Reading...
Play button
Play button
Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
164 Cards in this Set
- Front
- Back
|
The area of a circle that is 2cm in diameter is closed to:
a. 3 squared cm b. 12 squared cm c. 36 squared cm d. 72 squared cm |
a. πr (squared)
π x 1(squared) = 3.14 x 1 = 3 squared cm |
|
|
Simpson's rule is often used in ultrasound to estimate:
a. speed of sound b. distance c. volume d. presence of artifact |
c. volume
|
|
|
Meter, centimeter, and millimeter are all examples of:
a. volume b. area c. distance d. time |
c. distance
|
|
|
The units for circumference and perimeter are ______ or ______
|
cm, mm
|
|
|
The units for area are _____ or ____
|
squared cm, squared mm
|
|
|
The units for volume are ____, ____, _____, _____
|
mL, L, cubic m, cubic cm
|
|
|
Kg, M, kg/cubic meter correspond respectively to which of the following:
a. mass, length, density b. length, mass, density c. mass, length, volume d. weight, length, power e. weight, length, density |
a. mass, length, density
|
|
|
Sound waves are longitudinal and:
a. transverse b. mechanical c. smooth d. electromagnetic |
b. mechanical
|
|
|
The region of low pressure, low density is called:
a. compression b. rarefaction c. transverse d. condensation |
b. rarefaction
|
|
|
The units for density include which of the following:
a. inches b. pounds per sq inch c. kg/cubic meter d. mmHg |
c. kg/cubic meter
|
|
|
All of the following are true statements concerning sound waves except sound:
a. transfers energy b. propagates in a straight line c. travels in a vacuum d. is a longitudinal wave |
c. travels in a vacuum
|
|
|
Sound waves that have peaks that occur at the same time are called:
a. in-phase waves b. out-of-phase waves c. interference d. destructive |
a. in-phase waves
|
|
|
Multiple sound waves that combine and arrive at the same time is called:
a. in-phase waves b. out-of-phase waves c. interference d. destructive |
c. interference
|
|
|
In constructive interference, a pair of in-phase waves combine to form a wave that has a ______ amplitude.
a. smaller b. greater c. equal |
b. greater
|
|
|
In deconstructive interference, a pair of out-of-phase combines to form a wave that has a ____ amplitude.
a. smaller b. greater c. equal |
a. smaller
|
|
|
When interference of waves of difference frequencies occurs, there is a combination of _____ interference and _____ interference.
|
constructive, destructive
|
|
|
The piezoelectric effect:
a. converts sound waves into power b. converts sound waves into voltage c. is most effective when the Curie point is achieved d. occurs only in specialized manmade materials e. does not work in reverse |
b. converts sound waves into voltage
|
|
|
The four acoustic variables are:
|
pressure, density, temperature, particle motion
|
|
|
The 8 acoustic parameters (variables) of a sound wave are:
|
cycle, wavelength, frequency, propagation speed, period, amplitude, bandwidth, decibel
|
|
|
What determines the number of cycles/sec (Hz)?
|
Source (transducer)
|
|
|
Does cycle change over distance/depth?
|
No, however amplitude will diminish.
|
|
|
What is the formula for wavelength?
|
wavelength = propagation speed / frequency
λ = c / f |
|
|
The units for wavelength include all of the following except:
a. inches b. cm c. mm d. µs |
d. µs
|
|
|
Shorter wavelengths are best for _____.
a. Resolution b. Amplitude c. Penetration d. Propagation speed |
a. Resolution
|
|
|
What is the definition of frequency?
|
Number of cycles per second.
|
|
|
What is the formula for frequency?
|
f = c / wavelength
|
|
|
True or False
Frequency and wavelength have a direct relationship. |
False, they have an inverse relationship.
