Ionizing & Non-ionizing
Radiation
ENGR 4410 – INDUSTRIAL HYGIENE INSTRUMENTATION
October 23, 2013
Janet M. Gutiérrez, DrPH, CHP, RRPT
Radiation Safety Program Manager
Environmental Health & Safety
713-500-5844
Janet.R.McCrary@uth.tmc.edu
Speaker Biography

Janet M. Gutierrez is manager of the Radiation
Safety Program at The University of Texas Health
Science Center at Houston. She is a Certified
Health Physicist (CHP) and a Registered Radiation
Protection Technologist (RRPT). In August 2011,
she received a Doctorate in Public Health from the
The University of Texas at Houston School of Public
Health (UT SPH), and in 2005, she received a M.S.
in Environmental Sciences / Industrial Hygiene from
UT SPH as well. In 1998, Janet received a B.S. in
Radiological Health Engineering from Texas A&M
University in College Station, TX.
Speaker Biography

Travis Halphen is a Safety Specialist in the
Radiation Safety Program at The University of
Texas Health Science Center at Houston (UTHSCH). He is currently seeking his MPH in
Environmental Health and Occupational Safety from
University of Texas School of Public Health (UT
SPH) and on May 2006 he received a Bachelors in
Medical Physics from Louisiana State University.
He was Assistant Radiation Safety Officer and Laser
Safety Officer at Kansas State University from 2006
to 2008 before he ended up at his current position at
UTHSC-H
Ionizing vs. Non-ionizing Radiation
 Electromagnetic
Spectrum
Radiation
Ionizing & Non-ionizing Radiation
 Units
 Types
 Decay
 Biological
 Inverse
Square Law
 Shielding, HVL, TVL
 Instruments
 Dosimetry
 Biological Effects
 Regulations
 Practice Problems
Effects
 Regulations/Guides
What is Radiation?
 Radiation
is energy transmitted by particles
or electromagnetic waves
 Radiation can be ionizing or non-ionizing
Basic Concepts
 Radiation:
energy
 Ionizing vs. Non-Ionizing: enough energy to
eject orbital electrons
 Radioactivity: excess nuclear energy
Radioactivity
 Radioactivity
is the natural property of certain
nuclides to spontaneously emit energy, in the
form of ionizing radiation, in an attempt to
become more stable.
Basic Concepts
Radionuclide
 Nuclide
 Isotopes have the same Z and a different A;



Isobars have the same A and a different Z;


14N, 14O; 15N, 15C
Isomers have the same A and the same Z;


10C,11C, 12C, 13C, 14C
99mTc, 99Tc
Isotones have the same N and a different A;

14O,13N,12C,11B,10Be,8Li
Basic Concepts

Types of radiation:





Alpha: particulate,
massive
Beta: particulate,
penetrating
Gamma:
electromagnetic,
penetrating
X-ray: electromagnetic,
penetrating
Neutron: particulate, no
charge
Alpha (α)
 Needs
at least 7.5 MeV energy to penetrate
nominal protective layer of skin (7 mg/cm2)

Most α less than this energy, so can not penetrate
skin
 Range
in air
 Range (cm) = 0.56E
for E< 4 MeV
 Range (cm) = 1.24E-2.62 for E> 4 MeV
Beta (β)
Need at least 70 keV energy for beta to penetrate
nominal protective layer of skin
 βave = 1/3 βmax

Range in air
 Range is ~ 12 ft / MeV


Bremsstrahlung for high energy beta & high Z
material

Ex. P-32 and Lead
Gamma (γ)
 Photoelectric
 Compton
Scattering
 Pair Production
 Photon
 X-ray
 Gamma
ray
Neutrons (n)
expressed in n / cm2sec (flux)
 Thermal neutrons = 0.025 eV
 Slow neutrons = 1 eV – 10 eV
 Fast neutrons = 1 MeV – 20 MeV
 Relativistic neutrons = > 20 MeV
 Often
 U-238
& U-235
Shielding Examples
Shielding for Multiple Types of Radiation
 High
Energy Betas
 Bremstrahlung
 Neutrons
 Gammas
Units

Activity: Curie (Ci) 3.7 x 1010 disintegrations per
second


Exposure: Roentgen


SI: C/kg
Absorbed Dose: Rad (Roentgen Absorbed Dose)


SI: Becquerel 1 dps
SI: Gray, 1Gy = 100 Rad
Risk: Rem (Roentgen Equivalent Man), Rad x QF

