University of Notre Dame Department of Risk Management and Safety.

University of Notre Dame

Department of Risk Management and Safety

Machine ProducedRadiation Safety

Training

University of Notre DameRisk Management and Safety

Radiation Safety

• Overview– Ionizing Radiation

• Sources• Effects• Dosage

– Risks of Exposure– Minimizing Risk– Safety in Radiation Producing Machine Use

Ionizing Radiation

• Radiation– Energy in the form of a Particle or Electromagnetic

Wave – Emitted from atoms or via effects applied to charged

particles

• Ionizing Radiation– Radiation with sufficient Energy to eject an electron

from an atom

Ionizing Radiation - Sources• Sources

– Extraterrestrial• Cosmic Radiation• Solar Radiation

– Terrestrial• Atomic Decay• Radiation Producing Machines• Particle Accelerators• Nuclear Reactors

– Internal• Atomic Decay

• Types of Ionizing Radiation

– Alpha particles• Radioactive decay• He nucleus

– Beta particles• Radioactive decay / particle

accelerators• “free” electron

– Neutrons• Radioactive decay / nuclear

reactors• Particle

– X-rays/Gamma Rays• Radioactive decay• Radiation Producing Machines• Electromagnetic Wave

Ionizing Radiation



particles


from an atom

Radiation Safety




Ionizing Radiation - Effects

• X-ray Radiation– Primary radiation source for diffraction experiments– Penetrates matter– Dose depends on several factors

• “Hardness” of X-rays• Exposure time• Distance

• Effects of Ionizing Radiation– Energy from radiation can eject an electron

• Radical formation• Radicals react strongly with other molecules

– Scission of atomic bonds• Fragmentation of molecules

Ionizing Radiation - Effects• Effects:

– Most of the damage is rapidly repaired

– If repair is faulty, burns (erythema) and mutations can occur

– Erythema most common side-effect

– Mutations include:• Alteration of local DNA• Cancer

– Cell Death

• Exposure– Units are measured in

Röntgen (Roentgen) (R)

– 1 Röntgen is 2.58 x 10-

4 Coulomb (C) of charge yielded by energy given to 1 kg of air.

– Usually measured in milliRöntgen (mR)

– Doses measured in mR/h

Ionizing Radiation - Dosage• Radiation Absorbed

Dose (RAD)– Quantifies amount of

energy released to matter from any radiation source

– 1 RAD = 100 erg/g of matter

– Measured in Gray (Gy)– 1 Gy = 1 J/kg = 100 RAD

• Radiation Equivalent Man (REM)– Quantifies biological impact of

a radiation dose– rem = RAD x weighting factor– Weighting factor accounts for

radiation type• X-rays = 1• Alpha particle = 20

– Measured in Sieverts (Sv) 100 mrem = 1 Sv

Ionizing Radiation - Dosage

• Radiation Limits– Set by the World Health Organization (WHO) via

Nuclear Regulatory Committee (NRC)– 500 mrem/yr– Exposure is chronic

• Sources Contributing to Count – Background ~300

mrem/yr• Radon• Ingested Food• Terrestrial• Cosmic Radiation

– Indirect Medical X-rays• ~50 mrem/yr

– Direct Medical X-rays

Ionizing Radiation

• There is thought to be no lower limit to potential detrimental effects occurring from an exposure

• Small increase in birth defects and cancers due to acute exposure.

• Cancer risk increase is 0.04% per rem of exposure

Radiation Notices

• Radiation Producing Machines are required to display a notification when energized

• Clear notification of an open port/open shutter must be apparent (visual notification)

Exposure Prevention• Length of time

– “Fleeting” exposure?– Prolonged exposure?

• Long period of time allows more radiation to be absorbed, higher risk of deleterious effects

• Minimize amount of time near a potential radiation source

• Shielding– Appropriate for Radiation?– Appropriate for Instrument?

• Distance– Radiation “suffers” from a 1/r2 decay from source– Radiation is absorbed by matter; air is matter– Energy dependant

• Cu radiation more absorbed in air than Mo radiation

Ionizing Radiation - Effects

• X-ray Radiation– Primary radiation source for diffraction experiments– Penetrates matter– Dose depends on several factors

• “Hardness” of X-rays• Exposure time• Distance

• Effects of Ionizing Radiation– Energy from radiation can eject an electron

• Radical formation• Radicals react strongly with other molecules

– Scission of atomic bonds• Fragmentation of molecules






– Cell Death







Ionizing Radiation









– Cell Death







Ionizing Radiation




Radiation Notices• International Standards for Radiological Work• Magenta-on-Yellow or Black-on-Yellow Trefoil• Notices must be apparent and external to the work

area

Radiation Notices

• Radiation Producing Machines are required to display a notification when energized

• Clear notification of an open port/open shutter must be apparent (visual notification)

Exposure Risks

• Radiation Producing Machines (RPM)– RPM X-rays are “soft”

• Nearly all of energy is deposited in matter

• Primary Beam– Acute exposure– High dose (100’s – 1000’s of R/min)– Less likely due to beam-stop

• Secondary Scatter– Lower count rate (~0.2 mR/h)– More likely since is scattered radiation from sample– Extremity rather than whole body– Easily detected with a radiation counter

Exposure Prevention• Length of time

– “Fleeting” exposure?– Prolonged exposure?

