Purpose: The results of three-dimensional treatment planning using a computed tomography simulator were evaluated in patients with maxillary cancer.
Methods and materials: Treatment planning was done in 25 patients 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 films (1983-1987, group 2), in 24 patients using a computed tomography simulator (1988-1992, group 3). The number of patients with Stage IV disease increased in the order of group 1 to group 3.
Results: The average radiation field was smallest in group 3 (66.5 cm2) followed by group 2 (67.4 cm2) and group 1 (72.9 cm2). A radiation dose of more than 30 Gy to the lens of the effected side was delivered to 13% of group 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. However, a significant increase in survival was only noted between groups 1 and 2, because the three population of patients were different.
Conclusion: The three-dimensional treatment planning results in a better treatment than two-dimensional treatment planning as measured by complication rates and field sizes.