SI: Sievert, 1 Sv = 100 Rem
Quality Factors
Half-life
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.
Radioactive Decay
Is the process by which the amount of
activity of a radionuclide diminishes
with time.
Examples:
Radioactive Decay Formula
A
A0 
t 

T1/2
Variables
Activity at time t
Original Activity
Time
Decay Constant
Half Life
Constants
ln 2  0.693
e1  2.718
Concepts

Radioactive Decay: A = Aoe-λt


A = λN
λ = 0.693 / T1/2

Inverse Square Law

Shielding I = IoBe-t
2
1
2
2
d
I 2  I1
d
Annual US Average Dose from
Background Radiation was
Total exposure
Man-made sources
Medical X-Rays
11%
Radon 55.0%
Other 1%
Internal 11%
Cosmic 8%
Man-Made 18%
Terrestrial 6%
Nuclear
Medicine 4%
Consumer
Products 3%
Total US average dose equivalent = 360 mrem/year
Annual US Average Dose from
Background Radiation Now is 625 mrem
National Average Dose is US is 625 mrem,
with medical being the largest type of increase.
Ionization of Gas – Radiation Detector
A
= recombination
 B = ionization
 C = proportional
 D = limited
proportional
 E = Geiger Muller
 F = continuous
discharge
Monitoring
 Instrumentation



Gas filled
Solid scintillator
Liquid scintillation
Monitoring
 Dosimeters

Film badges: beta, gamma, x-ray



Thermoluminescent dosimeter (TLD): beta,
gamma, x-ray



Permanent record
Subject to fading
No permanent record
Can be used for long term use
Pocket ion chamber: gamma, x-ray


Immediate readout
Shock sensitive
Biological Effects
 Radiation


Effects on Cells:
Somatic (early, delayed) &
Genetic Dose Responses

Linear, Linear Quadratic, Threshold
Stochastic and
Non-stochastic Effects

Stochastic effects





Dose increases the probability of the effect
No threshold
Any exposure has some chance of causing the effect
Cancer
Non-stochastic effects




Dose increases the severity of the effect
Threshold
Effects result from collective injury of many cells
Reddening, cataract, skin burn
Biological Effects
 Assumptions
Used for Basis of Radiation
Protection Standards

No Threshold Dose, Risk with Given Dose
Increases With Increasing Dose Received, Acute
vs. Chronic Exposures Not Considered, i.e.
Repair
Biological Effects
 Prenatal

Exposures
Law of Bergonie & Tribondeau (1906):




Cells Tend to be Radiosensitive if They Have Three
Properties:
A) Have a High Division Rate
B) Have a Long Dividing Future
C) Are of an Unspecialized Type
Most and Least Radiosensitive Cells
Low Sensitivity
Mature red blood cells
Muscle cells
Ganglion cells
Mature connective tissues
High Sensitivity
Gastric mucosa
Mucous membranes
Esophageal epithelium
Urinary bladder epithelium
Very High Sensitivity
Primitive blood cells
Intestinal epithelium
Spermatogonia
Ovarian follicular cells
Lymphocytes
Acute Radiation Syndromes



Occurs if specific portions of body are exposed
Not likely unless major organs involved
3 ARS syndromes:
 Hematopoietic (blood/bone marrow)
 100-700 rad
 Treatment: transfusions, antibiotics, bone marrow transplant
 Gastrointestinal (intestinal lining)
 500-2500 rad
 Death likely if dose >1000 rad
 Treatment: make individual comfortable
 Central Nervous System (brain)
 2000 rad or more
 Death likely within days
 Treatment: make individual comfortable
LD50 for Humans
 Dose
of radiation that would result in 50%
mortality of in the exposed population within
30 days of exposure with NO medical
treatment
 LD50
for Humans is 300 to 500 rad
Risks of Radiation Exposure
 Low

level (< 10,000 mrem) radiation
Only health effect: cancer induction
 Average
occupational dose to research and
lab medicine personnel: <10 mrem/yr

Amount is comparable to:



6 cigarettes/yr
Driving 1,000 miles
Living in a stone or brick home for 2 months
Regulations / Guidelines
 NRC

Agreement States
 NCRP
 ICRP
 ALARA
Program
Exposure Limits
 Regulations:
 Note



NRC 10 CFR 20
old:
Whole body: 1.25 rem/quarter
Skin: 7.5 rem/quarter
Extremities 18.75 rem/quarter
 New:

