ISSN 2398-2977      

Radiography: radiation safety

pequis

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 biologic 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 gastointestinal 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.
  • Radiation safety governs risk to:
    • Radiographer.
    • Public.
    • Patient.

USA

  • Safety is governed by State and Federal Laws which are based upon the recommendations of The National Council on Radiation Protection and Measurements (NCRP), Report No.116 (1993).

UK

  • Safety is governed byThe Ionising Radiation Regulations 1999 (IRR99).
  • Veterinary Guidance Notes, in line with IRR99, are currently being written.

Souces 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.
    • Use long-handled cassette holders   Radiography: x-ray cassette holder   or x-ray positioner   Radiography: x-ray positioner 
    • Care should be taken that the horizontal beam does not 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 traveling in any direction.
  • Methods of protection:
    • Minimise 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 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.

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 from 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.

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

Other sources of information

  • Health and Safety Executive (2000) Work with Ionising Radiation. In: IRR99 - Approved Code of Practice and Guidance. HSE Publications. ISBN: 0 7176 1746 7.

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