Introduction to Radiation Protection

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Introduction to Radiation Protection
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Effective Radiation Protection

• Radiation protection can be defined as effective
  measures employed by radiation workers to
  safeguard patients, personnel, and the general
  public from unnecessary exposure of ionizing
  radiation.
• That is why facilities should establish a
  radiation safety program.
• It is important to ensure radiation safety during
  all medical radiation procedure.

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Biologic Effects

• The need for safety against significant and
  continuing radiation exposure is based on
  evidence of harmful biologic effects.
• This can be applied to the radiation worker,
  patient, or to the general public.
• This biological effects depend on the radiation
  exposure or dose. Generally, exposure to these
  kinds of radiation would be very harmful to human
  beings. The effects could be either short-term or
  long-term.

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Benefits Vs. Risk

• Radiation exposure should always be kept as low
  as possible.
• But, when illness and injury occurs or when a
  specific imaging procedure for health screening
  purposes is important, the patient can choose to
  assume the risk of the exposure to radiation to
  obtain an essential medical information.

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Diagnostic Efficacy

• Diagnostic efficacy is the degree to which the
  diagnostic study accurately reveals the presence
  or absence of a disease in the patient.
• Efficacy is a vital part of radiation protection
  in the healing arts.
• It provides the foundation for determining
  whether an imaging procedure or practice is
  acceptable.

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Achievement of Diagnostic Efficacy

• It is important for the referring physician to
  carry the responsibilities for determining the
  medical necessity for the patient.
• After ordering an x-ray examination or procedure,
  the physician must accept basic responsibility to
  protect the patient from non-useful radiation
  exposure.
• Its is also the radiographers responsibility for
  the patients well-being by providing quality
  imaging services.

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• Both the radiographer and the radiologist share
  in keeping the patient medical radiation exposure
  at the lowest level possible.
• This way imaging professionals help ensure that
  both occupational and nonoccupational dose
  limits, that result in a negligible risk of
  bodily injury or genetic damage, will remain in
  well below maximum allowable.

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ALARA

• ALARA is an acronym for As Low As Reasonably
  Achievable.
• The reason for this concept in radiologic
  practice is to keep radiation exposure and
  consequent dose to the lowest possible level.
• For the radiographer and the radiologist the
  ALARA concept should serve as a guide for the
  selection of technical radiographic and
  fluoroscopic exposure factors for all patient
  imaging procedure.

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Responsibility for Maintaining ALARA

• It is the responsibility of the employer to
  provide the necessary resources and appropriate
  environment in which to execute an ALARA program.
• To determine that proper lowered radiation
  exposure are being applied, management should
  perform periodic exposure audits.
• Radiation workers with appropriate education and
  work experience must function with awareness of
  rules governing the work situations.

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Patient Protection and Patient Education

• Patients should always be aware of what type of
  procedures are being done, and what kind of
  cooperation is needed, but also they need to be
  informed from the radiologist of what is being
  done.
• Through appropriate and effective communication,
  patients can be made to feel that they are active
  participants in their own health care.

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Background Equivalent Radiation Time (BERT)

• This method compares the amount of radiation
  received.
• Radiographers can use this method to understand
  and reduce the fear and anxiety of the patient.

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Types of Radiation

• Radiation is defined as energy in transit from
  one location to another.
• Radio waves, ,microwaves, visible light, and
  x-rays represent electromagnetic waves.
• Electromagnetic waves are characterized by their
  wavelength.

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Types of Radiation

• The full range of frequencies and wavelengths of
  electromagnetic waves is known as Electromagnetic
  Spectrum.
• Each frequency and within the spectrum has a
  characteristic wavelength and energy.
• Electromagnetic spectrum can be divided into two
  parts ionizing and nonionizing

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Ionizing and Nonionizing

• Only X-ray and gamma radiation are known as
  ionizing radiation.
• Ultraviolet, visible light, infrared rays,
  microwaves, and radio waves are considered to be
  nonionizing radiation, because they do not have
  sufficient kinetic energy to eject electrons from
  the atom.

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Ionizing and Nonionizing

• Ionization is the foundation of the interactions
  of x-rays with human tissue.
• The amount of energy transferred to the electrons
  by ionizing radiation is the basis of the concept
  of radiation dose.

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Particulate Radiation

• This radiation includes alpha particles, beta
  particles, neutrons, and protons.
• These subatomic particles are ejected from atoms
  at very high speeds.
• Particulate radiations vary in their ability to
  penetrate matter.

