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5 results on '"Toni Kögler"'

1. Hybrid treatment verification based on prompt gamma rays and fast neutrons: multivariate modelling for proton range determination

Author

Sonja M. Schellhammer, Ilker Meric, Steffen Löck, and Toni Kögler

Subjects
proton therapy, treatment verification, prompt gamma ray, fast neutron, machine learning, multivariate modelling, Physics, QC1-999
Abstract

Robust and fast in vivo treatment verification is expected to increase the clinical efficacy of proton therapy. The combined detection of prompt gamma rays and neutrons has recently been proposed for this purpose and shown to increase the monitoring accuracy. However, the potential of this technique is not fully exploited yet since the proton range reconstruction relies only on a simple landmark of the particle production distributions. Here, we apply machine learning based feature selection and multivariate modelling to improve the range reconstruction accuracy of the system in an exemplary lung cancer case in silico. We show that the mean reconstruction error of this technique is reduced by 30%–50% to a root mean squared error per spot of 0.4, 1.0, and 1.9 mm for pencil beam scanning spot intensities of 108, 107, and 106 initial protons, respectively. The best model performance is reached when combining distribution features of both gamma rays and neutrons. This confirms the advantage of hybrid gamma/neutron imaging over a single-particle approach in the presented setup and increases the potential of this system to be applied clinically for proton therapy treatment verification.

Published
2023
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2. A hybrid multi-particle approach to range assessment-based treatment verification in particle therapy

Author

Ilker Meric, Enver Alagoz, Liv B. Hysing, Toni Kögler, Danny Lathouwers, William R. B. Lionheart, John Mattingly, Jasmina Obhodas, Guntram Pausch, Helge E. S. Pettersen, Hunter N. Ratliff, Marta Rovituso, Sonja M. Schellhammer, Lena M. Setterdahl, Kyrre Skjerdal, Edmond Sterpin, Davorin Sudac, Joseph A. Turko, Kristian S. Ytre-Hauge, and The NOVO collaboration

Subjects
Medicine, Science
Abstract

Abstract Particle therapy (PT) used for cancer treatment can spare healthy tissue and reduce treatment toxicity. However, full exploitation of the dosimetric advantages of PT is not yet possible due to range uncertainties, warranting development of range-monitoring techniques. This study proposes a novel range-monitoring technique introducing the yet unexplored concept of simultaneous detection and imaging of fast neutrons and prompt-gamma rays produced in beam-tissue interactions. A quasi-monolithic organic detector array is proposed, and its feasibility for detecting range shifts in the context of proton therapy is explored through Monte Carlo simulations of realistic patient models and detector resolution effects. The results indicate that range shifts of $${1}\,\hbox {mm}$$ 1 mm can be detected at relatively low proton intensities ( $$22.30(13)\times 10^{7}$$ 22.30 ( 13 ) × 10 7 protons/spot) when spatial information obtained through imaging of both particle species are used simultaneously. This study lays the foundation for multi-particle detection and imaging systems in the context of range verification in PT.

Published
2023
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3. Multivariate statistical modelling to improve particle treatment verification: Implications for prompt gamma-ray timing

Author

Sonja M. Schellhammer, Julia Wiedkamp, Steffen Löck, and Toni Kögler

Subjects
proton therapy, treatment verification, prompt gamma-ray timing, machine learning, multivariate modelling, Physics, QC1-999
Abstract

We present an improved method for in-vivo proton range verification by prompt gamma-ray timing based on multivariate statistical modelling. To this end, prompt gamma-ray timing distributions acquired during pencil beam irradiation of an acrylic glass phantom with air cavities of different thicknesses were analysed. Relevant distribution features were chosen using forward variable selection and the Least Absolute Shrinkage and Selection Operator (LASSO) from a feature assortment based on recommendations of the Image Biomarker Standardisation Initiative. Candidate models were defined by multivariate linear regression and evaluated based on their coefficient of determination R2 and root mean square error RMSE. The newly developed models showed a clearly improved predictive power (R2 > 0.7) compared to the previously used models (R2 < 0.5) and allowed for the identification of introduced air cavities in a scanned treatment field. These results demonstrate that elaborate statistical models can enhance prompt gamma-ray based treatment verification and increase its potential for routine clinical application.

