radiation safety program overview and terminology robert forrest, chp radiation safety officer...
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Radiation Safety Program Radiation Safety Program Overview and TerminologyOverview and Terminology
Robert Forrest, CHP
Radiation Safety OfficerEnvironmental Health and Radiation Safety
RememberRemember
Don’t be the RSO!
Who gets the blame?Who gets the blame?
“The licensee, through its Radiation Safety Officer, failed to ensure that radiation safety activities were being performed in accordance with the
established procedures.”
Radiation SymbolRadiation Symbol
New ISO Radiation SymbolNew ISO Radiation Symbol
Public PerceptionsPublic Perceptions
Nuclear Weapons
Cancer
Invisible, industrial hazard
Recommending Groups Recommending Groups
ICRP - International Commission on Radiological Protection
NCRP - National Council on Radiological Protection
ICRU - International Commission on Radiological Units
BEIR - Biological Effects of Ionizing Radiation Committee
Regulatory AgenciesRegulatory Agencies
NRC
DOE
DOT
EPA
FDA
OSHA
Naval Reactors
US Post Office
States
Local Municipalities
Main Regulatory AuthoritiesMain Regulatory Authorities
NRC regulates:
Byproduct material
Reactors and Fuel
State regulates:
Accelerator material
Energized Equipment
Agreement States vs. NRCAgreement States vs. NRC
State accepts NRC rules
State can be more restrictive
NRC retains control of Reactors and Fuel
Radiation Safety ProgramRadiation Safety Program
Commensurate with scope of activities
Governed by:
Regulations
License Conditions
Local Policies and Procedures
NRC LicensesNRC Licenses
License authorizes who, what, where and how
Requirements above and beyond regulations
Includes all correspondence back and forth between licensee and regulatory agency
NRC LicensesNRC Licenses
Specific License
Names authorized users
Requires amendments to change small items
Broad Scope License
Licensee can designate authorized users
Licensee can modify “ministerial” items
Organizational Organizational ResponsibilitiesResponsibilities
Executive Management
Radiation SafetyCommittee
Radiation Safety Officer
TerminologyTerminology
Radioactive Material
Radiation
Contamination
Half-life
Activity
Radioactive MaterialRadioactive Material(unstable material which spontaneously transforms (unstable material which spontaneously transforms
usually emitting some type of radiation)usually emitting some type of radiation)
RadiationRadiation(particulate or electromagnetic energy emitted during (particulate or electromagnetic energy emitted during
radioactive decay)radioactive decay)
ContaminationContamination(radioactive material spread into an unwanted place)(radioactive material spread into an unwanted place)
Half-LifeHalf-Life
The time required for any given radioisotope to decrease to one half of its original activity.
T1/2 = ln 2 /
The radiological half-lives for Tc-99m and
I-131 are 6 hours and 8 days, respectively.
Half lifeHalf life
Tc-99m Decay
0
500
1000
0 10 20 30 40
Hours
Ato
ms
Half lifeHalf life
Tc-99m Decayλ = 0.116 hr-1
1
100
10000
0 12 24 36 48 60
Hours
Ato
ms
ActivityActivity the rate of decay * the number of atomsthe rate of decay * the number of atoms
A = A = *N*N
Current Unit
Curie (Ci)
1Ci = 3.7 E 10 Bq
SI Unit
Becquerel (Bq)
1 Bq = 1 d/s
1 Bq = 2.7 E -11 Ci
ActivityActivity
A = *N
If N = 1x109 atoms
Tc-99m, A = (0.116 hr-1)(1x109 atoms)
A = 3.22 x 104 Bq (0.87 μCi)
I-131, A = (3.61x10-3 hr-1)(1x109 atoms) A = 1 x 103 Bq (0.027 μCi)
ActivityActivity
Biomedical Research uses Ci quantities
Nuclear Medicine uses mCi quantities– Bone Scan uses 25 mCi of Tc-99m
Radiation Oncology uses mCi-Ci quantities– LDR implants use 100-200 mCi of Cs-137– HDR implants use 10 Ci Ir-192
Sources used in Radiation WorkSources used in Radiation Work
Biomedical Research
C-14, H-3, I-125, P-32, S-35
Nuclear Medicine
Tc-99m and I-131
both use unsealed sources
contamination usually biggest problem
Sources Used in Radiation WorkSources Used in Radiation Work
Radiology
x-ray equipment
Oncology
Cs-137, Ir-192, Pd-103, x-ray equip. & linacs
machine and sealed sources
external exposure is the biggest concern
Annual Average Background Annual Average Background Dose DistributionDose Distribution
(total =360 mrem)(total =360 mrem)
Radon55%
Other3%
Terrestrial8%
Cosmic8%
Internal11%
Nuclear Medicine
4%Medical Xrays
11%
Acute Radiation EffectsAcute Radiation Effects
Minor blood changes 25,000 mrem
Hemopoietic Syndrome 200,000 mrem
Erythema 200-300,000 mrem
LD50,30 450,000 mrem
Delayed Radiation EffectsDelayed Radiation Effects
Cancer
Genetic Effects
Extrapolating Risk FactorsExtrapolating Risk Factors
KnownEffects
X X
X
X
X
X
Effect
Radiation Dose
Extra
polated R
isk
OccupationalDose Levels
Dose LimitsDose Limits(10 CFR 20.1201-8)(10 CFR 20.1201-8)
Total Effective Dose Equivalent 5000 mrem
Total Organ Dose Equivalent 50,000 mrem
Lens of the Eye 15,000 mrem
Skin and Extremities 50,000 mrem
Declared Pregnant Worker 500 mrem
Minor 500 mrem
General Public 100 mrem
Declared Pregnant WorkerDeclared Pregnant Worker
a woman who has voluntarily informed her employer, in writing, of her pregnancy and the estimated date of conception.
