Term
| What is the region from the transducer to the smallest cross-sectional area of a sound beam called? |
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Definition
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Term
| What is the point or location where a beam reaches its smallest dimension? |
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Definition
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Term
| As sound travels deeply into the far zone, the beam diverges, or spreads out. What results in a greatest beam divergence deep in the far zone? |
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Definition
| Small diameter, low frequency |
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Term
| All of the following terms describe the shape of a sound wave created by a tiny fragment of PZT except: |
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Definition
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Term
| Which of the following explains the difference in sound beam shape created by a disc-shaped crystal from that of a small chip of PZT? |
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Definition
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Term
| Huygens' principle is based on____ |
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Definition
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Term
Axial resolution is also known as all of the following except:
a. Angular
b. Longitudinal
c. Range
d. Radial
e. Depth |
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Definition
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Term
| The lateral resolution of an ultrasound system is primarily determined by the_____ |
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Definition
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Term
| Axial resolution is equal to: |
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Definition
| One-half spatial pulse length |
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Term
| The focus of an ultrasound beam is the location where the____ |
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Definition
| Optimum transverse resolution is |
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Term
When using standard ultrasonic imaging instrumentation, lateral resolution has a higher numerical value than the axial resolution.
(TRUE or FALSE) |
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Definition
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Term
| What will lower the value of an ultrasound system's lateral resolution? |
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Definition
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Term
| Which of the following transducers has the best axial resolution? |
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Definition
| 2.6 MHz & 2 cycles per pulse |
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Term
When using an instrument typical of today's imaging devices, a higher frequency transducer is likely to improve axial resolution.
(TRUE or FALSE) |
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Definition
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Term
| Two ultrasound systems are identical except for the diameter of the transducers piezoelectric crystal. Which system has the deepest focus? |
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Definition
| The one with the larger diameter crystal |
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Term
Which of the following focusing techniques is different from the others?
a.lens
b.curved crystals
c.fixed
d.phased |
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Definition
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Term
| The thing(s) that can be used to create focusing is/are |
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Definition
phasing of the voltage signals
curved elements
lens |
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Term
| All of the following occur with focusing except: |
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Definition
| lower intensity at the focus |
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Term
| Which of the following techniques is internal focusing? |
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Definition
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Term
| Which of the following techniques is external focusing? |
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Definition
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Term
| Which of these terms means adjustable focusing or multi-focusing? |
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Definition
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Term
| Which of these techniques is consistent with variable or multifocusing? |
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Definition
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Term
| Which imaging modality places dots of dissimilar grayscale on the display? |
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Definition
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Term
| Which imaging modality places time-of-flight information on the x-axis and echo amplitude on the y-axis? |
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Definition
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Term
| Which imaging mode accurately displays reflector depth? |
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Definition
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Term
| With B-mode, on which axis the strength of the reflection input? |
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Definition
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Term
| To which of the following do the x-axis of a b-mode, the y-axis of an m-mode and the x-axis of an a-mode all relate? |
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Definition
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Term
What is the only display mode that provides information regarding reflector motion with respect to time? |
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Definition
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Term
| With A-mode, what is displayed on the x-axis? |
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Definition
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Term
| Which mode provides the foundation for real-time, gray scale anatomic imaging? |
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Definition
| B-mode, or brightness mode |
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Term
| At the focal zone, the intensity is usually greater because |
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Definition
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Term
| The main factor that determines axial resolution is |
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Definition
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Term
| Lateral resolution is equal to ____. |
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Definition
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Term
| A longer near zone length can be produced by |
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Definition
| changing to a higher frequency transducer |
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Term
| The principle that says all points on a wave front are small point sources for secondary wavelets is |
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Definition
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Term
| Axial resolution is inversely related to |
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Definition
|
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Term
| Huygens' principle refers to__ |
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Definition
|
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Term
|
Definition
| is affected by wavelength |
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Term
|
Definition
| Is affected by beam diameter |
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Term
| Decreasing spatial pulse length |
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Definition
| Improves axial resolution |
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Term
| Axial resolution is improved with |
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Definition
| transducers with higher frequency |
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Term
Lateral resolution is also called |
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Definition
azimuthal, angular and transverse
(LATA) |
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Term
| Axial resolution refers to the accurate measurement of structures ________ to the beam |
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Definition
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Term
| What is the shape of the sound beam created by a tiny piece of PZT |
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Definition
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Term
A sound beam is created by a round PZT crystal with a diameter of 10 mm. The focal depth of the sound beam is 8 cm. What is the diameter of the sound beam at a depth of 16 cm?
|
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Definition
| The same as the transducer diameter |
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Term
| Which of the following transducers has the least divergence in the far field? |
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Definition
| highest frequency, largest crystal diameter |
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Term
| Which of the following transducers has the shallowest focus? |
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Definition
| lowest frequency, smallest crystal diameter |
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Term
| Which of the following determine the spread of a sound beam in the far field? |
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Definition
| diameter of ceramic and frequency of sound |
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Term
| Which of the following determine the focal length of a sound beam? |
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Definition
| diameter of ceramic and frequency of sound |
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Term
| Which of the following determines the frequency of sound created by a pulsed wave transducer? |
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Definition
| thickness and speed of sound in the ceramic |
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Term
| Which of the following has the same meaning as transducer diameter? |
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Definition
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Term
| Under which of the following conditions is axial resolution improved? |
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Definition
| decreased spatial pulse length |
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Term
| Frequency and focal depth are _____ related. |
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Definition
| Directly (directly-higher acoustic frequencies create deeper foci and lower frequency crystals produce beams with shallow foci) |
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Term
| A sonographer is performing a study on a patient and desires superior depth resolution. Which of the following changes would create such a system? |
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Definition
higher frequency
shorter wavelength
fewer cycles in a pulse
less ringing |
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Term
| A natural, unfocused beam diverges |
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Definition
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