Radiation exposure during continuous and pulsed fluoroscopy

Background and Purpose: Previous studies using pulsed fluoroscopy have shown variable effects on radiation exposure because of the ramp and trail effect in older C-arm systems. This study compares radiation delivered in pulsed and continuous modalities using a modern C-arm system. Materials and Methods: Thermoluminescent dosimeters (TLDs) positioned in three body locations directly measured radiation dose during simulated ureteroscopy. Thirty pedal activations were administered using a pulsed or continuous mode to visualize an implanted guidewire and a radiopaque stone. TLD absorbed radiation and image quality were compared between imaging modes. Results: Pulsed fluoroscopy delivered less radiation compared with continuous fluoroscopy at each site: Anterior skin (0.10 vs 0.26 mGy, P<0.001), kidney (0.15 vs 0.40 mGy, P<0.001), and posterior skin (0.92 vs 2.62 mGy, P<0.001). Mean fluoroscopy time differed between continuous and pulsed modes (12.5 vs 3.0 seconds; P<0.001). Fluoroscopy time positively correlated with radiation exposure at all sites: Anterior skin (0.017 mGy/s, R²=0.90), left kidney (0.026 mGy/s, R²=0.96), and posterior skin (0.18 mGy/sec, R²=0.98). When evaluated by blinded urologists, 100% of reviewers felt pulsed images were adequate to identify guidewire position and 90.5% felt pulsed images were adequate for stone localization. Conclusion: Pulsed fluoroscopy reduced fluoroscopy time by 76% and radiation dose by 64% compared with continuous fluoroscopy. Pulsed fluoroscopy images were adequate for most tasks of ureteroscopy and should be considered for reduction of radiation during ureteroscopy.