Physics Test Questions

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dorkfork
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Physics Test Questions
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2014-11-06 18:53:53
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Ultrasound Physics Songraphy
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Physics Exams Questions
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  1. What type of medium has has the highest absorption coefficient? (air, bone, or soft tissue(water)
    Bone
  2. The propagation speed is fastest in? (soft tissue, bone or air)?
    Soft tissue
  3. For soft tissue, if the path length is doubled, total attenuation will:
    Double
  4. If the attenuation coefficient for muscle is 5.0 dB at 3MHz, what is the attenuation coefficient at 6MHz?
    10
  5. The portion of sound energy redirected towards the sound source is called:
    Reflected
  6. If the acoustic output is set at 0 dB, this indicates:
    Reference intensity level
  7. If the half value layer thickness for muscle is 4cm at 2MHz, the HVL thickness at 4MHz is ___cm.
    2
  8. If the amplitude is increased by a factor of 2, intensity:
    Increases by a factor of 4
  9. The maximum pressure variation that occurs in a cycle is termed:
    Amplitude
  10. An ultrasound field in soft tissue experiences an intensity reduction of 9 dB. This is equivalent to ____ Half Intensity Depth(s).
    3
  11. The tissue property that determines the amount of refraction at an interface is:
    Velocity
  12. If the reflection intensity coefficient at an interface is 25%, what is the transmission intensity coefficient?
    75
  13. Acoustic impedance is equal to:
    Density x velocity
  14. The propagation speed through the medium is NOT dependent on:
    Frequency
  15. If the initial intensity is reduced to 25%, this is equivalent to ____ dB.
    6
  16. Which of the following is an example of a specular reflector?
    Diaphragm
  17. If the acoustic power is doubled, intensity will:
    Double
  18. If the wavelength is decreased by 1/4 , the frequency will:
    increase by 4
  19. What is the typical transmission coefficient at a soft tissue/air interface?
    0.1
  20. As the temperature decreases, the propagation speed in tissues would:
    Decrease
  21. If the total attenuation at 2 MHZ = 20 dB, the total attenuation at 4 MHz is ____ dB.
    40
  22. Which of the following accounts for the greatest portion of the attenuation rate at an air/soft tissue interface?
    Reflection
  23. Which of the following types of media would have the highest characteristic acoustic impedance value?
    soft tissue/air (99.9% reflected back)
  24. Decreasing the beam area to 1/6 of the original will result in:
    increasing intensity
  25. Which of the following conditions is most likely to produce the greatest amount of refraction? (0 degrees = normal incidence)
    Muscle/bone interface - 20 degree incidence
  26. If the wavelength for a sound field = 2 mm, which of the following interfaces would most likely behave as a specular reflector?
    4.0 mm
  27. If the wavelength for a sound field is 1 mm, which of the following reflectors would behave as a non-specular reflector?
    0.5 mm
  28. If the transmission coefficient is 60% at an interface, the reflection coefficient is:
    40
  29. Which of the following would have the lowest absorption coefficient?
    Water
  30. Which of the following mediums would have the largest half intensity depth in cm?
    soft tissue
  31. The sonographic pattern displayed distal to a region with a low attenuation rate is termed:
    Enhancement
  32. What is the typical per cent reflection at a muscle/bone interface?
    50
  33. Which of the following factors accounts for the greatest portion of the attenuation rate in soft tissue?
    Absorption
  34. If the acoustic output is increased by 9 dB, the resulting intensity has increased by a factor of:
    8
  35. The theory/principle that relates the angle of incidence to the angle of refraction is:
    Snell's law
  36. A large amplitude pulse (voltage) from the pulser results in:
    Increasing transmit intensity
  37. Which control changes the intensity of the transmitted pulse?
    Acoustic power
  38. Increasing the pulse repetition frequency will:
    Decrease the maximum imaging depth
  39. The primary method that the sonographer uses to control frame rate during real time imaging is:
    Imaging depth
  40. The initial amplitude is determined by :
    Acoustic power control
  41. According to the range equation, which of the following are required to calculate the distance to the reflector?
    Propagation speed and round trip time
  42. The signal processing function that eliminates the negative component of the signal is termed:
    Rectification
  43. The System Gain function is performed in the:
    Beam former
  44. Reflector B is twice the distance from the transducer as reflector A. It takes ______ times as long for an echo to arrive from reflector B as from reflector A.
