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P Viola

Publications and source records attributed to P Viola.

At least 19 recordsLinked to original sources
PubMed2003

The wall correction factor for a spherical ionization chamber used in brachytherapy source calibration.

The effect of wall chamber attenuation and scattering is one of the most important corrections that must be determined when the linear interpolation method between two calibration factors of an ionization chamber is used. For spherical ionization chambers the corresponding correction factors A(w) have to be determined by a non-linear trend of the response as a function of the wall thickness. The Monte Carlo and experimental data here reported show that the A(w) factors obtained for an Exradin A4 chamber, used in the brachytherapy source calibration, in terms of reference air kerma rate, are up to 1.2% greater than the values obtained by the linear extrapolation method for the studied beam qualities. Using the Aw factors derived from Monte Carlo calculations, the accuracy of the calibration factor N(K,Ir) for the Exradin A4, obtained by the interpolation between two calibration factors, improves about 0.6%. The discrepancy between the new calculated factor and that obtained using the complete calibration curve of the ion-chamber and the 192Ir spectrum is only 0.1%.

Algorithms↗
PubMed2003

Experimental dosimetry of a 32P catheter-based endovascular brachytherapy source.

The experimental dosimetry in a water phantom of a 32P linear source, 20 mm in length, used for the brachytherapy of coronary vessels is reported. The source content activity, A, was determined by means of a calibrated well ion-chamber and the value was compared with the contained activity reported in the manufacturer's certification. In this field of brachytherapy dosimetry, radiochromic film supplies a high enough spatial resolution. A highly sensitive radiochromic film, that presents only one active layer, was used in this work for the source dosimetry in a water phantom. The radiochromic film was characterized by electron beams produced by a clinical linac. A Monte Carlo calculation of beta spectra in water at different distances along the source transverse bisector axis allowed to take into account the low dependence of film response from the electron beam energy. The adopted experimental set-up, with the source in its catheter positioned on the film plane inside the water phantom, supplies accurate dosimetric information. The measured dose rate to water per unit of source activity at reference distance, D(r0, theta0)/A, in units of cGy s(-1) GBq(-1), was in agreement with the value reported in the manufacturer's certification within the experimental uncertainty. The radial dose function, g(r), is in good agreement with the literature data. The anisotropy function F(r, theta) is also reported. The analysis of the dose profile obtained at 2 mm from the source longitudinal axis shows that the uniformity is within 10% along 75% of the 20 mm treatment length. The adopted experimental set-up seems to be adequate for the quality control procedure of the dose homogeneity distribution in the water medium.

Algorithms↗
PubMed2002

A passive radon dosemeter suitable for workplaces.

The results obtained in different international intercomparisons on passive radon monitors have been analysed with the aim of identifying a suitable radon monitoring device for workplaces. From this analysis, the passive radon device, first developed for personal dosimetry in mines by the National Radiation Protection Board, UK (NRPB), has shown the most suitable set of characteristics. This radon monitor consists of a diffusion chamber, made of conductive plastic with less than 2 cm height, containing a CR-39 film (Columbia Resin 1939), as track detector. Radon detectors in workplaces may be exposed only during the working hours, thus requiring the storage of the detectors in low-radon zones when not exposed. This paper describes how this problem can be solved. Since track detectors are also efficient neutron dosemeters, care should be taken when radon monitors are used in workplaces, where they may he exposed to neutrons, such as on high altitude mountains, in the surroundings of high energy X ray facilities (where neutrons are produced by (gamma, n) reactions) or around high energy particle accelerators. To this end, the response of these passive radon monitors to high energy neutron fields has been investigated.

Air Pollution, Indoor↗
PubMed2000

[Amnioinfusion: techniques, indications, and controlled retrospective study of 55 cases].

