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Questions and Answers
What characterizes rarefactions in sound waves?
What characterizes rarefactions in sound waves?
Which term describes the time required to complete a single cycle of a sound wave?
Which term describes the time required to complete a single cycle of a sound wave?
Which acoustic variable indicates the concentration of force in a specific area?
Which acoustic variable indicates the concentration of force in a specific area?
What happens to sound waves when they are in phase?
What happens to sound waves when they are in phase?
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What does the frequency of a sound wave measure?
What does the frequency of a sound wave measure?
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Which acoustic parameter measures the maximum deviation from the average value of an acoustic variable?
Which acoustic parameter measures the maximum deviation from the average value of an acoustic variable?
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What does propagation speed refer to in sound waves?
What does propagation speed refer to in sound waves?
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What is the correct relationship between the amplitude and intensity of a sound wave?
What is the correct relationship between the amplitude and intensity of a sound wave?
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What does the x-axis represent in an m-mode ultrasound through echocardiography?
What does the x-axis represent in an m-mode ultrasound through echocardiography?
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Which statement best describes a direct relationship?
Which statement best describes a direct relationship?
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If factor A is tripled, how does this impact factor B if they are reciprocals?
If factor A is tripled, how does this impact factor B if they are reciprocals?
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Which of the following is an example of an inverse relationship?
Which of the following is an example of an inverse relationship?
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In a reciprocal relationship, what occurs when one factor is increased by 8 times?
In a reciprocal relationship, what occurs when one factor is increased by 8 times?
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What is represented on the y-axis of a spectral Doppler tracing?
What is represented on the y-axis of a spectral Doppler tracing?
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Which of the following is a true statement about reciprocal relationships?
Which of the following is a true statement about reciprocal relationships?
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Which example best illustrates an unrelated relationship?
Which example best illustrates an unrelated relationship?
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What happens to factor C when factor D, a reciprocal, is doubled?
What happens to factor C when factor D, a reciprocal, is doubled?
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Why is it necessary to include units when stating numerical values?
Why is it necessary to include units when stating numerical values?
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Which prefix corresponds to a factor of 10^-3 in the metric system?
Which prefix corresponds to a factor of 10^-3 in the metric system?
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What is the scientific notation for the number 0.00000123?
What is the scientific notation for the number 0.00000123?
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Which of the following units is a base metric unit?
Which of the following units is a base metric unit?
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How should the number 5 kilometers be expressed in millimeters?
How should the number 5 kilometers be expressed in millimeters?
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What is the purpose of using scientific notation?
What is the purpose of using scientific notation?
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What does the acronym 'm' represent in the metric system?
What does the acronym 'm' represent in the metric system?
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What is the wavelength of a sound wave with a frequency of 10 MHz in soft tissue?
What is the wavelength of a sound wave with a frequency of 10 MHz in soft tissue?
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If the frequency of a sound wave in soft tissue is 1 MHz, what is its wavelength?
If the frequency of a sound wave in soft tissue is 1 MHz, what is its wavelength?
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Which of the following statements about wavelength and frequency is correct?
Which of the following statements about wavelength and frequency is correct?
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How can propagation speed be calculated if the distance traveled by sound and the time taken are known?
How can propagation speed be calculated if the distance traveled by sound and the time taken are known?
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Why does high-frequency sound provide better resolution in imaging?
Why does high-frequency sound provide better resolution in imaging?
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What determines the propagation speed of sound in a medium?
What determines the propagation speed of sound in a medium?
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What happens to the wavelength if the frequency of sound in soft tissue increases?
What happens to the wavelength if the frequency of sound in soft tissue increases?
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What is the propagation speed of sound in MRI through soft tissue if a sound wave travels 20 cm in 4 seconds?
What is the propagation speed of sound in MRI through soft tissue if a sound wave travels 20 cm in 4 seconds?
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What is the unit of measurement for power?
What is the unit of measurement for power?
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If the amplitude of a sound wave is increased by a factor of 3, how does the power change?
If the amplitude of a sound wave is increased by a factor of 3, how does the power change?
