Radiation safety training
uestions and comments to: [email protected]
r higher on the Exam
nderstanding SOP 027444 “Radiation Safety Program”
g completion involves:
e the Knowledge, Skills and Abilities needed to work safely with radiation
y for all Accuray “Radiation Worker” personnel
nsibilities for Radiation Protection
lling Radiation Dose
ion Protection Standards
cal Effects and Risks of Exposure to Ionizing Radiation
s of Ionizing Radiation
adiation Theory and Fundamentals
Radiation is simply energy in the form of particles or waves
Particulate Radiation includes: Alpha, Beta and Neutron
Electromagnetic Radiation (Rays or Waves) includes:
X-rays are the most common type of radiation at Accuray
Contains Protons (+1 charge)
and Neutrons (no charge)
Nuclear Diameter ~ 10-15 m
orbit the nucleus (-1 charge)
Atomic Diameter ~ 10-10 m
More than 99.9% of the atomic mass and
all the positive charge are in the nucleus !
Atomic vs. Nuclear Dimensions !
Ionizing Radiation: Means radiation with sufficient energy to liberate an electron from
an atom or
molecule. Such an event can alter chemical bonds and
produce ions or ion
The difference between ionizing and non-ionizing
radiation is energy.
The rad (radiation absorbed dose) is the energy deposited per unit mass
ionizing radiation in a material. One rad equals 100 ergs per gram.
The SI unit of absorbed dose is the Gray. 1 Gy = 1 Joule/kg = 100 rad
Takes into account the biological effectiveness, or quality, of different types of
radiation. Dose Equivalent, measured in rems or Sieverts, is equal to the
dose times a quality factor (Q).
Takes into account the different probability of effects that occur with the
absorbed dose delivered by radiations with different weighting factors (W R).
The SI unit of Equivalent dose is the Sievert. 1 Sv = 100 rem
The unit of radiation exposure in air is the Roentgen (R). It is defined as
quantity of x-rays causing ionization in air equal to 2.58 x 10 -4 coulombs per
Kinetic Energy Released per unit Mass of a small volume of air when it is
irradiated by an x-ray beam. Kerma is measured in Gy.
• 1 Sv = 100 rem
X-Rays, β-Rays, γ• 1 Gy = 100 rads = 100 cGy
• 1 cGy = 1 rad
Equivalent Dose (HT) Fission
Dose (DT,R) x
Weighting Factor (WR)
HT = DT,R x WR
Dose Equivalent (H) = Absorbed Dose (D) x Quality
The spontaneous decomposition or disintegration of unstable atomic nuclei
termed radioactivity. The energy and particles which are emitted during the
decomposition /decay process are called radiation.
Units of Measure:
Becquerel (1 disintegration per second)
Curie (3.7 x 1010 decays per second)
Simply put, contamination is radioactivity where it is not wanted or
Units of Measure:
Becquerels per liter (Bq/L) - if gas or liquid
Bq/cm2 or µCi/m2 - if on a surface
Atomic Number (Z):
Number of protons in the nucleus.
Mass Number (A):
Number of neutrons and protons in the nucleus.
Chemical elements with the same Z number .
Some Mass; +/- 1
Gamma / XRay
No mass; No
X-Ray disappears => liberates a proton, neutron or alpha particle
X-Ray disappears => liberates an atomic electron
X-Ray survives => liberates an electron while changing course and losing some energy
X-Ray disappears => creates an electron / positron pair
es of Occupational Radiation Exposure
Medical Diagnosis and Treatment
es of Background Radiation Exposure
on Sources of Ionizing Radiation
creating intense radiation fields. However, if used safely and
properly in well shielded environments, occupational exposures
will be negligible.
rea of the Body Irradiated, Cell Sensitivity, Individual
tal Dose, Dose Rate, Radiation Type & Energy
•Biological Effects and Ri
to Ionizing Radi
Affecting Biological Response
on Biology – Mechanisms & Effects
omatic, Stochastic, Deterministic, Heritable
cal Response to Ionizing Radiation – Key Terms
Deterministic Effects: definite threshold;
the severity of effect increases with dose
Heritable Effects: a physical mutation or trait that is
passed on to offspring; these have never been
observed in humans but are believed to be possible.
