QA & Phantoms & Elastography Flashcards
Acoustic Power Measurements
A specialized ultrasound transducer referred to as a _________ is placed in the water tank and aligned to the beam to make the various intensity measurements.
hydrophone
What type of hydrophone is this?
“membrane” hydrophone
membrane hydrophones are the gold standard for pulsed wave imaging applications that require a flat response over a broad bandwidth. Flat response over a broad bandwidth. High Sensitivity
What type of hydrophone is this?
The four hydrophones pictured above are called “needle” hydrophones
needle piezoceramic hydrophones are excellent sensors for laboratory use in ultrasonic field mapping, with pinpoint access and good spatial resolution. They exhibit high sensitivity, with decreased sensitivity flatness and slightly narrower directivity.
What is Schlieren Image?
Schlieren imaging is a method to visualize density variations in transparent media.[
Visualization of pressure field produced by ultrasound
The term “schlieren imaging” is commonly used as a synonym for schlieren photography, though this article particularly treats visualization of the pressure field produced by ultrasonic transducers, generally in water or tissue-mimicking media.
QA
Many devices have been created to test system performance. System tests are designed to…..
make certain that there has been no degradation in system performance over time.
QA
What are the 2 categories to test QA devices?
- Used to test instrument operation/performance (diagnostic functionality and the entire US system)
- Used to measure acoustic output (bioeffects and safety & beam former and TDR
The 2 most commonly used hydrophones for diagnostic US TDR testing are:
- needle hydrophone
- membrane hydrophone
important parameters of hydrophones are:
- bandwidth
- sensitivity
- directivity
- flatness of response
What is TE (tissue equivalent) Doppler Phantom?
- used for Doppler
- May contain circulation pump, vibrating strings, moving belt.
- Simulates blood flow through vessels embedded in phantom.
- Used to assess Pulsed Wave, Continuous Wave, Color, and Power Doppler.
Doppler testing presents extraordinary challenges since mimicking the properties of blood in a consistent fashion is extremely difficult. As a result, many different types of Doppler phantoms have been created. The most notable are (3):
- Flow phantoms
- String phantoms
- Vibrating Plate (sensitivity) phantoms
Doppler flow phantom can be used for:
- Directional Discrimination
- Flow velocity
- Sensitivity (varying depth)
- Maximum penetration
- Location of flow
Flow Phantom Controller
What does this phantom do?
detects the maximum velocity and the direction of flow
This device is used to produce the fluid flow and can be used in conjunction with flow phantoms such as the discrimination device shown in the previous slide.
The greatest difficulty with Doppler flow phantoms is producing a fluid with stable reflective properties over long periods of time. Some companies have recognized this problem and now sell __________
blood mimicking fluids
Flow Phantom (Calibrated Flow VolumeFlow Phantom )
This flow phantom produces a known volumetric flow with laminar flow profiles in the center stream of the flow conduit.
A second Doppler sensitivity phantom can be included within the box. The sensitivity phantom has a diving vessel with a variable speed constant velocity flow
String Phantoms
A string phantom uses controlled movement of a string via a motor to create reproducible velocities.
measure velocity within the vessel
String Phantoms
Notice in the upper left hand corner the velocity profile created by the moving string. This type of phantom was designed to test:
- peak velocity accuracy
- gate depth accuracy
- spectral broadening
This phantom creates a Doppler signal by phase modulation of the ultrasound beam through very small vibrations of a target plate
Vibrating Plate Doppler Phantom
Other Test Objects
Beam Profile/Slice Thickness
- contains thin, scattering layer in echo-free material
- Used to show beam width on scan plane or section thickness
- Evaluates elevational resolution (may diminish spatial resolution and reduce visibility of small lesions if too thick).
The purpose of using phantoms
Many phantoms have been created to test various aspects of 2-D and now 3-D imaging characteristics and the various types of resolution. Some of the aspects that can be tested with these phantoms include:
Whan can we test with phantom?
- Detail resolution (lateral, axial, and elevation)
- Sensitivity
- Contrast resolution
- The dead zone (area close to the transducer dominated by reverberation)
- Dimensional measurement accuracy (depth, diameter, area, volume, etc.)
