An X-Ray of the Mastoid (Lat View) is a diagnostic imaging test that uses low levels of radiation to produce images of the mastoid bone, which is located behind the ear.This test may be performed to diagnose or evaluate conditions that affect the mastoid bone, such as infections, tumors, or fractures. It can help identify the presence and location of any abnormalities within the mastoid bone, as well as assess the extent and severity of any damage or disease.