Ultrasound Physics Flashcards
What is the definition of related or proportional?
Two items that are associated or affiliated. However, the relationship between the items does not have be specified.
What is the definition of inversely related or inversely proportional?
Two items are associated such that when one item increases, the other decreases.
What is a reciprocal relationship?
When two numbers with a reciprocal relationship are multiplied together, the result is one.
Are reciprocal numbers inverse?
Yes. Reciprocal numbers are inverse because when one increases, the other decreases.
What do all numerical values have to have?
A corresponding unit. Such as inches, feet, liters.
What are units of length?
Distance or circumference: centimeters, feet
What are units of area?
Centimeter squared, ft. Squared
What are units of volume?
Centimeters cubed or feet cubed
What does increase by a factor mean?
Increased by a factor means to multiply by that number.
What does increase by a factor of six mean?
Six times larger.
What does decrease by a factor mean?
Decrease by a factor means to divide by that number.
What does decrease by a factor of 3 mean?
One third
A number followed by the word ————– is unitless.
Percent
What is the complimentary metric unit for billions and billionths? What are the abbreviations? What are the powers?
Giga and nano, G and n, Giga = 10 to the ninth, nano = 10 to the -ninth
What is the metric unit names for millions and millionths? What are the abbreviations? What are the exponents?
Mega and micro, M and u, Mega = 10 to the sixth, micro = 10 to the -sixth
What are the metric prefixes for thousand and thousandths? What are the abbreviations? What are the exponents?
Kilo and milli, k and m,
kilo =10 to the third
milli =10 to the -third
What are the metric prefixes for hundreds and hundredths? What are the prefixes? What are the abbreviations?
hecto and centi, h and c
hecto = 10 to the second
centi = 10 to the -second
What is the metric prefixes for tens and tenths? What are the abbreviations? What are the exponents?
deca and deci, da and d
deca = 10 to the first
deci = 10 to the -first
What is the definition for directly related or directly proportional?
Two items that are associated such that when one item increases, the other increases.
Define period.
The time from the start of ONE cycle to the start of the next cycle.
What units is PERIOD reported in? Typical values?
Microseconds, units of time; 0.06 to 0.5 us (microseconds)
PERIOD is determined by ……..
Sound source only, not by the medium.
Is the PERIOD adjustable?
No
What is the relationship between frequency and period?
Inversely related, and reciprocal.
Define FREQUENCY.
Frequency is the number of cycles that occur in one second in ultrasound. Outside of ultrasound, it is the number of events per specific duration of time.
What type of units is frequency reported in? What are the typical values for FREQUENCY in ultrasound?
Hertz. 2MHz to 15MHz.
What is 1 hertz?
One cycle per one second = one hertz
What is another way to say 2 MHz to 15MHz?
2 million to 15 million per second
FREQUENCY is determined by the……
Sound source only.
Is FREQUENCY adjustable?
No
What is processed into images?
Reflections arising from boundaries between structures in the body.
What do all waves carry from one location to another?
Energy
Sound is a __________ wave in which particles in the medium move.
Mechanical
What does sound have to travel through?
A medium
What happens to the molecules when sound travels through a medium?
Molecules are alternately compressed and rarefied
Sound travels in a _______ line and sound waves are __________(direction) waves.
Straight; longitudinal
Define acoustic propagation properties.
The effects of the medium on the sound wave.
Define biological effects.
The effects of the sound wave upon the biological tissue through which it passes.
The effects of the medium on the sound wave is termed……
Acoustic propagation properties
The effects of the sound wave upon the biologic tissue through which it passes is called……
Biologic effects
How are sound waves identified?
By oscillations in acoustic variables.
What are the three acoustic variables that are used to distinguish between sound waves and other types of waves?
Pressure, density and distance
Define pressure.
Concentration of force in an area.
What are the units for PRESSURE?
Pascals, Pa
Define density.
Concentration of mass in a volume.
What are the units for DENSITY?
kg/cm3
Define DISTANCE.
Measure of particle motion.
How do you tell if a wave is a sound wave?
If one of the acoustic variables has a rhythmic oscillation.
What is another term for sound waves?
Acoustic waves
What are the seven acoustic parameters that are used to describe the characteristics of a sound wave?
Period, frequency, amplitude, power, intensity, wavelength, propagation speed
What occurs in a transverse wave?
Particles move in a direction that is perpendicular to the direction that the wave propagates.
How do particles move in a longitudinal wave?
Particles move in the same direction that the wave propagates.
When are waves considered “in-phase”?
When their peaks occur at the same time and at the same location. Also their troughs.
When two waves peaks (and troughs) occur at different times the waves are said to be…..
Out of phase
What is the combination of two waves that lose their individual characteristics and combine to form a single wave called? What is this combining of waves a result from?
Interference; multiple sound beams arriving at an identical location at the same time
What are the two different ways the interference of waves can be described as?
Constructive interference, destructive interference
The interference of a pair of “in-phase” waves is called……
Constructive interference
The interference of a pair of “out-of-phase” waves us called….
Destructive interference
The interference of “in-phase” waves results in the formation of….
A single wave of greater amplitude than either of its components.
The interference of a pair of “out-of-phase” waves results in the formation of…..
A single wave of lesser amplitude than at least one of its components.
What happens when two out-of-phase waves are of equal amplitude?
Complete destructive interference may occur. The waves are cancelled out.
What happens when waves of different frequencies interfere?
Both constructive and destructive interference occurs
What describes the features of a sound wave?
Parameters
What is the SOURCE of a sound wave?
The ultrasound system and the transducer
Another name for tissue is called…..
Medium