Committed Dose Equivalent (CDE)

Dose to a particular organ:
‫ﻬ‬
Internal + External ≤ 50 rem
Exposure Limits

Committed Effective Dose Equivalent (CEDE)

Dose to a particular organ or organs with weighting
factor:
‫ﻬ‬

Deep Dose Equivalent (DDE)

Dose at a depth of ≥ 1 cm:
‫ﻬ‬

Internal + External ≤ 5 rem
Internal + External ≤ 5 rem (Eye ≤ 15 rem)
Shallow Dose Equivalent (SDE)

Dose to skin or extremity:
‫ﻬ‬
External ≤ 50 rem
Exposure Limits

Total Effective Dose Equivalent (TEDE)

Sum of dose from external and internal, including
weighting:
‫ﻬ‬

Effective Dose Equivalent


Dose to organ or organs over one year period
Total Organ Dose Equivalent

Dose to organ from both internal and external:
‫ﻬ‬

Internal + External ≤ 5 rem
Internal + External ≤ 50 rem
Exposure to Fetus (Declared Pregnancy) .5
Rem/9 months
Other Useful Information

6CE rule

Efficiency = c/d, usually in percent

Effective half life: Teff
Tr  Tb

Tr  Tb

Stay time = dose / dose rate

REMEMBER UNITS!
 http://www.icrp.org
 Internal
advisory body for ionizing radiation
 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 Protection
and Measurements
http://www.ncrponline.org
formulate and widely disseminate information, guidance and
recommendations on radiation protection and measurements which
represent the consensus of leading scientific thinking
publication of NCRP materials can make an important contribution to
the public interest.
NCRP 148 – Radiation Protection in Veterinary Medicine
NCRP 138 – Management of Terrorist Events Involving Radioactive Material*
NCRP 134 – Operational Radiation Safety Training
NCRP 120 – Dose Control at Nuclear Power Plants
NCRP 115 – Risk Estimates for Radiation Protection
Control Programs for Sources of
Radiation
Sealed Sources
Radiation-Producing Machines
Radioisotopes
Radioactive Metals
Criticality
Plutonium
Control Programs for Sources of
Radiation
Operational Factors
Employee Exposure Potential
•
•
External Hazards
Internal Hazards
Records
Common Radionuclides
 Sealed

Cs-137, Co-60, Ir-192, Am-241, Kr-85, Sr-90,
Po-208
 Liquid

sources
radioactive material for research
P-32, P-33, S-35, H-3, C-14
Radiation Practice Problems
Ionizing Radiation
Radiation Practice Problems
 1.
Iodine-131 has a radiological half life of 8
days. If a source originally contained 25 mCi
how much remains after 18 days?
Radiation Practice Problems
 2.
Two measurements are taken on an
unknown radiation source. The first was 1.3
mCi, and the second, taken 15 minutes later,
was 0.05 mCi. What is the half life of this
material?
Radiation Practice Problems
 3.
What is the exposure rate from a 15 Ci
Cs-137 source at a distance of 1 foot? (Cs137 gamma energy 0.662 MeV) How about
10 feet?
Radiation Practice Problems
 4.
How long can a worker stay 10 feet away
from a 15 Ci Cs-137 source without
exceeding an administratively established
quarterly dose limit of 1250 mrem?
Non-ionizing Radiation
What is Radiation?
 Radiation
is energy transmitted by particles
or electromagnetic waves
 Radiation can be ionizing or non-ionizing
Definition

Non-Ionizing Radiation = Radiation that does not
cause ionization

Types of non-ionizing radiation include:
1. Ultraviolet (UV) light
2. Visible light
3. Infrared (IR) light
4. Microwaves
5. Radiowaves
Let’s Review – The Atom
 In
their normal state, atoms are electrically
neutral (no net charge)
# protons = # electrons
Positive and negative
charges cancel
 An
atom that has gained or lost electrons is
called an ion
The Ionization Process
1.
2.
An in-coming photon interacts with an
orbital electron
The electron is ejected from the atom, and
the atom gains a net positive charge.
Incident photon
Ejected electron
Non-Ionizing Radiation
 Non-ionizing
radiation is electromagnetic in
nature:


This means it has characteristics of both waves
and particles
However, non-ionizing radiation behaves primarily
as a wave
Electromagnetic Spectrum

