What is it about?
Purpose The aim of this study is to quantify the potential benefits of a flattening filter-free (FFF) beam and implement a dose-computation algorithm for cervical radiotherapy through dosimetric and radiobiological analyses using RapidArc. Methods Thirty-three patients were enrolled, and four RapidArc plans were created for each patient using a dual-arc flattening filter and 6-MV FFF photon beams for the two calculation algorithms. Homogeneity index (HI), conformity index (CI), target coverage, monitor units (MUs), and organ-at-risk (OAR) dosimetric characteristics were compared between the plans. Radiobiological characteristics and normal tissue complication probability (NTCP) scores were computed for the OAR using different biological models. Results No significant differences were observed in the Dmax, D98%, and CI in the planning target volume (PTV). Both computations estimated a significant difference in V95%, D2%, and HI for the PTV. Furthermore, the FFF beam showed a significant increase in the MUs and a significant reduction in V30% for the femoral heads. The NTCP score showed a significant increase in the late effects on the bladder, rectum, and bowel with FFF beams. Conclusion The current study recommends FFF beams for better conformity, comparable dose coverage for the target, and OAR sparing invariable to the dose computation algorithm. The difference in the NTCP score for OAR was minimal with the FFF beam.
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Why is it important?
The evaluation of the radiobiological parameters of a treatment plan using dosimetric parameters is a comprehensive and rational approach. Hence, the present study aims to quantify the potential benefits of the FFF beam and dose computation algorithms (AXB and AAA) on cervical radiotherapy using the RapidArc technique compared with the FF beam.
Perspectives
The FFF beams yielded equivalent results in the target volume coverage with a homogeneous dose distribution and better conformity than the FF beam for both dose computation algorithms (AAA and AXB). In addition, the difference in mean dose-volume parameters for OAR was minimal, although a significant decrease was observed in the femoral heads. Furthermore, radiobiological analysis showed a significant increase in the NTCP score, even though the mean difference was minimal. In conclusion, a 6-MV flattening filter-free X-ray beam generates dosimetrically and clinically acceptable plans using the RapidArc technique.
Sumanta Manna
Kalyan Singh Super Specialty Cancer Institute
Read the Original
This page is a summary of: Dosimetric and Radiobiological Impact of Flattening Filter‐Free Beam and Dose Calculation Algorithm Using RapidArc Plans for Cervical Cancer Treatment, Precision Radiation Oncology, August 2023, Tsinghua University Press,
DOI: 10.1002/pro6.1207.
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