Chapter 4: Radiation Protection
Principles of Radiation
Protection
• ALARA
•
As low as reasonably achievable
• Time
• Distance
• Shielding
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Time
If you are next to a patient that emits 20 mrem/hour source for 60 min, what is
your exposure?
What if you are only next to that same patient for 6 min, what is your exposure?
Distance
Inverse Square Law =
exposure from a source is inversely proportional to the square of the distance
I1D12 = I2D22
Shielding
While passing through matter, radiations lose energy in the medium via
attenuation (both absorption and scattering).
X = X0 e – ux
X= intensity, X0 = initial intensity, u = linear attenuation coefficient, x=thickness
HVL = 0.693 / u
(HVL is to half life AS attenuation equation is to the decay equation)
Do’s and Don’ts in Radiation Protection
DO
• Post radiation signs in radiation areas
• Wear lab coats and disposable gloves when working
with radioactive materials
• Handle radioactivity behind the lead shield
• Cover work areas with absorbent paper
• Store and transport radioactive materials in lead
containers
• Dispose of radioactive waste in the appropriate
containers
• Monitor hands and feet before leaving the
radiation work area
• Notify the RSO in case of any major spill or
related to radiation
Dother
O Nemergencies
OT
• Wear a radiation monitoring badge
• Identify all radionuclides and dates of assay on
containers
• Use a syringe shield for ALL injections
• EAT, store food, drink or smoke in the laboratory
• Survey work areas for contamination
• Pipette any radioactive material by mouth
• Wipe test work areas weekly
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Math Problems Assignment from Math
Math Book pages 86 – 96
Book
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Radiation dose versus time, distance and
shielding EVEN problems only
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NRC and agreement states (37 agreement states)
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NRC Guidelines
• Title 10 Code of Federal Regulations
• 19 – Notices to workers
• 20 – Standards for Protection against radiation
• 30 – Rules of general applicability to domestic
licensing of byproduct material
• 35 – Medical use of byproduct material
• 71 – Packaging and Transportation of
Radioactive materials
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State of Florida
• Florida Administrative Code 64E-5
• https://www.floridahealth.gov/environmental-health/radiation-control/radmat/64e-5tab1.html
• Part 1 = General Provisions
• Part II = Licensing of Radioactive Materials
• Part III = Standards for Protection
• Part V = X-rays in the healing arts
• Part VI = Use of Radionuclides in the Healing Arts
• Part IX = Notices, instructions and reports to workers, inspections
• Part XIII = Radiation safety requirements for possession and use of sealed and unsealed
sources of radioactive materials
• Part XV = Transportation of Radioactive Materials
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4.2 NRC Regulations of
Radiation Protection
https://www.floridahealth.gov/environmental-health/radiation-con
State of Florida
https://www.floridahealth.gov/environmental-health/radiation-con
Regulations of radiation detection
are covered in
detail in NRC 10 CFR Part 20: Standards for
Protection against Radiation; 2018 and include
issues of exposure and absorbed dose to
occupational worker, members of the public,
pregnant women and minors. It also sets the
rules for receiving and transferring byproduct
materials and guidance for waste disposal.
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NRC Regulations of Radiation Protection
10 CFR Part 20: Standards for Protection against Radiation
• Controlled area
• Radiation Area
• High Radiation Area
• Very high radiation
area
• Restricted area
• Unrestricted area
• An area the licensee can limit access for any
reason
• Area that an individual could receive from a
source, 5 mrem in 1 hour at 30 cm from source
• Area that an individual could receive from a
source, 100 mrem in 1 hour at 30 cm from
source
• Area that an individual could receive from a
source, 500 rad in 1 hour at 1 meter from source
• Area of limited access for the purpose of
protecting individuals from unnecessary
exposure from radiation
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Caution Signs
• Caution Radioactive Material
• 10 times quantity in Part 20, App C
• Caution Radiation Area
• >5 mrem (.05 mSv) in 1 hour at 30 cm
• Caution High Radiation Area
• >100 mrem (1 MSv)in 1 hour at 30 cm
• Very high radiation area means an area, accessible to individuals, in which
radiation levels from radiation sources external to the body could result in an individual
receiving an absorbed dose in excess of 500 rads (5 grays) in 1 hour at 1 meter from a
radiation source or 1 meter from any surface that the radiation penetrates.
