Term
| Portions of an image that are brighter than surrounding tissues, or tissues that appear brighter than normal. |
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Definition
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Term
| Portions of an image that are not as bright as surround tissues, or tissues that appear less bright than normal. |
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Definition
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Term
| Without echoes; echo-free |
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Definition
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Term
| Describes structures with equal echo brightness. |
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Definition
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Term
| A portion of tissue or a structure that has similar echo characteristics throughout. |
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Definition
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Term
| Displaying a variety of different echo characteristic within the tissue. |
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Definition
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Term
| What are Ultrasound artifacts? |
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Definition
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Term
What are some errors imaging? |
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Definition
- Not real
- Missing reflectors
- Improper brightness
- Improper shape
- Improper size
- Improper position
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Term
| What are causes of artifact? |
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Definition
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Term
| What are the 6 assumptions of imaging systems? |
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Definition
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Sound travels in a straight line.
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Sound travels directly to a reflector and back.
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Sound travels in soft tissue at exactly 1540 m/s.
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Reflections arise only from structures positioned in the beam’s main axis,
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The imaging plane is very thin.
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The strength of a reflection is related to the characteristics of the tissue creating the reflection
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Term
| Multiple, equally spaced echoes caused by the bouncing of the sound wave between two strong reflectors positioned parallel to the ultrasound beam. Violation of assumption 2. |
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Definition
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Term
| Solid hyperechoic line directed downward. AKA ring down artifact. Violation of assumption 2. |
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Definition
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Term
| Hypoechoic or anechoic region extending downward from a highly attenuating structure. Violation of assumption 6. |
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Definition
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Term
| Hypoechoic region extending down from the edge of a curved reflector. Caused by a decrease in intensity. Violation of assumption 6. |
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Definition
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Term
| Hyperechoic region beneath tissues with abnormally low attenuation. Violation of assumption 6. |
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Definition
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Term
| Side-to-side region of an image appears brighter than tissues at other depths. AKA focal banding. (Appears as if a TGC is set improperly). Violation of assumption 6. |
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Definition
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Term
| Created when sound reflects off a strong reflector and is redirected toward a second structure. The artifact is located deeper than the real structure. The mirror is always located along a straight line between the transducer and the artifact. Violation of assumption 1 and 2. |
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Definition
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Term
| Mirror image artifact that appears on a spectral Doppler display. |
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Definition
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Term
| Created when a sound wave propagates through a medium at a speed other than that of soft tissue (1540 m/s). Speed errors appear as a step-off, as if structures are “split” or “cut.” AKA range error artifact. Violation of assumption 3. |
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Definition
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Term
| Appears when sound energy is transmitted in a direction other than along the beam’s main axis. The artifact and the true reflector are located side by side at the same depth. Lobe artifact degrades lateral resolution. Violation of assumption 2. |
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Definition
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Term
| Created when a sound pulse changes direction during transmission. When a sound wave strikes a boundary obliquely and the media on either side of the boundary have different propagation speeds. Refraction artifact degrades lateral resolution. A copy is side-by-side, or the same depth as the true reflector. Violation of assumption 1. |
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Definition
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Term
| The beam flares out like a bell of a trumpet; therefore, reflections from structures above or below the assumed imaging plane may appear in the image. AKA section thickness artifact or partial volume artifact. The true reflector lies either above or below the assumed imaging plane but is displayed within the image. Violation of assumption 5. |
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Definition
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Term
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Definition
| Lateral resolution artifact |
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Term
| Created when a long pulse strikes two closely spaced structures, where on is in front of the other. The structures are parallel to the beam’s main axis. Only one reflection will appear on the image if the structures are closer together than one-half the spatial pulse length. |
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Definition
| Axial resolution artifact |
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Term
| Created when sound pulses glance off a second structure on the way to or from the primary reflector. As a result, the transmit path length differs from the return path length. Violation of assumption 2. |
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Definition
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Term
| When a sound beam strikes a curved or oblique reflector, some of the reflected sound may be directed away from the transducer. The amplitude of the reflection received by the transducer may be less than expected. |
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Definition
| Curved and oblique reflectors |
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Term
