Each step up multiplies by 10. Each step down divides by 10.
A shorthand for very large or small numbers. Write a number between 1 and 10, then multiply by a power of 10.
The decimal moved 3 places left → exponent is positive 3.
The decimal moved 2 places right → exponent is negative 2.
Positive exponent = big number (decimal moved left).
Negative exponent = small number (decimal moved right).
Four prefixes you will use constantly in sonography physics.
Ultrasound lives in the Megahertz range. A 12 MHz transducer reveals exquisite surface detail. A 2 MHz transducer reaches deep into the body. The tradeoff between resolution and penetration is the central tension of your craft.
Axial resolution is measured in fractions of a millimeter. It determines whether your image shows two structures or smears them into one.
The kilohertz range governs Pulse Repetition Frequency and Doppler shift. When you track a thousand pulses per second to watch blood move, you are counting at the kilo scale.
A microsecond is the period of one ultrasound wave cycle at 1 MHz. Double the frequency and the period halves to 0.5 μs. Pulse duration, spatial pulse length, and duty factor are all measured at this scale.
Test your understanding of metric prefixes.