• Caution Airborne Radioactivity Area
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Caution Signs – when do you use
what?
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Exceptions to Posting Caution Signs
• Materials under constant control for over 8 hours
• Radiation exposure from a patient who can be released
• Radiation exposure from a sealed source under 5 mrem/h (.05 mSv/hr)at 30
cm
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Other Posting Requirements
• 10 CFR Parts 19 and 20
• License and related documents
• Operating procedures
• Notices of violation,penalties, etc.
• NRC Form 3, Notice to Employees
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Posting Requirement –
10 CFR part 19.11 NRC Form 3
NOTICE TO EMPLOYEES
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State of Florida
Posting Requirement
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Labeling Requirement
• Each container of licensed material must be labeled!
• Label must include radionuclide, quantity of radioactivity and the date
• Labeling is not required for
• Containers holding less that App C to 10 CFR 20
• Containters holding material in concentrations less than those specified in table 4.3
of App B 10 CFR 20
• Containers attended by an individual who takes the precautions necessary to
prevent the exposure to individuals in excess of the limits established by 10 CFR 20
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ALARA Program
• As Low as Reasonably Achievable
• The licensee shall use procedures and engineering controls to achieve
occupational doses and doses to members of the public that are ALARA, taking
into account the feasibility of technology, the economics of improvements in
technology, benefits to the public health and safety and other considerations.
• According to NUREG-1556, vol 9, Appendix L
• 2 action levels have been recommended
• Action Level 1 = in excess of 10% of the permissible limit of occupational exposure
• Action Level 2 = in excess of 30% of permissible limit of occupational exposure,
• corrective action must be taken
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ALARA Program – complete the following
ALARA ACTION LEVEL 1 LIMITS
ALARA ACTION LEVEL 2 LIMITS
• TEDE
• TEDE
• SDE
• SDE
• DDE
• DDE
• LDE
• LDE
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Receiving and Monitoring of
Radioactive Packages
• Procedure
• Limits for survey data (1 meter and surface, wipe survey)
• Efficiency = cpm / dpm
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Requirement of Monitoring of
Occupational Doses of Radiation Workers
• Monitoring badges are required if
• Adult individuals are likely to receive more than 10% of the NRC occupational dose
limit in 1 year
• Minors are likely to receive greater than 100 mrem in one year
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Requirement of Monitoring of
Occupational Doses of Radiation Workers
• Monitoring badges are required if
• Adult individuals are likely to receive more than 10% of the NRC occupational dose
limit in 1 year
• Minors in one year are likely to receive greater than 100 mrem for DDE, greater
than 150 mrem in LDE or greater than 500 mrem in SDE.
• Declared pregnant women are likely to receive greater than 100 mrem during
gestation.
• Caregivers who perform radiologic procedures that are likely to receive 5mSv / year
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Types of Badges – refer to pp. 50-53
• Film badge
• TLD
• OSL
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Bioassay
Bioassays are required to measure the radiation absorbed
dose from inhalation, ingestion or absorption through the
skin.
Handling unsealed radioiodine is the most likely cause for
individuals needing a bioassay.
Capsules can be considered to contain radioiodine in a
sealed form and bioassay would not be necessary unless
capsule is inadvertently broken (crushed, etc).
NRC states routine bioassay time frames
I-123 = 1 day
I-131 = 1 week
Report to NRC within 24 hours if bioassay is positive
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Verification Card for Radioactive Patient
Following 9/11, the US government has implemented
safeguards to establish the Department of Homeland
Security
Address of licensee
Name of patient
Type of radionuclide
Amount of activity
Date of exam
Phone number
expiration
Examples
F-18 = 1 day
Tc-99m = 3 days
I-131 = 95 days
Radiation detectors have been installed at many
checkpoints to detect the presence of any radioactive
dispersal device
Our patients administered with radioactivity may
trigger these detectors
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Thank You
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