What can be tested from this?
By placing the transducer on an alternate “face” of the same phantom, different aspects of detail resolution can be tested
The multi-purpose tissue cyst phantom can be used to test many different aspects of the ultrasound system including:
- Dead Zone
- Detail resolution (lateral and axial)
- Depth accuracy
- Measurement accuracy
- Contrast resolution
- Penetration
What is this phantom and its characteristics?
AIUM 100mm Test Object is used to evaluate:
- Axial resolution – pins parallel to beam axis
- Lateral resolution – pins perpendicular to beam axis
- Electronic Caliper accuracy – measured distances between reflectors are compared to known distances on test object
- Dead Zone – pins at top of test object, close to TDR
*This phantom can be used for testing detail resolution (lateral/axial), depth accuracy, the dead zone, measurement accuracy and penetration.
Match the following group of wires with its function for the AIUM test object (Fig. 1–51)
11. registration or B-mode alignment _____
12. axial resolution _______
13. lateral resolution _______
14. dead zone _______
15. depth calibration _______
11. (A, B, C, D, E) All rods must be used to check registration accuracy
12. (A)
13. (B)
14. (D)
15. (C or E) See Fig. 1–24 and Table 1–3, Study Guide
AIUM 100 mm test object is filled with
algae inhibitor, alcohol, and water = ps 1540 m/s
scan face A, evaluate center rods, group a
scan B, evaluate rod group b
7 vertical rods separated 25, 20, 15, 10, 5 and 3 mm, top to bottom
lateral resolution
spacing of 2 closest rods seen separately
lateral resolution
scan face A, evaluate rod group d
6 vertical rods separated 20 mm from top
depth calibration accuracy
depth calibration accuracy measures the
distance between 1st and last rod
depth calibration true distance
100 mm
depth calibration, +/- _____ = call service
2mm
scan face A, evaluate rod group e
system sensitivity a measure of
the weakest echo signal that can be seen on the image display
system sensitivity, any change of _____ or more = call service
6 dB
scan face A, evaluate rod group c
5 rods separated by 10, 8, 6, 4, and 2 mm from top of test object
dead zone
distance from TDR face to first rod image
dead zone
tissue mimicking phantom AKA
tissue equivalent phantom
What is TE phantom used for?
With tissue-mimicking material the phantom can also be used for penetration tests, since this material has attenuation properties similar to tissue.
TE Phantom
Contain materials with properties similar to soft tissue such as (4 properties):
- speed of sound = 1540 m/s
- attenuation
- scattering
- echogenicity
TE Phantom
material
graphite-filled aqueous gels and urethane rubber
TE Phantom
contains
- structures that mimic cysts, and solid masses
- thin nylon lines/rods to test resolution and distance
TE Phantom
used to
evaluate grayscale
ATS Multipurpose Phantom
This phantom can be used for:
- Dead zone (ring down)
- Vertical measurement accuracy
- Horizontal measurement accuracy
- Sensitivity/Penetration
- Focal Zone
- Axial and Lateral Resolution
- Image uniformity
- Gray scale & displayed dynamic range
Curved Linear Image of the ATS Multipurpose Phantom
TE phantoms simulate tissue properties, allowing assessment of (4)
- detail and contrast resolution
- penetration
- dynamic range
- TGC
TE phantom does not assess
beam width
phantom set up _____ MHz or higher
3.5
Doppler phantom accurately evaluates (4)
- PW
- CW
- CFD
- power Doppler
beam profiler/slice thickness info gives
3D reflection amplitude info
CIRS Model 040 Phantom
Image uniformity
Axial and Lateral resolution Depth calibration
Dead zone (ring down) Registration within two different
backgrounds of 0.5 and 0.7 dB/cm/MHz
CIRS Fetal Phantom
Interventional Arterial Phantoms
The ultrasound catheter is placed in the center hole so as to image the surrounding cavities or rods of varying acoustic contrast.
