Purpose: The purpose of this study was to study the field size effect on the estimated Relative Biological Effectiveness (RBE) for carbon scanning beam irradiation.
Methods: A silicon-on-insulator (SOI) microdosimeter system developed by the Centre for Medical Radiation Physics, University of Wollongong, Australia, was used for lineal-energy measurements (microdosimetric quantity). The RBE values were derived based on the modified microdosimetric kinetic model (MKM) at different depths in a water phantom in the scanning carbon beam for various scanned areas.
Results: Our study shows that the difference in RBE values derived from the SOI microdosimeter measurements with the MKM model and from the Treatment Planning System (TPS). The difference of the RBE values is within 6.5 % at the peak point of the spread-out Bragg Peak (SOBP) region. Compared to the spot-beam, RBE values obtained in the scanned-beam with a larger scanned area of 1.0 × 1.0 cm have better agreement with which estimated by the TPS.
Conclusions: This study shows the possibility of using the SOI microdosimeter system as a quality assurance (QA) tool for RBE evaluation in carbon-pencil beam scanning radiotherapy.
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http://dx.doi.org/10.1002/mp.13924 | DOI Listing |
Phys Med Biol
January 2025
Department of Accelerator and Medical Physics, National Institutes for Quantum Science and Technology, 4-9-1 Anagawa, Inage-ku, Chiba, 263-8555, JAPAN.
The tumor microenvironment characterized by heterogeneously organized vasculatures causes intra-tumoral heterogeneity of oxygen partial pressure at the cellular level, which cannot be measured by current imaging techniques. The intra-tumoral cellular heterogeneity may lead to a reduction of therapeutic effects of radiation. The purpose of this study was to investigate the effects of the heterogeneity on biological effectiveness of H-, He-, C-, O-, and Ne-ion beams for different oxygenation levels, prescribed dose levels, and cell types.
View Article and Find Full Text PDFPhys Med Biol
December 2024
Centre for Medical Radiation Physics, University of Wollongong, Northsfield Ave., Wollongong, New South Wales, 2522, AUSTRALIA.
The recently developed V79-RBEbiological weighting function (BWF) model is a simple and robust tool for a fast relative biological effectiveness (RBE) assessment for comparing different exposure conditions in particle therapy. In this study, the RBEderived by this model (through the Particle and Heavy Ion Transport code System (PHITS) simulated d(y) spectra) is compared with values of RBEusing experimentally derived d(y) spectra from a silicon-on-insulator (SOI) microdosimeter. Approach: Experimentally measured d(y) spectra are used to calculate an RBEvalue utilizing the V79-RBEBWF model as well as the modified microdosimetric kinetic model (MKM) to produce an RBE-vs-ytrend for a wide range of ions.
View Article and Find Full Text PDFFront Oncol
November 2024
Department of Radiation Oncology, Penn State University Cancer Institute, Hershey, PA, United States.
We aimed to develop a comprehensive proton relative biological effectiveness (RBE) model based on accumulated cell survival data in the literature. Our approach includes four major components: (1) Eligible cell survival data with various linear energy transfers (LETs) in the Particle Irradiation Data Ensemble (PIDE) database (72 datasets in four cell lines); (2) a cell survival model based on Poisson equation, with and defined as the ability to generate and repair damage, respectively, to replace the classic linear-quadratic model for fitting the cell survival data; (3) hypothetical linear relations of and on LET, or and ; and (4) a multi-curve fitting (MCF) approach to fit all cell survival data into the survival model and derive the , , , and values for each cell line. Dependences of these parameters on cell type were thus determined and finally a comprehensive RBE model was derived.
View Article and Find Full Text PDFMed Phys
December 2024
Heidelberg Ion-Beam Therapy Center (HIT), Department of Radiation Oncology, Heidelberg, Germany.
Background: Clinical carbon ion beams offer the potential to overcome hypoxia-induced radioresistance in pancreatic tumors, due to their high dose-averaged Linear Energy Transfer (LETd), as previous studies have linked a minimum LETd within the tumor to improved local control. Current clinical practices at the Heidelberg Ion-Beam Therapy Center (HIT), which use two posterior beams, do not fully exploit the LETd advantage of carbon ions, as the high LETd is primarily focused on the beams' distal edges. Different LETd-boosting strategies, such as Spot-scanning Hadron Arc (SHArc), could enhance LETd distribution by concentrating high-LETd values in potential hypoxic tumor cores while sparing organs at risk.
View Article and Find Full Text PDFJ Hazard Mater
November 2024
RECETOX, Faculty of Science, Masaryk University, Kotlarska 2, 61137 Brno, Czech Republic.
This paper presents an approach to apply aquatic passive sampling (PS) in regulatory chemical water quality monitoring in Europe. Absorption-based passive sampling is well developed and suitable for the sampling of hydrophobic chemicals, some of which are European Water Framework Directive priority substances with Environmental Quality Standards (EQS) derived for biota. Considering a chemical activity approach to chemical risk assessment, we propose equilibrium concentration in lipids (from passive water sampling) as a reference value for measured concentrations in biota.
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