Ionizing radiation from medical imaging. Average man-made exposure is much higher in developed countries, mostly due to CT scans and nuclear medicine. Natural background radiation comes from five primary sources: cosmic radiation, solar radiation, external terrestrial sources, radiation in the human body, and radon. The background rate for natural radiation varies considerably with location, being as low as 1.5 mSv/a (1.5 mSv per year) in some areas and over 100 mSv/a in others. The highest level of purely natural radiation recorded on the Earth's surface is 90 µGy/h (0.8 Gy/a) on a Brazilian black beach composed of monazite. The highest background radiation
Treatment of infections after exposure to ionizing radiation in humans are available, almost all of the current information is based on animal research. Infections caused by ionizing radiation can be endogenous, originating from the oral and gastrointestinal bacterial flora, and exogenous, originating from breached skin following trauma. The organisms causing endogenous infections are generally gram negative bacilli such as Enterobacteriaceae (i.e. "Escherichia coli, Klebsiella pneumoniae, Proteus" spp. ), and "Pseudomonas aeruginosa." Exposure to higher doses of radiation is associated with systemic anaerobic infections due to gram negative bacilli and gram positive cocci. Fungal infections can also emerge in those that fail antimicrobial therapy and stay febrile for over