PubMed Health⌕ Search

Biomedical subjects

A Torresin

Publications and source records attributed to A Torresin.

At least 19 recordsLinked to original sources
PubMed2003

Neuronavigation accuracy dependence on CT and MR imaging parameters: a phantom-based study.

Clinical benefits from neuronavigation are well established. However, the complexity of its technical environment requires a careful evaluation of different types of errors. In this work, a detailed phantom study which investigates the accuracy in a neuronavigation procedure is presented. The dependence on many different imaging parameters, such as field of view, slice thickness and different kind of sequences (sequential and spiral for CT, T1-weighted and T2-weighted for MRI), is quantified. Moreover, data based on CT images are compared to those based on MR images, taking into account MRI distortion. Finally, the contributions to global accuracy coming from image acquisition, registration and navigation itself are discussed. Results demonstrate the importance of imaging accuracy. Procedures based on CT proved to be more accurate than procedures based on MRI. In the former, values from 2 to 2.5 mm are obtained for 95% fractiles of cumulative distribution of Euclidean distances between the intended target and the reached one while, in the latter, the measured values range from 3 to 4 mm. The absence of imaging distortion proved to be crucial for registration accuracy in MR-based procedures.

Algorithms↗
PubMed1998

Treatment planning for radiotherapy in northern Italy: a survey by the National AIFB-AIRO Committee on 3D-Treatment Planning. Italian Association for Biomedical Physics. Italian Association for Radiation Oncology.

BACKGROUND AND PURPOSE: A survey was performed in 1996 to investigate the structures and the process of radiation therapy treatment planning in clinical practice within northern Italy, with particular emphasis on the current and future implementation of 3D equipment and techniques. MATERIALS AND METHODS: Of 57 existing radiation therapy (RT) centres covering a population of 25 million people (45% of the total population of Italy) and treating over 58,000 cancer patients (70% of the cancer cases in Italy) each year, 46 centres were deemed eligible for the survey; a questionnaire was sent to a medical physicist working in each eligible RT centre, 40 of whom responded, making the basis for this report. RESULTS: A dedicated CT scanner was available in 25% of the responding centres and a total of 49 radiation therapy planning systems (RTPS) were reported; none of the RTPS were able to perform 3D calculations, but 50% of the centres had an advanced 2D or 2.5D system. Connection between CT scan and RTPS was by tape or disk in 62% of centres. Immobilization devices were used frequently for head and neck patients (88% of centres), but not for lung (16%) or prostate cancer (24%) patients; the number of contoured slices was largely variable, exceeding 10 in only about 30% of the responding centres. The average working time per patient seemed to closely reflect the number of slices used and the number of critical organs contoured. Finally, the majority of the responding physicists did not favour the use of more than 20 CT slices for 3D treatment planning, nor did they forecast a general spread of this technique in the next 2-3 years. CONCLUSIONS: This survey has shown (1) a heterogeneous picture, with 20% of centres ready to implement 3D techniques and 20% of centres lacking the possibility of planning treatments and (2) a general difficulty in coping with the workload represented by 3D treatment planning.

Data Collection↗
PubMed1997

The long-term efficacy and safety of two different corticosteroids in chronic sarcoidosis.

