Term
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Definition
| any device that converts one form of energy into another |
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Term
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Definition
| the ability of certain materials to create an electrical voltage when they are mechanically deformed |
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Term
| reverse piezoelectric effect |
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Definition
| the ability of certain materials to change shape when voltage is applied |
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Term
barium titanate
lead metaniobate
lead titanate
lead zirconate titanate |
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Definition
| man-made ferroelectric materials |
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Term
| the temperature at which a PZT is polarized; 360ºC/680ºF |
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Definition
What is the Curie Point?
What temperature is it at? |
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Term
quartz
rochelle salts
tourmaline |
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Definition
| natural piezoelectric materials |
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Term
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Definition
| the complete destruction of all micro-organisms |
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Term
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Definition
| What is proper sterile technique for ultrasound transducers? |
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Term
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Definition
| the application of a chemical agent to reduce or eliminate infectious organisms on an object |
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Term
PZT
case
wire
matching layer
damping element
radiofrequency shield
acoustic insulator |
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Definition
| 7 parts of the transducer |
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Term
PZT is 4mm.
Matching layer is 2mm. |
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Definition
| If a wavelength is 8mm, how thick is the transducer's PZT? How thick is its matching layer? |
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Term
| It bridges the impedance gap between the crystal and the skin, allowing for more transmission of sound into the body. |
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Definition
| Why is the matching layer necessary? |
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Term
| epoxy resin impregnanted with tungsten |
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Definition
| What is backing material made of? |
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Term
| shortens SPL and pulse duration, increasing axial resolution |
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Definition
| What are the advantages of using damping element? |
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Term
| bandwidth(Hz) = maximum frequency - minimum frequency |
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Definition
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Term
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Definition
| Do continuous wave transducers have wide or narrow bandwidth? |
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Term
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Definition
| Do pulsed wave imaging transducers have high or low Q-factor? |
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Term
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Definition
| What are the units for quality factor? |
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Term
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Definition
| What is a typical value for Q-factor? |
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Term
Q-factor increases, narrower bandwidth;
Q-factor increases, dampening decreases;
Q-factor increases, pulse length increases |
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Definition
| If Q-factor increases, what happens to bandwidth? To dampening? To pulse length? |
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Term
| Q-factor = center frequency(MHz) / bandwidth (MHz) |
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Definition
| equation for quality factor |
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Term
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Definition
| If a continuous wave transducer has a frequency of 5MHz, what is the frequency of the voltage applied to its crystal? |
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Term
| propagation speed of crystal; thickness of crystal |
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Definition
| What 2 factors determine frequency in pulsed wave transducers? |
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Term
| Thin crystals; the thicker the crystal, the lower the frequency, and in diagnostic imaging one should use the highest frequency available while still being able to image at the depth of the area of interest. |
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Definition
In diagnostic imaging, do we want to use transducers with thick or thin crystals?
Why? |
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Term
| frequency(MHz) = sound speed in PZT (mm/µs) / 2 x PZT thickness(mm) |
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Definition
| equation to determine frequency in pulsed wave transducers |
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Term
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Definition
| the location where the sound reaches the narrowest point; the point of maximum intensity |
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Term
| focal depth, focal length, or near zone length |
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Definition
| the distance from the transducer face to the focus |
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Term
transducer diameter
frequency of sound wave |
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Definition
| What determines focal length? |
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Term
| If the diameter increases or the frequency increases, the focal depth increases. |
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Definition
| If the transducer diameter increases, what happens to the focal depth? If the frequency increases? |
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Term
| near zone, near field, or Fresnel zone |
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Definition
| the region between the transducer and the focus |
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Term
| far zone or Fraunhoffer zone |
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Definition
| the region beyond the near field |
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Term
| transducer diameter and frequency of the sound wave |
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Definition
| What determines the divergence in the Fraunhoffer zone? |
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Term
| When transducer diameter or frequency increases, divergence decreases. |
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Definition
| Does divergence increase or decrease with a larger diameter transducer? With a higher frequency? |
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Term
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Definition
| the region where the beam is narrow and the image is relatively good |
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Term
| The constructive and destructive interference from millions of tiny diffraction patterns; Huygens |
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Definition
| What creates the hourglass shape of the sound beam? Who discovered this? |
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Term
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Definition
| the ability to distinguish two structures that are close to each other along/parallel to the beam's main axis |
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Term
Longitudinal
Axial
Range
Radial
Depth |
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Definition
| What are the other names for axial resolution? |
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Term
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Definition
| What are typical values of LARRD resolution? |
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Term
| Increase dampening, which lessens ringing and produces fewer cycles in a pulse; increase frequency, which shortens the wavelength. |
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Definition
| Axial resolution is determined by spatial pulse length. How can you create short pulses? |
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Term
axial resolution(mm) = SPL(mm) / 2
axial resolution(mm) = wavelength x # of cycles in pulse / 2 |
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Definition
| equations for axial resolution? |
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Term
| axial resolution(mm) = 0.77 x # of cycles in pulse / frequency(MHz) |
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Definition
| equation for axial resolution in soft tissue |
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Term
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Definition
| the ability to distinguish two structures that are close to each other side-by-side or perpendicular to the beam's axis |
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Term
Lateral
Angular
Transverse
Azimuthal |
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Definition
| What are the other names for lateral resolution? |
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Term
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Definition
| What determines LATA resolution? |
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Term
| at the focus; the focus is the narrowest part of the beam |
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Definition
| Where within the sound beam is the best azimuthal resolution? Why? |
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Term
| lateral resolution(mm) = beam diameter(mm) |
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Definition
| equation for LATA resolution |
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Term
| High frequency causes the beam in the far zone to diverge less, producing a narrower beam in the far zone. |
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Definition
| Why does high frequency improve LATA resolution? |
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Term
| High frequency shortens pulse length, improving axial resolution. |
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Definition
| Why does high frequency improve LARRD resolution? |
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Term
| internal and external focusing |
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Definition
| What types of focusing are used with single-crystal transducers? |
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Term
| If focusing increases, the focal zone gets smaller. |
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Definition
| What happens to the focal zone when focusing increases? |
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Term
| fixed/conventional/mechanical focusing |
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Definition
| Which type of focusing produces poorer transverse resolution? |
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Term
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Definition
| the most common form of fixed focusing |
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Term
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Definition
| This type of focusing is a result of using a curved active element. |
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Term
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Definition
| This type of focusing is a result of using a lens. |
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Term
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Definition
| This type of focusing is a result of electronic manipulation from the ultrasound machine. |
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Term
Beam diameter in the near field and focal zone narrows
Focal depth decreases
Beam diameter in the far zone increases
Focal zone is smaller |
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Definition
| What are the four results from using focusing? |
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Term
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Definition
| In this display mode, the x-axis represents depth and the y-axis represents amplitude. |
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Term
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Definition
| In this display mode, the x-axis represents depth and the z-axis represents amplitude. |
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Term
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Definition
| In this display mode, the x-axis represents time and the y-axis represents depth. |
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Term
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Definition
| The first form of grayscale imaging. |
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Term
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Definition
| the only display mode that provides information regarding reflector motion with respect to time |
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Term
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Definition
| If there are more cycles in a pulse, the numerical value of the range resolution will _________. |
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