ARDMS Ultrasound Physics & Instrumentation Practice Exam

What is the typical range of frequency for diagnostic ultrasound imaging?

1. 0.1 to 1 MHz

2. 1 to 20 MHz

3. 20 to 50 MHz

4. 50 to 100 MHz

The correct answer is: 1 to 20 MHz

The typical range of frequency for diagnostic ultrasound imaging is between 1 to 20 MHz. This frequency range is commonly used because it strikes a balance between resolution and penetration. Frequencies toward the lower end (around 1 MHz) provide deeper tissue penetration, making them suitable for imaging structures that are located deeper in the body. However, they do sacrifice some image resolution. Conversely, higher frequencies (up to 20 MHz) offer better resolution and detail, which is advantageous for imaging superficial structures but have limited penetration. Using frequencies higher than 20 MHz can lead to decreased penetration and are generally employed in specialized situations such as dermatologic imaging or certain vascular applications. Frequencies below 1 MHz are typically outside the realm of diagnostic ultrasound and more aligned with therapeutic ultrasound applications, which require lower frequencies to deliver energy effectively. Therefore, the chosen range of 1 to 20 MHz is optimal for a wide variety of diagnostic imaging scenarios, ensuring both adequate detail and depth of visualization.