How to Work Safely Around Radiation Sources and Lasers (in less than 1 hour)

1. How to Work Safely Around Radiation Sources and Lasers (in less than 1 hour) Dr. James F. Schweitzer Radiation Safety Officer

2. Radioactivity • Spontaneous emission of particles and/or electromagnetic radiation from an unstable nucleus • Alpha particles • Beta particles • Gamma Rays • Neutrons

3. History • 1895 - Roentgen discovers x-rays • 1896 - Becquerel discovers radioactivity • 1898 - Curie discovers radium • 1904 - First death attributed to cumulative overexposure • 1915 - First radiation protection recommendations adopted • 1958 - Maximum permissible annual dose equivalent - 5 rem

4. Types of Radioactivity • Naturally Occurring • Uranium and Thorium decay series • Potassium - 40 • Continually produced : Tritium and Carbon - 14 • Artificially Produced • Accelerators • Reactors (Byproduct material)

5. Uses of Radioactivity • Radiotracer applications • Activation by particle irradiation • Irradiation and sterilization • Medical diagnosis and therapy

6. Regulation of Radioactive Material • Nuclear Regulatory Commission (NRC) • Byproduct material • Reactors • Special Nuclear Material and Source Material • State Radiological Health (ISDH) • Machine produced • Accelerator produced • Naturally occurring

7. Requirements for Radioactive Material Use • Purdue Training • Completion of Proper Paperwork (A-4) • Adherence to Protocols Previously Submitted by PI • Training by Designated Individual • Keep Track of Material: SECURITY, INVENTORY, SURVEY

8. Available Training • Unsealed Radioactive Material • Sealed Radioactive Sources (Includes irradiator) • Diagnostic X-ray( includes DEXA) • Analytical X-ray • Laser Safety

9. Exposure Limits • Effective dose equivalent - 5 rems • Dose equivalent to any organ - 50 rems • Shallow dose equivalent (skin) or dose to the extremities - 50 rems • Eye dose equivalent - 15 rems • Declared pregnant worker - 0.5 rems • Minor - 10% of adult levels • 1 rem = 1000 millirem

10. As Low As Reasonably Achievable The philosophy that reasonable efforts are maintained to keep radiation exposures as far below the limits as is practical.

11. Methods to Reduce Radiation Exposure • Time - Plan experiments, use as little radioactivity as possible • Distance - Use remote handle devices, remain away from storage areas • Shielding - store stock vials in a shield • Contamination Control - survey work area and self after use, wear PPE

12. Fly from NY to LA Get chest x-ray Move from DC to Denver Live in certain sections of Brazil Get married Eat bananas and nuts 2 millirem 10 millirem 75 millirem/yr Up to 640 millirem/yr 1 millirem/yr ? Measures to Increase Radiation Exposure

13. X-ray Fundamentals Current X-rays e- e- e- e- Potential ( ~ 60 keV ) Target (typ. W or Cu)

14. Characteristic Continuous Voltage X-ray Spectrum • X-rays are created by the deceleration of electrons in a target material • Two types of spectra • Continuous • Characteristic

15. Analytical X-ray Systems • System types • Open beam • Closed beam • Cabinet • Uses • Crystal structure analysis • Virus/protein structure analysis • Composite/alloy integrity

16. Analytical X-ray Hazards • Low energy • Less than 40 keV • Very intense x-ray beam • 400,000 R/minute • Very narrow beam • Typically < 1 mm2 • Minimal scatter • Low energy, absorbed readily in air

17. Energy Dependence of Biological Effects • Low energy x-rays (< 50 kVp) • easily absorbed • produce surface (skin) effects • High energy x-rays (> 50 kVp) • capable of penetrating deep into the body • produce internal effects

18. Specific Hazards • Primary Beam • Very intense x-ray beam • Up to 400,000 R/min • Beam diameter < 1cm • Scatter Radiation • Low intensity • Large area • Leaks through tube housing • Scatter from any point in an absorber

