Ionizing Radiation BIOS 1471 – INTRODUCTION TO LABORATORY SAFETY March 21, 2013 Janet M. Gutiérrez, DrPH, CHP, RRPT Radiation Safety Program Manager Environmental Health & Safety

Speaker Biography  Janet M. Gutiérrez is manager of the Radiation Safety Program at The University of Texas Health Science Center at Houston. She is a Certified Health Physicist (CHP) and a Registered Radiation Protection Technologist (RRPT). In August 2011, she received a Doctorate in Public Health from the The University of Texas at Houston School of Public Health (UT SPH), and in 2005, she received a M.S. in Environmental Sciences / Industrial Hygiene from UT SPH as well. In 1998, Janet received a B.S. in Radiological Health Engineering from Texas A&M University in College Station, TX.

Public Health Significance Summary of Radiation Events Causing Acute Injuries or Fatalities in the World from Type of Event IncidentsFatalitiesInjuries Radiotherapy accidents Accidents with power reactors Lost sources Accidents with naval reactors Criticality accidents (non-reactors) Occupational contamination Irradiator accidents 3189 Dispersal of lost sources 2624 Accidents with research reactors 469 Criminal radiological acts 541 Nuclear weapons tests 1193 TOTAL (116) 1,130 Source: Database of radiological incidents by Wm. Robert Johnston, online at

Public Health Significance Goiania, Brazil, Cs-137 Dispersal  Ruptured 1,400 Ci Cs-137 Therapy Source  Glowing powder shared EffectNumber Death4 Internal contamination and radiation skin burns 19 Hospitalized for radiation exposure 54 Found contaminated 244 Identified as dose > 1 year of background radiation 1,000 Persons examined for radiation contamination 112,000

Public Health Significance Fukushima Daiichi Nuclear Power Plants

 Earthquake & Tsunami caused damage at nuclear power plant resulting in loss of water in reactor, meltdown of reactor core & hydrogen explosions. EffectNumber Deaths (estimated) from Earthquake & Tsunami > 25,000 Deaths – nuclear power plant workers (earthquake, tsunami & heart attack) 4 Deaths directly from radiation exposure 0 Hospitalized for radiation exposure 2 Evacuated residents within 20 km (12 mile) zone {US 80 km = 50 mi} Up to 287,000 Persons examined for radiation contamination (e.g. 34,000 school children) “TNTC” Crops & fish examined for radiation contamination (e.g. Cs-137 in rice, Cs-137 in 578 steer, green tea, mushrooms) 1,040 – US FDA

Radiation Safety

Ionizing vs. Non-ionizing Radiation  Electromagnetic Spectrum

Educational Objectives  Become familiar with basic radiation safety concepts  Differentiate between ionizing and non- ionizing radiation  Identify occupational dose limits  Describe typical tasks of a Radiation Safety Program  Describe typical radiation detection techniques  Identify regulatory agency for radioactive material use oversight

Radiation Safety  Radiation Safety or Health Physics is…  Anticipation, recognition, evaluation and control of radiation hazards

Radiation Hazards  Acute or chronic symptoms to overexposure  Ex. Skin reddening  Ex. Increase in risk of skin cancer  Regulatory limit well below symptoms  LNT Model

Anticipation of Common Sources of Radiation  Naturally occurring  Radon  Man-made & non-occupational  As patient to medical procedure  Food-irradiation  Occupational  Research  Medical  Industrial

Anticipation of Common Sources of Radiation

Common Sources On Campus  Radioactive Materials  Research Labs Beta and Gamma Beta and Gamma  Diagnostic Medicine  Static Eliminators (precision balances)  X-ray fluorescence analytical tools  Liquid Scintillation Counters  Moisture/Density Gauge  Radiation-Producing Devices  Diagnostic Medicine  Dental Clinic  Anatomy Lab  Electron Microscope  Particle Accelerator  Student Health Clinic

Common Sources On Campus  High-Powered Lasers  Physics Labs  Particle Counters  Confocal Microscopes  Dermatology Dept.  Tattoo Removal  Dental Clinic  Electric/Magnetic Fields  MRI/NMR  Machinists  Electricians  Welders

Recognition of Radiation Sources  Labeling  Certain exemptions  Radiation detection

Evaluation of Radiation Hazards  Portable detector to measure exposure  Dosimetry to measure exposure  Survey for contamination  Removable  Fixed