• Long period of time allows more radiation to be absorbed, higher risk of deleterious effects

• Minimize amount of time near a potential radiation source

• Shielding– Appropriate for Radiation?– Appropriate for Instrument?

• Distance– Radiation “suffers” from a 1/r2 decay from source– Radiation is absorbed by matter; air is matter– Energy dependant

• Cu radiation more absorbed in air than Mo radiation

Exposure Prevention• Distance Decay

I2 = I1 . (x1/x2)2

– I2 = Dose at x2

– I1 = Dose at x1

– x1 = Distance 1

– x2 = Distance 2

• Sample is measured at 25 mR/h at 0.1 m from source, what is the dose at 0.3 m from the source

• 25 mR/h x (0.1/0.5)2

• 25 mR/h x 0.04 =• 1mR/h

Nota Bene: On Radiation Producing Machines the counter should read no more than 0.2 mR/h

at 5 cm from the sample (back scatter)

Exposure Prevention

• Shielding– Primary prevention/protection– Appropriate Shielding is required

• Radiation sources and appropriate shielding– Alpha particle: Paper– Beta particle: Plastic/thin metal

– X-rays: metal sheeting/leaded glass– Gamma Rays: lead-lined metal sheeting– Neutrons: Concrete

• Do NOT remove radiation shielding– Contact a supervisor or Radiation Safety Officer if you need to

do so

• Do NOT override safety interlocks

Pregnancy – A Right to Declare• A pregnant co-worker has the right to declare

the pregnancy• Declaration must be in writing, dated and signed• If a pregnancy is declared, the dose limit to the

foetus is 500 mrem over the entire pregnancy (<45 mrem/month)

• The declaration may be revoked• If a pregnancy is not declared, no special safety

considerations are implemented

Safety Guidelines• First and foremost: Safety is Common Sense

• All of the commentary leads to:ALARA

As Low As Reasonably AchievableConsider what you are doing Consider what the risks are

Minimize those risksBe Mindful

Pregnancy – A Right to Declare• A pregnant co-worker has the right to declare

the pregnancy• Declaration must be in writing, dated and signed• If a pregnancy is declared, the dose limit to the

foetus is 500 mrem over the entire pregnancy (<45 mrem/month)

• The declaration may be revoked• If a pregnancy is not declared, no special safety

considerations are implemented

Safety Guidelines

• The campus Radiation Safety Manual is available in the Laboratory

• At any time you may utilize the Geiger counter if you are unsure about the radiation safety of an instrument

• If you have a concern you may: contact a supervisor, the Radiation Safety Specialist (Notre Dame: Andy Welding, RM&S, ext. 1-5037), the Nuclear Regulatory Commission (NRC, 1-800-695-7403)(radioactive materials), or the Indiana State Department of Health (ISDH, 1-317233-7564)(machines.) Please contact a supervisor first if possible.

• If there is an accident call 911 or 1-5555 from a campus phone

General Laboratory Safety• The X-ray Facility is considered a Laboratory• Please exercise the same precautions you would in

any Laboratory:– Long pants/dress (below knee length)– Close-toed shoes– No Food in the Facility– No Drink in the Facility– Be mindful of your actions

Machine ProducedRadiation Safety

Training

University of Notre DameRisk Management and Safety

Radiation Safety




Ionizing Radiation



particles


from an atom

Ionizing Radiation - Sources• Sources

– Extraterrestrial• Cosmic Radiation• Solar Radiation

– Terrestrial• Atomic Decay• Radiation Producing Machines• Particle Accelerators• Nuclear Reactors

– Internal• Atomic Decay

• Types of Ionizing Radiation

– Alpha particles• Radioactive decay• He nucleus

– Beta particles• Radioactive decay / particle

accelerators• “free” electron

– Neutrons• Radioactive decay / nuclear

reactors• Particle

– X-rays/Gamma Rays• Radioactive decay• Radiation Producing Machines• Electromagnetic Wave

University of Notre Dame Department of Risk Management and Safety.

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