PollEv Ch. 14/15/16

Which of the following functions is included in the pulser?

Beam former

Mechanical index is closely related to the amount of ______ produced by the ultrasound system

power

Which of the following synchronizes and times functions of the ultrasound system

master synchronizer

An increase in output power will _______ the signal-to-noise ratio

increase

T or F: When scanning the fetal brain, increasing the output power is the preferred method to increase image quality and decrease bioeffects

false

Which of the following should be done in order to increase noise?

decrease pulser power

what are the receiver function

amplification, compensation, compression, demodulation, reject

Decreasing the dynamic range will result in?

fewer shades of gray

During an ultrasound examination, you notice that your image is too dark overall. What should you do first to increase the brightness of your image?

increases amplification

what is amplification also known as

receiver gain

Preamplification is the process of improving the quality of a signal before it is amplified. Where does it take place?

transducer

Adjustments from which of the following will create an image of uniform brightness from top to bottom?

swept gain

swept gain is also known as

compensation

T or F: A low signal-to-noise ratio is degrading to image quality.

true

Which of the following is a receiver function?

supression

suppression is also known as

reject

Scan converters do all of the following, except?

convert bits to pixels

All of the following are limitations of analog scan converters, except

spatial resolution

What process do modern scan converters use, that separates them from analog scan converters?

digitizing

The smallest amount of computer memory is known as a

bit

T or F: An increased pixel density will create an image with larger pixels and improved spatial resolution.

false

Low pixel density will degrade which of the following?

spatial resolution

Many bits per pixel will increase which of the following?

shades of gray and contrast resolution

How many possible shades of gray are displayed with 3 bits of memory?

8

Which of the following is a preprocessing function?

swept gain (compensation)

Coded excitation occurs in the

pulser

Coded excitation was designed within the context of

bioeffect

Read magnification is considered _______ and write magnification is considered _______

postprocessing, preprocessing

Coded excitation provides

all the above

Frequency compounding occurs in the ______ and reduces ________

receiver, speckle artifact

Edge enhancement is an image processing method used to

emphasize the sharpness of edge boundaries

With spatial compounding, which of the following is reduced

frame rates (and temporal resolution)

Spatial compounding used with a mechanical transducer can greatly reduce speckle and shadowing artifacts.

false

A sonographer is performing a duplex ultrasound exam of a common femoral vein. They are having trouble getting color to fill in the vessel. Which imaging technique would be most useful?

increase persistence

Which of the following is most useful when applied to differentiate malignant from benign lesions?

elastography

DICOM stands for

digital imaging and computers in medicine

Dynamic range is reported in units of

dB

The dynamic range of information_________the more it is processed

decreases

A signal within a systems receiver has a dynamic range of 20dB after compression. The original signal was compressed by 60dB. What is the dynamic range of the original, uncompressed signal?

80 dB

Fewer shades of gray is associated with which of the following

narrow dynamic range

A sonographer is looking at 2 ultrasound machines. On one, the dynamic range is 30dB. On the other, the dynamic range is 130dB. Which of the machines will acquire the best contrast resolution?

130 dB