Computer aided surgery is by sure a set of technologies that provide a real support to surgeons during their operational
job. This includes - but it is not limited to - novel sensors and systems and software for data analysis and visualization.
In particular the use of intraoperational probes is eased if the position of the probe within the operational field can be
exactly calculated by the supporting software. Commercial systems have already been developed for this purpose but
their complexity and cost reduces their usability for the majority of probes. This paper presents a simple approach to
calculate the probe position within the operational field that requires a minimum cost.
Satellite imaging is undergoing a dramatic growth in the last few years. Previously, remote sensing satellites were primarily for scientific or military use. Increasingly, the images obtained by remote sensing satellites are being used by commercial end users. As part of this trend, more remote sensing commercial satellite companies are emerging. Some remote sensing satellites are being developed for commercial purposes, while large distributors are either launching their own remote sensing satellites or marketing satellite imagery for a plethora of end users. This increased interest is due to the large number of forecasted applications offered by civil remote sensing, which may be of interest to sector such as telecommunications, building and public works, agriculture and fishing, environmental and civil protection and risk assessment, management and extraction of natural sources, geology and many others. As a result of a cooperative ESPRIT project co-funded by the European Commission, our company is developing a package based on a hardware implementation of the JBIG algorithm. This algorithm has been chosen for its intriguing characteristics due to its standard and flexible nature. The algorithm allows very good compression ratio when compared to other current codes and fastness is ensured by the hardware implementation.
Neutron imagin techniques are known since a long time as a possible tool for non-destructive testings. However, they found a reduced number of applications out of the inspection of the nuclear fuel so that their diffusion was limited to some centers. This is particularly true in Europe because industries and the army are not used to carry out extensive programs for R and D in the field of NDT. A new European- wide cooperative action was agreed in order to solve this problem. This action is currently running under the COST framework of the European Commission and is comprised of excellence universities, nuclear centers and industries from 10 European countries. Main purpose of this action is the application of neutron imaging - non limiting to transmission radiography and tomography - to the development of advanced materials to be used in the fields of aerospace, civil engineering and mechanics. The initial cumulative results of this action will be presented; furthermore the possibilities for future enlargement of this activity to other European and non-European countries will be explained as well.
In recent years, room temperature semiconductor detectors like CdTe and CdZnTe have been proposed for several scientific, industrial and medical applications. In some cases, these applications require the capability to operate for a long time in intense, sometimes mixed, radiation fields while retaining full spectroscopic performances. In spite of its importance, a detailed characterization of the effects of the radiation damage has not been competed yet for these materials. However, preliminary results carried out by irradiating CdTe detectors with 60Co gamma rays demonstrated that the fatal photon dose is on the order of some tens of thousands Gy, while the detectors are rather insensitive to doses up to few thousands Gy. A wider activity is now being performed by the authors studying both the CdTe and the CdZnTe when involving several types of irradiating sources and different techniques to quantify the induced damaging. This includes the detailed quantitative analysis of retained spectroscopic performances at low and medium energies, the measurement of the dark current and the characterization of the defects and modifications induced in the structure of the crystal by the irradiation process.
The large size is a typical feature of earth observation images. The increasing number of bands simultaneously available on satellites and the launch of system able to achieve a ground resolution as low as one meter is making this problem more a nd more hot. Indeed, the large size of typical images dramatically reduces the possibility to distribute them to a wide number of interest parties. In the wide majority of cases, this problem is currently tackled either by using lossy compression schemes such as basic versions of JPEG or by narrowing the ground extension of the pictures. Of course, both of them are unsatisfactory. Indeed, the partial loss of data may be acceptable only for non-quantitative analysis while narrower pictures may not carry all the needed informant. An alternate possibility is the use of an efficient lossless algorithm. Among others, JBIG has been preferred for this purpose because it achieves very high compression rate, overperforming the well known ZIP algorithm in the wide majority of cases. Further advantages are due to its progressive nature and to its availability as an ITU international standard. In order to have a very performant syste, this algorithm has been implemented by the development of an application specific integrated circuit designed to compress/decompress large volumes of data with throughput rate greater than 1 Gb/min. The performances achieved by the system when dealing with typical visual and radar satellite images and the perspective applications are described.
The use of conventional glass scintillators for x-ray imaging has been limited by the need of a severe trade-off between the detection efficiency of glasses, that is low if the incoming energy exceeds about one hundred keV for conventional glasses, and the achievable spatial resolution, that is greatly affected if the thickness of the glass is increased above 2 mm. Scintillating fiber optic detectors solve this problem thanks to their light guidance properties. A set of different scintillating fiber optic plates (SFOP) has been produced to optimally detect both low (up to 50 kVp) and high (up to some hundreds kVp) energy x-rays. These detectors are coupled to a fiber optic taper which drives the light to a CCD camera through a MCP image intensifier. Alternatively, a focusing lens is employed. The detectors have been used for image acquisitions for digital radiography in the medical field (particularly at the lower energies) and for nondestructive testings, with a particular interest for the preservation of the cultural heritage.
Among neutron imaging techniques, computed tomography represents the most powerful fool when an accurate 2D mapping of the internal structure of an object is desired. In order to exploit the capabilities of this technique, it is necessary to develop a detection system able to acquire the required projections with an enhanced spatial resolution and sensitivity. This could be achieved by the use of novel CCD sensors, but they are not yet available in commercial cameras. Thus, a modular system for the readout of CCD sensors was constructed allowing a fast data acquisition and a simple camera that could be easily upgraded by simply replacing the active sensor has been built. The entire system was used to acquire projections for neutron computed tomography, offering good performance spatial resolution and data transfer rate. A numerical evaluation of system performance when performing NCT is given by the analysis of sample objects.
In the recent years it has been demonstrated that computed tomography represents the most advanced imaging technique in the field of non-destructive testings. In this field, although x-ray based facilities still play a dominant role, neutron tomography can provide very good results for specific applications, such as the early detection of corrosion in metallic structures, due to the peculiarities of the neutron-to-matter interaction. Thus, x-ray tomography and neutron tomography can be considered as complementary rather than alternative techniques. In this aim, a multipurpose detection system which is able to perform x-ray as well as neutron examinations requiring no or little modifications has been developed. It is based on a multi- channel plate image intensifier, which is coupled to a thin radiation-to-light converter layer as the sensitive element and to a self-constructed CCD camera. The performances of the system are theoretically evaluated in terms of the modulation transfer function of its components, while experimental tests have been carried out by the visualization of sample objects when using either neutron or x-ray sources.
A small prototype cadmium telluride (CdTe) detector optimized for the detection of gamma-rays having an energy of the order of 500 keV was designed. This detector was arranged as an array of 5x5 CdTe crystals, each having dimensions of 2x2x10 cu mm, and was constructed primarily in order to verify its technical feasibility and performances. The initial aim in developing this type of detector was for use in space applications such as measurement of annihilation radiation (511 keV photons) from the galactic center and possibly from extragalactic objects as for example AGN's (Active Galactic Nucleus). Many other applications may also benefit from the use of CdTe position sensitive detectors, in linear or square configuration, such as nuclear medicine diagnostics, nondestructive testing in industrial quality assurance processes, and safety inspection and controls.
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