Radiation Exposure of relatives of patients treated with Ra-223 dichloride in Germany - Results of the “RAPSODY” study

1456 Objectives The multicenter study "RAPSODY" was conducted to assess the radiation exposure of relatives and caregivers of patients suffering from CRPC with symptomatic bone metastases and treated with Ra-223 dichloride in an outpatient setting. As Ra-223 and most of its progeny emit alpha particles, the internal exposure had to be evaluated in particular. Methods The external radiation was measured in a distance of 1 and 2 m using standard dose-rate meters. Wipe-tests were taken in the patients’ homes to identify significant contaminations and evaluated by liquid scintillation counting. Samples of saliva and sweat were taken and measured using gamma spectrometry. The noble gas Rn-219 was measured in the exhaled breath from the patients using conventional Radon Monitors. The results of the exhalation measurements were used in a computational fluid dynamics simulation (CFD) to assess the radioactivity in the air, which could be inhaled by persons close to the patient. Results The external exposure from the patients measured 10-20 min p.i. was 0.05 μSv/h in median in 1 m distance (range: below detection limit ( Conclusions The potential exposure of relatives by external irradiation and incorporation of radioactivity exhaled or excreted by the patient with saliva or sweat is well below 1 mSv. No objections are seen regarding outpatient treatment.