PHYSICS 2 EXAM 1

byte

group of eight bits of compiler memory

Images were displayed one frame at a time in a process called

static scanning

temporal resolution

retains to accuracy in time describes ability to precisely position moving structures from instant to instant

frame rate and time relationship

inverse

shallow imaging increases _____ and improves ____

frame rate; temporal resolution

deeper imaging ____ frame rate and degrades temporal resolution

decreases

imaging depth and frame rate relationship

inverse

Higher frame rates are possible when each individual image is made with _____ pulses

fewer

Lower frame rates occur when each image is made with ____ pulses.

more

pulses per frame and frame rate relationship

inverse

single focus

-one pulse per scan line

-shorter t-frame

-higher frame rate

-better temporal resolution

-poorer lateral resolution

multi focus

-many pulses per scan line

-longer Tframe

-lower frame rate

-diminished temporal resolution

-improved lateral resolution

sector size is also called ...

field of view

narrow sector

-fewer pulses per frame

-shorter Tframe

-higher frame rate

-superior temporal resolution

wide sector

-more pulses per frame

-longer Tframe

-lower frame rate

-inferior temporal resolution

Not always apparent, ultrasound systems can alter the spacing between sound beams is called ...

line density

low line density

-widely spaced lines

-fewer pulses per frame

-shorter Tframe

-higher frame rate

-high temporal resolution

-poor spatial resolution

high line density

-tightly packed lines

-more pulses per frame

-longer Tframe

-lower frame rate

-low temporal resolution

-excellent spatial resolution

ultrasound six major components

-transducer

- pulser and beam former

- receiver

-display

-storage

- master

transducer

Device that converts one form of energy to another

pulser and beam former

Pulser: determines amplitude, PRP, PRF

Beam former: determines firing delay patterns for phased array.

receiver

transforms the electrical signals from the transducer into a form suitable for display

display

presents processed data

storage

archives the ultrasound studies (storage devices - CD)

master synchronizer

maintains and organizes the proper timing and interaction of the system's components

single to noise ratio

random and persistent disturbance that obscures or reduces a signal's clarity display

when single to noise is high

the signal is much stronger than the noise and the image is of high quality

when single to noise is low

the strength of the signal is closer to the strength of the noisee

PRP is also called

Depth of view

is PRP adjustable

yes

the pulser determines the time between one voltage spike and the next is called..

Pulse repetition period

shallowing imaging

-shorter listening

-Shorter PRP

-Higher PRF

deep imaging depth

-longer listening time

- longer PRP

- lower PRF

order of receiver operations

1. amplification

2. compensation

3. compression

4. demodulation

5. reject

amplification is also called

receiver gain

each signal undergoes the ____ __ of amplification

equal amount

amplification adjustable or not

adjustable

receiver corrects for attenuation with a process called

compensation

compensation creates an image that is uniformly bright from..

top to bottom

compensation adjustable or not

adjustable

synonyms for compensation

time-gain compensation (TGC), depth gain compensation (DGC), swept gain

compression keeps images ______ content within the range of direction by the human eye

grayscale

compression adjustable or not

adjustable

demodulation

two part process that changes into a form more suitable for display on a monitor

demodulation adjustable or not

not adjustable

rejects allows sonographer to control whether ...

low level gray scale info within the data will appear on the displayed image

reject adjustable or not

adjustable

ALARA

As Low As Reasonably Achievable

bistable means

composed of only two shades black and white

The scan converter's function is to

store information coming from the receiver.

two type of scan converters

analog and digital numbers

analog numbers

real world, unlimited # of choices, continuous values

digital numbers

computer world, limited choices, discrete values

low pixel density

few pixels per inch, larger pixels, less detailed image, lower spatial resolution

high pixel density

many pixels per inch, smaller pixels, more detailed image, higher spatial resolution

binary number

group of bits and a simply a series of zeros and ones

word

computer memory consist of two bytes

equation for bits

2 ^ number of bits

example - 16 bits equal =

Word

preprocessing means

before storage

postprocessing

after storage

preprocessing

time gain compensation, log compression, write magnification, persistence, spatial compounding, edge enhancement, fill-in interpolation

post processing

any change after freeze frame, black/white inversion, read magnification, contrast variation, 3-D rendering

read magnification

uses old data, postprocessing, larger pixel size, same # of pixels as in the original ROI, unchanged spatial resolution, unchanged temporal resolution

write magnification

acquires new data, preprocessing, identical pixel size, more pixels than in the original ROI, improved spatial resolution, may improve temporal resolution

coded excitation

A sophisticated form of transmission in which the driving voltage pulses have intrapulse variations in amplitude, frequency, and/or phase.

spatial compounding

method of using sonographic information from several different imaging angles to produce a single image

frequency compounding

is an advanced technique that reduces speckle artifact and noise in ultrasound images

edge enhancement

Is an image processing method that makes pictures look sharper

temporal compounding

number of precious frames are superimposed on the most current frame creating a smoother image with noise reduction, higher signal to noise ratio and improved image quality

fill in interpolation

the programs uses known gray scale level neighboring pixels to fill in or predict the missing info (preprocessing)

PACS means

Picture Archiving and Communication System

PACS are used for

image storage

DICOM means

Digital Imaging and Communications in Medicine

DICOM are used for

networking / sharing info

dynamic range

a method of describing the extent to which a signal can vary and still maintain accuracy

compression of dynamic range example - measurements are between 30 lbs and 300 lbs what is the ratio?

10:1 (300/30)

compression of the dynamic range is necessary for the ..

system to perform to reduce inaccuracies when signal from one component to another

compression ____ dynamic range of the signal without introducing errors

reduces

the sonographer can _____ the compression

adjust

dynamic range is considered a " _____________" or number of possible shades of grayscale

number of choices

recall

narrow dynamic range means fewer shades of gray

wide dynamic range means ...

more shades of gray or low contrast