X-ray Safety Training
Texas A&M Health Science Center
Environmental Health and Safety
Rev. 03-2015
Agenda
• Introduction
– Regulatory structure
– Rad safety program
• What is radiation?
– Types of radiation
– Biological effects of
radiation
– Background radiation
– Radiation detection
• HSC Procedures
– Safety (PPE, storage, etc)
– Survey Procedure
REGULATORY OVERSIGHT
Line of Authorization from the State
• US NRC
– Delegates responsibilities
to TDSHS
• TDSHS
– Issues licenses and ensures
compliance within the
state
• HSC
– Radiation Safety Officer
(RSO) and Radiation
Committee (RSC) oversee
institutional compliance
Line of Authorization at the HSC
• HSC
– Holds a “Registration” for use of X-ray generating
devices our campuses
– RSO and RSC
• Create, review, and approve the institutional radiation
safety manual
• Create review and approve new principal investigators
(PIs) to become radiation generating device permittees
EHS website
http://www.tamhsc.edu/ehs/
HSC X-ray Permit
X-RAY PRODUCTION AND BASICS
X-ray production (X-ray tube)
X-ray production - Bremsstrahlung
• Bremsstrahlung X-rays
• Charged particles radiate
electromagnetic energy
whenever they experience a
change in velocity (either in
speed or direction)
• These x-rays are emitted
when high-speed charged
particles undergo rapid
acceleration
X-ray production – electron ejection
• Incoming electron can impart enough energy to result in an
ejection of the K shell electron
• An Electron will drop into the K shell to balance energy
results in the characteristic x-ray
X-ray production - characteristics
• Electron “holes” can be
filled with either an L-shell
or M-shell electron
• N, O, and higher shell
electrons create
characteristic x-rays that are
lost in the noise
• Al or Be filters are used to
block the x-rays of lower
energy than the
characteristic to “harden”
the beam
X-ray basics – ionizing radiation
•
Ionizing
•
•
•
•
•
Alpha
Beta
Gamma
X-ray
Non-Ionizing
–
–
–
–
–
Microwaves
Sunlight
Infrared waves
Radio waves
Lasers
X-ray basics - shielding
• X-rays will pass through
many materials
• Most often, they
require lead or concrete
as a shield
Radiation Penetration
UNITS & DEFINITIONS
USED IN RADIATION
Units & Definitions - Exposure
Roentgen R the unit of exposure to Ionizing Radiation. The amount of γ or xray radiation required to produce 1.0 electrostatic unit of charge in 1.0 cubic
centimeter of dry air.
Use the abbreviation “R/hr” or “mR/hr” when measuring an x-ray, gamma, or beta
dose.
Units & Definitions – Absorbed Dose
RAD (radiation absorbed dose) is a unit of
measurement used to describe the amount of
energy transferred from a source of ionizing
radiation to any material, including human tissue.
• As a unit of exposure, 1 rad means that each gram of air at 0°
C and 1 atmosphere has absorbed 100 ergs of energy.
• As a unit of dose, 1 rad means that each gram of exposed
tissue has abosorbed 100 ergs of energy.
• Note: The SI unit for absorbed dose is the Gray (Gy). 100 rad =
1 Gy
Units & Definitions – Dose + Risk
Different types of ionizing radiation cause differing degrees of
biological effects even when the same amount of energy is
transferred.
To create a universal measurement, the “rad” is multiplied by
the specific quality factor for a type of ionizing radiation to
determine the dose equivalent.
The rate at which an individual is exposed (i.e. an hour verses a
lifetime) also influences the level of biological harm.
Use a dosimeter to measure a dose equivalent.
Units & Definitions – Quality Factor
•
•
•
Used to relate the absorbed dose of
various kinds of radiation to the
biological damage caused to the
exposed tissue
Necessary because the same
amounts absorbed of different kinds
of radiation cause different degrees
of damage
Converts the absorbed dose to a unit
of dose equivalence to compare
damage caused by any kind of
radiation
Radiation Type
Quality Factor
(QF)
X-rays, Gamma rays, Beta
particles
1
Protons
10
Alpha particles
20
Units & Definitions – Dose Equivalent
Dose Equivalent Rem (Roentgen Equivalent Man) is the dose equivalent
for tissue, and takes into account the varying amount of damage to tissue based
on the energy and radiation type, and accounts for tissue sensitivity or the risk of
malignancy from the radiation induced injury.
