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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| "tissue interface" - position within the tissue where the values of acoustic impedance change | show 🗑
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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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| show | DECIBEL
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| Factors affecting attenuation | show 🗑
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| ______will not only occur in the beam of sound produced by the transducer as it produces propagates through tissue, but also in returning ______ as the travel back to the transducer. | show 🗑
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| show | HIGHER, LOWER
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| ____ frequency penetrates deeper than _____ frequency because they are attenuated to a "lesser" degree | show 🗑
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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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| show | INCREASE
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| show | 0.5 dB)cm.
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| term used to describe the average tissue that makes up the soft tissues of the human body (e.g., liver, kidney, spleen). | show 🗑
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| Process by which energy in the ultrasound beam is transferred to the propagating medium, where it is transformed into a different form of energy, mostly heat. The medium is said to absorb energy from the beam | show 🗑
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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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| show | REFLECTION
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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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| show | SPECULAR OR DIFFUSE
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| - boundary is smooth and larger than the beam. - Angle of incidence = angle of reflection | show 🗑
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| show | DIFFUSE REFLECTOR
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| describe when the beam is perpendicular to the interface | show 🗑
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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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| show | SCATTERING
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| show | RAYLEIGH SCATTERING
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| show | REFRACTION
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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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| show | INSIDE ELECTRODE
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| show | PIEZOELECTRIC ELEMENT
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| show | QUARTZ
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| - Commonly used materials - man made ceramic - more efficient, better sensitivity and can be easily shaped | show 🗑
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| Greek term "piezo" means___ and Elektron ____ | show 🗑
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| show | PIEZOELECTRICITY
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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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| - Sandwiched between the piezoelectric crystal and the patient. - Has acoustic impedance value halfway between that of the crystal and soft tissue. | show 🗑
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| show | ULTRASOUND BEAM
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| show | NEAR FIELD AND FAR FIELD/FRESNEL ZONE OR FRAUNHOFER ZONE
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| show | NEAR FIELD(FRESNEL ZONE)
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| Region "farthest" from the transducer and characterized by the divergence of the beam with great variation in intensity. | show 🗑
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| show | FOCUS OR FOCAL POINT
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| show | SIDE LOBES
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| show | ARRAY
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| types of electronic array transducer | show 🗑
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| show | FOOTPRINT
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| show | FIELD OF VIEW
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| show | LINEAR ARRAY
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| - image superficial structures and vessels - operate at frequencies above 4MHz - used for vascular, small parts | show 🗑
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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 | PHASED ARRAY
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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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| temperature at which polarization in a crystal is lost | show 🗑
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Created by:
kkei