Introduction: Flat-Panel Detector C-arms (FPDs) are reported to reduce radiation exposure and improve image quality compared to conventional image intensifier C-arms. Because FPDs employ proprietary designs, radiation doses and image quality may differ between manufacturers. The purpose of this study was to compare radiation exposure and image quality between three FPD manufacturers.
Methods: A male cadaver (BMI=33.4) was placed prone on an operating table to simulate percutaneous nephrolithotomy (PCNL). For each trial, three optically stimulated luminescence dosimeters (OSLDs) were placed on the cadaver skin: one ventrally overlying the renal pelvis and two dorsally overlying the upper and lower kidney poles. FPDs from three manufacturers (GE, Philips, and Ziehm) were positioned to maintain 35.5 cm between the source and the bottom of the operating table. For each FPD, five trials were conducted under three different conditions: automatic exposure control (AEC), AEC with low-dose (LD), and low-dose with lowest pulse rate (LDLP). Each trial applied 300 seconds of radiation. Radiation doses were measured using a Landauer microStar OSLD reader. 10 blinded urologists (5 attendings and 5 residents) completed a survey of image quality. Results were analyzed using ANOVA and Tukey’s B post-hoc analysis.
Results: At the AEC setting, the Philips C-arm produced significantly less exposure to the ventral OSLD than both GE and Ziehm (42,446 vs. 51,076 vs. 83,178 mrad, p<0.001, respectively). Similarly, at the LD setting, the Philips C-arm produced significantly less exposure to the ventral OSLD than both GE and Ziehm (25,926 vs. 30,956 vs. 38,209 mrad, p<0.001, respectively). At the LDLP setting, the Ziehm C-arm produced significantly less exposure to the ventral OSLD than both GE and Philips (4,019 vs. 7,418 vs. 8,229 mrad, p<0.001, respectively). Under all three conditions, dorsal OSLD exposures paralleled ventral exposures. At all three settings, the GE C-arm had the highest image quality, but image quality was rated adequate for clinical procedures at AEC and LD settings in all three manufacturers. At LDLP, the Ziehm C-arm was rated inadequate in 8% of images, compared to 0% of GE and 0% of Philips (p=0.016).
Conclusions: Radiation produced by flat-panel C-arms varies dramatically, with the highest exposure (Ziehm) being almost double the lowest (Philips) in AEC. Improved picture quality may come at the cost of increased radiation dose. Surgeons must use care to select the device and settings to minimize radiation exposure while still maintaining adequate image quality.