@article{meric_alagoz_hysing_koegler_lathouwers_lionheart_mattingly_obhodas_pausch_pettersen_et al._2023, title={A hybrid multi-particle approach to range assessment-based treatment verification in particle therapy}, volume={13}, ISSN={["2045-2322"]}, DOI={10.1038/s41598-023-33777-w}, abstractNote={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 $${1}\,\hbox {mm}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:mn>1</mml:mn> <mml:mspace /> <mml:mtext>mm</mml:mtext> </mml:mrow> </mml:math> can be detected at relatively low proton intensities ( $$22.30(13)\times 10^{7}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:mn>22.30</mml:mn> <mml:mrow> <mml:mo>(</mml:mo> <mml:mn>13</mml:mn> <mml:mo>)</mml:mo> </mml:mrow> <mml:mo>×</mml:mo> <mml:msup> <mml:mn>10</mml:mn> <mml:mn>7</mml:mn> </mml:msup> </mml:mrow> </mml:math> 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.}, number={1}, journal={SCIENTIFIC REPORTS}, author={Meric, Ilker and Alagoz, Enver B. and Hysing, Liv and Koegler, Toni and Lathouwers, Danny and Lionheart, William R. B. and Mattingly, John and Obhodas, Jasmina and Pausch, Guntram and Pettersen, Helge E. S. N. and et al.}, year={2023}, month={Apr} }
 @article{ytre-hauge_skjerdal_mattingly_meric_2019, title={A Monte Carlo feasibility study for neutron based real-time range verification in proton therapy}, volume={9}, ISSN={["2045-2322"]}, DOI={10.1038/s41598-019-38611-w}, abstractNote={Abstract Uncertainties in the proton range in tissue during proton therapy limit the precision in treatment delivery. These uncertainties result in expanded treatment margins, thereby increasing radiation dose to healthy tissue. Real-time range verification techniques aim to reduce these uncertainties in order to take full advantage of the finite range of the primary protons. In this paper, we propose a novel concept for real-time range verification based on detection of secondary neutrons produced in nuclear interactions during proton therapy. The proposed detector concept is simple; consisting of a hydrogen-rich converter material followed by two charged particle tracking detectors, mimicking a proton recoil telescopic arrangement. Neutrons incident on the converter material are converted into protons through elastic and inelastic (n,p) interactions. The protons are subsequently detected in the tracking detectors. The information on the direction and position of these protons is then utilized in a new reconstruction algorithm to estimate the depth distribution of neutron production by the proton beam, which in turn is correlated with the primary proton range. In this paper, we present the results of a Monte Carlo feasibility study and show that the proposed concept could be used for real-time range verification with millimetric precision in proton therapy.}, journal={SCIENTIFIC REPORTS}, author={Ytre-Hauge, Kristian Smeland and Skjerdal, Kyrre and Mattingly, John and Meric, Ilker}, year={2019}, month={Feb} }
 @article{ytre-hauge_skjerdal_mattingly_meric_2019, title={A Monte Carlo feasibility study for neutron based real-time range verification in proton therapy (vol 170, 09001, 2018)}, volume={9}, ISSN={["2045-2322"]}, DOI={10.1038/s41598-019-49488-0}, abstractNote={An amendment to this paper has been published and can be accessed via a link at the top of the paper.}, journal={SCIENTIFIC REPORTS}, author={Ytre-Hauge, Kristian Smeland and Skjerdal, Kyrre and Mattingly, John and Meric, Ilker}, year={2019}, month={Oct} }
 @article{chang_meric_sudac_nad_obhodas_hou_zhang_gardner_2019, title={Implementation of the Monte Carlo Library Least-Squares (MCLLS) approach for quantification of the chlorine impurity in an on-line crude oil monitoring system}, volume={155}, ISSN={["0969-806X"]}, DOI={10.1016/j.radphyschem.2018.05.012}, abstractNote={Prompt gamma-ray neutron activation analysis (PGNAA) has been widely used for elemental analysis of bulk samples as it provides an on-line, rapid and non-destructive means of performing such analysis. The Monte Carlo Library Least-Squares (MCLLS) approach is one of the methods for quantitative analysis providing elemental weight fractions via