Ch. 1 Foundations of Sonography Flashcards
Change in the direction of propagation of a sound wave transmitted across an interface where the speed of sound varies
Refraction
Angle at which a sound beam strikes the interface between two types of tissue
Angle of incidence
Power per unit area
Intensity
Special material in the transducer that has the ability to convert electric impulses into sound waves
Crystal
Propagation of energy that moves back and forth or vibrates at a steady rate
Wave
Any device that converts energy from one form to another
Transducer
Number of cycles per second that a periodic event or function undergoes
Frequency
Measure of material’s resistance to the propagation of sound; expressed as the product of acoustic velocity of the medium and density of the medium
Acoustic Impedance
Generation of electric signals as the result of an incident sound beam on a material that has piezoelectric properties
Piezoelectric Effect
Region over which the effective width of the sound beam is within some measure of its width at the focal distance
Focal Zone
Reduction in amplitude and intensity of a sound wave as it propagates through a medium
Attenuation
Passive force in opposition to another, active force; occurs when tissue exerts pressure against the flow
Resistance
Surface forming the boundry between media having different properties
Interface
Region of increased particle density
Compression
Distance over which a wave repeats itself during one period of oscillation
Wavelength
Refers to the minimum distance between two structures positioned along the axis of the beam where both structures can be visualized as separate objects
Axial Resolution
Rate of energy flow over the entire beam of sound
Power
Unit used to quantitatively express the ratio of two amplitudes or intensities
Decible (db)
1,000,000 Hz
Megahertz (MHz)
Ability of the transducer to distinguish between two structures adjacent to one another
Resolution