Chapter 1

Question 1

the strongest reflection occurs when the beam strikes an interface at?

Answer 1

90 degrees

Question 2

the amount of time it takes US to travel 1 centimeter into tissue and 1cm back to the transducer

Answer 2

13 microsecond rule

Question 3

the average speed of the US through soft tissue

Answer 3

1540 m/sec

Question 4

the difference between the wave frequency directed into the tissues and what returns.

Answer 4

doppler shift

Question 5

the doppler angle of insonation for vascular application

Answer 5

60 degrees or less

Question 6

-two piezoelectric crystals
-has no range or depth resolution
-does not alia

Answer 6

continuous wave doppler

Question 7

two types of continuous wave doppler

Answer 7

analog
digital

Question 8

uses a zero-crossing frequency detector

Answer 8

analog

Question 9

what two ways can you solve for the doppler shift equation

Answer 9

-solve for frequency
-solve for velocity

Question 10

what are the two techniques employed for doppler analysis of blood flow?

Answer 10

-continuous wave
-pulsed wave

Question 11

what type of testing is continuous wave used for?

Answer 11

-non-imaging
-physiologic testing

Question 12

continuous wave doppler

Answer 12

-two piezoelectric crystals
-has no range or depth resolution (signals obtained from anywhere along the line of sight are displayed)
-does not alias

Question 13

counts the number of times the input signal crosses through zero (the baseline) within a given period of time, estimates and displays the frequencies present in the reflected wave

Answer 13

zero-crossing frequency detector

Question 14

drawbacks of analog doppler

Answer 14

-noise
-decreased sensitivity

Question 15

analyzes and displays all the frequencies moving through the sample area

Answer 15

fast fourier transfer

Question 16

what are the pros of digital (spectral analysis)

Answer 16

-more accurate
-better sensitivity
-less noise

Question 17

a single pulse of US is directed into the tissues, and the instrument waits for it to return before sending another pulse

Answer 17

pulse-listen cycle

Question 18

does pulsed doppler have range and depth resolution

Answer 18

yes

Question 19

the number of pulses per unit of time sent into the tissue

Answer 19

pulse repetition frequency

Question 20

small footprint, triangular US beam shape, resolution decreases in far field as scan lines diverge, not able to beam steer, typical frequency 1-5 MHz

Answer 20

sector transducer

Question 21

primary transducer for vascular application, large footprint, rectangular US beam, can beam steer, 5-10 MHz

Answer 21

linear transducer

Question 22

large footprint, trapezoidal US beam shape, resolution decreases in far field, not able to beam steer, typical frequency 2-5 MHz

Answer 22

curvilinear transducer

Question 23

number of cycles or vibrations per second

Answer 23

frequency

Question 24

what is the typical diagnostic ultrasound range in frequency

Answer 24

2MHz to 15 MHz

Question 25

what is the sample size for most arterial applications?

Answer 25

1.5 -2.5 mm

Question 26

the longer the pulse listen cycle, frame rate

Answer 26

decreases

Question 27

as depth increases, frame rate?

Answer 27

decreases

Question 28

ways to fix aliasing

Answer 28

-increase the scale (PRF) -adjust the baseline -obtain the data at a greater angle of incidence -change angle/window. bring vessel of interest closer to the surface -use lower frequency transducer -use continuous doppler