Comparison of biological-based and dose volume-based intensity-modulated radiotherapy plans generated using the same...

Nowadays, most of the radiotherapy (RT) treatment planning systems (TPSs) uses dose or dose-volume (DV)-based cost functions for Intensity modulated radiation therapy (IMRT) fluence optimization. Recently, some of the TPSs incorporated biological-based cost function for IMRT optimization. Most of the previous studies compared IMRT plans optimized using biological-based and DV-based cost functions in two different TPSs. Hence, the purpose of the study is to compare equivalent uniform dose (EUD)-based and DV-based IMRT plans generated using the same TPS.

Twenty patients with prostate cancer were retrospectively selected for this study. For each patient, two IMRT plans were generated using EUD-based cost function (EUD_TP) and DV-based cost (DV_Treatment Plan (TP)), respectively. The generated IMRT plans were evaluated using both physical and biological dose evaluation indices.

Biological-based plans ended up with a highly inhomogeneous target dose when compared to DV-based plans. For serial organs, D_near-max or D_2%(Gy) of EUD-based plans showed significant difference with DV-based plans (P = 0.003). For both rectum and bladder, there was a significant difference in mean dose and D_30%(Gy) dose between EUD-based plans and DV-based plans.

In this study, we decoupled the influence of optimization parameters from the potential use of EUD-based cost functions on plan quality by generating both plans in the same TPS.