| Related to overall detail in an image. It is determined by multiple factors, including line density (closely packed sound pulses), axial resolution, and lateral resolution. With high line density, the image exhibits great detail, and the spatial resolution is exceptional. With a low line density (wider gaps between the sound pulses) the image exhibits less detail, and the spatial resolution is poor. |
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Definition
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Term
| Occurs when a reflecting structure is located deeper than the imaging depth of the image. This reflector is placed at the shallow location on the image. Range ambiguity artifact is eliminated by increasing the PRP. Longer PRP means deeper imaging and decreased PRF. |
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Definition
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Term
Appears as small amplitude echoes and results from many sources, including electrical interference, signal processing, and spurious reflections. Noise is more likely to affect low-level hypoechoic regions rather than bright echogenic areas. |
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Definition
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Term
| Noise resulting from the constructive and destructive interference of small sound wavelets. |
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Definition
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Term
| Another form of noise, is the presence of false echo signals arising from locations outside the main sound beam. Side lobes, grating lobes, and section thickness artifact are sources of clutter. |
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Definition
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Term
| Reduces an image’s noise content. The goal of harmonic imaging is to selectively distinguish meaningful reflections from noise, thereby increasing the signal-to-noise ratio. |
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Definition
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Term
| Four requirements for a QA program are: |
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Definition
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Assessment of system components
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Reparirs
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Preventive maintenance
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Record keeping
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Term
| The five goals of a QA program are: |
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Definition
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Term
| What are the methods used for QA? |
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Definition
Test under known, defined conditions
Constant instrument settings
Use phantom with measurable characteristics
Image in identical environment |
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Term
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Have ultrasonic features similar to soft tissue, such as, speed of sound, attenuation, scattering characteristic, and echogenicity.
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Gray scale is evaluated with this phantom since it contains small scatterers that act like soft tissue. Structures that mimic hollow cysts and solid masses are also embedded in the phantom.
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Definition
| Tissue equivalent phantom |
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Term
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Flow phantoms are the devices of choice for evaluating Doppler systems. Modern Doppler phantoms include a circulation pump which propels fluid through vessels embedded in a tissue equivalent phantom. Other Doppler phantoms contain vibrating strings or moving belts.
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Doppler phantoms assess the characteristics of all Doppler modalities, including pulsed, continuous wave, color, and power mode.
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Definition
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Term
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Focal Zone
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Longitudinal resolution
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Lateral resolution
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Horizontal registration
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Vertical registration
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Definition
| Beam profile/slice thickness phantom |
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Term
| What is minimum sensitivity? |
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Definition
| With the TGC set flat, increasing the gain from its minimum value to the pint when an echo is displayed on the CRT determines the minimum sensitivity. |
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Term
| What is normal sensitivity? |
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Definition
| The gain setting where all of the pins in the AIUM test object are displayed on the CRT. Normal sensitivity is found at a higher gain than the minimum sensitivity. All other performance measurements are made at this setting. |
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Term
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Definition
| When adjustments make changes in display or echo brightness from scarcely visible to fully saturated, sensitivity is being assessed. |
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Term
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Definition
| It is the distance close to the transducer that cannot produce an accurate image on the display. |
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Term
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Definition
| The machine's ability to display echoes in the proper depth. |
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Term
| What is registration accuracy? |
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Definition
| The machine's ability to place echoes in proper positions while imaging from different orientations. |
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Term
| What is horizontal calibration? |
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Definition
| The machine's ability to position echoes in their correct position along a distance perpendicular to the US beam. |
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Term
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Definition
| The depth at which the intensity is the highest and the beam is the narrowest. |
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Term
| What is longitudinal resolution? |
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Definition
| The smallest distance at which two pins are displayed as two separate echoes, front to back or parallel to the sound beam. |
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Term
| What is lateral resolution? |
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Definition
| The minimum distance that two rods are displayed as two separate images can be determined. Perpendicular to the sound beam. |
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Term
| What is the Gold Standard? |
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Definition
| A "perfect" technique, for example MRI or angiography, that we deem 100% accurate to which our ultrasound results are compared. |
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