EP-1670: Impact of flatting filter free photon beam on Rapid-arc radiotherapy for gynecological malignancies
Radiotherapy and Oncology
S780 ESTRO 35 2016 _____________________________________________________________________________________________________ Gy in 28 fractions. Plans were evaluated based on the ability to meet the dose volume histogram. The homogeneity index (HI), conformity index (CI) of target volume, the dose of organs at risk, radiation delivery time and monitor units were also compared. Paired T-test model analysis was used to analyse the two sets of data. Purpose or Objective: The purpose of this study is
... of this study is to investigate the treatment plan dosimetry and delivery efficiency between the single-arc and double-arc techniques using stereotactic body radiotherapy with flattening filter free beams for early-stage lung cancer. Material and Methods: Nineteen patients were included in this investigation, and each patient was arranged singlepartial-arc (SA) and double-partial-arc (DA) techniques using the Eclipse 10.0 treatment planning system. The prescription dose was 48Gy/4 fractions and the photon beam energy was 6 MV flattening filter-free (FFF) beams from Truebeam linear accelerator. The treatment plans were appraised by Radiation Therapy Oncology Group (RTOG-0915) criteria for planning target volume (PTV) coverage and organs at risk (OAR) sparing. All plans were normalized to 100% of prescribed dose at least covering 95% of the PTV. Treatment efficiency was evaluated via monitor units (MUs) and treatment times were compared. Results: The PTV volumes range from 20.46 to 88.37 cm3. Compared to the SA and DA plans, there was no significant difference in PTV coverage, except the maximum dose in the PTV. The maximum dose of SA technique was slightly higher than that of DA technique. The mean PTV conformity index (CI) for SA and DA was 1.06±0.05 and 1.01±0.03 respectively.