Ionizing & Non-ionizing Radiation ENGR 4410 – INDUSTRIAL HYGIENE INSTRUMENTATION October 23, 2013

1. Ionizing & Non-ionizing RadiationENGR 4410 – INDUSTRIAL HYGIENE INSTRUMENTATIONOctober 23, 2013 Janet M. Gutiérrez, DrPH, CHP, RRPT Radiation Safety Program Manager Environmental Health & Safety 713-500-5844 Janet.R.McCrary@uth.tmc.edu

2. Speaker Biography • Janet M. Gutierrez 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.

3. Speaker Biography • Travis Halphen is a Safety Specialist in the Radiation Safety Program at The University of Texas Health Science Center at Houston (UTHSC-H). He is currently seeking his MPH in Environmental Health and Occupational Safety from University of Texas School of Public Health (UT SPH) and on May 2006 he received a Bachelors in Medical Physics from Louisiana State University. He was Assistant Radiation Safety Officer and Laser Safety Officer at Kansas State University from 2006 to 2008 before he ended up at his current position at UTHSC-H

4. Ionizing vs. Non-ionizing Radiation • Electromagnetic Spectrum

5. Radiation

6. Ionizing & Non-ionizing Radiation • Units • Decay • Inverse Square Law • Shielding, HVL, TVL • Instruments • Dosimetry • Biological Effects • Regulations • Practice Problems • Types • Biological Effects • Regulations/Guides

7. What is Radiation? • Radiation is energy transmitted by particles or electromagnetic waves • Radiation can be ionizing or non-ionizing

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

9. 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.

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

12. Basic Concepts • Types of radiation: • Alpha: particulate, massive • Beta: particulate, penetrating • Gamma: electromagnetic, penetrating • X-ray: electromagnetic, penetrating • Neutron: particulate, no charge

13. Alpha (α) • Needs at least 7.5 MeV energy to penetrate nominal protective layer of skin (7 mg/cm2) • 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

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

15. Gamma (γ) • Photoelectric • Compton Scattering • Pair Production • Photon • X-ray • Gamma ray

16. Neutrons (n) • Often expressed in n / cm2sec (flux) • Thermal neutrons = 0.025 eV • Slow neutrons = 1 eV – 10 eV • Fast neutrons = 1 MeV – 20 MeV • Relativistic neutrons = > 20 MeV • U-238 & U-235

17. Shielding Examples

18. Shielding for Multiple Types of Radiation • High Energy Betas • Bremstrahlung • Neutrons • Gammas

19. Units • Activity: Curie (Ci) 3.7 x 1010 disintegrations per second • SI: Becquerel 1 dps • Exposure: Roentgen • SI: C/kg • Absorbed Dose: Rad (Roentgen Absorbed Dose) • SI: Gray, 1Gy = 100 Rad • Risk: Rem (Roentgen Equivalent Man), Rad x QF • SI: Sievert, 1 Sv = 100 Rem

20. Quality Factors

21. Half-life • 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.

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

23. Radioactive Decay Formula Variables A  Activity at time t A0  Original Activity t  Time   Decay Constant T1/2 Half Life Constants ln 2  0.693 e1 2.718

24. Concepts • Radioactive Decay: A = Aoe-λt • A =λN • λ = 0.693 / T1/2 • Inverse Square Law • Shielding I = IoBe-t

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

26. 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.

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

28. Monitoring • Instrumentation • Gas filled • Solid scintillator • Liquid scintillation

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

30. Biological Effects • Radiation Effects on Cells: • Somatic (early, delayed) & • Genetic Dose Responses • Linear, Linear Quadratic, Threshold

31. Stochastic and Non-stochastic Effects • Stochastic effects • Dose increases the probability of the effect • No threshold • Any exposure has some chance of causing the effect • Cancer • Non-stochastic effects • Dose increases the severity of the effect • Threshold • Effects result from collective injury of many cells • Reddening, cataract, skin burn

32. 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

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

34. Most and Least Radiosensitive Cells

35. Acute Radiation Syndromes • Occurs if specific portions of body are exposed • Not likely unless major organs involved • 3 ARS syndromes: • Hematopoietic (blood/bone marrow) • 100-700 rad • Treatment: transfusions, antibiotics, bone marrowtransplant • Gastrointestinal (intestinal lining) • 500-2500 rad • Death likely if dose >1000 rad • Treatment: make individual comfortable • Central Nervous System (brain) • 2000 rad or more • Death likely within days • Treatment: make individual comfortable

36. LD50 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 • LD50 for Humans is 300 to 500 rad

37. 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 • Driving 1,000 miles • Living in a stone or brick home for 2 months

38. Regulations / Guidelines • NRC • Agreement States • NCRP • ICRP • ALARA Program

39. Exposure Limits • Regulations: NRC 10 CFR 20 • Note old: • Whole body: 1.25 rem/quarter • Skin: 7.5 rem/quarter • Extremities 18.75 rem/quarter • New: • Committed Dose Equivalent (CDE) • Dose to a particular organ: • Internal + External ≤ 50 rem

40. Exposure Limits • Committed Effective Dose Equivalent (CEDE) • Dose to a particular organ or organs with weighting factor: • Internal + External ≤ 5 rem • Deep Dose Equivalent (DDE) • Dose at a depth of ≥ 1 cm: • Internal + External ≤ 5 rem (Eye ≤ 15 rem) • Shallow Dose Equivalent (SDE) • Dose to skin or extremity: • External ≤ 50 rem

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

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

43. http://www.icrp.org • Internal advisory body for ionizing radiation • ICRP Publications (examples) • ICRP 84, Pregnancy and medical radiation • ICRP 85, Interventional radiology • ICRP 86, Accidents in radiotherapy • ICRP 87, CT dose management • ICRP 93, Digital radiology

44. National Council on Radiation Protectionand Measurements • http://www.ncrponline.org • formulate and widely disseminate information, guidance and recommendations on radiation protection and measurements which represent the consensus of leading scientific thinking • publication of NCRP materials can make an important contribution to the public interest. • NCRP 148 – Radiation Protection in Veterinary Medicine • NCRP 138 – Management of Terrorist Events Involving Radioactive Material* • NCRP 134 – Operational Radiation Safety Training • NCRP 120 – Dose Control at Nuclear Power Plants • NCRP 115 – Risk Estimates for Radiation Protection

45. Control Programs for Sources of Radiation • Sealed Sources • Radiation-Producing Machines • Radioisotopes • Radioactive Metals • Criticality • Plutonium

46. Control Programs for Sources of Radiation • Operational Factors • Employee Exposure Potential • External Hazards • Internal Hazards • Records

47. 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

48. Radiation Practice ProblemsIonizing Radiation

49. 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?

50. 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?