ARDMS (American Registry for Diagnostic Medical Sonography) Practice Test

What does Doppler ultrasound measure?

1. The size of tumors in the body

2. The change in frequency of sound waves due to motion

3. The amount of pressure in the arteries

4. The distribution of blood flow in the organs

The correct answer is: The change in frequency of sound waves due to motion

Doppler ultrasound measures the change in frequency of sound waves due to motion, making it a powerful tool for assessing blood flow and detecting abnormalities in the circulatory system. This phenomenon is based on the Doppler effect, where sound waves are compressed or stretched depending on whether the source of the sound is moving toward or away from the observer. In the context of medical imaging, this allows technologists and physicians to determine the speed and direction of blood flow, which is crucial for diagnosing conditions such as blockages, clots, and heart valve issues. While the ability to measure tumor size, assess blood pressure, and visualize blood distribution in organs are important aspects of medical imaging and diagnostics, they are not the primary functions of Doppler ultrasound. Instead, the key focus of this technique lies in evaluating the dynamic changes in frequency that occur with moving blood cells, thereby providing insights into cardiovascular health.