radiation safety. definitions roentgen roentgen – 2.58 x10 4 coulombs/kg air rad rad – radiation...

RADIATION SAFETYRADIATION SAFETY

DefinitionsDefinitions RoentgenRoentgen

– 2.58 x102.58 x1044 coulombs/kg air coulombs/kg air RAD RAD

– Radiation Absorbed Dose- Density Radiation Absorbed Dose- Density dependant (to convert roentgens to dependant (to convert roentgens to rads you must include a density rads you must include a density factor)factor)

REMREM– Roentgen Equivalent Man Roentgen Equivalent Man

REMREM

RAD * Q factor = REMRAD * Q factor = REM GRAY * Q factor = SievertGRAY * Q factor = Sievert

DefinitionsDefinitions Gray = 100 RADGray = 100 RAD Sievert = 100 REMSievert = 100 REM

DefinitionsDefinitions Curie = 3.7 * 10Curie = 3.7 * 101010 dps dps

– cps vs dpscps vs dps Becquerel = 1 dpsBecquerel = 1 dps

DefinitionsDefinitions Linear Energy Transfer (LET)Linear Energy Transfer (LET)

– Energy given up per unit distance Energy given up per unit distance traveledtraveled

Specific Ionization (SI)Specific Ionization (SI)– Ion pairs formed per distance Ion pairs formed per distance

traveledtraveled– Note a high LET or SI gives greater Note a high LET or SI gives greater

radiotoxicityradiotoxicity

LET or SILET or SI

++

+ +

+

+_

_

_

_

_

_

DefinitionsDefinitions Background RadiationBackground Radiation

– 1-2 msieverts/year1-2 msieverts/year Erythema DoseErythema Dose

– 1 gray to the skin1 gray to the skin LD50LD50

– 5 gray whole body exposure5 gray whole body exposure

DefinitionsDefinitions ALARAALARA

– As Low As Is Reasonably AchievableAs Low As Is Reasonably Achievable– Because we don’t Because we don’t

know know

ALARA ContinuedALARA Continued

While the regulatory limit is 50 While the regulatory limit is 50 msievert per year (about 12.5 msievert per year (about 12.5 msievert/quarter) At BYU I will msievert/quarter) At BYU I will investigate any quarterly dose investigate any quarterly dose above 100 mrem (1 msievert)above 100 mrem (1 msievert)

DefinitionsDefinitions Gamma ray Gamma ray

– Origin NucleusOrigin Nucleus– Low mass, charge Low mass, charge – Low LETLow LET

DefinitionsDefinitions X-ray just like gamma but origin X-ray just like gamma but origin

is an electronis an electron Beta ParticlesBeta Particles

– Mass and charge = electronMass and charge = electron– high LEThigh LET

KERMA = kenitic energy released KERMA = kenitic energy released per unit massper unit mass

DefinitionsDefinitions Electron captureElectron capture Beta DecayBeta Decay Alpha DecayAlpha Decay

DefinitionsDefinitions

Total Effective Dose EquivalentTotal Effective Dose Equivalent Cumulative Committed Effective Cumulative Committed Effective

Dose EquivalentDose Equivalent Deep Dose EquivalentDeep Dose Equivalent

Biological EffectsBiological Effects AcuteAcute ChronicChronic

Biological EffectsBiological Effects

Direct chemical damage due to Direct chemical damage due to ionization of important biological ionization of important biological moleculesmolecules

Most damage is done by radical Most damage is done by radical formation – the most common is formation – the most common is the hydroxyl radicalthe hydroxyl radical

HH22O + radiation O + radiation >> H H+ + + OH + OH (unpaired electron)(unpaired electron)

Biological EffectsBiological Effects AcuteAcute

Biological EffectsBiological Effects Erythema (skin gets red) 1 grayErythema (skin gets red) 1 gray Bone Marrow and white blood cells Bone Marrow and white blood cells

destroyed (about 5 gray or 500 RAD) destroyed (about 5 gray or 500 RAD) this is the LD50. Ionizing radiation is a this is the LD50. Ionizing radiation is a “metabolic poison” it preferentially “metabolic poison” it preferentially damages rapidly metabolizing cells.damages rapidly metabolizing cells.

