Physics Final Fall 2011

Front 1

sound waves are_____

Back 1

longitudinal
mechanical

Front 2

The speed of US in soft tissue is closest to_____

Back 2

1500 m/s

Front 3

The frequency closest to the lower limit of US is _____

Back 3

15,000Hz

Front 4

____ is the time to complete one cycle.

Back 4

PERIOD

Front 5

What is the FQ of a wave with 1 msec period?

Back 5

1kHz

Front 6

Which of the following is determined by the source and the medium?

Back 6

RANGE RESOLUTION

Front 7

Propagation speed=_______ X wavelength

Back 7

FQ

Front 8

As a result of ____ the propagation speed increases.

Back 8

DECREASING COMPRESSIBILITY AND DECREASING DENSITY

Front 9

Put in decreaseing order of propagation speed

Back 9

Solid
Liquid
Gas

Front 10

If the FQ of US is increased from 0.77 MHz to 1.54 MHz, what happens to the wavelength?

Back 10

HALVED

Front 11

A sound waves's FQ is 10 MHz. The wave is traveling in soft tissue. What is its wavelength?

Back 11

0.15 mm

Front 12

If the FQ of an US wave is doubled, what happens to the period?

Back 12

Halved

Front 13

The units of PRF are?

Back 13

msec

Front 14

The time from the beginning of a pulse until its end is?

Back 14

PULSE DURATION

Front 15

What happens to the speed of sound in a medium when the bulk modulus of the medium increases?

Back 15

FASTER

Front 16

If a wave's amplitude is doubled, what happens to the power?

Back 16

QUADRUPLED

Front 17

Power of sound has units of?

Back 17

WATTS

Front 18

If the intensity of a sound beam remains unchanged while the beam area is reduced in half, what has happened to the power?

Back 18

HALVED

Front 19

Which of these intensities are smallest

Back 19

SATA

Front 20

The duty factor for continuous wave ultrasound is?

Back 20

1.0

Front 21

What are the units of intensity?

Back 21

WATTS/CM SQUARED

Front 22

Sound intensity is decreased by 75%. How many DB of attenuation is this?

Back 22

6dB

Front 23

The fundamental FQ of a transducer is 2.5MHz. What is the second harmonic FQ?

Back 23

5 MHz

Front 24

A pulse is emitted by a transducer and is traveling in soft tissue. The go-return time, or time-of flight, of a sound pulse is 130 microseconds. What is the reflector depth?

Back 24

10 cm

Front 25

If a 5MHz sound wave is traveling in the tissues listed below, which will have the longest wavelength?

Back 25

BONE

Front 26

What is the approximate attenuation coefficient of 1 MHz US in soft tissue?

Back 26

0.5 dB/cm

Front 27

The rayl is the unit of?

Back 27

IMPEDANCE

Front 28

What are attenuation's three components?

Back 28

SCATTERING
REFLECTION
ABSORPTION

Front 29

The angle b/w an US pulse and the boundary b/w 2 media is 90 degrees, what is this called?

Back 29

ORTHOGONAL INCIDENCE

Front 30

Refraction only occurs if there are?

Back 30

OBLIQUE INCIDENCE AND DIFFERENT PROPAGATION SPEEDS

Front 31

Which of the following tissues is most likely to create Rayleigh scattering?

Back 31

RED BLOOD CELLS

Front 32

With normal incidence the angle is 180 degrees

Back 32

FALSE

Front 33

Snells law describes physics of ______

Back 33

REFRACTION

Front 34

The most likely amount of reflection at a boundary b/w soft tissue is?

Back 34

1%

Front 35

Doppler shifts always occur if the sound source and receiver are in motion

Back 35

FALSE

Front 36

The doppler shift is a measure of?

Back 36

DIFFERENCE B/W INCIDENT & REFLECTED FQ

Front 37

There have not been biological effects from US found in a laboratory.

Back 37

FALSE

Front 38

In an analog scan converter what component stores the image data?

Back 38

DIELECTIC MATRIX

Front 39

What increases patient exposure?

Back 39

EXAM TIME

Front 40

Shadowing may result from high amounts of refelection of US energy

Back 40

TRUE

Front 41

Where are harmonics created?

Back 41

IN THE TISSUES

Front 42

Which transducer would be best to image superficial structures?