    2
  45. The sonographer has increased the size of the sector width to image a large mass. What can the sonographer do to maintain the same temporal resolution before this adjustment?
    Decrease the number of focal zones.
  46. Increasing the number of scan lines per frame improves:
    Detail resolution
  47. If the gain is increased by 9 dB, the power has been increased by a factor of:
    8
  48. Adjusting the TGC controls affects the settings in the:
    Beam former
  49. Which of the following transducer arrays utilizes electronic beam steering?
    Sector
  50. On an A-Mode display, the height of the spike represents:
    The echo intensity
  51. The computer parameter that limits the number of gray levels available to display on the image matrix is:
    Number of bits in computer word
  52. Which of the following system components generates the signals to focus and steer the sound field?
    Beam former
  53. The pulse repetition period is the reciprocal of:
    Pulse repetition frequency
  54. In cardiac imaging, reducing the size of the sector angle will:
    Increase the frame rate
  55. The ability to distinguish between adjacent structures producing echo amplitudes of similar amplitude is termed:
    Contrast resolution
  56. The typical dynamic range in the amplifier is:
    60-100
  57. What is the maximum number of displayed shades of gray in a 7-bit processor?
    128
  58. Which of the following digital scan converters would display the best contrast resolution?
    8 bit
  59. In which of the following modes is time the unit of measurement on one axis?
    M-mode
  60. How many levels of information can a single bit represent?
    2
  61. Preprocessing programs are performed in the:
    Image processor
  62. Postprocessing programs are performed in the:
    Display
  63. The use of cine loop will primarily improve _________ resolution
    Temporal
  64. During real time imaging, if the scan line density is reduced to 1/4, the maximum frame rate is:
    Increased by a factor of 4
  65. In clinical applications, maximum reflection amplitude occurs with:
    Normal incidence
  66. At a muscle/fat boundary, the percentage of sound energy reflected will be:
    60 %
  67. As sound propagates through the medium, amplitude:
    Decreases
  68. As frequency increases, half intensity depth:
    Decreases
  69. Propagation speed is determined by the:
    Medium
  70. By altering the imaging depth, the period of the wave:
    Remains unchanged
  71. At a soft tissue/air interface, the percentage of sound transmitted will be:
    0.1%
  72. Determine the power if the amplitude of the wave is 4.
    • 16 = 42
    • Power = amplitude2
  73. The _______ is a unit of measurement used to express the difference or ratio between two variables.
    decibel
  74. The sonographer can change the sound field intensity by manipulating:
    Transmit power
  75. For soft tissue, which of the following would most likely be used to represent a 50% reduction in intensity?
    -3 dB
  76. The total attenuation for a 10 MHz sound field in soft tissue at 2 cm is _____ dB.
    10dB
  77. Increasing intensity increases
    Propagation speed
  78. At soft tissue interfaces, the percentage of ultrasound energy transmitted is approximately _____ %,
    99
  79. Which of the following has an average propagation speed of 1.54 mm/µs?
    Muscle, soft tissue
  80. As sound propagates through the medium, intensity:
    Decreases
  81. Frequency is determined by the:
    Piezoelectric element
  82. The best example of a Rayleigh scatterer is:
    Red blood cell
  83. The initial amplitude is determined by :
    Acoustic power control
  84. As propagation speed and density values increase, acoustic impedance:
    Increases
  85. Determine the attenuation coefficient in dB/cm for a 10 MHz sound field in soft tissue.
    10dB/cm
  86. The attenuation rate will increase if there is an increase in:
    frequency
  87. A region of high pressure, high density is:
    Compression
  88. Wavelength is determined by the:
    • Frequency
    • (increase frequency to decrease wavelength)
  89. To maximize reflection from a specular reflector, the sonographer should strike the interface at ______ degrees.
    90
  90. This artifact cannot occur at perpendicular incidence
    Refraction
  91. As sound propagates through a medium, power:
    Decreases
  92. A sound beam's wavelength is 0.5 mm. Which of the following would be an example of a nonspecular reflector?
    0.4 mm
  93. Impedance is equal to:
    c x p
  94. For an unfocused circular soundfield, the crystal diameter is 30 mm. What is the beam diameter in mm at a depth equal to twice the near field length?
