Radiation may be defined as energy traveling through space. Non-ionizing radiation is essential to life, but excessive exposures will cause tissue damage. All forms of ionizing radiation have sufficient energy to ionize atoms that may destabilize molecules within cells and lead to tissue damage. http://www.osha.gov/SLTC/radiation/

http://www.epa.gov/radiation/

http://www.radiologyinfo.org/en/safety/index.cfm?pg=sfty_xray

http://www.acr.org/SecondaryMainMenuCategories/MeetingsandEvents/acr_meetings/AMCLC-RO-Course.aspx

http://www.acr.org/