Ultrasound Imaging: Understanding the Difference between AIUM 100 mm Test Object and Tissue Equivalent Phantom

What is the major distinction between an AIUM 100 mm test object and a tissue equivalent phantom?

1) Gray scale can be better assessed with the use of a tissue equivalent phantom

2) The speed of sound in the tissue equivalent phantom and the AIUM 100 mm test object are the same

3) The attenuation of sound in the tissue equivalent phantom is less than that in the AIUM 100 mm test object

4) The speed of sound in a tissue equivalent phantom exceeds the speed of sound in an AIUM 100 mm test object

5) Color angio Doppler can be better assessed with a tissue equivalent phantom

Answer:

The difference between an AIUM 100 mm test object and a tissue equivalent phantom lies in the acoustic properties; tissue equivalent phantoms better resemble human tissue for ultrasound imaging.

Ultrasound Physics and Tissue Imaging:

The major distinction between an AIUM 100 mm test object and a tissue equivalent phantom is that a tissue equivalent phantom is designed to more accurately mimic the acoustic properties of human tissues, specifically the speed of sound and the attenuation of sound. While the AIUM test object provides a consistent medium for testing resolution and depth calibration of ultrasound equipment, the tissue equivalent phantom reflects the behavior of ultrasound in the human body more closely. Therefore, gray scale and color Doppler imaging can be better assessed with a tissue equivalent phantom because it represents the interaction of sound waves within biological tissue more realistically.

Regarding the physics of ultrasound imaging, the difference in echo times for tissues at different depths can help determine the scanner's ability to resolve small details. Also, the minimum frequency of ultrasound for effective imaging should correspond to the period being less than or equal to the minimum time resolution. Standard diagnostic ultrasound frequencies range from about 2 to 15 MHz, depending on the depth of penetration and resolution required.

In practice, due to the accepted limits determined by the ultrasound frequency and the depth of tissue penetration, there is a trade-off between resolution and penetration depth. Higher-frequency ultrasound waves, which can provide better resolution, do not penetrate as deep as lower frequencies. Current technology allows for about 1-mm detail at frequencies commonly used in abdominal scans, such as 7 MHz, with a standard penetration depth.