HIGH-DOSE-RATE ENDOBRONCHIAL BRACHYTHERAPY USING A NEW APPLICATOR

Background and purpose: To obtain adequate spatial dose distribution f or endobronchial brachytherapy, we applied reference dose points accor ding to the bronchial diameter. For this purpose, we devised a new app licator of which the source transfer tube is contained in the center o f the lumen for high dose rate (HDR) brachytherapy. Materials and meth ods: Thirty-nine patients with endobronchial cancer underwent endobron chial brachytherapy using an HDR afterloading machine with an Ir-192 s ource. In the nine patients treated with curative intent, treatment co nsisted of external beam radiotherapy with 40-60 Gy for 4-6 weeks and endobronchial brachytherapy with three fractions of 6 Gy. The 30 patie nts treated with palliative intent received one fraction of 10 Gy with or without external beam irradiation. The reference dose points were prescribed according to bronchial diameter, which was measured by the applicator's radiopaque wing expansion reflecting the bronchial calibe r. Results: The new applicator could be placed at the intended site in 37 lesions. Of 12 lesions which were treated with curative intent, ei ght (67%) disappeared after brachytherapy. The overall survival at 3 y ears of all patients and of the patients treated with curative intent was 22 and 64%, respectively. Conclusions: The source should be positi oned in the center of the lumen; this technique is helpful in reducing side-effects caused by inhomogeneous dose distribution of endobronchi al brachytherapy. (C) 1997 Elsevier Science Ireland Ltd.