review: Test4

Question 1

axial resolution deals with structures that are _____ to the sound beam.

Answer 1

parallel

Question 2

if frequency increases, what do we do to the numerical value of LARRD?

Answer 2

the numerical value is lowered

Question 3

given frequency and cycles/pulse, which one has the better axial resolution?

Answer 3

the shortest pulse with the highest frequency and the least ringing (fewest cycles/pulse)

Question 4

given cycles and frequencies, calculate axial resolution

Answer 4

axial resolution is 1/2 the spatial pulse length

axial resolution is 1/2 (wavelength x #cycles/pulse)

Question 5

if the frequency is the same, know which characteristics will distinguish the better axial resolution

Answer 5

the shorter cycle pulse transducer will create better axial resolution

Question 6

what are the different synonyms for LARRD?

Answer 6

longitudinal

axial

range

radial

depth

Question 7

what are the synonyms for LATA?

Answer 7

lateral

angular

transverse

azimuthal

Question 8

how do we calculate lateral resolution?

Answer 8

determined by width of the sound beam

lateral resolution=beam diameter(mm)

Question 9

what are the methods of focusing?

Answer 9

external focusing-with a lens (fixed, conventional, or mechanical)

internal focusing-with a curved active element (fixed, conventional, or mechanical)

phased array focusing-with the electronics of the ultrasound system (adjustable)

Question 10

what are the effects of focusing?

Answer 10

beam diameter in near field and focal zone is reduced

focal depth is shallower

beam diameter in the far zone increases

focal zone is smaller

Question 11

better axial resolution is associated with:

Answer 11

shorter spatial pulse length

shorter pulse duration

higher frequencies (shorter wavelength)

fewer cycles/pulse (less ringing)

lower numerical values

Question 12

summary of beam features:

characteristics: frequency-continuous wave

Answer 12

determined by: frequency of electrical signal from ultrasound system

Question 13

summary of beam features:

characteristics: frequency-pulsed wave

Answer 13

determined by: thickness of ceramic and speed of sound in ceramic

Question 14

summary of beam features:

characteristics: focal length

Answer 14

determined by: diameter of ceramic and frequency of sound

Question 15

summary of beam features:

chaacteristics: beam divergence

Answer 15

determined by: diameter of ceramic and frequency of sound

Question 16

summary of beam features:

characteristics: lateral resolution

Answer 16

determined by: beam width

Question 17

axial resolution(frequency):

orientation, mnemonic, determined by, best with, does it change?, in near field-best with, in far field-best with

Answer 17

front-to-back, parallel to beam

LARRD

pulse length

shortest pulse, highest frequency and fewest cycles

same at all depths, does not change

shortest pulse

shortest pulse

Question 18

lateral resolution(focus):

orientation, mnemonic, determined by, best with, does it change?, in near field-best with, in far field-best with

Answer 18

side-by-side, perpendicular to beam

LATA

beam width

narrowest beam

changes with depth, best at focus

smallest diameter crystal

largest diameter and highest frequency (least divergence)