    30
  95. Elevational resolution is related to:
    Beam width
  96. The intensity of a focused beam is generally:
    Highest in the focal zone
  97. The product of the period and the number of cycles in the pulse is:
    Pulse duration
  98. Axial resolution can be improved by using:
    Higher frequency transducers
  99. The type of real-time transducer that employs a combination of electronic focusing and mechanical steering is:
    Vector array
  100. The reverse piezoelectric effect is best described as:
    Mechanical deformation resulting from high voltage applied on crystal faces, generating ultrasound
  101. Which of the following transducers would be most useful for imaging superficial structures?
    5 MHz, superficial focus
  102. Lateral resolution is equal to:
    Beam area
  103. The unit of measurement for the duty factor is:
    Percent
  104. Increasing the pulse repetition period:
    Increases the maximum imaging depth that can be imaged
  105. For an unfocused sound field utilizing a 10 mm crystal diameter, the sound field diameter at the end of the near field will be ____ mm.
    5
  106. Grating lobes in electronic array systems:
    Are controlled with a process called subdicing
  107. As frequency increases, the beam width will:
    Decrease
  108. The principle that states that all points on a wavefront can be considered as point sources for the production of spherical secondary wavelets was postulated by:
    Huygen
  109. The ____ relates the bandwidth to operating frequency
    Quality factor
  110. For an unfocused circular sound field, the crystal diameter is 40 mm. What is the beam diameter 1cm from the crystal surface in mm?
    40
  111. The piezoelectric properties of the transducer will be lost if the crystal is heated above the:
    Curie point
  112. What is the most commonly used material for ultrasound transducer crystal elements?
    Lead zirconate titanate
  113. A decreased pulse duration produces:
    Better axial resolution
  114. The beam of an unfocused transducer diverges where?
    • In the Fraunhofer zone
    • Far Field
  115. The amount of divergence in the far field can be decreased by:
    Increasing the frequency or a larger crystal diameter
  116. The near field length of an unfocused transducer depends on:
    Frequency and diameter
  117. Extraneous sound energy emitted from a linear sequenced array are called:
    • Grating Lobes
    • Corrected by subdicing
  118. The spatial pulse length:
    Decreases with increasing frequency
  119. Transmit delay focusing in a linear array transducer will improve:
    Lateral resolution
  120. Axial resolution depends on the ______
    wavelength/frequency (higher frequency/shorter wavelength)
  121. The damping material will improve
    Increase damping material>>shorter pulse>>wider bandwidth>>better axial resolution
  122. A long near zone can be obtained by:
    Increase frequency (decrease λ)
