radiation safety oct 10 - wsh cbedoksafetygroup.wsh.sg/attachments/articles/radiation...

Radiation Safety

Radiation – is ENERGY IN TRANSITENERGY IN TRANSIT in the form of high speed particles and electromagnetic waves.

NOTENOTE W t l t ti dW t l t ti d

Introduction

NOTENOTE: We encounter electromagnetic waves every day. : We encounter electromagnetic waves every day. They make up our visible light, radio and television They make up our visible light, radio and television waves, ultra violet (UV), and microwaves with a spectrum waves, ultra violet (UV), and microwaves with a spectrum of energies. These examples of electromagnetic waves do of energies. These examples of electromagnetic waves do not cause ionizations of atoms because they do not carry not cause ionizations of atoms because they do not carry enough energy to separate molecules or remove enough energy to separate molecules or remove electrons from atoms.electrons from atoms.

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Bedok Safety Group Seminar on Industrial Health - 21 October 2010

Radiation Safety - by Kelvin Low

Ionizing radiation – is radiation WITHWITH enough energy so that during an interaction with an atom, it can remove tightly bound electrons from their orbits, causing the atom to become

Introduction

charged or ionized. Example is X-RAY

Non-ionizing radiation – is radiation WITHOUTWITHOUT enough energy to remove tightly bound electrons from their orbits around atoms. Example is LASER

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Electromagnetic Spectrum

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IONIZING NON-IONIZINGDAMAGES chemical bonds Lower energy, CAN’T

DAMAGE bonds

Health Effects

Alpha, Beta, Gamma, X-Ray Microwave, Infrared, Visible, Ultraviolet, Laser

CUMULATIVE effects THRESHOLD effects

damage from low levels damage occurs only

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damage from low levels of exposure that can add-up over time

damage occurs only above a “threshold” levelno cumulative effects below “threshold”

Types of Ionizing RadiationAlpha, Beta and Gamma rays from the decay of radioactive substances matter

Ionizing Radiation

X-ray produced electronically by X-ray machines. X-ray machine emits radiation only when the machine is energised.

Alpha

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Alpha decay is a radioactive process in which a particle with two neutrons and two protons is ejected from the nucleus of a radioactive atom.



BetaA beta is a high speed particle, identical to an electron, that is

Ionizing Radiation

emitted from the nucleus of an atom.

GammaGamma rays are electromagnetic

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waves or photons emitted from the nucleus (center) of an atom.

X – RayX Rays are electromagnetic waves or photons not emitted from the nucleus, but normally emitted by energy changes in l t X d ti OCCURSOCCURS h l t f

Ionizing Radiation

electrons. X-ray production OCCURSOCCURS whenever electrons of high energy STRIKESTRIKE a heavy metal target, like tungsten or copper.

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Penetrating Distances

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Sievert (Sv), rem (rroentgen-eequivalent mman) Old unit is rem where 1 Sv = 100 remSievert (Sv) is a unit of RADIATION DOSERADIATION DOSE due to ionizing

Ionizing Radiation Dose

Sievert (Sv) is a unit of RADIATION DOSERADIATION DOSE due to ionizing radiationExpress doses received by human beingsDose depends on ACTIVITYACTIVITY of radioactive source, distance, shielding and exposure time.

Sievert is named after Rolf M Sievert aSievert is named after Rolf M Sievert a

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Sievert is named after Rolf M. Sievert, a Sievert is named after Rolf M. Sievert, a Swedish Physicist who was one of the Swedish Physicist who was one of the pioneers in protection against ionizing pioneers in protection against ionizing radiationradiation



Ionizing radiation can cause two main biological effects, namely

Somatic effects (acute & chronic) in which the damage

Effects Due To Ionizing Radiation

Somatic effects (acute & chronic) in which the damage appears in the IRRADIATED PERSON HIMSELFIRRADIATED PERSON HIMSELF, and

Genetic effects which arise only in the OFFSPRING OFFSPRING of the irradiated persons as a result of radiation damage to germ cells in the reproductive organs.

