MOD 2 - Radiation Exposure Context

Ionizing Radiation

• higher energy/higher frequency range of the Electromagnetic energy spectrum

  • alpha

  • beta

  • neutron

  • electromagnetic waves

Describe a variety of sources of radiation exposure

• natural → contributes most to total radiation exposure

  • terrestrial (from earth/soil)

    • radioactive materials

      • uranium

      • potassium

      • thorium

  • cosmic (radiation from outer space; closer to source = more exposure → cosmic ray dose increases with altitude )

    • primary cosmic rays interact with atoms and molecules in the atmosphere creating secondary particles:

      • protons

      • electrons

      • neutrons

      • positrons

  • gamma rays (natural and man-made)

    • produced by

      • decay of radioactive atom

      • high-energy voltages of lightning

      • high-energy cosmic rays hitting Earth

      • radon gas

  • human body and bananas

    • potassium-40 is an important radionuclide found in human bodies

  • radon and thoron

    • gas released from the decay of Uranium and thorium

    • radon gas is constantly emanating from the ground

    • radon-222 is not too dangerous as we breathe it in and breathe it out

    • however the decay products of radon-222, bismuth and polonium are heavy metals that attach to dust particles and tend to accumulate in the lung → lung cancer

• man-made

  • nuclear (events/incidents)

    • Chernobyl

    • Fukushima

    • Hiroshima

  • medical

    • CT

    • Nuclear Medicine

    • Fluoroscopy

  • industrial sources

    • uranium mining production

    • nuclear power plants

    • smoke detectors

Explain the current classification of radiation exposure

• occupational = work/job

• medical = exams for care and diagnosis

• public/background = where you live, lifestyle (highest source of radiation)

Describe the categories of biologic effects related to radiation exposure

• ionizing radiation + living system = cellular ionization

• LET = linear energy transfer, a measure of how much energy an ionizing particle transfers to a material

  • x-rays and gamma rays are low-LET radiation

  • lower LET = few interactions with cellular DNA and thus lower chance of damage to genetic material

• dose magnitude = source of radiation

• whole or partial body = whole body exposure → more significant

• individual characteristics

  • age (older means lower chance of effects showing bc you can only live a bit more)

  • gender (women are more radiosensitive),

  • BMI (small/thin = more likely for radiation to interact)

• early effects (within hours to months after exposure)

  • large whole body dose

  • nuclear events

  • acute radiation sickness

  • somatic = effects that occur in the exposed individual

  • deterministic = effects that are directly related to the amount of radiation absorbed

• late effects (within years or not at all)

  • carcinogenesis

  • late tissue reactions (cataract)

  • birth defects

Define units of exposure

• grays (gy) = for intensity/measurement of ionizing radiation

• sieverts = potential damage/risks to biological tissue caused by exposure