|
|
|
The frequency range for an audible sound is:
a. less than 20 Hz b. 20 Hz - 20,000 Hz c. greater than 20 Hz d. 2 MHz - 10 MHz |
b. 20 Hz - 20,000 Hz
|
|
|
Wavelength for a 3 MHz probe for soft tissue is:
a. 0.5 mm b. 1.0 mm c. 1.5 mm d. 2.0 mm |
a. 0.5 mm
|
|
|
As frequency increases, wavelength _____
a. increases b. decreases c. varies d. cannot be predicted |
b. decreases
|
|
|
Propagation speed is determined by the _____
a. source b. medium c. source and sonographer d. sonographer |
b. medium
|
|
|
The propagation speed of ultrasound is directly proportional to the medium's ______.
a. thickness b. impedance c. bulk modulus (stiffness) d. appearance |
c. bulk modulus
|
|
|
What neutralizes the peizoelectric properties of ultrasound crystals?
a. excessive exposure to vibration b. excessive exposure to heat c. excessive exposure to patient contact d. excessive exposure to coupling gel e. excessive exposure to cold |
b. excessive exposure to heat
|
|
|
The matching layer of the transducer
a. provides an acoustic impedance midway between that of the crystal and the soft tissue b. has a difference acoustic impedance than the material c. is usually made of PZT d. enhances reverse transmission e. serves to reduce spatial pulse length and thus dampen the signal |
a. provides an acoustic impedance midway between that of the crystal and the soft tissue
|
|
|
The backing material of an ultrasound transducer
a. provides an acoustic impedance midway between that of the crystal and the soft tissue b. has a different acoustic impedance than the material c. is usually made of PZT d. enhances reverse transmission e. serves to reduce spatial pulse length and thus dampen the signal |
e. serves to reduce spatial pulse length and thus dampen the signal
|
|
|
The ideal transducers uses the
a. lowest frequency possible while providing adequate spatial resolution in the far field b. lowest frequency possible while providing adequate spatial resolution in the near field c. highest frequency possible while providing adequate spatial resolution in the near field d. lowest frequency possible while providing adequate temporal resolution in the near field e. highest frequency possible while providing adequate spatial resolution in the far field |
e. highest frequency possible while providing adequate spatial resolution in the far field
|
|
|
The conversion of an incident pressure wave to an electrical signal is the
a. Curie effect b. Piezoelectric effect c. Doppler effect d. Huygens effect |
b. Piezoelectric effect
|
|
|
What is the optimal thickness for the matching layer?
a. equal to the thickness of the crystal b. 1/4 of the wavelength c. 1/2 of the wavelength d. 1/2 the width of the backing material |
b. 1/4 of the wavelength
|
|
|
The most commonly used material in the modern transducer element is
a. tungsten powder and epoxy resin b. quartz c. rubber d. lead zirconate titanate |
d. lead zirconate titanate
|
|
|
In an imaging transducer, the purpose of the backing material is
a. increase bandwidth b. decrease the Q factor c. improve image quality d. increase the frequency |
c. improve image quality
|
|
|
A pulsed ultrasound transducer has a resonant frequency of 5 Mhz. The lowest frequency found in the pulse if 2 Mhz and highest is 8 Mhz, what is the bandwidth?
a. 6 Mhz b. 8 Mhz c. 3 Mhz d. 5 Mhz |
a. 6 Mhz
|
|
|
Which of the following crystals (elements) will produce a sound pulse with the lowest frequency
a. Thin PZT element with a low propagation speed b. Thin PZT element with a high propagation speed c. Thick PZT element with a low propagation speed d. Thick PZT element with a high propagation speed |
c. Thick PZT element with a low propagation speed
|
|
|
The center frequency is determined by the ________ of the element and _______ ______ of the element.
|
thickness, propagation speed
|
|
|
The ______ frequency is the preferred frequency of the element.
|
center (or resonance)
|
|
|
The formula used to determine center (resonance) frequency is
|
propagation speed (of element) / 2 x thickness (of element)
|
|
|
The ______ layer is placed on the surface of the elements to reduce the impedance difference between the elements and the soft tissue.
