New bougie applicator system for intraluminal "high dose rate" afterloading radiotherapy of esophageal carcinoma.

Abstract

Applicators used to date in endoluminal "high dose rate" (HDR) afterloading (AL) radiotherapy of esophageal carcinoma consist of hollow plastic probes with an average thickness of 4 mm (1.8-5.0 mm), the diameter of which, however, often strongly deviates from that of the lumen of the tumor stenosis. Consequently, the probe can occupy an eccentric position in the esophagus. Exact dosimetry in the tumor region thus becomes virtually impossible, since the dose of the iridium emitter drops significantly with increasing distance (> 60% at a distance of 5 mm from the surface of the 4 mm probe). The bougie-type afterloading applicators developed by our group, however, offer a number of distinct advantages in comparison to conventional applicator probes: 1. Precise positioning of the applicator in the stenosis with simultaneous bougie effect. 2. Exact centering of the radiation source in the lumen of the esophagus. 3. Individual adaptation of the applicator size to the diameter of the residual lumen resulting from the tumor. 4. Upon patient-specific adaptation of the radiation exposure period, a distinct reduction of the surface (mucosa) dose is achieved together with simultaneous enhancement of the depth effect of radiotherapy treatment. Using these new afterloading bougies in over 150 treatment sessions involving 55 patients, no complications were thus far observed.