Radiation “Awareness”Radiation “Awareness”

ObjectivesObjectives

• To increase public understanding of To increase public understanding of radiation and radioactivityradiation and radioactivity

• To provide basic radiation-science To provide basic radiation-science information for use by science teachersinformation for use by science teachers

Health Physics SocietyHealth Physics SocietySpecialists in Radiation ProtectionSpecialists in Radiation Protection

OutlineOutline• Radiation theory & basicsRadiation theory & basics• Exposure and effectsExposure and effects• Ways to minimize exposureWays to minimize exposure• Beneficial uses in modern societyBeneficial uses in modern society• Resources and additional information Resources and additional information

Why Are Elements Why Are Elements Radioactive?Radioactive?

Unstable nucleus:Unstable nucleus:

• Has excess energy.Has excess energy.

• Wants to go to Wants to go to “ground state.”“ground state.”

• Becomes stable by Becomes stable by emitting ionizing emitting ionizing radiation.radiation.

What does “ionizing” mean?What does “ionizing” mean?

Who Discovered Who Discovered Radioactivity?Radioactivity?

Antoine Henri BecquerelAntoine Henri Becquerel

• Worked with uranium.Worked with uranium.• Noticed phosphorescence Noticed phosphorescence

caused film exposure after caused film exposure after leaving uranium in the leaving uranium in the sun.sun.

• Noticed same thing Noticed same thing happened on cloudy days. happened on cloudy days.

Alpha Particles (2n, 2p)

Beta Particles (e-or+)

Photons (hv)

(x or gamma rays)

Paper Concrete

Radiation TypesRadiation Types

Ionizing RadiationsIonizing RadiationsBeta DecayBeta Decay

3H

3He Ion

Beta particle

Anti Neutrino

N

PN

e

e

N

P P

The Electromagnetic SpectrumThe Electromagnetic Spectrum

Figure courtesy of NASA/JPL-CaltechFigure courtesy of NASA/JPL-Caltech

137mBa

Excited Nucleus

Gamma ray

137Ba

Ionizing Radiations Ionizing Radiations

Gamma EmissionGamma Emission

DefinitionsDefinitions• Radioactive decayRadioactive decay is a spontaneous process in which is a spontaneous process in which

nucleons are emitted from or transformed within the nucleons are emitted from or transformed within the nucleus, resulting in a change in the identity of the nucleus, resulting in a change in the identity of the nucleus, and usually accompanied by the emission of nucleus, and usually accompanied by the emission of one or more types of radiation from the nucleus and/or one or more types of radiation from the nucleus and/or atom.atom.

• Half-lifeHalf-life is the time required for half of the atoms of a is the time required for half of the atoms of a radioactive material to decay to another nuclear form.radioactive material to decay to another nuclear form.

Who’s the Famous “Madame” of Who’s the Famous “Madame” of Radiological Fame?Radiological Fame?

Marie CurieMarie Curie• With her husband With her husband

Pierre, discovered Pierre, discovered radium and coined radium and coined the term “radioactive”the term “radioactive”

• First woman to win First woman to win two Nobel Prizestwo Nobel Prizes

Units of RadioactivityUnits of Radioactivity

• The becquerel (Bq) The becquerel (Bq) or or • The curie (Ci)The curie (Ci) 1 Ci = 37,000,000,000 Bq1 Ci = 37,000,000,000 Bq so 1 mCi = 37 MBqso 1 mCi = 37 MBq and 1 µCi = 37 kBqand 1 µCi = 37 kBq

Approximate RadioactivityApproximate Radioactivityin Assorted Itemsin Assorted Items

Item or ProcessItem or Process mCi mCi MBq MBq

• Smoke DetectorSmoke Detector 0.001 0.001 0.037 0.037

• Biomedical Lab ExperimentBiomedical Lab Experiment 0.5 0.5 18.5 18.5

• Nuclear Medicine DoseNuclear Medicine Dose 10 10 370 370

• Industrial Radiography Source 40,000 1,480,000Industrial Radiography Source 40,000 1,480,000

Natural Background RadiationNatural Background Radiation

Man-Made RadiationMan-Made Radiation

Biological EffectsBiological EffectsMechanisms of InjuryMechanisms of Injury

Ionizing Radiation

Cell Death

Cell Damage

Repair Transformation

Radiation DoseRadiation Dose Dose or radiation dose is a generic term for a measure of radiation exposure. In radiation protection, dose is expressed in millirem.

X-Ray Machine Image

(film)Subject is not radioactive but has been exposed to a radiation dose (single chest x ray = 5-10 mrem).

After

External Dose

ContaminationContamination Contamination is the presence of a radioactive Contamination is the presence of a radioactive

material in any place where it is not desired, material in any place where it is not desired, and especially in any place where and especially in any place where

its presence could be harmful.its presence could be harmful.

Yuck!

