Laser targeting with C-arm fluoroscopy: effect on image acquisition and radiation exposure

Reducing unnecessary radiation exposure from medical imaging is paramount. This study assessed whether a laser aiming guide for C-arm fluoroscopy reduced the number of exposures needed to obtain an acceptable image, thereby reducing total fluoroscopy time for hip, knee, and ankle fluoroscopy.

An obese cadaver was placed supine on a radiolucent surgical table. Images were obtained by licensed radiologic technologists using a calibrated OEC 9900 Elite C-arm with laser targeting (LT) and without LT (NLT). Dosimeters were placed 1, 3, and 6 ft (30.5, 91.5, and 183 cm) away from the center of the C-arm at 90-degree angles at 2 levels, simulating thyroid and gonadal exposure. Posterior-anterior (PA) images of the bilateral lower extremities were obtained with each technician acquiring 24 centered images (hip, knee, and ankle) using both LT and NLT C-arm fluoroscopy.

Total fluoroscopy time was reduced by 19% when using LT with a 39% reduction for the knee and a 29% reduction for the ankle. The addition of LT improved the likelihood of obtaining a centered image for knees and ankles but not for hips. The gonadal dosimetry data were significantly higher than the thyroid dosimetry badges at 1 ft. At the 3-ft zone, only trace amounts of radiation were detected; the 6-ft zone reported no radiation exposure in either group.

LT helped with imaging knees and ankles with statistically significant reductions in fluoroscopy time and a statistically significant improvement of image quality defined as obtaining a centered PA image faster. The dosimetry badges detected minimal exposure at 3 ft and no detectable exposure at 6 ft at both levels.