Four Primary Types of Ionizing Radiation: Alpha Particles

Alpha Particles: 2 neutrons and 2 protonsThey travel short distances, have large massOnly a hazard when inhaled

Four Primary Types of Four Primary Types of Ionizing Radiation:Ionizing Radiation:

Alpha ParticlesAlpha Particles

Four Primary Types of Four Primary Types of Ionizing Radiation:Ionizing Radiation:

Beta ParticlesBeta ParticlesBeta Particles: Electrons or positrons having small mass and variable energy. Electrons form when a neutron transforms into a proton and an electron or:

Four Primary Types of Four Primary Types of Ionizing Radiation:Ionizing Radiation:

Gamma RaysGamma Rays

Gamma Rays (or photons): Result when the nucleus releases

Energy, usually after an alpha, beta or positron transition

Four Primary Types of Four Primary Types of Ionizing Radiation:Ionizing Radiation:

X-RaysX-Rays

X-Rays: Occur whenever an inner shell orbital electron is removed

and rearrangement of the atomic electrons results with the release of

the elements characteristic X-Ray energy

Four Primary Types of Four Primary Types of Ionizing Radiation:Ionizing Radiation:

NeutronsNeutrons

Neutrons: Have the same mass as protons but are uncharged

They behave like bowling balls

Four Primary Types of Four Primary Types of Ionizing RadiationIonizing Radiation

Alpha particlesBeta particlesGamma rays (or photons)X-Rays (or photons)Neutrons

RADIATION RADIATION FUNDAMENTALS FUNDAMENTALS

ATOMIC AND NUCLEAR ATOMIC AND NUCLEAR STRUCTURESTRUCTURE

Bureau of Radiation Control

Radioactivity: Elements & Radioactivity: Elements & AtomsAtoms

Atoms are composed of smaller particles referred to as:

– Protons

– Neutrons

– Electrons

Ionization Ionization Ionizing radiation is produced by unstable

atoms. Unstable atoms differ from stable atoms because they have an excess of energy or mass or both.

Unstable atoms are said to be radioactive. In order to reach stability, these atoms give off, or emit, the excess energy or mass. These emissions are called radiation.

Types or Products of Ionizing Types or Products of Ionizing RadiationRadiation

or X-

rayneutron

Ionizing Radiation

alpha particle

beta particle

Radioactive Atom

X-ray

gamma ray

Ionizing Radiation

alpha particle

beta particle

Radioactive Atom

X-ray

gamma ray

Direct Ionization Caused By:Direct Ionization Caused By:

Protons

Alpha Particles

Beta Particles

Positron Particles

Indirect Ionization Caused By:Indirect Ionization Caused By:

Neutrons

Gamma Rays

X-Rays

DNA and RadiationDNA and Radiation

Ionizing Radiation at the Ionizing Radiation at the Cellular LevelCellular Level

Causes breaks in one or both DNA strands or;

Causes Free Radical formation

Commonly Transported Commonly Transported RadioisotopesRadioisotopes

Americium-241= Diagnose thyroid disorders, smoke detectors.

Cesium-137= Cancer treatment.Iodine-125,131= Diagnosis & treatment

liver, kidney,heart, lung and brain.Technetium-99m=Bone and brain imaging;

thyroid and liver studies; localization of brain tumors.

Radiation MeasurementRadiation Measurement

Terminology:

– Exposure rate = amount radiation possible to receive per unit time.

– Dose = total amount of radiation received.

Radiation and Radioactivity: Radiation and Radioactivity: Units and QuantitiesUnits and Quantities

Department of HealthBureau of Radiation Control

Introduction Introduction

Quantities (mass, volume, time, etc.) vs. Units (grams, gallons, hours)

Units of exposure, radioactivity, and energy associated with ionizing radioactivity

As hours and minutes are to time ...

ObjectivesObjectives

Define – ROENTGEN, RAD, REM, CURIE, GRAY,

SIEVERT, BECQUEREL.– SI units vs. Standard English units

Discuss the use and conversion of unit prefixes

Transform units using “unit analysis”

Background Background

Early risk associated with use of ionizing radiation

skin erythema dose - 25yrs1928 - ROENTGEN introduced by ICRP

RoentgenRoentgen

RoentgenRoentgen

Pronounced rent’gen with a hard “g”Limitations

– only applies to photons– only applies in air– only applies to energies less than 3 MeV

Named after Wilhelm C. Roentgen (thus the abbr... is capital “R”)

radrad

radrad1 rad = 1 Roentgen

remrem

remrem

The unit of dose equivalent for any type of ionizing radiation absorbed by body tissue in terms of estimated biological effect - Unit of dose equivalent

Dose in health record is in units of rem1 rem = 1 Roentgen

Roentgen Equivalent Man

Quality Factor (Q)Quality Factor (Q)

The specific value that accounts for the ability of different types of ionizing radiation to cause varying degrees of biological damage– X-rays, gamma rays, & beta particles 1– Neutrons & High energy protons 10– Alpha Particles 20

Curie (Ci)Curie (Ci)

Radiation hazard does not solely depend on the activity. It also depends on the type of decay (alpha, beta, photon, etc.)

