Introduction to Basic Ultrasound Principles

A comprehensive set of flashcards covering fundamental concepts in ultrasound principles, acoustics, and imaging techniques.

What is the primary goal of a sonographer when using ultrasound?

To produce high-quality images that are free of artifacts.

What is the branch of physics that deals with sound and sound waves?

Acoustics.

What defines ultrasound?

Sound frequencies that are greater than 20 kHz.

What is the typical frequency range for medical diagnostic ultrasound?

1 to 20 MHz.

What device converts electrical energy into mechanical energy in ultrasound?

The ultrasound transducer.

What causes sound waves to travel through a medium?

The mechanical energy produced by alternating compression and rarefaction.

What is the average propagation velocity of sound in soft tissue?

1540 m/sec.

How does the speed of sound differ among air, liquids, and solids?

Sound travels slowest in gases, intermediate in liquids, and fastest in solids.

What is the unit used to measure the intensity of an ultrasound wave?

Decibel (dB).

What is power in the context of ultrasound?

The rate at which energy is transmitted.

How is intensity defined in ultrasound?

Power per unit area.

What effect does frequency have on wavelength?

Higher frequency results in shorter wavelength.

What is acoustic impedance?

A measure of a material's resistance to the propagation of sound.

What type of reflection occurs at large, smooth interfaces?

Specular reflection.

What is the result of refraction in ultrasound?

A change in the direction of sound when encountering different tissue speeds.

What is absorption in the context of ultrasound?

The loss of sound energy secondary to its conversion to thermal energy.

What phenomenon explains how ultrasound is generated?

The piezoelectric effect.

What does 'axial resolution' refer to in ultrasound imaging?

The ability to resolve objects at different depths along the direction of the sound pulse.

What affects lateral resolution in ultrasound?

The ability to resolve objects located side by side at the same depth, which can be varied by adjusting the focal zone.

What is attenuation in ultrasound?

The reduction of intensity and amplitude of sound waves as they travel through a medium.

What does a higher frequency probe provide in ultrasound imaging?

Better axial resolution but lesser penetration depth.

How does temperature affect the speed of sound in tissue?

Increased temperature generally leads to increased speed of sound.

What are the key units of measurement commonly used in ultrasound?

Decibels (dB), Hertz (Hz), watts (W), and meters (m).

What happens to ultrasound waves in air-filled structures?

They are impeded in transmission.

What characteristic of piezoelectric crystals is crucial for their function?

Their ability to convert between electrical and mechanical energy.

What type of ultrasound images are produced by higher amplitude echoes?

Brighter pixels in B-mode images.

What does the term 'wavelength' refer to in ultrasound?

The distance between successive peaks of a wave, inversely proportional to frequency.

Why does a gallstone produce a shadow on an ultrasound image?

Due to significant acoustic impedance difference and resultant attenuation.

What is meant by 'slice thickness' in ultrasound?

The thickness of the imaging slice, crucial for azimuthal resolution.

What outcomes result from scattering in ultrasound?

Redirection of sound in multiple directions, producing weaker signals.

What is the relationship between density and acoustic impedance?

Acoustic impedance increases with higher density or propagation speed.

What determines whether sound waves are reflected, transmitted, or absorbed?

The acoustic impedance differences at tissue interfaces.