Quality Assurance Flashcards
What is quality assurance?
A program that ensures proper and consistent operation of the imaging systems
What does QA assure? 7
- Proper equipment operation
- Detection of degradation of performance
- Minimizes machine down time
- Minimizes repeat examinations
- Sonographer and patient safety
- Cost efficiency
- Maintains standards
Who are the three main people responsible for QA?
- Physician
- Sonographer
- Service
Who is the director of the QA program?
The physician
What is the responsibility of the rad?
To assess images for overall quality
What does the sonographer do in terms of QA? 3
- Assess the image quality
- Routine testing and record keeping
- Routine maintenance, such as cleaning filters and visual inspections
Routine preventative maintenance may include what? 5
- Cleaning surfaces
- Cleaning recording devices
- Cleaning fan filters
- Assessing cable and transducer integrity
- Film/ image recording quality
What are the two types of service personnel?
- The manufacturer
- The biomedical personnel
What does the manufacture do in the QA program?
Provide routine preventative maintenance and repair equipment as needed
What does the biomedical personnel do in the quality assurance program?
Acceptance testing when a machine arrives on site to ensure patient and employee safety
What does acceptance testing involve?
Sophisticated testing done before systems are placed into operation
What is tested in acceptance testing?
Imaging performance and power output are measured and the system is checked to see that it will work with ancillary equipment in the department
What is routine testing all about?
Measuring image performance and assessing over time
When is routine testing done on a tissue equivalent phantom? And what is tested? 3
On a regular schedule a tissue phantom is used to assess things like
- Resolution
- Sensitivity
- Accuracy
A key component of a good QA program is what?
Record keeping
What is the schedule like for QA?
Always performed on a regular schedule dependent on the task
When is routine maintenance done by a sonographer?
Daily, weekly, monthly
How often does manufactures perform QA?
2-3 times per year while the machine is under warranty or a service contract
Routine testing is typically done when?
On a yearly basis
What is the AIUM 100?
An older testing device in which a plastic case contains 0.75 mm steel rods arrange din groups and filled with water, alcohol, and algaecide
What is an advantage and disadvantage of AIUM 100?
+ They are relatively inexpensive
- They have no greyscale therefore no attenuation
What is a tissue equivalent phantom?
A structure that contains one or more materials that simulate a body of tissue in its interaction with ultrasound
Phantoms consist of what? 4
- Plastic case
- Gel mixed with graphite powder
- Rod groups
- Solid and cystic lesions
What are some advantages of phantoms? 4
- Better approximation of clinical performance
- Allow for greyscale,
- Attenuation
- Speed of sound
What is an disadvantage of phantoms?
They are more expensive
The TE phantoms films are made of what?
Thin films made of saran or polyurethane
The TE phantom containers are made of what? 3
- ABS
- PVC
- Acrylic
A good phantom must have the following characteristic similar to soft tissue, what are they? 5
- Attenuation coefficient
- Speed of sound
- Backscatter coefficient/ Relative contrast
- Elasticity
- Thermal properties
Phantoms can test for what things? 6
- Dead zone measurement
- Detailed resolution
- Distance accuracy
- Image uniformity
- Depth of penetration
- Cyst imaging capabilities
What is dead zone?
The area in the near field close to the transducer
What is another name for dead zone?
Main bang
What is the size of dead zone with old mechanical probes?
It can be quite large
What is the technique for imaging dead zone pins?
Imaging the dead zone pins and observing changes over time
What is acceptable in terms of dead zone difference?
Less than 15 mm of change is acceptable over time
In terms of axial resolution the phantom can be used to test what?
Test the systems abilities to separate interfaces along the path of the beam
What is the technique for testing axial resolution?
Measuring the smallest separating visible between the axial resolution pins at various depths, and watching for changes over time
What does this test for?
Dead zone
In terms of lateral resolution how does the test for this?
The phantom can be used to test the systems ability to separate interfaces across the beam
What does this test?
Axial resolution
What is the technique required to measure lateral resolution?
Measuring the lateral resolution pins and is dependant on the depth and focus, watch for changes over time
What is tested here?
