Ionizing & Non-ionizing Ionizing & Non-ionizing RadiationRadiation

ENGR 4410 – INDUSTRIAL HYGIENE ENGR 4410 – INDUSTRIAL HYGIENE

INSTRUMENTATIONINSTRUMENTATION

October 23, 2013October 23, 2013 Janet M. Gutiérrez, DrPH, CHP, RRPTJanet M. Gutiérrez, DrPH, CHP, RRPT

Radiation Safety Program ManagerRadiation Safety Program Manager

Environmental Health & SafetyEnvironmental Health & Safety

713-500-5844713-500-5844

Janet.R.McCrary@uth.tmc.eduJanet.R.McCrary@uth.tmc.edu

Speaker BiographySpeaker Biography

Janet M. Gutierrez is manager of the Radiation Janet M. Gutierrez is manager of the Radiation Safety Program at The University of Texas Health Safety Program at The University of Texas Health Science Center at Houston. She is a Certified Science Center at Houston. She is a Certified Health Physicist (CHP) and a Registered Radiation Health Physicist (CHP) and a Registered Radiation Protection Technologist (RRPT). In August 2011, Protection Technologist (RRPT). In August 2011, she received a Doctorate in Public Health from the she received a Doctorate in Public Health from the The University of Texas at Houston School of Public The University of Texas at Houston School of Public Health (UT SPH), and in 2005, she received a M.S. Health (UT SPH), and in 2005, she received a M.S. in Environmental Sciences / Industrial Hygiene from in Environmental Sciences / Industrial Hygiene from UT SPH as well. In 1998, Janet received a B.S. in UT SPH as well. In 1998, Janet received a B.S. in Radiological Health Engineering from Texas A&M Radiological Health Engineering from Texas A&M University in College Station, TX.University in College Station, TX.

Speaker BiographySpeaker Biography

Travis Halphen is a Safety Specialist in the Travis Halphen is a Safety Specialist in the Radiation Safety Program at The University of Radiation Safety Program at The University of Texas Health Science Center at Houston (UTHSC-Texas Health Science Center at Houston (UTHSC-H). He is currently seeking his MPH in H). He is currently seeking his MPH in Environmental Health and Occupational Safety from Environmental Health and Occupational Safety from University of Texas School of Public Health (UT University of Texas School of Public Health (UT SPH) and on May 2006 he received a Bachelors in SPH) and on May 2006 he received a Bachelors in Medical Physics from Louisiana State University. Medical Physics from Louisiana State University. He was Assistant Radiation Safety Officer and Laser He was Assistant Radiation Safety Officer and Laser Safety Officer at Kansas State University from 2006 Safety Officer at Kansas State University from 2006 to 2008 before he ended up at his current position at to 2008 before he ended up at his current position at UTHSC-HUTHSC-H

Ionizing vs. Non-ionizing Ionizing vs. Non-ionizing RadiationRadiation Electromagnetic SpectrumElectromagnetic Spectrum

RadiationRadiation

Ionizing & Non-ionizing Ionizing & Non-ionizing RadiationRadiation UnitsUnits DecayDecay Inverse Square LawInverse Square Law Shielding, HVL, TVLShielding, HVL, TVL InstrumentsInstruments DosimetryDosimetry Biological EffectsBiological Effects RegulationsRegulations Practice ProblemsPractice Problems

TypesTypes Biological EffectsBiological Effects Regulations/GuidesRegulations/Guides

What is Radiation?What is Radiation?

Radiation is energy transmitted by particles Radiation is energy transmitted by particles or electromagnetic wavesor electromagnetic waves

Radiation can be ionizing or non-ionizingRadiation can be ionizing or non-ionizing

Basic ConceptsBasic Concepts Radiation: energyRadiation: energy Ionizing vs. Non-Ionizing: enough energy to Ionizing vs. Non-Ionizing: enough energy to

eject orbital electrons eject orbital electrons Radioactivity: excess nuclear energyRadioactivity: excess nuclear energy

RadioactivityRadioactivity

Radioactivity is the natural property of certain Radioactivity is the natural property of certain nuclides to spontaneously emit energy, in the nuclides to spontaneously emit energy, in the form of ionizing radiation, in an attempt to form of ionizing radiation, in an attempt to become more stable.become more stable.

Basic ConceptsBasic Concepts

Radionuclide Radionuclide NuclideNuclide Isotopes have the same Z and a different A; Isotopes have the same Z and a different A;

1010C,C,1111C, C, 1212C, C, 1313C, C, 1414C C

Isobars have the same A and a different Z; Isobars have the same A and a different Z; 1414N, N, 1414O; O; 1515N, N, 1515CC

Isomers have the same A and the same Z; Isomers have the same A and the same Z; 99m99mTc, Tc, 9999Tc Tc

Isotones have the same N and a different A; Isotones have the same N and a different A; 1414O,O,1313N,N,1212C,C,1111B,B,1010Be,Be,88Li Li

Basic ConceptsBasic Concepts Types of radiation:Types of radiation:

Alpha: particulate, Alpha: particulate, massivemassive

Beta: particulate, Beta: particulate, penetratingpenetrating

Gamma: Gamma: electromagnetic, electromagnetic, penetratingpenetrating

X-ray: electromagnetic, X-ray: electromagnetic, penetratingpenetrating

Neutron: particulate, no Neutron: particulate, no chargecharge

Alpha (Alpha (αα))

Needs at least 7.5 MeV energy to penetrate Needs at least 7.5 MeV energy to penetrate nominal protective layer of skin (7 mg/cmnominal protective layer of skin (7 mg/cm22)) Most Most αα less than this energy, so can not penetrate less than this energy, so can not penetrate

skinskin Range in airRange in air Range (cm) = 0.56E for E< 4 MeVRange (cm) = 0.56E for E< 4 MeV Range (cm) = 1.24E-2.62 for E> 4 MeVRange (cm) = 1.24E-2.62 for E> 4 MeV