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Dose (Sv) Effect1,000 Spastic seizures; death in minutes.

Acute Effects of Irradiation at Different Doses

100 Damage to central nervous system; death in hours.

10 Circulating changes; death in days.

1 Radiation sickness (nausea, vomiting, fatigue; following a short latent period epilation, loss of appetite, fever, diahorrea, rapid emaciation, and

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possible death); decrease in life expectancy and disease resistance; sterility, erythema – reddening of the skin.

0.1 No obvious injury.



Sv Casualties Deaths

Statistics for Chernobyl Accident

< 1 105 0

1 – 4 53 1

4 – 6 23 7

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6 - 16 22 21

Effect Mean Latent Period Evidence For Effect

Leukemia 8 - 10 yearsAtomic bomb casualties,M di l X t t t

Some Chronic Effects of Radiation

yMedical X-ray treatment

Bone cancer 15 years Radium luminous dial painters

Thyroid cancer 15 - 30 yearsAtomic bomb casualties,Medical treatment

Lung cancer 10 - 20 years Mine workers

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Life shortening -- Experiments with mice

Cataract 5 - 10 years Atomic bomb casualties



(a) The dose from any medical or dental exposure as a patient, from the exposure to natural background radiation or from other exposures received by the radiation worker as a member of the public shall not be taken into account.

Application Dose Limit per year (mSv)

Eff ti d ( h l b d ) 201

Second Schedule - Part I Dose Limits For Radiation Workers

(b) Where only a part or parts of the body are irradiated by external radiation, the effective dose received from external radiation shall be determined by calculating the sum WTHTover all organs and tissues irradiated, where ----

Effective dose (whole body)Equivalent dose in

201

the lens of the eyethe skin2

the hands and feet

150

500

500

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g ,(i) HT is the equivalent dose received by any particular tissue or organ T; and(ii) WT is the weighting factor for that tissue or organ

1. The limit on effective dose (whole body) is 20 mSv per year, averaged over defined periods of 5 years and with the further provision that the effective dose shall not exceed 50 mSv in any single year.

2. The limit of 500 mSv for skin is averaged over areas of no more than 1 cm2 regardless of the area exposed

Application Dose Limit per year (mSv)

Effective dose (whole body)Equivalent dose in

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the lens of the eye 15

Second Schedule – Part II Dose Limits For Individual Members Of The Public

the lens of the eyethe skin2

1550

1. In special circumstances, a higher value of effective dose for the whole body is allowed in a single year provided that the average over 5 years does not exceed 1 mSv per year. The limit shall apply to the sum of the relevant doses from the external exposure in the specified period and the committed effective dose

2. The limit of 50 mSv for skin is averaged over areas of no more than 1 cm2 regardless of the area exposed

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Whole body effective dose limit for radiation worker should not be more than 20 mSv a year for whole body exposure and 1 mSv a year for public members

Control of Ionizing Radiation ExposureControl of Ionizing Radiation Exposure

All unjustifiable doses should be avoidedHigh dose accumulation is to be avoided for women of reproductive capacity

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ShieldingShieldingTimeTime

Reduction of Exposure to Ionizing RadiationReduction of Exposure to Ionizing Radiation

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DistanceDistance



Distance - keeping a RESPECTFULRESPECTFUL distance from a radiation source is often the most effective way of REDUCINGREDUCING dose (moving from 1 m to 10 m from strong

di ti d di ti d i d b 100

Reduction of Exposure to Ionizing Radiation

radioactive source reduce radiation dose received by 100 times).

Shielding – INCREASEINCREASE the amount of shielding will DECREASEDECREASE the amount of exposure.

Time - radiation dose is directly proportional to exposure time Keep exposure time to as SHORTSHORT as possible

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time. Keep exposure time to as SHORTSHORT as possible.

