ARRT Ultrasound Practice Test

Circumference is the distance around the boundary of a circle. It’s the boundary length you’d measure if you traced around a circular object, and for a circle you can calculate it with C = 2πr or C = πd. Area, by contrast, measures how much surface is inside that boundary (for a circle, πr^2). Compression is about reducing volume or density, not the boundary length, and a cycle refers to a repeating process or sequence, not the distance around.