The dose equivalent can be determined by applying a tissue weighting factor (risk
factor) to the absorbed dose (rad).
Use the abbreviation “Rem/hr” or “mRem/hr” when measuring an x-ray, gamma, or
beta dose.
Note: The SI unit for dose is the Sievert (Sv). 100 Rem = 1 Sv
BIOLOGICAL EFFECTS OF
IONIZING RADIATION
Excitation and Ionization
Excitation
Ionization
Ionizing Water
Radiation Induced Decomposition of Water within a cell
• H2O can form the following:
–
–
–
–
–
–
–
–
–
H2O+
H2
H+
H0
OHOH0
HO2
H2O2
e-
• Free radicals within the cell can result in indirect effects
Harderian Wasp Eggs
Effects of ionizing radiation (DNA)
• DNA damage can result from radiation
– Single and double strand breaks
– Most often repaired successfully by the cell
Potential Outcomes of Radiation Damage to Parent Cells
Radiosensitivity
Law of Bergonie & Tribondeau (1906)
Determinants of Radiosensitivity
Law states that radiosensitivity varies:
1. Directly with rate of cell division
(more metabolically active = more radiosensitive)
2.
Directly with number of future divisions a cell will undergo
(younger cells are more radiosensitive)
3.
Inversely with the degree of cellular differentiation
(stems cells are the most radiosensitive)
Radiosensitive tissues
Radio-sensitive Cells
Radio-resistant Cells
Reproductive Cells
Bone, Cartilage, Muscle
Blood forming tissues
Liver
Epithelium of skin
Kidney
Epithelium of gastrointestinal tract
Nerve tissue
Biological Effect Parameters:
The radiogenic biological effect depends on:
1.
Radiation Type
2.
Rate of Exposure / Absorption
3.
Area Exposed (Variation in Cell Sensitivity)
4.
Variation in Species and Individual Sensitivity
Biological Effects Sumary
• In summary, radiation may:
–
–
–
–
Interact within the body
Deposit energy in the body
Create ionizations in the body
Cause DNA damage
• All of which may lead to biological damage, but:
– Damage may be repaired
– Damage may be benign
– Damage may be neutralized through apoptosis
RADIATION PROTECTION
ALARA
Philosophy
• Radiation doses are
kept as low as possible
• Stems from Linear-NonThreshold dose model
• ALARA program
required by Federal and
State regulations
Keys to ALARA
•
•
•
•
Time
Distance
Shielding
Housekeeping
Radiation Protection Basics
The INDIVIDUAL working with radiation
generating devices
MUST
assume the RESPONSIBILITY for their own safety
AND
must ensure that their actions do not result in a
hazard to others.
Natural Background – Radon
Natural Background - Cosmic
Natural Background – Terrestrial
Natural Background – Dose Map
Natural Background – Internal
Natural Background – Medical
Natural Background - Consumer
Natural Background - Other
Natural Background – Total
Risk versus Dose models
Radiation Risk in Perspective
Health Physics Society Position Statement (March 1996):
• Radiogenic health effects (primarily cancer) are observed in
humans only at high doses.
• Below this dose, estimation of adverse health effects is
speculative since risk of health effects are either too small to
be observed or are non-existent.
