ARDMS (American Registry for Diagnostic Medical Sonography) Practice Test

What is the typical frequency range used in diagnostic ultrasound?

1. 0.5 to 2 MHz

2. 2 to 18 MHz

3. 10 to 30 MHz

4. 20 to 40 MHz

The correct answer is: 2 to 18 MHz

The typical frequency range used in diagnostic ultrasound is 2 to 18 MHz. This range is optimal for various medical imaging applications, as it balances penetration depth and resolution. Higher frequencies, such as those found in the upper end of this range, produce better resolution images thanks to their shorter wavelengths. However, they have limited penetration abilities, which makes them suitable for imaging superficial structures like the thyroid or breast tissue. Conversely, lower frequencies provide deeper tissue penetration but result in lower resolution images, which is less desirable for the majority of diagnostic purposes in ultrasound. The frequencies chosen in the range of 2 to 18 MHz effectively meet the requirements for high-resolution images of both superficial and moderately deep tissues without sacrificing diagnostic quality. The other provided ranges fall outside of what is typically used for diagnostic purposes: 0.5 to 2 MHz is considered too low for most diagnostic imaging, while frequencies above 18 MHz may be used in specific applications such as ophthalmic ultrasound but are not standard for general diagnostic imaging across a variety of body systems.