High dose rate endobronchial brachytherapy using a new applicator.

BACKGROUND AND PURPOSE

To obtain adequate spatial dose distribution for endobronchial brachytherapy, we applied reference dose points according to the bronchial diameter. For this purpose, we devised a new applicator of which the source transfer tube is contained in the center of the lumen for high dose rate (HDR) brachytherapy.

MATERIALS AND METHODS

Thirty-nine patients with endobronchial cancer underwent endobronchial brachytherapy using an HDR afterloading machine with an Ir-192 source. In the nine patients treated with curative intent, treatment consisted of external beam radiotherapy with 40-60 Gy for 4-6 weeks and endobronchial brachytherapy with three fractions of 6 Gy. The 30 patients 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 caliber.

RESULTS

The new applicator could be placed at the intended site in 37 lesions. Of 12 lesions which were treated with curative intent, eight (67%) disappeared after brachytherapy. The overall survival at 3 years of all patients and of the patients treated with curative intent was 22 and 64%, respectively.

CONCLUSIONS

The source should be positioned in the center of the lumen; this technique is helpful in reducing side-effects caused by inhomogeneous dose distribution of endobronchial brachytherapy.