Factors Affecting Patient Radiation Exposure During Prone and Supine Percutaneous Nephrolithotomy

Radiation exposure from fluoroscopy poses risks to patients and surgeons. Percutaneous nephrolithotomy (PCNL) has traditionally required fluoroscopy, however, the use of ultrasound (US) has decreased radiation exposure. US guidance in supine PCNL (S-PCNL) may further reduce radiation exposure. In this study, we investigate patient and operative factors affecting fluoroscopy time (second), total radiation dose (mGy), and effective dose (ED, mSv) in patients undergoing US-guided S-PCNL or prone PCNL (P-PCNL). We performed a retrospective study of patients undergoing US-guided PCNL in prone and supine positions. Patients with multiple access tracts, pre-existing renal access, or fluoroscopic renal access were excluded. Patient demographic and radiologic and operative data were collected, and compared between the two groups. Ninety-nine patients were included: 45 P-PCNL and 54 S-PCNL. There were no significant demographic differences between the two groups. Operative time, access location, tract length, and total radiation dose (mGy) also did not differ. S-PCNL was associated with lower ED (2.92 ± 0.32 mSv vs 5.3 ± 0.7 mSv, p = 0.0014) despite increased fluoroscopy time (86.32 ± 7.7 seconds vs 51.00 ± 5.1 seconds, p = 0.004), and was more likely a mini-PCNL (35.2% vs 15.9%, p = 0.032). In multivariate analysis, S-PCNL remained associated with reduced ED compared with P-PCNL (p = 0.002), whereas body mass index (p < 0.001) and staghorn calculi (p < 0.001) were independently associated with increased ED. We demonstrated that ED in US-guided PCNL is increased in the prone position compared with supine position, and in overweight patients regardless of position. US-guided S-PCNL may decrease radiation exposure to patients and surgeons compared with US-guided P-PCNL.