Introduction/background: In conventional linear accelerators, to obtain flat profiles leading to uniform dose distribution in homogeneous medium, the flattening filter is usually applied on the beam path. In recent years, to obtain higher dose rates, there have been the options of flattening filter free (FFF) beams and it has been noticed that these have many advantages. The aim of this study was to clearly underline the advantages and the drawbacks of flattened filter free (FFF) beams in comparison with the flattening filter (FF) beams for different clinical contexts (planning target volumes locations).
Methods: Two groups (planned with auto-planning VMAT, full and partial arcs) of eight patients each were analyzed: Group I (small planning target volume PTV, with average volume 48.9 ±44.4 cm), Group II (large PTV, with average volume 532.4 ±368.8 cm). Both beam modalities 6MV and 6MVFFF were compared in terms of Dmax, D95%, D1cc, D2cc, homogeneity index (HI), number of monitor units (MU), treatment delivery time.
Results: Using the 6MVFFF, the treatment delivery time was significantly reduced (p<0.05). For larger PTVs, the number of MU increased by more than twice, and the p-value shown a significant difference (p= 0.008). The value of Dmax increased by 4%. On the contrary, for small volumes, the results were quite similar from 6MVFFF to 6MV except some differences in terms of MU.
Conclusion: It is recommended to use 6MVFFF beam with small PTV volumes. Dose distributions are almost the same as with 6MV and there is a significant reduction of the treatment delivery time up to 57%. Due to the dose profile shape in FFF mode, the dose is lowered beyond the central axis for the FFF beams, and the additional MU allows the dose to be delivered away from the beam axis.
Download full-text PDF |
Source |
|---|---|
| http://dx.doi.org/10.1016/j.jmir.2022.09.025 | DOI Listing |
Publication Analysis
Top Keywords
Similar Publications
Empty sella syndrome: an update.
Pituitary
December 2024
Dipartimento di Medicina Traslazionale, Università Cattolica del Sacro Cuore, Rome, Italy.
Introduction: Empty sella is characterized by a flattened profile of the pituitary gland that represents in most cases only a radiological incidental finding. When endocrine, ophthalmic, and neurological symptoms occur, this condition is described as empty sella syndrome.
Materials And Methods: We searched MEDLINE (PubMed database) with the data filter 2024-2009 using the keywords listed above.
Feasibility of volumetric-modulated arc therapy gating for cardiac radioablation using real-time ECG signal acquisition and a dynamic phantom.
Med Phys
December 2024
Department of Physics, The Verspeeten Family Cancer Centre, London, Ontario, Canada.
Background: Stereotactic arrythmia radioablation (STAR) is a noninvasive technique to treat ventricular tachycardia (VT). Management of cardiorespiratory motion plays an essential role in VT-STAR treatments to improve treatment outcomes by reducing positional uncertainties and increasing dose conformality. Use of an electrocardiogram (ECG) signal, acquired in real-time, as a surrogate to gate the beam has the potential to fulfil that intent.
View Article and Find Full Text PDFCorrection method for ionization chamber dosimetry in flattening filter free radiotherapy based on Monte Carlo simulation.
Med Phys
December 2024
Division of Ionizing Radiation Metrology, National Institute of Metrology (NIM), Beijing, China.
Background: The clinical use of flattening filter free (FFF) radiotherapy has significantly increased in recent years due to its effective enhancement of dose rates and reduction of scatter dose. A proposal has been made to adjust the incident electron angle of the accelerator to expand the application of FFF beams in areas such as large planning target volumes (PTVs). However, the inherent softening characteristics and non-uniformity of lateral dose distribution in FFF beams inevitably lead to increased dosimetry errors, especially for ionization chambers widely used in clinical practice, which may result in serious accidents during FFF radiotherapy.
View Article and Find Full Text PDFParallel generation of multi-channel chaos is critical to applications, and the key challenge is the simultaneous generation of broadband chaos with multiple channels and low correlation. Here, we experimentally demonstrate a parallel broadband chaos generation scheme using a single long-active-cavity Fabry-Perot (LC-FP) semiconductor laser under optical feedback. The active-cavity length is designed to be 1500 μm, so the power spectrum of chaos is expanded and flattened by the mode-beating effect.
View Article and Find Full Text PDFProsodic Preferences of Surface Electromyography-based Subvocal Speech for People With Laryngectomy.
J Voice
December 2024
Delsys, Inc., Natick, Massachusetts 01760; Altec, Inc., Natick, Massachusetts 01760; Department of Speech, Language and Hearing Sciences, Boston University, Boston, Massachusetts 02215. Electronic address:
Introduction: People who undergo a total laryngectomy lose their natural voice and depend on alaryngeal technologies for communication. However, these technologies are often difficult to use and lack prosody. Surface electromyographic-based silent speech interfaces are novel communication systems that overcome many of the shortcomings of traditional alaryngeal speech and have the potential to seamlessly incorporate individualized prosody.
View Article and Find Full Text PDFWant AI Summaries of new PubMed Abstracts delivered to your In-box?
Enter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!