Chapter 1-3 Flashcards
Is the conservation of energy theory always true in ultrasound?
No
What kind of interference do inphase waves have?
They have constructive interference
What kind of interference do outphase waves have?
They have destructive interference
What is constructive interference? How does it appear on ultrasound
The compression and infractions line up. The result is a larger amplitude and more hyperechoic appearance.
What is destructive interference? How does it appear on ultrasound
The compression and infractions are opposite. They would be subtracted for a smaller amplitude and hypoechoic appearance.
What does it mean when two things are related in physics?
They can either be directly or inversely proportional
What does it mean when two things are unrelated in physics?
They are not associated with the other option
what is a medium
the material you are scanning through.
what is the source?
the origin of the ultrasound beam
What are the four properties of a soundwave
mechanical, cannot travel through a vaccuum, travels in a straight line, longitudinal wave
what are the three acoustic variables?
Pressure, density, distance.
Define pressure
concentration of force in an area
Define density
the concentration of mass in an area.
what direction is a transverse wave?
perpendicular to the wave travel
What does it mean that sound cannot travel through a vacuum
it needs a medium (skin, water, air, gel) to travel through.
Hz is a term that is interchangable with ..?
cycles
what does adjustable or non adjustable mean?
Whether the property can be adjusted within a given wave.
define a period in physics. What is it determined by and is it adjustable?
the measurement of time taken to complete one cycle. It is determined by the source and is not adjustable.
define wavelength in physics. What is it determined by and is it adjustable?
the measurement of the distance of one cycle. It is determined by both the source and the medium and it is not adjustable.
define frequency in physics. What is it determined by and is it adjustable?
the number of events that occur in a given amount of time. It is determined by the source and is not adjustable.
The Frequency is inversely related to which property?
The period and wavelength
What do the acoustic variables determine?
They distinguish between soundwaves and other waves
What are the acoustic parameters?
Period, frequency, wavelengeth, amplitude, power, intensity, velocity
What is interference?
When two sound waves occur at the same time in the same medium. They join to create one wave.
define amplitude in physics. What is it determined by and is it adjustable?
the difference between the maximum or minimum value and the average. It’s determined by source and is adjustable
What is Peak-to-Peak amplitude
Difference between the maximum and minimum
values
define power in physics. What is it determined by and is it adjustable?
the rate at which work is performed. It is determined by source and is adjustable.
define insensity in physics. What is it determined by and is it adjustable?
concentration of energy in a sound beam in Watts. It is determined by the source and adjustable.
How are intensity, power, and amplitude related?
They are directly related. Intensity and power are related to amplitude squared.
define propagation speed in physics. What is it determined by and is it adjustable?
rate at which a sound wave travels through a medium. it’s determined by medium and not adjustable
What is the average speed of sound in soft tissue
1540 m/s
How are frequency and wavelength related
they are inversely related.
What is attenuation? What determines it?
Attenuation is the weakening of the beam during a cycle. A high frequency and longer path will increase attenuation.
Between solid, liquid, and gas, which does sound travel fastest? slowest?
Fastest in solid, slowest in gas
what happens to the speed when you increase frequency?
notthing.
Are wavelength and velocity related?
No
If the sonographer has increased the amplitude of a wave by a factor of 4, what happens to power
it increases by 16
What is the equation for wavelength?
divide 1.54 mm by the frequency
Out of a group of period lengths, which would have the lowest frequency?
The longest period of time.
