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AAOS Now

Published 3/1/2015
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Jennie McKee

Measuring Radiation Exposure from Fluoroscopy

Certain intraoperative fluoroscopy views may expose orthopaedic surgeons to a greater degree of radiation than other views, according to a study presented at the 2014 annual meeting of the Society of Military Orthopaedic Surgeons (SOMOS).

Research presented by LCDR Michael Kuhne, MD, suggests that lateral views of the lumbar spine, hip, and thoracic spine expose the surgical team to the most radiation. Orthopaedists should be aware of this greater amount of radiation exposure, he said, given the increasing use of intraoperative fluoroscopy to assess implant placement and fracture alignment.

“The cumulative effects of low-dose radiation are unknown,” said Dr. Kuhne. The International Commission on Radiological Protection (ICRP) recommends that occupational radiation exposure be limited to 20 milliSieverts (mSv) per year; long-term radiation exposure has been linked to hereditary disorders and carcinogenesis.

Based on the study’s results, Dr. Kuhne urged orthopaedists and other members of the surgical team to take any possible precautions against radiation exposure, such as stepping away when taking images, if possible.

Studying radiation exposure
Using four full-body, fresh-frozen cadavers and a 9-inch C-arm, investigators created 37 standardized fluoroscopic images common in orthopaedic trauma cases.

The investigators placed four real-time dosimetry badges on two towers that simulated the surgeon and first assistant.

“The towers were placed one foot from the operating table to eliminate the variable of distance,” explained Dr. Kuhne. “And, as in surgery, the tower representing the surgeon was placed on the side of the table opposite the C-arm. The tower for the assistant was placed on the same side as the C-arm.”

During upper extremity imaging, said Dr. Kuhne, both towers were on the side opposite the C-arm. Radiation exposure from one minute of continuous fluoroscopy was recorded in microSieverts (µSv) for each view. For each image, the two dosimeters for the surgeons and the two dosimeters for the assistant were averaged.

Analyzing the results
The greatest average radiation exposure to the surgeon—measured at 124 µSv, 114 µSv, and 88 µSv per minute—came from the lumbar spine lateral view, the hip lateral view, and the thoracic spine lateral view, respectively. The average exposure to the assistant was much lower, at 7 µSv, 28 µSv, and 9 µSv per minute for each of those images.

The least radiation received was during distal radius imaging (1.56 µSv per minute).

Based on the study results, it would take 12,800 minutes of fluoroscopic imaging of the distal radius view to reach the ICRP’s recommended maximum amount of occupational radiation exposure per year, but only 160 minutes of lateral lumbar fluoroscopy.

“There’s high exposure to the surgeon in a hip lateral position, which is commonly used in femoral nailing,” said Dr. Kuhne.

The study had several limitations, including that all cadavers remained in the supine position and that the lowest detectable limit of the dosimeters was 1 µSv.

Minimizing risk
“These data show the amount of radiation exposure received by the surgeon for each fluoroscopic image,” said Dr. Kuhne. “This information enables us to minimize radiation risks during orthopaedic trauma cases by increasing awareness of images associated with higher exposure.”

Previous studies have shown that radiation exposure from fluoroscopy can be decreased, noted Dr. Kuhne.

“When possible, surgeons should consider taking a step away when taking images because radiation decreases with the square of the distance,” he said. Placing the patient closer to the image intensifier or the receiving end of the fluoroscopy machine also decreases exposure.

Other ways to limit radiation exposure risk include “decreasing total fluoroscopy time, avoiding metal objects and large amounts of tissue for the X-rays to penetrate, not placing your body directly in the X-ray beam, collimating the beam to expose only the location of interest, and avoiding magnification,” he added.

Dr. Kuhne’s coauthors of “Determination of Radiation Exposure from Intraoperative Fluoroscopy Views in Orthopaedic Trauma” include Mr. Kiley Libuit and Meir T. Marmor, MD.

The authors’ disclosure information, including potential conflicts of interest, can be viewed at http://www.aaos.org/disclosure

Jennie McKee is a senior science writer for AAOS Now. She can be reached at mckee@aaos.org

Bottom Line

  • Intraoperative fluoroscopy used to assess implant placement and fracture alignment exposes surgeons and other members of the surgical team to radiation.
  • The surgeon’s exposure to radiation varies greatly depending on the type of fluoroscopic view, with the greatest average exposure occurring during lateral views of the lumbar spine, hip, and thoracic spine.
  • To minimize risk of radiation exposure, step away when taking images, decrease fluoroscopy time, and place the patient closer to the receiving end of the fluoroscope.