Radiation Biology –
(Examples: cancer – DNA is the target of concern)
Stochastic Effects: probabilistic in nature; existence of a
threshold not clear; probability of occurrence increases
(Examples: cataracts; erythema; infertility)
Somatic Effects: biological effects that occur on the
which may affect
which may affect
THE WHOLE BODY
which may affect
Radiation Causes I
which may affect
which may affect
H 20 +
H 20 -
e- H 2 0 2 )
Radiation Causes Ionization and Excitation in Water
Reactive species formation (Indirect Effect)
Water molecule dislocation (Indirect
DNA strand breaks (Direct Effect)
Direct and Indirect Effects
functioning of all known living organisms)
genetic instructions used in the development and
(Deoxyribonucleic acid [DNA] encodes the
DNA is the Target of Concern
A Changes With Deleterious Effects
A Changes With No Negative Effects
ection and Repair
at can Happen after Direct or Indirect DNA
equate to more damage
Alpha particles are more damaging than X-Rays
Higher energy = greater effect
Rapidly dividing cells and cells that have a long
dividing future tend to be more sensitive
Each person responds differently
• Individual Sensitivity
Radiation Biology – Factors
Effects increase with area irradiated
• Cell Sensitivity
• Area of Body Irradiated
• Type and Energy of Radiation
• Total Dose Received & Dose Rate
wing effects are associated with acute,
radiation exposures: high doses over shor
Slight Blood Changes
ic radiation exposures: low doses over lon
0 – 5 rem (0 – 50 mSv)
5 – 50 rem (50 – 500
50 – 200 rem (500 –
200 – 450 rem (2 – 4.5
480 – 540 rem (4.8 –
Nausea, Fatigue and Vomiting
Hair Loss, Severe Blood Changes,
Possible Death in 2-6 weeks
[LD 50/60] - Lethal Dose to 50% of
5.5 x 10-4 per rem or 5.5 x 10-2 per Sv
k of developing a fatal cancer from radiation exposure:
00 people all received 1,000 mrem, (1 rem), (10 mSv) of
on exposure, we would expect 5 or 6 to die from radiation
cancer and 2,000 to die from all other cancer sources.
imately 20% of all people will develop a fatal cancer in
etime – aside from radiation exposure.
imately 35 – 45% of all people will develop cancer in
etime – aside from radiation exposure.
ion Exposure Is Assumed to Increase Cancer Risk
Average Life Lost (days)
Smoking 20 cigarettes per day
Being 15% overweight
Consuming alcohol (US Avg.)
Driving a car
Mining and quarrying workers
Radiation worker age 18 - 65 (300 mrem/yr, 3 mSv/yr)
All natural hazards
Riding a bicycle
Living within 10 miles of Nuclear Power Plant
ction of the General Public (100 mrem; 1 mSv)
ction of the Embryo/Fetus
y Control Levels
al / International Recommendations & Laws
rinciples of Radiological Protection
– No practice shall be adopted
unless its introduction produces a net
This is a societal
– All exposures shall be kept
ALARA, economic and social factors being
taken into account.
and disease conditions in defined populations.
Chernobyl Accident, Weapons Test Fallout, Natural Background
Radium Dial Painters, Miners (Radon Exposure), Radiologists, Nuclea
omic Bomb Survivors
s of Human Population Radiation Epidemiological Data
AR - United Nations Scientific Committee on the Effects of Atomic Radiation
ry, State and Local Laws
ational Council on Radiological Protection and Measurements (NCRP)
nternational Commission on Radiological Protection (ICRP)
• National / International Reco
nternational Atomic Energy Agency (IAEA)
al and International agencies make recommendations
orld Health Organization
miological studies are performed and presented
ted Areas – Access is prevented or limited for the purpose of
ting individuals from undue risks from radiation exposure
es inside test cells / bunkers when radiation is being
lled Areas – Access is controlled for radiation protection
es (includes areas adjacent to mega voltage enclosures)
tricted Area – Any area that is not controlled for the purposes of
on safety (offices, break rooms, meeting rooms, nontion, non-test areas)
e declaration must be submitted (in writing) to the RSO
tailed training material and information will be made available
istorical dose assessment and job analysis will be performed
porary changes to job duties will be considered
etal dosimeter will be issued
ration of Pregnancy
mbryo/fetus is most susceptible to developing adverse
h effects if exposed during the time period 8-15 weeks
eveloping embryo/fetus, with rapidly dividing cells, is
itive to many environmental factors including ionizing
Protection of the Embryo/Fetus
bers of the public are not allowed unescorted access to test
r bunker areas.
