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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 Spectrum Waveform 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 Electron Orbital path Atomic Structure Nucleus - center of atom, consists of protons and neutrons Electrons - negatively charged particles that orbit around the nucleus Held together by a ttraction 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 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 X-Ray

12 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. X-Ray

13 Sources of Exposure mrem = millirem

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

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

16 Biological Effects of Radiation Parent cell Cell division Normal cells

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

18 Biological Effects of Radiation 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

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

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 Standards and Guides Why is there a difference between occupational limits and public health limits? Occupational limits  Healthy population  Ages  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

27 Standards and Guides Body Part Exposed Permissible Dose (rem per quarter) Whole body1.25 Hands, forearms, feet, ankles Skin of whole body7.50 OSHA

28 Standards and Guidelines Body Parts Exposed Permissible Dose (rem per quarter) Whole body0.125 Hands, forearms, feet Skin of whole body0.75 OSHA Dose Limits for employees 18 Years and Younger

29 Standards and Guides 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 Posting Requirements

30 Universal symbol Standards and Guides

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. I 1 R 1 2 = I 2 R 2 2

36 Basic Safety Factors I 1 R 1 2 = I 2 R 2 2 Inverse Square Law I 1 = initial intensity R 1 = initial distance R 2 = new distance I 2 = 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? I 2 = I 1 x (R 1 2 / R 2 2 ) I 2 = 5 mR/hour x ( 1ft 2 / 16 ft 2 ) I 2 = 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.