ONDA HIFU Phantom (Clear Phantom Gels)
HIFU (High Intensity Focused Ultrasound) imaging intentionally produces high intensities so as to cause bioeffect lesions. These clear gel phantoms produce lesions of the same position, size, and shape as those produced in real tissue
CIRS Model 49 Elastography QA Phantom
Targets have known stiffness relative background material and vary in stiffness, diameter, and depth. These targets can be used to test elstography imaging and measurements
QA Devices for Acoustic Output
Used to measure _______ produced by ultrasound system.
amount of power (sound energy)
QA Devices for Acoustic Output
Assessment of ____________
Beam Former and Transducer
QA Devices for Acoustic Output
Types
Hydrophones
Calorimeter
Schlieren Device
Liquid Crystals
Thermocouple
Hydrophone = microprobe
- Small transducer that contains oscilloscope.
- Placed in specific locations along ultrasound beam. (Can determine beam shape.)
- Pressure from sound beam creates a voltage in hydrophone that is recorded on oscilloscope.
- Recorded voltages show period, PRP, PRF, and pulse duration.
- Calibrated hydrophones show intensities and other output measures.
Acousto-Optics – Schlieren Device
- Interaction of sound and light causes shadows that represent waves.
- A way to visualize ultrasound beam as it interacts in a medium.
- Can detect strong clusters of waves that are outside of the main beam axis.
- Indicates possibility of increased artifacts due to improper ultrasound beam generation.
*measure anything outside of the beam
Output Measured by Absorption
3 devices:
- Calorimeter
- Thermocouple
- Liquid Crystals
Calorimeter
- Measures total power through absorption.
- Soundbeam directed into calorimeter.
- Sound is converted to heat.
- Total power is calculated from rise in temp. and time of heating.
Thermocouple
- Measures power at particular location along beam axis.
- A small thermometer coated with absorbing material.
- Inserted in ultrasound beam and temperature is measured.
Liquid Crystals
- Measure general strength and shape of ultrasound beam.
- Liquid crystals change color when heated.
- Sound beam strikes crystal and heat is absorbed.
Static Elastography
- Tissue is compressed by ultrasound TDR or by internal movement of vessel pulsating or respiration.
- Images are taken pre- and post-compression to monitor tissue responses to pressure
- Movement of tissue in response to compression is calculated
- Strain (rate of tissue displacement) is calculated and assigned color that represent stiffness (soft = more strain or displacement)
- most used elastography
Dynamic Elastography
- Vibration is applied by external vibrator
- Several vibration waves are tracked as they travel in tissue
Transient Elastography
Singe vibration is sent and tracked as it travels.
Elastogram Appearance
2D Sonogram
Always used for comparison (usually in dual screen mode)
Elastogram Appearance
Grayscale Elastograms
Soft tissues = brighter
Hard tissues = darker
Elastogram Appearance
Color Elastograms
Blue = stiff, red = hard (can be inverted or system dependent)
May provide limited views of internal components of lesions
Elastogram Appearance
Color Elastograms
Blue = stiff, red = hard (can be inverted or system dependent)
May provide limited views of internal components of lesions
Clinical Uses of Elastography
most commonly used for….
Distinguishing Breast Masses
Clinical Uses of Elastography
other applications
Breast Elastography
Porelastography
the latest one
What is HIFU?
High Intensity Focused Ultrasound (HIFU)
Which type of elastography tracks fluid motion in response to external compression?
Porelastography
Which statement is not true regarding focused ultrasound?
- it uses pulses to decrease thermal bioeffects
- it may be used under MRI guidance
- it is used under ultrasound guidance
- it may be used for focal drug delivery
1
Which of the following is the ultrasound system’s ability to detect weak echo signals?
sensitivity
A quality assurance device that is used to check for clusters of sound waves located outside the main ultrasound beam axis is a good description of which type of equipment?
Schlieren Device
Which is not currently an approved clinical application for focused ultrasound?
- liver carcinoma
- fibroid tumors
- prostate cancer
- breast cancer
4
Which transducer will be expected to produce the highest measured absorption?
- 5MHz
- 7MHz
- 3MHz
- 12MHz
4
What term describes the type of ultrasound used to produce a biomechanical deformation of specific tissue for treatment of certain masses?
