How can anesthesiologists protect themselves from radiation exposure
Most institutions abide by the ALARA philosophy when it comes to protecting their workers: radiation exposure should be kept As Low As Reasonably Achievable. There are three basic strategies to the ALARA philosophy:
■ Maximize the distance to the source: Newton's inverse square law, which applies to any point source that spreads its influence in all directions (such as light, sound, gravitational field) tells us that the intensity of the radiation at a given radius is the source strength divided by the sphere area. Or, put more plainly, the intensity (I) of radiation is inversely related to the square of distance (d) from the source:
Thus increasing the distance from an x-ray machine or a fluoroscope when in use can profoundly affect the intensity of radiation exposure. Six feet of air provides the equivalent protection of 9 inches of concrete or 2.5 mm of lead.
- Minimize the time of exposure: Most medical occupational radiation exposure comes from x-rays scattered by both the patient and surrounding equipment. Obviously this scatter occurs only when the machine is on. A person's radiation exposure is directly proportional to the length of exposure; thus every reasonable effort to limit the time of exposure is beneficial.
- Use shields: Most aprons contain the equivalent of 0.25 to 0.5 mm of lead, which is effective at blocking most scattered radiation in medical settings. Uncovered areas such as the lens of the eye still run the risk of radiation exposure. Other shields such as concrete walls and portable barriers should be used whenever possible. Lead aprons should be x-rayed periodically to determine if they are still effective barriers because they are known to deteriorate with lime particularly if mishandled.
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