Attenuation
These three processes contribute to the attenuation of a sound wave as it travels through a medium.
What are absorption, reflection, and scattering?
In ultrasound, this term refers to the way a sound wave strikes a boundary.
What is incidence?
At a boundary between two media, all of a sound wave’s energy must be accounted for. The sum of the percentages reflected and transmitted illustrates this principle.
What is conservation of energy?
This phenomenon occurs at the border between two media only if the wave strikes at an angle other than 90°, causing the wave to bend as it crosses the boundary.
What is refraction?
This term describes a structure that does not produce echoes and appears completely black on ultrasound.
What is anechoic?
This occurs when part of a sound wave strikes a boundary and bounces back toward the transducer instead of continuing forward.
What is reflection?
Terms like perpendicular, orthogonal, right angle, or 90° are used to describe this type of incidence when a sound wave strikes a boundary.
What is normal incidence?
This represents the percentage of the sound beam that passes forward when it strikes a boundary between two media.
What is the intensity transmission coefficient (ITC)?
This law governs the bending of a sound wave as it crosses a boundary between two media, also known as refraction.
What is Snell’s Law?
This term describes a structure that produces more echoes than surrounding tissue, appearing brighter on the image.
What is hyperechoic?
This type of reflection occurs when sound strikes an irregular or rough boundary, causing the wave to scatter in many directions rather than returning in just one.
What is diffuse reflection?
This is the term for the intensity of the sound beam before it strikes a boundary.
What is incident intensity?
This coefficient, represents the fraction or percentage of a sound wave’s intensity that is reflected when it strikes a boundary between two media.
What is the intensity reflection coefficient (IRC)?
This is the thickness of tissue required to reduce the sound beam’s intensity to one-half its original value.
What is half-value layer thickness?
This term describes a structure that produces fewer echoes than surrounding tissue, appearing darker on the image.
What is hypoechoic?
This occurs when ultrasound waves strike a boundary with irregular surfaces or small structures, causing the sound to radiate in many directions.
What is scattering?
This is the intensity of the sound beam that returns toward the transducer after striking a boundary.
What is reflected intensity?
A 75 W/cm² sound wave strikes a boundary and is totally reflected. This is the intensity reflection coefficient.
What is 100%?
A sound wave strikes a boundary at normal incidence, and 73% of its intensity is reflected. This percentage of the wave’s intensity is transmitted into the second medium.
What is 27%?
This term refers to a structure that produces echoes similar to surrounding tissue, making it appear about the same brightness.
What is isoechoic?
This special type of scattering occurs when a structure’s dimensions are much smaller than the ultrasound wavelength, causing the sound wave to be redirected equally in all directions.
What is Rayleigh scattering?
This is the intensity of the sound beam that continues forward into the second medium after striking a boundary.
What is transmitted intensity?
When a 45 W/cm² sound wave meets a boundary and all the energy is reflected, this is the intensity of the reflected wave.
What is 45 W/cm²?
Refraction of a sound wave occurs at a boundary only when these two conditions are met.
What are:
The wave strikes at an angle other than 90° (oblique incidence)
The two media have different sound speeds
This general term describes a tissue or structure that produces any echoes visible on ultrasound.
What is echogenic?