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. Novac7
and Liac are new linear accelerators expressly conceived to perform in the operating room. These accelerators supply
electron beams with high dose rate. Because of this peculiar characteristic, classical dosimetric techniques are not able to
give at once a real-time response and an extensive measure of the absorbed dose.
In past years the authors realized a prototype for IORT dosimetry able to give the real time bi-dimensional image of dose
distribution on a single layer. In the framework of a research project funded by the INFN (Italian National Institute of
Nuclear Physics), a collaboration between the Physics Department of Bologna, Italy, the Physics Department of Cosenza
and the Medicine Department of Catanzaro, Italy, has studied a new system composed of six layers. Each layer includes
two orthogonal bundles of scintillating optical fibres. The fibres are optically coupled with four arrays of photodiodes as
read-out system. This new system will be able to characterize completely the electron beam in energy, intensity and
spatial distribution. In real time it will be able to measure the 3D dose distribution, providing a full check of quality
assurance for IORT.
The various phases of design, development and characterization of the instrument will be illustrated, as well as some
experimental tests performed with the prototype. We verified that the system is able to give a real time response, which
is linear versus dose and 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 obtained results strongly encourage the continuation of this research.
X-ray cone-beam Computed Tomography is a powerful tool for the non-destructive investigation of the inner structure
of works of art. With regard to Cultural Heritage conservation, different kinds of objects have to be inspected in order to
acquire significant information such as the manufacturing technique or the presence of defects and damages. The
knowledge of these features is very useful for determining adequate maintenance and restoration procedures. The use of
medical CT scanners gives good results only when the investigated objects have size and density similar to those of the
human body, however this requirement is not always fulfilled in Cultural Heritage diagnostics. For this reason a system
for Digital Radiography and Computed Tomography of large objects, especially works of art, has been recently
developed by researchers of the Physics Department of the University of Bologna. The design of the system is very
different from any commercial available CT machine. The system consists of a 200 kVp X-ray source, a detector and a
motorized mechanical structure for moving the detector and the object in order to collect the required number of
radiographic projections. The detector is made up of a 450x450 mm<sup>2</sup> structured CsI(Tl) scintillating screen, optically
coupled to a CCD camera. In this paper we will present the results of the tomographic investigation recently performed
on an ancient globe, created by the famous cosmographer, cartographer and encyclopedist Vincenzo Coronelli.
CCD cameras are widely used for different applications. Recently they are employed for imaging in industrial X-ray
digital radiography or computed tomography inspections. Scientific grade CCD sensors are usually characterized for
what concern defects (bad pixels), resolution capability, spectral sensitivity, dark current, pixel full well capacity and so
on. In former times CCDs were mostly used in astronomy and dark current was one of the most important parameters to
evaluate in this kind of applications because of the long exposure time needed to obtain a good image. Thus, most
manufacturers still refer to noise of a CCD as the background (or dark current) noise. This might be in some cases
misleading. When one wants to compute the effective dynamic range on the full scale of greylevels, in order to match
with the correct number of bit required to quantize the information, and, most of all, to evaluate if the dynamics is
adequate, a different analysis of noise is required. It is possible to find an experimental method to measure noise and to
derive the effective intrinsic dynamic range of a CCD. A case study, carried out on a commercial CCD camera used in a
prototype industrial CT system, is reported in this work and the experimental results are discussed.
Computed Tomography (CT) is one of the principal non-invasive techniques for the investigation of the inner structure of works of art. The main advantage of using CT is that it provides high resolution 3D information of the analyzed object. CT of large objects can be hampered by the long time needed and by the difficulties regarding the experimental arrangements required. In this paper we present a CT study of an ancient large globe (diameter of about 2.2 m). We set-up an <i>ad hoc </i>system for the analysis of the globe <i>in situ</i>. The system consists of an X-ray tube, a detector made of a GOS scintillator and an EBCCD camera, the movement axes, a vertical moving axis for the tube, a horizontal-vertical axis for the detector, and a rotating platform for the globe. The investigation of the entire globe has required the acquisition of about 32000 planar images, for providing the 3D tomographic reconstruction. The analysis of the reconstructed volume has allowed to estimate the composition of the inner structure of the globe.
This work describes the setup of an experimental system for microtomography developed in the framework of a collaboration between the Physics Department of the University of Bologna (Italy) and the Geosphaera Research Center of Moscow (Russia). The main goal of this inspection system is to carry out high-resolution analysis in vitro of biomedical samples as well as nondestructive testing (NDT) of industrial components. The detection system consists of a 30x15 mm<SUP>2</SUP> rectangular fiberoptic taper (ratio 2:1) optically coupled to a cooled 12-bit CCD camera (1024x512 pixels). On the entrance window of the taper is deposited a thin layer of Gd<SUB>2</SUB>O<SUB>2</SUB>S:Tb phosphor which provides the X-light conversion. The image readout is carried out by means of a commercial frame grabber installed on a personal computer and specific software is used for data acquisition and control of the tomographic process. The object under investigation is arranged on a 3-degree micro-positioning system (x-y translation and rotation) and irradiated by an X-ray microfocus beam (up to 200 kVp). The sample can be positioned easily along the source-detector axis in order to obtain a large magnification of details of interest. The X-ray detector has been intensively tested in order to determine its performance in terms of MTF, NPS, and DQE. Moreover, preliminary tests have been carried out on several samples in order to evaluate the performance of the micro-CT system.