High-intensity focused ultrasound, or HIFU, is an innovative, noninvasive treatment for prostate cancer as well as for pain caused by cancer that has spread to bones. The ultrasound transducer used for HIFU is similar to those used for diagnostic imaging but it emits sound waves of much higher intensity. Much as a magnifying glass can focus sunbeams to burn a hole in a piece of paper, the HIFU transducer focuses sound waves onto a tiny area of abnormal tissue, generating enough heat to destroy the cells. This treatment is also known as MRgFUS (MRI-guided focused ultrasound) and FUS (focused ultrasound surgery).