Percutaneous transhepatic biliary drainage (PTBD) procedures are associated with an elevated radiation exposure for the patient. In the recently published guideline of the Federal Office for Radiation Protection in Germany diagnostic reference levels (DRLs) for dose area products (DAP) are not defined for PTBD procedures due to insufficient data. The aim of this retrospective study is to give a nation-wide survey on patients radiation exposure in different PTBD procedures considering factors that may have an impact on increased radiation exposure like fluoroscopic-guided versus ultrasound-guided bile duct puncture.

Percutaneous transhepatic biliary drainage (PTBD) procedures are associated with an elevated radiation exposure for the patient. Usually, radiation exposure in radiological interventions is measured by the dose area product (DAP). Diagnostic reference levels (DRLs) are based on the third quartiles (Q3) of the pooled dose area product (DAP) for the known interventional procedures. They have been introduced in the 1980s by the International Commission on Radiological Protection's (ICRP's) to reduce patients radiation exposure. In the recently published guideline of the Federal Office for Radiation Protection in Germany in 2016 DRLs are not defined for PTBD procedures due to insufficient data. Procedure complexity due to different techniques, patient anatomy, lesion characteristics and disease severity makes it difficult to define DRLs in this fluoroscopy-guided intervention. The ICRP recently published some recommendations on DRLs in medical imaging including radiological interventions. As DRLs are often missing in this field, it was suggested to analyze national data sets comprising dosimetric data from a large number of facilities. The aim of this retrospective study is to give a nation-wide survey on patients radiation exposure in different PTBD procedures considering factors that may have an impact on increased or decreased radiation exposure like fluoroscopic-guided versus ultrasound-guided bile duct puncture. A questionnaire was sent to 200 gastroenterological and radiological departments in university and non-university hospitals to analyze the last 10 - 30 consecutively performed PTBD procedures.

Inclusion Criteria:

• 10 up to 30 consecutively performed PTBDs are documented in the study center
• body weight of the examined patients is about 60 - 80 kilogramms
• returned questionaire is complete in regard to DAP, fluoroscopy time, number of still images, characters of the intervention, characterization of the fluoroscopy device (manufacturer, date of first registration)

Exclusion Criteria:

• the study center performs less than 10 PTBDs/year
• returned questionaire is incomplete

All consecutively performed PTBDs in each study center are included taking account of the exclusion/inclusion criteria