Patient and personnel dosimetry in endovascular radiotherapy with 90Sr/90Y sources

Endovascular brachytherapy (EVBT) is an established treatment to reduce the probability of restenosis after a percutaneous coronary intervention. The purpose of this study was to assess (1) the manufacturer's stated dosimetric data for (90)Sr/(90)Y source trains to be used in EVBT and (2) the procedure-related radiation burden. The radiation fields in water around six (90)Sr/(90)Y source trains were studied using phantoms made of 'solid water' and MD55-2 radiochromic films. The water equivalence of the phantom material was tested by applying quantitative computed tomography. Thermoluminescence dosemeters were used to assess personal radiation burden and crosscheck the dose distribution along the source trains. Technical failure was observed in one source train and this train was excluded from analysis. The measured dose rate in water at 2 mm radial distance was on average 8% higher than the manufacture's stated value (range of measured to stated values 1.05--1.15). The dose rate decreased exponentially with radial distance between 2 and 6 mm. The dose rate in contact with the source viewing window of the delivery devices ranged between 0.5 and 7.5 mGy h(-1). Low-energy photons were the main contributors to personal dose.