3-DIMENSIONAL TREATMENT PLANNING FOR MAXILLARY CANCER USING A CT SIMULATOR

Purpose: The results of three-dimensional treatment planning using a c omputed tomography simulator were evaluated in patients with maxillary cancer. Methods and Materials: Treatment planning was done in 25 pati ents using an x-ray simulator and plain x-ray films (1979-1982, group 1) in 34 patients using an x-ray simulator and computed tomography fil ms (1983-1987, group 2), in 24 patients using a computed tomography si mulator (1988-1992, group 3). The number of patients with Stage IV dis ease increased in the order of group I to group 3. Results: The averag e radiation field was smallest in group 3 (66.5 cm(2)) followed by gro up 2 (67.4 cm(2)) and group 1 (72.9 cm(2)). A radiation dose of more t han 30 Gy to the lens of the effected side was delivered to 13% of gro up 3, 44% of group 2, and 44% of group 1. The dose to the lens on the uneffected side was zero in 56% of group 1, 74% of group 2, and 96% of group 3. A long-term decrease in visual activity on the effected side occurred in 11% of group 3, 32% of group 2, and 44% of group 1. Howev er, a significant increase in survival was only noted between groups I and 2, because the three population of patients were different. Concl usion: The three-dimensional treatment planning results in a better tr eatment than two-dimensional treatment planning as measured by complic ation rates and field sizes.