Gi tract -10 to 20 gray whole body Gi tract -10 to 20 gray whole body (death certain)(death certain)

CNS is destroyed at 50 gray and aboveCNS is destroyed at 50 gray and above

Biological EffectsBiological Effects ChronicChronic

Biological EffectsBiological Effects CancerCancer MutationsMutations TeratogensTeratogens

Biological EffectsBiological Effects DNA DamageDNA Damage RNA DamageRNA Damage Enzyme DamageEnzyme Damage

NOTE: Damage to DNA is NOTE: Damage to DNA is amplified through transcription amplified through transcription and replicationand replication

Dose Response

0

5

10

15

20

0 0.5 1 1.5

Exposure (sieverts)

exce

ss c

ance

rs (

life

tim

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Series1

Biological EffectsBiological Effects Linear No Threshold Theory states that Linear No Threshold Theory states that

if the dose is doubled the risk of toxic if the dose is doubled the risk of toxic effects (due to ionizing radiation) is effects (due to ionizing radiation) is doubleddoubled– Not definitively demonstrated at low dosesNot definitively demonstrated at low doses– Not applicable to acute dose, applicable to Not applicable to acute dose, applicable to

stochastic or random events like cancerstochastic or random events like cancer– Always RBE (rem or sievert)Always RBE (rem or sievert)

Biological EffectsBiological Effects Internal vs External Hazard Internal vs External Hazard

(epithelial barrier)(epithelial barrier) Some nuclides can only hurt you Some nuclides can only hurt you

if they get inside you. Examples if they get inside you. Examples low energy beta emitters such as low energy beta emitters such as 3535S, S, 33H, H, 1414C and alpha emittersC and alpha emitters

RadiotoxicityRadiotoxicity– LET, Target Organ, Effective Half LifeLET, Target Organ, Effective Half Life

Interactions (Photons)Interactions (Photons) Compton scattering Compton scattering Photoelectric effectPhotoelectric effect Pair ProductionPair Production Half Value LayerHalf Value Layer

Interactions (Beta Interactions (Beta Particles)Particles) BremsstraahlungBremsstraahlung IonizationIonization RangeRange

Interactions (Beta Interactions (Beta Particles)Particles) Bremsstraahlung (x-rays)Bremsstraahlung (x-rays)

– Increased by high atomic number Increased by high atomic number materialsmaterials

– Increased by high energy electronsIncreased by high energy electrons

Nuclide CharacteristicsNuclide Characteristics

Tritium Tritium 33HH Very Low energy –Beta emitterVery Low energy –Beta emitter Cannot be detected with Geiger Cannot be detected with Geiger

CounterCounter LSC and Gas proportional countersLSC and Gas proportional counters 12 year half-life12 year half-life 6 keV6 keV

Nuclide CharacteristicsNuclide Characteristics

35S and 14C35S and 14C Low Energy BetaLow Energy Beta 10 percent 2pi efficiency10 percent 2pi efficiency 87 day half-life87 day half-life 50 keV, range in air 22 cm50 keV, range in air 22 cm

Nuclide CharacteristicsNuclide Characteristics

32P32P High energy – bremsstraahlungHigh energy – bremsstraahlung GM detector gives high efficiencyGM detector gives high efficiency 14.29 days half life14.29 days half life 700 keV energy, range in air 6 700 keV energy, range in air 6

metersmeters LET is inversely proportional to LET is inversely proportional to

energy energy

Nuclide CharacteristicsNuclide Characteristics

• 125I 125I • Gamma emitter low energy Gamma emitter low energy

(electron capture)(electron capture)• Target organ – thyroidTarget organ – thyroid• 60 day half-life60 day half-life• Solid scintillation is best detection Solid scintillation is best detection

methodmethod

Nuclide CharacteristicsNuclide Characteristics

33P Low energy beta emitter 27 33P Low energy beta emitter 27 day half lifeday half life