• Epidemiological studies have not demonstrated adverse
health effects in individuals exposed to small doses (less than
10 rem) delivered in a period of many years
Regulatory Limits
Maximum Permissible Dose Limits
Whole Body
Lens of eye
Skin
5 Rem / year
15 Rem / year
50 Rem / year
Minor (under 18 y/o)
0.5 Rem / year
Unborn Child of Worker
0.5 Rem over entire
gestation period of DPW
Members of the General Public
0.1 Rem / year
Dose Limit Comparison
• 100,000 rad -Molecular
destruction
• 1,000 rad – 100% of people die:
CNS syndrome
• 450 rad – LD50 (50% of people
die)
• 50 rem/yr – extremity
regulatory limit
• 15 rem/yr – lens of the eye
regulatory limit
• 10 rem/yr – “whole body”
exposure causes measurable
blood changes when acute
• 5 rem/yr – whole body
regulatory limit for trained
radiation workers
• 4.167 rem/qtr – HSC extremity
administrative dose limit
• 1.25 rem/qtr – HSC lens of the
eye administrative dose limit
• 0.417 rem/qtr – HSC whole
body administrative dose limit
RADIATION DETECTION
Detecting Radiation
• Not detectable by any of our natural five sense
• Requires specialized equipment
• Varying types of equipment for different types of
radiation and the type of measurements desired
• Knowledge of the technology is key to making sure
that you know which detector to choose to which
situation
Gas Filled Detectors
Geiger-Mueller
•
Geiger-Mueller detectors can be used
to survey for a variety of different
radioisotopes. Pancake probe GM
detectors (shown on the bottom
right) are the most efficient type of
GM detectors and should be used
when available.
Gas Ionization Curves
Scintillators
Photomultiplier tube
Sodium Iodide Probe
PROCEDURES
Safety Procedures
1.
2.
3.
External Exposure Protection Methods
Laboratory Procedures
Emergency Response
Radiation Safety
• External exposure sources
– Mitigated by:
•
•
•
•
Time
Distance
Shielding
Housekeeping (efficient processes/procedure design)
Dosimetry
• Primary dosimeter is either
a OSL or TLD badge
• Sensitive to gamma and
hard beta radiations
• Provides RSO with dose
information on a quarterly
basis
• Does not provide
information during a real
time exposure to radiation
Dosimetry - Badge
• Dosimeter badges
should be worn on
either the lapel or waist
– Whichever is closest to
the source of radiation
Dosimetry - Ring
• Your ring badge will come with your name on it. Wear the
badge with the name plate facing the source of radiation
• Be sure to wear the ring badge under your gloves to capture
actual dose to your skin
Safe Practices and Procedures
• Consult HSC eduSafe or
Emergency Flipchart and
Manuals
• If injuries occur, they take
first priority
– Call 911
– Provide first aid
– Monitor individual for
contamination
Detector Use – Device Overview
Detector Use – First Steps
1. Turn
meter
on
2. Battery
check
Detector Use – Device Use Tips
3. Audio on
4. Fast/Slow
response
5. Sensitivity
setting
Incident Reporting
• Report the following to EHS
– Actual OR suspected overexposure incidents
– Leakage test failure (shielding is inadequate)
– Exposure to the general public
– Loss of device
Special Rules (Pregnancy)
– A woman is only pregnant when she submits the paperwork.
– Tighter dose restrictions are applied to protect the baby (no more
than 0.5 rem over the course of the pregnancy – 10CFR20)
– A woman has the right to declare and undeclare at any time.
Declared Pregnancy
Security
– Do not be afraid to challenge ANYONE you do not recognize in your
lab or lab area.
• Unauthorized personnel should not be in your lab. Asking for
identification is appropriate in all circumstances.
– No one other than authorized users should have access to radiation
producing devices.
Summary
• What is radiation?
– Types of radiation
– Biological effects of radiation
– Background radiation
– Radiation detection
• HSC Procedures
– Safety (PPE, storage, etc)
– Survey Procedure
Contact Information
• Radiation Safety Officer
– Erich Fruchtnicht
– fruchtnicht@tamhsc.edu
– 979-436-0551
• Bryan EHS Officer
– Marc Goldsmith
– goldsmith@tamhsc.edu
– 979-436-0559
• Temple EHS Officer
– Cristina Bazan
– bazan@tamhsc.edu
– 254-742-7024
• Houston EHS Officer
– Stephanie Colman
– colman@tamhsc.edu
– 713-677-7953
• Dallas EHS Officer
– Hiram Patterson
– hpatterson@bcd.tamhsc.edu
– 214-828-8301
• Kingsville EHS Officer
– Call the RSO for radiation
questions
Test
•
•
•
•
Go to: http://www.tamhsc.edu/ehs/radiation-safety.html
Click on “X-ray Safety Test”
Take test
Click submit