The machine sends a beam of radiation through your body. Your hard, dense bones block that beam, so they show up as white on the X-ray. The radiation also goes through softer tissue like muscle and fat, which appear in shades of gray on the X-ray. It allows the doctor to examine your bones. X-Rays of bone tumors are important in determining the differential diagnosis. The differential diagnosis is based on an X Ray. In terms of soft tissue tumors, X-Rays are important for determining if there is any mineralization (calcification or ossification) in the tumor that may help in categorizing and diagnosing the specific type of tumor. They also show if the underlying bone is eroded or involved in some manner.