R. Barbuzza

Industrial applications of plasma focus radiation

Applications of a small-chamber Plasma Focus used as portable radiation generator is presented. The device was designed to maximize the fluence. The mean neutron yield was 3 x 108 neutrons of 2.45 MeV per shot, corresponding to a 106 neutrons/cm2 fluence on the external surface of the chamber. A technique to detect the presence of water in the neighborhood of a compact Plasma Focus is presented. The measuring system is composed by two neutron detectors operated simultaneously on every shot. The first detector is used to register the PF neutron yield in each shot; whereas the other one was designed for detecting neutrons scattered by the blanket. The results indicate that the system is able to detect water contents of few percents in volume. The correlation of the counts recorded by thedetectors located at different positions was mapped with the water distribution around the neutron source. The complete detecting system is very simple and inexpensive. Among many other potential applications, the technique is specially suited for soil humidity prospection. X rays radiation emitted by the compact Plasma Focus operated in Deuterium has been used for introspective radiographic imaging of metallic objects. The samples were located about 1 m away from the PF chamber wall. High-sensitivity, fast-response commercial radiographic film was used as x-ray detector. A set of experimental images is presented demonstrating a very high penetration power of the x-ray beam. Among many other applications, the presented technique is specially suited for introspective visualization of pieces manufactured on metal. Radiographic projections of a stainless steel BNC elbow taken at 8 different angles were processed to reconstruct transversal cuts of the piece. A computer technique for 3D reconstructions was combined with radiographic images of objects X-rayed with a compact plasma focus. The technique is able to automatically determine the position of the rotation axis, reconstruct the 3D-attenuation map, and display inner cuts. The system was demonstrated in introspective tomographic imaging of a stainless steel BNC elbow.

Using a 4.7 kJ Plasma Focus for introspective imaging of metallic objects and for neutronic detection of water

A compact Plasma Focus operated in Deuterium has been used as a pulsed radiation source for two different applications: x-ray introspective imaging of metallic objects and water detection by elastic neutron scattering. The samples for radiographic imaging were located outside the PF chamber, about 1 m away from the chamber wall. High-sensitivity, fast-response commercial radiographic film was used as x-ray detector. Experimental images are presented demonstrating a very high penetration power of the x-ray beam. Among many other applications, the presented technique is specially suited for ultrafast introspective visualization of pieces manufactured on metal. Regarding to the second application, a method to detect the presence of water in the neighborhood of a compact Plasma Focus is presented. The measuring system is composed by two silver activation detectors operated simultaneously on every shot. The first detector is used to register the PF neutron yield; whereas the other one is used to detect neutron...

Tomographic reconstruction using heuristic Monte Carlo methods

Abstract A tomographic reconstruction method based on Monte Carlo random searching guided by the information contained in the projections of radiographed objects is presented. In order to solve the optimization problem, a multiscale algorithm is proposed to reduce computation. The reconstruction is performed in a coarse-to-fine multigrid scale that initializes each resolution level with the reconstruction of the previous coarser level, which substantially improves the performance. The method was applied to a real case reconstructing the internal structure of a small metallic object with internal components, showing excellent results.

Efficient scatter model for simulation of ultrasound images from computed tomography data

Background and motivation: Real-time ultrasound simulation refers to the process of computationally creating fully synthetic ultrasound images instantly. Due to the high value of specialized low cost training for healthcare professionals, there is a growing interest in the use of this technology and the development of high fidelity systems that simulate the acquisitions of echographic images. The objective is to create an efficient and reproducible simulator that can run either on notebooks or desktops using low cost devices. Materials and methods: We present an interactive ultrasound simulator based on CT data. This simulator is based on ray-casting and provides real-time interaction capabilities. The simulation of scattering that is coherent with the transducer position in real time is also introduced. Such noise is produced using a simplified model of multiplicative noise and convolution with point spread functions (PSF) tailored for this purpose. Results: The computational efficiency of scattering maps generation was revised with an improved performance. This allowed a more efficient simulation of coherent scattering in the synthetic echographic images while providing highly realistic result. We describe some quality and performance metrics to validate these results, where a performance of up to 55fps was achieved. Conclusion: The proposed technique for real-time scattering modeling provides realistic yet computationally efficient scatter distributions. The error between the original image and the simulated scattering image was compared for the proposed method and the state-of-the-art, showing negligible differences in its distribution.