Beta (Beta (ββ))

Need at least 70 keV energy for beta to penetrate Need at least 70 keV energy for beta to penetrate nominal protective layer of skinnominal protective layer of skin

ββaveave = 1/3 = 1/3 ββmaxmax

Range in airRange in air Range is ~ 12 ft / MeVRange is ~ 12 ft / MeV

Bremsstrahlung for high energy beta & high Z Bremsstrahlung for high energy beta & high Z material material Ex. P-32 and LeadEx. P-32 and Lead

Gamma (Gamma (γγ))

PhotoelectricPhotoelectric Compton ScatteringCompton Scattering Pair ProductionPair Production

PhotonPhoton X-rayX-ray Gamma rayGamma ray

Neutrons (n)Neutrons (n)

Often expressed in n / cmOften expressed in n / cm22sec (flux)sec (flux) Thermal neutrons = 0.025 eVThermal neutrons = 0.025 eV Slow neutrons = 1 eV – 10 eVSlow neutrons = 1 eV – 10 eV Fast neutrons = 1 MeV – 20 MeVFast neutrons = 1 MeV – 20 MeV Relativistic neutrons = > 20 MeVRelativistic neutrons = > 20 MeV

U-238 & U-235U-238 & U-235

Shielding ExamplesShielding Examples

Shielding for Multiple Types of Shielding for Multiple Types of RadiationRadiation High Energy BetasHigh Energy Betas BremstrahlungBremstrahlung NeutronsNeutrons GammasGammas

UnitsUnits

Activity: Curie (Ci) 3.7 x 10Activity: Curie (Ci) 3.7 x 101010 disintegrations per disintegrations per secondsecond SI: Becquerel 1 dpsSI: Becquerel 1 dps

Exposure: RoentgenExposure: Roentgen SI: C/kgSI: C/kg

Absorbed Dose: Rad (Roentgen Absorbed Dose)Absorbed Dose: Rad (Roentgen Absorbed Dose) SI: Gray, 1Gy = 100 RadSI: Gray, 1Gy = 100 Rad

Risk: Rem (Roentgen Equivalent Man), Rad x QFRisk: Rem (Roentgen Equivalent Man), Rad x QF SI: Sievert, 1 Sv = 100 RemSI: Sievert, 1 Sv = 100 Rem

Quality FactorsQuality Factors

Type of Radiation QX-rays and Gamma-rays 1Beta particles 1Neutrons of unknown energy 10High-energy protons 10Alpha particles 20

Half-life - the amount of time required for 1/2 of the original sample to decay

The half-life is constant for each radionuclide and varies due to the nuclear structure.

Half-lifeHalf-life

Radioactive DecayRadioactive Decay

Is the process by which the amount of Is the process by which the amount of activity of a radionuclide diminishes activity of a radionuclide diminishes with time.with time.

Examples:Examples:

Radioactive Decay FormulaRadioactive Decay Formula

VariablesVariables A A Activity at time t Activity at time t AA00 Original Activity Original Activity

t t Time Time Decay ConstantDecay ConstantTT1/21/2 Half Life Half Life

ConstantsConstantsln 2 ln 2 0.6930.693 ee11 2.718 2.718

ConceptsConcepts

Radioactive Decay: A = ARadioactive Decay: A = Aooee--λλt t

A =A = λλNN λλ = 0.693 / T = 0.693 / T1/21/2

Inverse Square LawInverse Square Law

Shielding I = IShielding I = IooBeBe--t t

22

21

12

d

dII

Annual US Average Dose from Background Radiation was

Total US average dose equivalent = 360 mrem/year

Total exposure Man-made sources

Radon

Internal 11%

Cosmic 8% Terrestrial 6%

Man-Made 18%

55.0%

Medical X-Rays

NuclearMedicine 4%

ConsumerProducts 3%

Other 1%

11%

Annual US Average Dose from Annual US Average Dose from Background Radiation Now is 625 Background Radiation Now is 625 mremmrem

National Average Dose is US is 625 mrem, with medical being the largest type of increase.

Ionization of Gas – Radiation Ionization of Gas – Radiation DetectorDetector A = recombinationA = recombination B = ionizationB = ionization C = proportionalC = proportional D = limited D = limited

proportionalproportional E = Geiger MullerE = Geiger Muller F = continuous F = continuous

dischargedischarge

MonitoringMonitoring

InstrumentationInstrumentation Gas filledGas filled Solid scintillatorSolid scintillator Liquid scintillationLiquid scintillation

MonitoringMonitoring

DosimetersDosimeters Film badges: beta, gamma, x-rayFilm badges: beta, gamma, x-ray

Permanent recordPermanent record Subject to fadingSubject to fading

Thermoluminescent dosimeter (TLD): beta, Thermoluminescent dosimeter (TLD): beta, gamma, x-raygamma, x-ray No permanent recordNo permanent record Can be used for long term useCan be used for long term use

Pocket ion chamber: gamma, x-rayPocket ion chamber: gamma, x-ray Immediate readoutImmediate readout Shock sensitiveShock sensitive

Biological EffectsBiological Effects

Radiation Effects on Cells: Radiation Effects on Cells: Somatic (early, delayed) & Somatic (early, delayed) & Genetic Dose ResponsesGenetic Dose Responses

Linear, Linear Quadratic, ThresholdLinear, Linear Quadratic, Threshold

Stochastic and Stochastic and Non-stochastic EffectsNon-stochastic Effects

Stochastic effectsStochastic effects Dose increases the probability of the effectDose increases the probability of the effect No thresholdNo threshold Any exposure has some chance of causing the effectAny exposure has some chance of causing the effect Cancer Cancer

Non-stochastic effectsNon-stochastic effects Dose increases the severity of the effectDose increases the severity of the effect ThresholdThreshold Effects result from collective injury of many cellsEffects result from collective injury of many cells Reddening, cataract, skin burnReddening, cataract, skin burn

