Ch 22: Quality Assurance Flashcards
This is the routine periodic evaluation of an u/s system to guarantee optimal image quality.
quality assurance (QA)
QA evals must be performed how often?
periodically and routinely
Four requirements for a QA program are:
- __ of system components
- repairs
- __ maintenance
- __ keeping
assessment, preventive, record
Five goals of a QA program are:
- guarantee proper system __
- detect gradual __
- minimize __
- reduce the # of __ exams
- reduce the # of __ scans
operation, changes, downtime, non-diagnostic, repeat
Three kinds of QA phantoms:
- tissue equivalent
- Doppler
- beam profile/slice thickness
Proper methods for a QA program are:
- test under __ conditions
- use __ instrument settings
- use a phantom with __
- image in an __
defined, constant, measurable characteristics, identical environment
T/F? Subjective information is factual and repeatable.
FALSE, objective
T/F? A subjective statement is influenced by a person’s experience and beliefs.
true
QA programs should be base on (objective/subjective) standards.
objective
This kind of phantom is used to evaluate gray scale and tissue texture.
tissue equivalent
In what ways is a tissue equivalent phantom similar to soft tissue?
- speed of sound
- attenuation
- scattering characteristics
- echogenicity
This kind of phantom is used to evaluate Doppler systems.
Doppler phantom
This kind of phantom includes a circulation pump which propels fluid through ‘vessels’.
Doppler phantom
T/F? Doppler phantoms can assess pulsed and continuous wave Doppler, but not color and power mode.
FALSE, all Doppler modalities
This kind of phantom evaluates slice thickness and elevational resolution.
slice thickness phantom
This kind of phantom contains a diffuse scattering plane that is at an angle to the incident sound beam.
slice thickness phantom
T/F? Soft tissue phantom can be used to measure slice thickness.
FALSE, only slice thickness phantoms
This refers to the ability of a system to display low-level echoes.
sensitivity
Two forms of sensitivity are…
normal and maximum.
At this sensitivity setting, all the pins, solid masses, and cystic structures in the test phantom are accurately displayed.
normal
All subsequent QA and performance measurements are made at __ sensitivity.
normal
T/F? Normal sensitivity setting should not vary from one test to the next.
true
At this sensitivity setting, the output power and amplification of the system are at maximum practical levels.
maximum
At which sensitivity level is the depth of the display measured?
maximum
This is the region close to the transducer where images are inaccurate.
the dead zone
The dead zone results from the time it takes the system to…
switch from transmit to receive mode.
__ frequency transducers have a thinner dead zone than __ frequency transducers.
Higher, lower
This can be positioned between the transducer and the patient to allow accurate imaging of superficial structures.
acoustic standoff or gel pad
This is the ability of the system to place reflections in proper position while imaging from different orientations.
registration accuracy
This describes the system’s accuracy in placing reflectors at correct depths located parallel to the sound beam.
range accuracy or vertical depth calibration
An increasingly deeper dead zone may indicate a…
cracked crystal, detached backing material, or a longer pulse duration.
Errors in range accuracy may be caused by…
system malfunction or the phantom sound speed not being 1540 m/s.
This is the system’s ability to place echoes in their correct position when the reflectors are perpendicular to the sound beam
horizontal calibration
Digital calipers should be checked in __ directions.
both vertical and horizontal
The accuracy of reflector depth positioning in A-, M-, B-mode and 2-D imaging is called…
depth calibration.
Axial resolution tests use pins that are __ to the sound beam.
parallel
Lateral resolution tests use pins that are __ to the sound beam.
perpendicular
This kind of phantom is used to evaluate the dimension, texture, and fill-in of cysts.
tissue equivalent
