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yo yo oyo
39
Accounting
Post-Graduate
05/24/2012

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Term
what is another name for Fresnel Zone?
Definition
Near Zone
Term
in ultrasound imaging, what is the most common piezoelectric material used?
Definition
Lead zirconate Titanate or PZT
Term
what are the results when damping materials is added to thge transducer?
Definition
reduce ringing of the pulse
-decreases SPL, PD
-increases wide bandwidth
-improves axial resolution
Term
which materials are naturally piezoelectric?
Definition
quartz amber
tourmaline glucose
rochell
Term
what will happen to the near zone length if the transducer's frequency is changed from 5.0 MHz to 10.0 MHz
Definition
"it doubles"
Term
which type of transducer are grating lobes associated with?
Definition
phased arrays transducer
Term
what is electronic curvature?
Definition
"firing patterns that focus beam"
Term
should the sonographer use high or lower frequency transducer to obtain improved spatial resolution?
Definition
higher
Term
what is the name of the transducer which has collection of ringed elements with a common center?
Definition
Annular Phased Arrays
Term
True or False : many active elements are fired almost at the same time with Phased Arrray Transducer?
Definition
TRUE
Term
what is the name of the principle which states thaT each tiny part of the transducer face may be considered a separate and individual sound source?
Definition
Hygens Principle
Term
what would be the most acceptable choice for the matching layer when the impedance of the transducer's piezoelectric element is 1,800,000 rayls and the impedance of the skin is 1,4000,000 Rayls?
Definition
pzt > matching layer > gel > skin

find a number in between
Term
what is th eterm used when the firing pattern of an Arraty transducer steers the beam up or down\?
Definition
Electronic slope
Term
what is the purpose of using coupling gel to scan?
Definition
gel furthers the % of sound transmitted into and out of the body

- transmission(AKA) main BANG at the skin surface
Term
what does the indirect pieozoelectric effect sound?
Definition
turns electrical energy into acoustic energy.
Term
which transducer has the focus that is preset at a fixed point?
Definition
Mechanical Transducer
Term
A convex sequential Array Transducer will have what type of image format?
Definition
Blunted Sector shaped
-rockettop
Term
in which scenario wouls multiple focal zones be advised?
Definition
Superficial structures
-(small parts)
Term
An Annular transducer that has element damage will appear which way on the ultrasound display?
Definition
horizontal band of dropout
Term
when a liner switched Array transducer has one of the element damgae, how will this affect the ultrasound image on the display
Definition
band of dropout extending from th etop to the bottom of the image
Term
which term refer to Axial Resolution?
Definition
longitudinal, Range , Radial Depth

L.A.R.R.D
Term
what should you increase to increase the Near Zone length?
Definition
Depth
Term
what is the Axial Resolution equal to?
Definition
SPL
2
Term
How is the US beam Steered with an Annular Arry Transducer?
Definition
Meachanical steering
Term
how do you calculate the quality factor mathematically?
Definition
Q-factor = Main frequnecy
bandwidth
Term
what is it called when some types of material are mechanically deformed and create a voltage?
Definition
piezoelectric effct
Term
what is lateral Resolution LEAST influnced by?
Definition
(Damping) backing material
Term
what is the best choice in regard to the thickness of the matching layer(s)?
Definition
1/4
a quarter of a wavelength
Term
which array transducer steers the beam Mechanically?
Definition
Annular Phased Arrays.
Term
with a 3.5 MHz Transducer will the Piezoelectric element be thicker or thinner than 7.5 MHz transducer?
Definition
Thicker PZT crystals
Term
what two changes will affect Axial Resolution the most?
Definition
-high Frequency
-pulse damping
Term
A decrease in pulse duration will result in _______ frequency bandwidth
Definition
wide
Term
what is lateral Resolution equal to?
Definition
beam diameter
Term
True or False: in a mechanical scanner there are many active elements which are firing at almost the same time.
Definition
FALSE
Term
what is the name of the material that is plaved behined the rear face of the transducer which reduces pulse duration?
Definition
(backing material)
damping
Term
what is another name for Lateral Resoultion?
Definition
Term
what statement would best describe the focal point?
Definition
where beam diameter is the narrowest
Term
An acoustic lens in front of the piezoelectric crystal is a type of ________ beam focing
Definition
EXTERNAL
Term
ultrasound intensity will vary the nost in which Zone?
Definition
NEAR ZONE
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