14C low energy beta emitter 5000 14C low energy beta emitter 5000 year half lifeyear half life

Waste DisposalWaste Disposal DecayDecay SewerSewer ShipShip

ChemicalsChemicals

Management 2-6156 Management 2-6156 (characterization)(characterization)

Waste DisposalWaste Disposal DecayDecay

– Half life less than 90 daysHalf life less than 90 days– Remove all labelsRemove all labels

Waste DisposalWaste Disposal SewerSewer

– 100 microcuries of tritium100 microcuries of tritium– 100 microcuries of 35S100 microcuries of 35S– 100 microcuries of 14 C100 microcuries of 14 C– 100 microcuries of 32P100 microcuries of 32P– No IodineNo Iodine

Waste Disposal Waste Disposal Remove all labelsRemove all labels List NuclideList Nuclide Note quantityNote quantity

Waste DisposalWaste Disposal Liquids must be in Plastic leak Liquids must be in Plastic leak

proof containersproof containers Solids should be in a closed Solids should be in a closed

plastic bagplastic bag List laboratoryList laboratory

Waste DisposalWaste Disposal Never mix hazardous chemical Never mix hazardous chemical

wastes with radioactive wastes wastes with radioactive wastes without RSO Approvalwithout RSO Approval

Never mix short half life nuclides Never mix short half life nuclides with long half life nuclides without with long half life nuclides without RSO approvalRSO approval

Get approval from the RSO before Get approval from the RSO before using radioactive isotopes in using radioactive isotopes in animalsanimals

DosimetryDosimetry TLD badges for TLD badges for

external hazard external hazard materialsmaterials

Significant Significant Quantities Quantities – Over 2 millicuries Over 2 millicuries

in one packagein one package– Over 3 millicuries Over 3 millicuries

in one monthin one month

DosimetryDosimetry

Thermoluminescent DosimetryThermoluminescent Dosimetry– Heat Heat

Wear the badge on or near your Wear the badge on or near your lapellapel

Wear ring badge with TLD crystal Wear ring badge with TLD crystal to the inside (exposed) portion of to the inside (exposed) portion of your handyour hand

Wear fetal badge near stomachWear fetal badge near stomach

IodinationsIodinations E 238 BNSN E 238 BNSN Perform thyroid assay before, Perform thyroid assay before,

following and 24 hrs laterfollowing and 24 hrs later Use RSO’s survey meterUse RSO’s survey meter Keep results in your book and Keep results in your book and

send them to the RSOsend them to the RSO

BioassayBioassay

If you handle 5 mCi or more you If you handle 5 mCi or more you will do bioassayswill do bioassays

Bioassays required for all Bioassays required for all iodinationsiodinations– Solid ScintillatorSolid Scintillator– Urine (early morning – 1 ml count Urine (early morning – 1 ml count

one minute)one minute)

Leak CheckLeak Check All new material should be leak All new material should be leak

checked prior to usechecked prior to use Call the RSO if a leak is detectedCall the RSO if a leak is detected

ProtectionProtection Time, Distance, Shielding and Time, Distance, Shielding and

QuantityQuantity Use Personal Protective Use Personal Protective

EquipmentEquipment– Gloves, goggles, lab coatGloves, goggles, lab coat

Eating and DrinkingEating and Drinking Never eat, drink or apply makeup Never eat, drink or apply makeup

in a laboratory authorized for use in a laboratory authorized for use of radioactive isotopesof radioactive isotopes

RegulationsRegulations R313-15 and R313-18, 10 CFR 20, R313-15 and R313-18, 10 CFR 20,

LicenseLicense Allowable Exposure 5 Rem/YearAllowable Exposure 5 Rem/Year Pregnancy 500 Pregnancy 500

mrem/pregnancymrem/pregnancy

RegulationsRegulations

The University has an obligation to The University has an obligation to the pregnant woman and her the pregnant woman and her unborne baby. But this obligation unborne baby. But this obligation begins with a formal (written) begins with a formal (written) declaration of the pregnancy.declaration of the pregnancy.

