Radiation exposure in prone vs. modified supine position during percutaneous nephrolithotomy: Results with an anthropomorphic model

Introduction: Radiation exposure during urologic procedures is still of concern in the urologist’s community. It has been reported that percutaneous nephrolithotomy (PCNL) in supine position will have less irradiation as the puncture is mostly done under ultrasound guidance. However, it can also be done under fluoroscopy guidance. Unfortunately, data on radiation exposure during PCNL is more lacking since they are often drawn form generalization and extrapolation, or not evaluating new procedures or different positions. The aim of our study was to compare the radiation dose depending on the position of the surgeon. Methods: A portable C-arm was used in standard mode (32 impulsions/second; 98kV, 3.8mA). Specific dosimeters were placed for lens, extremity and torso. Anthropomorphic models and hand phantom models were used to reproduce the position of surgeon and patient (with same bone density than human) during PCNL in prone and modified supine position. Fluoroscopy time (FT) was 6 minutes to obtain higher exploitable signal, and the results are given for a FT of 3 minutes (more realistic). Ten percent of the FT is done with an angulation of 15 degrees and the rest in anteroposterior position. Results: The equivalent doses (ED) are given in uSV (uncertainty k=2). During the modified supine position: neck, lens, right index finger, left thumb and index finger received ED of 99 (20%), 62 (18%), 437 (10%), 112 (12%), 204 (10%), respectively. In a prone position, the phantom received ED on the neck, lens, right thumb and index finger, left thumb and index finger of 85 (20%), 92 (12%), 401 (10%), 585 (10%), 295 (10%), 567 (10%), respectively. In both position, the right hand seems more exposed than the left hand. Conclusion: The effective dose is 1.5 and 1.3 fold higher for lens and extremities, respectively, in a prone position PCNL compared to a modified supine position. Both positioning are still well below the recommended limit for professional exposition.