Assessing medical radiation exposure in the German National Cohort


The aim of this project was to record medical radiation exposure in the NAKO Health Study both retrospectively and prospectively and to determine the respective medical indications. For this purpose, a Level 3 study was set up, which was conducted as an additional module to the NAKO baseline survey (Level 1 or Level 2) at four of the 18 study centers of the NAKO Health Study. In addition to the retrospective (lifetime) assessment of NAKO study participants using a questionnaire as an integral touch-screen module of the NAKO baseline survey routines, a follow-up was implemented to prospectively record radiological examinations performed since the study center visit.

The Leibniz Institute for Prevention Research and Epidemiology - BIPS in Bremen coordinated this multicenter level 3 study and also acted as the study center. Other participating institutions were the University Medical Center Greifswald (Study Center Neubrandenburg), the University Hospital Essen (Study Center Essen) and the Helmholtz Center for Environment and Health (Study Center Augsburg).

A total of 3,923 study participants (level 3 participation rate: 79%) were recruited at the four study centers and information on medical radiation exposure was recorded. The age range of the study participants was between 20 and 73 years. The mean age was 48.9 years. Approximately two-thirds of the study participants (n=2,717) reported having received at least one of the radiological examinations queried in the questionnaire in the past. Computed tomography (n=4,193; 41%), general radiography (n=2,573; 25%), and nuclear medicine diagnostics (n=1,490; 14%) represented a total of 80% of all reported examinations. There were only marginal gender differences.

As expected, age-typical patterns with increasing mean examination frequencies and increasing age group were observed. In the lowest age group (< 40 years), mainly (disease-) non-specific indications were reported (falls/accidents, spinal pain). In addition, thyroid scintigraphs were relatively frequent. In the middle age group (40-50 years) thyroid scintigraphs were notably more frequent, as well as more fluoroscopies were reported (indication: unspecific, imaging of the gastrointestinal tract). Examinations due to herniated discs and spinal pain became more significant. In the age group >50 years, age-related indications such as spinal pain, herniated discs continued to gain importance. In addition, interventional X-ray examinations and fluoroscopies were reported more frequently (indication: cardiac catheterization, skeleton/bone, lung/heart/kidney; imaging of the gastrointestinal tract).

A total of 2,964 follow-up questionnaires from 2,208 study participants were available for the follow-up period (follow-up participation rate: 56%). 28% (n=626) of the study participants reported further radiological examinations received in the meantime (n=1,245). General radiographic examinations (n=757, 61%), computed tomography scans (n=292, 23%), and nuclear medicine diagnostics (n=90, 7%) represented more than 90% of all reported examinations since the study center visit. In addition, 2,375 NAKO radiographic passports were available from 1,707 study participants. Of these, 299 (12.6%) radiographic passports contained 480 features of relevant examinations. The availability of stated dose parameters was extremely low. The proportion of registered dose parameters in all relevant examinations was only 40% (190 of 480 relevant examinations) and of insufficient quality.

Funding period

Begin:   May 2017
End:   September 2019


  • Federal Office for Radiation Protection


 Steffen Dreger