HIFU (high intensity focused ultrasound)
Which of the following ultrasound system components are tested for acoustic output in a quality assurance program?
- Receiver
- Transducer
- Digital Scan Converter
- Grayscale Compression
2
What is the most widely used method of tissue stiffness imaging?
- Static elastography
- Strain gauge elastography
- Magnetic Resonance elastography
- Porelastography
1
Which characteristic is typically NOT assessed using a Doppler phantom?
- Accuracy of sample volume location
- Depth capability of the beam
- Subtle echotexture changes
- Flow direction
3
Which statement is true of the Schlieren Device used to test ultrasound equipment?
- It produces image artifacts
- visualize ultrasound beam as it interacts in a medium
- It detects rates of absorption
- It charts detected output power
2
Which statement is true of grayscale elastography?
- cancers are usually soft and appear as white structures
- cancers are usually stiff and appear as dark structures
- cancers cannot be characterized using grayscale
- cancers usually have the same stiffness as surrounding tissue
2
Which test object evaluates the elevation resolution of the sound beam imaging plane?
- AIUM test object
- Doppler test phantom
- Slice-thickness phantom
- Tissue-equivalent phantom
3
When considering focal drug delivery using focused ultrasound methods, which condition would need to be met?
- use of low MI to attract the drug containing microbubbles
- use of high MI to attract the drug containing microbubbles
- use of high MI to burst the drug containing microbubbles
- use of low MI to burst the drug containing microbubbles
3
Which statement is true of quality assurance testing for acoustic output?
- Acoustic output testing is usually performed by sonographers
- Acoustic output testing usually performed by the manager
- Acoustic output testing is usually performed by the equipment manufacturer
- Acoustic output testing usually involves the AIUM 100mm Test Object
3
If the microbubbles in a contrast enhanced ultrasound burst during an exam, what effect is shown on the image display?
- Mid level grayscale representing blood flow
- Very bright echoes representing blood flow
- Grayscale tissue will display without blood flow
- Shadowing from increased reflectivity due to large acoustic impedance mismatch
4
What is considered to be a benefit of conventional tissue harmonic imaging?
- decreased clutter artifacts
- increased beam aberration
- degradation in axial resolution
- less penetration in the far field
1
What occurs when a sonographer images using tissue harmonics?
- The fundamental frequency is filtered out
- The fundamental beam’s frequency is increased
- The harmonic signal is filtered out
- There are more artifacts produced
1
What causes harmonic signal generation in tissue?
- non-linear sound wave propagation
- propagation at the fundamental frequency
- linear sound wave propagation
- propagation at the transmitted frequency
Correct!
1
By approximately how many decibels does a contrast agent increase the signal of blood?
- 10 dB
- 30 dB
- 5 dB
- 20 dB
2
If the fundamental frequency is 1.8 MHz, what is the secondary harmonic frequency?
3.6 MHz
What problem does pulse inversion harmonics overcome as compared to standard tissue harmonics?
poor axial resolution
Which statement is not true regarding harmonics?
- harmonic generation improves lateral resolution
- harmonic generation is very nonlinear
- harmonic generation is not very dependent on the focus
- harmonic generation is weaker in the immediate near field
3
Which of the following is NOT an advantage to using harmonics during imaging?
- decreases the amount of noise artifact
- improves lateral resolution
- improves axial resolution
- decreases the amount of grating lobes
3
The use of contrast media in the body will result in which change?
- doubling of signal amplitude
- increase in scattering
- doubled amount of scatter
- decreased scattering
2
all of the following measure output power from absorption EXCEPT:
- thermocouple
- hydrophone
- calorimeter
- liquid crystal
2
hydrophone measures intensity
Which characteristic is typically NOT assessed using a Doppler phantom?
- depth capability of the beam
- subtle echotexture change
- flow direction
- accuracy of sample volume location
2
Which of the following is not a clinical for elastography?
- atherosclerotic plaque
- dermatology
- transplant evaluation
- focal drug delivery
4
for HIFU
A small thermometer that measures the temperature of an ultrasound beam is a good description of which testing device?
