Term
| The logarithm or log of a number represents |
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Definition
| the number of 10's that are multiplied to create the original number |
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Term
| The common method of measuring the electrical signal strength and the brightness of images of sound beams is the |
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Definition
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Term
| Decibel notation does not report absolute numbers it reports |
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Definition
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Term
| Positive decibels report signals |
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Definition
| that are increasing or getting larger |
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Term
| When a wave's intensity doubles, the relative change is |
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Definition
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Term
| When a waves intensity increases 10 fold the relative change is |
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Definition
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Term
| Negative decibels describe signals that are |
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Definition
| decreasing or getting smaller |
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Term
| When the intensity is reduced to 1/2 of its original value the relative change is |
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Definition
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Term
| When the intensity is reduced to 1/10 of its original value the relative change is |
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Definition
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Term
| Sound waves decrease in intensity, power and amplitude as they propagate through the body. This is called |
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Definition
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Term
| Attenuation is determined by |
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Definition
| path length and frequency of sound |
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Term
| Distance and attenuation are related |
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Definition
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Term
| Frequency and attenuation are related |
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Definition
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Term
| Three processes contribute to attenuation |
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Definition
| reflection, scattering and absorption |
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Term
| Two forms of reflection are created in soft tissue they are |
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Definition
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Term
| Scattering is directly related to |
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Definition
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Term
| Scatter that redirects the sound wave equally in all directions is called |
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Definition
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Term
| Raleigh scattering is proportional to |
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Definition
| frequency to the 4th power |
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Term
| When frequency doubles Raleigh scattering is |
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Definition
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Term
| Organized sound back to the transducer is |
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Definition
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Term
| Disorganized reflection back to the transducer is |
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Definition
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Term
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Definition
| ultrasonic energy is converted into another energy form such as heat. |
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Term
| Attenuation coefficient is |
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Definition
| the number of decibels of attenuation that occurs when sound travels one centimeter. |
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Term
| The units of attenuation coefficient are |
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Definition
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Term
| Attenuation Coefficient in Soft Tissue |
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Definition
| the attenuation coefficient is 1/2 of the frequency |
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Term
| Half-Value Layer Thickness is |
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Definition
| the distance that sound travels in a tissue that reduces the intensity of sound to 1/2 its original value. |
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Term
| The units for half value layer are |
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Definition
| centimeters or any other unit of length |
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Term
| Typical values for half-value layer |
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Definition
| ranges from 0.25 to 1.0cm |
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Term
| The half-value layer thickness depends on two factors |
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Definition
| the medium and the frequency of sound |
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Term
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Definition
| the acoustic resistance to sound traveling in a medium |
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Term
| Impedance is calculated by |
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Definition
| multiplying the density of a medium by the speed that sound travels in the medium |
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Term
| Impedance is measured with units of |
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Definition
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Term
| In biologic media, typical values for impedance range from |
|
Definition
| 1,250,000 rayls to 1,750,000 rayls |
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Term
| Impedance is a characteristic of |
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Definition
| the medium only, it is calculated not measured |
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Term
| Acoustic impedance is also called |
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Definition
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Term
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Definition
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Term
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Definition
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Term
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Definition
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Term
| Normal incidence means that the incident sound beam strikes the boundary at |
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Definition
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Term
| Normal incidence is also called |
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Definition
| perpendicular, orthogonal, right angle or 90 degrees |
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Term
| Oblique incidence occurs when the incident sound beam strikes the boundary at |
|
Definition
| any angle other than 90 degrees |
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Term
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Definition
| the sound wave's intensity immediately before it strikes a boundary |
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Term
| Reflected intensity is the intensity of the portion of the incident sound beam that after striking a boundary |
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Definition
| returns back in the direction from which it came |
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Term
| Transmitted intensity is the intensity of the portion of the incident beam that, after striking a boundary |
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Definition
| it continues forward in the same general direction that it was traveling. |
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Term
| Intensity Reflection Coefficient is |
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Definition
| the percentage of the intensity that bounces back when a sound beam strikes the boundary between two media. |
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Term
| The intensity transmission coefficient is |
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Definition
| the percentage of ultrasound intensity that passes in the forward direction when the beam strikes an interface between two media. |
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Term
| Two principles apply to reflection with oblique incidence |
|
Definition
conservation of energy
and
reflection angle = incident angle |
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Term
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Definition
| a change in direction of wave propagation when traveling from one medium to another. |
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Term
| Refraction occurs only if two conditions are satisfied |
|
Definition
oblique incidence
and
propagation speed of the two media are different |
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Term
| Refraction is transmission with |
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Definition
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Term
| The physics of refraction are defined by what law? |
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Definition
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