Radiation Safety

2. Radiation Safety

3. What is Radiation? • Radiation is a form of energy. • It is emitted by either the nucleus of an atom or an orbital electron. • It is released in the form of electromagnetic waves or particles.

4. The Electromagnetic SpectrumWaveform of Radiation

5. What is the difference between ionizing and nonionizing radiation? • Energy levels: • Ionizing radiation has enough energy to break apart (ionize) material with which it comes in contact. • Nonionizing radiation does not.

6. Nucleus Orbital path Electron Atomic Structure • Nucleus - center of atom, consists of protons and neutrons • Electrons - negatively charged particles that orbit around the nucleus • Held together by attraction of unlike charges

7. Types of Ionizing Radiation • Important in healthcare setting • Alpha particles • Beta particles • Gamma rays • X-rays • Neutrons

8. Sources of Exposure • Naturally occurring sources • Environmental radiation • Medical procedures • Occupational sources

9. Sources of Exposure • Environmental radiation • Fallout from nuclear weapons testing • Effluents from nuclear facilities • Emissions from consumer products (televisions, smoke detectors)

10. Sources of Exposure • Medical sources • X-rays checking for broken bones • Imaging with radioactive material • Tumor treatments • Exposures well controlled • Limited to very specific areas on body

11. X-Ray • Penetrating electromagnetic waves • Originate in outer part of atom • Common example: type used in medical procedures • Energy inversely proportional to wavelength • The shorter the wave, the stronger the energy

12. X-Ray • Penetration distance depends on energy of radiation and the material being irradiated. • Steel needs high energy • Human body needs low energy • Rays come from outside the body but cause damage inside the body.

13. Sources of Exposure mrem = millirem

14. Background exposure is approximately 360 mrem/year Effects on body depend on: Type of radiation Energy of radiation Length of time in body Biological Effects of Radiation

15. Gamma or x-ray Beta Alpha Biological Effects of Radiation Effects from external sources depend on penetrating ability.

16. Parent cell Cell division Normal cells Biological Effects of Radiation

17. Parent cell Irradiated cell Cell division Cells damaged Biological Effects of Radiation

18. Somatic Affects cells originally exposed Affects tissues, organs, possibly entire body Effects range from slight skin reddening to death (acute radiation poisoning) Genetic Affects cells of future generations Keep levels as low as possible Biological Effects of Radiation

19. Biological Effects of Radiation MOST SENSITIVE fetal cell blood cells intestinal cells bone marrow cells sperm cells capillary cells muscle cells nerve cells LEAST SENSITIVE

20. Biological Effects of Radiation • Sources of health hazard data: • Early radiation workers • Medical personnel • Patients treated with radiation • Radiation accident survivors

21. Units of Measurement • Quantity or concentration of radiation • Absorbed dose (rad) • Dose equivalent man (rem) • Radiation exposure (R)

22. Roentgen (R) Exposure to x-rays and gamma rays in air is expressed in roentgens (R)

23. Radiation Adsorbed Dose • rad • Amount of energy released to matter when radiation comes into contact with it • Expressed in rad

24. Radiation Equivalent Man • rem • Injury from radiation depends on amount of energy imparted to matter • Expressed in rem • Some types of radiation produce greater effects than others • Alpha particles produce more energy than beta particles

25. Units of Measurement • Effect of ionizing radiation is determined by: • Energy of radiation • Material irradiated • Length of exposure • Type of effect • Delay before effect seen • Ability of body to repair itself

26. Occupational limits Healthy population Ages 18 - 65 8 hr per day 350 days per year Public health limits Healthy and sick All age groups 24-hr per day 365 days per year Dose limits Standards and Guides Why is there a difference between occupational limits and public health limits?

27. Body Part Permissible Dose Exposed (rem per quarter) Whole body 1.25 Hands, forearms, feet, 18.75 ankles Skin of whole body 7.50 Standards and Guides OSHA

28. Standards and Guidelines OSHA Dose Limits for employees 18 Years and Younger

29. Radiation area 5 mrem in 1 hour or 100 mrem over any 5 consecutive days High radiation area 100 mrem in 1 hour Areas to be labeled Radiation areas High-radiation areas Airborne radioactivity areas Storage and use areas Containers Standards and Guides Posting Requirements

30. Standards and Guides Universal symbol

31. Monitoring Instruments • Personal monitoring • Area monitoring • Surface monitoring

32. Monitoring Instruments • Personal monitoring: • Film badges, rings • Pocket dosimeter

33. Basic Safety Factors • Keep exposures As Low As Reasonably Achievable (ALARA) • Time • Distance • Shielding

34. Basic Safety Factors • Time: • Keep exposure times to a minimum • Minimizes dose • ALARA

35. Basic Safety Factors • Distance: • Inverse square law: by doubling the distance from a source, the exposure is decreased by a factor of 4. I1R12 = I2R22

36. Basic Safety Factors Inverse Square Law I1R12 = I2R22 I1 = initial intensity R1= initial distance R2 = new distance I2 = new intensity

37. Basic Safety Factors Inverse Square Law If a source emits 10 mR/hour at a distance of 1 foot, what is the exposure level at 4 feet away? I2 = I1 x (R12 / R22) I2 = 5 mR/hour x ( 1ft2 / 16 ft2) I2 = 0.625 mR/hour

38. Basic Safety Factors • Shielding: • Encloses the source or isolates workers from the radioactive environment • Must choose the appropriate shielding material, depending on the type of radiation present

39. Basic Safety Factors • Shielding

40. Basic Safety Factors • Shielding

41. Nonionizing Radiation • Sun • Lasers

42. Biological Effects • The eyes are very susceptible to damage from laser light. • Laser emits either: • Infrared (IR) light • Ultraviolet (UV) light

43. Safety Factors • Safety glasses are made for a specific wave length of laser light. • IMPORTANT: Use only the appropriate safety glasses for the laser that you are around.