Put these metric prefixes in order from largest to smallest:

nano, mega, centi, milli, kilo, micro

*know how to convert these also*

mega - 10⁶ - million  (M)

kilo - 10³ - thousand  (k)

centi - 10^-2 - hundredth  (c)

milli - 10^-3 - thousandth  (m)

micro - 10-6 - millionth  (µ)

nano - 10^-9 - billionth  (n)

pressure

density

distance

Define Pressure.

Units?

concentration of force in an area

units: pascals (Pa)

Define density.

Units?

concentration of mass in a volume.

units: kg/cm³

Define distance.

Units?

Measure of particle motion.

Units: cm, mm, feet, etc.

Period

Frequency

Amplitude

Power

Intensity

Wavelength

Propagation speed

Both constructive and destructive interference occur

*see Fig. 2.7 pg. 15*

Define period.

Units?

The time from the start of one cycle to the start of the next cycle.

Units: seconds (s), milliseconds (ms), hours, other units of time.

Define frequency.

Units?

The number of cycles that occur in one second.

Units: hertz (Hz) "per second"

inversely

*as frequency increases, period decreases

*as frequency decreases, period increases

-also they are reciprocals of each other

period x frequency = 1

amplitude

power

intensity

Define amplitude.

Units?

The difference between the maximum value and the average value of a wave.

Units:decibels (dB)

sound source (txr) initially....then medium because it

decrease as it propagates through the body

the difference between maximum and minimum values of an acoustic variable.

*twice the value of amplitude

Define power.

units?

the rate of energy transfer or the rate at which work is performed.

Units: watts

When power increases, so does amplitude.

When power decreases, so does amplitude.

power ∞ amplitude²

*(∞ = proportional, I couldn't find the real sign on here)

Power is increase by 9

*power ∞ amplitude², therefore 3x3=9*

Power is decrease by 1/4 or 25% of its original value.

*power ∞ amplitude², therefore 1/2 x 1/2 = 1/4*

Define intensity.

Units?

The concentration of energy in a sound beam.

Units: W/cm²

Intensity (W/cm²) = power(w) / area (cm²)

intensity is propertional to power

(intensity ∞ power)

*if a waves power is doubled, intensity is doubled

intensity ∞ amplitude²

*if a waves amplitud is doubled, the intensity is increased 4 times its original value

Define Wavelength.

Units?

The distance or length of one complete cycle.

Units: mm, meters

sound source AND medium

*only parameter determined by both*

Inversely

*as frequency increases, wavelength decreases

*the lower the frequency the shorter the wavelength

Define propagation speed.

Units?

The distance that a sound wave travels through a medium in 1 second.

Units: mm/µs

Put these in order of speed from slowest to fastest.

lung, soft tissue, bone, fat, air

Stiffness and Speed are directly related, if one goes up so does the other.

Density and Speed are inversely related, if one goes up the other goes down

elasticity or compressability

**note: these are opposite of stiff, they mean non-stiff

**bulk modulus means stiff

pulse duration

pulse repitition period

pulse repitition frequency

duty factor

spatial pulse length

transmit, talking, or "on" time

receive, listening, or "off" time

Define pulse duration.

Units?

The actual time from the start of a pulse to the end of that pulse. (only the "on" time)

Units: time (seconds, ms, μs)

many cycles in the pulse, or

individual cycles with long periods

few cycles in the pulse, or

individual cycles with short periods

Define spatial pulse length.

Units?

the distance that a pulse occupies in space from the start to the end

Units: mm, m, other units of distance

Define pulse repitition period.

Units?

the time from the start of one pulse to the start of the next pulse. (includes one "on" time and one "off" time)

units of time: seconds, ms

adjust the depth of view

**shallow depths, short pulse repitition period

**deep depths, longer prp

directly.

**as depth increases, prp increases (listening time and talking time lengthen)

**as depth decrease, prp decreases (listening time and talking time shorten)

(see pg. 53 for images)

Define pulse repitition frequency.

Units?

the number of pulse that an ultrasound system transmits into the body each second.

Units: Hz

inversely

*as depth increases, PRF decreases

*as depth decreases, PRF increases

inversely

*also they are reciprocals

PRF x PRP = 1

Which of these four values for pulse repetition frequency would have the longest pulse repition period?

A. 2 kHz

B. 4,000 Hz

C. 6 Hz

D. 1 kHz

Define Duty factor.

units?

the percentage or fraction of time that the system is transmitting a pulse.