Biological EffectsBiological Effects

Assumptions Used for Basis of Radiation Assumptions Used for Basis of Radiation Protection StandardsProtection Standards No Threshold Dose, Risk with Given Dose No Threshold Dose, Risk with Given Dose

Increases With Increasing Dose Received, Acute Increases With Increasing Dose Received, Acute vs. Chronic Exposures Not Considered, i.e. vs. Chronic Exposures Not Considered, i.e. RepairRepair

Biological EffectsBiological Effects

Prenatal ExposuresPrenatal Exposures Law of Bergonie & Tribondeau (1906):Law of Bergonie & Tribondeau (1906):

Cells Tend to be Radiosensitive if They Have Three Cells Tend to be Radiosensitive if They Have Three Properties:Properties:

A) Have a High Division RateA) Have a High Division Rate B) Have a Long Dividing FutureB) Have a Long Dividing Future C) Are of an Unspecialized TypeC) Are of an Unspecialized Type

Most and Least Radiosensitive Most and Least Radiosensitive CellsCellsLow SensitivityLow Sensitivity Mature red blood cellsMature red blood cells

Muscle cellsMuscle cells

Ganglion cellsGanglion cells

Mature connective tissuesMature connective tissues

High SensitivityHigh Sensitivity Gastric mucosaGastric mucosa

Mucous membranesMucous membranes

Esophageal epitheliumEsophageal epithelium

Urinary bladder epitheliumUrinary bladder epithelium

Very High SensitivityVery High Sensitivity Primitive blood cellsPrimitive blood cells

Intestinal epitheliumIntestinal epithelium

SpermatogoniaSpermatogonia

Ovarian follicular cellsOvarian follicular cells

LymphocytesLymphocytes

Acute Radiation SyndromesAcute Radiation Syndromes Occurs if specific portions of body are exposed Occurs if specific portions of body are exposed Not likely unless major organs involvedNot likely unless major organs involved 3 ARS syndromes:3 ARS syndromes:

Hematopoietic (blood/bone marrow)Hematopoietic (blood/bone marrow) 100-700 rad100-700 rad Treatment: transfusions, antibiotics, bone marrowTreatment: transfusions, antibiotics, bone marrow transplanttransplant

Gastrointestinal (intestinal lining)Gastrointestinal (intestinal lining) 500-2500 rad500-2500 rad Death likely if dose >1000 radDeath likely if dose >1000 rad Treatment: make individual comfortableTreatment: make individual comfortable

Central Nervous System (brain)Central Nervous System (brain) 2000 rad or more2000 rad or more Death likely within daysDeath likely within days Treatment: make individual comfortableTreatment: make individual comfortable

LDLD5050 for Humans for Humans

Dose of radiation that would result in 50% Dose of radiation that would result in 50% mortality of in the exposed population within mortality of in the exposed population within 30 days of exposure with NO medical 30 days of exposure with NO medical treatmenttreatment

LDLD5050 for Humans is 300 to 500 rad for Humans is 300 to 500 rad

Risks of Radiation ExposureRisks of Radiation Exposure

Low level (< 10,000 mrem) radiationLow level (< 10,000 mrem) radiation Only health effect: cancer inductionOnly health effect: cancer induction

Average occupational dose to research and Average occupational dose to research and lab medicine personnel: <10 mrem/yrlab medicine personnel: <10 mrem/yr Amount is comparable to:Amount is comparable to:

6 cigarettes/yr6 cigarettes/yr Driving 1,000 milesDriving 1,000 miles Living in a stone or brick home for 2 monthsLiving in a stone or brick home for 2 months

Regulations / GuidelinesRegulations / Guidelines

NRCNRC Agreement StatesAgreement States

NCRPNCRP ICRPICRP

ALARA ProgramALARA Program

Exposure LimitsExposure Limits

Regulations: NRC 10 CFR 20Regulations: NRC 10 CFR 20 Note old:Note old:

Whole body: 1.25 rem/quarterWhole body: 1.25 rem/quarter Skin: 7.5 rem/quarterSkin: 7.5 rem/quarter Extremities 18.75 rem/quarterExtremities 18.75 rem/quarter

New:New: Committed Dose Equivalent (CDE)Committed Dose Equivalent (CDE)

Dose to a particular organ:Dose to a particular organ:ه Internal + External Internal + External ≤≤ 50 rem 50 rem

Exposure LimitsExposure Limits

Committed Effective Dose Equivalent (CEDE)Committed Effective Dose Equivalent (CEDE) Dose to a particular organ or organs with weighting Dose to a particular organ or organs with weighting

factor:factor:ه Internal + External Internal + External ≤≤ 5 rem 5 rem

Deep Dose Equivalent (DDE)Deep Dose Equivalent (DDE) Dose at a depth of Dose at a depth of ≥≥ 1 cm: 1 cm:

ه Internal + External Internal + External ≤≤ 5 rem (Eye 5 rem (Eye ≤≤ 15 rem) 15 rem)

Shallow Dose Equivalent (SDE)Shallow Dose Equivalent (SDE) Dose to skin or extremity:Dose to skin or extremity:

ه External External ≤≤ 50 rem 50 rem

Exposure LimitsExposure Limits

Total Effective Dose Equivalent (TEDE)Total Effective Dose Equivalent (TEDE) Sum of dose from external and internal, including Sum of dose from external and internal, including

weighting:weighting:ه Internal + External Internal + External ≤≤ 5 rem 5 rem

Effective Dose EquivalentEffective Dose Equivalent Dose to organ or organs over one year periodDose to organ or organs over one year period

Total Organ Dose EquivalentTotal Organ Dose Equivalent Dose to organ from both internal and external:Dose to organ from both internal and external:

ه Internal + External Internal + External ≤≤ 50 rem 50 rem Exposure to Fetus (Declared Pregnancy) .5 Exposure to Fetus (Declared Pregnancy) .5

