A deterministic tool for neutron-photon images simulation and fusion

1. A deterministic tool for neutron-photon images simulation and fusion M. Valente(1,2), F. Malano(1,2), P.Pérez(2,3), G. Depaola(2) 1 CONICET, Argentina. 2 Universidad Nacional de Córdoba, Argentina. 3 Agencia Nacional de Promoción Científica y Tecnológica, Argentina. a b Nowadays, computer simulation constitutes a particularly useful experimentation tool for the study and characterization of image quality parameters in several applications. X-ray and neutron radiographies have proved to be efficient techniques for investigations by means of non-destructive techniques as well as being useful for many applications and fundamental research. This work presents novel software devoted to absorption contrast imaging; which is developed in base on a deterministic simulation package along with dedicated image processing subroutines. Volumetric imaging is attained by means of dedicated tomography reconstruction techniques. Originally, the software tool was devoted to X-ray projection imaging according to a completely deterministic approach. However, the versatility derived from the implemented general purpose particle tracking (ray-tracing) allows to perform photon as well as neutron projection radiographies. Neutrons are able to distinguish between different isotopes and neutron radiography is an important tool for different applications, like industrial quality control and studies of radioactive materials. Deterministic imaging system The core of the system is a simple transport mechanism: ray-tracing approach. Sample, beam and detector geometry, properties and location are defined by the user. Radiation transport simulation consists on transmitted flux reaching the detector, based on simple interaction models to provide attenuation relations. Objects geometry defined by means of quadric surfaces allowing also virtual voxelization. Incident beam (photon or neutron) is attenuated by sample and the emerging radiation is detected forming photon/neutron radiography. Detector output: Image representing sample macroscopic structure, according to radiation attenuation: Φ0(i,j,E) and Φ(i,j,E) : incident and emerging fluxes, respectively; μ(i,j,E): material linear attenuation coefficient for photons or total macroscopic neutron cross section for neutrons and L: sample thickness along the (i,j) position. Computation tool validation Benchmarking and preliminary validation: Tests of consistency and comparisons with general purpose Monte Carlo codes: PENELOPE (Salvat et al. 2008) and GEANT4 (Agostinelli et al. 2003). Quantitative comparisons deterministic radiographies vs. MC: BNCT application: 100mm height concentric cylinders, liquid water in outer (100mm diameter) and mixture of liquid water and borax in inner (60mm diameter) irradiated according basic experimental layout of photon/neutron radiography. a b a b c c Fig. 5:Photon (a) and neutron (b) phantom radiographies and central profiles comparisons (c). Fig.2: Parallel (a) and divergent (b) X-ray beam radiographies and central profiles comparisons (c). Fig. 1: Irradiation set up. Fig. 4: GEANT4 runtime shower. a b a b c Fig. 11: 40ppm 10B mixture image from thermal neutron parallel beam by means of GEANT4. Fig. 3: PENELOPE radiography (a) and central profiles comparisons with deterministic model (b). c Fig. 8: 30keV photons (a) and edge filtered thermal neutrons (b) central slices and fusion image (c) by means of the developed toolkit. Fig.7:Tomography by thermal neutrons (a) and X-rays (b) along with central profiles comparisons (c) obtained with deterministic model. Fig. 9: Complete 3D volume reconstruction of 400ppm 10B mixture irradiated with thermal neutrons by means of the developed toolkit. Fig. 10: Patch-type 3D visualization of reconstruced sample (400ppm 10B mixture) irradiated with thermal neutrons by means of the developed toolkit. Abstract & Goals A novel photon and neutron radiographic imaging system is presented. The computation toolkit consists of a main core, devoted to the radiation transport in base of deterministic interaction approach, and dedicated subroutines for image processing and visualization including tomography reconstruction and image fusion. The feasibility and reliability of the proposed method was suitably characterized by means of comparisons with general purpose Monte Carlo techniques, which ensure full radiation transport description. The main goal consists on assessing almost immediately acceptable estimations of photon-neutron transmission images, which may constitute a useful tool for imaging experimentation and research as well as for didactics purposes. Introduction & theoretical background Software benchmarcking & Results Comclusions & Remarks • A novel imaging toolkit has been developed based on deterministic approach to absorption contrast radiography. Performance and reliability for X-ray and neutron radiography has been benchmarked comparing with Monte Carlo full imaging description. Image processing and fusion along with tomography reconstruction algorithms have proved to be useful tool for quantification and experimentation. Noticeable remarks are: • Huge computation reduction: Present toolkit performs image calculation 1 million times faster than typical MC. • Neutron transport required significant more complex treatment than X-ray beams, mainly due to compound cross section models. • The versatility regarding the possibility of introducing suitable scattering approximation models. implementation of this toolkit for different applications and purposes, like research and didactics. • Further efforts are being devoted to wider, deeper and quite case-to-case specific validation of implemented photon/neutron models. In addition, suitable first-order scattering models are being considered in order to improve, at least at first order, the absorption contrast image by means of considering scattering effects. This work has been partially supported by PIP grants and ANPCyT through fellowship founds. For further information, please contact: valente@famaf.unc.edu.ar or visit www.famaf.unc.edu.ar/~valente.