ALARA Principles: Standard Safety Protocol of Radiation

The most important principle of radiation safety is ALARA. This acronym stands for “As Low As Reasonably Achievable”.

The International Commission on Radiological Protection (ICRP) regulates radiation safety standards to protect against the harmful effects of ionizing radiation. The ALARA principle underpins the ICRP’s 3-tiered System of Radiological Protection:

  • Justification: Any decision that alters the radiation exposure situation should do more good than harm.
  • Optimization of Protection: Doses should be kept as low as reasonably possible, taking into account economic and societal factors.
  • Dose Limitation: Total dose for any individual should not exceed the appropriate limits.

The ALARA principle means avoiding any exposure to ionizing radiation, even small doses, that do not directly benefit you. In practice, you must consider three basic protective measures against radiation, namely, time, distance, and shielding.

3 Major Principles of ALARA for Radiation Protection

  1. Time: Minimize your time exposed to the radiation source, to receive the lowest achievable dose.
  2. Distance: Maximize the distance between yourself and the radiation source, to limit radiation intensity.
  3. Shielding: Use barriers of substances that are impenetrable to specific types of radiation.

This is how to apply ALARA in practice:

1. Time  

  • If you work anywhere near a radioactive source, you must try to minimize the amount of time spent near it.
  • Complete your task as quickly as possible, limiting exposure to the source to the absolute minimum.
  • Avoid lingering in dangerous environments like contaminated zones or airborne radioactivity areas.

2. Distance

  • The amount of radiation exposure is inversely proportional to the square of the distance between you and the source. Therefore, if you double the distance, the radiation dose drops to a quarter.
  • This inverse square law means that even a few extra steps away can reduce your exposure by 70-80%.

3. Shielding

How Can You Protect Yourself from Radiation Exposure?

The ALARA principle assumes there is no minimum safe dose of radiation and no acceptable threshold limit of exposure. If you live or work in a place where there is radiation, it is up to you to follow all guidelines and use appropriate techniques to reduce exposure to ionizing radiation.

1. Good Hygiene

  • Practice good hygiene and housekeeping habits to limit any internal radiation hazards from accidentally ingesting radioactive substances.
  • Food and drink should be eliminated from areas where radioactive materials are used or stored.
  • Wash your hands often and avoid touching your mouth to limit the risk of exposure to internal radiation.

2. Control of Contamination

  • Label all radioactive and potentially radioactive zones and items to prevent the spread of contamination.
  • Prevent contamination using absorbent paper or spill trays.
  • Ensure that contaminated items are disposed of in a suitable, labeled waste container.
  • If accidental contamination occurs, immediately decontaminate the area using appropriate methods to prevent spreading.

3. Airborne Hazards

  • Use ductless fume cupboards and/or laminar flow hoods that are connected to appropriate scrubbers and filters.
  • Avoid any dust, aerosol, or volatile gasses in a radioactive area, to reduce the potential for inhalation of radioactive substances.
  • Use appropriate respiratory equipment or protective devices to prevent inhalation of radioactive substances.

4. Use Proper PPE

  • Wearing suitable personal protective equipment (PPE) such as protective gloves, eyewear, aprons, and collars, reduces the possibility of ingesting or absorbing radioactive materials.
  • No PPE can confer complete protection against high-energy, highly penetrating forms of ionizing radiation.
  • The selection of PPE must take into account anticipated hazards, which may need to be modified due to monitoring and assessing actual working conditions.
  • PPE should include both wearable items and personal barriers. Contact Barrier Technologies for expert advice.

5. Source Barrier

  • The ALARA principle is achieved by using specially engineered controls to contain radioactivity.
  • They can have primary and secondary containers, for added safety.
  • A glove box is made of transparent material with gloves reaching into the box for safe handling. 
  • Other work compartments include hot cells and fume hoods.

6. Decorporation

  • Decorporation refers to the removal of radioactive material from the interior or the surface of the body.
  • It may also involve blocking the uptake of radioactive material by specific tissues or organs.
  • Decorporation can range from simple cleanup to procedures that only physicians should perform.
  • Medical decorporation therapy includes reduction and/or inhibition of absorption from the gastrointestinal tract, isotopic dilution, or the use of diuretics, adsorbents, and chelating agents.

7. Effect Mitigation

  • Effect mitigation attempts to reduce the risk of a single dose, or collective doses over time.
  • Certain chemicals can mop up radiation in the body and reduce the effects of radiation exposure or treatments.
  • Some examples are free-radical scavengers like vitamin E, superoxide dismutase, and agents that reduce oxidative damage.

8. Optimal Technology

  • The maxim is to choose the best technology that is appropriate for the job.
  • For instance, new technology may employ a lower dose or tighter beam, or improved shielding.
  • In some situations, the optimal technology may not use ionizing radiation at all, for example, an ultrasound instead of a mammogram.

9. Limitation of Other Exposures

  • This ALARA principle involves limiting exposures to other non-radioactive agents that could exacerbate any potential risks.
  • Avoid genotoxic or carcinogenic substances that cause the initiation, promotion, or progression of tumors.
  • Avoid teratogenic compounds that can cause fetal and developmental abnormalities.
  • Avoiding substances like tobacco is an example of this principle.


The most effective way of limiting radiation exposure is by always following the ALARA principle. Remember the 3 basic protective measures against radiation, namely, time, distance, and shielding.

The ALARA principle is not just a general guideline for any kind of activity, professional or otherwise, that may involve radiation exposure, but it is an immutable legal requirement. It requires that all reasonable steps be taken to protect people, animals, and the environment.

Barrier Technologies is committed to upholding the ALARA principle by engineering products with superior performance against the harmful effects of ionizing radiation. Call or email us today.