High-dose boost irradiation techniques for carcinoma of the nasopharynx

Irregularly shaped tumors of the nasopharynx require the capacity to design flexible and reproducible treatment plans for high-dose boost irradiation. We use a variety of external beam techniques which may be combined with an afterloading intracavitary implant. Careful planning of such treatment is crucial and requires an accurate assessment of tumor volume and regional anatomy as defined by lateral simulator films, computed tomography, and magnetic resonance imaging scans. External beam irradiation is performed using a variety of arc rotations or fixed-beam cross-fire techniques in order to maximize the dose to an irregular tumor volume while minimizing irradiation of sensitive neighboring structures. Intracavitary implantation is achieved by constructing a mold of the nasopharynx with a silastic polymer and fitting it with hollow plastic catheters for afterloading with iridium-192.