Ultrasound Physics Flashcards
What term would be used to describe a region of tissue displayed on an ultrasound image that appears to have uniform brightness?
**Homogeneous **would be used to describe an area of tissue with uniform brightness.
How does crystal diameter impact the focal zone and beam divergence?
A small diameter crystal results in a more shallow focal zone and beam diveregence INCREASES in the far zone.
In contrast,
**A larger diameter crystal results in a longer near zone (deeper focus) and there will be less beam divergence in the far zone.
What is Persistence?
Persistence is a color Doppler averaging technique in which multiple frames of color Doppler data are compounded or overlaid to improve sensitivity and display. Persistence can be used in gray scale imaging but is used more frequently and is of most concern in color Doppler imaging. Persistence can be employed to “smooth out” or “fill in” the flow within the image. Various algorithms are used. For example: Many frames of data per second are obtained. Five (5) frames are over laid or displayed at the same time. When the 6th frame is acquired and displayed, the first frame is dropped off.
How would you optimize this image?
Lower the PRF
The relatively high PRF used for the given velocity in this spectral waveform may prevent low velocity flow events from being identified.
How do we determine if our test is correct?
In order to determine whether the results of our diagnostic test are true or false, we compare with a Gold Standard exam performed on the same patient. If our results are confirmed by the gold standard, it was true result, in not, it was a false result.
Note: The gold standard is a diagnostic test that has already been clinically validated and found to have a very high degree of diagnostic accuracy. While no test is 100% accurate, for statistical purposes, the gold standard is considered to be 100% correct. The results of the diagnostic test being evaluated are compared with the results from the gold standard.
