Chapter 2 – Principles of Radiation Biology and Radiation Protection

Radiation Protection for Patients

Patients should be appropriately shielded from direct and scattered radiation for all imaging examinations.

It is in the best interest of the patient and for the betterment of society that patients receive as little radiation as possible for diagnostic purposes.

The use of radiation should be justifiable i.e. the benefits outweigh the risks. Radiation dose should be minimized as best as possible without limiting the diagnostic utility of the examination. Attention should be paid to the cumulative amount of radiation that a patient is exposed to during healthcare encounters over the long term.


As defined in Title 10, Section 20.1003, of the Code of Federal Regulations (10 CFR 20.1003), ALARA is an acronym for “as low as (is) reasonably achievable,” which means making every reasonable effort to maintain exposures to ionizing radiation as far below the dose limits as practical, consistent with the purpose for which the licensed activity is undertaken, taking into account the state of technology, the economics of improvements in relation to state of technology, the economics of improvements in relation to benefits to the public health and safety, and other societal and socioeconomic considerations, and in relation to utilization of nuclear energy and licensed materials in the public interest. (5)