|
matching
|
|
|
The optimal impedance value for the matching layer is the ______ between the elements and the soft tissue.
|
mean
|
|
|
Snell's law is a mathematical description of
a. refraction b. absorption c. resolution d. reflection |
a. refraction
|
|
|
Attenuation of ultrasound in soft tissue is closest to
a. 1 dB/cm/Mhz b. 2 dB/cm/Mhz c. 1 dB/cm/10Hz d. 1 dB/Mhz |
a. 1 dB/cm/Mhz
|
|
|
At a soft tissue-air interface, what percentage of ultrasound is reflected
a. 0% b. near 1% c. 50% d. near 100% |
d. near 100%
|
|
|
______ is a redirection of ultrasound as a result of interaction with red blood cells
a. refraction b. scattering c. Rayleigh scattering d. Rayleigh reflection |
c. Rayleigh scattering
|
|
|
_____ is a redirection of ultrasound as a result of a rough boundary between two medials
a. refraction b. scattering c. reflection d. Rayleigh scattering |
b. scattering
|
|
|
The rayl is a unit for ______
a. reflection b. density c. intensity d. impedance |
d. impedance
|
|
|
If the angle of incidence was 56 degrees, this would represent
a. oblique incidence b. perpendicular incidence c. sagittal angle d. orthogonal incidence |
a. oblique incidence
|
|
|
For soft tissue, the approximate attenuation coefficient in dB/cm is equal to one half the ______ of the transducer
a. wavelength b. impedance c. reflection d. frequency |
d. frequency
|
|
|
The attenuation coefficient of a substance is 2 dB/cm at 1 Mhz. How much would a 3 Mhz sound beam traveling through 10 cm of the substance be attenuated
a. 2 dB b. 6 dB c. 10 dB d. 60 dB |
d. 60 dB
|
|
|
What is the expected attenuation coefficient in soft tissue of a 2 Mhz transducer
a. 1 dB/cm b. 2 dB/cm c. 2.5 dB/cm d. 5 dB/cm |
a. 1 dB/cm
|
|
|
What is the expected attenuation coefficient in soft tissue of a 5 Mhz transducer
a. 1 dB/cm b. 2 dB/cm c. 2.5 dB/cm d. 5 dB/cm |
c. 2.5 dB/cm
|
|
|
Which sequence correctly arranges the materials according to their attenuation coefficients from lowest to highest
a. lung, water, liver, bone b. bone, water, liver, lung c. water, bone, liver lung d. water, liver, bone, lung |
d. water, liver, bone, lung
|
|
|
At which interface would you expect the strongest echo to appear
a. fat/liver b. muscle/blood c. air/skin d. bladder/urine |
c. air/skin
|
|
|
In soft tissue, the attenuation coefficient is estimated to be _____ of the frequency of the transducer
a. same b. half c. twice d. four times |
b. half
|
|
|
In order to produce refraction at an interface, which two conditions must be bet
a. oblique incidence, different acoustic impedances b. perpendicular incidence, different acoustic impedances c. oblique incidence, different propagation speeds d. perpendicular incidence, different propagation speeds |
c. oblique incidence, different propagation speeds
|
|
|
When reflection is 90 degrees, the amount of sound transmitted is routinely ______ % and the amount reflected is _____ %
a. 50:50 b. 99:1 c. 1:99 d. 30:70 |
b. 99:1
|
|
|
z = p x c is the formula used to calculate
a. refraction b. acoustic impedance c. attenuation coefficient d. amount of reflection |
b. acoustic impedance
|
|
|
What is the unit used to describe attenuation
a. dB b. mm c. dB/cm d. Hz |
a. dB
|
|
|
What are the 3 factors that affect attenuation
a. absorption, reflection, scattering b. lateral, axial, elevation resolution c. pulse duration, beam width d. frame rate, beam divergence |
a. absorption, reflection, scattering
|
|
|
______ is an example of the best scatter
|
Lung
|
|
|
______ is the best reflector
|
Bone
|
|
|
Scatter reflectors are _____ than the wavelength
|
smaller
|
|
|
Specular reflectors are ______ than the wavelength.