Amnioinfusion is a relatively recent procedure introduced among fetal medicine techniques. Its applications focus on two different methods: transcervical and transabdominal. The first procedure usually is carried out during "intrapartum amnioinfusion" to prevent or treat fetal heart rate (FHR) decelerations related to oligohydramnios or to dilute thick meconium staining of the amniotic fluid. The latter method used during "antepartum amnioinfusion" is usually indicated for severe oligohydramnios in order to avoid the complications related such as pulmonary hypoplasia, deforming effects of oligohydramnios, variable FHR decelerations and intraventricular hemorrhages. Antepartum amnioinfusion, also used to improve ultrasound visualisation in presence of oligohydramnios, is less employed as compared to intrapartum amnioinfusion, therefore its risks are not well established. In order to study possible adverse effects on the mother or foetus, fifty five patients affected by oligohydramnios at 17th-34th week of gestational age were submitted to antepartum amnioinfusion (1-5 procedures) and were matched retrospectively with forty seven women with the same characteristics treated with the conservative and expectant management. The trend of pregnancy was the same for both groups in relation to maternal fever > 38 degrees (10.9% in the amnioinfused group vs 17.0% in control group ns), leukocyte count > 18,000/mm3 (25.5% vs 21.3%, ns), C-reactive protein > 10 ng/ml (10.9% vs 6.4%, ns). The latency period between admission and delivery was significantly longer in the amnioinfused group than in the control one [21 (range 1-98) vs 9 days (range 0-72); p < 0.001] and the frequency of Apgar score < 7 at the 5th min was less represented in the amnioinfused group than in the control group (32.3% vs 66.6%; p < 0.001). In conclusion, it was interesting to note that antepartum amnioinfusion seems to increase the latency period between premature rupture of membranes and delivery, but it remains to clarify if this procedure is as much safe for the fetus as for the mother.

Adult↗
PubMed2000

[Clinical features in subjects with congenital anomalies of the corpus callosum].

The corpus callosum is a connecting structure between the two cerebral hemispheres. Its development occurs between 8th and 20th week of gestation. Anomalies of the corpus callosum are divided into malformative or acquired anomalies and may be isolated or associated with other cerebral malformations. The diagnosis of an alteration of the corpus callosum is fundamentally based on neuroradiological examinations. In our study we evaluate the major clinical findings, the psychomotor development, the electroencephalographic and neuroradiological features in a group of 14 children with congenital callosal anomalies, trying to single out how the associated cerebral malformations interfered with the clinical manifestations and especially the prognosis. It was not possible to highlight a distinctive symptom indicative of the presence of a corpus callosum anomaly; nevertheless in 11/14 children there was a psychomotor delay of varying degree. 42% of our subjects presented epilepsy, with a typical West syndrome in 5/6. Children affected by isolated callosum anomalies did not present any significant clinical manifestations. Finally, we conclude that the determinating factors in the severity of the clinical-electroencephalographic picture as a whole, and especially in the prognosis of our patients are the cerebral malformations associated to the callosum anomalies.

Agenesis of Corpus Callosum↗
PubMed1996

Multi-modal volume registration by maximization of mutual information.

A new information-theoretic approach is presented for finding the registration of volumetric medical images of differing modalities. Registration is achieved by adjustment of the relative position and orientation until the mutual information between the images is maximized. In our derivation of the registration procedure, few assumptions are made about the nature of the imaging process. As a result the algorithms are quite general and can foreseeably be used with a wide variety of imaging devices. This approach works directly with image data; no pre-processing or segmentation is required. This technique is, however, more flexible and robust than other intensity-based techniques like correlation. Additionally, it has an efficient implementation that is based on stochastic approximation. Experiments are presented that demonstrate the approach registering magnetic resonance (MR) images with computed tomography (CT) images, and with positron-emission tomography (PET) images. Surgical applications of the registration method are described.

Brain↗
PubMed1993

Inhibitors of nitric oxide synthase enhance rat ileum contractions induced by ricinoleic acid in vitro.

The effects of NG-nitro-L-arginine methyl ester (L-NAME) and NG-monomethyl-L-arginine (L-NMMA), inhibitors of nitric oxide (NO) synthase, were studied on ricinoleic acid-evoked contractions in rat isolated ileum. Ricinoleic acid (10(-5) to 10(-4) M) caused a concentration-dependent contraction. Addition of L-NAME (30-300 microM) or L-NMMA (30-300 microM) to the Tyrode's solution increased in a concentration-dependent fashion the amplitude of the ricinoleic acid-evoked responses. L-Arginine (900 microM), a natural substrate of NO synthase, but not D-arginine (900 microM), counteracted the effect of L-NAME (300 microM). The potentiating effect of L-NAME was also prevented by sodium nitroprusside (0.1-1 microM), a generator of NO. These results provide evidence that endogenous NO may modulate the contraction of rat ileum induced by ricinoleic acid. As the contraction induced by ricinoleic acid is not blocked by tetrodotoxin (0.6 and 6.0 microM) the contractile effect of ricinoleic acid results mainly from a direct action on the smooth muscle.

Amino Acid Oxidoreductases↗
PubMed1993

Inhibition of intestinal motility and secretion by flavonoids in mice and rats: structure-activity relationships.