Radiation Control or Permit  Granted by  Nuclear Regulatory Commission  Or Agreement State (e.g. Texas Department of State Health Services Radiation Control)  Permit for  Radioactive material = license Specific license vs. broad license Specific license vs. broad license  Radiation producing device = registration X-rays and Lasers X-rays and Lasers

Radiation Safety Program  Radiation Safety Officer (RSO)  Radiation Safety Committee * * Requirement depends upon type of permit * Requirement depends upon type of permit  Fundamental purpose  “maintain radiation doses as low as reasonably achievable” (ALARA)

What are Duties of RSO?  Minimum duties listed in…  25 TAC § (f)(3) {for Radioactive Material} ﻬ Operating, safety, emergency procedures ﻬ Training ﻬ Surveys (contamination & leak tests) ﻬ Dosimetry ﻬ Report events resulting in exposure > limit ﻬ Report accidental radiation release in excess of limits ﻬ Familiar with policy & procedures of license ﻬ Ensure proper labeling, storage and use of radiation ﻬ Ensure inventories are within license limits ﻬ Perform inventory and leak test of sealed sources every 6 months ﻬ Ensure personnel comply with regulations & license conditions ﻬ Be primary contact to (Bureau of) Radiation Control

What requirements does a RSO have to follow?  Rules / Regulations  Permit Conditions  Tie Downs

Where can I go for help?  Nuclear Regulatory Commission   State Regulatory Commission   National Health Physics Society   Local Health Physics Society   Texas Radiation Control 

Radiation and Radioactivity  Radiation = emission and propagation of energy through space or through a material in the form of waves or, by extension, corpuscular emissions  Radioactivity = spontaneous emission of radiation from the nucleus of an unstable atom

Basic Concepts  Radiation: energy  Ionizing vs. Non-Ionizing: enough energy to eject orbital electrons  Radioactivity: excess nuclear energy

Radioactivity  Radioactivity is the natural property of certain nuclides to spontaneously emit energy, in the form of ionizing radiation, in an attempt to become more stable.

Nomenclature  A = mass number = Z + N  total number of protons + neutrons  N = number of neutrons  Z = atomic number  number of protons  X = element

Chart of the Nuclides

Basic Concepts  Radionuclide  Nuclide  Isotopes have the same Z and a different A;  10 C, 11 C, 12 C, 13 C, 14 C  Isobars have the same A and a different Z;  14 N, 14 O; 15 N, 15 C  Isomers have the same A and the same Z;  99m Tc, 99 Tc  Isotones have the same N and a different A;  14 O, 13 N, 12 C, 11 B, 10 Be, 8 Li

Basic Concepts  Types of radiation:  Alpha: particulate, massive  Beta: particulate, penetrating  Gamma & X-ray : electromagnetic, penetrating  Neutron: particulate, no charge

Alpha (α)  Needs at least 7.5 MeV energy to penetrate nominal protective layer of skin (7 mg/cm 2 )  Most α less than this energy, so can not penetrate skin  Range in air  Range (cm) = 0.56E for E< 4 MeV  Range (cm) = 1.24E-2.62 for E> 4 MeV

Beta (β)  Need at least 70 keV energy for beta to penetrate nominal protective layer of skin  β ave = 1/3 β max  Range in air  Range is ~ 12 ft / MeV  Bremsstrahlung for high energy beta & high Z material  Ex. P-32 and Lead

Gamma (γ)  Photoelectric  Compton Scattering  Pair Production  Photon  X-ray  Gamma ray

Neutrons (n)  Often expressed in n / cm 2 sec  Thermal neutrons = eV  Slow neutrons = 1 eV – 10 eV  Fast neutrons = 1 MeV – 20 MeV  Relativistic neutrons = > 20 MeV  U-238 & U-235

Shielding Examples

Minimizing Radiation Dose Keeping Radiation Doses ALARA  ALARA = As Low As Reasonably Achievable  Reduce time near radionuclide  Stay time = dose rate * time  Increase distance from radionuclide  Reduction follows inverse square law Triple distance from source Triple distance from source = 1/9 of original dose = 1/9 of original dose  Add appropriate shielding  Reduction based on density & atomic number of shielding material and energy of emitted radiation  Use less