Units: NONE (percentage)

.1 - 1% (.001 - .01)

*very little talking, lots of listening

inversely

*duty factor is higher when imaging at shallow depths

1, or 100%

This value is only achieved with continuous wave sound

0%

Exists only when the transducer is silent (machine turned off)

Shallow imaging creates _____ listening time, ________PRP, _______ PRF, and _______ duty factor.

less listening time

shorter PRP

higher PRF

higher duty factor

more listening

longer PRP

lower PRF

lower duty factor

Spatial (refers to distance or space)

Peak (the max value)

Average

Temporal (all time, transmit and recieve)

Pulsed (only the transmit time)

All intensities have units of ________.

* #4 of the "Ten Commandments" of Intensity pg. 72*

Rank these intensities from largest to smallest:

SPTP, SATP, SPTA, SATA, SPPA, SAPA

SPTP > SPPA > SPTA> SATP > SAPA > SATA

hints:

*spatial peaks come before averages

*I'd rather be a PA than a TA, and you have to have TP!

6

*count the zeros*

Decibels are a ______.

The ________ level is divided by the ________ level.

ratio.

actual / starting

When a wave's intensity doubles, the relative change is 3 dB.

*3 dB = 2 times bigger

*6 dB = 4 times bigger

*9 dB = 6 times bigger

10 dB

*10 dB = 10 times bigger

*20 dB = 100 times bigger

*30 dB = 1000 times bigger

-3 dB

*-3 dB = 1/2 of original strength

*-6 dB = 1/4 of original strength

*-9 dB = 1/6 of original strength

-10 dB

*-10 dB = 1/10 of original strength

*-20 dB = 1/100 of original strength

*-30 dB = 1/1000 of original strength

reflection

scattering

absorption

sound energy hits something and some of the sound comes back

Put these attenuators in order from the biggest attenuator to the smallest:

water, bone, soft tissue, air, lung

air

bone

lung

soft tissue

water

What does not go back to the transducer?

A. scattering

B. absorption

C. reflection

Diffuse Reflection

"backscatter"

"non-specular"

sound returning back to the transducer in a disorganized fashion due to rough boundaries

*only a portion returns to the txr

the sound energy is diverted in all directions in an organized fashion

*some sound energy returns to txr

total attenuation (dB)=

attenuation coeff (dB/cm) x distance (cm)

1/2

atten. coeff. (db/cm) = frequency (MHz)/ 2

0.5 dB/cm

MHz

total attenuation = 20 dB

*you must find attenuation coefficient first, then x distance

impendence (rayles) (z) =

density (kg/m³) x speed (m/s)

the acoustic resistance to sound traveling in a medium

*We depend on the differences in impedences to produce a pictue.

1,250,000 - 1,750,000 rayls

or

1.25 - 1.75 Mrayls

perpendicular

orthogonal

right angle

ninety degress

normal

*PORNN

Acute - less than 90 degrees

Right - exactly 90 degrees

Obtuse - greater than 90 degrees

A sound wave with intensity of 50 W/cm² strikes a boundary and is totally reflected. What is the intensity relection coefficient?

A. 50 W/cm²

B. 25 W/cm²

C. 0 W/cm²

D. 100%

E. 0

D. 100%

*IRC is the intensity that bounces back when a beam strikes the boundary between 2 media

A sound wave with intensity of 50 W/cm² strikes a boundary and is totally reflected. What is the reflected intensity?

A. 50 W/cm²

B. 25 W/cm²

C. 0 W/cm²

D. 100%

E. 0

100%

*conservation of energy at a boundary

IRC = intensity bounced back

ITC = intensity transmitted

1%

* 99% or more of incident energy is transmitted

99%

Which of the following terms do not belong with the others?

A. orthogonal

B. oblique

C. normal

D. perpendicular

B. Oblique

*remember PORNN

different

*high impedence = high reflection

similar impedence = little reflection

no impedence = no reflection

When a beam strikes a boundary obliquely, reflection may or may not occur.

If it does occur, reflection angle will ______ the incident angle.

sin (transmission angle) = speed of medium 2

sin(incident angle)           speed of medium 1

*transmission angle > incident angle when

speed of medium 2 > speed of medium 1

(bends downward)

*transmission angle < incident angle when

speed of medium 2 < speed of medium 1

(bends upward)

oblique angle

different propagation speeds

30 degrees

*angle of reflection = angle of incidence, everything else is distractors!

directly

*increase distance = increase time of flight (increased by a factor of 2)

*decrease distance = decrease time of flight

13, 1cm

*total distance traveled = 2cm

A sound wave is created by a transducer, reflects off an object, and returns to the transducer. The depth of the reflector is 10 cm in soft tissue. What is the go-return time?

