Lapis ISSN 2398-2969

Radiography: radiation safety

Contributor(s): Vetstream Ltd, David Vella

Introduction

  • It is essential to follow rigid safety guidelines when dealing with radiation which:
    • Is invisible.
    • Is painless.
    • Has cumulative effects.
    • Has latent effects which may manifest at a later time.
    • X-rays pose a safety hazard due to their biological effects on tissue.

Effects of ionizing radiation

  • Somatic effects- the direct effect seen on tissue immediately after exposure to a high dose (dose dependent) of radiation.
  • Rapidly dividing cells are most sensitive and signs reflect body system affected, eg skin reddening or gastrointestinal disturbance. 
  • Carcinogenic effect- tumors may be induced decades after the radiation exposure. 
  • Genetic effects- mutations occurring in the chromosomes of germ cells in the ovaries or testes may cause effects in the offspring. 
  • Safety is governed byThe Ionizing Radiation Regulations 1999 (IRR99)
  • Radiation safety governs risk to: 
    • Radiographer. 
    • Public. 
    • Patient.

Sources of radiation

  • The radiographer may be exposed to radiation from a number of sources during exposure.

The primary beam

  • Contains high energy radiation.
  • Methods of protection: 
    • Collimate the beam tightly to the area of interest. 
    • The light beam diaphragm should show the area of the primary beam but this must be checked regularly to ensure it is accurate. 
    • Avoid manual restraint but if essential stand as far from the primary beam as possible. 
    • Avoid horizontal beam radiography if possible, since the primary beam is harder to define and may pass through walls or windows.

NEVER allow any part of the radiographer to be within the primary beam.

Scattered radiation

  • Lower energy radiation. 
  • Produced when primary beam is incident on an object. 
  • May be travelling in any direction.
  • Methods of protection: 
    • Minimize scatter production.
    • Radiographer should stand as far away from patient as possible (a long exposure cable permits this). 
    • Wear protective lead clothing, eg gloves and gowns. 
    • Reduce number of radiographic examinations to a minimum.
  • The tube head:
    • Cracks in the lead lining may allow radiation escape in any direction.
  • Methods of protection
    • Check integrity of lead shield regularly by taping x-ray film in envelope to tube head, making a few exposures and then exposing film (presence of blackened areas of film indicates radiation leakage). 
    • Radiographer should stand as far from the tube head as possible.

The x-ray room

  • In most practices a room is designated as the x-ray room.
  • This room should be self-contained and have brick walls.
  • Ideally personnel in the room should be able to stand more than 2 m from the tube head during exposure.
  • If this is not possible a lead screen should be placed within the room.
  • Special considerations should be made if there is a room beneath the designated room!

Controlled area

  • The area around the primary beam where the average dose rate of exposure exceeds a limit set by regulations.
  • Defined by Radiation Protection advisor (RPA).
  • Usually 2 m radius from primary beam.
  • Controlled area must be demarcated and defined so practically easier to define x-ray room as controlled area.
  • If the x-ray machine is disconnected form its power source the room reverts to a normal room.
  • Warnings must be visible outside the controlled area in the form of lights or notices which are only displayed when the x-ray machine is in use.
  • Radiography should be performed on a lead covered table to:
    • Prevent penetration of the primary beam through the table. 
    • To absorb scattered radiation.

The x-ray table must be at least as big as the area of the primary beam.

Protective clothing

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Patient restraint

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Dosimetry

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Radiation legislation

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Further Reading

Publications

Refereed papers
  • Recent references fromPubMedpublished during the last 12 months.

Other sources of information


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