Common Units DefinitionUnit* RadioactivityRate of decay or transformation from unstable radionuclide towards stability Curies (Ci) Becquerel's (Bq) ExposureA measure of charge per mass emitted for photons in air Roentgen (R) Coulomb / kilogram (C/kg) Absorbed DoseEnergy deposited by ionizing radiation in a unit mass of material Roentgen Absorbed Dose (rad) Gray (Gy) Dose EquivalentMeasure of the relative hazards of various types of radiation Rem (Roentgen Equivalent Man) Sievert (Sv) * USA Units, SI (International Units)

Common Units ConversionUnit* RadioactivityCuries (Ci) Becquerel's (Bq) ExposureRoentgen (R) Coulomb / kilogram (C/kg) Absorbed Dose 1 Gy = 100 rad Roentgen Absorbed Dose (rad) Gray (Gy) Dose Equivalent 1 Sv = 100 rem Rem (Roentgen Equivalent Man) Sievert (Sv) * USA Units, SI (International Units)

Quality Factors  Quality Factor (Q) used for converting absorbed dose to dose equivalent 25 TAC § (n)(1)  Q type x # rad = # rem  20 α x 2 rad = 40 rem for alpha radiation

What do we really need to know?  1 R  1 rad = 1 rem For gammas & betas For gammas & betas  1 rad  1 rem For alphas, neutrons & protons For alphas, neutrons & protons 1 rem = 1 rad x Q 1 rem = 1 rad x Q

 Half-life - the amount of time required for 1/2 of the original sample to decay  The half-life is constant for each radionuclide and varies due to the nuclear structure. Half-life

Radioactive Decay Is the process by which the amount of activity of a radionuclide diminishes with time. Examples:

Radioactive Decay Formula Variables Variables A  Activity at time t A  Activity at time t A 0  Original Activity A 0  Original Activity t  Time t  Time  Decay Constant  Decay Constant T 1/2  Half Life Constants Constants ln 2  e 1  e 1  2.718

Concepts  Radioactive Decay: A = A o e -λt A = λN A = λN λ = / T 1/2 λ = / T 1/2  Inverse Square Law  Shielding I = I o Be -  t

Annual US Average Dose from Background Radiation was Total US average dose equivalent = 360 mrem/year Total exposure Man-made sources Radon Internal 11% Cosmic 8% Terrestrial 6% Man-Made 18% 55.0% Medical X-Rays Nuclear Medicine 4% Consumer Products 3% Other 1% 11%

Annual US Average Dose from Background Radiation Now is 625 mrem National Average Dose is US is 625 mrem, with medical being the largest type of increase. Source NCRP 160

Monitoring  Instrumentation  Gas filled  Solid scintillator  Liquid scintillation

Monitoring  Dosimeters  Film badges: beta, gamma, x-ray Permanent record Permanent record Subject to fading Subject to fading  Thermoluminescent dosimeter (TLD): beta, gamma, x-ray No permanent record No permanent record Can be used for long term use Can be used for long term use  Pocket ion chamber: gamma, x-ray Immediate readout Immediate readout Shock sensitive Shock sensitive

Biological Damage  Radiation may…  Deposit Energy in Body  Cause DNA Damage  Create Ionizations in Body Leading to Free Radicals Leading to Free Radicals  Which may Lead to Biological Damage

Two Types of Biological Effects  Stochastic effects (chance)  Dose increases the probability of the effect  No threshold  Any exposure has some chance of causing the effect  Cancer  Non-stochastic effects (threshold)  Dose increases the severity of the effect  Threshold  Effects result from collective injury of many cells  Reddening, cataract, skin burn

Biological Effects  Assumptions Used for Basis of Radiation Protection Standards  No Threshold Dose, Risk with Given Dose Increases With Increasing Dose Received, Acute vs. Chronic Exposures Not Considered, i.e. Repair  Most conservative

Biological Effects  Prenatal Exposures  Law of Bergonie & Tribondeau (1906): Cells Tend to be Radiosensitive if They Have Three Properties: Cells Tend to be Radiosensitive if They Have Three Properties: A) Have a High Division Rate A) Have a High Division Rate B) Have a Long Dividing Future B) Have a Long Dividing Future C) Are of an Unspecialized Type C) Are of an Unspecialized Type

