Term
|
Definition
1. the number of vibrations that a molecule makes per second. 2. the number of times the cycle is repeated each second |
|
|
Term
|
Definition
| Those pressure changes that the human ear can detect. |
|
|
Term
What is the frequency of an audible sound wave? |
|
Definition
20-20,000 cycles/sec. (Hz) |
|
|
Term
|
Definition
| the transmittal to distant regions remote from the sound source. |
|
|
Term
|
Definition
Mechanical waves with higher frequencies than can be heard by the human ear |
|
|
Term
What is the frequency of an ultrasound wave? |
|
Definition
|
|
Term
|
Definition
Mechanical waves with frequencies lower than can be heard by a human ear |
|
|
Term
What are the frequencies of infrasound? |
|
Definition
|
|
Term
|
Definition
a high-pressure region formed by a wave |
|
|
Term
|
Definition
A low-pressure region formed by a wave |
|
|
Term
What are the two basic types of sound waves? |
|
Definition
longitudinal and transverse |
|
|
Term
Define: longitudinal waves |
|
Definition
particles move along the direction of the wave energy |
|
|
Term
|
Definition
particles move perpendicular to the wave energy (ripples in a pond) |
|
|
Term
What type of wave is a US wave? |
|
Definition
|
|
Term
|
Definition
| The length of one comple wave cycle |
|
|
Term
What is the symbol for wavelength? |
|
Definition
|
|
Term
| What are the units for wavelength? |
|
Definition
um, mm, cm, m (distance measure) |
|
|
Term
|
Definition
| The change in magnitude of a wave. |
|
|
Term
|
Definition
1. The time necessary for one complete cycle 2. the time between two successive compression zones |
|
|
Term
| What is the symbol for period? |
|
Definition
|
|
Term
| What are the units for the period? |
|
Definition
|
|
Term
What is the symbol for frequency? |
|
Definition
|
|
Term
| What are the units for frequency? |
|
Definition
|
|
Term
| How are the period and frequency of a wave related? |
|
Definition
1. frequency is the inverse of the period. 2. f= 1/tao 3. tao = 1/f |
|
|
Term
|
Definition
| Hz is the number of cycles per second |
|
|
Term
| Calc the period of a wave with a frequency of 3,000,000 Hz. |
|
Definition
|
|
Term
| Calc. the frequency of a wave with a period of 5 x 10 -7 s. |
|
Definition
|
|
Term
Define: Acoustic velocity |
|
Definition
| The speed at which a wave propagates through a medium |
|
|
Term
Define: particle velocity |
|
Definition
| the speed at which particles vibrate back and forth across their average postion. |
|
|
Term
|
Definition
| the ability to return to it's original shape and volume |
|
|
Term
|
Definition
| the mass of a medium per unit volume |
|
|
Term
| If all other physical properties remain the same; if density increases what happens to the rate of sound propagation? |
|
Definition
| The sound propagation rate decreases. |
|
|
Term
| What is the relationship between the velocity of sound in a medium and density? (mathematical) |
|
Definition
the velocity of sound in a medium is inversely proportional to the square root of the density of the medium. |
|
|
Term
|
Definition
the fractional decrease in volume when pressure is applied to the material. |
|
|
Term
| What is the symbol for compressibility? |
|
Definition
|
|
Term
| What is the relationship between compressibility and the velocity of sound in a medium? |
|
Definition
| the velocity of sound is is inversely proportional to the square root of the compressibility of the medium. |
|
|
Term
|
Definition
| The negative ratio of stress and strain. Where stress is the force per unit area applied to a object and strain is the fractional change in volume of the object. |
|
|
Term
| What is the symbol for bulk modulus? |
|
Definition
|
|
Term
| What is the relationship between B, K & c? |
|
Definition
| As B increases and K decreases then c increases |
|
|
Term
Define: Diffuse Reflection |
|
Definition
| Multiple angles of reflection caused by a large, rough surface interface |
|
|
Term
| What is the relationship between compressibility and density? |
|
Definition
| They are interdependent. A change in density is often coupled with a larger and opposing change in compressibility. |
|
|
Term
What is the velocity of sound through: soft tissue |
|
Definition
|
|
Term
What is the velocity of sound through: liver |
