faycal kharfi
Setif1 university, Physics, Faculty Member
Neutron imaging is a powerful method for non-destructive investigations where high penetration through metals and in particular high contrast for hydrogenous materials maybe exploited. Due to the complexity of digital neutron static or... more
Neutron imaging is a powerful method for non-destructive investigations where high penetration through metals and in particular high contrast for hydrogenous materials maybe exploited. Due to the complexity of digital neutron static or video image formation, image capture conditions and parameters must be accurately selected. In this work, implementation of a new neutron imaging system based on CCD camera and LiF-ZnS scintillator is presented. The image characteristics in terms of contrast, noise and dynamic range and investigation limits of this new imaging system were studied as a function of the neutron source properties.
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An ideal neutron radiograph, for quantification and 3D tomographic image reconstruction, should be a transmission image which exactly obeys to the exponential attenuation law of a monochromatic neutron beam. There are many reasons for... more
An ideal neutron radiograph, for quantification and 3D tomographic image reconstruction, should be a transmission image which exactly obeys to the exponential attenuation law of a monochromatic neutron beam. There are many reasons for which this assumption does not hold for high neutron absorbing materials. The main deviations from the ideal are due essentially to neutron beam hardening effect. The main challenges of this work are the characterization of neutron transmission through boron enriched steel materials and the observation of beam hardening. Then, in our work, the influence of beam hardening effect on neutron tomographic image, for samples based on these materials, is studied. MCNP and FBP simulation are performed to adjust linear attenuation coefficients data and to perform 2D tomographic image reconstruction with and without beam hardening corrections. A beam hardening correction procedure is developed and applied based on qualitative and quantitative analyses of the projections data. Results from original and corrected 2D reconstructed images obtained shows the efficiency of the proposed correction procedure.
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Neutron imaging is a powerful method for non-destructive investigations where high penetration through metals and in particular high contrast for hydrogenous materials maybe exploited. Due to the complexity of digital neutron static or... more
Neutron imaging is a powerful method for non-destructive investigations where high penetration through metals and in particular high contrast for hydrogenous materials maybe exploited. Due to the complexity of digital neutron static or video image formation, image capture conditions and parameters must be accurately selected. In this work, implementation of a new neutron imaging system based on CCD camera and LiF-ZnS scintillator is presented. The image characteristics in terms of contrast, noise and dynamic range and investigation limits of this new imaging system were studied as a function of the neutron source properties.
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ABSTRACT The characterization of neutron absorbing materials as well as quantification of neutron attenuation through matter is very essential in various fields, namely in shielding calculation. The objective of this work is to describe... more
ABSTRACT The characterization of neutron absorbing materials as well as quantification of neutron attenuation through matter is very essential in various fields, namely in shielding calculation. The objective of this work is to describe an experimental procedure to be used for the determination of neutron transmission through different materials. The proposed method is based on the relation between the gray value measured on neutron radiography image and the corresponding inducing neutron beam. For such a purpose, three kinds of materials (in shape of plate) were investigated using thermal neutrons: (1) boron-alloyed stainless steel as strong absorber; (2) copper and steel as fair absorbers and (3) aluminum as weak absorber. This work is not limited to the determination of neutron transmission through matters; it is also spread out to the measure of the surface density of the neutron absorbing elements (ρs) as a function of thickness of neutron absorbing material such as boron-alloyed stainless steel. The beam hardening effect depending on material thickness was also studied using the neutron transmission measurements. A theoretical approach was used to interpret the experimental results. The neutron transmission measurements were performed at the Neutron Radiography and Tomography facility of the Atomic Institute of the Austrian Universities in Vienna. Finally, a Maxwellian neutron distribution of incident neutron beam was used in the theoretical calculations of neutron energy shift in order to compare with experiments results. The obtained experimental results are in a good agreement with the developed theoretical approach.
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In hadrontherapy, oxygen ions 16O can be currently considered as an alternative to carbon ions 12C designed specifically for the treatment of deep and radioresistant tumors. Secondary particles, particularly neutrons constitute a serious... more
In hadrontherapy, oxygen ions 16O can be currently considered as an alternative to carbon ions 12C designed specifically for the treatment of deep and radioresistant tumors. Secondary particles, particularly neutrons constitute a serious problem of undesirable additional irradiation to surrounding healthy tissue. The objective of this study is to evaluate, by Monte-Carlo simulation [code Particle and Heavy Ion Transport code System (PHITS)], the contribution in terms of dose of secondary neutrons produced during interaction 16O ion of 300 MeV u−1 in a soft tissue phantom. The dose of 16O ion, secondary particles and neutrons is evaluated, as well as the particle fluence and energy spectra of neutrons. The contribution to the total dose of secondary neutrons in a soft tissue phantom represents 0.1%. This dose, although apparently insignificant, is essential to conduct even more in-depth studies to understand the long-term effects of these secondary neutrons on the patient’s body espe...
