Final answer:
The sonographer can adjust the intensity of the ultrasound, which relates to the energy carried by the sound wave, to optimize image quality and ensure patient safety.
Step-by-step explanation:
In ultrasound imaging, a sonographer has control over certain parameters to optimize the quality of the diagnostic images. Among the options given, intensity is adjustable by the sonographer. It refers to the power per area and is related to how much energy the sound wave carries. Adjusting the intensity can help optimize image quality and is crucial for ensuring patient safety by avoiding excessive exposure to ultrasound energy.
Other aspects of ultrasound waves like propagation speed, period, and wavelength are inherent physical properties of the wave once it has been emitted. Specifically, the propagation speed is typically a constant in a given medium, the period is the inverse of the frequency (which the sonographer can choose before emission but cannot adjust once the wave is traveling), and wavelength is determined by both the propagation speed and the frequency.