Named in honor of Pierre Curie

SI Radiation Protection UnitsSI Radiation Protection Units

Becquerel (Bq) for Curie– 1 Ci = 3.7 x 1010 Bq

Gray (Gy) for rad– 1 Gy = 100 rad

Sievert (Sv) for rem– 1 Sv = 100 rem

Unit AnalysisUnit Analysis

BASE UNIT CONVERSION TABLE

Unit Unit Conversion1 Bq 2.7 x 10-11 Ci1 Ci 3.7 x 1010 Bq

1 Bq 1 dis/sec1 dis/sec 2.7 x 10-11 Ci1 Ci 3.7 x 1010 dis/sec

Unit Analysis (Con’t.)Unit Analysis (Con’t.)BASE UNIT CONVERSION TABLE

Unit Unit Conversion

1 rem 0.01 Sv1 Sv 100 rem1 rad 0.01 Gy1 Gy 100 rad1 R 2.58 x 10-4 C/kg1 meter 3.28 ft (39.37in)

SummarySummary

Radiation Protection unit definitions (including SI units)

Unit PrefixesUnit conversions

Old TermsOld Terms

Roentgen-Based on the quantity of electrical charges produced in air by X or Gamma photons 1R=2 billion pr

RAD-Radiation Absorbed Dose is the work energy resulting from the absorption of one ROENTGEN or 6.24 E5 Mev

More Old TermsMore Old Terms

REM- Roentgen Equivalent Mammal is equal to the absorbed does in RADS multiplied by a quality factor

Quality FactorsBeta = 1

Gamma & X ray photons = 1Alpha = 10

Neutrons = 20

New Terms New Terms sort ofsort of

International Units have replaced the RAD and REM

GRAY (Gy) = 100 RADSIEVERT (Sv) = 100 REM

Same Quality Factors apply to the Sv

Units of RadioactivityUnits of Radioactivity

Curie (Ci) = 2.22 E12 dpm or 3.7E10 dpsBecquerel (Bq) = 1 dpsMaximum Dose/year = 5 REM or 50 mSvMaximum Dose/year for Declared Pregnant

Woman & Minors= 0.5 REM or 5 mSv

Half Life CalculationHalf Life Calculation

Annual Dose LimitsAnnual Dose LimitsExternal/Internal Exposure Limits for Occupationally Exposed Individuals

  Adult ($18 yrs) Minor (< 18 yrs)

Whole body* 5000 mrem/yr 500 mrem/yr

Lens of eye 15000 mrem/yr

1500 mrem/yr

Extremities 50000 mrem/yr

5000 mrem/yr

Skin 50000 mrem/yr

5000 mrem/yr

Organ 50000 mrem/yr

5000 mrem/yr

*Effective dose equivalent

Dose Response RelationshipsDose Response Relationships

0-150 rem—No or minimal symptoms150-400 rem—Moderate to severe illness400-800 rem—Severe illness deaths start

above 500 remAbove 800 rem—Fatal

***Acute whole body doses

Your Annual ExposureYour Annual ExposureActivity Typical DoseSmoking 280 millirem/year

Radioactive materials use  in a UM lab <10 millirem/year

Dental x-ray 10 millirem per x-ray

Chest x-ray  8 millirem per x-ray

Drinking water  5 millirem/yearCross country round trip by air  5 millirem per trip 

Coal Burning power plant 0.165 millirem/year 

Estimated Exposure To The Estimated Exposure To The National PopulationNational Population

Between 320 – 360 mr/yr

Another Look at SourcesAnother Look at Sources

Some Exposure LimitsSome Exposure Limits 2 mr/hr Dose rate to public / Federal 500 mr Emergency responder limit / State/BRC 5 r/yr Occupational /Federal 5 r/hr Turn back value / State/BRC 10 r Property / Federal 25 r Life saving / Federal >25r Volunteers only / Federal

Ref - 10CFR PART 20, EPA 400, FL-SOP

Security Security

All Radioactive Materials must be secured or under direct supervision at all times

There MUST be someone in the room at all times OR the door must be locked.

Spill ResponseSpill Response

On Skin—flush completelyOn Clothing—removeIf Injury—administer first aidRadioactive Gas Release—vacate area,

shut off fans, post warningMonitor all persons and define the area of

contamination

ALARAALARA

As Low As Reasonably Achievable—means making every reasonable effort to maintain exposures to radiation as far below the dose limits as is practicable consistent with the purpose for which the licensed activity is undertaken, taking into account the state of technology, the economics of improvements in relation to the state of technology, the economics of improvements in relation to benefits to the public health and safety, and other societal and socioeconomic considerations, and in relation to utilization of nuclear energy and licensed materials in the public interest.

Radiation ProtectionRadiation Protection

Decrease Time

Increase Distance

Increase Shielding