Patient effective dose from endovascular brachytherapy with Ir-192 sources

The growing use of endovascular brachytherapy has been accompanied by the publication of a large number of studies in several fields, but few studies on patient dose have been found in the literature. Moreover, these studies were carried out on the basis of Monte Carlo simulation. The aim of the present study was to estimate the effective dose to the patient undergoing endovascular brachytherapy treatment with Ir-192 sources, by means of experimental measurements. Two standard treatments were taken into account: an endovascular brachytherapy of the coronary artery corresponding to the activity x time product of 184 GBq.min and an endovascular brachytherapy of the renal artery (898 GBq.min). Experimental assessment was accomplished by thermoluminescence dosemeters positioned in more than 300 measurement points in a properly adapted Rando phantom. A method has been developed to estimate the mean organ doses, for all tissues and organs concerned in order to calculate the effective dose associated with intravascular brachytherapy. The normalised organ doses resulting from coronary treatment were 2.4 X 10(-2) mSv.GBq(-1).min(-1) for lung, 0.9 X 10(-2) mSv.GBq(-1).min(-1) for oesophagus and 0.48 X 10(-2) mSv.GBq(-1).min(-1) for bone marrow. During brachytherapy of the renal artery, the corresponding normalised doses were 4.2 X 10(-2) mSv.GBq(-1).min(-1) for colon, 7.8 X 10(-2) mSv.GBq(-1).min(-1) for stomach and 1.7 X 10(-2) mSv.GBq(-1).min(-1) for liver. Coronary treatment involved an effective dose of 0.046 mSv.GBq(-1).min(-1), whereas the treatment of the renal artery resulted in an effective dose of 0.15 mSv.GBq(-1).min(-1); there were many similarities with data from former studies. Based on these results it can be concluded that the dose level of patients exposed during brachytherapy treatment is low.