Projectional radiography or diagnostic radiography is the practice of producing two-dimensional images using x-ray radiation. Radiographic exams are typically performed by Radiographers. Radiographers are trained, licesned medical professionals who specialize in the usage of radiographic positioning, patient care, selection of technical factors, radiographic equipment, and radiation safety. Projectional radiography is the cornerstone of modern medical imaging, and can be used to image almost every part of the human body. Mammography, DXA and dental radiography are specialized variants of projectional radiography. Computed tomography also uses x-radiation, but its different image acquisition parameters allow for images to be acquired in the axial plane.