Radiation safety training

1.

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
•Radiation Safety
Training

2.

ion Safety Training Exam
ency Response
nsibilities for Radiation Protection
ion Monitoring
lling Radiation Dose
ion Protection Standards
•Training T
cal Effects and Risks of Exposure to Ionizing Radiation
s of Ionizing Radiation
adiation Theory and Fundamentals

3.

• Basic Radiation Theory
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

4.

Atomic Structure
Nucleus:
Contains Protons (+1 charge)
and Neutrons (no charge)
Nuclear Diameter ~ 10-15 m
Electrons:
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 !

5.

• Ionizing versus Non-Io
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
pairs.
The difference between ionizing and non-ionizing
radiation is energy.

6.

Key ‘Dose’ Terms
Absorbed
The rad (radiation absorbed dose) is the energy deposited per unit mass
by
Dose
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
Dose
Takes into account the biological effectiveness, or quality, of different types of
Equivalent
radiation. Dose Equivalent, measured in rems or Sieverts, is equal to the
absorbed
dose times a quality factor (Q).
Equivalent
Takes into account the different probability of effects that occur with the
same
Dose
absorbed dose delivered by radiations with different weighting factors (W R).
The SI unit of Equivalent dose is the Sievert. 1 Sv = 100 rem
Exposure
that
Air Kerma
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
kilogram (C/kg).
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.

7.

Key ‘Dose’ Terms Cont.
• 1 Sv = 100 rem
Radiation
X-Rays, β-Rays, γ• 1 Gy = 100 rads = 100 cGy
Rays
Protons
• 1 cGy = 1 rad
WR Q
1
1
2- 10
5
Alpha Particles,
20 20
Fragments
Equivalent Dose (HT) Fission
= Absorbed
Dose (DT,R) x
Weighting Factor (WR)
HT = DT,R x WR
Dose Equivalent (H) = Absorbed Dose (D) x Quality
Factor (Q)
H=DxQ

8.

More Key Definitions
Radioactivity:
is
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:
Contamination:
controlled.
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.
Isotopes:
Chemical elements with the same Z number .

9.

Types of Ionizing Radiation and
Penetrating Ability
Alpha Particle
Massive; +2
charge
Beta Particle
Some Mass; +/- 1
charge
Gamma / XRay
No mass; No
charge
Neutron
Massive; No
charge

10.

X-Ray (photon) Interactions with Matter
Photodisintegration
X-Ray disappears => liberates a proton, neutron or alpha particle
Photoelectric Effect
X-Ray disappears => liberates an atomic electron

11.

X-Ray (photon) Interactions with Matter
Compton Scatter
X-Ray survives => liberates an electron while changing course and losing some energy
Pair Production
X-Ray disappears => creates an electron / positron pair

12.

tion Hazards in the Workplace
es of Occupational Radiation Exposure
Manufactured/Industrial Sources
Medical Diagnosis and Treatment
Natural Background
es of Background Radiation Exposure
on Sources of Ionizing Radiation
•Radiation S

13.

14.

15.

Accuray radiation generating machines (RGMs) are capable of
creating intense radiation fields. However, if used safely and
properly in well shielded environments, occupational exposures
will be negligible.
TomoTherap
y
H Series
CyberKnife
M6 Series

16.

e acceptability of Risks
uantifying Risks
on Risks
rea of the Body Irradiated, Cell Sensitivity, Individual
ensitivity
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

17.

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
with dose
(Examples: cataracts; erythema; infertility)
Somatic Effects: biological effects that occur on the
exposed individual

18.

TISSUES
which may affect
ORGANS
which may affect
THE WHOLE BODY
which may affect
Radiation Causes I
CELLS
which may affect
MOLECULES
which may affect
ATOMS

19.

(H+
OH-
H 20 +
H 20 -
H20*
e- H 2 0 2 )
Radiation Causes Ionization and Excitation in Water
Reactive species formation (Indirect Effect)
Water molecule dislocation (Indirect
Effect)
Radiation
DNA strand breaks (Direct Effect)
Direct and Indirect Effects
functioning of all known living organisms)
Biology –
genetic instructions used in the development and
(Deoxyribonucleic acid [DNA] encodes the
DNA is the Target of Concern

20.

Radiation Biology
A Changes With Deleterious Effects
A Changes With No Negative Effects
l Death
ection and Repair
age?
at can Happen after Direct or Indirect DNA

21.

Greater total dose and dose rates generally
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
Respons
Effects increase with area irradiated
• Cell Sensitivity
• Area of Body Irradiated
• Type and Energy of Radiation
• Total Dose Received & Dose Rate

22.

Acute
versus
Chroni
wing effects are associated with acute,
whole
body exposure
radiation exposures: high doses over shor
time periods
Possible Effect
None
Slight Blood Changes
ic radiation exposures: low doses over lon
time periods
Dose
0 – 5 rem (0 – 50 mSv)
5 – 50 rem (50 – 500
mSv)
50 – 200 rem (500 –
2000 mSv)
200 – 450 rem (2 – 4.5
Sv)
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

23.

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.
Radiation R
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

24.

