Occupational Exposure: Radiation

Anesthesiologists are exposed to radiation intraoperatively through the increasing use of x-rays, fluoroscopy, and computed tomography (CT) scanning. Exposure depends on the amount of time exposed for, total radiation intensity and the distance from radiation source. Radiation intensity is inversely related to the distance squared. As distance from the source increases, radiation intensity decreases (represented at 1/d^2, where d is distance).

Ionizing radiation generates free radicals and ionized molecules by driving electrons out of their stable orbitals. This results in tissue damage and chromosomal changes leading to malignancies. Ionizing radiation exposure is measured by units of absorbed doses (gray or rads) or equivalent dose units such as Sievert (Sv) and Roentgen equivalent in man (rem). The unit rem is a measure of biologic damage from radiation adjusted to apply to all tissues and is commonly used for radiation monitoring. Radiation levels of hospital employees are monitored, often by film badges, and total exposure is tracked to avoid exceeding 5 rem/yr.

With evolving imaging techniques and more frequent utilization in the OR, radiation exposure is becoming more common for anesthesiologists. Occupational exposure occurs primarily from x-rays scattered by the patient and surrounding equipment. In an effort to help protect themselves, anesthesiologists operate around the basic tenet of radiation exposure which is “as low as reasonably practical” (ALARP) or “as low as reasonably achievable” (ALARA). Organs such as the eyes (radiation-induced cataracts are increasing among employees in interventional radiology suites as protective eyewear was not consistently used in the past), thyroid, and reproductive organs must be protecting as well as blood and bone marrow. Special attention should be paid to pregnant women, particularly in their first trimester, and their exposure to be limited to a maximum of 500 mrem.

Ways to mitigate radiation exposure include:

1) Minimizing exposure time, which can be difficult sometimes in long fluoroscopic operations

2) Maximizing distance from radiation source: radiation exposure follows inverse square of distance (1/d²).

3) Shielding, which includes wearable protections such as leaded aprons and glasses as well as physical shields like walls or mobile leaded shields that can be placed between providers and the radiation source.