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Intra Operative Radiation Therapy (IORT) is a technique based on delivery of a high dose of ionising radiation to the cancer tissue, after tumour ablation, during surgery, while reducing the exposure of normal surrounding tissue. The Novac7 is a new linear accelerator expressly conceived to perform in the operating room. This accelerator supplies electron beams with high dose rate. Because these peculiar characteristics, classical dosimetric techniques are not able to give at once a real-time response and an extensive measure of the absorbed dose. The new system is composed by a grid of scintillating optical fibres coupled with two arrays of photodiodes. The instrument samples the delivered beam at 100 Hz. The dedicated software collects the two projection-signals and reconstructs the bi-dimensional image. Moreover it provides a series of dosimetric parameters. We studied an appropriate reconstruction algorithm searching the best compromise between the computational complexity and an high precision. An accelerator having energies ranging from 3 to 12 MeV has been used for the tests. The system is able to give a real time response (within 30 seconds), the resolution is of 1 millimeter. The response is linear versus dose and the measures are not affected by the high dose rate. The conclusions confirm the capability of the instrument to overcome problems encountered with classic dosimetry, showing that the results obtained strongly encourage the continuation of this research. Index Terms--Digital system, dosimetry, electron beam, FOS, Intra Operative Radiation Therapy (IORT), photodiode array, real-time acquisition.

Synchrotron-based digital radiography and microtomography devices are powerful, nondestructive, high-resolution research tools. In this paper, we present a linear system with a pixel size of 22.5 [micro]m and a field-of-view (FOV) 13 cm long and about 1 mm high. The system is composed of a linear converter GOS screen coupled to an intensified electron-bombarded CCD (EBCCD) camera, by means of a rectangular-to-linear fiber optic adapter. This optical guide is composed of seven bundles, each one transporting light in a coherent way to preserve spatial information. In this way, a high spatial resolution over an extended FOV is obtained. The detector works as an X-ray scanner by means of a high-precision translation mechanical device with 18 cm travel range. The total FOV obtained this way is 13 cm long and 18 cm high. The aim of this paper is to demonstrate the feasibility of this system to investigate a large area of a bone and to calculate the appropriate histomorphometric parameters. Here we present an investigation gained at ELETTRA synchrotron facility at Trieste, Italy. A monochromatic 34-keV beam has been used for imaging a human proximal femur, about 9 cm in width, with our system. The reconstructed images (13 cm x 13 cm) were cross sections containing femoral head, femoral neck, and greater trochanter. The local variations in trabecular and cortical structure of the examined bone were clearly visible at a level not obtainable with medical CT scanners. The used spatial resolution allowed the visualization of thin trabeculae, which typically lie in a range of 100 [micro]m or lower. The quality of the reconstructed cross-section images confirmed that the system presented is a novel tool for high resolution three-dimensional (3-D) imaging of bone structure, with a pixel size over a volume of interest not achievable with conventional microCT scanners. Index Terms--Biomedical, X-ray detectors, X-ray tomography.

X-ray cone-beam computed tomography (CT) is one of the most powerful non-destructive testing (NDT) technique for the whole 3D inspection of a sample. The development of suitable 2D detectors has permitted the set-up of very fast and efficient CT systems able to collect and reconstruct hundreds of tomographic slices in short time and with a more efficient use of the X-ray flux. At present, this technique is widely applied in industrial field but it can be employed successfully even in the analysis and restoration of archaeological samples. An experimental 3D CT system has been set up at the Physics Department of University of Bologna (Italy) for the investigation of small bronze objects. Preliminary tests have been carried out on an Etruscan fibula and results concerning radiographic inspection, slice tomographic analysis and 3D reconstruction of the object will be presented.

Neutron radiography is currently a well-known technique, which is employed for non-destructive testing in a number of industrial and environmental applications [1, 2]. Originally developed for reactor fuel examinations, it is now effective in detecting small amounts of corrosion and infiltrations of hydrogen or light materials within thick metallic structures due to the particular behaviour of total neutron cross sections [3]. Nevertheless, improvements related to the development of tomographic systems, which allow far better imaging performances, have been achieved only in the last few years, as a consequence, primarily, of the production of large, charge coupled device (CCD) arrays [4]. Nowadays, neutron computed tomography is the technique most suited for the study of the distribution of hydrogen within metallic matrices. In this field, a series of experimental tests were carried out employing a set of nickel samples containing a [H.sub.2]0-[D.sub.2]0 solution in known percentages. It was possible, therefore, to obtain a calibration curve for the total neutron cross section vs. gray level in the reconstructed image.

This work presents a particular application in which cadmium-zinc telluride (CdZnTe) detectors are used in photoconductive mode in a high-energy computerized tomography system for industrial applications. A first-generation tomography facility has been set up at the University of Bologna, based on a 12-MeV pulsed linear accelerator X-ray source and a single 10x10x2 [mm.sup.3] CdZnTe detector. The obtained results show that CdZnTe detectors exhibit better timing performances than CdTe detectors, and are thus more suitable for tomographic applications. Special-purpose signal conditioning electronics have been developed in order to compensate slow and fast signal fluctuations induced by temperature variations and Linac instabilities. In such a way, the dynamic range of the detector has been improved up to more than 3 orders of magnitude. A set of images was acquired in order to evaluate the overall performances of the tomographic facility.

Two types of CdTe detectors operating in different configurations were studied in order to develop small probes having high efficiency and good energy resolution for use in medical and industrial applications. One of the two detectors whose bias electric field was situated perpendicular to the direction of the impinging radiation was shown to have good energy and time resolution. A square matrix was also described which can be used to study the influence of radiation scattered from one detector to those surrounding it.