Introduction to Radiation Safetyand Radiation Dosimetry

www.epa.gov

Basic dosimetry:Activity of Radioactive Source

alpha

beta

gamma

http://hyperphysics.phy-astr.gsu.edu http://library.thinkquest.org

Basic dosimetry:Absorbed Dose of Radiation

The Gray is a unit of absorbed radiation dose in terms of the energy actually deposited in the tissue.

The biologically effective dosein Sievert is the radiation dose multiplied by a "quality factor" which is an assessment of the effectiveness of that particular type and energy of radiation.

http://hyperphysics.phy-astr.gsu.edu

Meet the milliremA person would get this amount of radiation from• 3 days of living in Atlanta • 2 days of living in Denver • About 7 hours in some spots in the Espirito Santo State of Brazil.

You increase your dose by a millirem by: • an average year of TV watching • a year of wearing a luminous dial watch • a coast-to-coast airline flight • a year living next door to a normally operating nuclear power plant

Cohen, A. B., Before It's Too Late, Plenum Press, 1983.

No observable effect 0-25 Slight blood changes 25-100Significant reduction in blood platelets andwhite blood cells (temporary) 100-200 Severe blood damage, nausea, hair loss, hemorrhage, death in many cases 200-500Death in less than two months for over 80% >600

Acute Radiation Exposure (rem)

Nave, C. R. and Nave, B. C., Physics for the Health Sciences, 3rd Ed, W. B. Saunders, 1985.

Cosmic rays 45External radiation from radioactive ores, etc. 60Internal exposure from radioactive materialingested into the body 25 Diagnostic X-rays 70Total: 200

US Average Exposure (mrem/yr)

Bushong, Stewart C., Magnetic Resonance Imaging, 2nd Ed., Mosby-Year Book, Inc., 1996.

The maximum permissible occupational exposure for persons working in radiation related occupations is 5 rem per year.

Dose Calculations:energy loss by charged particles due to

Excitation and Ionization

Valence electron

Dose Calculations:Ionization energy loss rates vs. particle

momentum

http://www.cameco.com/uranium_101/fact.php

Stopping Radiation

Radiation from muons produced in cosmic rays

http://en wikipedia org/wiki/Gamma ray

Compton

Photoelectric effect

Pair production

Rev. Mod. Phys. 56, S1 - S299 (1984)

μ > μen

Radiation by electrons• Loss of energy due to ionization.• Loss of energy due to braking radiation

(Bremsstrahlung):

Purcell, Electricity and Magnetism

Electron

Proton

Radiation by electrons

Advanced Lab Radiation Safety Rules

μen/ρ(cm2/g)

The mass absorption coefficient for water vs. photon energy

Energy vs. range for electrons in aluminum.

Increased Cancer Risk:Bomb Victims

The increased risk of various types of cancer has been studied extensively among the victims of the Hiroshima and Nagasaki nuclear bombs. The study of 120,000 Japanese has led to the relative risk factors shown. The risk appears to be linear with dose. The dose at 1000 meters at Hiroshima is estimated at 4 grays.

Atlanta Journal, Mar 20,1993 pg F1.