|
greater
|
|
|
All of the following will increase backscatter except increasing
a. transmit frequency b. scatter intensity c. scatter acoustic mismatch d. smoothness of reflector |
d. smoothness of reflector
|
|
|
The type of reflector that is used for ultrasound tissue characterization is
a. specular b. scatter c. refracted d. interface |
a. specular
|
|
|
Doppler shift is determined by which type of reflectors
a. specular b. non specular c. Rayleigh scattering d. scatter |
c. Rayleigh scattering
|
|
|
______ are reflections returned from scatter reflectors
|
Rayleigh scattering
|
|
|
______ are reflectors and/or rough surfaced
|
Scattering
|
|
|
All of the following are examples of specular reflectors except
a. red blood cells b. diaphragm c. mitral valve d. kidney boundary |
a. red blood cell
|
|
|
Specular reflectors are highly _____ dependent.
|
angle
|
|
|
_____ reflectors are large and smooth surfaced.
|
specular
|
|
|
The main cause of attenuation in soft tissue is _____.
|
absorption
|
|
|
______ is the conversion of sound energy to heat.
|
Absorption
|
|
|
Attenuation is directly proportion to
a. frequency b. propagation speed c. reverberation d. transducer type |
a. frequency
|
|
|
Determine Half Intensity Depth (HID) for a 3 Mhz transducer in soft tissue.
|
HID = 6/f or 3/attenuation coefficient
6/3=2 cm |
|
|
What is the formula for Half Intensity Depth/Half value thickness layer/half boundary layer?
|
HID = 6/f or 3/attenuation coefficient
|
|
|
The _____ _____ _____ is the distance where the intensity is decreased to 1/2 its beginning value.
|
Half Intensity Depth
|
|
|
What ultrasound machine control compensates for attenuation?
|
Transmit Gain Compensation (TGC)
|
|
|
Attenuation is directly proportional to
a. depth of penetration b. propagation speed c. reverberation d. transducer type |
a. depth of penetration
|
|
|
As frequency increases, total attenuation
a. increases b. decreases c. varies d. can not be predicted |
a. increases
|
|
|
The total attenuation for a 10 MHz transducer in soft tissue at 2 cm is
a. 3 dB b. 6 dB c. 9 dB d. 10 dB |
d. 10 dB
Total attenuation = f/2 x depth |
|
|
The attenuation coefficient is dependent on the
a. refraction b. frequency c. path length (distance) d. reflection |
c. path length (distance)
|
|
|
Determine the attenuation coefficient for a 2 MHz transducer assuming soft tissue
a. 1 dB/cm b. 1.5 dB/cm c. 2 dB/cm d. 2.5 dB/cm |
a. 1 dB/cm
Attenuation coefficient = f/2 |
|
|
As depth of imaging increases, attenuation
a. increases b. decreases c. varies d. can not be predicted |
a. increases
Attenuation and Depth are directly related |
|
|
How do you overcome attenuation?
|
1. Use lower frequency transducers
2. Use transmit gain compensation (TGC) |
|
|
There is normal incidence. The acoustic impedance in medium 1 is 1.3 Megarayls. The acoustic impedance of medium 2 is 1.3 Megarayls. There will be no
a. attenuation b. reverberation c. transmission d. refraction |
d. refraction
No refraction because of 90 degrees, no reflection because the mediums have the same properties. |
|
|
The propagation speed in medium 1 is 1530 m/sec. The propagation speed in medium 2 is 1530 m/sec. The incidence angle is 90 degrees. The transmission angle will be
a. 90 degrees b. less than 90 degrees c. greater than 90 degrees d. can not be predicted |
a. 90 degrees
|
|
|
The propagation speed of medium one is 1510 m/s. The propagation speed of medium 2 is 1630 m/s. The incidence angle is 33 degrees. The reflected angle will be
a. greater than 33 degrees b. less than 33 degrees c. equal to 33 degrees d. can not be predicted |
