Physics 3 - Quality Assurance Module 1

Patient misdiagnosis

What may result if the images we see on ultrasound are not real/accurate

D=Cxt/2

What is the range equation

1540(constant)

What is C in the range equation

Looking for gradual detonation, minimize down time of machine, minimize repeat ultrasounds

What are the main 3 goals of quality assurance

Check for deterioration over time we often don't notice when scanning everyday (mmt off, etc)

What does quality assurance check for

A program that ensures proper and consistent operation of the imaging systems

What is quality assurance (QA)

Proper equipment operation, detection of gradual degradation of performance, minimizes machine down time, minimizes repeat examinations (misdiagnosis), sonographer and patient safety, cost efficiency, maintains standards

What 7 things does quality assurance ensure

At the end of the day, US is a business and it is important it is not loosing money by deteriorating machines

Why is U/S being cost efficient important

Physician, sonographer, service (biomedical/manufacturer)

What are the 3 main people responsible for quality factor

Director

What can the physician be referred to as in terms of QA

Assess images for overall quality

What is the responsibility of the radiologist/physician

They are looking at transferred image from computer so there is a possibility any QA problems may be caused from the transfer over and not the US machine

What is the problem with the radiologist assessing the quality of images

Front line people (we are the people who may experience a problem first hand)

What can the sonographers be referred to as in terms of QA

Routine testing/record keeping and perform routine maintenance such as cleaning filters, visual inspections

What else may the sonographer do besides assessing the images

Cleaning surfaces, cleaning recording devices (more for older machines), cleaning fan filters, assessing cables & transducer integrity, film/image recording quality (PAC system)

What are some routine preventative maintenance a sonographer may do

Sometimes what you see on the machine isn't the same on the PAC system (problem with transferring)

Why is it important to film/image recording quality (PAC system)

Manufacturer and biomedical personnel

What are the 2 types of service personnel

Routine preventative maintenance and repair equipment as needed

What will the manufacturer provided

Acceptance testing when machine arrives on site to ensure patient and employees after

What is the responsibility of the biomedical personnel

Testing that the machine will work with the outlets/other machines that are already in clinic or hospital

Explain more in depth what a biomedical personnel may do

Acceptance testing

What is the sophisticated testing done before systems are placed into operation

Image performance and power out put

What are measured with acceptance testing

System is checked to see if it will work with ancillary equipment in the department

What is the main goals of acceptance testing

Measuring image performance and assessing for changes over time

Routine quality assurance testing is mainly about:

Tissue equivalent phantom

What is used to test for QA

Record keeping

What is a key component of a good QA program besides just testing the machines

Resolution, sensitivity, accuracy, etc, changes over time

What can a tissue equivalent phantom assess

Daily, weekly, or monthly

When is routine maintenance done by the sonographer

2 to 3 times per year

How often do manufacturers perform PM per year (while machine is under warranty or a service contract)

Yearly

How often is routine performance testing typically done

AIUM

What is the institute that recommends the frequency of routine performance testing

Older testing device

What is the AIUM 100

0.75mm steel rods arranged in groups filled with water, 9% alcohol and and algaecide

What is the AIUM 100 contain

Water, 9% alcohol and an algaecide

What if the mixture in the AIUM 100 consist of

0.75mm

How big are the steal rods in the AIUM 100

Inexpensive

What is the advantage of the AIUM 100

No gray scale and no attenuation (can't test for attenuation)

What is the disadvantage of AIUM 100

AIUM 100

What is this an image of

Absorption, reflection, refraction, scatter, wave-front divergence

What are the 5 different types of attenuation

Ability to differentiate between two perpendicular points

What is lateral resolution

Lateral resolution

What resolution is tested with face B and C

One or more materials that stimulate a dog os tissue in its interaction with ultrasound

What does a tissue equivalent phantom contain

Gel mixture with a graphite powder

What does the plastic case contain in the tissue phantom

Rod groups and solid and cystic "lesions"

What else do tissue phantoms

Grayscale, attenuation (TGC), and speed of sound

What else do the tissue phantoms allow to test

More expensive

What is the disadvantage of tissue phantoms

Dead zone, axial/lateral resolution, elevational resolution, depth calibration accuracy, length calibration accuracy, TGC characteristics, uniformity, system sensitivity, dynamic range, contrast resolution, lesion detection