- calorimeter
- hydrophone
- thermocouple
- Schlieren device
3
Which statement is not true regarding harmonics?
- harmonic generation is weaker in the immediate near field
- harmonic generation is very non-linear
- harmonic generation is not very dependent on the focus
- harmonic generation improves lateral resolution
3
When are signals used in tissue harmonics during produced?
- during reflection
- during refraction
- during transmission
- during attenuation
3
String objects are used to evaluate
Doppler accuracy
Which best describes the effects of damaged transducer elements in the b mode
Dark ventricular bands beginning at the top of the image
What can you test with a doppler flow patttern
Range gate accuracy
Spectral doppler velocity accuracy
Color doppler penetration
In an ultrasound phantom, the targets typically used for measuring axial resolution are:
A: Multiple round fluid-filled structures
B: Multiple round Hyperechoic simulated lesions
C: Multiple equidistant rods
D: Closely spaced targets of varying distances
E: Long fluid-filled tubes
Closely spaced targets of varying distances
Measuring the lateral width of a target on an ultrasound phantom is most closely related to:
A: Lateral resolution
B: Contrast resolution
C: Elevational resolution
D: Axial resolution
E: Temporal resolution
A
When you measure the width of a point target in a tissue mimicking phantom, you are evaluating
lateral resolution
While performing a sonogram, to minimize risk to the fetus, which imaging mode trade off would be most applicable
Use m mode instead of pulsed wave doppler to measure the fetal heart rate
Nosocomial infection is defined as one that is
Hospital acquired
Which intensity descriptor has the lowest numerical value for the characterization of a pulsed wave ultrasonic field
SATA
What should you limit when the thermal index exceeds 1
exposure time
The thermal index includes
Estimated maximum temperature increase in tissue
Which operator control most directly adjust the intensity of the transmitted pulse
Acoustic output power
Which of the following would show the highest intensity value
SPTP
Which intensity parameter is not applicable for continuous wave ultrasound
SPPA and SAPA
Which has the highest SPTA value
PW
What sonograph applicatioN has the lowest FDA approved SPTA values
Ophthalmic
What is HITU?
high intensity therapeutic ultrasound (HITU) has re-emerged as a minimally-invasive and non-ionizing therapeutic modality for the treatment of a variety of diseased tissues, including uterine fibroid, prostate, breast, and brain
What is MRgFUS ?
Magnetic resonance-guided focused ultrasound (MRgFUS) is a non-invasive treatment that combines two technologies, focused ultrasound and magnetic resonance imaging. The ultrasound beam penetrates through the soft tissues and, using MRI for guidance and monitoring, the beam can be focused on targeted sites.
US lab accreditation requires analysis of any sonographer practice. Physician practice must go through their own accreditation process. T or F ?
F
Why TI higher than using a high frequency linear array TDR than when using a low frequency curvelinear array TDR?
increased tissue absorption of energy
*TIS setting for during 1st trimester OB
During the lab we obtained measurements of different phantoms and recorded their measurements for future purpose. What was the purpose of this lab?
Check the degradation of US machine
Briefly describe the relationship between frequency and MI
inverse relationship
*note: MI is the highest during rarefaction (the lowest pressure)
using higher frequency TDR increases TI and patient’s exposure due to attenuation
Provide 3 reasons why a clinical lab may wish to apply for formal accreditation
Which combination of factor will result in their higher TI for an ultrasound system?
- 12 MHz 4cm depth
- 9 MHz 2cm
- 6 MHz 5 cm
- 3 MHz 10 cm
1
Which adjustment would result in a decrease in MI ?
increase TDR frequency
*higher frequency = higher amplitude = higher pressure = less risk of MI
Which statement is true of the lab accreditation for clinical ultrasound process?
requires supporting documents and application fee
Briefly explain the difference between education requirement for CCI certification and the education requirement for ARRT certification.
CCI - requires high school diploma/GED + clinical hours
ARRT - requires associate degree
Which one of them are credential agency for sonographers?
Which ultrasound presets carries the lowest risk of thermal bioeffects?
abdominal