19. Intense X-ray Beam X-ray Tube Detector 400,000 R Shutter Sample Collimator

20. General Safety Mechanisms • Radiation exposure is monitored by a personal radiation dosimeter • Area surveys are performed regularly • GM meter: Where are the leaks? • Ion chambers: How much is leaking? • Room posted with appropriate warning signs

21. Safety Features • Tube housing • Beam shutter • Beam collimation • Primary beam stops • Warning lights (e.g. X-ray on, shutter open) • Standard Operating Procedures (SOPs) • Shielding from entry into primary beam • Annual surveys of equipment

22. LASER • Acronym for Light Amplification by the Stimulated Emission of Radiation • Monochromatic • Collimated (Parallel) -- Focuses to a Point • Coherent • Pulsed or continuous wave

23. MAIN POINTS OF ANSI Z136.1 (1993) • Provides guidance for safe use of lasers and laser systems • Establishes laser hazard classification, 1 to 4, • Evaluates hazards and establishes control measures • Lists requirements for medical surveillance and training programs • Addresses ancillary hazards other than radiation

24. MAIN POINTS OF ANSI Z136.1 (1993) • Specifies maximum permissible exposure (MPE): • Eye • Skin • Diffuse reflection • Classification determined from MPE • Determines the nominal hazard zone (NHZ)

25. Laser Hazard Classification • Laser classification is based on the inherent capability of causing injury. The actual risk of injury will depend on how the laser is used. Important parameters are the laser wavelength and accessible power output of the laser.

26. Laser Hazard Classes ClassDescription • I Not hazardous • II Hazardous only when stared at for long periods of time • III Hazardous for intrabeam viewing and viewing specular reflections • IV Hazardous for intrabeam viewing and viewing diffuse reflections

27. Laser Reflections Specular (“mirror-like”) No reduction in beam intensity. Beam intensity reduced as the inverse square of distance from reflecting surface. Diffuse

28. Mechanisms of Eye Injury • Thermal • charring, edema, hemorrhage • Photochemical (blue light and UV) • produces toxins and biochemical changes causing inflammation, lesions and lens opacities • Photoacoustic (short intense pulses) • explosive forces due to expanding gases

29. Eye Hazard vs. Wavelength UVC UVB UVA VISIBLE IRA IRB IRC 100 200 315 400 700 1400 3000 Lens Retina Lens Cornea Cornea Photochemical Thermal

30. Lasers -- Non-Beam Hazards • Electric Shock • Chemical Exposures • Cryogenic materials • Compressed Gases • Explosions • Laser Generated Air Contaminants (LGAC’s) • Other Hazards

31. Control MeasuresNominal Hazard Zone (NHZ) • Specifies the area(s) of the workroom where direct or scattered laser radiation is considered hazardous. • Exposure levels any place outside the NHZ are not considered hazardous.

32. Control MeasuresNominal Hazard Zone (NHZ) NHZ

33. Class 3b and 4 Procedural ControlsEye Protection • Require and enforce the use of eye protection, specific to the laser, when exposure above the MPE is possible. • Eyewear is wavelength dependent -look for markings!

34. Class 3b and 4 ControlsPanic Button • A remote interlock connector to shut down power to laser system in an emergency, “panic button” Panic Button

35. Class 3b and 4 ControlsWarning Signs • Laser use areas must be posted with appropriate warning signs

36. Class 3b and 4 ControlsEntry Controls Must prevent people from inadvertently or casually entering the laser use area. Types of entry control: • Locked entry • Latched entry • Barriers with signs Secondary Barrier

37. Class 3b and 4 ControlsWindow Coverings • Have all windows, doorways, and open portals covered to prevent transmittance of beam Opaque Window

38. Other Controls • Specify controlled area and limit access • Develop and follow SOPs, especially during the alignment process • Review new procedures and new installations • Prevent unauthorized use of laser • Provide training for all users