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 excentric
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.
