Giovanna Loi

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Ultrasound beams propagating in biological tissues undergo distortions due to local inhomogeneities of the acoustic parameters and the nonlinearity of the medium. The spectral analysis of the radio-frequency (RF) backscattered signals may yield important clinical information in the field of tissue characterization, as well as enhancing the detectability of(More)
PURPOSE A problem for clinicians is to mentally integrate information from multiple diagnostic sources, such as computed tomography (CT), magnetic resonance (MR), and single photon emission computed tomography (SPECT), whose images give anatomic and metabolic information. METHODS AND MATERIALS To combine this different imaging procedure information, and(More)
The characteristics of a prototype computer-assisted dynamic multileaf collimator (DMLC), specifically designed for small-field conformal radiotherapy, were evaluated at the Istituto Nazionale Tumori of Milan. The collimating device consists of two opposing banks of 16 pairs of 8 cm thick, 3.6 mm wide tungsten leaves and allows shaping of a radiation field(More)
AIM AND BACKGROUND The aim of this experimental study was to correlate the thickness of acquired CT slices (2, 4 and 8 mm) or MR slices (4 and 7 mm) with the accuracy of three-dimensional volume reconstruction as performed by a commercially available radiation therapy planning system. METHODS We used a cylindrical phantom, with a 15-cm diameter and 20-cm(More)
Stereotactic radiotherapy represents a method to effectively treat brain metastases with high precision and with high doses. Few acute toxicities are associated with stereotactic radiotherapy, however delayed reactions may occur and after six months, 20% of patients can develop radionecrosis. To avoid this adverse effect, in patients with metastases(More)
In stereotactic radiosurgery the choice of appropriate detectors, whether for absolute or relative dosimetry, is very important due to the steep dose gradient and the incomplete lateral electronic equilibrium. For both linac-based and Leksell Gamma Knife radiosurgery units, we tested the use of calibrated radiochromic film to measure absolute doses and(More)
An automated system for the design and manufacturing of individual compensators has been implemented. The system based on computed tomography enables 3D compensation of missing tissue and tissue heterogeneities. The relationship between Hounsfield numbers and electron densities was obtained empirically. Compensator design is based on the calculation of the(More)
In this section, simulated results are presented to quantify the temporal shift induced by the nonlinear phase of the Daubechies filter family over the DWPT coefficient set calculated for different subbands. A 5-MHz central frequency RF echo signal with 40-MHz sampling frequency was considered. The results produced by using four-level decomposition with(More)
A new, simple extrapolation technique to enhance the lateral resolution of pulse-echo imaging systems is presented. The method attempts to build an image that could be obtained with a transducer aperture larger than that physically available, extrapolating the information contained in the image to be enhanced. The extrapolation process requires small(More)
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