Radiation Detection InstrumentsRadiation Detection Instruments

Geiger Counter Liquid Scintillation Counter

Photo by Karen Sheehan Photo by Carl Tarantino

Lessons from the PastLessons from the PastThe Radium Dial PaintersThe Radium Dial Painters

Photo by Carmelina Rattrovo from the Playwrights Theatre production of Radium Girls, by D.W. Gregory

Annual Radiation Dose LimitsAnnual Radiation Dose LimitsGeneral Public vs. OccupationalGeneral Public vs. Occupational

Established by the Established by the Nuclear Regulatory CommissionNuclear Regulatory Commission

• General Public Limit - 100 mrem General Public Limit - 100 mrem

• Occupational Limit - 5,000 mremOccupational Limit - 5,000 mrem

Remember – We get approximately 300 mrem per year from natural background Remember – We get approximately 300 mrem per year from natural background exposure.exposure.

Minimizing Radiation Minimizing Radiation ExposureExposure

Basic ConceptsBasic Concepts

• TimeTime• DistanceDistance• ShieldingShielding

Minimizing Exposure - TimeMinimizing Exposure - Time

• Minimize the Minimize the amount of time amount of time spent near spent near sources of sources of radiation.radiation.

Minimize Exposure by Minimize Exposure by Maximizing DistanceMaximizing Distance

As the distance from a radioactive source doubles, the exposure rate

decreases by a factor of four.

Minimizing Exposure By Minimizing Exposure By Using ShieldingUsing Shielding

Lead blanket Lead blanket shielding around shielding around letdown radiation letdown radiation monitorsmonitors

Surry Power Station

Loss of Life ExpectancyLoss of Life ExpectancyActivity or Behavior LLE (DAYS)__________________

Recreational swimming 40 Being 15 percent overweight 900 Smoking 20 cigarettes per day 1,600 Using pesticides at home 12 Being exposed to radon in a home 35

Living within 10 miles of a nuclear power plant 0.4 Riding a bicycle 6 Driving a car 200

Skydiving 25 Consuming alcohol (U.S. average) 230

Medicine and ResearchMedicine and Research

• Colleges

• Doctors’ Offices

• Hospitals

• Pharmaceutical

• Research and Development

Research: As a “Tracer”Research: As a “Tracer”

• Radioactivity is an excellent Radioactivity is an excellent tool!tool!

• Detectable in minute quantitiesDetectable in minute quantities

(like finding one grain of sand (like finding one grain of sand on a small beach containing on a small beach containing 6,000,000,000 granules)6,000,000,000 granules)

Power GenerationPower Generation

Nuclear power Nuclear power supplies 20 percent supplies 20 percent of energy in the of energy in the United States. United States. There are 104 There are 104 nuclear power nuclear power plants in the United plants in the United States.States. Photo by Karen Sheehan

Space ExplorationSpace Exploration

The fuel in:The fuel in:• SatellitesSatellites• Jupiter ProbeJupiter Probe• OthersOthers

Jupiter Probe

Who Discovered X Rays?Who Discovered X Rays?Wilhelm Conrad Wilhelm Conrad

RoentgenRoentgen

Roentgen worked with a Crookes tube to study cathode rays.

How X Rays WorkHow X Rays Work

X Rays (continued)X Rays (continued)

Other Types of X-Ray MachinesOther Types of X-Ray Machines

Photos by Karen Sheehan

X-Ray CrystallographyX-Ray Crystallography

Photo by Karen Sheehan

Nuclear MedicineNuclear MedicineDiagnostic ProceduresDiagnostic Procedures

• Radioactive injectionRadioactive injection• Short half-life Short half-life

radionuclide radionuclide • Pictures taken with Pictures taken with

special gamma cameraspecial gamma camera• Many different studies:Many different studies:

ThyroidThyroidLungLungCardiac Cardiac White Blood CellWhite Blood Cell Photo by Karen Sheehan

Bone ScansBone Scans

Image courtesy of

Radiation TherapyRadiation TherapyUsed for treating cancer. Why does it work? Used for treating cancer. Why does it work?

External Beam Brachytherapy (implants)

Image courtesy of

Photo by Karen Sheehan

Radioactive Consumer ProductsRadioactive Consumer Products

Photo by Karen Sheehan

For more information For more information about radiation you may about radiation you may

contact the Health contact the Health Physics Society.Physics Society.

http://www.HPS.orgHealth Physics Society

Specialists in Radiation Safety

Additional ReferencesAdditional References

• Hall E. Radiation and life, 2Hall E. Radiation and life, 2ndnd ed. ed. New York: Pergamon Press; 1984.New York: Pergamon Press; 1984.

• Bushong SC. Radiologic science for Bushong SC. Radiologic science for technologists, 7technologists, 7thth ed. St Louis, MO: Mosby, ed. St Louis, MO: Mosby, Inc.; 2001.Inc.; 2001.