Ultrasound imaging, also called ultrasound scanning or sonogram, involves exposing the breast to high-frequency sound waves. A computer then calculates the distance to the reflecting or absorbing surface and then produces a two or three-dimensional image of the internal structures of the breast. Ultrasound exams do not use x-rays.
Breast ultrasounds are one of the tools used to find breast cancer. Another tool used to find breast cancer is the mammogram.
A video showing a breast ultrasound can be viewed here.