|
Definition
|
|
Term
What is the velocity of sound through: muscle |
|
Definition
|
|
Term
What is the velocity of sound through: fat |
|
Definition
|
|
Term
What is the velocity of sound through: brain |
|
Definition
|
|
Term
What is the velocity of sound through: kidney |
|
Definition
|
|
Term
What is the velocity of sound through: spleen |
|
Definition
|
|
Term
What is the velocity of sound through: blood |
|
Definition
|
|
Term
What is the velocity of sound through: bone |
|
Definition
|
|
Term
What is the velocity of sound through: lung |
|
Definition
|
|
Term
What is the velocity of sound through: air |
|
Definition
|
|
Term
What is the velocity of sound through: water |
|
Definition
|
|
Term
T or F in the transmission of sound, soft tissue behaves similarly to liquid |
|
Definition
|
|
Term
What is the relationship between density, velocity and compressibility? |
|
Definition
| As density increases so does velocity (because of low compressibility) |
|
|
Term
| The average speed in soft itssue is: |
|
Definition
|
|
Term
| Does velocity depend on temperature? |
|
Definition
| Yes, but it is not significant in clinical imaging. |
|
|
Term
| How are frequency, wavelength and velocity related mathematically? |
|
Definition
| velocity equals wavelength times frequency |
|
|
Term
| If the frequency increases the wavelength __________ |
|
Definition
|
|
Term
| What is the wavelength in tissue of a 2.5 MHz source? |
|
Definition
|
|
Term
| If the frequency is 1 MHz what is the wavelength (in ST)? |
|
Definition
|
|
Term
|
Definition
| Non-specular reflection that gives us internal texture of organs |
|
|
Term
| If the frequency is 2.5 MHz what is the wavelength (in ST)? |
|
Definition
|
|
Term
| If the frequency is 3.5 MHz what is the wavelength (in ST)? |
|
Definition
|
|
Term
| If the frequency is 5 MHz what is the wavelength (in ST)? |
|
Definition
|
|
Term
| If the frequency is 7.5 MHz what is the wavelength (in ST)? |
|
Definition
|
|
Term
| If the frequency is 10 MHz what is the wavelength (in ST)? |
|
Definition
|
|
Term
| If the frequency is 15 MHz what is the wavelength (in ST)? |
|
Definition
|
|
Term
| If the frequency is 20 MHz what is the wavelength (in ST)? |
|
Definition
|
|
Term
|
Definition
| the ability to distinguish objects that are located close together as separate entities |
|
|
Term
| Are us images are based on reflected or transmitted energy? |
|
Definition
|
|
Term
| What is the job of the transducer? |
|
Definition
| To transmit the US wave and detect the reflected energy |
|
|
Term
Attenuation is affected by all of the following EXCEPT reflection, refraction, scattering, diffraction, divergence, interference, absorption |
|
Definition
interference (reflection is often treated separately) |
|
|
Term
|
Definition
| reduction in the intensity of the beam |
|
|
Term
|
Definition
a sound beam directed at 90 degrees (right angle) |
|
|
Term
Define: specular reflector |
|
Definition
| smooth interface and larger the the width of the ultrasound beam |
|
|
Term
| If you are not at a normal incidence, how are the angle of reflection and angle incidence related? |
|
Definition
|
|
Term
| How can you maximize the reflected echo? |
|
Definition
| Orient the transducer so that the generated sound beam strikes the interface at a right angle |
|
|
Term
Define: acoustic impedance |
|
Definition
1. similar to momentum but not looking at individual molecules, but at their concerted action 2. a measure of the resistance to sound passing through the medium |
|
|
Term
| What is the symbol for acoustic impedance? |
|
Definition
|
|
Term
| What is the mathematical formula for acoustic impedence? |
|
Definition
| acoustic impedence equals velocity times density |
|
|
Term
| Which has a greater magnitude? Scattered or Specular reflections? |
|
Definition
|
|
Term
| What are the units for acoustic impedence? |
|
Definition
|
|
Term
| What is Z of ST which has a density of 1060 kg/m3? |
|
Definition
|
|
Term
| If a material is high density there will be high or low acoustic impedences? |
|
Definition
|
|
Term
| What property allows visualization of ST structures at a biological interface? |
|
Definition
|
|
Term
| What is the mathematical formula for the reflection coefficient? |
|
Definition
