A application study of dose constraint template in intensity modulated radiation therapy planning for early stage nasopharyngeal carcinoma

Objective: To investigate a feasibility of using dose constraint template (DCT) to increase conformity index (CI) of planning target volume (PTV) and improve intensity modulated radiation therapy (IMRT) planning efficiency for early stage nasopharyngeal carcinoma. Methods: Ten patients with pathological diagnosed and treated by IMRT were selected for this study. Target volumes were delineated with Corvus 6.3 of treatment planning system, two dose limiting regions(DLR) around PTV were added by extending from PTV, each DLR was 1 cm thick. We created three plans:Plan0, Plan1 and Plan2. Plan0 was without DLR and DCT, Plan1 without DLR but with DCT, Plan2 with both condition; but to compare dose distribution in PLTV and normal tissue using three plans. Results: Three plans could fill equal request of dose distribution in PLTV and normal tissue, and their difference was not statistical significant. CI of Plan2 was increased and planning time was decreased significantly compared with Plan0 and Plan1. Conclusion: Usage of' DCT together with DLR can increase CI of PTV and improve IMRT planning efficiency for early stage nasopharyngeal carcinoma, planning time is shortened significantly. (authors)