shallower) scanning will require a higher PRF (pulse repetition frequency rate). Deeper (deeper) scanning will require a lower PRF and longer listening time.
Pulse Repetition Frequency (PRF) & Depth / Inversely Related
- PRF is the number of pulses transmitted into a body each second.
- PRF is inversely related to depth
Relationship of PRP & PRF
- PRP and PRF are reciprocals. PRP (time) multiplied by PRF (frequency) equals 1
- They have an inverse relationship
Duty Factor
- Duty factor is the percentage or fraction of time during which the ultrasound machine produces a pulse or transmits sound.
- The duty cycle is equal to the pulse duration divided by the pulse repetition period and then multiplied by 100
- Clinically, the imaging of duty factors is in the range of 0.2% to 0.5%.
Duty Factor
- The percentage or fraction of a period in which a device sends a pulse - the amount of time a pulse is sent compared to the total time
Duty Factor
- Duty factor is the percentage of time the system produces a pulse - High duty factors mean pulses are frequently produced.
Duty Factor
- A duty factor is one of the factors that make up pulsed signals - Duty factor is unrelated to frequency - The duty factor is higher for shallower imagining, and lower for deeper imagines.
Questions
- What is the duty factor?: The duty factor of a wave is the ratio of pulse duration to pulse repetition period multiplied by 100 - Calculated as pulse duration divided by pulse repetition period.
Duty Factor
- Depth change does not change the Duty Factor
- Duty factor is determined by the ultrasound machine's source
Duty Factor
- Duty factor is inversely related to depth
- Shallower imaging requires a higher duty factor (more pulses) - Deeper imaging requires a lower duty factor (fewer pulses).
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Description
Explore the fundamental differences between pulsed and continuous waves in ultrasound technology. This quiz covers key parameters unique to pulsed waves essential for diagnostic imaging. Dive into how imaging systems utilize short bursts of acoustic energy to create detailed anatomical images.