c. equal to 33 degrees
The angle created by an oblique incidence always equals the reflected angle. |
|
|
Snell's law governs
a. reflection b. refraction c. reverberation d. resolution |
b. refraction
|
|
|
An incidence angle of 68 degrees is
a. normal b. oblique c. orthogonal d. direct |
b. oblique
|
|
|
_______ is the change in sound direction while sound crosses a boundary.
|
Refraction
|
|
|
All of the following determine the percentage of reflection except
a. frequency b. impedance c. acoustic mismatch d. acoustic impedance differences |
a. frequency
|
|
|
At soft tissue-soft tissue interfaces, the percentage of energy reflected is approximately
a. less than 1% b. 40% c. 60% d. 99% |
a. less than 1%
|
|
|
At soft tissue-air interface, the % of sound reflected is
a. 1% b. 25% c. 50% d. 99% |
d. 99%
|
|
|
At soft tissue-bone interface, the % of energy reflected is
a. less than 1% b. 20% c. 60% d. 99% |
c. 60%
|
|
|
At a soft tissue-bone interface, the % of energy transmitted is approximately
a. less than 1% b. 40% c. 60% d. 99% |
b. 40%
|
|
|
All of the following are true statements concerning acoustic impedance except
a. for perpendicular incidence (90 degrees), a reflection will occur at the boundary of two media if there is an acoustic impedance mismatch b. represents a material's resistance to sound wave propagation c. acoustic impedance increases as a medium's stiffness increases d. directly related to a material's propagation speed and stiffness e. less sound energy will be reflected when there is a significant acoustic impedance difference between two materials |
e. less sound energy will be reflected when there is a significant acoustic impedance difference between two materials
|
|
|
As propagation speed and density values increase, impedance
a. increases b. decreases c. varies d. can not be predicted |
a. increases
|
|
|
The formula for impedance is?
|
z = c x p
rayls = propagation speed x density |
|
|
Which of the following terms does not belong with the others?
a. low duty factor b. shallow imaging c. low PRF d. long PRP |
b. shallow imaging
|
|
|
Which of the following terms does not belong with the others
a. high duty factor b. shallow imaging c. low PRF d. short PRP |
c. low PRF
|
|
|
If all others factors remain unchanged, what happens to the duty factor when the sonographer uses a transducer with a longer pulse duration?
Increases/Decreases/Remains the same |
Increases
|
|
|
If all other factors remain unchanged, what happens to the duty factor when the PRP increases?
Increases/Decreases/Remain the same |
Decreases
|
|
|
If all other factors remain unchanged, what happens to the duty factor when imaging depth increases?
Increases/Decreases/Remains the same |
Decreases
|
|
|
If all other factors remain unchanged, what happens to the duty factor when the PRF increases?
Increases/Decreases/Remain the same |
Increases
|
|
|
The actual amount of time an ultrasound system spends emitting ultrasound is
a. PRF B. PRP C. PD D. DF |
d. duty factor
|
|
|
The percentage of time spent transmitting in clinical imaging is approximately
a. 1% b. 25% c. 50% d. 99% |
a. 1%
|
|
|
All of the following will increase duty factor except
a. PRF b. imaging depth c. pulse duration d. period |
b. imaging depth
|
|
|
Duty factor is determined by the ______ & _______.
|
Source and depth
|
|
|
Which transducer uses multiple elements, then beam is electronically focused and shaped, and yields a retangular format?
a. linear b. sector c. mechanical d. curved linear e. annular |
a. linear
|
|
|
Which of the following is best described as mechanically steered and multifocus?