Deflazacort (DFZ) is claimed to have fewer adverse bone effects than prednisone (PDN) at doses with equivalent anti-inflammatory activity (5 mg PDN = 6 mg DFZ). However, its safety over the long-term has never been tested in a controlled trial. The aim of the present study was to assess prospectively the safety and efficacy of DFZ compared with PDN in previously untreated patients with chronic, histologically proven sarcoidosis needing long-term (> or = 2 yr) corticosteroid therapy. Thirty-six patients were treated with PDN for 32 +/- 18 months and 36 patients were treated with DFZ for 42 +/- 18 months, and followed-up with periodic chest X-ray, 67Gallium lung scan, angiotensin converting enzyme (ACE), serum and urinary calcium levels, spirometry, alveolar diffusion (DLCO) arterial oxygen tension (PaO2), bone mineral content (BMC) (by computed tomography), and a complete biochemical and haematological profile. The two groups were similar as regards sex, age, pulmonary and extrapulmonary involvement, parameters of activity and impairment, and initial BMC. Daily starting doses were 23.2 +/- 11.4 mg DFZ and 22.3 +/- 6.9 mg PDN. One year of trial was completed by 69 patients, 2 yr by 59 patients, 3 yr by 46 patients and 4 yr by 24 patients. Some patients were followed-up for 5-7 yr. The mean daily dose over the whole period was 15 +/- 10 mg DFZ and 10 +/- 6 PDN, starting from 21 +/- 9 and 15 +/- 8 mg in the first year, and progressively declining to a mean of 9 +/- 6 mg in both groups in the fourth year. Chest X-ray, 67Ga score, ACE and forced vital capacity improved significantly in both groups. Urine total calcium improved significantly in the PDN group (345 +/- 27 to 186 +/- 47; P < 0.05) with a similar but non-significant pattern in the DFZ group (270 +/- 28 to 207 +/- 39). Non-significant improvements were observed in DLCO, PaO2 and forced expiratory volume in 1 s in both groups. Drug-related adverse events were more frequent in the PDN group, causing discontinuation of the drug in four PDN patients. Body weight increased mainly in the PDN group [69.9 +/- 0.4 to 73.6 +/- 0.8 kg vs 70.1 +/- 0.4 to 70.0 +/- 0.6 kg in the DFZ group (P < 0.01)]. Bone mineral content dropped under the fracture threshold in most PDN patients, who thus appeared at higher risk for fractures. In fact, six atraumatic skeletal fractures were observed in this group but only one in the DFZ group. Two further patients in the DFZ group and eight in the PDN group were obliged to start corrective measures for bone loss and/or bone pain. At the end of the study, 21 patients (12 DFZ, nine PDN) no longer needed corticosteroids, and the others were taking a maintenance daily dose that controlled the disease adequately. In conclusion, DFZ appeared as effective as PDN in the long-term treatment of chronic sarcoidosis, and it may have fewer side-effects, especially on bone.

Adult↗
PubMed1995

AIDS related neoplasms in Genoa, Italy.

The study defines the epidemiological characteristics of HIV-infection in the population of Genoa and estimates the entity of AIDS-cancer association. The cohort includes 317 subjects resident in the Municipality of Genoa, aged above 14 years and notified prior to 31 December 1991 and/or dead from AIDS in the period 1988-1991. From 1984 to 1991, 44 cases of tumour were recorded. The comparison between the rate ratios found in the AIDS patients' cohort and in the general population of Genoa strengthen the significant association highlighted in literature regarding overall cancer, 26.7 (p < 0.05), and in particular, Kaposi's sarcoma, 3239.4 (p < 0.05); non-Hodgkin's lymphomas, 84.8 (p < 0.05); Hodgkin's lymphomas, 20.6 (p < 0.05). Moreover, a significant increase in the risk of testicular seminoma, 61.5 (p < 0.05) and lung cancer, 18.0 (p < 0.05) is confirmed.

AIDS-Related Opportunistic Infections↗
PubMed1989

[Quantitative analysis of the lung CT in normal subjects and in patients with noncardiac pulmonary edema].

A quantitative analysis was performed of the CT images relative to 7 normal human subjects and to 22 patients affected with ARF (Acute Respiratory Failure). The CT scanner image quality was investigated, and the unit was checked with quality control procedures, in order to assure reliability and reproducibility. In every patient the lung was scanned at 3 different levels--basis, hilum and apex. The frequency distribution of CT numbers was studied. The lung areas were calculated for the different conditions, and the data correlated with functional lung data. A method was then tested to evaluate lung weight; the data obtained did not differ from literature data. All the patients were treated with different positive and expiratory pressure (PEEP). For different PEEP values, the quantitative data from CT analysis were correlated with morphofunctional indices.

Adult↗
PubMed1988

Plasmaexchange plus immunoglobulins for treatment of hypergammaglobulinaemic patients with AIDS and AIDS-related complex (ARC).

AIDS patients often develop a conspicuous although functionally ineffective hypergammaglobulinaemia. We have treated four patients affected by AIDS or AIDS-related complex (ARC) with repeated courses of plasmaexchange coupled with immunoglobulin infusions. The schedule of each course was as follows: one plasmapheresis treatment once a week for 5 consecutive weeks, each treatment amounting to an average exchange of 3000 ml of plasma, replaced by plasma/protein and 5% albumin/physiological saline solutions, and followed by infusion of 15 gr of human immunoglobulins. Each plasmapheresis course was completed by additional weekly administrations of the same amount of human immunoglobulins. In each patient we noted fast cessation of fever, weight gain, and an overall clinical amelioration with decrease of infections, asthenia, and anorexia. Haematological, serological, and immunological parameters (particularly IgG serum levels) also significantly improved after treatment.

AIDS-Related Complex↗
PubMed1987

Antibody-dependent tumour cytolysis by human neutrophils: effect of synthetic serine esterase inhibitors and substrates.