Risks In Perspective
Category
Average Life Lost (days)
Smoking 20 cigarettes per day
Being 15% overweight
Agricultural worker
1600
900
320
Consuming alcohol (US Avg.)
Construction worker
Driving a car
230
227
200
Mining and quarrying workers
Manufacturing worker
Recreational swimming
167
40
40
Radon exposure
Skydiving
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
35
25
15
7
6
0.4

25.

•Radiation Protecti
ction of the General Public (100 mrem; 1 mSv)
ction of the Embryo/Fetus
y Control Levels
ational Limits
al / International Recommendations & Laws
Response Models
miological Studies
rinciples of Radiological Protection

26.

The Principles of Radiation Protection
– No practice shall be adopted
unless its introduction produces a net
positive benefit.
This is a societal
decision.
Justification
– All exposures shall be kept
ALARA, economic and social factors being
taken into account.
Optimization

27.

the study of patterns, causes, and effects of health
and disease conditions in defined populations.
•Epidemiologic
Chernobyl Accident, Weapons Test Fallout, Natural Background
vironment
Radium Dial Painters, Miners (Radon Exposure), Radiologists, Nuclea
Workers
cupational
diotherapy Patients
omic Bomb Survivors
s of Human Population Radiation Epidemiological Data
AR - United Nations Scientific Committee on the Effects of Atomic Radiation
iology –

28.

29.

ure Limits and Guidance Documents
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
NSCEAR
miological studies are performed and presented

30.

31.

•Facility Contr
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
ted
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)

32.

ditional safety precautions are available to declared pregnant
rkers
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
conception.
eveloping embryo/fetus, with rapidly dividing cells, is
itive to many environmental factors including ionizing
tion.
Protection of the Embryo/Fetus

33.

of the G
bers of the public are not allowed unescorted access to test
r bunker areas.
100 mrem/yr (1 mSv/yr)
•Protection
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

34.

ess Controls
s, Labels, and Postings
•Controlling Radi
ALARA Concept (Time, Distance and Shielding)
iation Protection
cies and Procedures

35.

Radiation Protection Policies &
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
Procedure
* Personnel Dosimetry Request Form
* Lost, Damaged, or Exposed Personnel Dosimetry
Form
* Declaration of Pregnancy Form
* Declaration of Worker Status Form
* Engineering and Administrative Controls Checklist
* Request and Authorization for Radiation Exposure
History Form
* Notification of Nuclear Energy Worker Status

36.

The ALARA Concept
ALARA is an acronym for As Low As
Reasonably Achievable.
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
radiation sources.
Shielding – incorporate attenuating barriers between radiation sources and personnel
whenever practical.

37.

Reduce Exposures by Minimizing Time &
Dose Rate
Dose = Dose Rate x Time
500 mrem = 10 mrem/hr x 50 hrs
Or
1000 cGy/min x 10 min =
10,000 cGy !!!

38.

Reduce Exposures by Maximizing
Distance

39.

Inverse Square Law - Example

40.

Reduce Exposures by Using Shielding
Materials
Close the Jaws/MLC, Plug Beam, and
Beam Down Whenever Possible/Practical

41.

Radiation Hazard Communication
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
vary
Caution Signs

42.

Engineering Safety Controls
Note: Actuating an
Emergency
Button/Device, or
opening the main test
cell door/gate, will
terminate or prevent
radiation.
Emergency
Buttons/Devices
Warnin
g
Lights

43.

is prohibited to enter a cell in which a radiation device is in use.
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
next Beam-On.
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

44.

iation Detectors
lity Monitoring
onnel Monitoring
•Radiation Mo

45.

Medical and dental imaging
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
•Personnel
Mo
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

46.

•Facility Mon
Test Cell/Bunker Commissioning
and Routine Leakage Surveys
Continuous Area
Monitoring

47.

De
ntial Problems - recombination, dead time, pile
F & magnetic field interference
efits – rugged, inexpensive, appropriate for
ray environment except primary beam
surements
•Radiation
Filled Detectors –Ionization Chambers
iation Leakage Surveys and Area Monitoring

48.

ALARA and caution is warranted as exposure rates approach or
ed: 10 mR/hr; 100 µSv/hr
ys lead with the detector, maximizing your distance from radiation
es.
•Use of Survey In
the natural background radiation level and fluctuations in
ment response.
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
cannot
be used and must be taken out of service.

49.

• Responsibilities for Rad
ave access to personal dose records
ay informed of all risks and associated controls prior to performing radiation
ork duties
als’ Rights
emonstrate responsibility and accountability through an informed, disciplined
d cautious attitude toward radiation
here to all radiation worker requirements, postings, and controls
als’ Responsibilities
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
ement Responsibilities

50.

•Emergency R
all details of the event chronologically.
y and isolate persons who may have received significant radiation
res.
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.

51.

For more information, visit: http://sha
Procedures, forms, links, contact information,
announcements, and more

52.

Accuray is committed to maintaining a robust
radiation safety program. As a result, even our
“Radiation Workers” are expected to receive less
than 10% of the applicable limits (Accuray ALARA
Policy).
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.

53.

Radiation Safety Exam
Please email all questions and
comments to:
[email protected]