The routine, periodic evaluation of an ultrasound system to guarantee optimal image quality

Must be performed periodically and routinely

• Assessment of system components
• Repairs
• Preventative maintenance
• Record keeping

• Guarantee proper operation of the system
• Detect gradual changes
• Minimize downtime
• Reduce the number of non-diagnostic exams
• Reduce the number of repeat scans

• Tissue equivalent phantom
• Doppler phantom
• Beam profile/slice thickness phantom

• Test under known, defined conditions
• Use constant instrument settings
• Use a phantom with measurable characteristics
• Image in an identical environment

Used to evaluate characteristics, such as gray scale (echogenicity) and tissue texture, and multi-focus and adjustable-focus phased array transducers

Similar to soft tissue in their:

~Speed of sound

~Attenuation

~Scattering characteristics

~Echogenicity

Device used to evaluate Doppler systems

Include a circulation pump that propels fluid through vessels embedded in a tissue equivalent phantom

Assess the characteristics of all Doppler modalities, including pulsed, continuous wave, color, and power mode

• Vibrating string
• Moving belt
• Flow phantom (choice option)

Contains a diffuse scattering plane that is at an angle to the incident sound beam

Measures the beam geometry perpendicular to the imaging plane

Determines elevational resolution

Degrades an image when thicker than either the beam width (lateral resolution) or pulse length (axial resolution)

~Diminish spatial resolution and ability to visualize small, low contrast reflectors

~Cystic structures may appear filled in

• Sensitivity
• Dead one
• Registration accuracy
• Focal zone
• Axial resolution
• Lateral resolution
• Compensation operation/uniformity
• Mock cysts and solid masses
• Display, hardcopy output, and gray scale dynamic range

The ability of a system to display low-level echoes

Normal and Maximum

Settings at which all the pins, solid masses, and cystic structures in the test phantom area accurately displayed

Output power, TGC, and amplification are adjusted to establish this

Output power and amplification of the system are set to their highest practical levels

A tissue-equivalent phantom is imaged and the depth of tissue-like texture on the display is measured

Maximum visualization depth is used to assess sensitivity

The region close to the transducer where images are inaccurate

Extends from the transducer to the shallowest depth from which meaningful reflections appear; the shallowest depth at which uniform tissue texture appears

Results from transducer ringing and the time it takes the system to switch from the transmit to the receive mode

Reduced with higher frequency transducers

Increasingly deeper depth may indicate cracked crystal, detached backing material, or longer pulse duration

The ability of the system to place reflections in proper positions while imaging from different orientations

• Range accuracy
• Horizontal calibration
• Distance measurement accuracy

Describes the system's accuracy in placing reflectors at correct depths located parallel to the sound beam

Errors may be caused by system malfunction or the phantom's speed of sound is different than 1,540 m/s

Components of the ultrasound system used to measure distances

Digital calipers checked in both vertical and horizontal directions

The depth at which the intensity is the highest and the beam is narrowest

Best lateral resolution

Systems with dynamic receive focusing should produce narrow reflections over a wide range of depths

The smallest distance at which two ins positioned parallel to the sound beam are displayed as two distinct echoes

Evaluated by scanning sets of successively closer spaced pins within the phantom

The minimum distance at which two side-by-side pins are displayed as two distinct images

Measure the width of reflections n the display that are created by point targets in the phantom; approximates the beam diameter at that depth

With traditional transducers, beam diameter varies with depth and is narrowest at the focus

The system's ability to display similar reflectors in the phantom with echoes of equal brightness

With proper TGC, identical reflectors should have the same appearance on the monitor, regardless of depth

Tissue equivalent phantom used to evaluate dimension, texture, and filling of fluid-filled objects

Should accurately display hollow structures as hyperechoic