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What happens to power when the amplitude is decreased by half?
What happens to power when the amplitude is decreased by half?
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Which equation describes the relationship between intensity, power, and beam area?
Which equation describes the relationship between intensity, power, and beam area?
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If the power in a sound beam is doubled while the beam area remains constant, how does the intensity change?
If the power in a sound beam is doubled while the beam area remains constant, how does the intensity change?
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How is intensity related to amplitude?
How is intensity related to amplitude?
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What is a common typical value for ultrasound intensity?
What is a common typical value for ultrasound intensity?
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What does intensity describe in a sound wave?
What does intensity describe in a sound wave?
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What occurs when two waves overlap at the same location and time?
What occurs when two waves overlap at the same location and time?
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When does constructive interference occur?
When does constructive interference occur?
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How does frequency relate to the cycles of a wave?
How does frequency relate to the cycles of a wave?
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What is a primary property of waves of different frequencies at the moment of interference?
What is a primary property of waves of different frequencies at the moment of interference?
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What determines whether a parameter of a sound wave can be changed during ultrasound imaging?
What determines whether a parameter of a sound wave can be changed during ultrasound imaging?
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Which of the following statements about the speed of sound in soft tissue is true?
Which of the following statements about the speed of sound in soft tissue is true?
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What aspect can influence the biologic effects of sound waves?
What aspect can influence the biologic effects of sound waves?
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Which acoustic parameter typically cannot be changed during the operation of a transducer?
Which acoustic parameter typically cannot be changed during the operation of a transducer?
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Study Notes
Ultrasound Physics: Basics
- Ultrasound physics is the study of the physical principles of ultrasound.
- Graphs are used to display relationships between variables in physics and ultrasound.
- The horizontal axis (x-axis) typically represents time and the vertical axis (y-axis) represents velocity.
- In spectral Doppler, the x-axis represents time and the y-axis represents blood velocity.
- M-mode ultrasound uses the x-axis to represent time and the y-axis to represent depth of reflectors.
Relationships in Ultrasound Physics
- Relationships describe the variables' association or proportionality.
- Two items are related or proportional when one item's change affects the other.
- Unrelated items do not have a relationship or dependency.
- Example of unrelated items: Hair color and intelligence.
- Example of directly related items: Clothing size and age of a child. An example of directly proportional variables includes the relationship between the age of a tree and its size.
- Example of indirectly/inversely related items: Golf score and skills. Another example includes a car's gas mileage and its size-- larger cars typically have lower gas mileage.
- Example of reciprocal relationships: two numbers multiplied together result in one (1).
- Example of reciprocals: 2 and 1/2 are reciprocals; 1 and 1/10th are reciprocals; 1/100,000th and 100,000 are reciprocals.
Units and Presentation
- Numerical values must include units.
- Units give meaning to the numerical values.
- Examples of units: inches, feet, miles.
- A unit must be included for the numerical value to be meaningful.
- Any technically correct unit can be used.
- Example: 6 inches tall, 6 feet tall, 6 miles.
- Numerical values must have units (unless percentage or otherwise noted as a unitless number).
Scientific Notation
- Scientific notation simplifies very large or small numbers.
- Example: 0.000000124=1.24 x 10⁻⁷; 1,000,000 = 1.0 x 10⁶.
- It is a shorthand way to express very large or very small numbers.
- Counting zeros is common when expressing numbers in scientific notation.
The Metric System
- The metric system is used to express measurements in science.
- Units of measurement use prefixes to indicate multiples of ten.
- Understanding metric conversions is crucial for ultrasound physics.
- A helpful memory tool is King Henry Doesn't Usually Drink Chocolate Milk, used to remember the order of the prefixes (kilo, hecto, deca, unit, deci, centi, milli).
Converting with Metrics
- Number line conversions are common.
- Determining the number of spaces between prefixes.
- Moving the decimal point based on the calculation helps determine the equivalent value.
- Using the number line can help determine how many spaces exist between the prefix that is present in the number and the prefix to which conversion is being performed.
