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Study Notes: Basics of Radiation Safety

Radiation can and will cause damage to the human body. For instance, atomic weapons used in warfare cause horrific radiation damage to the survivors of the explosion. We now know that too many X-rays can be a health risk and limit their availability to medically required testing.

Radiation hazards can be external, for instance being exposed to a beam of α, β or γ radiation or internal, for instance ingestion of a radionuclide.

External Radiation Hazards
Can be controlled by three basic methods:

  1. Shielding or blocking the path of the radiation with some substance.

    Radiation
    Shielded by
    Comments
    Alpha - α A thin sheet of paper. Alpha particles are easily absorbed.
    Beta - β 10 mm sheet of Perspex or aluminium. High mass number metals such as lead should not be used to shield beta radiation as dangerous X-ray radiation is produced as a consequence.
    Gamma - γ Lead – up to 6 cm or more. Dependent of energy of the gamma radiation.

    Shielding includes the use of protective equipment such as lead aprons, gloves, face masks, lead bricks, lead-glass blocks etc.

  2. Time - reduce exposure time to reduce overall exposure. Often used by workers in the radiation industry to limit their dose as:

    Dose = dose rate x time

  3. Distance – doubling the distance from the radiation source reduces the dose of radiation by ¼ according to the inverse square law:

    Dose = 1/Distance2

    External Radiation Hazards are often monitored by wearing a personal radiation film badge or a dosimeter. The device is checked regularly and any excessive exposure leads to:

    • investigation of the source of the exposure
    • re-training if necessary
    • cessation of duties for a prescribed time.

Internal Radiation Hazards
Ingestion of a radionuclide via inhalation, ingestion, skin, wounds or direct irradiation of the skin.

The common methods to reduce ingestion include:

  • proper training
  • correct PPE
  • personal hygiene, including handwashing
  • written SOPs for handling and storage
  • clean up procedures
  • environmental monitoring
  • written emergency and clean up procedures.

Find out more information on radiation safety by going to the Resources and Training Room and choose the ANSTO's web site from the World Wide Web Catalogue.

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