Physics chp 3 test

. What is M-Mode scanning? When is it often used? Is its temporal resolution better or worse than 2-D imaging?

. What is M-Mode scanning? When is it often used? Is its temporal resolution better or worse than 2-D imaging?

What is panoramic imaging

Image field is widened

What is spatial compounding? Is this a pre-processing or post-processing feature? What type of resolution improved by doing this? What type is sacrificed

It is a preprocessing. Multiple beams through same structure at different angles. Will slow down frame rate.

. What does the machine do to reduce these enormous ranges into something smaller that it can handle? In which part of the instrument is this done

It uses compression. Done in the signal processor.

. is edge enhancement What? Is this a pre-processing or post-processing feature

It's a preprocessing feature. Makes boundaries between textures more defined.

. What is B-Flow? Is it a pre-processing or post-processing feature? What is it used

It's a preprocessingused for scanning deep, tortious vessels, such as distal ICA

What do you call an image whose pixels are defined by 1 bit? What would it look like?

Its called bistable and will only have shades of black and white.

. What is B-Color? Is it a pre-processing or post-processing feature

Its post processing, used to enhance contrast appearance.

. What is pixel interpolation

Machine will fill gaps between two lines. Will make images appear clearer

What does frame rate mean, and what is considered a good one

Number of frames per second. 25-30 frames per second.

. What does PACS stand for? What is its purpose

Picture archiving and sharing system. File sharing used by doctors

What is A-Mode scanning? When is it often used

Used to display a single line in a different way. Usually only used on the eye.

The pulser, among other things, sets the pulse repetition frequency (P.R.F.). What do you, as an operator, do to make the pulser change P.R.F.? Is this a direct or reciprocal relationship? How is P.R.P. affected

We can change the depth. Its an inverse relationship. Prp is a direct relationship.

What is the difference between write and read zoom? Which one is a pre-processing feature, and which one is a post-processing feature

Write zone number of pixels greater than ROI and cannot be used on frozen images Read zoom is a stored image that is no longer live.

. The scan converter, image memory, and post-processing are all parts of the

image processor____ ______.

Which type of resolution is directly related to frame rate? List 6 ways to increase frame rate in 2-D imaging, and briefly explain why each works.

temporal resolution. Reduces number of scan lines decreases line density, decrease depth shortens scan lines, use write zoom decreases overall line density, decrease sector width, decrease line density, decrease number of focal zones, and decrease persistence.

Pulse delays are necessary for what two transducer functions

For electronic steering and electronic focus.

1. Put the following components of an ultrasound machine in order of their function:

1) pulser A. demodulation 2) amplifier B. amplifier 3) acc C. post-processing 4) summer D. scan converter 5) demodulation E. pulser 6) scan converter F. summer 7) post processing G. D.A.C. 8) dac H. A.D.C.

. How many shades of grey can the human eye normally differentiate

100

How many bits are in one byte? In one megabyte

8 bits are equal to one byte. 1 megabyte is 1000 kilobytes. 8 million bits in one megabyte.

What is the difference between 3-D and 4-D imaging

? is rendered by computer, never a live image. 4D is the ability to see 3D live.

What is persistence? What is its advantage? What is its disadvantage

Averages several frames into one. Reduces random noises. Temporal resolution will be decreased.

called C.R.T.,

Cathode ray tubes

. Which type of resolution are we discussing if we are interested in how many different shades of gray are available? If there are more shades, does this increase or decrease this resolution?

Contrast resolution

. What is another common name for demodulation? What are the 2 steps involved in demodulation

Detection. The two steps are rectification and smoothing also called enveloping.

. If we know the P.R.F. and the number of scan lines per frame, how can we calculate frame rate (give the formula)?

FR= prf/ lpf x 1000

. What is 2-D, or grayscale mapping? Is this a pre-processing or post-processing feature

Post processing. Changes contrast appearance by altering how grey scale looks on the monitor.

ne is responsi19. Which function of the machi ble for putting all of the scan line data together in preparation for frame (image) production? Where in the instrument does this happen? Scan converter happens in the image processor.

Scan converter happens in the image processor.

Which part of the beam former is responsible for putting together all the echo data from each pulse and preparing the scan line

The summer or the adder

Which part of the beam former keeps the pulses (to be sent away from the transducer) from being "heard" by the transducer and sent back to the machine

The transmit/ receive switch

What determines the number of possible shades of grey each pixel can be? How is this calculated?

This is determined by the number of pixels. Raise 2 to the number of bits.

If our fundamental operating frequency is 5 MHz, but we tell the machine to accept only echoes in the 9-11 MHz bandwidth, what type of filter are we using

Tissue harmonic imaging

What is the main difference between transmit power and gain

Transmit power strength of the beam. Gain amplifies the echoes.

The process of eliminating unwanted background noise by only accepting echoes whose frequencies fall within the designated bandwidth is called bandpass________ filter, or rejection________. This is done in which part of the instrument? Signal processor

bandpass rejection, signal processor

10. Coded excitation works by creating longer than normal pulses made up of sequences of cycles and partial cycles. These sequences are called coded pulses, or barker________ codes. When they come back as echoes, the machine passes them through _matched filter______ _______ and simplifies them into short pulses with higher _amplitude_________ than a simple pulse would have given. This results in a reduction of __background noise_______ _________, or improved "signal-to-noise" ratio.

barker_matched filter,amplitude and background noise

The pulser, channels, and summer are all parts of the

beam former___

12. Data that is in numerical or code form for a computer is called _digital______, while live streams of waveforms (electrical or sound) is called _analog______ data. 13. Which part of the beam former is responsible for putting together all the echo data from each pulse and preparing the scan line? The summer or the adder.

digital, analog, summer or adder

. The number of scan lines per image is known as _line density_____ ______. Having a higher number of scan lines improves what type of resolution? What is the disadvantage of this? Why? This type of resolution is called- lateral resolution. Disadvantage will slow down frame rate

line density, called lateral resolution, and will slow the machine down,

What does "pixel matrix" mean? In ultrasound, what is the pixel matrix, typically?

number of pixels stored in memory. Normally 262 or 144. 512 x 512

types of output devices (besides monitors). Which ones are digital, and which are analog? With which type can you make repeated duplications with no loss of quality

output, cd, dvd, digital files or pacs. Analog output- thermal printers, vcr, digital copied without quality.

Generally, anything which needs to be adjusted before the image is frozen and recorded in memory is called _preprocessing_________, while anything that can be done to a frozen image after it's been recorded is called _postprocessing_________.

post processing and preprocessing

. Filtering, demodulation, and compression are all part of the

signal processor