Radiation exposure during 3D fluoroscopy of the knee: an experimental study.

PURPOSE: To measure the radiation exposure at the knee and surrounding area during the use of 3D fluoroscopy.

METHODS: An experimental study was conducted by using a human cadaveric knee as a focus point for the 3D fluoroscope. An isocentric C-arm fluoroscope machine was applied on the lateral side of the knee. The radiation dosage at the focus point and surrounding area was measured. The mean radiation exposure in each location was compared between low- and high-resolution scanning.

RESULTS: The mean radiation sustained at the focus point was 44.0 ± 5.6 μSv and 20.0 ± 1.0 μSv in high- and low-resolution scanning, respectively. Radiation exposure on the opposite side of the C-arm machine was found to be higher than that on the other locations with the same distance from the focus point. In low-resolution scanning, radiation could not be detected beyond 75 cm from the focus point at the proximal, distal and same side of the machine. Radiation could be measured at a distance of up to 1.25 m on the opposite side of the machine. In high-resolution scanning, radiation could be measured at a distance of up to 1 m at the proximal, distal and same side of the C-arm, but up to 1.5 m on the opposite side.

CONCLUSION: Radiation exposure during 3D fluoroscopy of the knee decreases with increasing distance from the focus point. A higher number of scans in the high-resolution mode causes greater radiation exposure. In isocentric 3D fluoroscopy of the knee, a safe zone is located at least 1.5 m away from the focus point.