Rem/9 monthsRem/9 months

Other Useful InformationOther Useful Information

6CE rule6CE rule

Efficiency = c/d, usually in percentEfficiency = c/d, usually in percent

Effective half life:Effective half life:

Stay time = dose / dose rateStay time = dose / dose rate

REMEMBER UNITS!REMEMBER UNITS!

br

breff TT

TTT

http://www.icrp.org Internal advisory body for ionizing radiationInternal advisory body for ionizing radiation ICRP Publications (examples)ICRP Publications (examples)

  ICRP 84, Pregnancy and medical radiation   ICRP 85, Interventional radiology   ICRP 86, Accidents in radiotherapy   ICRP 87, CT dose management   ICRP 93, Digital radiology

National Council on Radiation ProtectionNational Council on Radiation Protectionand Measurementsand Measurements

http://www.ncrponline.orgformulate and widely disseminate information, guidance and formulate and widely disseminate information, guidance and recommendations on radiation protection and measurements which recommendations on radiation protection and measurements which represent the consensus of leading scientific thinking represent the consensus of leading scientific thinking

publication of NCRP materials can make an important contribution publication of NCRP materials can make an important contribution to the public interest.to the public interest.

NCRP 148 – Radiation Protection in Veterinary MedicineNCRP 148 – Radiation Protection in Veterinary Medicine

NCRP 138 – Management of Terrorist Events Involving Radioactive Material*NCRP 138 – Management of Terrorist Events Involving Radioactive Material*

NCRP 134 – Operational Radiation Safety TrainingNCRP 134 – Operational Radiation Safety Training

NCRP 120 – Dose Control at Nuclear Power PlantsNCRP 120 – Dose Control at Nuclear Power Plants

NCRP 115 – Risk Estimates for Radiation ProtectionNCRP 115 – Risk Estimates for Radiation Protection

Control Programs for Control Programs for Sources of RadiationSources of Radiation

Sealed SourcesSealed Sources

Radiation-Producing MachinesRadiation-Producing Machines

RadioisotopesRadioisotopes

Radioactive MetalsRadioactive Metals

CriticalityCriticality

PlutoniumPlutonium

Control Programs for Control Programs for Sources of RadiationSources of Radiation

Operational FactorsOperational Factors

Employee Exposure PotentialEmployee Exposure Potential• External HazardsExternal Hazards• Internal HazardsInternal Hazards

RecordsRecords

Common RadionuclidesCommon Radionuclides

Sealed sourcesSealed sources Cs-137, Co-60, Ir-192, Am-241, Kr-85, Sr-90, Cs-137, Co-60, Ir-192, Am-241, Kr-85, Sr-90,

Po-208Po-208 Liquid radioactive material for researchLiquid radioactive material for research

P-32, P-33, S-35, H-3, C-14P-32, P-33, S-35, H-3, C-14

Radiation Practice Radiation Practice ProblemsProblemsIonizing RadiationIonizing Radiation

Radiation Practice ProblemsRadiation Practice Problems

1. Iodine-131 has a radiological half life of 8 1. Iodine-131 has a radiological half life of 8 days. If a source originally contained 25 mCi days. If a source originally contained 25 mCi how much remains after 18 days?how much remains after 18 days?

Radiation Practice ProblemsRadiation Practice Problems

2. Two measurements are taken on an 2. Two measurements are taken on an unknown radiation source. The first was 1.3 unknown radiation source. The first was 1.3 mCi, and the second, taken 15 minutes later, mCi, and the second, taken 15 minutes later, was 0.05 mCi. What is the half life of this was 0.05 mCi. What is the half life of this material?material?

Radiation Practice ProblemsRadiation Practice Problems

3. What is the exposure rate from a 15 Ci 3. What is the exposure rate from a 15 Ci Cs-137 source at a distance of 1 foot? (Cs-Cs-137 source at a distance of 1 foot? (Cs-137 gamma energy 0.662 MeV) How about 137 gamma energy 0.662 MeV) How about 10 feet?10 feet?

Radiation Practice ProblemsRadiation Practice Problems

4. How long can a worker stay 10 feet away 4. How long can a worker stay 10 feet away from a 15 Ci Cs-137 source without from a 15 Ci Cs-137 source without exceeding an administratively established exceeding an administratively established quarterly dose limit of 1250 mrem?quarterly dose limit of 1250 mrem?

Non-ionizing RadiationNon-ionizing Radiation

What is Radiation?What is Radiation?

Radiation is energy transmitted by particles Radiation is energy transmitted by particles or electromagnetic wavesor electromagnetic waves

Radiation can be ionizing or non-ionizingRadiation can be ionizing or non-ionizing

DefinitionDefinition

Non-Ionizing RadiationNon-Ionizing Radiation = Radiation that does not = Radiation that does not cause ionizationcause ionization

Types of non-ionizing radiation include:Types of non-ionizing radiation include:1. Ultraviolet (UV) light1. Ultraviolet (UV) light2. Visible light2. Visible light3. Infrared (IR) light3. Infrared (IR) light4. Microwaves4. Microwaves5. Radiowaves5. Radiowaves

Let’s Review – The AtomLet’s Review – The Atom

In their normal state, atoms are electrically In their normal state, atoms are electrically neutral (no net charge)neutral (no net charge)

# protons = # electrons# protons = # electrons

An atom that has gained or lost electrons is An atom that has gained or lost electrons is called an called an ionion

Positive and negative charges cancel

The Ionization ProcessThe Ionization Process

1.1. An in-coming photon interacts with an An in-coming photon interacts with an orbital electronorbital electron

2.2. The electron is ejected from the atom, and The electron is ejected from the atom, and the atom gains a net positive charge. the atom gains a net positive charge.