Engineering ControlsX-ray machine adequately shielded so that radiation level anywhere outside the enclosure when the X-ray

Control Measures

y ymachine is energized is within legal limit.

Effective safety interlocks shall be provided so that when the X-ray machine has to be switched off before any enclosure door can be opened and cannot be switched on so long as the door is opened.

Ad t i t i th i i it h ll b

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Adequate warning to everyone in the vicinity shall be given by appropriate light or audible signals or both while X-ray machine is energized.



Example of Safe Work ProceduresElectrical Safety

Control Measures

Lockout/Tagout (LOTO)

Reproductive Health Hazard

Radiation Safety

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LicensesApply for required licenses L3 (machine) L5

Operating a X-ray machine

Safe Work Procedures

Apply for required licenses, L3 (machine), L5 (Supervision of R1 holder) and/or R1 (Radiation Worker) from National Environment Agency (NEA)Applicant must be at least 18 years old

Medical Examination

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Before beginning radiation work. Must be certified fit for radiation work by registered medical doctor. If there is directive from NEA.



Site MonitoringA monitoring survey is required after installation of a new X-ray machine,


move a X-ray machine or modify a X-ray machine

Geiger counterScintillation counter

Training

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TrainingAll radiation worker must be adequately trained on operation of X-ray machine and know the hazards associated with the work.

Warning Label


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Safety GuidesFollow the recommended safety guidelines from the equipment manufacturer


q pReport any abnormal situation to immediate supervisor, Radiation Safety Officer and/or Safety Department

Test interlocks at the frequency required for your particular type of X-ray machine

Document and understand alignment procedures for the

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X-ray machine you own or use

Pregnant radiation worker shall declare pregnancy to their immediate supervisor and managers so that arrangement can be made to exempt them from working X-ray machine during the pregnancy.

Personal DosimetersThermoluminescent Dosimeter (TLD) is used to measure the estimated radiation dose absorbed thru


skin and body.

TLD consists of TLD card and holder, also known as TLD badge.

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Personal DosimetersTLD card provide early warning

TLD d i i d bi thl


TLD card is issued bi-monthly

TLD card is tested individually, data is retained forever (by NEA)

After the TLD cards are processed, a dose report is generated

M i S

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Measures exposure in mSv

Identifies radiation energy, type, and direction

TLD Badge – Do’s and Don’ts

DO Put in TLD card properly in TLD holder with name appearing on window


name appearing on windowWearer name should be against the wearer when TLD badge is wornWear TLD at chest level when working around X-ray machineKeep TLD at workplace

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DON’T Place TLD on X-ray machineDeliberately expose TLD to radiationWear TLD during medical testsExpose TLD to heat



Establish System for Reporting When

Acquire a X-ray machine


Dispose a X-ray machine

Suspect an abnormal condition

Move a X-ray machine

Modify a X-ray machine

Return a X ray machine to service

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Return a X-ray machine to service

Radiation Protection ActRadiation Protection (Ionizing Radiation)

Licenses required for manufacture possess use and

Statutory RequirementStatutory Requirement

Licenses required for manufacture, possess, use and import, and sale of radioactive and irradiation apparatusRadiation workers must not be younger than 18 yrs old, required to register, go for medical examination, instructed to do radiation work and wear personal dosimeter

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dosimeter.Not allowed to receive excess of annual dose limit in 2nd Schedule



Radiation Protection (Ionizing Radiation) RegulationsMedical examination include full blood examination & certified fit by approved registered doctor before


y pp gengaged in radiation workRadiation worker has been adequately trainedTransfer record in approved form for employees who had left the companyRadioactive materials, irradiating apparatus and radiation areas must be appropriately labeled

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radiation areas must be appropriately labeledSafe storage and accounting of radiation sourcesDesign aspects such as shielding, interlocks, warning devices, layout, instrumentation, ventilation must meet applicable requirements

