Application of equivalent uniform dose optimization in the treatment of rectal cancer with intensity-modulated radiotherapy

Objective: Comparing the dosimetric differences between equivalent uniform dose based bio-optimization and dose-volume based physical optimization in retrograde intensification therapy plans for rectal cancer, and exploring the plan optimization methods on plan quality. Methods: Among the rectal cancer patients of 15 cases who had already undergone intensified radiotherapy were randomly selected. Three reverse intensified radiotherapy plans were formulated according to different optimization methods by the Varian Eclipse treatment planning system, in which group A used traditional dose volume (DV) physical optimization, group B adopted equivalent uniform dose (EUD) bio-optimization, and group C was optimized by adding biological optimization (DV + EUD) to the physical optimization. The dosimetric differences among the three optimization methods were compared and evaluated by dosimetric parameters. Results: There were no statistically significant differences in the planing target volume (PTV) dosimetric indicators of the three groups (P > 0.05). In the protection of bladder and femoral head, there was no significant difference between group B and group C (P > 0.05) and both of them were better than group A (P < 0.01). In protecting the small intestine, group C was better than group B (P < 0.05), group B and group C was significantly better than group A (P < 0.01). Conclusion: Simultaneously using physical and biological optimization in intensity modulated radiation therapy planning for rectal cancer can better protect endangered organs in the premise of meeting target area dose requirements. (authors)