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Your search keyword '"Georg, Dietmar"' showing total 33 results
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33 results on '"Georg, Dietmar"'

1. Roadmap: helium ion therapy

Author

Mairani, Andrea, primary, Mein, Stewart, additional, Blakely, Eleanor, additional, Debus, Jürgen, additional, Durante, Marco, additional, Ferrari, Alfredo, additional, Fuchs, Hermann, additional, Georg, Dietmar, additional, Grosshans, David R, additional, Guan, Fada, additional, Haberer, Thomas, additional, Harrabi, Semi, additional, Horst, Felix, additional, Inaniwa, Taku, additional, Karger, Christian P, additional, Mohan, Radhe, additional, Paganetti, Harald, additional, Parodi, Katia, additional, Sala, Paola, additional, Schuy, Christoph, additional, Tessonnier, Thomas, additional, Titt, Uwe, additional, and Weber, Ulrich, additional

Published
2022
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12. Advanced Radiation DOSimetry phantom (ARDOS): a versatile breathing phantom for 4D radiation therapy and medical imaging

Author

Kostiukhina, Natalia, primary, Georg, Dietmar, additional, Rollet, Sofia, additional, Kuess, Peter, additional, Sipaj, Andrej, additional, Andrzejewski, Piotr, additional, Furtado, Hugo, additional, Rausch, Ivo, additional, Lechner, Wolfgang, additional, Steiner, Elisabeth, additional, Kertész, Hunor, additional, and Knäusl, Barbara, additional

Published
2017
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31. Benchmarking GATE/Geant4 for 16 O ion beam therapy.

Author

Resch AF, Fuchs H, and Georg D

Subjects
Humans, Linear Energy Transfer, Relative Biological Effectiveness, Benchmarking, Monte Carlo Method, Oxygen Radioisotopes therapeutic use
Abstract

Oxygen ([Formula: see text]) ions are a potential alternative to carbon ions in ion beam therapy. Their enhanced linear energy transfer indicates a higher relative biological effectiveness and a reduced oxygen enhancement ratio. Due to the limited availability of [Formula: see text] ion beams, Monte Carlo (MC) transport codes are important research tools for investigating their potential. The purpose of this study was to validate GATE/Geant4 for [Formula: see text] ion beam therapy using experimental data from literature. Five hadron physics lists and two electromagnetic options were benchmarked against measured depth dose distributions (DDDs) and charge-changing cross sections. The simulated beam ranges deviated by less than 0.5% for all physics configurations and only a few points exceeded the gamma index criterion (2%/1 mm). However, the simulated partial charge-changing cross sections deviated considerably for some hadron physics configurations. Best agreement with the experimental values was obtained with the quantum molecular dynamics model (QMD), and we therefore suggest using this model in Geant4 to accurately describe the fragmentation of [Formula: see text] ion beams into lighter fragments ([Formula: see text]).

Published
2017
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32. Interpretation and evaluation of the gamma index and the gamma index angle for the verification of IMRT hybrid plans.

Author

Stock M, Kroupa B, and Georg D

Subjects
Algorithms, Gamma Rays, Humans, Models, Statistical, Phantoms, Imaging, Photons, Radiometry, Radiotherapy Dosage, X-Ray Film, Film Dosimetry methods, Radiotherapy Planning, Computer-Assisted methods, Radiotherapy, Conformal methods
Abstract

In IMRT, the method for a quantitative comparison of two-dimensional dose distributions is still under development. The gamma evaluation method proposed by Low et al is the most accepted approach and has been adapted by many groups. Based on the concept of Low et al we developed a software tool with an intelligent search algorithm to minimize the calculation time. For the interpretation of deviations a y angle distribution and other tools (dose difference map, profiles, y area histograms, etc) are integrated in the software package. Ten hybrid plans are included in the verification study containing 6 IMRT head and neck cases, 2 IMRT prostate cases and one IMRT paravertebral case as well as a standard uniform intensity conformal 4 field box treatment for comparison. IMRT plans are realized with a segmental MLC delivery technique. The fields of a hybrid plan are applied at once and dose distributions are measured with films in three planes of a verification phantom. All y vector calculations are based on a 3% dose criterion and a 3 mm DTA acceptance criterion. The mean value gamma(mean) (mean value in the y distribution) of the various IMRT plans is 0.45+/-0.10 (1 SD). On average, the percentage of points exceeding the acceptance criteria of gamma < or = 1 (gamma > 1) is 5.8+/-5.4% (1 SD). The mean value of gamma 1% (1% of points have an equal or higher gamma value) is 1.47+/-0.59 (1 SD) for IMRT plans. In 5 out of 27 planes, gamma > 1 is substantially larger than the average. This is also indicated in gamma area histograms. Planes with large areas outside the tolerance criteria were further evaluated using gamma angle distributions. This additional information indicates that the large areas with high gamma values are dominated by the dose difference. It is shown that the deviations are influenced by tongue and groove effects. From the statistical evaluation of gamma values (e.g. gamma area histogram), acceptance criteria for IMRT hybrid plans can be defined. For the interpretation of the gamma maps, distributions of the gamma angle and traditional evaluation methods, such as dose profiles, are still very useful.

Published
2005
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33. Application of commercial MOSFET detectors for in vivo dosimetry in the therapeutic x-ray range from 80 kV to 250 kV.

Author

Ehringfeld C, Schmid S, Poljanc K, Kirisits C, Aiginger H, and Georg D

Subjects
Equipment Design, Equipment Failure Analysis, Pilot Projects, Radiotherapy, Radiotherapy Planning, Computer-Assisted methods, Radiotherapy, Computer-Assisted methods, Reproducibility of Results, Sensitivity and Specificity, Transistors, Electronic, X-Ray Therapy methods, Radiometry instrumentation, Radiotherapy Planning, Computer-Assisted instrumentation, Radiotherapy, Computer-Assisted instrumentation, Transducers, X-Ray Therapy instrumentation
Abstract

The purpose of this study was to investigate the dosimetric characteristics (energy dependence, linearity, fading, reproducibility, etc) of MOSFET detectors for in vivo dosimetry in the kV x-ray range. The experience of MOSFET in vivo dosimetry in a pre-clinical study using the Alderson phantom and in clinical practice is also reported. All measurements were performed with a Gulmay D3300 kV unit and TN-502RDI MOSFET detectors. For the determination of correction factors different solid phantoms and a calibrated Farmer-type chamber were used. The MOSFET signal was linear with applied dose in the range from 0.2 to 2 Gy for all energies. Due to fading it is recommended to read the MOSFET signal during the first 15 min after irradiation. For long time intervals between irradiation and readout the fading can vary largely with the detector. The temperature dependence of the detector signal was small (0.3% degrees C(-1)) in the temperature range between 22 and 40 degrees C. The variation of the measuring signal with beam incidence amounts to +/-5% and should be considered in clinical applications. Finally, for entrance dose measurements energy-dependent calibration factors, correction factors for field size and irradiated cable length were applied. The overall accuracy, for all measurements, was dominated by reproducibility as a function of applied dose. During the pre-clinical in vivo study, the agreement between MOSFET and TLD measurements was well within 3%. The results of MOSFET measurements, to determine the dosimetric characteristics as well as clinical applications, showed that MOSFET detectors are suitable for in vivo dosimetry in the kV range. However, some energy-dependent dosimetry effects need to be considered and corrected for. Due to reproducibility effects at low dose levels accurate in vivo measurements are only possible if the applied dose is equal to or larger than 2 Gy.

Published
2005
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