Most and Least Radiosensitive Cells Low Sensitivity Mature red blood cells Muscle cells Ganglion cells Mature connective tissues High Sensitivity Gastric mucosa Mucous membranes Esophageal epithelium Urinary bladder epithelium Very High Sensitivity Primitive blood cells Intestinal epithelium Spermatogonia Ovarian follicular cells Lymphocytes

Acute Radiation Syndromes  Occurs if specific portions of body are exposed  Not likely unless major organs involved  3 ARS syndromes:  Hematopoietic (blood/bone marrow) rad rad Treatment: transfusions, antibiotics, bone marrow transplant Treatment: transfusions, antibiotics, bone marrow transplant  Gastrointestinal (intestinal lining) rad rad Death likely if dose >1000 rad Death likely if dose >1000 rad Treatment: make individual comfortable Treatment: make individual comfortable  Central Nervous System (brain) 2000 rad or more 2000 rad or more Death likely within days Death likely within days Treatment: make individual comfortable Treatment: make individual comfortable

LD 50 for Humans  Dose of radiation that would result in 50% mortality of in the exposed population within 30 days of exposure with NO medical treatment  LD 50 for Humans is 300 to 500 rad

Risks of Radiation Exposure  Low level (< 10,000 mrem) radiation  Only health effect: cancer induction  Average occupational dose to research and lab medicine personnel: <10 mrem/yr  Amount is comparable to: 6 cigarettes/yr 6 cigarettes/yr Driving 1,000 miles Driving 1,000 miles Living in a stone or brick home for 2 months Living in a stone or brick home for 2 months

Regulations / Guidelines Regulations  NRC  Agreement States  Ex. Texas Radiation Control Guidelines  NCRP  ICRP  IAEA

Exposure Limits  Regulations: NRC 10 CFR 20  Note old:  Whole body: 1.25 rem/quarter  Skin: 7.5 rem/quarter  Extremities rem/quarter  New:  Committed Dose Equivalent (CDE) Dose to a particular organ: Dose to a particular organ: ﻬ Internal + External ≤ 50 rem

Annual Exposure Limits Whole Body = Total Effective Dose Equivalent General Public Limit = 2 mrem / hr or 0.1 rem / yr remmrem Whole-Body55,000 Eye1515,000 Shallow5050,000 Minors & Declared Pregnant Workers* 10 %

Exposure Limits  Total Effective Dose Equivalent (TEDE) Sum of dose from external and internal, including weighting: Sum of dose from external and internal, including weighting: ﻬ Internal + External ≤ 5 rem  Effective Dose Equivalent Dose to organ or organs over one year period Dose to organ or organs over one year period  Total Organ Dose Equivalent Dose to organ from both internal and external: Dose to organ from both internal and external: ﻬ Internal + External ≤ 50 rem  Exposure to Fetus (Declared Pregnancy) 0.5 Rem/9 months

Dosimetry Program  Monitors occupational exposures to employees above background radiation levels  Employee’s medical exposures are not included  General public or visitor exposures  Required to Monitor if the individual is “likely to exceed 10% of dose limit.”

Who Needs Dosimetry?  Those “likely” to exceed 10% of their annual limit are required  Minors & declared pregnant workers  Those who would like a badge?

Bioassays: Thyroid and Urine To asses internal dose

Other Useful Information  6CE rule of thumb  Efficiency = c/d, usually in percent  Effective half life:  Stay time = dose / dose rate  REMEMBER UNITS!

Common Radionuclides  Sealed sources  Cs-137, Co-60, Ir-192, Am-241, Kr-85, Sr-90, Po-208  Liquid radioactive material for research  P-32, P-33, S-35, H-3, C-14

Inventory Tracking  Maximum activity for radionuclide in specific form  5 Ci of C-14 in solid or liquid  500 Ci of Cs-137 for irradiator SN ###  Broad application  Any radionuclide with atomic number less than 84  1 Ci of any radionuclide, 20 Ci total  Database  Log  Researcher log

Typical Things to Look for in a Radiation Lab

Radiation Safety Program / RSO May…  ALARA program  Maintain dosimetry  Ship/receive radioactive materials  Perform audits of sub- licensees  Track deficiencies  Maintain radiation inventory  Training  Security  Perform leak test of sealed sources  Declared pregnancy program  Perform bioassays as needed  Incident investigation  Radiation decontamination  Environmental monitoring  Authorize radiation use or storage areas  Provide guidance / oversight with radiation protocols  Convey regulatory information  Keep current with developments in the field  Waste processing & disposal