The electromagnetic spectrum covers an entire
range of electromagnetic radiation

Which of these are considered to be nonionizing?
Electromagnetic Spectrum
Non-ionizing
Types of Non-Ionizing Radiation
 Ultraviolet
(UV) light
 Visible light
 Infrared (IR) light
 Microwaves
 Radiowaves
Non-Ionizing Radiation Terms

Terms



Energy
Frequency
Wavelength
Wavelength
Frequency
Energy
10-18 m
3x1026 Hz
1.24x1012 eV
10-10 m
3x1018 Hz
1.24x104 eV
10-6 m
3x1014 Hz
1.24 eV
102 m
3x106 Hz
1.24x10-8 eV
Ultraviolet (UV) Light
 Ultraviolet
light has a wavelength on the
order of 1-100 nanometers (nm)
 This is the shortest wavelength of all nonionizing radiations
Ultraviolet (UV) Light
Ultraviolet light cannot
be seen by the human
eye
 It is divided into 3
regions




UVA (most energetic)
UVB
UVC (least energetic)
Sources of Ultraviolet Light
UV light is emitted
naturally by the sun
and stars
 It is produced artificially
by electric lamps and
light bulbs

Is Ultraviolet Light Dangerous?
 All
UV light can damage skin and eyes
 Over-exposure can lead to sunburn and
various kinds of cancers, including
melanomas
 It can also lead to weakening
of the immune system
Is Ultraviolet Light Dangerous?
UV damage to fibrous tissue
is often described as
“photoaging”
 Photoaging makes people
look older because their
skin looses its tightness and
it wrinkles

UV Effects by Region
 UV-A

Pigmentation of skin or suntan
 UV-B



(320-280 nm)
Erythemal region
Sunburn of skin
Absorbed by cornea of eye (welder’s flash)
 UV-C

(400-300 nm)
(280-220 nm)
Bacterial or germicidal effect
Protective Measures
Ensure that skin and
eyes are adequately
protected (sunscreen,
sunglasses, clothing)
 Never look directly at a
source
 Operate UV lamps in
light-tight conditions

Visible Light
 The
wavelength of visible light ranges from
400-700 nanometers
 Visible light occupies the smallest segment of
the electromagnetic spectrum
Visible Light
Visible light is
comprised of various
colors
 The separation of
visible light into its
different colors is
known as dispersion

Visible Light
 Each
color is characteristic of a different
wavelength
Black vs. White
Technically speaking,
black and white are not
colors at all
 Black is the absence of
color
 White is the
combination of all
colors

Visible light health effects
 Retinal
burns
 Color vision
 Thermal skin burns
Infrared (IR) Light
 The
wavelength of infrared light ranges
from 1-100 microns
 When an object is not quite hot enough to
radiate visible light, it will emit most of its
energy in the infrared
Sources of Infrared Light
Any object which has a
temperature above
absolute zero radiates
in the infrared
 Even objects we think
of as being very cold,
such as an ice cube,
emit infrared light

Sources of Infrared Light

Even humans and
animals emit infrared
radiation
Visible Light vs. Infrared Light
 Some
animals can “see” in the infrared
 These images give an idea of how different
the world would look if we had infrared eyes
Is Infrared Light Dangerous?
 Heating
of tissues in the body is the principal
effect of infrared radiation
 Excessive infrared radiation can result in heat
stroke and other similar reactions, especially
in elderly or very young individuals
IR Effects by Region
 IR-A


Penetrates skin to some extent
Penetrate eyes to retina
 IR-B


(2.5 – 5 nm)
Almost completely absorbed by upper layers of
skin & eyes
 IR-C

(0.75 – 2.5 nm)
(5-300 nm)
Thermal burns on skin & cornea
Cataracts (glass blowers)
Microwave Radiation
 The
wavelength of microwave radiation
ranges from about 10 microns to 1 meter
 Microwaves have very low energies and very
long wavelengths
Microwave Radiation
 Microwave
radiation has
many uses, including:



Cellular phones
Highway speed control
Food preparation
Limit for Microwave Ovens
5

mW/cm2 at 5 cm from surface
http://www.fda.gov/cdrh/radhlth/pdf/mwogdeft.pdf
Is Microwave Radiation Dangerous?
 Exposure
to very high intensity microwaves
can result in heating of tissue and an increase
in body temperature (thermal effects)
 At low levels of exposure, the evidence for
production of harmful effects (non-thermal
effects) is unclear and unproven
Is Microwave Radiation Dangerous?
Currently, exposure
limits are based on
preventing only thermal
effects
 Further research is
needed in order to learn
more about non-thermal
effects

