RESUMO
Objective:To compare the dosimetric difference between knowledge-based planning (KBP) volumetric modulated arc therapy (VMAT) and intensity-modulated radiotherapy (IMRT) models for predicting the dose distribution during IMRT, aiming to investigate the feasibility of VMAT model to predict the IMRT plans.Methods:Fifty prostate cancer patients who had completed radiotherapy were selected. Manual planning was performed on each selected patient to generate the corresponding IMRT and VMAT plans. The IMRT and VMAT manual plans of the 40 randomly-selected patients were adopted to generate the KBP VMAT and IMRT models. The remaining 10 patients were utilized to predict IMRT plans. VMAT library-derived IMRT model (V-IMRT) and IMRT library-derived IMRT model (I-IMRT) were generated. Dosimetric parameters related to organ-at-risks (OARs) and planning target volume (PTV) were statistically compared among the manual IMRT (mIMRT), V-IMRT and I-IMRT plans.Results:Compared with the mIMRT plan, I-IMRT could significantly better control D max of the PTV ( P=0.039), whereas V-IMRT and I-IMRT plans could better protect the bladder and bilateral femoral heads (both P<0.05). V-IMRT plan could better protect the D max of bilateral femoral heads and the D 15% of the right femoral head (both P<0.05), whereas no significant difference was observed in other OARs and PTV (all P>0.05). Conclusions:Compared with the manual plans, KBP IMRT plan has significant advantages in protecting the OARs. KBP VMAT and IMRT models are both feasible in clinical practice, which yield equivalent accuracy for predicting IMRT plan.