Physics QA Flashcards
Who directs the QA program?
Physician
Who assesses quality of images?
Radiologist
Who are the 2 types of service personnel?
Manufacturer and biomedical personnel
What does the manufacturer do?
Preventative maintenance and repair equipment
What does the biomedical personnel do?
Acceptance testing when machine arrives on site to ensure safety.
What is acceptance testing?
Sophisticated testing before machines are operated.
What can a phantom assess?
Resolution, sensitivity, accuracy, etc
What is the key component to a good QA program?
Record keeping
How many times are is the accuracy checked in a year?
2-3 times under warrranty.
What is the AIUM 100?
Older testing device, encased in plastic case that contains 0.75mm steel rods arranged in groups and filled with water, 9% alcohol and algaecide
Why are AIUM 100’s not used?
No greyscale and do not attenuate.
What are the films made of on the tissue phantoms?
Saran or polyurethane
What are the containers made of?
ABS, PVC or acrylic
How is a “good” phantom characterized?
Attenuation coefficient, speed of sound, back scatter coefficient, elasticity, thermal properties
What can phantoms test?
Dead zone, detailed res, distance accuracy, image uniformity, depth of pen, cyst imaging capabilities
Describe the dead zone
Area in near field close to transducer (AKA: main bang)
What is an acceptable dead zone measurement?
15mm
When can the dead zone be very larger?
Old mechanical probes
Ability to separate interfaces along the path of the beam?
Testing axial resolution
Ability to separate interfaces across the beam?
Testing lateral resolution - measuring pins
What is lateral res dependant on?
Depth and focus
What test requires a different type of phantom?
Elevation resolution/slice thickness
What kind of phantom is used for elevational testing?
Spherical void phantom or beam profile phantom
Is elevational resolution qualitative or quantitative?
Quantitative
How can we detect margins of error?
Measure over larger distances to detect small errors
What does it mean when we see a dark vertical band?
Usually a broken crystal
What does sensitivity test?
Ability to detect weak echoes
- increase depth until it darkens
What is dynamic range?
Number of shades of grey (contrast)
How can we determine capability of dynamic range?
Compare images over time/ compare to previous records
Contrast resolution
Ability to distinguish between simulated lesions of similar echogenicity
What does contrast res detect?
Difference in appearances of solid, cystic, echogenic, hypoechoic lesions
When is registration tested?
Tested on older static B scanners to ensure arm positioning is accurate to reconstruct an image
What does registration look like?
Scanning pins from 3 different sides to see if lines intersect at one point
What are the different types of Doppler phantoms?
Flow & String/belt
What is a flow Doppler phantom?
Match clinical experience - expensive
What are string phantoms?
Move string or belt in water belt and are affordable
What do flow phantoms measure?
Max depth Gate position accuracy Volume flow & velocity accuracy Colour flow penetration Image congruency test
What else can phantoms be used for?
Demonstration, training, research & development
Hydrophone
Measure aspects of our beam technical parameters
Produces a voltage proportional to received acoustic pressure wave
Output testing devices
Hydrophone, power balances, calorimeter
What can a hydrophone measure with an oscilloscope?
SPL PD PRP PRF DF
What can a hydrophone measure with a spectrum analyzer?
Resonant (f), bandwidth, Q factor
What does a force balance measure?
Acoustic power
Calorimeter
“Heat meter” used to measure acoustic power (thermocouple)
- amount of heat produced determines power that is being produced
What is being tested when scanning in axial resolution?
Reverberation
What is added to a hydrophone to measure fractional bandwidth?
Spectrum analyzer
What is considered a “good” tissue equivalent phantom?
One half the frequency times the path length
Who is responsible for semi-annual maintenance?
Manufacturer
What uses a sound absorbing block and sophisticated scale to measure acoustic power and intensity?
Force balance
What test is performed with a Doppler phantom ensure that colour flow is displayed accurately on the screen?
Image congruency
What is the AIUM 100 test object used to assess?
Dead zone
What is the systems best axial resolution based on?
Greatest separation between pins (2mm)
Who is the leader to carry out QA performance testing?
Radiologist & sonographer
Role of manufacturer
Routine preventative maintenance and repair
Role of biomedical personnel
Acceptance testing
How are pins configured in phantoms?
“J” configuration - compensates for reverb artifact
What group of pins is used to assess the lateral resolution?
Vertical group - will show beam width related to point spreading at various depths