licensee shall make efforts to avoid substantial variations in monthly exposures
Dosimeter FiltersDosimeter Filters
Open window
Copper
Tin
Image filter
Al2O3 strip
Low energy - static
Radiation
Low energy - dynamic
Radiation
Pregnant PatientPregnant Patient
Get and read Wagner’s book
If clinically indicated, do the study
Steps should be taken to lower dose if possible
When counseling, use numbers that are understandable
Pregnant PatientPregnant Patient
Effective Doses to Patients Effective Doses to Patients from Diagnostic Studiesfrom Diagnostic Studies
DEXA < 1mrem
Chest x-ray ~ 10 mrem
AP abdomen ~ 70 mrem
Upper GI ~ 300 mrem
CT abdomen ~ 700-1000 mrem
Coron. Angioplasty ~ 2200 mremSource: Hall, Radiobiology for the Radiologist, 5th edition
Effective Doses to Patients Effective Doses to Patients from Diagnostic Studiesfrom Diagnostic Studies
4 mCi Tc MAA ~ 160 mrem
15 mCi Tc DTPA ~ 270 mrem
25 mCi Tc MDP ~ 525 mrem
15/40 mCi Tc Mibi ~ 1700 mrem
10 mCi 18F-FDG ~ 700 mrem
15 mCi FDG PET/CT ~2500 mremSource: ICRP 80, Radiation Dose to Patients from Radiopharmaceuticals
Radiation Induced Skin Radiation Induced Skin Injuries from FluoroscopyInjuries from Fluoroscopy
Skin injuries are the most likely injury resulting from diagnostic procedures.
Fluoro unit outputs average to 1-2 R/min
Fluoro unit outputs can go up to 10 R/min
High Dose modes can go up to 20 R/min
No limits on Cine or digital recordings
Transient erythema at 200 rads
Radiation-Induced Skin Injuries [14, 17]
•Skin “burns” are rare but possible for prolonged fluorocardio & other interventions•FDA has received 60 reports of burns since 1994 ~ 8.6 reported burns per year•How many radiation burns are not reported?
Figure from [17]
Example of chronic skin injury due to cumulative skin dose of ~20,000 mGy (20 Gy) from coronary
angiography and x2 angioplasties
21 months after first procedure, base of ulcer exposes spinous process
estimated 25 Gy dose estimated 25 Gy dose Erythemia at 3 weeksErythemia at 3 weeks
Ulceration at 5 monthsUlceration at 5 months
Debridement at 6.5 monthsDebridement at 6.5 months
Nuclear Medicine Authorized Nuclear Medicine Authorized UsersUsers
Requirements in 10 CFR 35
You are NOT an Authorized User UNTIL approved:
• specific license: NRC
• broad scope license: Rad. Safety Committee
Accurate AdministrationsAccurate Administrations
The department must have a program in place to ensure that the following are correct, as directed by the Authorized User:
• patient identity• radiopharmaceutical• dosage
Medical EventMedical Event(formerly misadministration)(formerly misadministration)An administration involving the wrong individual, wrong radiopharmaceutical, wrong route of administration
AND
the dose to the patient >5 rem EDE or 50 rem to any organ.
Medical EventMedical Event(formerly misadministration)(formerly misadministration)An administration to the correct patient when the total dosage > +/- 20% of the prescribed dosage or the prescribed dosage range
AND
the dose to the patient differs by more than 5 rem EDE or 50 rem to any organ than would have resulted from the prescribed dosage.
Medical Event ExamplesMedical Event Examples
1) Therapy dose mishaps are generally medical events
2) Diagnostic dose events are generally not medical events.
General Radiation SafetyGeneral Radiation Safety
External Exposure Control:
• Time
• Distance
• Shielding
Internal Exposure Control
• Contamination prevention
TimeTime
Minimize time spent with patients after being dosed
may not be practical
DistanceDistance
Maximize distance from patient to greatest extent possible
monitor with electronic dosimeter to find where max. dose is received
DistanceDistance
Maximize distance from patient to greatest extent possible
monitor with electronic dosimeter to find where max. dose is received
Distance - exampleDistance - example
From a patient with a typical stress dosage, a worker at edge of treadmill receives about 9 mR/hr.
Distance - exampleDistance - example
At 1 meter from the treadmill, the exposure rate is about 2 mR/hr.
ShieldingShielding
Beta Shielding
low Z material (plexi-glass)
thickness > beta particle range
Gamma Shielding
high Z material
calculate required thickness
Lead ApronLead Apron
Standard apron thickness is 0.5 mm Pb equival.
PA requires at least 0.25 mm.
Attenuation of 0.5 mm Pb:
Cs-137 = 6%
Tc-99m = 74%
x-rays = >95%
Internal Exposure Control:Internal Exposure Control:Contamination PreventionContamination Prevention
Gloves and lab coat
Personnel surveys: hands, feet, clothing
No eating, drinking, smoking, or applying cosmetics in licensed areas.
Make sure all radioactive material containers are properly closed and carefully handled.
InspectionsInspections
Be honest
Answer questions which are asked
Have organized records
EmergenciesEmergencies
Spills are the most common problem
Must have procedures in place
Will demonstrate program weaknesses
SummarySummary
Know the regulationsKnow license requirements and minimize commitmentsKnow the regulatorsGet program supportStay organizedBe honest and admit your mistakes
When in doubt, ask your RSO
RememberRemember
Don’t be the RSO!