The radiographic image is formed by which of the following?

• A. Exit rays striking the image receptor
• B. Laser light
• C. Cosmic rays
• D. Electrons and heat

Answer: (A)

The image is formed when the exit rays strike the image receptor. After passing through the patient, the X-rays that emerge carry information about the varying densities of tissues. The receptor then converts the energy of those exit (remnant) rays into an image, whether on film or a digital detector. Laser light is used for reading or erasing storage phosphor plates in some systems, but it does not create the radiographic image during exposure. Cosmic rays don’t play a role in diagnostic radiography, and while electrons and heat in the X-ray tube generate the photons, the actual image results from the exit rays striking the receptor.