13 Oropharynx

278 Oropharynx

When large tumours are implanted, the separation between the branches of the loops may exceed 20 mm in order to encompass the entire lesion. To prevent underdosage in the central area of the PTV, a frontal loop may be added, with its branches equidistant of those of the sagittal loops. The bridge of the frontal loop is not loaded to avoid high spot resulting from overlapping of sagittal and frontal loop (Fig 12.2).

Fig 12.2: Base of tongue implant. A: Anterior-Posterior view: the tubes are loaded with Ir 192 wires. B: Lateral view.

Fig 12.3: Base of tongue: modification of the implant technique for the vallecular region.