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Spatial resolution limit is a very important parameter of an imaging system that should be taken into consideration before examination of any object. The objectives of this work are the determination of a neutron imaging system's... more
Spatial resolution limit is a very important parameter of an imaging system that should be taken into consideration before examination of any object. The objectives of this work are the determination of a neutron imaging system's response in terms of spatial resolution. The proposed procedure is based on establishment of the Modulation Transfer Function (MTF). The imaging system being studied is based on a high sensitivity CCD neutron camera (2×10(-5)lx at f1.4). The neutron beam used is from the horizontal beam port (H.6) of the Algerian Es-Salam research reactor. Our contribution is on the MTF determination by proposing an accurate edge identification method and a line spread function undersampling problem-resolving procedure. These methods and procedure are integrated into a MatLab code. The methods, procedures and approaches proposed in this work are available for any other neutron imaging system and allow for judging the ability of a neutron imaging system to produce spatial (internal details) properties of any object under examination.
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During the last three years a static neutron radiography facility has been designed and installed around one of the horizontal neutron beam channels of the Es-Salam research reactor. In order to extend the field of application of neutron... more
During the last three years a static neutron radiography facility has been designed and installed around one of the horizontal neutron beam channels of the Es-Salam research reactor. In order to extend the field of application of neutron radiography, a development ...
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Hadron radiation therapy is of great interest worldwide. Heavy-ion beams provide ideal therapeutic conditions for deep-seated local tumours. At the Heidelberg Ion Beam Therapy Center (HIT, Germany), protons and carbon ions are already... more
Hadron radiation therapy is of great interest worldwide. Heavy-ion beams provide ideal therapeutic conditions for deep-seated local tumours. At the Heidelberg Ion Beam Therapy Center (HIT, Germany), protons and carbon ions are already integrated into the clinical routine, while 16O ions are still used for research only. To ensure the protection of the technical staff and members of the public, it is required to estimate the neutron dose distribution for optimal working conditions and at different locations. The Particle and Heavy Ion Transport Code System (PHITS) is used in this work to evaluate the dose rate distribution of secondary neutrons in a treatment room at HIT where 16O ions are used: an equivalent target in soft tissue is considered in the shielding assessment to simulate the interaction of the beam with patients. The angular dependence of neutron fluences and energy spectra around the considered phantom were calculated. Alongside the spatial distribution of the neutron a...
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Introduction: Oxygen (16O) ion beams have been recommended for cancer treatment due to its physical Bragg curve feature and biological property. The goal of this research is to use Monte Carlo simulation to analyze the physical features... more
Introduction: Oxygen (16O) ion beams have been recommended for cancer treatment due to its physical Bragg curve feature and biological property. The goal of this research is to use Monte Carlo simulation to analyze the physical features of the 16O Bragg curve in water and tissue. Material and methods: In order to determine the benefits and drawbacks of ion beam therapy, Monte Carlo simulation (PHITS code) was used to investigate the interaction and dose deposition properties of oxygen ions beam in water and human tissue medium. A benchmark study for the depth–dose distribution of a 16O ion beam in a water phantom was established using the PHITS code. Bragg’s peak location of 16O ions in water was simulated using the effect of water’s mean ionization potential. The contribution of secondary particles produced by nuclear fragmentation to the total dose has been calculated. The depth and radial dose profiles of 16O, 12C, 4He, and 1H beams were compared. Results: It was shown that PHITS...
Introduction: In this work, a dosimetric comparison between the already used 3D conformal radiattion therapy (3D-CRT) and the recently implemented intensity modulation radiation therapy (IMRT) techniques was performed in irradiation of... more
Introduction: In this work, a dosimetric comparison between the already used 3D conformal radiattion therapy (3D-CRT) and the recently implemented intensity modulation radiation therapy (IMRT) techniques was performed in irradiation of lung cancer. Delivered doses were compared in terms of conformity of target coverage, organ at risks (OARs) sparing and heterogeniety correction. Materials and Methods: Depth point doses were compared as calculated by the Varian Eclipse treatment planning system (TPS) and experimentally measured by thermoluminescence (TL) dosimetry. Point doses were measured using an original procedure based on the creation of virtual patient with a realistic cancer case. The same lesion of the real case with different volumes and structures contouring details were created on Rando anthropomorphic phantom CT data. The new CT data were then used as an input for the treatment planning by the TPS after performing the necessary adjustments and CT data matching. Dose measu...
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Background: In this study, computed tomography/magnetic resonance imaging (CT/MRI) image registration and fusion in the 3D conformal radiotherapy treatment planning of Glioblastoma brain tumor was investigated. Good CT/MRI image... more
Background: In this study, computed tomography/magnetic resonance imaging (CT/MRI) image registration and fusion in the 3D conformal radiotherapy treatment planning of Glioblastoma brain tumor was investigated. Good CT/MRI image registration and fusion made a great impact on dose calculation and treatment planning accuracy. Indeed, the uncertainly associated with the registration and fusion methods must be well verified and communicated. Unfortunately, there is no standard procedure or mathematical formalism to perform this verification due to noise, distortion, and complicated anatomical situations. Objectives: This study aimed at assessing the effective contribution of MRI in Glioma radiotherapy treatment by improving the localization of target volumes and organs at risk (OARs). It is also a question to provide clinicians with some suitable metrics to evaluate the CT/MRI image registration and fusion results. Methods: Quantitative image registration and fusion evaluation were used...