RegulationsRegulations SecuritySecurity

– Locked Up –double locksLocked Up –double locks– Under personal supervision of an Under personal supervision of an

authorized individualauthorized individual

RegulationsRegulations

Required NoticeRequired Notice– DRC04 must be postedDRC04 must be posted– Dosimetry Report annually.Dosimetry Report annually.

InstrumentationInstrumentation Ionization ChamberIonization Chamber Gas proportional counterGas proportional counter Geiger Mueller counterGeiger Mueller counter

Laboratory SurveysLaboratory Surveys Survey your laboratory each day Survey your laboratory each day

that isotopes are in usethat isotopes are in use Log the survey valuesLog the survey values Identify the survey meter and Identify the survey meter and

personperson

InstrumentationInstrumentation

_ +

Gas Filled Chamber

Electronics

+ _+ _

+ _

InstrumentationInstrumentation Solid ScintillatorSolid Scintillator

– Most sensitive for photons (required Most sensitive for photons (required if you use 125I)if you use 125I)

Liquid ScintillationLiquid Scintillation– 4 4 ππ geometry geometry– Tritium detectionTritium detection

InstrumentationInstrumentation EfficiencyEfficiency

– Geometry - surface area of a sphere Geometry - surface area of a sphere =4=4ππ r r22

– CoincidenceCoincidence– WindowWindow

InstrumentationInstrumentation

Calibration must be completed at Calibration must be completed at least annually.least annually.– Photon detectors must be sent outPhoton detectors must be sent out– Beta survey instruments may be Beta survey instruments may be

calibrated by Risk Managementcalibrated by Risk Management

Laboratory SurveysLaboratory Surveys

Check hands, telephone, bench, Check hands, telephone, bench, floor in front of bench, soles of floor in front of bench, soles of shoes, computer keyboard, shoes, computer keyboard, centrifuges, door handlecentrifuges, door handle

Survey at the end of each day Survey at the end of each day that rad material is used.that rad material is used.

Be prepared to calculate surface Be prepared to calculate surface contaminationcontamination

Laboratory SurveysLaboratory Surveys

DocumentationDocumentation– DateDate– Instrument SNInstrument SN– Battery checkBattery check– Check Source countCheck Source count– ID of person completing the surveyID of person completing the survey– Survey resultSurvey result– Anything above background is Anything above background is

positivepositive

Laboratory SurveysLaboratory Surveys

Important variablesImportant variables– Nuclide energyNuclide energy– Distance from the surfaceDistance from the surface– Speed of detector movementSpeed of detector movement– Audible is more sensitive than Audible is more sensitive than

instrument readinginstrument reading

DocumentationDocumentation Receipt logsReceipt logs Disposal logsDisposal logs Survey logsSurvey logs

DocumentationDocumentation CertificationCertification User AuthorizationUser Authorization Facility AuthorizationFacility Authorization Training listTraining list

EmergenciesEmergencies Call 2-2222 if no risk of life or Call 2-2222 if no risk of life or

healthhealth Call 911 if risk of life or healthCall 911 if risk of life or health

Emergency ProceduresEmergency Procedures

Get Help - Emergencies call 911 Get Help - Emergencies call 911 on a campus phone on a campus phone

If help is needed immediately call If help is needed immediately call 2-22222-2222

Radiation Safety Officer 2-4468Radiation Safety Officer 2-4468

Emergency ProceduresEmergency Procedures

First priority Human life and safetyFirst priority Human life and safety Second priority limit the spread Second priority limit the spread

(consistent with first priority)(consistent with first priority)– Clean the spill upClean the spill up– Block off the areaBlock off the area– Survey for contamination on yourself Survey for contamination on yourself

and the ‘clean areas around you’ pay and the ‘clean areas around you’ pay particular attention to your shoes. particular attention to your shoes.