What are the 11 things that the tissue phantoms can test

Tissue equivalent phantom

What does this image show

Tissue equivalent phantom

What does this image show

Tissue equivalent phantom

What does this image show

Saran or polyurethane

What are the films made of in tissue phantoms

Rigid and made of ABS, PVC, or acrylic

Describe the containers of tissue equivalent phantoms

Attenuation coefficient, speed of sound, backscatter coefficient/relative contrast, elasticity, thermal properties

What 5 characteristics must a good phantom have to be similar to soft tissue

5dB per cm

What is the attenuation coefficient

Temperature has an impact on the speed of the sound

Why must tissue phantoms have thermal properties

Dead zone mmt, detailed resolution, distance accuracy, image uniformity, depth of penetration, cyst imaging capabilities

What can tissue equivalent phantoms test for

Must make sure all other settings (focus, depth, gain, etc) are the exact same as the previous year

What must you make sure to do when testing the machines each year

Area in the near field close to transducer

What is the dead zone

Main bag

What is another term

Old machines

In what machines is a large dead zone seem to be quite a problem

Imaging the dead zone pins and observing change over time

Describe the technique for assessing the dead zone

<15mm of change

What is an acceptable change of dead zone over time

Dead zone

What does this image demonstrate

1/2 the SPL

What is the equation for the axial resolution

Dead zone test

What does this image demonstrate

Dead zone is getting worse

What would it mean if the next year you test for dead zone you can no longer see the pin at 1mm

Axial resolution

What resolution does this image represent

SPL = wavelength x RD

What is the equation for SPL

RD = cycle x pulse

What is the equation for ring down (RD)

Test the systems ability to separate interfaces along the path of the beam

How can the phantoms test axial resolution

Increase damping material (electric or mechanical)

How can you decrease RD

Doppler

What application requires a longer pulse and therefore less damping

Measuring the smallest separate visible between the axial resolution pins at various depths

Describe the technique for testing axial resolution

Comet tail reverberation (would cover pins under it)

Why are the axial resolution pins offset

Systems ability to separate interfaces across the beam

What is lateral resolution

Axial resolution pins

What does this image represent

Focus (beam width), frequency, aperture

What are some things that can affect lateral resolution

Lateral resolution

What does this image represent

Beam width

What is the main things that directly affects lateral resolution

Measuring the lateral resolutions that are dependant on the depth and focus, watch for changes over time

Describe the technique for testing lateral resolution

Width of the beam

How big will the object be if the beam is wider than an object

Lateral resolution

What resolution is this image testing

Pins in this image are all the same size but appear different due to different beam widths

Explain why the pins in these images are different size

Point spreading

What is it called when an object shows up the size of the beam because it is smaller than the beam

Beam is swept across

Explain why point spreading occurs

Change focus to different depths to fully test lateral resolution at multiple depths

What else should you do when testing lateral resolution

Slice thickness

What is another term for elevational resolution

Z axis

What axis is being testing when assessing the elevational resolution

False

T/F: you can use the same tissue phantoms for elevational resolution that you use for axial/lateral resolution

Spherical void phantom or beam profile phantom

What is phantom is used to test elevational resolution

Expensive/ another phantom you have to pay for

What is a disadvantage of the spherical void phantom

Qualitative assessment using more common phantom (tissue equivalent)

How else can you assess for elevational resolution without the specific phantom

Using the cystic structures in the phantoms, if the focus is at the cysts and there are still echoes in them we can infer the elevation resolution is off because the lateral resolution is the best at the focus

Explain how we can use tissue phantoms to test elevational resolution

Elevational resolution

What resolution is this image testing

Move probe down ramp to test different depths of elevational resolution (it will be better at some spots because of natural beam shape)

Explain how to use the tool in the image for elevational resolution

Horizontal and vertical

What two types of distance accuracy do we test

Measuring pins at a know distance with callipers and comparing the numbers

Describe the technique of testing distance accuracy

Measure larger distance to detect smaller margins at error (a mmt of 1cm may be close but may be totally off at a mmt of 5cm)

What should you make sure to do when testing distance accuracy

True

T/F: TGC characteristic test is a user specific test

Observations of the individual performing the test

What are the result to a TGC characteristics test based on