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Biomedical subjects

A Fazzi

Publications and source records attributed to A Fazzi.

At least 19 recordsLinked to original sources
PubMed2006

A solid state microdosimeter based on a monolithic silicon telescope.

A monolithic silicon telescope, consisting of a DeltaE and an E stage-detector ( approximately 1.9 microm and 500 microm thick, respectively), was coupled to a polyethylene converter in order to investigate the feasibility of a solid state microdosimeter with respect to the field-funnelling effect. This work discusses the preliminary results of an analytical approach for the correction of a spectrum measured with this silicon-based microdosimeter for tissue-equivalence and geometrical effects. The device was irradiated with 2.7 MeV monoenergetic neutrons at the INFN-Laboratori Nazionali di Legnaro (Legnaro, Italy). The non tissue-equivalence of silicon was corrected by exploiting the signals generated in the E-stage. The correction for the sensitive volume geometry was optimised by taking into account the track length distribution of the recoil-protons generated in the converter. The derived dose distribution of the energy imparted per event was compared to the one measured with a cylindrical tissue-equivalent proportional counter (TEPC). The agreement is satisfactory.

Computer-Aided Design↗
PubMed2005

A feasibility study of a solid-state microdosimeter.

A solid-state silicon detector is a challenging device for microdosimetry, mainly because it can provide sensitive zones of the order of a micrometer. Moreover, these detectors are characterized by a high spatial and a good energy resolution. However, they may present some limitations, such as: (i) the minimum detectable energy which is limited by the electronic noise; (ii) radiation hardness; (iii) the geometry of the sensitive volume; (iv) the field-funnelling effect; (v) the non-tissue-equivalence of silicon. This work discusses a feasibility study of a microdosimeter based on a monolithic silicon telescope, consisting of a DeltaE and an E stage-detector, about 1 and 500 microm thick, respectively. Charges are collected separately in the two stage-detectors. The use of the DeltaE stage coupled with a tissue-equivalent converter was investigated as a solid-state microdosimeter. Irradiations with monoenergetic neutrons were performed at the INFN-Laboratori Nazionali di Legnaro (Italy). The field-funnelling effect appears to be negligible from the comparison of the experimental data with the results of Monte Carlo simulations, performed with the FLUKA code. The preliminary results of an analytical approach for the correction for geometrical effects and tissue-equivalence are also presented.

Journal Article↗
PubMed2005

Feasibility study of a personal dosemeter based upon silicon diodes used in remote controlling.

The availability of low cost personal dosemeters is very important for routine worker monitoring. The aim of this work is to evaluate the performance of commercial silicon diodes, commonly used for infrared communication, as a personal radiation monitor. The instrument prototype was characterised both as an area monitor and a personal monitor. Instrument response was measured in the energy range form 37 keV to (60)Co energy. The angular response was also evaluated too.

Dose-Response Relationship, Radiation↗
PubMed2005

Performance of a neutron spectrometer based on a PIN diode.

The neutron spectrometer discussed in this work consists of a PIN diode coupled with a polyethylene converter. Neutrons are detected through the energy deposited by recoil-protons in silicon. The maximum detectable energy is -6 MeV and is imposed by the thickness of the fully depleted layer (300 microm for the present device). The minimum detectable energy which can be assessed with pulse-shape discrimination (PSD) is -0.9 MeV. PSD is performed with a crossover method and setting the diode in the 'reverse-injection' configuration (i.e. with the N+ layer adjacent to the converter). This configuration provides longer collection times for the electron-hole pairs generated by the recoil-protons. The limited interval of detectable energies restricts the application of this spectrometer to low-energy neutron fields, such as the ones which can be produced at facilities hosting low-energy ion accelerators. The capacity to reproduce continuous neutron spectra was investigated by optimising the electronic chain for pulse-shape discrimination. In particular, the spectrometer was irradiated with neutrons that were generated by striking a thick beryllium target with protons of several energies and the measured spectra were compared with data taken from the literature.

Equipment Design↗
PubMed2004

A recoil-proton spectrometer based on a p-i-n diode implementing pulse-shape discrimination.

