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55 Cards in this Set
- Front
- Back
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What is quality assurance |
Routine, periodic evaluation of an ultrasound system to guarantee optimal image quality |
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Quality assurance evaluations must be performed |
Periodically and routinely The sonographer is responsible for implementing quality assurance |
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Four requirements for a quality assurance program |
Assessment of system components Repairs Preventative maintenance Record keeping |
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Several devices enable the sonographer to perform quality |
Test under known, define conditions Use constant instrument settings Use a phantom with measurable characteristics Image in an identical environment |
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Five goals of a quality assurance program |
Guarantee proper operation of the system Detect gradual changes Minimize downtime Reduce the number of non-diagnostic exams Reduce the number of repeat scans |
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Several devices enabler snugger for to perform quality assurance |
Tissue equivalent phantom Doppler phantom Beam profile/slice thickness phantom |
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An objective statement |
Unbiased Not affected by an individual‘s previous experience, preference, or taste Information is factual |
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Hey subjective statement |
Influence by an individuals experience or believes Colored by a person‘s perspective or view of reality Cannot be verified Information is affected by opinion believe or Sumption |
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Quality assurance programs should be based on |
Objective standards |
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Tissue equivalent phantoms have ultrasonic fig featuresSimilar to |
Soft tissue They are used to evaluate characteristics such as grayscale and tissue texture, multi focus and adjustable focus phased array transducer’s |
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Tessio equivalent phantoms are similar to soft tissue in the following ways |
Speed of sound Attenuation Scattering characteristics Echogenicity |
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Slice thickness phantom contains |
A diffuse scattering plane that is at an angle to the incident sound Beam Mimics soft tissue |
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Thicker slices diminish When the sound beam is overly thick |
Spatial resolution (image detail) and reduce the ability to visualize small, low contrast reflectors Cystic structures may appear filled in |
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Where is grayscale evaluated |
In tissue equivalent phantom because it contains small scatters that act like soft tissue |
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Nylon strings may be in bedded in the phantom to produce |
Reflections at strategic locations |
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Flow phantoms are the devices of choice for |
Evaluating Doppler systems |
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Modern Doppler phantoms include |
Hey circulation pump which propels fluid through vessels embedded in a tissue equivalent phantom |
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Other doppler phantoms contain |
Vibrating strings or moving belts |
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Doppler phantoms include |
Vibrating string Moving belt Flow phantom |
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Doppler phantoms assist the characteristics of all Doppler modalities including |
Pulsed, continuous wave,color, and power mode |
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Slice thickness determines |
Elevational resolution |
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Slice thickness is most likely to degrade |
Image quality because the imaging plane is thicker than either the beam with or the pulse length Beam with determines lateral resolution Pulsed length determines axial resolution |
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Sensitivity refers to |
The ability of a system to display low-level echoes |
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Two forms of sensitivity or |
Normal Maximum |
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Normal sensitivity settings are those at which |
All the pans, solid masses, and cystic structures in the test phantom are accurately displayed Output power, TGC, and amplification are adjusted to establish normal sensitivity |
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Normal sensitivity settings should not very |
From one routine evaluation to the next |
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Maximum sensitivity is evaluated with |
Output power and amplification of the system set to the maximum practical levels With the settings eight tissue equivalent phantom is image, and the depth of tissue like texture on the display is measured |
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Maximum visualization depthIs used to assess |
Sensitivity, and should not differ from one routine evaluation to the next |
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Sensitivity is also assessed win |
Hey sonographer adjusts system controls to change echo brightness from barely visible to full brightness |
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Dead zone is a region close to |
The transducer where images are in accurate It extends from the transducer to the shallowest Deb from which meaningful reflections appear |
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The accuracy of reflector depth positioning in a mode, M mode, B-mode, and 2D imaging is called |
Depth calibration |
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Horizontal calibration is the systems ability to |
Lace air goes in the correct position when the reflectors are perpendicular to the sun beam |
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Digital calipers should be checked in both |
Vertical and horizontal directions |
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Focus is the depth at which |
Intensity is the highest in the beam is the narrowest Focal zone surrounds the focus |
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What resolution is excellent in the focal zone because the beam is an arrow |
Lateral resolution |
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Systems with dynamic receive focusing should produce |
Narrow reflections over a wide range of dips |
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Axial resolution is the |
Smallest distance at which two Pins position parallel to the sound beam are displayed as two distinct echoes |
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Axial resolution is evaluated by scanning |
Set of successively closer space pins within the Phantom |
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Lateral resolution is the |
Minimum distance at which to side by side pins are displayed at two distinct images |
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Another method to evaluate letter resolution is to |
Measure the width of reflections on the display that are created bypoint Targets in the phantom |
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Information within the dead zone is |
Unreliable and may not be used in diagnostics sitting |
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With traditional transducers beam diameter varies with |
Depth and is narrowest at the focus |
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Uniformity describes the systems ability to |
Display similar reflectors in the phantom with echoes of equal brightness |
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With proper TGC identical reflectors should have |
The same appearance on the monitor, regardless of their depth |
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Tissue equivalent phantom is used to evaluate |
Die mention, texture, and fill in of cysts This system should accurately display hollow structures as anechoic and solid structures as hyperechoic |
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Adjusting the systems output power and amplification should produce |
Changes in the grayscale display |
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It is important to compare the relationship between the image on the system screen with the output of all other display devices such as |
Remote viewing stations |
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Dead zone results from |
Transducer ringing in the time it takes a system to switch from the transmit to the receive mode |
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The dead zone is assessed with the |
The shallowest series of pins in a test object |
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With tissue equivalent phantom, the dead zone is the shallowest depth at |
Which uniform tissue texture appears Higher frequency transducers have thinner dead zone then lower frequency |
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On acoustic standoff, or gel pad, position between the transducer and the patient allows |
Accurate imaging of important superficial structures A 50 cc bag of IV fluid may also be used |
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An increasingly deeperDead zone may indicate |
A cracked Crystal, detached backing material, or longer pulse duration |
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Registration accuracy is the ability of the system to |
Play’s reflections in proper positions well imaging from different orientations |
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Range accuracy, or Describes |
Vertical Deb calibration This systems accuracy and placing reflectors are correct depths located parallel to the sounds Beam |
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If differences appear between the ultrasound scan and the actual pin locations in the test object, the error may be caused by |
System malfunction The speed of sound in the phantom is different than 1540 m/s |
