The 'As Low as Reasonably Achievable' (ALARA) Principle

The ALARA principle is a general principle – though used most for medical staff and patients - to ensure the safety of workers and the public as much as possible, when the risk is well known. Though radiation is needed to carry out certain treatments – radiotherapy is a principle cancer treatment and X – rays one of the principle imaging techniques - the use of radiation involves risk to everyone involved. In fact, everything we do involves risk – every year, around 100 people die choking on ballpoint pens. The risk from all types of harm is impossible to eliminate, but it can be reduced.

For example, the risk from nuclear radiation experienced by workers and patients in the hospitals can be reduced by:

  1. Reducing the time of exposure to nuclear radiation. If the same effect can be achieved with a lower dose of radiation, it is the lower dose that should be administered. Between Exposure incidents, the body's repair mechanisms go to work to reduce the damage caused.

  1. Increasing the distance between you and the radiation source will reduce exposure because the radiation dose received decreases at least as fast as the square of the distance.

  2. Shielding people from sources of radiation. People often do not need to be shielded from alpha and beta sources since these are short range. Exposure to gamma radiation however is increased in the absence of shielding and medical staff in hospitals are often shielded from by lead from gamma ray sources (and X – ray sources too) when these sources are used to treat or take images of patients.

  3. Ensuring that the half life of the radiation is about the same as the length of the treatment. Less long and the treatment migh not be effective. Longer and the total radiation exposure will be increased.

  1. Using other imaging techniques where possible. These include ultrasound (quite cheap), MRI and CAT scans (both expensive). These techniques involve no exposure to nuclear radiation and very little risk (though some people may die falling off the bed).

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