Chapter 2 – Principles of Radiation Biology and Radiation Protection



Our aim is to provide a focused discussion pertaining to diagnostic radiation usage and safety, with a focus on imaging modalities that use of x-rays.

Medical schools throughout the world emphasize radiological examination interpretation, but little is taught on the science behind these examinations and the potential harm from exposure to radiation.

We live in a world where everyone, and everything, is constantly exposed to non-ionizing and ionizing radiation. Ionizing radiation is electromagnetic energy that is capable of displacing electrons from the orbital rings of atoms, creating an ion. Ionizing radiation may arise from man-made activities or from natural sources. Natural sources of radiation include cosmic rays, isotopes in the ground, water, food (uranium, radium), or as a gas (radon).

X-rays for medical imaging:

It is generally accepted that patients are being exposed to more radiation today than in the past due to advances in imaging technologies and the broader application of imaging in healthcare. For example, there are many more indications for CT now than in the past i.e. CT pulmonary embolism studies and CT angiography for cardiac, cerebral, or peripheral arterial imaging.  Also, it seems that diagnosis and treatment are more intricately tied to the results of imaging examinations than in the past.

Alpha, beta, and gamma radiation emitted from within the patient due to the administration of a radioactive pharmaceutical is the second major type of radiation that patients will be exposed to. We will limit the focus our current discussion to x-rays generated for the acquisition of medical images.


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Introduction by Brent Burbridge is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License, except where otherwise noted.