| the reflection coefficient is equal to the acoustic impedence of material 2 (distal) minus the acoustic impedence of material 1 (proximal) divided by theacoustic impedence of material 2 (distal) plus the acoustic impedence of material 1 (proximal) squared. |
|
|
Term
| Why do fluid region produce weak signals? |
|
Definition
| They do not have scattering centers and therefore produce weak signals. |
|
|
Term
| How do you find the percentage reflection (%R)? |
|
Definition
| Multiply the reflection coefficient by 100. |
|
|
Term
| What is the formula for the transmission coefficient? |
|
Definition
1. 1- the reflection coefficient 2. 4 times the acoustic impedence of material 2 (distal) multiplied by the acoustic impedence of material 1 (proximal) divided by the acoustic impedence of material 2 (distal)plus the acoustic impedence of material 1 (proximal) squared |
|
|
Term
| How can you calculate the percentage transmission? |
|
Definition
1. 100 - the reflection coefficient 2. the transmission coefficient times 100 |
|
|
Term
| Does frequency effect the transmission and reflection coefficients? |
|
Definition
| No, they are independent of each other. |
|
|
Term
| As the angle of incidence increase the reflection coefficient: decreases or increases? |
|
Definition
|
|
Term
If the acoustic impedence in large then: %R will be large and % T will be large %R will be small and % T will be large %R will be large and % T will be small %R will be small and % T will be small |
|
Definition
| %R will be large and % T will be small |
|
|
Term
| Calculate the %R for a bone tissue interface using Table 1-4. |
|
Definition
|
|
Term
| Calc. %T for a ST-bone interface using table 1-4. |
|
Definition
|
|
Term
| Calc. %R for an air-tissue interface using table 1-4. Calc %T. |
|
Definition
|
|
Term
|
Definition
| functional part of the organ |
|
|
Term
|
Definition
| Increased US signals as compared to the surrounding tissue |
|
|
Term
|
Definition
| Decreased us signals as compared to the surrounding tissue. |
|
|
Term
Define Rayleigh Scattering |
|
Definition
Scattering by small particles whose dimensions are much smaller than the wavelength. |
|
|
Term
True or False nonspecular reflection have a strong frequency dependence. |
|
Definition
|
|
Term
True or False Specular reflectors have a strong frequency dependence |
|
Definition
|
|
Term
|
Definition
| The bending of sound waves that happens when the wave strikes an interface and the incident angle is not 90 degrees. |
|
|
Term
|
Definition
1. the law that describes how sound waves are refracted. 2. Relates the angle of transmission to the relative velocities of sound in the 2 media |
|
|
Term
| What type of refraction occurs when the velocity in the incident medium is greater than the velocity in the transmitted medium? |
|
Definition
| the sound wave is bent towards the normal |
|
|
Term
| What happens when the velocity in the incident medium is less than the sound wave in the transmitted medium? |
|
Definition
| The sound wave is bent away from normal. |
|
|
Term
True or False Refraction can cause artifacts in images |
|
Definition
|
|
Term
|
Definition
| the divergence of the sound beam as it moves away from the source. |
|
|
Term
|
Definition
| the superposition of sound waves |
|
|
Term
Define Constructive interference |
|
Definition
| Results in an increase in amplitude |
|
|
Term
| If 2 waves are in phase, what type of interference will you have? |
|
Definition
|
|
Term
Define Destructive interference |
|
Definition
| Results in a decrease in amplitude |
|
|
Term
| If 2 waves are out of phase, it results in what type of interference |
|
Definition
|
|
Term
|
Definition
1. The (only) process by which sound energy is dissipated in a medium 2. the process by which us energy is transformed into other energy forms (heat) |
|
|
Term
| What 3 things influence absorption? |
|
Definition
| f, viscosity, and relaxation time of the medium |
|
|
Term
| What is the relationship between absorption and frequency? |
|
Definition
| They are directly related, if frequency doubles, so does absorption |
|
|
Term
| What are the Units of acoustic pressure? |
|
Definition
| mm Hg, pascal, atmospheres |
|
|
Term
| What are the units of particle density |
|
Definition
|
|