an assumption that the total prompt gamma-ray spectrum is a linear combination of the contributions from the individual prompt gamma-ray spectra of the sample constituents. For the generation of prompt gamma-ray libraries of each constituent, a specific purpose Monte Carlo code system called Center for Engineering Applications of Radioisotopes Coincidence Prompt Gamma-Ray (CEARCPG) is utilized. In this work, the focus was on detecting and measuring chlorine impurity in crude oil samples, i.e. trace amounts of chlorine. A preliminary study investigating the feasibility of PGNAA method in conjunction with the MCLLS approach for measuring trace amounts of chlorine in oil samples was performed. For this purpose, an extended version of the MCLLS approach, the so-called MCLLSX approach, was proposed and applied for the quantitative analysis. The results presented in this paper prove the feasibility of the proposed approach.}, journal={RADIATION PHYSICS AND CHEMISTRY}, author={Chang, Hao Ping and Meric, Ilker and Sudac, Davorin and Nad, Karlo and Obhodas, Jasmina and Hou, Guojing and Zhang, Yan and Gardner, Robin P.}, year={2019}, month={Feb}, pages={197–201} }
 @article{chang_meric_sudac_nad_obhodas_gardner_2017, title={Development of a method for on-line determination of chlorine impurity in crude oil by using fast neutrons}, volume={209}, ISSN={["1873-7153"]}, DOI={10.1016/j.fuel.2017.06.123}, abstractNote={An important challenge in the petroleum industry is to reduce the salt content to acceptable levels in crude oil. Continuous monitoring of crude oil salinity is thus an important aspect. However, development of safe and reliable on-line and non-intrusive monitoring systems is still a challenging task. In this work, a method for non-intrusive, on-line monitoring of the chlorine impurity in crude oil based on prompt gamma-ray neutron activation analysis (PGNAA) in conjunction with a portable pulsed neutron generator producing 14 MeV neutrons in deuterium-tritium (DT) nuclear reactions is proposed and tested. Simulations with Monte Carlo N-Particle version 6 (MCNP6) transport code combined with Center for Engineering Applications of Radioisotopes Detector Response Function (CEARDRF) and a specific purpose Monte Carlo code called Center for Engineering Applications of Radioisotopes Coincidence Prompt Gamma-Ray (CEARCPG) were used for the design optimization of the experiments. Preliminary results indicate that a minimum detection limit for chlorine impurity of about 71 mg/L is achievable for an integration time of 30 min.}, journal={FUEL}, author={Chang, Hao Ping and Meric, Ilker and Sudac, Davorin and Nad, Karlo and Obhodas, Jasmina and Gardner, Robin P.}, year={2017}, month={Dec}, pages={643–649} }
 @article{meric_johansen_mattingly_gardner_2014, title={On the ill-conditioning of the multiphase flow measurement by prompt gamma-ray neutron activation analysis}, volume={95}, ISSN={["0969-806X"]}, DOI={10.1016/j.radphyschem.2012.12.047}, abstractNote={Abstract Prompt gamma-ray neutron activation analysis (PGNAA) in conjunction with the so-called Monte Carlo library least-square (MCLLS) approach for the quantitative analysis is currently considered for rapid, non-intrusive and online measurements of multiphase oil/gas/seawater flow. The results of this work indicate that the current method would be feasible for measurements of multiphase flow provided that the ill-conditioning in the MCLLS approach could be treated appropriately.}, journal={RADIATION PHYSICS AND CHEMISTRY}, author={Meric, Ilker and Johansen, Geir A. and Mattingly, J. and Gardner, R. P.}, year={2014}, month={Feb}, pages={401–404} }
