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Written by

Dr Rishi Khanna

Dr Rishi Khanna is a consultant anaesthetist at Bradford Teaching Hospital, UK.

Radiation safety for pain practitioners

Published 21 July 2017

Dr Rishi Khanna discusses the risks associated with exposure to ionising radiation by pain practitioners and the safety measures that should be undertaken

Key learning points

  • Physicians should understand the risks associated with X-rays and other ionising radiation and always use the minimally safe dose where possible.
  • Procedural and organisational safety factors are governed by EU health and safety legislation.
  • Measures minimising exposure eg pulsed screening, beam collimation and avoiding magnification should be followed.

Introduction

Despite the advances in ultrasound technology, the use of ionising radiation in pain procedures remains widespread. It is incumbent on physicians to understand the risk posed by X-rays and comply with all relevant safety aspects. One should always consider using the minimally safe dose when using X-ray imaging.1

Dangers

The primary cause of damage to biological tissue is through transfer of energy, where damage is proportional to the energy involved. The unit used to quantify radiation is the Gray (Gy), which is the transfer of 1 Joule of energy in 1kg of matter.1High energy can cause direct ionisation of biological molecules.

Within interventional pain practice, low energy exposure can result in free radical formation that can damage DNA. The effects of this are seen in cells undergoing more rapid cell division, such as in bone marrow and skin. There may be additional effects on fetal development in pregnant staff and patients. Anecdotally, hair loss and cataracts are often seen in physicians who work with radiation. Chronic exposure can result in cancer including leukaemia, skin, bone or thyroid cancers.1

Safety

There are procedural and organisational factors that should be considered when using ionising radiation, governed by EU legislation on health and safety.

It is important for clinicians to consider radiation exposure during the procedure and the cumulative effect over their working lifetime. For simple pain procedures such as lumbar epidural steroids, the estimated dose is between 6.5-40mGy per patient. Although the physician may be exposed to a small fraction of this, where the procedure is repeated multiple times over a year, the equivalent lifetime cancer risk approximates to one abdominal CT scan a year.1 

Most clinicians will be exposed to radiation through scatter rather than direct exposure of radiation. Placing the image intensifier closer to the patient will reduce scatter. The inverse square law states that the intensity of radiation passing through any area is inversely proportional to the square of the distance from the radiation source. Therefore, stepping away from the X-ray source can reduce exposure to non-protected areas. Obese patients require higher doses of radiation, with more X-ray images needed for extra adjustments in needle position. Lateral, compared to AP, images also demand greater radiation doses, as does continuous screening.

A sound knowledge of anatomy to achieve the treatment goal is paramount.  The use of pulsed rather than continuous screening is encouraged, as is the lowest dose necessary to provide an adequate image. Magnification should be avoided as this increases dose rate. Beam collimation refers to a reduction in beam size and can improve the image quality without increasing the dose.1

Personal protective equipment should be used properly and stored correctly.  This should include 3.5mm lead apron, thyroid shield, and where doses are higher, consider protective eyewear. Healthcare staff should use dosimeters placed under lead aprons to monitor for exposure whilse using fluoroscopy and these should be regularly monitored by healthcare organisations.1


  • Dr Rishi Khanna is a consultant anaesthetist at Bradford Teaching Hospital, UK.

Date of preparation: July 2017; MINT/PAEU-17032