Ch 1. Fundamentals of Diagnostic Ultrasound

Question 1

What is the assumed average velocity of diagnostic ultrasound?

Answer 1

1540m/sec

Question 2

The distance between a band of compression or rarefaction is the sounds what?

Answer 2

Wavelength

Question 3

The number of times a wavelength is repeated per second is what?

Answer 3

Frequency

Question 4

What is the average velocity of sound traveling through fatty tissue?

Answer 4

1450 m/s

Question 5

What is the average velocity of sound traveling through gas?

Answer 5

331 m/s

Question 6

What is the average velocity of sound traveling through bone?

Answer 6

4080 m/s

Question 7

Higher frequency probes will affect wavelength how?

Answer 7

Higher frequency shortens the wavelength

Question 8

The product of a tissue’s density and sound velocity within the tissue is known as what?

Answer 8

Acoustic impedance

Question 9

Acoustic impedance is equal to what times what (formula)

Answer 9

Acoustic impedance (Z) = velocity (v) x tissue density (p)

Question 10

For the following frequencies what are their respective wavelength values?
2.0
3.0
5.0
7.5
10

Answer 10

Frequency (MHz) Wavelength (mm)
2.0 0.77
3.0 0.51
5.0 0.31
7.5 0.21
10 0.15

Question 11

Pulse length, frequency of the transducer that determines the ability to separate points along the axis. This is termed what?

Answer 11

Axial resolution

Question 12

Pulse repetition frequencies (PRF’s) of less than what (range) is needed for diagnostic ultrasound?

Answer 12

1 kHz - 10kHz

Question 13

Calculate the Interface distance when velocity = 1540 m/s (1.54 microsec), and round-trip time (RT) is 65microsec.

Answer 13

Interface distance = V (1.54 micro/s) x RT (65 micro/sec) / 2
50 mm.

Question 14

Time gain compensation controls are used to produce an image that is balanced in brightness from near to far field

Answer 14

YAY A GIMME!

Question 15

A-mode ultrasound is great for figuring out what value?

Answer 15

Amplitude, great for ophthalmic examinations

Question 16

This refers to the ability to resolve adjacent points perpendicular to the ultrasound beam axis along the scan plane

Answer 16

Lateral resolution

Question 17

Harmonic mode imaging may be particularly useful for scanning what organ?

Answer 17

Urinary bladder

Question 18

Spatial compounding in short does what?

Answer 18

Increases image quality by reducing the effect of speckle. Improves image contrast.

Question 19

An ultrasound artifact produced when minor beams travel off axis to the primary beam and interact with a reflective surface

Answer 19

Secondary lobe artifact or side lobe artifact

Question 20

Which artifact is produced when a portion of the beam is inside and outside an anechoic structure and can often appear as pseudo sludge in the urinary or gall bladder?

Answer 20

Slice thickness artifact

Question 21

An artifact produced when the ultrasound beam repeatedly bounces between two highly reflective surfaces or between the transducer and a strong reflector (gas or metal)?

Answer 21

Reverberation artifact

Question 22

The diffuse echoes between reverberation are known as what artifact?

Answer 22

Ring down artifacts

Question 23

What artifact is often seen when there is a large difference between acoustic impedances? Often seen with metal, foreign objects or a needle (aspiration)

Answer 23

Comet-tail artifact

Question 24

An artifact when the ultrasound beam encounters reflective surfaces and the echoes are interpreted in a straight line , often encountered at the lung/diaphragm interface

Answer 24

Mirror Image Artifact

Question 25

An artifact produced when the sound wave goes through tissues of different impedances and the sound wave changes directions, often causing organ duplication

Answer 25

Refraction artifact

Question 26

Artifact when two tissues in the near field to an organ have different propagation velocities and causes irregular borders to that organ.

Answer 26

Speed propagation artifact.

Question 27

Artifact when the ultrasound beam is entirely reflected or absorbed from either bone or metal.

Answer 27

Acoustic shadowing

Question 28

The shift in sound frequency as sound waves are reflected from moving targets, usually blood cells?

Answer 28

Doppler effect

Question 29

If motion is toward the transducer, the frequency of returning echoes is higher than that of the transmitted sound. This is what kind of shift?

Answer 29

Positive shift

Question 30

If the motion is away from the transducer, the frequency of returning echoes is lower than the transmitted sound. This is what kind of shift?

Answer 30

Negative shift