Pulsed Echo Instrumentation Flashcards by Kacie Schrempp

highly sophisticated machine that creates and receives sound pulses to present audio and visual information for interpretation

ultrasound machine

How well did you know this?

Not at all

Perfectly

6 major components of an ultrasound machine

transducer
pulser and beam former
receiver
display
storage
master synchronizer

How well did you know this?

Not at all

Perfectly

what creates and controls the electrical signals sent to the transducer that generate sound pulses

pulser and beam former

How well did you know this?

Not at all

Perfectly

what does the pulser determine

amplitude, PRP, PRF

How well did you know this?

Not at all

Perfectly

what does the pulser do

excites the crystal and creates the sound beam

How well did you know this?

Not at all

Perfectly

does the pulser operate during transmission or reception

transmission

How well did you know this?

Not at all

Perfectly

can we adjust the pulser voltage?

yes, by changing the output power

How well did you know this?

Not at all

Perfectly

attempts to standardize output have resulted in these two measurements on modern systems

thermal and mechanical index

How well did you know this?

Not at all

Perfectly

thermal index

How well did you know this?

Not at all

Perfectly

mechanical index

How well did you know this?

Not at all

Perfectly

what determines firing delay patterns for phased array systems

beam former

How well did you know this?

Not at all

Perfectly

is the beam former part of transmission or reception

considered part of transmitter but functions during both

How well did you know this?

Not at all

Perfectly

what does the beam former do

coordinates electrical signals to optimize the sound beam being transmitted
adjusts electrical spike voltages to reduce lobe artifacts
establishes correct time delays used for dynamic receive focusing in reception
controls dynamic aperture by varying the number of PZT crystals used during reception and transmission

How well did you know this?

Not at all

Perfectly

what are the advantages of using a modern, digital beam former

has system updates, software updates, rapid product improvement, rapid development, stable (no mechanical parts to wear out), and versatile because they can use transducers of wide frequencies

How well did you know this?

Not at all

Perfectly

what is the beam former switch

a transmit/receive switch that protects receiver components from powerful signals during transmission
also directs signals from transducer to appropriate electronic processing components within the US system

How well did you know this?

Not at all

Perfectly

function of the receiver

to transform electrical signals from transducer into a form suitable for display

How well did you know this?

Not at all

Perfectly

order of operations of a receiver

amplification 
compensation
compression
demodulation
reject

How well did you know this?

Not at all

Perfectly

what is the process of improving quality of signal before it is amplified

preamplification

How well did you know this?

Not at all

Perfectly

what are the 2 parts of demodulation and their purpose

rectification - convert negative voltages to positive ones

smoothing / enveloping - smoothing line around bumps

How well did you know this?

Not at all

Perfectly

purpose of US display

to display data

storage devices

hard drive, CD, DVD, videotape, magneto-optical discs, paper printouts, photos, USB drive

what is the purpose of the master synchronizer

to maintain and organize proper timing and interaction of system components

random disturbance that reduces a signal’s clarity and contaminates an image

noise

comparison of signal to noise

signal to noise ratio

when the signal to noise ratio is high, the signal is (higher or lower) than the noise

higher

signal to noise ratio has what relationship with power

direct

what is another name for PRP

depth of view

the time between a voltage spike and the next (or time from the start of one pulse to the start of the next pulse)

PRP

can we adjust the PRP?

yes, by changing the depth | DIRECTLY related to depth

what is the number of pulses that an US system transmits per second

PRF

can we adjust the PRF?

yes, by adjusting the depth of view | INVERSELY related to depth

what is a channel made of

made of a single PZT element, beam former / pulser, and the wire connecting them

amplification

also called receiver gain, treats all signals identically amplitude brightens the entire image we CAN adjust it

compensation | TGC, DGC, swept gain

treats all signals differently based on depth because of attenuation uniformly bright, with proper compensation images become increasingly darker with depth we can adjust it

compression | log compression, dynamic range

signals treated differently based on strength changes in grayscale mapping, strong signals appear bright white we CAN adjust

demodulation

prepares electrical signals to be suitable for display | we CANNOT adjust this

reject | threshold, suppression

only weak signals affected weak echoes appear or are eliminated from image we CAN adjust

near gain

constant amount of compensation

delay

varying compensation

slope

compensation corrects for attenuation

knee

reflections are at max compensation

far gain

max compensation that receiver can provide

if a TGC curve attenuates at a shallow depth, it has a (high or low frequency)

high

dynamic frequency tuning

dampening of high frequency pulses to create a good axial resolution

ALARA

as low as reasonable achievable | used to minimize bio effects on patient

what do output power and receiver gain have in common

they both change the brightness of the entire image

output power

``` changes brightness of entire image alters signal to noise ratio alters bio effects bioeffect concerns decrease this FIRST if image is too bright ```

receiver gain

``` changes brightness of entire image does not alter signal to noise ratio no exposure no bioeffect concerns increase first if image is too dark ```