Radiation Risk from Intracoronary Brachytherapy

While chlinical and physical aspects of endovascular brachytherapy are addressed in literature, there is little information available on radiation risk for the patient and and the personnel involved in this new treatment modality. The dose rate from endovascular brachytherapy sources at distances of organs at risk is calculated using analytical methods and Monte Carlo simulations (EGSnrc). Additionally, internal dose calculations are performed using the MIRDOS software. Results are compared with exposure levels due to angiography published in literature. In order to optain dose estimates for the personnel involved in the procedure the dose rate is measured at several locations inside and around the cath-lab. Additionally the personnel involved in endovascular brachytherapy is equipped with electronic dose meters for 15 interventions. The results obtained with different calculation methods are in very good agreement. For gamma emitting sources the radiation exposure to patients is in the order of magnitude of the exposure due to diagnostic angiography. Measured doses for the intervention personnel are on average 6 µSv, 3 µSv and 0.7 µSv for the radiotherapist, physicist and personnel in the control room, respectively. These values are mcuh less than 0,1% of the annual radiation worker's Maximum Permissible Dose (MPD) recommended by EC regulations. There is an additional radiation exposure to patients and personnel caused by endovascular brachytherapy, but the values are much smaller than those caused by diagnostic angiography. The exposure to organs at risk due to 2 PTCA procedures is already higher than one PTCA plus brachytherapy.