Comparison of Moderate Hypofractionated Volumetric-Modulated Arc Therapy Plans With and Without Flattening Filter for Localized Prostate Cancer

Abstract

Background/Aim The aim of this study was to compare volumetric-modulated arc therapy (VMAT) radiation plans between conventional VMAT with flattening filter (cFF-VMAT) and flattening filter-free VMAT (FFF-VMAT) for localized prostate cancer. Materials and methods Ten patients with localized prostate cancer who underwent cFF-VMAT at Yokosuka General Hospital Uwamachi, Yokosuka, Japan, from July 2020 to October 2020 were enrolled. Dose-volume histogram (DVH) parameters of the target volume, normal organs, monitor units (MU), and beam-on time (BOT) were compared between cFF-VMAT and FFF-VMAT plans. Results No significant difference was observed for DVH parameters for the target volume. No significant difference was observed in all parameters for the bladder and rectum between the cFF-VMAT and FFF-VMAT groups. The mean values of MU were 686 ± 52 and 784 ± 80 in cFF-VMAT and FFF-VMAT, respectively (p < 0.001). The mean BOT was 97.0 ± 6.6 s and 72.9 ± 1.4 s for cFF-VMAT and FFF-VMAT, respectively (p < 0.001). Conclusion DVH parameters of the target volume and normal organs were not significantly different between the cFF-VMAT and FFF-VMAT plans. In FFF-VMAT, MU was significantly higher, and the BOT was significantly shorter than those in cFF-VMAT.

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

“…on moderately hypofractionated VMAT with FFF beams for localized prostate cancer found no significant differences in DVH parameters for the target volume and in all parameters for the bladder and rectum. 16 Furthermore, IMRT with a FFF beam can achieve dosimetrically and clinically acceptable plans, as reported by Tamilarasu et al 14 In a similar study, Kumar et al performed a feasibility study on RapidArc plans using FFF beam, which yielded similar target coverage and a significant increase in the target mean dose for cervical cancer. 15 Zhang et al dosimetrically evaluated patients with cervical cancer after hysterectomy and found similar targets and OAR sparing using VMAT with FFF beams.…”

“…A recent study by Takakusagi et al. on moderately hypofractionated VMAT with FFF beams for localized prostate cancer found no significant differences in DVH parameters for the target volume and in all parameters for the bladder and rectum 16 . Furthermore, IMRT with a FFF beam can achieve dosimetrically and clinically acceptable plans, as reported by Tamilarasu et al 14 .…”