  123. Higher the ____ the shorter the SPL
    Frequency
  124. Shorter the SPL the better the ____ resolution
    axial
  125. SPL=
    • SPL= λ x # of cycles in pulse
    • Shorter the SPL the better the axial resolution
    • Higher the frequency the shorter the SPL
  126. Longitudinal or axial resolution is directly dependent on:
    • Spatial pulse length
    • SPL= λ x # of cycles in pulse
    • Shorter the SPL the better the axial resolution
    • Higher the frequency the shorter the SPL
  127. Generally, ultrasound transducers have better _____ resolution than ________ resolution.
    Better axial resolution than lateral resolution
  128. Which equipment assumption is violated when refracted echo information is processed?
    All echoes come from straight ahead
  129. To reduce the Mechanical Index (MI), the sonographer would:
    Decrease acoustic power, increase the number of focal zones
  130. Mechanism through which ultrasound energy can produce a biological effect
    Stable caviatation, transient cavitation, increase in temperature
  131. The artifact indicated by " A" is indicates:
    Large acoustic impedance missmatch
  132. If the focal zone is decreased to 1/5 of its original area, the intensity will:
    Increase by 5
  133. Which rod groups scanned from side C would evaluate lateral resolution?
    Rod group C
  134. Side lobe artifact produces which of the following sonographic characteristics?
    • Energy distribution outside main beam profile
    • Horizontal linear extensions from specular reflector (i.e. septa)
