Establishing local diagnostic reference levels for pediatric percutaneous transhepatic cholangiography interventions and optimizing the routine practice

Liver-transplanted, immunosuppressed pediatric patients undergoing repeated percutaneous transhepatic cholangiography (PTC) require optimized exposure to ionizing radiation. To establish local diagnostic reference levels (DRL) for pediatric PTC and investigate the routine use of X-ray equipment. The study retrospectively analyzed data collected between October 2016 and June 2018 from a single center performing PTC. We collected exposure parameters including kerma area product (PKA), air kerma at patient entrance reference point (Ka,r) and fluoroscopy time via a dose archiving and communication system. Local diagnostic reference levels were derived as the 50th percentile of the distributions while considering published recommended weight groups. We investigated exposure variability with procedure complexity and with technical parameters recovered from the radiation dose structured report. The analysis included 162 PTC procedures performed in 64 children: 58% male, average age 6 years (range 39 days to 16 years) and weight 24 kg (range 3–60 kg). Local DRLs for weight groups 0–5 kg, 5–15 kg, 15–30 kg, 30–50 kg and 50–80 kg were, respectively, 6 cGy.cm2, 22 cGy.cm2, 68 cGy.cm2, 107 cGy.cm2 and 179 cGy.cm2 in PKA. Local DRLs per weight group were also established for intermediate and complex procedures. Radiation dose structured report analysis highlighted good local practice with efficient collimation, low fluoroscopy pulse rate, no magnification and limited use of radiographic acquisitions. Meanwhile, table and detector positioning and tube projection could still be optimized. PKA correlated significantly with the number of acquisitions and tube-to-table distance. We established local DRLs for children undergoing PTC.