Radiation Protection (Ionizing Radiation) RegulationsPenalty for individual not exceeding $2000Appropriate procedures in dealing with radiation


Appropriate procedures in dealing with radiation accidentsCalibration of area monitors and dosimetersL3 - license to keep or possess an irradiating apparatus (company)L5 - license to use irradiating apparatus (individual)

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5 ce se to use ad at g appa atus ( d dua )R1 - license to register as a radiation worker (individual using ionizing irradiating apparatus under supervision of licensee L5)



Types of Non-Ionizing RadiationElectromagnetic radiation & fields with wavelengths greater than 100 nm & acoustic radiation & fields with

Non-Ionizing Radiation

frequencies above 16 KHz,Microwave RadiationInfrared RadiationVisible Radiation Ultraviolet RadiationUlt d

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UltrasoundLaser

LASER is an acronym for LLight

AAmplification by

Laser

LASER light differs from ordinary light in three ways,

SStimulated

EEmission of

RRadiation

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Monochromatic (single wavelength)

Coherent (in-phase)

Directional



Laser can pose more of a hazard than ordinary light because they can focus a lot of energy onto a small area

Laser

LASERS ARE “POINT” SOURCES OF LIGHTLASERS ARE “POINT” SOURCES OF LIGHT

LASER(POINT SOURCE)

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INCANDESCENT LIGHT BULB(EXTENDED SOURCE)

Lasing media (gas, liquid, solid, semiconductor)Excitation mechanism (power supply, flash lamp, laser)Feedback mechanism (mirror grating)

Laser DesignLaser Design

Lasing medium

Feedback mechanism (mirror, grating)Output coupler (partially reflecting mirror)

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Feedback

mechanism

Output

Coupler

Excitation mechanism



Lasers are generally classified according to the materials used

Gas (CO Argon)

Types of LaserTypes of Laser

Gas (CO2, Argon)

Solid (Nd:YAG, Ti:Sa)

Semiconductor (Gallium-Arsenide)

Dye

Mode of Operation – Continuous Wave; P l d W Q it h d

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Pulsed Wave; Q-switched

Wavelength – UV; Visible to Near IR; Mid to Far IR

Beam HazardsEye

Ski

Non Beam HazardsChemical

El t i l

Laser HazardsLaser Hazards

Skin Electrical

Explosion

Fire

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Eye HazardsRisk for retinal injury is dependent on wavelength and/or total power entering the eye


For wavelengths that focus on the retina, the optical gain of the eye is about 100,000 times! If the irradiance entering the eye is 1mW/cm2, then the irradiance at the retina will be 100 W/cm2

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Skin HazardSkin injury from laser energy is primarily THERMAL

( t f UV) Hi hl d d t


(except for UV). Highly dependent on:

Beam Irradiance

Exposure Duration

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Non-beam HazardsChemical Hazards - from dyes; from solvents used to clean optics


solvents used to clean optics

Electrical Hazards – from high voltage power supplies

Explosion Hazards – from high pressure arc lamps, from compressed gases

Fire Hazards – from electrical circuit

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Fire Hazards from electrical circuit, ignition of gases, flammable solvents BOOM

Class Description1 Lasers that are inherently safe & incapable of producing

dangerous levels of emissions

Laser Classification

2 Do not normally present a hazard because of normal human bright-light aversion response. May present potential eye hazard if viewed directly for long time,

3a Would not injure the eye if viewed for only momentary periods with the unaided eye, Eye damage possible if viewed with collection optics

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3b Hazardous under direct viewing or a reflected beam is viewed.

4 Hazardous under all viewing conditions, may produce significant skin hazards as well as fire hazards.



Protective housing that prevents human access during operation to laser

Enclosed beam path

Engineering Controls

Enclosed beam path

Safety Interlocks

Remote control firing

Key –actuated master control

Beam stops and attenuators

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Example of Safe Work ProceduresElectrical Safety

L k t/T t (LOTO)

Control Measures

Lockout/Tagout (LOTO)

Radiation Safety

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LicensesApply for required licenses, N2 (machine) and/or N3 (laser worker) from National Environment Agency

Safe Work ProceduresSafe Work Procedures

Applicant must be at least 18 years old

Medical ExaminationBefore beginning laser work. Must be certified fit for laser work by registered medical doctor.

