Over a period of one month, the radiation exposure of staff during 61 diagnostic and therapeutic radiological interventions at the LMU University Hospital in Munich was measured using a real-time dosimetry system (RaySafe i3, Unfors RaySafe, Sweden) (Fig. 1). 
The interventions included
- 25 general radiological angiographies (ANG),
- 17 angiographies in the cardiac catheterization laboratory (Cath Lab),
- 11 CT-guided interventions (CTI),
- and 8 procedures in neuroradiology (NRAD).
For each intervention the dose of every staff member was measured using real-time dosimeters placed at chest height over the lead apron and shown on a screen in the interventional suite (Fig. 2).
The dose accumulated per intervention was recorded separately for four personnel categories:
- interventionists (IR),
- radiology residents (RR),
- first radiology technicians (RT1),
- and second radiology technicians (RT2).
Not all roles were occupied during each intervention and for any intervention the measured dose for a role was only considered in the statistical evaluation if it was occupied during the entire duration of the intervention.
We then conducted a statistical analysis of the relationship between the
- accumulated dose per intervention and the professional role (IR, RR, RT1 and RT2),
- and the total accumulated dose per intervention for the entire team and the type of intervention (ANG, Cath Lab, CTI and NRAD).
We used the Kruskal-Wallis test to assess whether there were any significant differences between the distributions of dose values of the observed groups. Post hoc pair-wise comparisons of groups were performed using Dunn’s test with Holm-Bonferroni correction. P-values less than 0.05 were considered significant.