Ultrasound Physics

What defines frequency in diagnostic ultrasound?

Frequency is the number of cycles of an acoustic variable that occur in one second.

What is the frequency range of diagnostic ultrasound?

The frequency range of diagnostic ultrasound is 2 - 13 MHz.

What is the formula for frequency (f)?

Frequency (f) = Number of cycles / Time (in seconds).

How is the period defined in ultrasound?

Period is the time required to complete a single cycle.

What is the unit of measurement for wavelength?

Wavelength is measured in meters (m) or millimeters (mm).

What is the relationship between frequency and wavelength?

Wavelength has an inverse relationship with frequency; higher frequency results in shorter wavelength.

What does amplitude represent in terms of an acoustic variable?

Amplitude is the difference between the average value and the maximum value of an acoustic variable.

How is power defined in the context of sound?

Power is the rate at which energy is transferred in an area.

What does intensity measure in a sound beam?

Intensity measures the concentration of energy in a sound beam that passes through a unit area.

What is the definition of pulsed ultrasound?

Pulsed ultrasound is a collection of pulses that are sent to the body, separated by gaps of no ultrasound.

Define Pulse Repetition Frequency (PRF).

PRF is the number of pulses occurring in one second, expressed in kilohertz (kHz).

What is the formula for calculating Pulse Repetition Period (PRP)?

PRP (ms) = 1 / PRF (kHz).

What determines the duty factor (DF) in pulsed ultrasound?

DF is determined by the fraction of time that pulsed ultrasound is on.

What is attenuation in ultrasound?

Attenuation is the decrease in intensity, power, and amplitude of a sound wave as it travels.

What is the Attenuation Coefficient?

The Attenuation Coefficient (Ac) is the amount of attenuation that occurs for each cm the sound wave travels, measured in dB/cm.

Define impedance in the context of ultrasound.

Impedance is a measure of how much of an incident sound wave is reflected back or transmitted into another medium.

What is the intensity reflection coefficient (IRC)?

IRC is the percentage of the ultrasound pulse that is reflected back when the sound beam passes from one medium to another.

What are harmonics in ultrasound?

Harmonics are frequencies that are multiples of the transmitted sound frequency, improving image quality.

Define normal incidence in ultrasound.

Normal incidence occurs when the incident sound wave is perpendicular to the boundary, usually resulting in reflection and transmission.

What is Snell's Law in relation to refraction?

Snell's Law describes the relationship between the angles of incidence and transmission, and the propagation speeds in different media.

How is the range equation defined?

The range equation calculates the time taken for a pulse to travel to a reflector and back to the transducer.

What does a higher frequency imply for attenuation?

A higher frequency increases attenuation as sound travels through tissues.

How is bandwidth defined in ultrasound?

Bandwidth is the range of frequencies contained in a pulse, with shorter pulses having a broader bandwidth.

What is the significance of a low Q factor?

A low Q factor indicates substantial damping, shorter pulses, and a broad bandwidth, which leads to better image quality.