SPI Summary

A linear scan has what type of display

Rectangular display, where it has scan lines

A “slice of pie” where scan lines originate from the same location/starting point but travels out in different directions is what type of scan

Sector scan

Sound is 2 types of waves: which are?

Mechanical & Electromagen waves

What are two types of mechanical waves?

1. Longitudinal Compressional wave

2. Transversal wave

Compression is a region of

High pressure & high density ( many particles are present on the medium)

Rarefaction is a region of

Low pressure & low density ( fewer particles are present on the medium)

What must be present if sound wants to travel?

a Medium must be present, waves only exits if theres a medium( air, body tissues)

in Longitudinal waves/ compressional waves, how does the particles move?

Moves in the same direction (parallel to the wave) ~ [ pressure variation in the sound wave causes particles of the medium to oscillate(vibrate) back & forth ]

In Transversal wave or shear waves, in what direction do particles move ?

Moves in a perpendicular direction

What are 3 Acoustic Variables that describe a sound wave ?

1. Pressure - concentration of force into area

2. Density - concentration of mass

3. Distance/ Particle Motion/ Vibration - measures distance

4. ( doesnt matter)Temperature - concentration of heat energy

What type of wave that can only go through a media is …

Mechanical

What type of wave can go through a vacuum and media

Electromagnetic

define propagation speed.

Speed of wave as it moves through Medium

Difference between PWD & CWD

1. PWD has 1 crystal & used for Imaging

2. CWD has 2 crystals & No image

Define Wavelength

Distance measurement to complete 1 cycle

Equations for Propogation speed (C)

C= F(Y) & C=B/p

Equations for wavelength (y)

Y= C/F & Y= SPL/ n

Define Density

Concentration of Matter

Stiffness

Hardness of Matter

Define Frequency

numbers of cycles something happens in a given period of time

Equations for Frqx

F= # of cycles/ time

F= 1/ T

F= C/Y

As Low As Reasonably achievable (ALARA) is used to ensure the proper equipment settings and helps minimize the exposure time; What are 3 Major factors of controls that help us safely use ultrasound in an exam?

1. Power

2. Intensity/ Amplitude

3. Time

Define whats ultrasound Imaging?

Non-Invasive way of looking inside of the human body to image anatomy which uses a pules-echo technique

Define Pulse echo technique

Pulses of U/S are generated by the TX & sent to the ptx where they produce echoes at organ tissues & the returning echoes are detected by the TX & presented on the display

In Ultrasound how many cycles are in 1 pulse ?

2/3 cycles made up of pressures called compression & rarefaction & have units of pascals (Pa) or mega-Pascals (MPa)

Whats the frequency range for Subsonic / Infrasound?

<20Hz

Whats the frequency range for Audible sound?

1. 20Hz-20,000 Hz

2. 20Hz- 20kHz

3. 20Hz × 10³Hz

Whats the frequency range for Ultrasound?

1. >20,000 Hz

2. > 20kHz

3. >20Hz × 10³ Hz

Whats the Frequency range for Ultrasound?

1. > 1,000,000 Hz

2. > 1000 kHz

3. 1MHz

4. > 10^6 Hz

If I have the frequency of Hz & I want to convert into time what would be the unit?

1/sec

If I have the frequency of KHz & i want to convert it into time what unit would it be ?

1/ms

If my frequency is in MHz & i want to convert it in time what unit would it be ?

1/ microsecond

Define Pulse repetition Frequency

number of pulses that occur in 1 sec

In pulse repetition frequency what equations are there and what units do we use?

PRF= # of pulses / time & PRF= 1/PRP

Units: Hertz, KiloHertz, MegaHertz

Define Pulse Repetition Period

Time measurement from one pulse to the next pulse

What are the equations for Pulse repetition Period and what are its units?

PrP= 1/ PRF & PRP= PD+ LT

Define Pulse duration

Time to complete 1 cycle

What are its formulas for Pulse Duration and what are its units

PD= n (x) T & PD= PRP - LT & PD=n/F

Units: secs,ms, us

Define Listening Time & what formula do we use

Machine is off & not transmitting any pulse

LT = PRP - PD

units; secs,ms,us

Define Period (T) and what formulas do we use

Time it takes to complete 1 cycle

T= 1/F & T= PD/n

Units: secs,ms, us

Define Duty factor & what formula do we use?

Percentage of time that the machine is on

DF= (PD/PRP) x 100

Units: Percentages

Define Spatial Pulse Length , & what formula do we use ?

Length or Distance measured for 1 pulse

SPL= n (x) y

Units: mm

Define bandwidth and what formulas do we use

Its a range or useful frequencies that are created in a short pulse

BW= Of / Q

Define quality factor and what formulas do we use ?

Relates to bandwidth → short pulse same as the # of cycle in that pulse

In quality factor the ______ (lower or higher) numerical value for Q factor the higher the quality of the tx.

Lower

In relation to Bandwidth, the shorter the pulse the ______ (wider/narrower) the bandwidth

Wider

If we increase stiffness what happens to the propagation speed. (Increases or decreases)

Increase

If we decrease stiffness what happens to prop speed ( decrease or increase)

Decrease

How many scan lined make up a single frame ?

96-256

The _____ of each dot corresponds to the echos ____, which in turn produced a gray scale.

Brightness ; strength

Whats it called when the ultrasound pulses goes into the tissues with a set frequency?

(Received frqx / Initial Frqx)

Initial Frqx

Whats it called when there is a pulse that returns back, once it hits the tissue & comes back?