Radiofrequency (RF) Radiation
 The
wavelength of RF radiation (radiowaves)
is greater than 1 meter
Radiofrequency (RF) Radiation
Both microwaves and
radiowaves are used in
communication
 As a result, there is
considerable overlap
between what is
identified as a
radiowave and what is
identified as a
microwave

Is RF Radiation Dangerous?
 As
with infrared light and microwave
radiation, the primary health effects of RF
radiation are considered to be thermal
 RF radiation may penetrate the body and be
absorbed in deep body organs without the
skin effects, which can warn an individual of
danger
Static Magnetic Field Effects at Levels Below 0.5 mT
and Greater Than 0.5mT
Nuclear Magnetic Resonance Imaging
(NMR)
Static Magnetic Fields Introduction
 Static

Magnetic Fields
Nuclear Magnetic Resonance Imaging
 Increasingly



used in Biomedical Research
in vivo analysis
effectively displays soft tissue contrasts
MRI is unobstructed by bone
Safety Concerns with Static Magnetic
Fields
Attraction of Loose
Ferromagnetic Materials
 Surgical Implants


torqued, dislodged or rotated

Pacemaker Interference

Typically Seen Above 0.5 mT (5
Gauss)
SMF Exposure Limits / Guidelines

ICNIRP

200 mT


5000 mT


4000 mT


60 mT {2000 T}


Continuous general public
exposure
US FDA CDRH

ACGIH
Limbs/extremities (ceiling)
40 mT



Whole body (averaged for day)
Routine Patient Ceiling
600 mT {5000 T}


Whole body (8hr-TWA)
{Ceiling}
Limbs (8hr-TWA)
{Ceiling}
0.5 mT

Medical electronic
devices
NMR Mapping 0.5 mT
Issues with Static
Magnetic Fields < 0.5 mT:
 Space
constraints impacts all involved
 Concerns of stopping attention at levels
below 0.5 mT
 Impacts finite radiation protection programs
resources
 Facility Incompatibilities
SMF 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)
_________________________________________
0.5
0.15 - 0.5
0.3
0.3
0.15
0.1
0.001 - 0.1
Effect or Limit
__________________________________________
Implanted devices ceiling
Distortion in cathode ray tubes
Analytical balance
Unshielded video camera
Monitor interference
Image intensifier &
scintillation camera
Electron microscope
_________________________________________________________________________________________
Note: Earth’s magnetic field is 0.03 to 0.07 mT
SMF Problems Frequently Occurred
Screen “jitter”
 Other electronic
interference
 Perceive Problem =
Risk
 Dynamic Situation
 Can lead to other
problems

SMF Recommendations
 Move
“General Public” limit farther back
 Move equipment to lower field levels
 Solicit worker concerns
 Map field strengths to near background levels
 Routine assessments encouraged
SMF Recommendations (cont.)
 Area
postings / brochures
 Educate workers about anticipated
interferences
SMF Conclusion
Be aware of potential equipment effects
below 0.5 mT
 Equipment incompatibilities may result in
personnel management difficulties

A Quick Recap…

5 types of non-ionizing
radiation include:





Ultraviolet (UV) light
Visible light
Infrared (IR) light
Microwaves
Radiowaves
What is a Laser?
A device that produces
light
 LASER stands for Light
Amplification by
Stimulated Emission of
Radiation

Laser Applications
 Consumer
Products
Laser
Pointers
Laser Printers
CD Players
Laser Applications
 Medical-
eye
surgery, therapy for
Carpel Tunnel
Syndrome
 Industrial- welding,
cutting
Light Basics
 Light
travels in waves.
 The electromagnetic spectrum is divided
into sections based on wavelength.
What makes laser light different than
conventional light?
Laser light has several unique qualities:
1. Monochromatic
2. Directional
3. Coherent
But what do these mean?
Monochromatic Light

Monochromatic light is
light consisting of one
wavelength only.
Monochromatic
Polychromatic
Directional Light
Directional light has
very low divergence.
 Conventional light
spreads in all
directions, but laser
light remains focused.