Published
2022
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4. A hybrid multi-particle approach to range assessment-based treatment verification in particle therapy

Author

Ilker Meric, Enver Alagoz, Liv Hysing, Toni Kögler, Danny Lathouwers, William Lionheart, John Mattingly, Jasmina Obhodas, Guntram Pausch, Helge Pettersen, Hunter Ratliff, Marta Rovituso, Sonja Schellhammer, Lena Setterdahl, Kyrre Skjerdal, Edmond Sterpin, Davorin Sudac, Joseph Turko, and Kristian Ytre-Hauge

Subjects
Multidisciplinary Sciences, treatment verification, Science & Technology, PROTON THERAPY, particle therapy, three dimensional imaging, Science & Technology - Other Topics, fast neutrons, CAMERA, prompt gamma rays, EMISSION, PROMPT
Abstract

Particle therapy (PT) used for cancer treatment can spare healthy tissue and reduce treatment toxicity. However, full exploitation of the dosimetric advantages of PT is not yet possible due to range uncertainties, warranting development of range-monitoring techniques. This study proposes a novel range-monitoring technique introducing the yet unexplored concept of simultaneous detection and imaging of fast neutrons and prompt-gamma rays produced in beam-tissue interactions. A quasi-monolithic organic detector array is proposed, and its feasibility for detecting range shifts in the context of proton therapy is explored through Monte Carlo simulations of realistic patient models and detector resolution effects. The results indicate that range shifts of [Formula: see text] can be detected at relatively low proton intensities ([Formula: see text] protons/spot) when spatial information obtained through imaging of both particle species are used simultaneously. This study lays the foundation for multi-particle detection and imaging systems in the context of range verification in PT. ispartof: SCIENTIFIC REPORTS vol:13 issue:1 ispartof: location:England status: published

Published
2022

5. Pulsformdiskrimination und Lichtausbeutemessungen von LAB-basierten Flüssigszintillatoren

Author

Toni Kögler, Junghans, Arnd Rudolf, Zuber, Kai, Cowan, Thomas, and Technische Universität Dresden

Subjects
Physics::Instrumentation and Detectors, digital signal processing, liquid scintillators, ddc:530, digital pulse shape discrimination, Compton spectrometer, digitale Signalverarbeitung, Lichtausbeutemessung, Flüssigszintillator, lineares Alkylbenzen, Compton-Spektrometer, digitale Pulsformdiskriminierung, digital signal processing, light yield of liquid scintillators, linear alkyl benzene, compton spectrometer, digital pulse-shape discrimination
Abstract

Die Grundlage vieler zukünftiger Flüssigszintillator-Neutrinoexperimente (SNO+, Daya Bay, LENA) ist das Lösungsmittel Lineare-Alkyl-Benzene (LAB, C6H5CnH2n+1, n = 10 - 13). Zusammen mit dem weit verbreiteten Szintillator 2,5-Diphenyloxazole (PPO) ist es ein farb- und geruchsloses Detektormaterial mit hohem Flammpunkt. Im Vergleich zu toluol- oder xylolbasierten Szintillatoren ist LAB+PPO preiswert und nicht gesundheitsschädlich. Die Eigenschaften von LAB machen es ebenfalls interessant für die Anwendung an nELBE, die Neutronenfugzeitanlage im Helmholtz-Zentrum Dresden - Rossendorf. Ein neuer Ansatz zur Bestimmung der Lichtausbeute im niederenergetischen Bereich (bis 2 MeV) wird vorgestellt. Kombiniert wurden Messungen mit (quasi) monoenergetischen Gammastrahlungs-Prüfstrahlern und einem in dieser Arbeit aufgebauten Compton-Spektrometer. Letzteres ermöglicht die Bestimmung der Lichtausbeute bis zu 5 keVee. Der Birks-Parameter wurde für eine Lösung von LAB + 3 g/l PPO sowie für den Flüssigszintillator NE-213 bestimmt. Die relative Lichtausbeute in Bezug auf letzteren konnte mit diesen Messmethoden ebenfalls ermittelt werden. Zur spektralen Analyse des Lumineszenzlichtes wurden Messungen an Fluoreszenz- und UV/VIS- Spektrometern durchgeführt. Die Pulsformdiskriminationsfähigkeit auf LAB basierenden Szintillatoren wurde während eines Flugzeitexperiments in einem gemischten n-gamma-Feld eines Cf(252)-Prüfstrahlers ermittelt. Dabei kamen unterschiedliche Algorithmen der semi-analogen und digitalen Pulsformdiskrimination zum Einsatz. Linear alkyl benzene (LAB, C6H5CnH2n+1, n = 10 - 13) is the proposed solvent for the SNO+, the Daya Bay Neutrino and LENA experiment. In solution with the commonly used scintillator PPO it is a colourless, odourless and cheap liquid scintillator with a high fash point and low health hazard compared to toluene based ones. The properties of LAB make this scintillator interesting also for nELBE, the neutron time-of-fight facility at Helmholtz-Zentrum Dresden - Rossendorf. A new approach to measure the light yield in the low-energy range using a combination of quasi-monoenergetic photon sources and a Compton-spectrometer is described. The latter allows the measurement of the light yield down to 5 keVee (electron equivalent). The Birks- Parameter was determined for a homemade solution (LAB + 3 g/l PPO) and for NE-213. The light yield (relative to this standard scintillator) was confrmed by measurements using a fuorescence spectrometer. The ability of pulse-shape-discrimination in a mixed n-gamma- field of a Cf(252) source was tested using different digital and semi-analogue techniques.

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