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The periodic evaluation of the Faraday cage efficiency for diagnostic Magnetic Resonance is mandatory by Italian legislation and it is recommended by manufacturers. An inadequate shielding could affect clinical images with artifacts, reducing the quality of examinations. The International reference standard for shielding effectiveness measurements is represented by IEEE Standard 299-2006, but it results poorly applicable in Magnetic Resonance sites. In this study, an alternative approach is proposed to simplify the applicability of the IEEE Standard. The experimental set-up for measurements is composed by a signal generator and a transmitting antenna, coupled with the signal generator. The novelty of the proposed methodology consists in the absence of the receiver antenna; for this purpose, the Magnetic Resonance scanner is used. This approach permits to test the entire Faraday cage by means of a single measure. If the Magnetic Resonance device picks up the radiofrequency signal from outside of the cage, this would be visible on the acquired images as a "zipper" artifact. Four Faraday cages, different in building materials, were tested by using the proposed methodology, and the results were compared with those obtained by using the IEEE Standard. The presence of the "zipper" artifact on the images made us inspect the entire Faraday cage and not just the openings, finding that the radiofrequency signal entered from an area without openings, thus denoting a poor construction of the cage. The proposed methodology provides an immediate evaluation of the shielding efficiency, furnishing information on the entire Faraday cage and not only on its apertures. The method is simple, easily reproducible, and constitutes a valid alternative to the IEEE Standard; in particular, during constancy tests.

Atti della Accademia Peloritana dei Pericolanti - Classe di Scienze Giuridiche, Economiche e Politiche, 2020: Trasporto aereo post COVID-19: ritorno al passato o salto nel futuro?

Procedures for Evaluation of Slice Thickness in Medical Imaging Systems

A tattoo is a marking made by inserting ink into the layers of skin to change the pigment for decorations or other reasons. Because it requires breaking the skin barrier, tattooing may carry health risks, including infection and allergic reactions and can modify the thermal and optical properties of the skin tissues. The aim of the present work is the definition of appropriate procedures based on computerized convolution filters to evaluate thermographic images of tattooed skin tissues in voluntary subjects, for dermatological aims. In fact, investigating the infrared radiation emitted by skin tissues is of noticeable importance in order to evaluate the dermatological behavior due to under skin microcirculation. In this context, the telethermographic technique, that put in evidence the thermal radiation emitted from cutaneous surfaces, constitutes the proper instrument to enhance tattoos cutaneous effects. In particular, it appears to be very helpful in the evaluation of skin reactions and scars. At the acquired images we have applied the Image Mean Index algorithm to highlight any differences between thermographic images. After that, we have applied the Sobel Operator and Laplacian convolution filter to compute an approximation of the gradient of the image intensity function. It has been our intention to find out any possible alteration in the cutaneous properties that can occur after the tattooing practices. Moreover, it has been possible to evaluate the presence of any skin damages due to such practices through the comparison between the regions of interest, where the tattoo was applied and the contra lateral not tattooed ones, by enhancing thermally anomalous behaviors and determine all the possible changes in skin tissues and their relative nature, either pathological or not.