[en] Features extraction from medical images represents a fundamental step for shape recognition and diagnostic support. The present work faces the problem of the detection of large features, such as massive lesions and organ contours, from mammographic images. The regions of interest are often characterized by an average grayness intensity that is different from the surrounding. In most cases, however, the desired features cannot be extracted by simple gray level thresholding, because of image noise and non-uniform density of the surrounding tissue. In this work, edge detection is achieved through the fast marching method (Level Set Methods and Fast Marching Methods, Cambridge University Press, Cambridge, 1999), which is based on the theory of interface evolution. Starting from a seed point in the shape of interest, a front is generated which evolves according to an appropriate speed function. Such function is expressed in terms of geometric properties of the evolving interface and of image properties, and should become zero when the front reaches the desired boundary. Some examples of application of such method to mammographic images from the CALMA database (Nucl. Instr. and Meth. A 460 (2001) 107) are presented here and discussed

[en] The Compton profile is a correction of the Klein-Nishina cross-section for the motion of the electrons. This correction modifies the shape of the Compton peak in the spectrum of the scattered photons and it depends on the atomic wave functions of the electrons inside the sample. Thus, the Compton profile can be used as a probe for the electronic structure of atoms or molecules. However, the shape of the Compton peak is also influenced from the geometrical factors or apertures of collimators used in the experimental setup. Since the energy of the Compton scattered photons depends on the scattering angle, in principle, the best choice is to collimate the detector as much as possible, but, as a drawback, this means also a drastic reduction of the photon flux at the detector. This paper deals with a study of the influence of the geometrical factor on the discrimination of different biological elements. The results can be extended to other materials. Some results from reference biological samples are reported and discussed

[en] Images of soft materials are obtained using image intensifier based X-ray system (Rao et al., Nucl. Instr. and Meth. A 437 (1999) 141). The interior of the soft material is visualized using the novel software in order to know the distribution of attenuation coefficient in terms of density. The novel software is based mainly on graphical library and applicable to several operating systems without any change. It can be applied to several applications starting from biomedical to industries, for example, quality control. The results for walnut and brew tooth are presented as a set of images from the internal parts of the sample. A description of the principal parameters required for tomographic visualization is given and some results based on this technique are reported and discussed

[en] Conventional algorithms for tomographic reconstruction require the acquisition of a complete set of projections at uniform angular displacements. In many cases, however, the geometry of the sample or a loss of data can significantly reduce the range of the available projections. Several algorithms have been proposed in literature to handle such situations, but their performances are low or they require strong constraints and hypothesis about the nature of the sample or the data. Here a new method is proposed. It is based on a novel morphing technique, which affords in general terms the problem of curve matching and is here specialized to the case of tomographic reconstruction. The proposed algorithm is very fast in comparison to other approaches having similar effectiveness; furthermore, it allows one to obtain good quality images even when a significant fraction of the views is absent, without any hypothesis about the nature of the sample or the kind of measurement. The results obtained by applying this technique to the Shepp-Logan phantom and to a clinical scan are reported here and discussed

[en] A multiple CT-scanner is described, which contemporaneously uses transmitted, scattered and fluorescent X-rays. This scanner is characterized by small size X-ray tube and detectors. Examples of applications are shown

[en] Quantitative phase retrieval is experimentally demonstrated using the Inverse Compton Scattering X-ray source available at the Accelerator Test Facility (ATF) in the Brookhaven National Laboratory. Phase-contrast images are collected using in-line geometry, with a single X-ray pulse of approximate duration of one picosecond. The projected thickness of homogeneous samples of various polymers is recovered quantitatively from the time-averaged intensity of transmitted X-rays. The data are in good agreement with the expectations showing that ATF Inverse Compton Scattering source is suitable for performing phase-sensitive quantitative X-ray imaging on the picosecond scale. The method shows promise for quantitative imaging of fast dynamic phenomena.

[en] Traditionally X-ray sources used in mammography are X-ray tubes. Synchrotron radiation sources have shown better imaging performances, but they cannot replace conventional X-ray tube systems in routine mammographic examinations. A new generation of quasi-monochromatic, high-flux X-ray sources is currently under development, based on Thomson backscattering of photons produced by a laser on a highly focused electron beam. They offer important potential applications in the medical field. In this work, we will discuss an application in the field of mammography, by using a Monte Carlo code, in which the effect of different spectral distributions and different mean energies on the image quality is studied. A test object, consisting of a block of Polymethyl Methacrylate (PMMA) containing air-filled holes (Contrast Detail Phantom) is used for the simulations. Results show 1-2 keV of energy spread for a quasi-monochromatic source produce images whose quality is comparable within 3-4% with those obtained by monochromatic sources and whose visibility is dramatically enhanced with respect to images obtained with X-ray tubes

[en] Mammography is a challenging field of medical imaging. Early detection of breast cancer requires identifying small contrast details. The choice of the appropriate monochromatic energy enhances the visibility of such details. Thomson scattering source can provide tunable quasi-monochromatic X-ray beams. In this work, we investigate by Monte Carlo simulations the optimal monochromatic energy to image mammographic phantoms. In order to mimic a Thomson scattering source, we consider the effect on image quality of the presence of an energy spread and of the presence of higher-order harmonics.

[en] The Computer Assisted Library for MAmmography (CALMA) project is a 5 years plan developed in a physics research frame in collaboration between Istituto Nazionale di Fisica Nucleare and many Italian hospitals. At present a large database of digitized mammographic images (more than 6000) was collected and a software based on neural network algorithms for the search of suspicious breast lesions was developed. Two tools are available: a microcalcification clusters hunter, based on supervised and unsupervised feedforward neural network, and a massive lesion searcher, based on a hibrid approach. Both the algorithms analyzed preprocessed digitized images by high-frequency filters. Clinical tests were performed to evaluate sensitivity and specificity of the system, considering the system as alone and as second reader. Results show that the system is ready to be implemented by medical industry. The CALMA project, just ended, has its natural development in the Grid Platform for CALMA project, where distributed users join common resources (images, tools, and statistical analysis)

[en] The proper use of imaging equipment in radiological units is based on an appropriate knowledge of the physical characteristics of the X-ray beam used. The FLUXEN PROJECT is working on a portable apparatus which, together with dedicated software, is able to perform an exact spectral reconstruction of the radiation produced in diagnostic X-ray tubes. The apparatus characterizes the energy spectrum of radiological tubes and also provides a measurement of the emitted flux. The acquisition system is based on a commercial CZT detector (3x3x2 mm³), produced by AMPTEK, cooled by a Peltier cell, with a high efficiency in the diagnostic X-ray energy range and modified in the shaping electronics so as to obtain a faster response. The acquiring section lies on a NuDAQ I/O card with a sampling frequency of up to 20 MHz. The signal produced by the X-ray tube is wholly acquired and an off-line analysis is made so as to make possible an accurate recognition of pile-up events and a reconstruction of the emitted spectra. The reconstructed spectra of a General Electric Senographe DMR mammographic X-ray tube are shown