Sun14November1246PM 7

Are the following true or false of ultrasound?

True / False

The Doppler effect describes the apparent change in velocity caused bythe movement of the object relative to the source Incorrect answer selected

A-mode ultrasound generates a two-dimensional image Correct

Is produced by the piezoelectric effect Correct

The frequency range of normal human hearing is between 15 Hz and 20,000 Hz Incorrect answer selected

The Doppler effect can be utilised to measure flow Correct

Explanation

The normal hearing range for an adult human is between 15 Hz and 20,000 Hz.

Ultrasound is produced by the piezoelectric effect of crystals when a voltage is applied across.

A two-dimensional image is produced by B-mode ultrasound, not an A-mode. An A-mode ultrasound displays the reflected ultrasound pulses from a single line scan and simply detects a range of tissue boundary. It is not particularly of use clinically.

The Doppler effect describes the apparent change in frequency caused by the movement of an object in relation to the source. It can be used to measure cardiac output (flow) in the oesophageal Doppler probe.

Reference:

Al-Shaikh B, Stacey S. Essentials of Anaesthetic Equipment. 3rd ed. London: Churchill Livingstone; 2008.

Davis PD, Kenny GNC. Basic Physics and Measurement in Anaesthesia. 5th ed. Edinburgh: Butterworth Heinemann; 2009.

Smith T, Pinnock C, Lin T. Fundamentals of Anaesthesia. 3rd ed. Singapore: Cambridge University Press; 2009.

Answer Statistics

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Average score: 63.04%

Times answered: 237