Physics Chapters 5-6 Santanna

Question 1

Intensity may be reported in various ways with respect to

Answer 1

space and time

Question 2

_____ is a key parameter with regard to bio effects

Answer 2

Intensity

Question 3

_____ is being the most relevant to tissue heating

Answer 3

SPTA ( spatial peak temporal average)

Question 4

_____ is greater than average

Answer 4

peak

Question 5

What is the highest intensity?

Answer 5

SPTP (spatial peak temporal peak)

Question 6

What is the lowest intensity?

Answer 6

SATA (spatial average temporal average)

Question 7

positive decibels means intensity is getting

Answer 7

bigger

Question 8

negative decibels means intensity is getting

Answer 8

smaller

Question 9

What is the decrease in strength of a sound wave as it travels? What is the units?

Answer 9

attenuation, dB

Question 10

True or false? The further sound travels, the weaker it gets or the move it attenuates

Answer 10

True

Question 11

In soft tissue, ___ frequencies attenuate less.

Answer 11

lower

Question 12

This is reflection from a smooth reflector, like a mirror. It returns in one direction.

Answer 12

specular reflection

Question 13

What happens when propagating sound energy strikes a boundary between two media and some energy returns to the probe?

Answer 13

reflection

Question 14

The reflection of sound back in the general direction of the probe but in a number of directions

Answer 14

diffuse reflection or backscatter

Question 15

What is the distrubtion of sound randomly in all directions.

Answer 15

scattering

Question 16

Does higher frequency scatter more?

Answer 16

YES

Question 17

What is the equation for rayleigh scattering and the definition?

Answer 17

organized and omidirectional

rayleigh scattering is proptional to frequency^4

Question 18

what is the amount of attenuation per centimeter is called? What are the units?

Answer 18

attenuation coefficient and dB/cm

Question 19

attenuation coefficient is directly related to

Answer 19

frequency

Question 20

The distance sound travels in a tissue that REDUCES the intensity of sound to one-half of its original value
the units are

Answer 20

half value layer thickness

cm

Question 21

What does half value layer thickness depend upon?

Answer 21

the medium and frequency of sound

Question 22

Thin half value means

Answer 22

higher frequency sound media with high attenuation rate

Question 23

Thick half value means

Answer 23

low frequency sound media with low attenuation rate

Question 24

What is calculated not measure? A number associated with a medium

Answer 24

Impedance

Question 25

What is the units for impedance?

Answer 25

Rayls (Z)

Question 26

A normal incidence

Answer 26

perpendicular orthogonal right angle ninety degrees

Question 27

anything other than a 90 degree angle

Answer 27

oblique incidence

Question 28

Intensity of the sound wave prior to striking a boundary

Answer 28

incident intensity

Question 29

the intensity after striking the boundary that turns around and reflects back to the probe

Answer 29

reflected intensity

Question 30

the intensity that after striking the boundary continues on in the same direction

Answer 30

transmitted intensity

Question 31

The % of the US intensity that bounces back when the sound strikes a boundary

Answer 31

Intensity Reflection Coeficient (IRC)

Question 32

Is IRC and ITC unitless?

Answer 32

True

Question 33

% of incident intensity that after striking the boundary continues on in the same direction

Answer 33

Intensity Trasmission Coefficent

Question 34

What occurs if the two media at the boundary have different acoustic impendaces ?

Answer 34

reflection

Question 35

Will transmission and reflection with oblique incidence occur?

Answer 35

It may or may not

Question 36

Materials used for the matching layer of a transducer must have an impedance level between the

Answer 36

skin and PE element

Question 37

What is the function of the damping material of an ultrasound transducer

Answer 37

reduces "ringing" of the PZT

Question 38

A ____ MHz transducer will have the thinnest element a. 2 mhz b. 12 mhz c. 5 mhz

Answer 38

12

Question 39

A frequency of the transducer depends primarily on the

Answer 39

element thickness

Question 40

While scanning soft tissue, the reflected wave returned to the transducer in 5usec. How far away is the reflector?

Answer 40

4 cm

Question 41

Range equation is used to determine the

Answer 41

distance to the reflector

Question 42

damping of the sound beam

Answer 42

reduces the SPL

Question 43

What is defined as the range of frequencies contained in the US pulse.

Answer 43

bandwidth

Question 44

The use of backing material would result in all the following expect: a. wider bandwidth b. lower quality images c. decreased sensitivity d. lower Q factor

Answer 44

b

Question 45

if you change from a transducer with 20 mm crystal thickness to one with 40 mm thickness, the frequency of the sound produced will:

Answer 45

half

Question 46

imaging probes have a ___ q factor and a ____ bandwidth

Answer 46

low and wide

Question 47

as transducer frequency ____ the q factor ___

Answer 47

increases and increases they are directly related

Question 48

a larger bandwidth leads to

Answer 48

improved axial resolution

Question 49

as the q factor increases the bandwidth

Answer 49

decreases/ narrows

Question 50

What is time of flight?

Answer 50

time it takes for a pulse to travel to and from the transducer and the reflector

Question 51

the time of flight and the distance the sound travels are ____ related

Answer 51

directly

Question 52

what is a property of material to create a voltage when pressure is applied or when the material is mechanically deformed.

Answer 52

piezoelectric effect

Question 53

Man made peizoelectric materials

Answer 53

lead zirconate titanate (PZT) barium titanate lead titanate

Question 54

natural piezoelectric materials

Answer 54

quartz and tourmaline

Question 55

What degrees can PZT be destroyed at?

Answer 55

360` C 680` F this is why we can't autoclave probes

Question 56

what is the complete destruction of all living microorganisms by means of exposure to heat, chemicals, or radiation.

Answer 56

sterilization

Question 57

using a chemical agent to reduce or eliminate infectious organisms on probes

Answer 57

disinfection

Question 58

What is HLD?

Answer 58

higher level disinfecting (vaginal probes)

Question 59

Can we use alcohol as a disinfectant?

Answer 59

NO

Question 60

What transducer component protects the internal components from damage, and insulates the patient from electrical shock.

Answer 60

case

Question 61

What is active element?

Answer 61

piezoelectric crystal that is also called PZT, ceramic, or crystals.

Question 62

How thick is active element or PZT?

Answer 62

1/2 wavelength thick

Question 63

Backing element/ Damping element is made of

Answer 63

epoxy resin impregnated with metal powder

Question 64

When a emitted sound is dampened, what happens

Answer 64

it is short in duration and length

Question 65

crystal damping enhances

Answer 65

axial resolution

Question 66

where is the matching layer postioned

Answer 66

in front of the PZT at the face of the transducer

Question 67

how thick is the matching layer

Answer 67

one-quater wavelength thick

Question 68

does CW probes need backing/damping materials

Answer 68

NO

Question 69

Impedences

Answer 69

PZT > Matching layer> gel> skin

Question 70

what are imaging transducer characteristics

Answer 70

damping is effective short pulse length and duration low sensitivity wide bandwidth low q factor decreased output power

Question 71

no damping and narrow bandwidth

Answer 71

high q factor (CW)

Question 72

damping and wide bandwidth

Answer 72

low q factor

Question 73

characteristics of high frequency pw imaging transducers

Answer 73

thinner, PZT crystals PZT with higher speeds

Question 74

characteristics of low frequency pw imaging transducers

Answer 74

thicker PZT crystals PZT with lower speeds