Back 42

SMALL DIAMETER, HIGH FQ

Front 43

A transducer with more than one active element is called?

Back 43

ARRAY

Front 44

How many bits are needed to represent 16 shades of gray?

Back 44

4

Front 45

What information does doppler shift provide?

Back 45

VELOCITY

Front 46

A sound wave is a pressure wave made of compressions and rarefactions.

Back 46

TRUE

Front 47

A hydrophone is used to measure?

Back 47

FQ
INTENSITY

Front 48

Images on videotape are stored using?

Back 48

MAGNETISM

Front 49

Circumferences may be measured in unit of?

Back 49

CM

Front 50

Decimal uses a base of 10, binary uses a base of?

Back 50

2

Front 51

If the frame rate increases and the lines per frame is unchanged, what else must happen?

Back 51

DEPTH DECREASES

Front 52

Which of the following is not a beam steering technique for a mechanical scanhead?

Back 52

PHASED BEAM

Front 53

Which has the greatest amount of attenuation?

Back 53

BONE

Front 54

Which of the following will result in the greatest number of shades of gray in a digital image display?

Back 54

LARGE PIXELS W/MANY BITS/PIXEL

Front 55

With good images on the display but not on the printer, one should?

Back 55

ADJUST THE RECORDER

Front 56

To measure the US beam intensity, use a?

Back 56

CALIBRATED HYDROPHONE

Front 57

When the US machine displays only strong reflecting objects and nothing else, the sonographer should?

Back 57

INCREASE OUTPUT POWER

Front 58

Compression is used to?

Back 58

DECREASE THE RANGE OF AMPLITUDES

Front 59

Reject is used to?

Back 59

Adjust the appearance of lowly reflective objects

Front 60

If a refletor is moved twice as far away from the transducer, how will this affect the time-of-flight of a sound pulse?

Back 60

DOUBLE IT

Front 61

In which of these biologic tissues will sound waved propagate most quickly?

Back 61

TENDON

Front 62

While scanning in a water tank, what location in a sound beam has the highest intensity?

Back 62

FOCAL POINT

Front 63

Which of the following improves the signal-to-noise ratio?

Back 63

FRAME AVERAGING

Front 64

What is the standard for communication b/w medical imaging computers?

Back 64

DICOM

Front 65

In a B-mode display, which of the following axes are used for the amplitude of the reflection?

Back 65

Z-AXIS

Front 66

The dynamic range is the ratio of the smallest to the largest ____ that a system can process w/o distortion.

Back 66

AMPLITUDE

Front 67

When may a patient revoke their consent to be treated?

Back 67

AT ANY TIME

Front 68

If the intensity is increased by 3dB, it?

Back 68

DOUBLES

Front 69

What determines the FQ of a sound beam from a pulsed transducer?

Back 69

PZT THICKNESS

Front 70

What measures the output of a transducer?

Back 70

HYDROPHONE

Front 71

Which type of artifact appears most commonly with highly reflective objects?

Back 71

SHADOWING

Front 72

What is the fraction of time that a transducer is transmitting?

Back 72

DUTY FACTOR

Front 73

The dB is defined as the ____ of 2 intensities

Back 73

RATIO

Front 74

If the power of a sound wave is increased by a factor of 8, how many decibels is this?

Back 74

9dB

Front 75

An ultrasound system is set at 0 dB and is transmitting at full intensity. What is the output power when the system is transmitting at 50% of full intensity?

Back 75

-3 dB

Front 76

The doppler shift is the ____ of 2 frequencies.

Back 76

DIFFERENCE

Front 77

What may be a unit of amplitude?

Back 77

CM

Front 78

In an air-tissue interface, what percentage of the US is reflected?

Back 78

near 100%

Front 79

How many bits are needed to represent 1024 gray shades?

Back 79

10

Front 80

What is the production of deformation from voltage called?

Back 80

PIEZOELECTRICITY

Front 81

Which is not a part of a transducer?

Back 81

A/D CONVERTER

Front 82

Rectification and smoothing are components of which of the following?

Back 82

DEMODULATION

Front 83

The propagation speed of US in the AIUM test object is?

Back 83

1.54 mm/us

Front 84

the fresnel is the

Back 84

NEAR ZONE

Front 85

Which of these boundaries will create the strongest reflection?

Back 85

air-soft tissue