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P Prati

Publications and source records attributed to P Prati.

9 recordsLinked to original sources
PubMed1994

The updated BESGE spectrometer for pure beta activities in environmental matrices.

This work describes an updated version of a beta spectrometer that measures pure beta emitter activities. The detection system consists of a plastic scintillator surrounded in a 4 pi geometry by large anticoincidence NaI(Tl) scintillators. A thin silicon detector, inserted between the plastic and the sample, helps to reduce the gamma background. A Monte Carlo code, used to calculate the quite complex spectrometer response function to any isotope, is also described.

Beta Particles↗
PubMed1993

Verification of the integral transformation of the projections technique for scatter correction in positron tomographs.

A scatter correction algorithm, based on the integral transformation of the projections, has been implemented when using the C.N.R. positron tomograph in Pisa. The performance of the method has been evaluated by measurements on ad hoc phantoms. The technique allows a significant average reduction of the reconstructed scatter fraction. The limitations of this approach have also been investigated.

Algorithms↗
PubMed1993

A personal dosimeter prototype for static magnetic fields.

A personal dosimeter prototype, for static magnetic fields with three Hall probes, has been designed and built to provide a reliable instrument for long-term analysis. The probe output signals, proportional to the magnetic flux density components of the vector B, are filtered, sampled, and stored in a buffer memory sufficient to cover a whole worker shift. The data sampling rate is high enough to record the operator movements within the fringes of the magnetic field. The content of the buffer memory is then transferred on a personal computer and registered on individual dosimetric cards. The data can be used for personal exposure monitoring.

Electromagnetic Fields↗
PubMed1992

A beta spectrometer for monitoring environmental matrices.

In environmental matrices, pure beta emitters are often present with other beta-gamma emitters. This work describes a beta spectrometer that allows measurement of pure beta-emitter activities of about 10(-2) Bq. The detection system consists of a plastic scintillator surrounded in a 4 pi geometry by large anticoincidence NaI(Tl) scintillators. Solid, liquid, and gaseous samples can be analyzed, and no chemical separation is necessary. The system is particularly useful for 90Sr measurement.

Beta Particles↗
PubMed1992

Prevalence and determinants of carotid atherosclerosis in a general population.

BACKGROUND AND PURPOSE: The aim of this study was to assess the prevalence of asymptomatic carotid atherosclerotic lesions and their relation to principal risk factors. The importance of the relation between asymptomatic carotid atherosclerotic lesions, stroke, and coronary atherosclerosis has been widely discussed, but there are few transversal and longitudinal studies on a general population. METHODS: A noninvasive examination was carried out using high-resolution B-mode ultrasonography, which has been shown to be a reliable tool for epidemiological studies. We examined 630 men and 718 women aged 18-99 years (participation rate, 74.9%). RESULTS: The global prevalence of carotid atherosclerosis was 25.4% in men and 26.4% in women. Intimal-medial thickening was found in 9.4% of men and 11.7% of women. Plaque prevalence was 13.3% in men and 13.4% in women; prevalence of stenotic plaques was 2.7% and 1.5%, respectively. Subjects aged < or = 39 years showed a very low prevalence of any asymptomatic carotid atherosclerotic lesions. In the multiple logistic regression, the analysis of subjects aged > or = 40 years showed a positive significant association between the severity of carotid atherosclerotic lesions (plaques and stenosis) and age (p < 0.001), systolic blood pressure (p < 0.01), cigarette smoking (p < 0.0001), and the protective effect of high density lipoprotein cholesterol (p < 0.037). This analysis did not provide evidence of a clear-cut association between risk factors and intimal-medial thickening. CONCLUSIONS: This population study shows the high prevalence of asymptomatic carotid atherosclerotic lesions in a general population (approximately 25% of adults) and its relation with the classic risk factors. It emphasizes the value of ultrasonography in the detection of early atherosclerotic lesions.

Adolescent↗
PubMed1992

Use of monitoring software to improve the measurement of carotid wall thickness by B-mode imaging.

METHODOLOGY: High-resolution B-mode imaging is a reliable, easily performed and non-invasive means of studying atherosclerosis in superficial blood vessels. Recently it has been used for in vivo studies on the thickness of the common carotid artery wall. It is very sensitive, although the results of practical investigations are highly dependent on both the operator and the direction and angle of ultrasound beams directed towards the vessel. PROTOCOL: We have assessed inter- and intra-observer reproducibility of the measurement of common carotid artery wall thickness in 13 subjects, using two procedures. The first was a standard echographical investigation. In the second procedure, the principal parameters recorded from the first investigation were used to reposition the beam with the same incident angle. RESULTS: Intra-observer variability (correlation coefficient, r = 0.61 for procedure 1 and r = 0.77 for procedure 2) and inter-observer variation (r = 0.58 for procedure 1 and r = 0.71 for procedure 2) were reduced when the second investigation was assisted by reproducibility software. CONCLUSIONS: The proposed method is a reliable and reproducible way of assessing combined intimal and medial wall thickness in the common carotid artery. It may be possible to improve reproducibility using specific software to aid the operator. Since the intimal and medial thickness of the common carotid artery appears to be a sensitive marker of vascular risk, the proposed standardized method of measuring these parameter may allow early detection and assessment of changes.

Aged↗