Radiation therapy uses high doses of radiation to destroy cancer cells. Ultrasound is used to guide the placement of radioactive beads or needles (brachytherapy) directly into the cancerous tissue.

The radioactive beads are left in place and gradually decay, releasing radiation at the site of the tumor over a few days or weeks.

Ultrasound uses reflected sound waves to produce an image of organs and other structures in the body. For this procedure, gel or oil is applied to the skin to help transmit the sound waves. A small handheld instrument called a transducer is passed back and forth over the area of the body being examined. The transducer sends out high-pitched sound waves (above the range of human hearing) that are reflected back to the transducer. A computer analyzes the sound waves and converts them into a picture the doctor uses to guide the placement of the beads or needles.