Directional
Non-Directional
Coherent Light

Coherent light consists
of waves that are in
phase with each other.
Lasing Material
 Lasers
contain a medium which is used to
cause the monochromatic effect. There are
several states of lasing medium




Solid State- Crystal injected “dopant”
Semiconductor- Diode laser
Liquid- dye laser
Gas- C02 laser
Laser Construction
 Lasing
Medium (gas, liquid, solid, semiconductor)
 Excitation Mechanism (power supply, flash lamp, laser)
 Feedback Mechanism (mirrors)
 Output coupler (semi-transparent mirror)
Laser Construction (con’t)
Laser Use
 Research
•
•
Study of mechanisms at interfaces
Detection of single molecules
 Medical/Dental
•
Eye surgery
Laser Use (con’t)
 Commercial
•
Supermarket checkout scanners
•
Determining site boundaries for construction
 Industrial
•
Cutting
•
Welding
Laser Hazard Classification
ANSI Z136.1-2000 Standard
 Class
•
Incapable of producing
damaging radiation levels
 Class
•
•
•
1 (Exempt)
2 (Low power)
Eye protection is an
aversion response
Visible (400-700nm)
CW upper limit is 1mW
Laser Hazard Classification
ANSI Z136.1-2000 Standard (con’t)
 Class
•
•
•
•
•
3 (Medium Power)
Divided into subclasses, 3a and 3b
Hazardous under direct or specular reflection
Non-hazardous under diffuse reflection
Normally non fire hazard
CW upper limit 0.5 W
Laser Hazard Classification
ANSI Z136.1-2000 Standard (con’t)
 Class
•
•
•
4 (High Power)
Hazardous to eye and skin from direct
viewing/contact, specular, and diffuse
reflections
Produce non-beam hazardous such as air
contaminants
Fire hazard
Bio-Effects
 Primary
 eyes
 skin
sites of damage
 Laser beam damage
 thermal (heat)
 acoustic
 photochemical
can be
Eye Bio-Effects
 Three



different ways for eye exposure
Retina (visible and
IR-A)
Cornea (UV-B,
UV-C, IR-C)
Lens (UV-A)
Eye Bio-Effects (con’t)
•Visible (400-700 nm)
•Possible damage to Retina
Eye Bio-Effects (con’t)
•Near-ultraviolet (100-330 nm)
•Possible damage to Cornea
Eye Bio-Effects (con’t)
•IR (760-3000 nm)
•Possible damage to Lens
Skin Bio-Effects
 Skin
•
•
Sensitivity
Dermis (IR-A)
Epidermis (UV-B, UVC)
How Often Do Accidents Occur?
Causative Agent for Accidental Exposure
6%
16%
28%
Exposure
durring
alignment
Improper eye
wear
Available eye
protection not
used
other
50%
General Laser Safety







Wear appropriate protective eyewear
Use minimum power/energy required for project
Reduce laser output with shutters/attenuators, if possible
Terminate laser beam with beam trap
Use diffuse reflective screens, remote viewing systems, etc.,
during alignments, if possible
Remove unnecessary objects from vicinity of laser
Keep beam path away from eye level (sitting or standing)
Non-Beam Hazards

Chemical


Optical


Plasma radiation can be produced. Similar to welders
flash
Fire


Chemical used in dye lasers can be known carcinogens
or toxic also maybe difficult to dispose
Class 3b and 4 lasers with high power outputs can
cause fires
Electrical

Most common, very high incident in maintenance
Engineering Control Measures

Beam housings

Activation Warning System

Shutters

Beam Stop or Attenuator

Remote firing controls

Interlocks
Administrative Control Measures
Class 3b and 4 Lasers

Warning signs/labels

SOPs
Training
 Optical Paths Covered

Class 2 and 3a Lasers
Warning Logo
Information Label
PPE Control Measures
Gloves
 Be wary of neck ties.


Special clothing
Eyewear must be for the appropriate
laser wavelength, attenuate the beam to
safe levels.
Emergency Procedure

Shut down the laser system

Provide for the safety of the personnel, I.e. first
aid, CPR, etc.

If necessary, contact the fire department
Inform the Radiation Safety Division
 Inform the Principal Investigator

DO NOT RESUME USE OF THE LASER SYSTEM WITHOUT
APPROVAL OF THE LASER SAFETY OFFFICER
Irradiance
E
= Irradiance = W/cm2
 Ф = total radiation power W
 A = area
 a = beam diameter
E
 r = viewing distance
 Θ = beam divergence
1.27A

2
a  r 
Beam diameter
D
a
=a+rΘ
= beam diameter
 r = viewing distance
 Θ = beam divergence
Optical Density
 Log
(incident power / transmitted power)
 OD
= log (total H / TLV)