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• EQUIVALENT DOSE AND EFFECTIVE DOSE
• Equivalent Dose (EqD) A quantity that attempts
  to take into account the variation in biologic
  harm that is produced by different types of
  radiation.
• Equivalent Dose (Eqd) enables the calculation of
  the Effective Dose (EfD)
• Effective Dose (EfD) A quantity that attempts
  to summarize the overall potential for biologic
  damage to a human due to exposure to ionizing
  radiation.
• Effective dose takes into account organ
  weighting factors and represents the whole body
  dose that would give an equivalent biologic
  response.
• EfD and EqD are both expressed in sieverts (Sv),
  used by the International System of Units (SI),
  or rem, which adopts the traditional measuring
  system

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• SOURCES OF RADIATION
• Human beings are continuously exposed to sources
  of ionizing radiation
• Ionizing radiation from environmental sources is
  called natural background radiation.
• There are three types of natural background
  radiation
• Terrestrial Radiation
• Cosmic Radiation
• Internal Radiation

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• TERRESTRIAL RADIATION
• Long-lived radioactive elements such as
  uranium-238, radium-226, and thorium-232 that
  emit ionizing radiations are present in variable
  quantities in the earths crust.
• These elements are found in rocks, soil, the
  water we drink, the food we eat, and building
  materials.
• Approximately 55 of the gross common exposure of
  human beings to natural background radiation
  comes from radon, contributing approximately
  198mrem per year to the average American.

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• Cosmic Radiation
• Cosmic rays are of extraterrestrial origin and
  result from nuclear interactions that have taken
  place in the sun and other stars.
• Cosmic radiations consist predominantly of
  high-energy protons
• The greatest intensity occurs at high altitudes,
  and the lowest intensity occurs at sea level.
• The average U.S. inhabitant receives an average
  of 30mrem per year of extraterrestrial radiation.

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• INTERNAL RADIATION
• The tissue of the body contain many naturally
  existing radionuclides that have been ingested in
  minute quantities from various foods or inhaled
  as particles in the air.
• A radionuclide is an unstable nucleus that emits
  one or more forms of ionizing radiation to
  achieve greater stability.
• Examples of internal radionuclides are
  Potassium- 40, Carbon-14, Hydrogen-3 (Tritium),
  and Strontium-90
• An average individual receives
• approximately 67mrem per year from
• combined exposure to radiations
• from the earths surface and radiation
• within the human body.

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• MANMADE (ARTIFICIAL) RADIATION
• Ionizing Radiation created by humans for various
  uses is classified as manmade, or artificial,
  radiation.
• Sources of artificial ionizing radiation include
• Consumer products containing radioactive material
  (ie. airport surveillance systems)
• Air Travel (brings humans in closer contact to
  extraterrestrial radiation and sunspot activity)
• Nuclear fuel for generation of power (does not
  contribute much to annual equivalent dose of the
  U.S. Population)
• Atmospheric fallout from nuclear weapons (also
  has a negligible impact on the U.S. population
• Nuclear power plant accidents (ie. Three Mile
  Island and Chernobyl)
• Medical Radiation (ie. Diagnostic medical x-ray
  and nuclear medicine procedures)
• Manmade radiation contributes about 65mrem to the
  average annual radiation exposure of the U.S.
  population.

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Dose Limits for Exposure to Ionizing Radiation
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Basis of Effective Dose Limiting System

• The concept of radiation exposure and associated
  risk of radiation-induced malignancy, is the
  basis of the effective dose limiting system.

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Radiation Protection Standards

• Future radiation protection standards are
  expected to continue to be based on risk.

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Radiation Protection Guidelines

• Because medical imaging professionals share the
  responsibility for patient safety from radiation
  exposure in the performance of their duties, they
  must be familiar with previous, existing and new
  guidelines.

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Major Organizations Involved in Regulating
Radiation Exposure

• The UNSCEAR and the NAS/NRC-BEIR supply
  information to the ICRP.
• The International Commission on Radiological
  Protection (ICRP) makes recommendations on
  occupational and public dose limits.

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National Council on Radiation Protection and
Measurements

• The NCRP reviews ICRP recommendations and
  implements them into U.S. radiation protection
  policy.

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The Nuclear Regulatory Commission

• The NRC is the watchdog of the nuclear energy
  industry it controls the manufacture and use of
  radioactive substances.

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Environmental Protection Agency

• The EPA develops and enforces regulations
  pertaining to the control of environmental
  radiation.

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Food and Drug Administration

• The FDA regulates the design and manufacture of
  products used in the radiation industry.

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Occupational Safety and Health Administration

• The U.S. Occupational Safety and Health
  Administration (OSHA) functions as a monitoring
  agency in places of employment, predominantly in
  industry.
• OSHA regulates occupational exposure to radiation
  through Title 29 of Part 10 of the U.S. Code of
  Federal Regulations (29 CFR 1910).

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Radiation Safety Committee and Radiation Safety
Officer

• Radiation Safety Committee (RSC)
• They established the facility to assist in the
  development of radiation safety program
• The radiation safety program ensure adequate
  safety of patient and radiation workers.

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• Radiation Safety Officer (RSO)
• Normally a medical physicist, radiologist, or
  other individual qualified training and
  experience.
• The RSO is responsible for developing a radiation
  safety program for the facility to ensure that
  all persons are protected from radiation.

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The Effective Dose Limiting System (EfD)

• EfD limiting system is the current method for
  assessing radiation exposure and associated risk
  of biologic damage to radiation workers and the
  general public.
• EfD concerns the upper boundary dose of ionizing
  radiation that results in a risk of body injury
  or genetic damage.
• Expressed of whole body exposure, partial body
  exposure, and exposure of individual organs.