Lateral resolution
point spreading
Elevational resolution is also known as what?
Slice thickness and z axis
What is the technique to measures elevational resolution?
This one is different form others and for a quantitative assessment a different phantom is used.
What is the phantom used for elevational resolution?
A spherical void phantom or beam profile phantom will yield specific measurements
What does this test?
Elevational resolution
Both horizontal and vertical distance accuracy can be measured using what? What does this technique involve?
- Appropriate pins
- Measuring pins at known distance calliper s and comparing the numbers
In terms of distance accuracy, it is important to do what?
Measure over larger distances to detect smaller margins of error
TGC characteristic test is what kind of test?
A user specific test where the results are based on observations of the individual performing the test
When doing a TGC characteristics test, images may be captured with what?
Different slide pod configurations under different conditions and compared over time
Image uniformity tests, test what?
Linear arrays consistency along the array
What does image uniformity looks like?
Inhomogenous regions or areas of non uniforming
What test does this demonstrate?
Image uniformity
Sensitivity tests a system ability to detect what?
Weak echoes
What is a common technique for sensitivity known as?
Maximum depth of visualization
In terms of sensitivity testing, what are adjusted?
Power and gain are optimized for penetration and the observer records the depth where the brightness starts to fade
What does this test for?
Sensitivity
In terms of dynamic range, one can measure what on the machine?
The number of shades of grey displayed on the machine
What kind of test is dynamic range? What does it require?
- Subjective testing
- Good record keeping
In terms of testing dynamic range, what do we do with the images?
Images are compared over time to appreciate change in the display
What does contrast resolution measure?
The ability to distinguish between simulated lesions of similar echogenicity
Contrast resolution allows for what?
A measurement of lesion detection where the system demonstrates the ability to detect small lesions with a variety of appearances
What is the technique for contrast resolution testing?
Involves scanning, solid, cystic, echogenic, and hypoechoic lesions.
Images are compared to previous results
What is registration?
A test for older static B scanners to ensure arm positioning is accurate for the reconstruction of an image
What is the technique for registration testing?
Involves scanning pins from 3 sides to see if the lines intersect at one point
What does this demonstrate?
Registration
What are the benefits of Flow or TE tissue equivalent doppler phantoms?
They match the clinical experience but are expensive
What are string phantoms?
They move a string or belt in a water bath and do not match the clinical experience and they are more affordable
Doppler phantoms are used to measure what? 5
- Maximum depth
- Gate position accuracy
- Volume flow and velocity accuracy
- Colour flow penetration
- Image congruency test
What dose this demonstrate?
Doppler phantoms
What ares one applications of phantoms other than QA? 3
- Demonstration
- Training
- R and D
What are specialty phantoms used for? 7
- Biopsy
- Mass
- 3D
- Cryosurgery
- Brachytherapy
- HIFU
- IVUS
Some devices are used by who to do what?
They are used by service personnel or manufactures to evaluate the systems power output
What is usually included with hydrophones? 4
- Plotter
- Spectrum analyzer
- OScilloscope
- Schieren system
What are some outputs testing devices? 3
- Hydrophone
- Power (force) balancers
- Calorimeter
What is a hydrophone?
A small (1mm) transducer that produces voltage proportional to the received acoustic pressure wave.
When a hydrophone is used with a plotter it can do what?
Be moved throughout the sound field and produce a beam profile
When a hydrophone is used with a oscilloscope it can measure what? 5
- SPL
- PD
- PRP
- PRF
- DF
When a hydrophone is used with a spectrum analyzer it can measure what? 3
- Resonant âfâ
- Bandwidth
- Q factor
A force balance is used to measure what?
The acoustic power
What is a force balance apparatus? What does it determine?
A sophisticated and sensitive micro balance that is phased in the sound field and calibrated to determine acoustic power and intensity
What is this?
A hydrometer
A calorimeter is essentially what?
A heat meter used to measure acoustic power
How does calorimeters work?
An enclosed fluid container with a very sensitive thermocouple detects desperation changes and can determine acoustic power