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TrainingAll radiation worker must be adequately trained on operation of X-ray machine and know the hazards associated with the work.

Protective EyewearAppropriate for all wavelengths in use


Sufficient attenuation (Optical Density) at wavelengths in use

Good visible light transmission

Good field of viewing

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Comfortable to wear



Warning Label


LASER RADIATIONDO NOT STARE INTO BEAM OR VIEW

DIRECTLY WITH OPTICAL INSTRUMENTS

TYPE OF LASERPOWER & WAVELENGTH

CLASS 3A LASER PRODUCT

LASER RADIATIONDO NOT STARE INTO BEAM OR VIEW


CLASS 2 LASER PRODUCT

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Class 3a Laser ProductClass 2 Laser Product

Warning Label


LASER RADIATIONAVOID EXPOSURE TO BEAM


CLASS 3b LASER PRODUCT

LASER RADIATIONAVOID EYE OR SKIN EXPOSURE TO DIRECT OR SCATTERED RADIATION


CLASS 4 LASER PRODUCT

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Class 3b Laser Product Class 4 Laser Product



Do not attempt to operate systems with enclosures openDo not defeat or tamper with safety interlocks

Safety Guides


Do not defeat or tamper with safety interlocksDo not operate machine if enclosures are damagedFollow the recommended laser safety guidelines of the equipment manufacturer as in the user/service manual

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For Repair WorkControl access to the equipment during service e.g. Laser curtains, barriers, closing entranceways


Post NOTICE sign at entranceway into controlled areaAfter maintenance or servicing,

Remove NOTICE signRemove unnecessary objects from the vicinity of the laser

NOTICE

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the laserChecked to confirm all safety interlocks are operating effectively

LASER REPAIR IN PROGRESS

Laser Safety Eyewear Required



Laser should be discharged in a non-reflective & fire resistant backgroundArea should be cleared of personnel for a reasonable


Area should be cleared of personnel for a reasonable distance on all sides of laser beamLooking into the primary laser beam, specular reflections of the beam, including those from lens surface, should be avoided at all timesAvoid aiming laser into eye to prevent looking along the axis of the beam which increases the hazard from

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axis of the beam which increases the hazard from reflections

Laser work should be carried out in areas of high general illuminations to keep pupils constricted thus limiting the energy which might inadvertently enter the eyes


Personnel should be instructed on potential eye hazards & the importance of limiting unnecessary exposureSafety eyewear designed to filter off specific frequencies & to provide protection should be worn at all times.Binoculars or aiming telescopes should not be used to view direct laser beam or reflected beam from mirrors

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unless the beam intensities are greatly below safety levels.



Radiation Protection ActThe Radiation Protection (Non-Ionizing Radiation) Regulations

A l t th f ll i i i i t


Apply to the following non-ionizing apparatus: a) ultraviolet sunlamps (for irradiating living human

body) ; b) microwave ovens ; c) medical and industrial ultrasound apparatus; d) magnetic resonance imaging (MRI) apparatus; e) entertainment lasers; and

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e) entertainment lasers; and f) high power lasers

N2 - license to keep or possess for use of class 3b & 4 lasers & ultrasoundN3 - license to use class 3b & 4 lasers

The Radiation Protection (Non-Ionizing Radiation) Regulations

Detail requirements in dealing with NIR


Detail requirements in dealing with NIR

Requirements on shielding, interlocks, warning devices

Appropriately labeled to give adequate warning

Worker must be at least 18 yrs old to perform laser radiation work, adequately trained & holds a license

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radiation work, adequately trained & holds a license for class 3b or 4 lasers



Thank You



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