Intraperitoneal administration of some flavonoids (apigenin, flavone, kaempferol, morin, myricetin, naringin and rutin; 12.5-50 mg kg-1) significantly (P < 0.05-0.01) reduced small (28-69%) and large (83-134%) intestinal transit in mice. Other flavonoids (naringenin, silibinin, silymarin and taxifolin, 100-200 mg kg-1) reduced (23-41%; P < 0.05-0.01) intestinal transit at doses of 100-200 mg kg-1 while hesperitin, catechin and phloridzin (up to 200 mg kg-1) had no effect. This effect was antagonized by yohimbine (87-96%) and phentolamine (87-91%) but not by prazosin, propranolol, atropine, hexamethonium, mepyramine, cyproheptadine and naloxone. Yohimbine (92-96%) also antagonized the inhibitory effect of flavonols (12.5-50 mg kg-1) (P < 0.05-0.01) on intraluminal accumulation of fluid and diarrhoea induced by castor oil. By contrast, verapamil potentiated the flavonol effect. It is suggested that these effects, influenced by the structure of the molecules, are mediated by alpha 2-adrenergic receptors and calcium.

Animals↗
PubMed1985

Patients' assessment of quality of care: a survey of a group of breast cancer patients in Italy.

Patients' assessment of quality of care was investigated in 825 women with breast cancer treated in a group of specialized and non-specialized institutions in Italy. A 10-page mail questionnaire explored patients' adjustment to the disease, satisfaction with care, and quality of the information on diagnosis and treatment. Most of the 428 (52%) responders reported good or acceptable adjustment to the disease (as reflected by acceptable performance in some daily living activities), and favorable judgment about care providers, but many women complained of hospital organizational deficiencies. A contradictory picture emerged regarding the quality of information. Completeness and thoroughness appeared seriously deficient when examined objectively using a series of explicit predefined criteria, but patients' assessments showed in most cases moderate or high satisfaction. The paper presents these results and discusses pros and cons in the use of patients' opinions for evaluation of quality of care.

Adaptation, Psychological↗
PubMed1985

Follow-up after mastectomy for breast cancer. Observations in 96 patients.

From 1978 to 1982 at the Oncology Unit of the Rho Hospital, we followed 96 women who had been operated for breast cancer. In 22 cases (23%) the first signs of recurrence were changes in the following: physical examination (9), symptoms (7), ESR (3), bone scan (2), alkaline phosphatase (1), chest X-ray (1). An adequate follow-up schedule is based on the following: a) limited examinations causing little disturbance to the patient, easily feasible, sensitive, specific, and of limited cost; b) lead-intervals of various tests set according to the risk of relapse; c) critical periodic review of the series, with constant updating of information in the literature.

Breast Neoplasms↗
PubMed1983

Anionic glycoproteins and their hexosamine content in neoplastic patients: relationships with the clinical stage and the course of the disease.

In 40 healthy subjects, in 47 non-cancer patients, and in 142 cancer patients, perchloric acid soluble glycoproteins (PASG) and hexosamines were determined to investigate their tumor specificity and correlation with the tumor mass. Cancer patients were divided into three subgroups: CI, no evidence of cancer (after radical surgery); CII, locoregional disease; CIII, widespread metastatic disease. There was no statistically significant difference in PASG among normals, non-cancer and CI patients; hexosamines in non-cancer and in CI patients were higher (P less than 0.002) than in normals; both PASG and hexosamines were significantly higher in CII and CIII patients than in normals (P less than 0.001). In the CI group, 62% of patients who relapsed within 10 months after surgery had high hexosamine values, whereas 69% of patients who did not relapse showed normal levels (P less than 0.05). PASG and hexosamines significantly increased with cancer progression and decreased when objective response to treatment was achieved. They are not tumor specific, but seem to be related to the tumor burden; hexosamines seem to have some prognostic value.

Adult↗
PubMed1981

Heart blocks during sleep: a case report in a healthy subject.

Cardiac arrhythmia was fortuitously discovered during an experimental sleep recording in a healthy 50-year-old man. a 24 hr electrocardiographic (ECG) monitoring revealed the prevalence of these abnormalities during sleep and their absence during the awake period. Sleep and ECG were recorded during 4 consecutive nights. Numerous (500-1, 100 events/night) heart blocks and sinus pauses occurred 60-80 min after going to bed. They were never observed during awakenings and were exacerbated during paradoxical sleep. The atrioventricular blocks were of the Wenckebach-Luciani type. No other abnormality was found. These conduction abnormalities are discussed as possibly due to phasic increases in vagal firing, which during paradoxical sleep would be superimposed on the tonic increase in heart rate.

Electrocardiography↗