The requirement for serine esterase activity in antibody-dependent cellular cytotoxicity (ADCC) in human neutrophils against Raji target cells has been investigated. The lysis was prevented when the serine esterase inhibitors TPCK and TLCK (chloromethyl-ketone derivatives of tosylamino acids) were introduced into the system. Moreover, neutrophils pretreated with TPCK or TLCK and washed were inhibited as well, via a process unaffected by the presence of adequate amounts of enzymatic substrates. This suggests that the inhibition mediated by TPCK and TLCK is independent of serine esterase blockade, therefore implying the inactivation of some other step crucial to the lysis. The addition of synthetic chymotrypsin substrates (tyrosine and phenylalanine esters) impaired the Raji cell lysis in a dose-related manner without altering the constitution of neutrophil-target conjugates. Trypsin ester substrates were ineffective. These results are in agreement with the involvement of a serine esterase activity with chymotrypsin-like specificity, which should participate in the lysis at a post-binding step. We conclude that neutrophil-mediated ADCC, as developed in our model system, needs the intervention of a serine esterase or esterases, like other systems of cell-mediated cytotoxicity.

Antibody-Dependent Cell Cytotoxicity↗
PubMed1986

Morphological response to positive end expiratory pressure in acute respiratory failure. Computerized tomography study.

Ten patients with acute respiratory failure (ARF), (4 pneumonia, 4 sepsis, 2 polytrauma), underwent computerized tomography (CT) of the lungs, (apex, hilum, base), at 5, 10, 15 cm H2O positive end expiratory pressure (PEEP). The ARF lungs, on CT scan, appeared as a patchwork of normal and dense areas with generally well defined boundaries. Most of the densities were found in the dependent regions. The areas of density were correlated with PaO2 (r = 0.51). The PEEP increase resulted in a significant expansion of total cross-sectional lung surface area. The dense areas decreased significantly at the hilum and base when increasing PEEP while the changes at the apex were not significant. The changes of density with PEEP were highly correlated with the changes in oxygenation (r = 0.91). In the individual patient, however, the modifications of gas exchange can not be entirely predicted from morphological changes, possibly due to a diversion of pulmonary blood flow.

Acute Disease↗
PubMed1986

Adult respiratory distress syndrome profiles by computed tomography.

Ten patients with full-blown ARDS, on mechanical ventilation with PEEP underwent lung CT. Seven normal subjects were also studied. Three tomographic levels (apex, hilum, and base) were selected. The most consistent morphologic finding in ARDS was the presence of densities in the dependent regions of the lung. Assuming that the three levels were a representative sample of the whole lung, the lung weight was computed from the mean CT number and lung gas volume. Analysis of the CT number frequency distribution revealed three definite patterns of distribution: type 1, bimodal, with one mode in the normal CT number range; type 2, unimodal narrow distribution, with the mode in the CT range of water; and type 3, unimodal broad distribution in the abnormal CT number range.

Humans↗
PubMed1984

Measurement of radiation from photochemotherapy equipment using thermoluminescence detector elements (BeO TLD).

The results of experimental dosimetry carried out with beryllium oxide thermoluminiscent material (BeO TLD) are presented. In particular, this material shows a good linearity of response to UV radiation at 365 nm, up to 200 mJ/cm2, and a spectral sensitivity with a peak at 340 nm. The advantages and disadvantages of BeO TLD in comparison with solid state detectors are discussed and suggested for personal and environmental dosimetry of UVA radiation in photochemotherapy.

Beryllium↗
PubMed1983

[Computerized tomography: analysis of the characteristics of various pieces of equipment].

Spatial resolution, statistical noise and patient dose are important parameters for the evaluation of the performances of CT-scanners. These parameters may be combined to develope some "synthetic indices", able to describe intrinsic properties of a CT-scanner (the maximum obtainable spatial resolution and dose efficiency). This type of analysis has been applied to the evaluation of four CT-scanners, three of 3rd and one of 4th generation.

Image Enhancement↗
PubMedDate not supplied

Image quality and dose in computerized tomography: evaluation of four CT scanners.

Spatial resolution, statistical noise, and patient dose are important parameters for the evaluation of the performances of computerized tomography (CT) scanners. These parameters are combined to develop some "synthetic indices," and to be able to describe intrinsic properties of a CT scanner (the maximum obtainable spatial resolution and dose efficiency). This type of analysis has been applied to the evaluation of four CT scanners, three of third, and one of fourth generation.

Radiation Dosage↗