Reflection and Refraction
The portion of a sound that is returned from the boundary of a medium. (echo) The angle of incidence influences the reflected and refracted waves.
Refraction- the change of sound direction on passing from one medium to another.
Acoustic Mismatch - the boundary between two different media where reflection and refraction occurs.
Attenuation - the decrease in amplitude and intensity as a sound wave travels through a medium.
Acoustic Mismatch - the boundary between two different media where reflection and refraction occurs.
Attenuation - the decrease in amplitude and intensity as a sound wave travels through a medium.
Specular - echoes originating from relatively large, regularly shaped objects with smooth surfaces. These echoes are relatively intense and angle dependent. (i.e. IVS, valves)
Scattered - echoes originating from relatively small, weakly reflective, irregularly shaped objects are less angle dependant and less intense. (ie. blood cells)
Scattered - echoes originating from relatively small, weakly reflective, irregularly shaped objects are less angle dependant and less intense. (ie. blood cells)
Scattering: Reflection and Refraction are affected by the material being imaged.
Frequencies:
Frequencies for adult imaging - 2.0mHz to 3.0mHz.
Frequencies for pediatric imaging - 5.0mHz to 7.5mHz to 12mHz.
Effect of higher frequencies on penetration - the higher the frequency the less penetration, the lower the frequency the greater the penetration.