ARDMS Ultrasound Physics & Instrumentation Practice Exam

In clinical imaging, the typical range for wavelength measurement is:

1. 0.01 to 0.1 mm

2. 1 to 2 mm

3. 0.1 to 0.8 mm

4. 0.5 to 1.0 mm

The correct answer is: 0.1 to 0.8 mm

In clinical imaging, the wavelength of ultrasound waves is determined by the frequency of the sound waves and the speed of sound in the tissue being examined. The typical frequency range used in diagnostic ultrasound is between 2.5 MHz and 10 MHz, which directly influences the wavelength. For example, the wavelength can be calculated using the formula: wavelength = speed of sound / frequency. In soft tissue, the speed of sound is approximately 1540 m/s. When this speed is divided by the typical frequencies used in ultrasound, it results in wavelengths that fall within the range of approximately 0.1 to 0.8 mm. Therefore, this range reflects the wavelengths commonly utilized in clinical settings, offering a suitable balance between resolution and penetration. The choice that represents this typical measurement aligns well with the characteristics of ultrasound physics as applied in clinical imaging. This knowledge is essential for understanding image quality and the depth of tissue penetration, as different wavelengths correlate with various imaging parameters in clinical practice.