Incident photon

Ejected electron

Non-Ionizing RadiationNon-Ionizing Radiation

Non-ionizing radiation is electromagnetic in Non-ionizing radiation is electromagnetic in nature:nature: This means it has characteristics of both waves This means it has characteristics of both waves

and particlesand particles However, non-ionizing radiation behaves primarily However, non-ionizing radiation behaves primarily

as a waveas a wave

Electromagnetic SpectrumElectromagnetic Spectrum

The electromagnetic spectrum covers an entire The electromagnetic spectrum covers an entire range of electromagnetic radiationrange of electromagnetic radiation

Which of these are considered to be non-Which of these are considered to be non-ionizing?ionizing?

Electromagnetic SpectrumElectromagnetic Spectrum

Non-ionizing

Types of Non-Ionizing Types of Non-Ionizing RadiationRadiation

Ultraviolet (UV) lightUltraviolet (UV) light Visible lightVisible light Infrared (IR) lightInfrared (IR) light MicrowavesMicrowaves RadiowavesRadiowaves

Non-Ionizing Radiation Non-Ionizing Radiation TermsTerms TermsTerms

EnergyEnergy FrequencyFrequency WavelengthWavelength

WavelengthWavelength FrequencyFrequency EnergyEnergy

1010-18-18 m m 3x103x102626 Hz Hz 1.24x101.24x101212 eV eV

1010-10-10 m m 3x103x101818 Hz Hz 1.24x101.24x1044 eV eV

1010-6-6 m m 3x103x101414 Hz Hz 1.24 eV1.24 eV

101022 m m 3x103x1066 Hz Hz 1.24x101.24x10-8-8 eV eV

Ultraviolet (UV) LightUltraviolet (UV) Light

Ultraviolet light has a wavelength on the Ultraviolet light has a wavelength on the order of 1-100 nanometers (nm)order of 1-100 nanometers (nm)

This is the shortest wavelength of all non-This is the shortest wavelength of all non-ionizing radiationsionizing radiations

Ultraviolet (UV) LightUltraviolet (UV) Light

Ultraviolet light cannot Ultraviolet light cannot be seen by the human be seen by the human eyeeye

It is divided into 3 It is divided into 3 regions regions UVA (most energetic)UVA (most energetic) UVBUVB UVC (least energetic)UVC (least energetic)

Sources of Ultraviolet LightSources of Ultraviolet Light

UV light is emitted UV light is emitted naturally by the sun naturally by the sun and starsand stars

It is produced artificially It is produced artificially by electric lamps and by electric lamps and light bulbslight bulbs

                            

Is Ultraviolet Light Is Ultraviolet Light Dangerous?Dangerous? All UV light can damage skin and eyesAll UV light can damage skin and eyes Over-exposure can lead to sunburn and Over-exposure can lead to sunburn and

various kinds of cancers, including various kinds of cancers, including melanomasmelanomas

It can also lead to weakening It can also lead to weakening

of the immune systemof the immune system

Is Ultraviolet Light Is Ultraviolet Light Dangerous?Dangerous? UV damage to fibrous UV damage to fibrous

tissue is often described as tissue is often described as “photoaging”“photoaging”

Photoaging makes people Photoaging makes people look older because their look older because their skin looses its tightness and skin looses its tightness and it wrinklesit wrinkles

UV Effects by RegionUV Effects by Region

UV-A (400-300 nm)UV-A (400-300 nm) Pigmentation of skin or suntanPigmentation of skin or suntan

UV-B (320-280 nm)UV-B (320-280 nm) Erythemal regionErythemal region Sunburn of skinSunburn of skin Absorbed by cornea of eye (welder’s flash)Absorbed by cornea of eye (welder’s flash)

UV-C (280-220 nm)UV-C (280-220 nm) Bacterial or germicidal effectBacterial or germicidal effect

Protective MeasuresProtective Measures

Ensure that skin and Ensure that skin and eyes are adequately eyes are adequately protected (sunscreen, protected (sunscreen, sunglasses, clothing)sunglasses, clothing)

Never look directly at a Never look directly at a sourcesource

Operate UV lamps in Operate UV lamps in light-tight conditionslight-tight conditions

Visible LightVisible Light

The wavelength of visible light ranges from The wavelength of visible light ranges from 400-700 nanometers400-700 nanometers

Visible light occupies the smallest segment of Visible light occupies the smallest segment of the electromagnetic spectrumthe electromagnetic spectrum

Visible LightVisible Light

Visible light is Visible light is comprised of various comprised of various colorscolors

The separation of The separation of visible light into its visible light into its different colors is different colors is known as known as dispersiondispersion

Visible LightVisible Light

Each color is characteristic of a different Each color is characteristic of a different wavelengthwavelength

Black vs. WhiteBlack vs. White

Technically speaking, Technically speaking, black and white are not black and white are not colors at allcolors at all

Black is the absence of Black is the absence of colorcolor

White is the White is the combination of all combination of all colorscolors

Visible light health effectsVisible light health effects

Retinal burnsRetinal burns Color visionColor vision Thermal skin burnsThermal skin burns

Infrared (IR) LightInfrared (IR) Light

The wavelength of infrared light ranges The wavelength of infrared light ranges from 1-100 micronsfrom 1-100 microns

When an object is not quite hot enough to When an object is not quite hot enough to radiate visible light, it will emit most of its radiate visible light, it will emit most of its energy in the infraredenergy in the infrared

Sources of Infrared LightSources of Infrared Light

Any object which has a Any object which has a temperature above temperature above absolute zero radiates absolute zero radiates in the infraredin the infrared

Even objects we think Even objects we think of as being very cold, of as being very cold, such as an ice cube, such as an ice cube, emit infrared lightemit infrared light

Sources of Infrared LightSources of Infrared Light

Even humans and Even humans and animals emit infrared animals emit infrared radiationradiation

Visible Light vs. Infrared Visible Light vs. Infrared LightLight Some animals can “see” in the infraredSome animals can “see” in the infrared These images give an idea of how different These images give an idea of how different

the world would look if we had infrared eyesthe world would look if we had infrared eyes

Is Infrared Light Dangerous?Is Infrared Light Dangerous?