a. annular phased array transducer b. annular sequential array transducer c. mechanical transducer d. linear phased array |
a. annular phased array transducer
|
|
|
________ resolution is the ability to resolve two closely spaced structures that are perpendicular to the sound beam.
|
Lateral
|
|
|
Lateral resolution may also be called _______, _______, ______
|
azimuthal, transverse, angular
|
|
|
The units for lateral resolution is most commonly expressed in _____.
|
mm
|
|
|
Lateral resolution is best in ______.
a. near field b. focal zone c. focus d. far zone |
c. focus
|
|
|
Lateral resolution may be improved by all of the following except
a. increasing the transducer diameter b. increasing the transducer frequency c. focusing d. decreasing the element curvature |
d. decreasing the element curvature
|
|
|
Lateral resolution is directly dependent on
a. diameter b. angulation c. refraction d. reflection |
a. diameter
|
|
|
Longitudinal resolution may also be called _____, ______, _____, _____
|
axial, radial, range, depth
|
|
|
The most common units to express axial resolution is _____
|
mm
|
|
|
The formula for axial resolution is
|
SPL / 2
or n x wavelength |
|
|
Which of the following statements about axial resolution is true
a. it is the ability to resolve between two structures in a plane that is perpendicular to the beam b. it is also known as longitudinal, range resolution, and depth resolution c. it increases with increased pulse repetition d. it is unaffected by damping e. it increases with narrower bandwidths |
b. it is also known as longitudinal, range resolution, and depth resolution
|
|
|
Which of the following statements about lateral resolution is true
a. it is the ability to resolve between two parallel structures b. it is dependent on beam width c. it improves with lower frequency d. it is equal to d2/4λ e. it decreases with larger transducer diameters |
b. it is dependent on beam width
|
|
|
Matrix array transducers decrease slice thickness which improves ______ resolution.
a. axial b. temporal c. elevational d. radial |
c. elevational
|
|
|
Matrix array transducers provide a longer focal zone which improves ______ resolution.
a. lateral b. axial c. range d. temporal |
a. lateral
|
|
|
The _____ array transducers arranges the elements in rows and columns.
a. annular b. phased c. linear sequenced d. vector e. matrix |
e. matrix
|
|
|
An annular array's beneficial features include all of the following except
a. improved resolution b. mechanical function c. focusing at all depths |
b. mechanical function
|
|
|
The type of transducer that steers the beam mechanically is known as
a. linear array b. curved array c. annular array d. phased array |
c. annular array
|
|
|
If you wish to produce a sonogram in a rectangular format, which transducer should you chose
a. annular array b. linear array c. phase array d. convex array |
b. linear array
|
|
|
Which of the following transducers is electronically focused by mechanical steering
a. convex linear array b. phased linear array c. annular array d. sequential linear array |
c. annular array
|
|
|
Linear sequenced arrays are
a. beam steered b. small transducers c. electronically focused d. mechanically focused |
c. electronically focused
|
|
|
The sonographer can determine which of the following when imaging with a sector phased array
a. focal length b. beam steering c. receive focus d. dynamic focusing |
a. focal length
|
|
|
The image display by the convex sequenced array is
a. rectangle b. pie shaped c. blunted sector d. trapezoidal |
c. blunted sector
|
|
|
All of the following are true statements concerning the linear sequenced array and convex sequenced array except
a. both are mechanical focused b. both are arc shaped c. both are sequentially fired d. both are electronic transducers |
a. both are mechanical focused
|
|
|
Which of the following transducers creates a cross-sectional image by firing a group of elements in succession
a. linear phased array b. linear sequenced array c. wobbler d. linear translating |
b. linear sequenced array
|
|
|
Which of the transducers is best described as mechanically steered and fixed, single focus
a. annular phased array b. annular array c. mechanical d. linear phased |
c. mechanical
|
|
|
The sector phased array is primarily focused
a. electronically b. mechanically c. externally d. can not be predicted |