 @article{meric_johansen_holstad_calderon_gardner_2012, title={Enhancement of the intrinsic gamma-ray stopping efficiency of Geiger-Muller counters}, volume={696}, ISSN={["0168-9002"]}, DOI={10.1016/j.nima.2012.08.086}, abstractNote={Abstract Geiger–Muller counters are frequently employed in many industrial radiation gauges. However, it is of practical interest to further extend the usage areas of these detectors to include applications such as dual modality densitometry and industrial gamma-ray tomography. This is mainly because these counters exhibit a high degree of robustness in demanding environments, their relatively low cost and the fact that they require simple read-out electronics. The main drawback of these counters is their relatively poor intrinsic gamma-ray stopping efficiency which is of the order of 1.0% for a wide range of primary photon energies. Therefore, identification of a method whereby the poor stopping efficiency in these detectors could be improved is of great interest. For this purpose Monte Carlo analyses were carried out, at photon emission energy of 59.5 keV, to investigate the feasibility of introducing high density and high atomic number insulating disks inside a cylindrical Geiger–Muller counter. Calculations were performed using a specific purpose Monte Carlo code that was validated against experimental stopping efficiency data at 59.5 keV. The preliminary simulation results show that a threefold increase in the efficiency of the counter could be expected as well as the fact that the simulation of secondary electron transport in the fill gas becomes critical. The results reported in this work also show that the maximum achievable low energy gamma-ray detection efficiency in Geiger–Muller counters is still significantly less than the efficiency of semiconductor and scintillation detectors at the corresponding photon energies. Therefore, the development of efficient Geiger–Muller counters will remain a challenge.}, journal={NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT}, author={Meric, Ilker and Johansen, Geir A. and Holstad, Marie B. and Calderon, Adan F. and Gardner, Robin P.}, year={2012}, month={Dec}, pages={46–54} }
 @article{meric_johansen_holstad_mattingly_gardner_2012, title={On the treatment of ill-conditioned cases in the Monte Carlo library least-squares approach for inverse radiation analyzers}, volume={23}, ISSN={["1361-6501"]}, DOI={10.1088/0957-0233/23/5/055603}, abstractNote={Prompt gamma-ray neutron activation analysis (PGNAA) has been and still is one of the major methods of choice for the elemental analysis of various bulk samples. This is mostly due to the fact that PGNAA offers a rapid, non-destructive and on-line means of sample interrogation. The quantitative analysis of the prompt gamma-ray data could, on the other hand, be performed either through the single peak analysis or the so-called Monte Carlo library least-squares (MCLLS) approach, of which the latter has been shown to be more sensitive and more accurate than the former. The MCLLS approach is based on the assumption that the total prompt gamma-ray spectrum of any sample is a linear combination of the contributions from the individual constituents or libraries. This assumption leads to, through the minimization of the chi-square value, a set of linear equations which has to be solved to obtain the library multipliers, a process that involves the inversion of the covariance matrix. The least-squares solution may be extremely uncertain due to the ill-conditioning of the covariance matrix. The covariance matrix will become ill-conditioned whenever, in the subsequent calculations, two or more libraries are highly correlated. The ill-conditioning will also be unavoidable whenever the sample contains trace amounts of certain elements or elements with significantly low thermal neutron capture cross-sections. In this work, a new iterative approach, which can handle the ill-conditioning of the covariance matrix, is proposed and applied to a hydrocarbon multiphase flow problem in which the parameters of interest are the separate amounts of the oil, gas, water and salt phases. The results of the proposed method are also compared with the results obtained through the implementation of a well-known regularization method, the truncated singular value decomposition. Final calculations indicate that the proposed approach would be able to treat ill-conditioned cases appropriately.}, number={5}, journal={MEASUREMENT SCIENCE AND TECHNOLOGY}, author={Meric, Ilker and Johansen, Geir A. and Holstad, Marie B. and Mattingly, John and Gardner, Robin P.}, year={2012}, month={May} }