Heating of tissues in the body is the principal Heating of tissues in the body is the principal effect of infrared radiationeffect of infrared radiation

Excessive infrared radiation can result in heat Excessive infrared radiation can result in heat stroke and other similar reactions, especially stroke and other similar reactions, especially in elderly or very young individualsin elderly or very young individuals

IR Effects by RegionIR Effects by Region

IR-A (0.75 – 2.5 nm)IR-A (0.75 – 2.5 nm) Penetrates skin to some extentPenetrates skin to some extent Penetrate eyes to retinaPenetrate eyes to retina

IR-B (2.5 – 5 nm)IR-B (2.5 – 5 nm) Almost completely absorbed by upper layers of Almost completely absorbed by upper layers of

skin & eyesskin & eyes IR-C (5-300 nm)IR-C (5-300 nm)

Thermal burns on skin & corneaThermal burns on skin & cornea Cataracts (glass blowers)Cataracts (glass blowers)

Microwave RadiationMicrowave Radiation

The wavelength of microwave radiation The wavelength of microwave radiation ranges from about 10 microns to 1 meterranges from about 10 microns to 1 meter

Microwaves have very low energies and very Microwaves have very low energies and very long wavelengthslong wavelengths

Microwave RadiationMicrowave Radiation

Microwave radiation has Microwave radiation has many uses, including:many uses, including: Cellular phonesCellular phones Highway speed controlHighway speed control Food preparationFood preparation

Limit for Microwave OvensLimit for Microwave Ovens

5 mW/cm5 mW/cm22 at 5 cm from surface at 5 cm from surface http://www.fda.gov/cdrh/radhlth/pdf/mwogdeft.pdf

Is Microwave Radiation Is Microwave Radiation Dangerous?Dangerous? Exposure to very high intensity microwaves Exposure to very high intensity microwaves

can result in heating of tissue and an increase can result in heating of tissue and an increase in body temperature (thermal effects)in body temperature (thermal effects)

At low levels of exposure, the evidence for At low levels of exposure, the evidence for production of harmful effects (non-thermal production of harmful effects (non-thermal effects) is unclear and unproveneffects) is unclear and unproven

Is Microwave Radiation Is Microwave Radiation Dangerous?Dangerous?

Currently, exposure Currently, exposure limits are based on limits are based on preventing only thermal preventing only thermal effectseffects

Further research is Further research is needed in order to learn needed in order to learn more about non-thermal more about non-thermal effectseffects

Radiofrequency (RF) Radiofrequency (RF) RadiationRadiation The wavelength of RF radiation (radiowaves) The wavelength of RF radiation (radiowaves)

is greater than 1 meteris greater than 1 meter

Radiofrequency (RF) Radiofrequency (RF) RadiationRadiation Both microwaves and Both microwaves and

radiowaves are used in radiowaves are used in communicationcommunication

As a result, there is As a result, there is considerable overlap considerable overlap between what is between what is identified as a identified as a radiowave and what is radiowave and what is identified as a identified as a microwavemicrowave

Is RF Radiation Dangerous?Is RF Radiation Dangerous?

As with infrared light and microwave As with infrared light and microwave radiation, the primary health effects of RF radiation, the primary health effects of RF radiation are considered to be thermalradiation are considered to be thermal

RF radiation may penetrate the body and be RF radiation may penetrate the body and be absorbed in deep body organs without the absorbed in deep body organs without the skin effects, which can warn an individual of skin effects, which can warn an individual of dangerdanger

Static Magnetic Field Effects at Levels Below 0.5 Static Magnetic Field Effects at Levels Below 0.5 mTmTand Greater Than 0.5mTand Greater Than 0.5mT

Nuclear Magnetic Resonance Imaging (NMR)

Static Magnetic Fields Static Magnetic Fields IntroductionIntroduction Static Magnetic FieldsStatic Magnetic Fields

Nuclear Magnetic Resonance ImagingNuclear Magnetic Resonance Imaging Increasingly used in Biomedical ResearchIncreasingly used in Biomedical Research

in vivoin vivo analysis analysis effectively displays soft tissue contrasts effectively displays soft tissue contrasts MRI is unobstructed by bone MRI is unobstructed by bone

Safety Concerns with Static Safety Concerns with Static Magnetic FieldsMagnetic Fields Attraction of Loose Attraction of Loose

Ferromagnetic MaterialsFerromagnetic Materials Surgical ImplantsSurgical Implants

torqued, dislodged or rotatedtorqued, dislodged or rotated

Pacemaker InterferencePacemaker Interference

Typically Seen Above 0.5 mT (5 Typically Seen Above 0.5 mT (5 Gauss)Gauss)

SMF Exposure Limits / SMF Exposure Limits / GuidelinesGuidelines

ICNIRPICNIRP 200 mT200 mT

Whole body (averaged for day)Whole body (averaged for day) 5000 mT5000 mT

Limbs/extremities (ceiling)Limbs/extremities (ceiling) 40 mT40 mT

Continuous general public Continuous general public exposure exposure

US FDA CDRHUS FDA CDRH 4000 mT4000 mT

Routine Patient CeilingRoutine Patient Ceiling

ACGIHACGIH 60 mT {2000 T}60 mT {2000 T}

Whole body (8hr-TWA) Whole body (8hr-TWA) {Ceiling}{Ceiling}

600 mT {5000 T}600 mT {5000 T} Limbs (8hr-TWA) Limbs (8hr-TWA)

{Ceiling}{Ceiling} 0.5 mT0.5 mT

Medical electronic Medical electronic devicesdevices

NMR Mapping 0.5 mTNMR Mapping 0.5 mT

Issues with Static Issues with Static Magnetic Fields < 0.5 mT:Magnetic Fields < 0.5 mT: Space constraints impacts all involvedSpace constraints impacts all involved Concerns of stopping attention at levels Concerns of stopping attention at levels

below 0.5 mTbelow 0.5 mT Impacts finite radiation protection programs Impacts finite radiation protection programs

resourcesresources Facility IncompatibilitiesFacility Incompatibilities

SMF Affects Below 0.5 mTSMF Affects Below 0.5 mT_________________________________________________________________________________________________________________________________________________________

Examples of static magnetic field interference with commonly used biomedical research equipment at levels 0.5 mT.

