For more than a century X radiation has been a valuable tool for imaging the human body. This imaging capability is used extensively to detect and diagnose disease and injury, manage patient care, and guide many forms of treatment.
Since each X ray procedure imparts energy with ionizing capability to the tissues of the body, specific action must be taken to minimize any associated risk to the patient by eliminating any radiation exposure that is not required for the formation of the images necessary for each clinical objective.
In all X ray imaging methods, the equipment operator controls the X ray beam that applies radiation to the patient. The characteristics of the X ray beam must be adjusted to optimize the critical balance between image quality and exposure to the patient. While there are several adjustable factors that have an effect on this balance, two of the most significant ones are tube voltage expressed in kilovolts (kV) and tube loading in mAs (also called 'product of the current intensity and exposure time'). The appropriate balance between the kV and mAs for an X ray examination is a major part of optimizing the procedure.
While there are some common principles of protection that apply to all X ray imaging procedures, many of the most significant issues and actions are related to the methods and modalities listed above.
For a description of radiation quantities and units used on these pages, please click here.