a. electronically
|
|
|
Which of the following states describes annular array transducer
a. electronically focused in two dimensions and mechanically steered b. electronically focused along the length of the array, mechanically focused along width & electronically steered c. electronically focused along the width of the array, mechanically focused along the length of the array & unsteered d. mechanically focused in two dimensions and mechanically steered |
c. electronically focused along the width of the array, mechanically focused along the length of the array & unsteered
|
|
|
Dynanic receive focusing uses
a. mechanical means to focus the beam b. time delays to excite the array elements c. variable number of elements to form the transmitted beam d. delay lines after the echoes are detected in the array elements |
d. delay lines after the echoes are detected in the array elements
|
|
|
Electronic _____ focusing is accomplished during pulse transmission and beam formation
a. receive b. dynamic c. elevational d. transmit |
d. transmit
|
|
|
The type of focusing that uses receive delay lines is called
a. dynamic b. transmit c. mechanical d. internal |
a. dynamic
|
|
|
The sonographer can change the focal length in which of the following
a. receive b. dynamic c. mechanical d. transmit |
d. transmit
|
|
|
A curved element is called which type of focusing
a. receive b. electronic c. internal d. dynamic |
c. internal
|
|
|
Internal and external focusing may also be called
a. delay b. electrical c. mechanical d. longitudinal |
c. mechanical
|
|
|
Electronic _____ focus is accomplished while the sound beam exits the transducer
|
transmit
|
|
|
A disadvantage of multiple transmit zones is
a. poor lateral resolution b. slow frame rate c. narrow beam width d. mechanical stress |
b. slow frame rate
|
|
|
At the focal point, the beam diameter is _____ the transducer diameter.
a. equal to b. double c. half d. one-fourth |
c. half
|
|
|
If the frequency of a transducer is increased, the near field length is
a. increased b. unchanged c. decreased |
a. increased
|
|
|
In an ultrasound beam pattern, the point of divergence and beyond is called the
a. fresnel zone b. fraunhoffer zone c. refraction d. curie point |
b. fraunhoffer zone
|
|
|
A 6 mm diameter unfocused transducer will have a _____ than a 19 mm diameter unfocused transducer of the same frequency
a. narrower in the near field b. longer near field c. narrower angle of divergence d. longer focal zone |
a. narrower in the near field
|
|
|
The near field of a 4 MHz unfocused transducer will be _____ as the near field of a 2 MHz unfocused transducer
a. half as long b. same length c. twice as long d. four times as long |
c. twice as long
|
|
|
A 3.5 MHz focused transducer will have _____ focal zone compared to a 2.5 MHz focused transducer of the same shape and size
a. shorter b. longer c. equivalent d. an indistinct |
b. longer
|
|
|
In order to focus a sound beam relatively far away from the transducer, it is advantageous to _______ of the element
a. increase the thickness b. increase the diameter c. increase the temperature d. decrease the diameter |
b. increase the diameter
|
|
|
Which of the following are characteristic of the focal zone
a. pulse duration, beam width, focal area b. depth of focus, point of maximum intensity, beam width c. beam width, point of max intensity, focal area d. depth of focus, point of max intensity, focal area e. pulse duration, point of max intensity, focal area |
d. depth of focus, point of max intensity, focal area
|
|
|
Which of the following transducers creates a sound beam that will diverge the least in the far field
a. 5mm element thickness b. 10 mm element thickness c. 10 mm element diameter d. 5mm element diamer |
c. 10mm element diameter
|
|
|
The area of greatest resolution is
a. near field b. far field c. focal zone d. all of the above |
c. focal zone
|
|
|
What is the diameter of the focal point
a. 1/2 the diameter of the transducer face b. 1/4 the diameter of the transducer face c. equal to the diameter of the transducer d. twice the diameter of the transducer |
a. 1/2 diameter of the transducer face
|
|
|
Increasing the transducer diameter has which of the following effects
a. increases near zone length b. increases frequency c. increases the diameter in the far field d. A & C |
d. A & C
|
