Quiz yourself by thinking what should be in
each of the black spaces below before clicking
on it to display the answer.
Help!
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show | ACOUSTIC BOUNDARIES
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weakening of the sound as it propagates through a medium | show 🗑
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show | ATTENUATION
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unit of attenuation | show 🗑
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Factors affecting attenuation | show 🗑
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show | Attenuation, echoes
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______ frequencies are more attenuated than _____ frequencies. | show 🗑
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show | LOWER, HIGHER
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Where the molecules of the tissue are densely packed, attenuation will be much g____ than in l____ densely packed tissue | show 🗑
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show | INCREASES
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show | ATTENUATION COEFFICIENT
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show | dB/cm
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If the attenuation coefficient increases, attenuation _____. | show 🗑
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show | 0.5 dB)cm.
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show | SOFT TISSUE
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show | ABSORPTION
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The rate of absorption is directly ________ to the frequency. Higher frequency results in increased ultrasound absorption. | show 🗑
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two large structures of significantly different acoustic impedance form an interface, the interface becomes a reflector and some of the wave energy is reflected back to the transducer | show 🗑
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show | INCIDENT ENERGY AND ECHO
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the sound that hits an acoustic interface | show 🗑
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reflected beam | show 🗑
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show | ACOUSTIC IMPEDANCE MISMATCH
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The "values of Z for the soft tissues" are quite similar to one another. We conclude that reflections at boundaries between soft tissue will give rise generally s__ e__. | show 🗑
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The "Z value for bone" is several times higher than the soft tissue average.We conclude that reflection from gas/soft tissue interface gives rise to a l___e___. | show 🗑
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show | VERY LARGE ECHOES
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ANOTHER FACTOR THAT AFFECTS THE STRENGTH OF THE REFLECTION IS THE SIZE OF THE REFLECTOR. Reflectors can either be ___ or ____. | show 🗑
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show | SPECULAR REFLECTOR
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- reflecting interface is irregular in shape and its dimensions are smaller than the diameter of the ultrasound beam. - Incident beam is reflected in many different directions. | show 🗑
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show | NORMAL INCIDENCE
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Denotes a direction of travel of the incident ultrasound that is not perpendicular to the boundary between two media | show 🗑
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- when an ultrasound waves strikes a boundary or interface between 2 small structures and the wave is scattered in different directions - responsible for providing the internal texture of organs in the image | show 🗑
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when the scatter in equal in all direction | show 🗑
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- change in direction of a sound beam as it enters the medium. - Transmission with a bend | show 🗑
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show | SNELL'S LAW
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show | OBLIQUE INCIDENCE AND DIFF. PROPAGRATION SPEED ON EITHER SIDE OF THE BOUNDARY
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As a beam of ultrasound travels through it will diverge. This divergence will result in the same power spread over larger area. The intensity of the beam will therefore be reduced | show 🗑
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show | TRANSDUCER
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show | PHYSICAL HOUSING
, ELECTRODES, PIEZOELECTRIC ELEMENTS
BACKING MATERIAL
, IMPENANCE MATCHING LAYER
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show | PHYSICAL HOUSING
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- "Grounded electrode - " Protects patients from electric shock. | show 🗑
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- "Live Electrode - " Abuts against a thick backing block. | show 🗑
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- " transducer element" - most important component - Approx. 6-19 mm in diameter and 0.2-2 mm in thickness - Crystalline materials - dipolar molecules | show 🗑
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naturally occurring material with piezoelectric properties | show 🗑
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show | LEAD ZIRCONATE TITANATE(PZT)
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show | To press and ember
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- Was described 1880 by Pierre and Jacques Curies - some materials produced a voltage when deformed by an applied pressure. | show 🗑
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Eliminate the vibrations from the "back" face and to control the length of vibrations from the face of the crystals. | show 🗑
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show | MATCHING LAYER
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Area through which the sound energy emitted from the transducer travels | show 🗑
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2 regions of Ultrasound beam | show 🗑
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show | NEAR FIELD(FRESNEL ZONE)
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show | FAR FIELD(FRAUNHOFER ZONE)
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show | FOCUS OR FOCAL POINT
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energy from the transducer that radiates at various amgles from the transducer face | show 🗑
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arrangement of crystals within the transducer | show 🗑
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types of electronic array transducer | show 🗑
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show | FOOTPRINT
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width of the image that is seen on the screen | show 🗑
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show | LINEAR ARRAY
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show | LINEAR ARRAY
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- similar to the linear areay but the transducer face is formed curve(convex) - "sector arrays" | show 🗑
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show | CURVILINEAR ARRAY TRANSDUCERS
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show 🗑
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transducer designed to enter the body via the vagina, rectum, esophagus or blood vessel(catheter-mounted type) | show 🗑
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1. ultrasound transducers should not be sterilized | show 🗑
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show | CURIE POINT
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Created by:
kkei