100 mrem/yr (1 mSv/yr)
trict exposure limit to a member of the public is:
Member of the Public: means an individual who is not a
tion worker, has not received radiation safety training and
is not monitored for occupational exposure
s, Labels, and Postings
ALARA Concept (Time, Distance and Shielding)
cies and Procedures
• The most important policy to remember is … never be
inside a test cell or bunker while the beam is made!
• SOP 027444 is the main Radiation Safety Program
* Personnel Dosimetry Request Form
* Lost, Damaged, or Exposed Personnel Dosimetry
* Declaration of Pregnancy Form
* Declaration of Worker Status Form
* Engineering and Administrative Controls Checklist
* Request and Authorization for Radiation Exposure
* Notification of Nuclear Energy Worker Status
ALARA is an acronym for As Low As
Since it is assumed that any radiation exposure involves some risk, doses shall be
maintained as far below the regulatory limits as is practical. To keep doses ALARA,
the three most commonly used techniques are: time, distance and shielding.
Time – whenever practical, minimize the time spent near sources of radiation and
minimize the output from RGMs.
Distance – to the extent practical, maximize the distance between personnel and
Shielding – incorporate attenuating barriers between radiation sources and personnel
Dose = Dose Rate x Time
500 mrem = 10 mrem/hr x 50 hrs
1000 cGy/min x 10 min =
10,000 cGy !!!
Close the Jaws/MLC, Plug Beam, and
Beam Down Whenever Possible/Practical
Some areas require specific authorization or an escort prior to entry.
Be aware of and adhere to the following Hazard Communication:
symbols, signs and other warnings located within and near restricted
or controlled areas.
Radiation ‘Trefoil’ Symbols
Foreground and background colors may
Note: Actuating an
opening the main test
cell door/gate, will
terminate or prevent
is absolutely forbidden to generate radiation while persons are
thin an Accuray shielded enclosure.
rsonnel who need access to an enclosure must get permission
m the operator prior to entry.
ce the test cell is cleared and the door closed, access must be
ntinually monitored, otherwise the cell must be re-cleared prior to
erators must physically enter the test cell, bunker or shielded
closure to ensure no persons are within the enclosure and it is safe
all respects to generate radiation.
Access Controls - Mandatory
Airport checked luggage scans
Notify radiation safety personnel when a dosimeter is lost, damaged
or accidentally exposed
Promptly exchange at regular intervals (usually every three months)
sunlight or moisture
Prevent the dosimeter from receiving excessive exposure to heat,
Keep away from non-occupational radiation sources such as:
Dosimetry Use Guidelines Include:
etry Use is a Requirement for all Radiation Workers
Test Cell/Bunker Commissioning
and Routine Leakage Surveys
ntial Problems - recombination, dead time, pile
F & magnetic field interference
efits – rugged, inexpensive, appropriate for
ray environment except primary beam
Filled Detectors –Ionization Chambers
iation Leakage Surveys and Area Monitoring
ed: 10 mR/hr; 100 µSv/hr
ys lead with the detector, maximizing your distance from radiation
•Use of Survey In
the natural background radiation level and fluctuations in
r on the instrument and perform a battery check.
re the instrument has been recently calibrated.
y inspect the instrument for physical damage or excessive wear.
Damaged or ‘out of calibration’ instruments
be used and must be taken out of service.
ave access to personal dose records
ay informed of all risks and associated controls prior to performing radiation
emonstrate responsibility and accountability through an informed, disciplined
d cautious attitude toward radiation
here to all radiation worker requirements, postings, and controls
sure regulatory compliance and advise on technical issues
sure protection of persons, the environment and property
on Safety Organization Responsibilities
omote a positive radiation safety culture and ensure adequate resources exist
develop/maintain a robust radiation safety program
all details of the event chronologically.
y and isolate persons who may have received significant radiation
entry to the scene of the accident.
te the immediate area of the incident.
ssistance from experienced radiation safety professionals. Contact
uray RSO and local Radiation Safety Personnel.
active materials are involved, limit the spread of contamination.
e radiation dose to involved persons … the first action during any
ncy is to turn off the machine.
Procedures, forms, links, contact information,
announcements, and more
radiation safety program. As a result, even our
“Radiation Workers” are expected to receive less
than 10% of the applicable limits (Accuray ALARA
Non-Radiation Workers are expected to receive
truly negligible exposures: less than 1% of the
natural background and typically below the limits
of routine detection.
Everyone is encouraged to play an active role
regarding radiation safety - think ALARA.
Please email all questions and