Clinical impact of the flattening filter free irradiation in fixed-field IMRT and VMAT for stage I–II nasal natural killer/T-cell lymphoma

Abstract

The study aimed to investigate clinical impact of the flattening filter free (FFF) irradiation in fixed-field intensity-modulated radiotherapy (IMRT) and volumetric-modulated arc therapy (VMAT) for patients with stage I-II nasal natural killer/T-cell lymphoma (NNKTCL). Four different plans, fixed-field IMRT, and VMAT plans with and without flattening filter (FF) (IMRT FF, IMRT FFF, VMAT FF, and VMAT FFF) were created for each of selected patients. Target quality, organs at risk (OARs) sparing, and tumor control probability (TCP) were compared between IMRT and VMAT with and without FF. The values of D 98% , V 95% , and conformal index were 0.03 Gy (P = 0.028), 0.03% (P = 0.048), and 0.002 (P = 0.002) lower with IMRT FFF than with IMRT FF, and the values of D 2% , D mean , and homogeneity index were 0.14 Gy (P = 0.018), 0.1 Gy (P = 0.007), and 0.002 (P = 0.008) higher with VMAT FFF than with VMAT FF. The TCP was higher with FFF beam than flattened beam in IMRT and VMAT. The results show that FFF irradiation achieved slightly worse target quality than FF irradiation in IMRT and VMAT for stage I-II NNKTCL. FFF beam was advantageous to increase the TCP in IMRT and VMAT.

Dosimetric and Radiobiological Impact of Flattening Filter‐Free Beam and Dose Calculation Algorithm Using RapidArc Plans for Cervical Cancer Treatment

“…Because the unflattened photon beam does not pass through the FF, the scattering and leakage radiation are lower than those of the flattened beam. In addition, FFF irradiation reduces delivery times in stereotactic treatments and lowers the secondary cancer risk in peripheral organs, which has been confirmed by many researchers 7,8 …”

“…In addition, FFF irradiation reduces delivery times in stereotactic treatments and lowers the secondary cancer risk in peripheral organs, which has been confirmed by many researchers. 7,8 With these advantages of FFF beams, many researchers have studied the dosimetry of FFF and FF beams for various sites and showed a reduction in the mean dose to normal tissue, sparing normal tissue and OAR without compromising the target coverage. 9 Therefore, evaluation of the radiobiological parameters of a treatment plan using dosimetric parameters is a comprehensive and rational approach.…”