X-rays are waves of electromagnetic energy. X-rays are the most common and widely employed diagnostic imaging technique. X-rays produce a still picture of bones and organs. X-rays are especially useful in the detection of pathology of the skeletal system, but are also useful for detecting some disease processes in soft tissue. X-rays emitted from the instrument are blocked by dense tissues such as bone and these portions appear white on the image. Metal and special dye used to focus areas of the body will also appear white.