Phantoms

focus

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

both vertical and horizontal

digital calipers should be checked in what directions

focus

focal zone is the area surrounding the what

imaging plane thicker than either beam width or pulse duration

how is slice thickness most likely to degrade image quality

reduced

how is the ability to visualize small, low contrast structures affected by thick slices

system malfunction differences in speed of sound

if differences appear between the ultrasound scan and the actual pin locations in the test object, the error may be cause by:

higher

is a thinner dead zone is created with a lower or higher frequency transducer

no

is information from the dead zone used in a diagnostic setting

thinner

is the ability to visualize small, low contrast structure done with thicker or thinner slices

tissue equivalent phantom

phantom composed of gelatin with microscopic graphite particles mixed uniformly throughout the tank, gives textured type appearance, has nylon pins, mock cysts and solid masses

AIUM 100mm Test Phantom

phantom composed of stainless steel rods filled with alcohol and water (will just look black with pins, only tests speed it travels, no mock cysts or structures)

no

should sensitivity settings vary from one routine evaluation to the next

pulsed continuous wave color power mode

the Doppler phantom assesses what characteristics of doppler modalities

shallowest

the dead zone is assessed with the ______ set of pins in a phantom

transmit to receive mode

the dead zone results from transducer ringing and the time it takes the system to switch from what to what

distance measurement accuracy

the periodic evaluation of the components of the US system used to measure distances is termed

spatial

thicker slices degrades what resolution

TGC

uniformity allows us to see if what system control is working properly

compensation operation

uniformity is AKA

tissue equivalent phantom bar test phantom SMPTE test pattern (society of motion picture and television engineers)

what are some test pattern to evaluate to make sure hard copy output and PACS images are matching the detail seen on the US systems monitor

none

what concentration of graphite particles are put together to create a cystic looking structure in a tissue equivalent phantom

high

what concentration of graphite particles are put together to create a very bright structure like a stone or hemangioma in a tissue-equivalent phantom

uniformity

what describes the systems ability to display similar reflectors in the phantom with echoes of equal brightness

horizontal calibration

what describes the systems ability to place echoes in their correct position when the reflectors are perpendicular to the sound beam

range accuracy (vertical depth calibration)

what describes the systems accuracy in placing reflectors at correct depths located parallel to the sound beam

pulse length

what determines axial resolution

beam width

what determines lateral resolution

size of structures distortion of grid patterns contrast correct number of shades of gray

what discrepancies should you look for when evaluating differences seen on US screen with hard copy output and PACS

Maximum sensitivity

what form of sensitivity is evaluated with the output power and amplification of the system set to the maximum practical levels

Normal sensitivity

what form of sensitivity settings are those at which all pins, solid masses, and cystic structures in the test phantom are accurately displayed

output power, TGC, amplification

what is adjusted to establish normal sensitivity

vertical depth calibration

what is range accuracy AKA

sensitivity

what is the ability a system to display low-level echoes

registration accuracy

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

lateral resolution

what is the minimum distance at which two side-by-side (perpendicular) pins are displayed as two distinct images

dead zone

what is the region close to the transducer where images are inaccurate - extends from the transducer to the shallowest depth from which meaningful reflections appear

axial resolution

what is the smallest distance at which two pins positioned parallel to the sound beam are displayed as two distinct echoes

measure distance b/w the targets side to side

what is the technique for horizontal calibration

measure distance b/w first and last target

what is the technique for range accuracy

slice thickness phantom

what phantom is used to asses the slice thickness and its effect upon image accuracy

tissue equivalent

what phantom is used to evaluate gray scale

Doppler phantom

what phantom uses a circulation pump to mimic a flowing vessel

cracked crystal detached backing material longer pulse duration

what possible problems could create discrepancies or increasingly deeper dead zone

speed of sound attenuation scattering characteristics echogenicity

what properties does the tissue equivalent phantom have that are similar to actual soft tissue

elevational

what resolution is determined by slice thickness

lateral

what resolution is excellent at the focal zone

call service engineer

what should you do if compensation operation is not working properly

output power, amplification

what system controls can you adjust to produce changes in gray scale display

scan vertical target group, measure distance to smallest/brightest target in group

what technique is used to asses single focal zone

filled in

when the beam is overly thick, how do cystic structures appear