How much does lead shielding during fluoroscopy reduce radiation dose to out-of-field body parts?

Background Fluoroscopy technologists routinely place a lead shield between the x-ray table and the patient's gonads, even if the gonads are not directly in the x-ray field. Internal scatter radiation is the greatest source of radiation to out-of-field body parts, but a shield placed between the patient and the x-ray source will not block internal scatter. Prior nonfluoroscopy research has shown that there is a small reduction in radiation dose when shielding the leakage radiation that penetrates through the collimator shutters. The goal of this in vitro study was to determine if there was any radiation dose reduction when shielding leakage radiation during fluoroscopy. Methods This was an in vitro comparison study of radiation doses using different collimation and shielding strategies during fluoroscopy. Ionization chamber measurements were obtained during fluoroscopy of an acrylic block with and without collimation and shielding. Ionization chamber readings were taken in-field at 0 cm and out-of-field at 7.5, 10, and 12.5 cm from beam center. Results Collimation reduced 87% of the out-of-field radiation dose, and the remaining measurable dose was because of internal scatter. The radiation dose contribution from leakage radiation was negligible, as there was not any measurable radiation dose difference when shielding leakage radiation, with P value of.48. Conclusion These results call into question the clinical utility of routinely shielding out-of-field body parts during fluoroscopy.