_________________________________________________________________________________________

Magnetic Field Strength (mT) Effect or Limit _________________________________________ __________________________________________

0.5 Implanted devices ceiling 0.15 - 0.5 Distortion in cathode ray tubes 0.3 Analytical balance 0.3 Unshielded video camera 0.15 Monitor interference 0.1 Image intensifier & scintillation camera 0.001 - 0.1 Electron microscope _________________________________________________________________________________________

Note: Earth’s magnetic field is 0.03 to 0.07 mT

SMF Problems Frequently SMF Problems Frequently OccurredOccurred Screen “jitter”Screen “jitter” Other electronic Other electronic

interferenceinterference Perceive Problem = Perceive Problem =

RiskRisk Dynamic SituationDynamic Situation Can lead to other Can lead to other

problemsproblems

SMF RecommendationsSMF Recommendations

Move “General Public” limit farther backMove “General Public” limit farther back Move equipment to lower field levelsMove equipment to lower field levels Solicit worker concernsSolicit worker concerns Map field strengths to near background levelsMap field strengths to near background levels Routine assessments encouragedRoutine assessments encouraged

SMF Recommendations SMF Recommendations (cont.) (cont.) Area postings / brochuresArea postings / brochures Educate workers about anticipated Educate workers about anticipated

interferencesinterferences

SMF ConclusionSMF Conclusion

Be aware of potential equipment effects Be aware of potential equipment effects below 0.5 mTbelow 0.5 mT

Equipment incompatibilities may result in Equipment incompatibilities may result in personnel management difficultiespersonnel management difficulties

A Quick Recap…A Quick Recap…

5 types of non-ionizing 5 types of non-ionizing radiation include:radiation include: Ultraviolet (UV) lightUltraviolet (UV) light Visible lightVisible light Infrared (IR) lightInfrared (IR) light MicrowavesMicrowaves RadiowavesRadiowaves

What is a Laser?What is a Laser?

A device that produces A device that produces lightlight

LASER stands for Light LASER stands for Light Amplification by Amplification by Stimulated Emission of Stimulated Emission of RadiationRadiation

Laser ApplicationsLaser Applications

Consumer ProductsConsumer Products

                                

CD Players

Laser Pointers

                  

Laser Printers

Laser ApplicationsLaser Applications

Medical- eye Medical- eye surgery, therapy for surgery, therapy for Carpel Tunnel Carpel Tunnel SyndromeSyndrome

Industrial- welding, Industrial- welding, cuttingcutting

                                

Light BasicsLight Basics

Light travels in waves.Light travels in waves. The electromagnetic spectrum is divided The electromagnetic spectrum is divided

into sections based on wavelength.into sections based on wavelength.

What makes laser light What makes laser light different than conventional different than conventional light?light?Laser light has several unique qualities:Laser light has several unique qualities:

1.1. MonochromaticMonochromatic

2.2. DirectionalDirectional

3.3. CoherentCoherent

But what do these mean?But what do these mean?

Monochromatic LightMonochromatic Light

MonochromaticMonochromatic light is light is light consisting of one light consisting of one wavelength only.wavelength only.

Monochromatic

Polychromatic

Directional LightDirectional Light

DirectionalDirectional light has light has very low divergence.very low divergence.

Conventional light Conventional light spreads in all spreads in all directions, but laser directions, but laser light remains focused.light remains focused.

Directional

Non-Directional

Coherent LightCoherent Light

Coherent lightCoherent light consists consists of waves that are in of waves that are in phase with each other.phase with each other.

Lasing MaterialLasing Material

Lasers contain a medium which is used to Lasers contain a medium which is used to cause the monochromatic effect. There are cause the monochromatic effect. There are several states of lasing mediumseveral states of lasing medium Solid State- Crystal injected “dopant”Solid State- Crystal injected “dopant” Semiconductor- Diode laserSemiconductor- Diode laser Liquid- dye laserLiquid- dye laser Gas- C02 laserGas- C02 laser

Laser ConstructionLaser Construction

Lasing Medium Lasing Medium (gas, liquid, solid, semiconductor)(gas, liquid, solid, semiconductor)

Excitation Mechanism Excitation Mechanism (power supply, flash lamp,(power supply, flash lamp, laser)laser)

Feedback Mechanism Feedback Mechanism (mirrors)(mirrors)

Output coupler Output coupler (semi-transparent mirror)(semi-transparent mirror)

Laser Construction Laser Construction (con’t)(con’t)

Laser UseLaser Use ResearchResearch

• Study of mechanisms at interfacesStudy of mechanisms at interfaces• Detection of single moleculesDetection of single molecules

Medical/DentalMedical/Dental• Eye surgeryEye surgery

Laser Use Laser Use (con’t)(con’t)

CommercialCommercial• Supermarket checkout scannersSupermarket checkout scanners

• Determining site boundaries for constructionDetermining site boundaries for construction

IndustrialIndustrial• CuttingCutting

• WeldingWelding

Laser Hazard ClassificationLaser Hazard ClassificationANSI Z136.1-2000 StandardANSI Z136.1-2000 Standard

Class 1 (Exempt)Class 1 (Exempt)• Incapable of producing Incapable of producing

damaging radiation levelsdamaging radiation levels Class 2 (Low power) Class 2 (Low power)

• Eye protection is an Eye protection is an aversion responseaversion response

• Visible (400-700nm)Visible (400-700nm)• CW upper limit is 1mWCW upper limit is 1mW