  135. The risk of cavitation is considered low when the MI value is ____ or lower.
    0.5
  136. The area of the sound field characterized by violent intensity changes is:
    Near field
  137. Transient cavitation refers to :
    • AKA collapse cavitation or normal cavitation
    • Bubble oscillation so large that the bubble collapses
  138. No thermal effects have been documented when the temperature elevation is below ___ degrees.
    2
  139. A Thermal Index (TI) value of one (1) indicates:
    Potential to increase tissue temperature by 1 degree
  140. The artifact indicated by the white line can be eliminated by:
    Aliasing
  141. Which mode has the potential for the highest thermal production?
    Color doppler
  142. A device commonly used to measure the output of diagnostic ultrasound systems is:
    Hydrophone
  143. A tumor has a slower propagation speed than the soft tissue average propagation speed. This will result in:
    Shadowing
  144. For a given sound field, which of the following would demonstrate the lowest intensity value?
    SATA
  145. What type of tissue is most susceptible to the effects of cavitation?
    • Aerated lung tissue
    • Air in GI tract
  146. With all other parameters constant, increasing the acoustic output by a factor of eight (8) will:
  147. Which artifact is associated with reverberation and resonance in a small gas bubble or surgical staple?
    Comet tail
  148. Which of the following parameters directly relates to heating of tissues?
    • Increase thermal index
    • Increased frequency or output power
  149. Which of the following rod groups scanned from side A would evaluate axial resolution?
    Rod group B
  150. What factors would produce the greatest TI values?
    • High frequency
    • Narrow focal zone
    • Stationary color doppler
  151. What factors would produce the greatest MI values?
    Low frequency, high intensity
  152. The artifact indicated by the arrow is due to:
    • Reverberation/ comet tail
    • Large acoustic impedance missmatch
  153. Which system control manipulations would best limit patient exposure to ultrasound energy?
    • Decrease scan time
    • M-mode vs. color doppler or pulsed wave
    • Decrease frequency
  154. A transducer has a very wide slice thickness. This may produce:
    • Filling defect of a cystic/anechoic structure
    • Filling in of vessels / small cyts
  155. Which of the following produces the split image artifact?
    • fat/muscle interface near the surface
    • i.e. linea alba
  156. Which of the following types of tissue will demonstrate the greatest temperature elevation?
    • embryo <8 weeks conception
    • head, brain, and spine of any fetus or neonate
    • eye in any patient
  157. Which of the following digital scan converters would display the best contrast resolution?
    • 8 bit
    • 8 is the current standard
    • 2= shades of gray, where n = bits in a computer word
  158. Bioeffects have been observed in experimental animals with focused intensities greater than:
    1 W/cm2
  159. On an A-Mode display, the height of the spike represents:
    The echo intensity
  160. The System Gain function is performed in the:
    Beam former
  161. What is the maximum number of displayed shades of gray in a 6-bit processor?
    2= 64
  162. What determines the power of the ultrasound field?
    Voltage applied to the transducer
  163. The typical pulse repetition frequency range for clinical imaging applications is:
    • Low range
    • 10-20kHz
  164. The term signal to noise ratio is:
    The ratio of signal amplitude to the variation in noise
  165. In cardiac imaging, reducing the size of the sector angle will:
    Increase the frame rate
  166. If the imaging depth is quartered, the frame rate will be:
    Quadrupled
  167. The signal processing function that eliminates the negative component of the signal is termed:
    Rectification
  168. Adjusting the TGC controls affects the settings in the:
    Beam former
  169. The ability to distinguish between adjacent structures producing similar echo amplitudes is termed:
    Contrast resolution
  170. When the pulse repetition period is increased:
    Imaging depth is decreased
  171. If the gain is increased by 6 dB, the power has been increased by a factor of:
    4
  172. Which control changes the intensity of the transmitted pulse?
    Acoustic power
  173. Increasing the number of scan lines per frame improves:
    Detail resolution
  174. The use of cine loop will primarily improve _________ resolution
    Temporal
  175. What system component generates the signals to focus and steer the sound field?
    Beam former
  176. When comparing Write magnification with Read magnification, Write magnification:
    Improves spatial resolution compared to read magnification
  177. During real time imaging, if the scan line density is reduced to 1/2, the maximum frame rate is:
    Doubled
  178. Preprocessing programs are performed in the:
    Image processor
  179. If the original acoustic power is 100 mW and the power control is increased by 3 dB, the new power is _____ mW.
    200
  180. In real time systems, the range equation is used to determine reflector:
    Depth
  181. The typical dynamic range in the amplifier is:
    60-100
  182. The sonographer has increased the size of the sector width to image a large mass. What can the sonographer do to maintain the same temporal resolution before this adjustment?
    Decrease the number of focal zones.
  183. Increasing the pulse repetition frequency will:
    Decrease the maximum imaging depth
  184. Reflector B is twice the distance from the transducer as reflector A. It takes ______ times as long for an echo to arrive from reflector B as from reflector A.
    2
  185. The computer parameter that limits the number of brightness levels available to display on the image matrix is:
    Number of bits in computer word
  186. The primary method that the sonographer uses to control frame rate during real time imaging is:
    Imaging depth
  187. Which mode has time the unit of measurement on one axis?
    M-mode
  188. Flow through a blood vessel is determined by:
    • 1. Pressure difference
    • 2. Vascular resistance
  189. Vessel diameter increase as _____ increases.
    Pressure
  190. Veins or arteries, which are more distensible?
    Veins are 6-10 x as distensible as arteries
  191. Arteries
    • Transport blood to tissues
    • High pressure
  192. Arterioles
    • Last, smallest branches of the arterial system
    • Act as "control valves" for blood flow into capillaries
  193. Capillaries
    Exchange between blood and interstital spaces
  194. Vasodilitation occurs when?
    • During exercise
    • After a meal
  195. Vasoconstriction occurs when?
    • In a resting state
    • With fasting
  196. Venules
    Collect blood from capillaries and connect to larger veins
  197. Veins
    • Blood returned to heart
    • Body contians many more veins than all other parts of the vascular system
  198. AO/ICV
    Have the smallest cross-section area and therefore the highest velocity
  199. Relationship of velocity to area
    Velocity is inverse to area
  200. Energy derived from the cardiac pump
    Potential/pressure energy
  201. Potential energy
    • Pressure/stored energy
    • Derived from the cardiac pump
    • Distends vessels and stores energy
  202. Kinetic energy
    • Energy of motion
    • KE < PE due to distensibility of vessels
  203. Kinetic energy can increase due to:
    • Increase in flow>> i.e. exercise
    • Stenosis (increased velocity)
  204. Movement of fluid between 2 points requires:
    • Difference in energy
    • Difference in pressure
  205. Example of low resistance
    • Organs
    • Low resistance = greater energy difference = greater flow
  206. Example of high resistance
    • Resting muscle
    • High resistance = less flow
  207. Pouseuille's law
    Defines relationship between pressure, volume flow, and resistance
  208. The longer the vessel the _____ the resistance.
    • Higher
    • High pressure is required to maintain flow
  209. The shorter the vessel the ____ the flow volume.
    Higher
  210. What has the most significant impact on flow rate?
    • Radius of the vessel
    • Smaller the radius, the higher the resistance
  211. Smaller the radius, the _____ the resistance.
    Higher (and higher pressure)
  212. Plug flow
    • Flat profile
    • Seen in stenotic area
    • Same velocity throughout vessel (slower flow at wall)
  213. Laminar flow
    • Most common flow pattern
    • Seen during systole in smaller arteries
    • Flow in center is highest and gradually tapers as it reaches the wall of the vessel
