Document Type : Original Paper
Authors
1
Department of Physics, Research Scholar, Karunya Institute of Technology and Sciences, Coimbatore, India
2
Department of Physics, School of Sciences, Arts, Media and Mangement, Karunya Institute of Technology and Sciences, Coimbatore-641 114 Tamilnadu India
3
Radiation Oncology Department, Senior Consultant, Aster Mims Hospital, Calicut, India
4
Chief Medical Physicist Department of Radiation Oncology Fortis Hospital, Sector 62, Phase 8, SAS Nagar, Mohali-160062, Punjab India
Abstract
Introduction
In this work, we compared the dosimetric features and delivery efficiency of Fractionated Stereotactic Radiotherapy (FSRT) plans for the brain that used Flattening Filter (FF) and Flattening Filter Free (FFF) beams of 6 MV and 10 MV energies.
Materials and Methods
In order to treat a primary Brain Metastasis (BM), twelve patients were selected and given 25 Gy in five fractions. To cure tumors quickly, 6FF beams were angled in a double arc. The Planning Target Volume (PTV) and Organs at Risk (OARs) were assessed using a number of dosimetric indices after each plan was reproduced and replanned with 6 FFF, 10 FF, and 10 FFF energies. Treatment time (TT) and Monitor Units (MUs) usage were only two of several clinical characteristics compared. Additionally, we compared the portal dose image prediction (PDIP) and portal dosimetry measurement for dose agreement across all plans using the gamma analysis criterion of 3%/3mm of Dose Difference/ Distance to Agreement (DD/DTA).
Results
Most of the PTV parameters of created plans showed better values when compared to 6 FF plans, where the most significant is with FFF plans which include the D98%, D80%, D2%, D50% and Dose Gradient Index values of 6FFF plans. Among OARs, the most significant is the V10 value of (Brain-PTV) as (46.77±43.9) and also the maximum dose values of optic chiasm, brainstem and left lens in 6FFF plans. Among technical parameters, the 6FFF plan showed a significant TT value of (3.06±1.0) with p-value 4.13E-05. Better gamma analysis passing rates were achieved with FFF beams during portal dosimetry plan verification compared to FF beams.
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