Radiation Safety Training

Training  Minimum training for radioactive material listed in 25 TAC (jj) (1)  Time, topics, refresher requirements specific to license  Radionuclide specific  Generic training

Radioactive Material Packages

Shipments of Radioactive Material  Class 7  Activity & Transport Index  Differences from other Hazardous Materials Shipping regs  Receiver needs training, too – not just shipper  Inspections possible by state, DOT and FAA  Wipes on all packages and surface readings on some packages are required  Readings by a calibrated dosage meter  Emergency response number (answered 24- hrs/day) must be provided

Surveys for Radiation Contamination

Spill Cleanup  Inform Coworkers  Limit Traffic  Blot liquid  Decontaminate Re-asses Label if “fixed” Document RC Notification?

Spills / Incidents  Assist in decontamination procedures  Survey area post de-con to ensure the area is sufficiently cleaned  Incident investigation report  Contact DSHS RC (regulatory agency) if needed  Perform bioassay if internal exposure suspected

Emergency Response

Radiation Decontamination

Lunch Break?

Lunch Break  Do not mix radiation and food  After Lunch  Define and demonstrate basic detection concepts  Labs 1- α, β, γ, 2 – Trouble shooting, 3 – Efficiencies 1- α, β, γ, 2 – Trouble shooting, 3 – Efficiencies  Radiation Problems  Review Important Concepts

Radiation Detection

 Identify exposure to personnel, patients or general public  Assess removable contamination  Assess fixed contamination  Identify “hot” or contaminated areas of room  For tracers, identify how much has gone through certain process

Ionization of Gas – Radiation Detector  A = recombination  B = ionization  C = proportional  D = limited proportional  E = Geiger Muller  F = continuous discharge

Radiation Detectors  General Classes of Radiation Detectors  Gas-Filled Detectors Geiger-Mueller †, Ion Chamber, Proportional Counter Geiger-Mueller †, Ion Chamber, Proportional Counter  Liquid Detectors  Solid Detectors † Geiger-Mueller (GM) detectors are common

Removable Contamination Detection Liquid Scintillation Counter

Radiation Detectors

Question?  32 P  51 Cr  86 Rb  3 H Why? How do you detect 3 H?

Questions  Should I monitor with red cap?  Why are the probes covered in plastic wrap?  At what level is something considered contaminated?  How often should portable detectors be calibrated?

Radiation Lab Exercises

Radiation Practice Problems Ionizing Radiation

Radiation Practice Problems  1. Iodine-131 has a radiological half life of 8 days. If a source originally contained 25 mCi how much remains after 18 days?

Radiation Practice Problems  2. Two measurements are taken on an unknown radiation source. The first was 1.3 mCi, and the second, taken 15 minutes later, was 0.05 mCi. What is the half life of this material?

Radiation Practice Problems  3. What is the exposure rate from a 15 Ci Cs-137 source at a distance of 1 foot? (Cs- 137 gamma energy MeV) How about 10 feet?

Radiation Practice Problems  4. How long can a worker stay 10 feet away from a 15 Ci Cs-137 source without exceeding an administratively established quarterly dose limit of 1250 mrem?

Review of Important Radiation Safety Concepts

 Average annual exposure to an individual in the U.S. due to background radiation is 620 mrem per year  In order to achieve exposures As Low As Reasonably Achievable (ALARA), you should minimize the time spent around radioactive material, maximize the distance between you and the source, and use proper shielding  Radioactivity is measured in units of Curies (Ci) and Becquerels (Bq)  A portable GM counter (Geiger-Mueller counter) cannot detect 3 H (Tritium)

 The biological effects due to radiation depend on radiation type, dose and dose rate, and portion of body irradiated  The rationale for reducing the amount of exposure to the fetus is the fetus is very radiosensitive  The maximum annual whole body dose limit for an occupationally exposed individual is 5 rem or 5,000 mrem  Personal dosimetry badges are only required for persons likely to exceed 10% of any legal limit

 When working with radioactive isotopes, personal protective measures include laboratory coats and gloves  Eating, smoking, drinking, or the storage of food, beverage or tobacco products in radioactive material area is prohibited because it increases the possibility of internal contamination  When using a GM survey instrument to check for contamination, the probe should be moved slowly and near contact with the surface