ARDMS Ultrasound Physics & Instrumentation Practice Exam

What is the major component contributing to attenuation in ultrasound?

1. Frequency

2. Pulse repetition frequency

3. Propagation speed

4. Duty factor

The correct answer is: Pulse repetition frequency

The major component contributing to attenuation in ultrasound is frequency. In ultrasound imaging, attenuation refers to the decrease in the intensity of the ultrasound wave as it travels through a medium. This loss of intensity occurs due to absorption, reflection, and scattering of the sound waves, and these processes are heavily influenced by the frequency of the ultrasound. Higher frequency ultrasound waves are more prone to attenuation compared to lower frequency waves. This is because higher frequencies tend to have shorter wavelengths, which increases the likelihood of interaction with the tissues in the body, leading to greater absorption and scattering. As a result, higher frequency ultrasound will not penetrate as deeply into the tissue and will result in more rapid attenuation. In contrast, other choices such as pulse repetition frequency, propagation speed, and duty factor do not directly influence the attenuation of the ultrasound signal. Pulse repetition frequency relates more to the temporal resolution and frame rate of an ultrasound image rather than the attenuation characteristics. Propagation speed is a constant value determined by the medium through which the sound travels rather than a factor contributing to how much the sound wave loses energy. Lastly, duty factor pertains to the ratio of the pulse duration to the total time of the pulse cycle and does not directly impact the intrinsic attenuation properties of the ultrasound beam. Understanding