Aims: to determine the radiation exposure of routine intraoperative cholangiography (IOC )during cholecystectomy and examine the factors affecting radiation dose and fluoroscopy time (FT).

Methods: 598 intraoperative cholangiography examinations were performed at the Central Finland Central Hospital. In this study we included 324 intraoperative cholangiographies performed with c-arm equipment not exceeding 10 years of age.

From January 2016 to December 2017, consecutive 598 intraoperative cholangiography examinations were performed at the Central Finland Central Hospital. In this study we included 353 cholangiographies, that were performed with our c-arm equipment not exceeding 10 years of age in the beginning of 2016. The main measures of outcome were the recorded radiation dose data of c-arm systems from our manual database .

Another 25 cases were excluded because it was not possible to cross-check the manually recorded radiation dose data from the Picture Archiving and Communication System (PACS ). Additional 4 patients who underwent intraoperative endoscopic retrograde cholangiopancreatography (ERCP) were removed from the radiation exposure analysis because IOC and ERCP were performed consequently with the same c-arm and the radiation exposure of IOC could not be separated from the registered total KAP and FT. Thus the final analysis consisted of 324 IOCs. KAP (Kerma area product) is the product of air Kerma in the center of the imaging area multiplied with size of the imaging area. For simplicity we have unified varying units received from different c-arms and will only use Gray multiplied by square centimeters (Gycm2 ). KAP values were measured using inbuilt ionization chambers in c-arms. For this study we collected the KAP values from exposure and pulsed fluoroscopy. We also recorded the fluoroscopy time (s).

Laparoscopic cholecystectomies were performed both by residents and specialist surgeons.

Ethics: No ethical approval or written informed consent were needed because the study was retrospective in nature. The study was approved by the hospital administration.

Inclusion Criteria:

• Consecutive intraoperative cholangiographies performed with c-arm equipment not exceeding 10 years of age between January 2016 to December 2017

Exclusion Criteria:

• intraoperative cholangiographies performed with c-arm equipment exceeding over 10 years of age between January 2016 to December 2017
• patients who underwent intraoperative endoscopic retrograde cholangiopancreatography (ERCP)
• if the manually recorded radiation dose data could not be cross-checked from the Picture Archiving and Communication System ( PACS ) system

Patients who underwent laparoscopic , open or conversion cholecystectomy with intraoperative cholangiography