  214. Disturbed flow is signified by?
    Spectral broadening
  215. Mathematical number to determine when flow turbulence will occur?
    Reynold's number
  216. Reynolds number for when turbulance will occur
    2000 Re or higher
  217. Harmonic resonance produced by flow turbulence transmitted into vessel walls is known as
    audible bruit
  218. Where is normal disturbed flow visualized throughout the cardiac cycle?
    • Bifurcations
    • Curves
  219. Significant stenosis
    70% blockage
  220. Tardus parvus
    Dampened wave forn distal to a stenosis
  221. Monophasic flow
    • Low resistance, continuous and steady throughout S and D
    • Seen in normal arteries that supply low resistance vascular beds -liver, spleen, brain, kidneys
  222. Triphasic flow
    • Highest resistance to flow
    • Antegrade/forward flow during systole
    • Retrograde/reverse flow during diastole
    • Seen in distal AO/iliac arteries
  223. Cosine of the doppler angle is ______ly related to the doppler angle.
    • Inversely related
    • Angle of 0 = cosine 1.00
    • Angle of 90 = cosine 0
  224. Increase transmit frequency and _____ the size of the Doppler shift
    Increase
  225. Decrease velocity of flow and _____ the size of the Doppler shift.
    Decrease
  226. Increase the Doppler angle and _____ the size of the Doppler shift.
    Decrease
  227. Decrease the Doppler angle and ______ the size of the Doppler shift.
    Increase
  228. Cosine = 0
    • 90 degree angle
    • No Doppler shift
  229. Cosine = 1.00
    • 0 degree angle
    • Largest Doppler shift
  230. With spectral analysis the frequency is displayed on which axis?
    Vertical y axis
  231. What is displayed on the X axis of spectral analysis?
    Time
  232. Amplitude or power is displayed as what on spectral analysis?
    Brightness
  233. FFT
    • Fast fourier time
    • Current computer program for analyzing and displaying spectral representation
  234. How can aliasing be eliminated?
    • Increase PRF (increased nyquist limit)
    • Shift baseline
    • Increase size of angle
    • Decrease transmit frequency
  235. Main disadvantage of pulsed Doppler is?
    Aliasing
  236. Nyquist Limit
    • 1/2 the PRF
    • Exceeding this produces aliasing
  237. PRF control
    Changed the number of pulsed emitted per second
  238. Primary advantage of CW Doppler
    No velocity limit/ no aliasing
  239. Main disadvantage of CW Doppler
    • Large fixed sample volume
    • POOR RANGE RESOLUTION
  240. Color Doppler
    • Qualitative, NOT quantitative information
    • Will produce aliasing
    • Good range resolution
    • BART
  241. How to eliminate color aliasing
    • Increase PRF (scale setting)
    • Decrease sample volume depth
    • Use larger Doppler angle
    • Lower transmit frequency
    • Go from triplex(color, image, spectra) to duplex (color, image)
  242. Power Doppler
    • Encodes amplitude of blood cells
    • Provides no info on direction of flow
    • NO aliasing and less angle dependant
  243. Components of pulsed Doppler instrumentation:
    • Pulser
    • Gated detector
    • Spectral analysis
    • Memory
    • Display
    • Speakers
  244. Length of pulses produced by pulser
    5-30 cycles
  245. The time period for acquisition of Doppler signal is determined by the _____.
    Size of the gate
  246. Phase shift means
    Motion is present
  247. Rhythmic cycles or beats produced when waves of different frequencies produce interference are added together and termed
    Beat frequency
  248. Minimum number of cycles per pulse is?
    4
  249. Number of cycles required for fast flow
    6-10
  250. Number of cycles needed for gray scale
    2-3 cycles
  251. Number of cycles needed for slow flow
    20-30
  252. Typical sampling rate
    25,600 times per second
  253. High pass filter
    • Rejects all frequencies below the threshold vaule
    • Usually 100Hz
    • Removes wall thump but not slow flow
  254. Low pass filter
    • Eliminates high frequency noise
    • Improper adjustment can eliminate high frequency (fast) flow
  255. One speed estimate has a _____  pulse minimum.
    Three
  256. More than 3 pulses are required in order to:
    • Improve accuracy of the estimate
    • Determine the variance
    • Improve detection of slow flow
  257. Typical ensemble length range
    10-20 pulse
  258. Increasing ensemble length will ___ frame rate.
    Decrease
  259. Ensemble length
    • AKA pulse packet size
    • The number of pulses required to produce one color scan line

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