Laser Hazard ClassificationLaser Hazard ClassificationANSI Z136.1-2000 Standard (con’t)ANSI Z136.1-2000 Standard (con’t)

Class 3 (Medium Power)Class 3 (Medium Power)• Divided into subclasses, 3a and 3bDivided into subclasses, 3a and 3b• Hazardous under direct or specular reflectionHazardous under direct or specular reflection• Non-hazardous under diffuse reflectionNon-hazardous under diffuse reflection• Normally non fire hazardNormally non fire hazard• CW upper limit 0.5 WCW upper limit 0.5 W

Laser Hazard ClassificationLaser Hazard ClassificationANSI Z136.1-2000 Standard (con’t)ANSI Z136.1-2000 Standard (con’t)

Class 4 (High Power)Class 4 (High Power)• Hazardous to eye and skin from direct Hazardous to eye and skin from direct

viewing/contact, specular, and diffuse viewing/contact, specular, and diffuse reflectionsreflections

• Produce non-beam hazardous such as air Produce non-beam hazardous such as air contaminantscontaminants

• Fire hazard Fire hazard

Bio-EffectsBio-Effects

Primary sites of damagePrimary sites of damage eyeseyes skinskin

Laser beam damage can beLaser beam damage can be thermal (heat)thermal (heat) acousticacoustic photochemicalphotochemical

Eye Bio-EffectsEye Bio-Effects

Three different ways for eye exposureThree different ways for eye exposure Retina (visible and Retina (visible and

IR-A)IR-A) Cornea (UV-B, Cornea (UV-B,

UV-C, IR-C)UV-C, IR-C) Lens (UV-A)Lens (UV-A)

Eye Bio-Effects Eye Bio-Effects (con’t)(con’t)

•Visible (400-700 nm)•Possible damage to Retina

Eye Bio-Effects Eye Bio-Effects (con’t)(con’t)

•Near-ultraviolet (100-330 nm)•Possible damage to Cornea

Eye Bio-Effects Eye Bio-Effects (con’t)(con’t)

•IR (760-3000 nm)•Possible damage to Lens

Skin Bio-EffectsSkin Bio-Effects

Skin SensitivitySkin Sensitivity• Dermis (IR-A)Dermis (IR-A)• Epidermis (UV-B, UV-Epidermis (UV-B, UV-

C)C)

How Often Do Accidents How Often Do Accidents Occur?Occur?

Causative Agent for Accidental Exposure

28%

6% 16%

50%

ExposuredurringalignmentImproper eyewear

Available eyeprotection notusedother

General Laser SafetyGeneral Laser Safety

Wear appropriate protective eyewearWear appropriate protective eyewear Use minimum power/energy required for projectUse minimum power/energy required for project Reduce laser output with shutters/attenuators, if possibleReduce laser output with shutters/attenuators, if possible Terminate laser beam with beam trapTerminate laser beam with beam trap Use diffuse reflective screens, remote viewing systems, etc., Use diffuse reflective screens, remote viewing systems, etc.,

during alignments, if possibleduring alignments, if possible Remove unnecessary objects from vicinity of laserRemove unnecessary objects from vicinity of laser Keep beam path away from eye level (sitting or standing)Keep beam path away from eye level (sitting or standing)

Non-Beam HazardsNon-Beam Hazards

ChemicalChemical Chemical used in dye lasers can be known carcinogens Chemical used in dye lasers can be known carcinogens

or toxic also maybe difficult to disposeor toxic also maybe difficult to dispose OpticalOptical

Plasma radiation can be produced. Similar to welders Plasma radiation can be produced. Similar to welders flashflash

FireFire Class 3b and 4 lasers with high power outputs can Class 3b and 4 lasers with high power outputs can

cause firescause fires ElectricalElectrical

Most common, very high incident in maintenance Most common, very high incident in maintenance

Engineering Control Engineering Control MeasuresMeasures Beam housingsBeam housings

Activation Warning SystemActivation Warning System

ShuttersShutters

Beam Stop or AttenuatorBeam Stop or Attenuator

Remote firing controlsRemote firing controls

InterlocksInterlocks

Administrative Control Administrative Control MeasuresMeasures

Warning signs/labelsWarning signs/labels

SOPsSOPs

TrainingTraining Optical Paths CoveredOptical Paths Covered

Class 2 and 3a Lasers

Class 3b and 4 Lasers

Warning Logo Information Label

PPE Control MeasuresPPE Control Measures

GlovesGloves Be wary of neck ties.Be wary of neck ties. Special clothingSpecial clothing

Eyewear must be for the appropriate laser wavelength, attenuate the beam to

safe levels.

Emergency Procedure Emergency Procedure Shut down the laser systemShut down the laser system

Provide for the safety of the personnel, I.e. first aid, Provide for the safety of the personnel, I.e. first aid,

CPR, etc.CPR, etc.

If necessary, contact the fire department If necessary, contact the fire department

Inform the Radiation Safety DivisionInform the Radiation Safety Division Inform the Principal InvestigatorInform the Principal Investigator

DO NOT RESUME USE OF THE LASER SYSTEM WITHOUT APPROVAL DO NOT RESUME USE OF THE LASER SYSTEM WITHOUT APPROVAL

OF THE LASER SAFETY OFFFICEROF THE LASER SAFETY OFFFICER

IrradianceIrradiance

E = Irradiance = W/cm2E = Irradiance = W/cm2 ФФ = total radiation power W = total radiation power W A = areaA = area a = beam diametera = beam diameter r = viewing distancer = viewing distance ΘΘ = beam divergence = beam divergence

2

27.1

ra

AE

Beam diameterBeam diameter

D = a + r D = a + r ΘΘ

a = beam diametera = beam diameter r = viewing distancer = viewing distance ΘΘ = beam divergence = beam divergence

Optical DensityOptical Density

Log (incident power / transmitted power)Log (incident power / transmitted power)

OD = log (total H / TLV)OD = log (total H / TLV)