[A bi-isocentric irradiation technique in radiotherapy for nasopharyngeal carcinoma].

Background & Objective: Although the problem of fields gap in radiotherapy for nasopharyngeal carcinoma (NPC) was solved by mono-isocentric technique, the dose distribution was heterogeneous with "hot" and/or "cold" spots. This study was to explore the best way to solve the problems of both fields gap and dose distribution using bi-isocentric technique.

Methods: Mono-isocentric and bi-isocentric irradiation techniques were used to simulate irradiation, respectively.