Understanding Ultrasound Physics

Flashcards based on key concepts from lecture notes on ultrasound physics, focusing on instrumentation, receiver functions, and imaging principles.

What are some synonyms for pulser voltage in ultrasound systems?

Output gain, acoustic power, pulser power, energy output, transmitter output, power, or gain.

What is the purpose of the Thermal Index (TI) and Mechanical Index (MI) in ultrasound?

They are measurements that standardize transducer output while displaying on modern ultrasound systems.

How does modifying transducer output affect ultrasound imaging?

It changes the pulses transmitted to the body, affecting the reflections received and altering the brightness of the entire image.

What is noise in the context of ultrasound?

Noise is a random and persistent disturbance that obscures or reduces signal clarity in images.

What is the effect of Pulse Repetition Period (PRP) on imaging depth?

Short PRP results in superficial imaging, while long PRP allows for deeper imaging.

What is a beam former in ultrasound systems?

A device that functions with array transducers to optimize the transmitted ultrasound beam and establish time delays during reception.

What are the primary functions of an ultrasound receiver?

Amplification, Compensation, Compression, Demodulation, and Reject.

What does the ALARA principle stand for in ultrasound safety?

As Low As Reasonably Achievable; it guides minimizing patient exposure during imaging.

What is dynamic frequency tuning in ultrasound?

A feature that uses only high-frequency parts for superficial imaging and lower frequencies for deeper imaging to improve image quality.

How does output power affect the signal-to-noise ratio in ultrasound imaging?

Increasing output power improves the signal-to-noise ratio as it strengthens diagnostic echoes while keeping noise levels constant.

What is the difference between output power and receiver gain?

Output power affects image brightness and patient exposure, whereas receiver gain only adjusts the brightness of the image without affecting exposure.

What is the role of rejection in the ultrasound receiver?

Reject allows control over whether low-level gray scale information appears on the displayed image to filter out noise.

What is preamplification, and where does it occur?

Preamplification is the process of improving signal quality close to the transducer's active elements before the signal is amplified.

What does the compensation function do in an ultrasound receiver?

Compensation corrects for attenuation so that images remain uniformly bright regardless of depth.

What is a channel in ultrasound systems?

A channel consists of a single PZT element, the beam former/pulser electronics, and the connecting wire, determining the number of elements that can be excited simultaneously.

What occurs during the demodulation process in ultrasound?

Demodulation converts electrical signals into a form suitable for display through rectification and smoothing.