At sea level, the average cosmic radiation dose is about 26 mrem per year. Internal sources or sources found in the human bodyĬosmic radiation comes from the sun and outer space and consists of positively charged particles, as well as gamma radiation.Terrestrial radiation known as sources in the earth’s crust.The three major sources of naturally occurring radiation are:

There are many natural sources of radiation which have been present since the earth was formed.

The highest known level of background radiation in the world affecting a substantial population is in Kerala and the Madras States in India where some 140,000 people receive an annual exposure which averages over 30 mSv (3000 mrem) per year from both gamma and radon radiation (478% more than what is average in the US). For someone residing in the US, the annual background exposure is approximately 6.3 mSv (633 mrem), but some locations can be much higher. The unit of exposure or “dose” is often in mrems or mSvs (for more info see Stanford’s Radiation Safety Manual). We are also exposed through some medical treatments and through activities involving radioactive material.Īnnual background radiation is often used as a “baseline” exposure to compare occupational exposures (or even diagnostic imaging exposures such as chest x-rays) to what we are naturally exposed to in our everyday environment.īackground radiation consists of the radiation exposures received from both natural and man-made sources. People are constantly exposed to small amounts of ionizing radiation from the environment as they carry out their normal daily activities this is known as background radiation. Examples of non-ionizing radiation exposures in the clinical setting include Magnetic resonance imaging (MRI), ultrasound and LASERS. This is the type of radiation that people usually think of as “radiation.” These properties are taken advantage of in diagnostic imaging and to kill cancer cells.Įxamples of ionizing radiation uses are fluoroscopes, CT scanners and nuclear medicine bone scans. Radiation that falls within the “ionizing radiation” range has enough energy to remove tightly bound electrons from atoms, thus creating ions. Radiation that has enough energy to move atoms in a molecule around or cause them to vibrate, but not enough to remove electrons, is referred to as “non-ionizing radiation.” Examples of this kind of radiation are sound waves, visible light, and microwaves. Not all radiation interacts with matter in the same way. Last updated: OctoRadiation Protection Guidance For Hospital StaffĢ Introduction to Radiation Exposure 2.1 Types of Radiation Ionizing versus Nonionizingīecause health physics supports the uses of ionizing radiation it is helpful to discuss the reasons why this type of radiation is important. The Radiation Safety Officer is responsible for managing the radiation safety program subject to the approval of the Administrative Panel on Radiological Safety, and is authorized to take whatever steps are necessary to control and mitigate hazards in emergency situations.Ĭonsult with the Radiation Safety Officer at (650) 723-3201 for specific information. Our goal is to afford users as much flexibility as is safe and consistent with our policy of as low as reasonably achievable (ALARA) below the limits provided in the regulations. This guidance document provides an orientation on ionizing radiation, and describes radiation safety procedures we have implemented to ensure a safe environment for our patients and students, the public, and ourselves. Failure of any individual to comply with requirements can jeopardize the investigation, the laboratory, and the institution. All individuals who work with radioactive materials or radiation devices are responsible for knowing and adhering to applicable requirements. The privilege to use ionizing radiation at Stanford University, Stanford Health Care, Lucile Packard Children’s Hospital and Veterans Affairs Palo Alto Health Care System requires each individual user to strictly adhere to federal and state regulations and local policy and procedures.

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