( Received/reflected frqx / Initial Frqx)

Received Reflected Frqx

If the blood direction is TOWARDS the tx, the returning echoes that interact with this blood will have a (low/high) _____ frqx as compared yo the initial frqx, when they return to the tx from the body

Higher

If the blood flow direction is AWAY from the tx, the returning echoes that interact with this blood will have a _____ (high/ low) frqx as compared to the initial frqx when they return to the tx from the body

Lower

Whats are the formulas for Doppler shift equation?

1. FD= Fr-Fi

2. Fd= 2(Of)(V)Cos/ C

   & units are MHz

How many Doppler displays are there?

1. Color Doppler

2. PW

3. Power Doppler

4. CW

Define Attenuation

Loss of Amplitude, Intensity, & power as the sound beam travels deeper into the tissues( weakening of sound beam as it propagates through the tissues of the body)

If there is a high frqx, will attenuation be more or less?

Sound beam will attenuate more

If there is a low frqx, will attenuation be more or less?

Sound beam will attenuate less

Define Period or Time(T)

Time it takes to complete 1 cycle & each cycle is made up of 1 compression and 1 rarefraction

Increasing __________ , will have reason to be concerned with bio effects & is the reason why we should use in the ALARA( as low as reasonably achievable) principle.

Out power

(Power + Intensity + Time )

1 of the components with the ultrasound imaging system is controlling the power to the transducer. Which function is it called ?

A. Pulser

B. Transducer

C. Receiver

D. Memory

E. Display

A. Pulser

True or False: Tissue equivalent phantoms are devices made of graphite-filled aqueous gels or urethane rubber materials. Attenuation & propagation speeds in devices are similar to soft tissues

True

According to the ALARA principle, if we encounter an image which is too dark, we should increase the _______ first because it does not increase patient exposure.

Receiver Gain

Research performed within the living body of either a plant or animal is called?

A. In ViVo

B. In vitro

A. in Vivo

Research performed outside the living body and in artificial environment is called ?

In Vitro

True or False : False Positive is what we call a study performed which indicates that the patient has the disease and the test is accurate

True

True or False: True positive is what we call a study performed which indicates that the patient has the disease and the test is accurate .

True

The velocity of sound for the AIUM mm test object is ?

1,540 m/s

What helps us distinguish the different shades of grey and helps control the contrast resolution ?

Dynamic Range(dB)

What is the typical duty factor for a Continuous wav(CW)?

A. 50%

B. 70%

C. 100%

100%

Which of the following is the time it takes to complete 1 full cycle of its oscillation ?

A. Spatial Pulse Length

B. Wavelength

C. Period

Period

What uses 525 spaced lines & writes the odds first & then the evens?

Interlaced Display

Whats The relationship between between spatial pulse length & wavelength?

Direct

You’re measuring the strength of a sound wave produced by an ultrasound machine. If the sound wave increases by 9dB, approx how much has the original signal power voltage increased?

8

The range between smallest & Largest signal amplitudes received decreases with which receiver function?

Compression

Which system component adjusts the PRF appropriately for imaging depth ?

Pulser

What is the typical range of values for the pulse repetition frequency (PRF) used in real time ultrasound imaging?

1 to 10 kHz

Which terms refers to a shadowing artifact that occurs when the U/S trajectory is changed after hitting a reflector obliquely or at the boundary between 2 different media ?

Refraction Artifacts

What estimates the total output of the U/S beam by measuring the heat produced?

Calorimeter

How would you define the distance that a pulse occupies from its initiation to its completion?

Spatial Pulse Length

Which of the following most accurately characterizes the relationship between Spatial pulse length & number of cycles?

Direct

Which description most accurately characterizes the relationship between spatial pulse length & frequency ?

Inverse

Your Mechanical Index has reached 1.8 & is getting closer to the maximum allowed by the FDA.What would you do to decrease it?

Decrease the ultrasound beam output

Which formula represents pulse repetition period?

1/ PRF

Which of the following is the function of the pulser used to increase the signal to noise ratio ?

Coded Excitation

The US Food and Drug Administration mandates that the Mechanical Index be kept below what value?

1.9

What is the term used to describe the conversion of energy to heat due layers of blood moving to relative to each other?

Friction

What refers to to fluid movement that changes over time from the heart beating ?

Pulsatile Flow

What is the term used to describe the phenomenon where out of phase waves interferes with each other & result in a reduction in amplitude known as cancellation or nullification

Destructive Interference

Which display mode in U/S imaging appears as a chart of upward spikes?

A-Mode

What is the relationship between the quality factor & damping?

The higher the quality factor, the lower the damping

What are 3 major components that contribute to attenuation of an ultrasound wave as it passes through a medium?

Absorption, scattering & reflection

Section Thickness( slice thickness/ Elevational Resolution artifact)

The beam width perpendicular to the scan plane results in section thickness artifact

Which assumption is failed in section thickness & how do we fix it ?

#5 & fix it with 1.5 array tx, harmonics, virtual beam former

Speckle

an interference pattern resulting from constructive and destructive interference of echoes returning simultaneously from many scatters within the propagating ultrasound pulse at any instant ( a type of artifact has a grainy appearance )

How do we correct speckle artifact and what assumption is failed?

#6 & persistence and spatial compounding

define reverberation

Artifacts that appears on our display monitors as multiple, equally, spaced echoes, caused by the bouncing of sound wave between 2 strong reflectors positioned parallel to the U/S beam

What assumption does reverberation violates & how do we correct it?

#2( sound travels directly to a reflector and back) and correct it by Harmonics, decrease depth, decrease 2D gain, TGC, or move angle of the tx

Mirror Image

When sound reflects off a strong reflector, which acts like a mirror, a mirror image artifact is created → the sound is redirected towards a second structure, this redirection causes a replica or second copy, which is the mirror image

• artifact is placed deeper than the real anatomic structure, & always located along a straight line between the transducer & the artifact

• Artifact may appear in Color doppler