A. 13 μs

B. 1.3 μs

C. 65 μs

D. 130 μs

D. 130 μs

*time of flight = depth x 13 μs

Lead zirconate titanate (PZT)

barium titanate

lead titanate

lead metaniobate

approx. 360 degrees

* if crystal is heated above this point, it will lose piezoelectric properties and be "depolarized" FOREVER

use sterile probe cover

refers to the application of a chemical agent to reduce or eliminate infectious organisms on the txr.

*our txrs are disinfected using t-spray or cidex

Know image of basic transducer construction. Pg 118

including: case, wire, matching layer, backing material

the impedence of the PZT is about 20 times greater than the impedence of the skin so the intensity would be reflected back instead of enter the body.

matching layer decreases reflections at the skin's boundary

Put these in decreasing order of impedence:

matching layer, PZT, skin, gel

Shortens SPL, pulse duration (limits ringing)

increases picture accuracy

improves axial resolution (LARRD)

decreased sensitivity

wide bandwidth

low "Q" factor

the range, or difference, between the highest and the lowest frequencies in the pulse.

bandwidth (Hz) = max. frequency - min frequency

backing material

*they are high-Q and narrow bandwidth

inversely

*wide bandwidth = low Q-factor

equals

*electrical frequency = acoustic frequency

1. speed of sound in the PZT

2. thickness of the PZT

*high speed = high frequency

*thich crystal = low frequency

(think of thick guitar string = low tone)

The impedence of a transducer active element is 1,900,0000 Rayls, and the impedence of the skin is 1,400,000 Rayls. What is an acceptable impedence for the matching layer?

A. 1,200,000 Rayls

B. 1,400,000 Rayls

C. 1,726,000 Rayls

D. 1,950,000 Rayls

The near zone is the ________ from the transducer to the focus.

Also called?

region

also called: Fresnel zone, near field

txr diameter

frequency of sound wave

*bigger diameter = deeper focus

*higher frequency = deeper focus (neglecting attenuation)

transducer diameter

frequency of sound

*larger diameter = less divergence in far field

*higher frequency = less divergence in far field

One large PZT is made up of teeny, tiny, multiple crystals

Each tiny crystal produces a diffraction (v-shaped) pattern

Hourglass shaped beam results from interference of waves

LARRD Resolution

L- longitudinal

A- axial

R- range

R- radial

D- depth

Great axial resolution is associated with

______ spatial pulse length

______ pulse duration

______ frequencies

_________ wavelength

________ cycles

_______ ringing

_________ numerical value

shorter spatial pulse length

shorter pulse duration

high frequency

short wavelength

few cycles

less ringing

 lower numerical value

Which of the following transducers has the poorest axial resolution?

A. 1.7 MHz and 4 cycles/pulse

B. 2.6 MHz and 3 cycles/pulse

C. 1.7 MHz and 5 cycles/pulse

D. 2.6 MHz and 2 cycles/pulse

Which of the following has the best axial resolution?

A. 1.7 MHz and 4 cycles/pulse

B. 2.6 MHz and 3 cycles/pulse

C. 1.7 MHz and 5 cycles/pulse

D. 2.6 MHz and 2 cycles/pulse

LATA

Lateral

Angular

Transverse

Azimuthal

1. external focusing - lens

2. internal focusing - with a curved active element

3. phased array focusing - with the electronics of the system

No.

*also called fixed focusing (aka mechanical coventional)

-a narrow "waist" in the beam

- focal depth is shallower

- beam diameter in the far zone increases

-focal zone is smaller

-improves lateral resolution

4.5 mm

*at the end of the near zone, the beam diameter is 1/2 the transducer diameter.

9mm

*at a depth of twice the near zone, the beam is as wide as the transducer

Increases.

*with more cycles in a pulse, the pulse becomes longer. the numerical value of the range resolution increases

Degrades.

*When the number of cycles increases, the spatial pulse length increases and the image quality degrades

Which of the following transducers has the best lateral resolution deep in the far field?

A. 4 MHz, 4 mm crystal diameter

B. 6 MHz, 4 mm crystal diameter

C. 4 MHz, 6 mm crystal diameter

D. 6 MHz, 6 mm crystal diameter

1. What are the 3 basic modes of display, or formats, are important in viewing ultrasound information?

Amplitude mode

Brightness mode

Motion mode