Ultrasound Physics: Sound
- Sound is a type of wave that carries energy.
- Sound waves must travel through a medium, they cannot travel through a vacuum.
- Sound waves travel in straight lines until they encounter something that changes their direction (like a wall).
- Sound waves are also called acoustic waves.
Properties of Sound Waves
- Sound waves move through different substances or mediums.
- Sound cannot travel through a vacuum—a space that lacks any medium.
- Sound waves travel in straight lines until they interact with objects, materials, or forces that cause them to change their pathway.
Types of Waves
- Transverse waves—particles vibrate perpendicular to wave direction.
- Longitudinal waves—particles vibrate parallel to wave direction.
- Mechanical waves are characterized by the movement of particles in a medium, vibrating back and forth.
- Sound waves are mechanical and longitudinal waves.
Acoustic Variables and Parameters
- Acoustic variables—describes changes in 3 physical characteristics: pressure, density and distance/particle motion, that occur when sound travels through a medium.
- Acoustic parameters—describe features of a sound wave: period, frequency, amplitude, power, intensity, wavelength, propagation speed.
- This is important for understanding acoustic properties of sound waves.
Phase Relationships
- Waves can be in phase (synchronized peaks and troughs) or out of phase.
- Interference—occurs when two waves overlap at the same location and time, producing either constructive or destructive interference.
- Constructive interference results in a larger amplitude than the original waves.
- Destructive interference result in a smaller amplitude than the original waves.
Waves of Different Frequencies
- Frequency—the number of cycles in one second.
- When two waves of different frequencies interfere, the interference can be constructive or destructive at different moments in time.
Acoustic Propagation Properties
- Acoustic Propagation Properties—examine the interaction between a sound wave and the medium through which the wave travels.
Describing Sound Waves and Acoustic Parameters
- Acoustic Parameters—describe features of sound waves (period, frequency, amplitude, power, intensity, wavelength, propagation speed).
- Knowing the units and how parameters are related is important to understanding ultrasound physics.
The Sound Source and Medium
- Sound source relates to the ultrasound system and transducer, which establishes the physical features of sound.
- The quantity or level of some parameters is established by the ultrasound system.
- Some of these levels can be changed by turning a knob on the machine, others cannot.
- The medium is the material through which the sound travels (soft tissue in diagnostic medical sonography).
- The speed of sound in soft tissue is 1540 m/s. This can also be represented as 1.54 km/s (kilometers per second) or 1.54 mm/µs (millimeters per microsecond).
Acoustic Variables
- Acoustic variables—pressure, density, and particle motion—describe the physical characteristics of sound waves.
Other "Bigness" Parameters (Amplitude, Power, Intensity)
- Describing the size, strength or related characteristics of a sound wave.
- amplitude—the difference between the average value and the maximum or minimum value of an acoustic variable; describing the "bigness" or height of a sound wave.
- Power—the rate of energy transfer.
- Intensity—describes how the power is distributed in a sound beam.
Wavelength
- Wavelength (L) describes the distance of one sound wave cycle.
- Wavelength (expressed in mm) is determined by the sound source and the medium through which it travels; it is not typically changed by the sonographer.
- Wavelength and frequency have an inverse relationship.
Propagation Speed
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Propagation speed—the rate at which sound travels through a given medium.
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Propagation speed is a constant when moving through soft tissue.
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Speed of sound is related to the stiffness and density of a medium. Stiffness is a medium's ability to be moved. Density is a medium's weight (directly related to stiffness and greater related to a medium's weight).
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Bulk modulus is the same as stiffness.
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Speed of sound in various mediums or tissues (different speeds).
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Example of speed of sound in different types of tissues (Example: Air—330 m/s; Lung—300-1200 m/s; Fat—1450 m/s; Soft tissue—1540 m/s; Tendon—1850 m/s; Bone—2000-4000 m/s.
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Description
Test your understanding of key concepts related to sound waves and their properties. This quiz covers topics such as rarefactions, frequency, amplitude, and the relationships between various acoustic parameters. Perfect for students studying acoustics or related medical fields.
