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Radiation Safety. 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. The Electromagnetic Spectrum Waveform of Radiation.
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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.
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.
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
Types of Ionizing Radiation • Important in healthcare setting • Alpha particles • Beta particles • Gamma rays • X-rays • Neutrons
Sources of Exposure • Naturally occurring sources • Environmental radiation • Medical procedures • Occupational sources
Sources of Exposure • Environmental radiation • Fallout from nuclear weapons testing • Effluents from nuclear facilities • Emissions from consumer products (televisions, smoke detectors)
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
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
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.
Sources of Exposure mrem = millirem
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
Gamma or x-ray Beta Alpha Biological Effects of Radiation Effects from external sources depend on penetrating ability.
Parent cell Cell division Normal cells Biological Effects of Radiation
Parent cell Irradiated cell Cell division Cells damaged 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 Biological Effects of Radiation
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
Biological Effects of Radiation • Sources of health hazard data: • Early radiation workers • Medical personnel • Patients treated with radiation • Radiation accident survivors
Units of Measurement • Quantity or concentration of radiation • Absorbed dose (rad) • Dose equivalent man (rem) • Radiation exposure (R)
Roentgen (R) Exposure to x-rays and gamma rays in air is expressed in roentgens (R)
Radiation Adsorbed Dose • rad • Amount of energy released to matter when radiation comes into contact with it • Expressed in rad
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
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
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?
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
Standards and Guidelines OSHA Dose Limits for employees 18 Years and Younger
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
Standards and Guides Universal symbol
Monitoring Instruments • Personal monitoring • Area monitoring • Surface monitoring
Monitoring Instruments • Personal monitoring: • Film badges, rings • Pocket dosimeter
Basic Safety Factors • Keep exposures As Low As Reasonably Achievable (ALARA) • Time • Distance • Shielding
Basic Safety Factors • Time: • Keep exposure times to a minimum • Minimizes dose • ALARA
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
Basic Safety Factors Inverse Square Law I1R12 = I2R22 I1 = initial intensity R1= initial distance R2 = new distance I2 = new intensity
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
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
Basic Safety Factors • Shielding
Basic Safety Factors • Shielding
Nonionizing Radiation • Sun • Lasers
Biological Effects • The eyes are very susceptible to damage from laser light. • Laser emits either: • Infrared (IR) light • Ultraviolet (UV) light
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.