A recoil-proton spectrometer was created by coupling a p-i-n diode with a polyethylene converter. The maximum detectable energy, imposed by the thickness of the totally depleted layer, is approximately 6 MeV. The minimum detectable energy is limited by the contribution of secondary electrons generated by photons in the detector assembly. This limit is approximately 1.5 MeV at full-depletion voltage and was decreased using pulse-shape discrimination. The diode was set up in the 'reverse-injection' configuration (i.e. with the N+ layer adjacent to the converter). This configuration provides longer collection times for the electron-hole pairs generated by the recoil-protons. The pulse-shape discrimination was based on the zero-crossing time of bipolar signals from a (CR)2-(RC)2 filter. The detector was characterised using monoenergetic neutrons generated in the Van De Graaff CN accelerator at the INFN-Laboratori Nazionali di Legnaro. The energy limit for discrimination proved to be approximately 900 keV.

Body Burden↗
PubMedDate not supplied

Pathologic synovial plica of the knee. Results of conservative treatment.

Observations of 136 cases of pathologic synovial plica of the knee were analyzed with regard to etiology, symptoms, and the results of conservative treatment. The results obtained with conservative treatment were good in 40% of cases, average in 20%, and poor in 40%. In our opinion, these results justify the treatment of this condition with physical therapy before proceeding with surgical correction. The objective of physical therapy was to decrease the compressive forces in the anterior compartment of the knee by increasing the structural flexibility of the flexor and extensor muscles. This increase in flexibility was obtained by instituting stretching exercises for the hamstrings, gastrocnemius, and quadriceps.

Adolescent↗
PubMedDate not supplied

[Psychological care to polytraumatized patients].

This article calls attention to the importance of the psychological assistance during the period of hospitalization and rehabilitation of polytraumatic patients. The authors comment on their experience with these patients giving special attention to the disorders resulting from corporal damages that will affect their professional and familiar lives. They emphasize the importance of a multiprofessional approach during the period of the rehabilitation process.

Critical Care↗
PubMedDate not supplied

[Magnetic resonance of spinal osteoid osteoma].

The authors report one case of spinal osteoid osteoma localized in the thoracic spine that was imaged through M. R. I. They report the M. R. I. aspects of the tumor. Precise localization is necessary for the correct surgical approach.

Adolescent↗
PubMedDate not supplied

[Back pain and lumbo-sciatic pain: psychosomatic approach].

The authors call attention to the importance of an integrated multi-professional attendance of patients with low back pain. It is pointed out that social economic and psychologic factors contribute to manifestations of many lumbar spine disorders and that the knowledge of psychosomatic concepts will help to a better understanding of the symptoms presented by these patients.

Adult↗
PubMedDate not supplied

[Traumatic disk hernia of the cervical spine].

The authors present 26 cases of traumatic disc herniation in the cervical spine submitted to anterior discectomy. All of the patient presented neurologic deficit, being 18 classified as Frankel A, three as Frankel B, 2 Frankel C and 3 Frankel D. There were observed three deaths in the immediate post-operative period due to respiratory insufficiency in patients classified as Frankel A. The other 23 cases have a follow-up of 14 months (6-84 months), presenting improvement of the neurologic deficit in six patients classified as Frankel B, C and D and only one as Frankel A. The authors emphasize the importance of the image methods in the diagnosis of this lesion.

Cervical Vertebrae↗
PubMedDate not supplied

[Surgical treatment of idiopathic scoliosis in adolescents by the Harrington method].

Forty six patients with idiopathic scoliosis were treated according the Harrington method. The surgical treatment was done with the Harrington distraction rod, and vertebral arthrodesis with autogenous iliac bone graft. The patients wore a Risser-Cotrel body-cast for nine months but started walking two days after casting. Good clinical results were obtained in all the patients. Final curve correction was 40%. In this series of patients no pseudoarthrosis occurred.

Adolescent↗
PubMedDate not supplied

[Clinico-radiological evaluation of patients with ankylosing spondylitis].

The authors prospectively investigated 20 ankylosing spondylitis patients with 11 years of mean disease duration. The researched variables were related to patients activity and severity of symptoms, as well to the main axial skeleton radiological changes. The results showed that all the patients presented different degrees of radiological sacroiliitis, while 90% revealed apophyseal joints ankylosis, therefore demonstrating the importance of these radiological signs for the diagnosis of the ankylosing spondylitis.

Adult↗