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• The RSO is also is responsible for maintaining
  radiation monitoring records for all personnel
• Providing counseling for individuals who receive
  monitor reading in excess of allowable limits.
• The RSO also have to authority to stop exam that
  he or she considers unsafe to personnel or
  patient.

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• The effective dose limits are established to
  minimize the risk to human in terms of
  non-stochastic and stochastic effects.

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Non-Stochastic Effects

• Are biologic somatic effects of ionizing
  radiation that can be directly related to the
  dose received.
• The effect exhibits a threshold dose below which
  the effects does not normally occur
• Which the biologic damage increases as the dose
  increases.

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Early and Late Non-Stochastic Effects

• Early Non-Stochastic
• Few hours or days after a very high level
  radiation exposure to the body
• Redness on the skin (erythema)
• Decrease in white blood cell count.
• Loss of hair (epilation)

• Late Non-Stochastic
• Occurs in months or years after high level
  radiation exposure .
• Cataracts
• Organ atrophy
• Reduced fertility
• Sterility caused by a decease in reproductive
  cells

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The ALARA Concept

• In 1954 the National Committee on Radiation
  Protection put the principle that radiation
  exposure should be kept
• As Low As Reasonably Achievable ALARA
• The medical radiographers and radiologist share
  the responsibility to keep occupational and
  non-occupational dose limits as low as possible.

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• The ALARA concepts presents an extremely
  conservative model with the respect to
  relationship between ionizing radiation and
  potential risk.

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Radiation Protection

• Prevention any nonstochastic (deterministic)
  effects by keeping dose limits below threshold
  levels
• Limiting risk of stochastic response to
  conservative levels according to environment
  importance

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Risk

• Risk- probability of injury, ailment, or death
  resulting from an activity
• Risk in medical imaging industry is possibility
  of inducing a radiogenic cancer or genetic defect
  after irradiation
• Occupational risk associated with radiation
  exposure may be equated with risk in other
  industries that are generally considered
  reasonably safe
• Risk of embryo-fetus to radiation exposure due to
  there high sensitivity to radiation can cause
  major defects

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Effective Dose Limiting System

• EfD is an attempt to equate the various risk of
  cancer and genetic effects to tissues or organs
  that are exposed to radiation
• Equivalent dose- determination dose for all
  radiation-vulnerable human organs that contribute
  to potential risk
• Tissue weighting factor indicates the ratio of
  risk of stochastic effects attributable to
  irradiation of given organ or tissue to total
  risk when the whole body is uniformly irradiated

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NCRP Recommendations

• Annual occupational effective dose limits should
  not exceed 50mSv (5 rem) for whole body dose
• Cumulative effective dose limits refers to
  lifetime effective dose age in years multiplied
  by 10mSv for whole body dose
• Collective effective dose in description with
  population or group exposure using an averaging
  the effective dose

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NCRP Recommendations (cont)

• Limits of nonoccupationally exposed individuals
  are set at 1mSv annually for medical exposure and
  5mSv for natural exposure
• Limits for pregnant female radiation workers are
  0.5mSv per month and entire pregnancy dose limit
  of 5mSv
• Limits for education and training purpose for
  individuals under 18years of age is 1mSv annually
• Negligible individual dose is 0.01mSv
• Limits for tissue and organs are set differently
  depending on sensitivity of the organ or tissue.
  
• Lens of the eye 150mSv(15rem)
• Localized skin 500mSv(50rem)

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Occupational Dose Limits

• Action limits are set by health care facilities
  to ensure radiographers do not reach a dose limit
  that can be harmful
• Effective dose limits for radiation workers are
  50mSv (5 rem) annually
• Special limits are set for highly sensitive areas
  of the body such as the lens of the eye and
  localized areas of the skin, hands, and feet to
  prevent nonstochastic effects

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Questions

• T or F/ Radiation exposure should be kept as low
  as possible.
• True
• It is important for the referring physician to
  carry the responsibilities for determining the
  medical necessity for the patient.
• True

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• QUESTIONS
• True or False. EfD enables the calculation of
  EqD.
• False (EqD enables the calculation of EfD)
• The quantity of _______________ radiation
  present in any area depends on the composition of
  the soil or rocks in that geographic area.
• TERRESTRIAL

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• QUESTIONS CONT.
• True or False. To reduce exposure for pregnant
  female radiation workers and to control exposure
  of the unborn during potentially sensitive
  periods of gestation, the NCRP now recommends a
  monthly EqD limit to the embryo-fetus not to
  exceed 0.5mSv (0.05rem) and a limit during the
  entire pregnancy not to exceed 5.0mSv (0.50rem)
  after declaration of pregnancy.
• TRUE
• Radiation hormesis is the hypotheses that a
  positive effect exists for certain populations
  that are continuously exposed to moderate levels
  of radiation.
• TRUE

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Questions

• The radiation safety program ensure adequate
  safety of patient and radiation workers.
• True