[Development of a system for risk analysis in treatment with unsealed radioactive substances in nuclear medicine]

With respect to the amendment of the Radiation Protection law it is required to estimate the risks of treatments with ionizing radiation regarding patient safety. This task is in the responsibility of a medical physics expert.

The risks were estimated using the Failure Mode and Effects Analysis (FMEA) as suggested by the Federal Office for Radiation Protection (BfS) and the scientific societies. For Radioiodine Therapy, Radiosynoviorthesis, Peptide Receptor Radionuclide Therapy, and Selective Internal Radiation Therapy, respectively, the involved processes were analyzed, structured and scored. This was done both individually by all people involved in the process and by all participants together. For processes with risk priority numbers > 125 countermeasures were introduced. The risk priority number (RPZ) was calculated as the product of severity of the event, the probability of the occurrence of the event and the detection probability.

The greatest risks were mistaken identity, incorrect estimations of activity and organ masses and a lack of compliance of the patients. The individual risk estimation revealed a high variability between the different professions, that was reduced significantly by discussion led by an external moderator. For the highest RPZ countermeasures were formulated which impact needs to be reviewed in the future.

Nuclear medical therapies were assessed as very safe, the revealed risks are very low in respect to patient safety. FMEA method was a useful tool to identify processes with potential for optimization. The chosen procedure can be easily adopted in other nuclear medicine facilities considering structure specific aspects like technical and personal equipment and procedures. Then further risks might be detected or the here identified risk might be assessed differently.