What is the relationship between the frequency of ultrasound, depth of penetration, and resolution?
There is an inverse relationship between the frequency of the ultrasound probe and depth of penetration. Standard echoendoscopes typically have a frequency ranging from 5 to 10 mHz, which allows a depth of penetration of 8 and 4 cm, respectively. High-frequency ultrasound probes that can be passed through the biopsy channel of a standard gastroscope or colonoscope have higher frequencies up to 30 mHz with corresponding decreased depth of penetration. The higher the frequency, the greater the resolution (image clarity or ability to differentiate two adjacent objects).