X-rays are a type of electromagnetic radiation, just like visible light.
An x-ray machine sends individual x-ray particles through the body. The images are recorded on a computer or film.
- Structures that are dense (such as bone) will block most of the x-ray particles, and will appear white.
- Metal and contrast media (special dye used to highlight areas of the body) will also appear white.
- Structures containing air will be black, and muscle, fat, and fluid will appear as shades of gray.
Geleijns J, Tack D. Medical physics: radiation risks. In: Adam A, Dixon AK, Gillard JH, Schaefer-Prokop CM, eds. Grainger & Allison's Diagnostic Radiology: A Textbook of Medical Imaging. 6th ed. Philadelphia, PA: Elsevier Churchill Livingstone; 2015:chap 1.
Mettler FA Jr. Introduction: an approach to image interpretation. In: Mettler FA Jr, ed. Essentials of Radiology. 3rd ed. Philadelphia, PA: Elsevier Saunders; 2014:chap 1.