Radiation Safety Notes
Terrestrial radiation Natural background radiation that results from the presence of naturally
occurring radioactivity in the soil and earth
Cosmic radiation Natural background radiation that results from the interaction of particles
originating in outer space with the earth's atmosphere
Internal Radioactivity Natural background radiation due to naturally occurring radionuclides
that have been deposited in the human body via either ingestion or inhalation
300 millirem Average annual effective dose equivalent in the US (200 millirem attributed to
radon gas)
Medical radiation average per capita effective radiation dose equivalent is approximately53
millirem per year
DOT, OSHA, EPA, NRC, ICRP, NCRP Agencies responsible for radiation safety and control
5 rems per year Occupational Dose Limit for effective dose equivalent
15 rems per year Occupational Dose Limit for Lens of the eyes
50 rems per year Occupational Dose limit for any organ or tissue
.5 rem per gestation period Occupational dose limit for embryo/fetus of a declared pregnancy
.1 rem per year General Public dose limit for effective dose equivalent
As low as reasonably achievable ALARA acronym
Maintain radiation doses to personnel in medical institutions to 10% or less of the federal
limits of occupational exposure ALARA implementation
Personnel Dosimeters devices worn by individuals exposed to ionizing radiation to evaluate and
document their cumulative external radiation doses
Body Dosimeters utilize "optically stimulated luminescence (OSL)". Called "Luxel" dosimeters.
Very sensitive to ionizing radiation.
Ring Dosimeters are "thermoluminescent dosimeters (TLDs)". Used to measure doses to the
hands of certain personnel. Should be worn like a conventional ring.
Shallow dose, deep dose, lens dose three doses the luxel body dosimeter can report
Shallow dose dose equivalent computed for a tissue depth of 0.007 cm (skin dose)
Deep dose dose equivalent computed for a tissue depth of 1.0 cm
Lens dose dose equivalent computed for a tissue depth of .3 cm (thickness of the lens of each
eye)
Geiger-Muller instruments, Ionization Chamber survey instruments, Scintillation survey
instruments Three types of portable survey instruments
Geiger Muller Instruments
utilize a gas detector that is capable of detecting beta, gamma, and x-radiation. Uses mR/hr for
gamma and x, but uses counts per minute (cpm) for beta.
Ionization Chamber Survey Instruments
Measure radiation exposure in roentgens. CAn be used at higher exposure rate levels.
Considerably more expensive than Geiger
Scintillation Survey Instruments
utilize a solid sodium iodide crystal coupled to a sensitive photomultiplier tube as a detector.
Excellent at locating multiple sources or identifying areas of contamination
Recognizing sources of potential external exposure and controlling internal contamination
Good radiation hygiene
Time, Distance, and Shielding three cardinal principles for controlling external radiation
