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To benchmark regional standard practice for paediatric cranial CT-procedures in terms of radiation dose and acquisition parameters. Paediatric cranial CT-data were retrospectively collected during a 1-year period, in 3 different hospitals of the same country. A dose tracking system was used to automatically gather information. Dose (CTDI and DLP), scan length, amount of retakes and demographic data were stratified by age and clinical indication; appropriate use of child-specific protocols was assessed. In total, 296 paediatric cranial CT-procedures were collected. Although the median dose of each hospital was below national and international diagnostic reference level (DRL) for all age categories, statistically significant (p-value

Our objective was to show that in low-dose MDCT of the sinuses in children the effective dose can be lowered to a level comparable to that used for standard radiographic images, with resultant CT scans that are still of diagnostic image quality.In standard radiographic examinations of sinuses (anteroposterior and lateral views) with 75 kV, 20 mAs, and 3-mm aluminum filtration in 69 children (mean age, 4.2 years), the dose-area-product (DAP; mGy x cm2) was measured and converted to effective dose (mSv) according to coefficients published by the British National Radiological Protection Board. Another group of 125 children (mean age, 6.8 years) underwent low-dose MDCT of the sinuses with 6- or 16-MDCT in two phases and with different scanning protocols. An effective dose for MDCT was calculated from conversion of the dose-length-product (DLP, mGy xm) according to age.The mean effective dose (E) for standard radiography was 0.0528 mSv. The mean E value for low-dose MDCT was 0.096 mSv in the first phase of the study but could be lowered in the second phase to 0.0531 mSv by a combination of higher pitch and faster scan rotation time in our scan protocols, which results in diagnostic image quality at a very low dose. Statistical analysis showed no significant differences in effective dose between radiography and MDCT of the second phase.With modern MDCT technology, low-dose CT of the sinuses in children can yield diagnostic image quality using an effective dose comparable to that used for standard radiography.

Magnetic resonance imaging (MRI) is now considered the diagnostic study of choice for evaluation of patients with suspected acoustic schwannoma. This retrospective study of 118 MR examinations presents an analysis of the MR findings of 89 acoustic tumours in 86 patients. The method of examination included precontrast and gadolinium(Gd)-enhanced MRI in 72 and plain MRI in 14 patients. The common MR-appearances of acoustic schwannomas were: on T1-weighted images (WI) isointense (36%) or slightly hypointense (64%) relative to the brainstem; intense and homogeneous contrast enhancement in 62%; the shape of the tumour was round or oval in 71%; the tumour was centred at/or located in the internal auditory canal (IAC) in 80%. The small acoustic schwannomas were mostly round or oval in shape and showed homogeneous signal intensity (SI) both before and after Gd. The larger acoustic tumours were more heterogeneous in morphology and SI. The significance of these and other signs, early diagnosis and differential diagnosis are discussed.

Ces dernières vingt années ont été fertiles en réflexions sur les modes de production et leur gestion. Nous proposons une approche synthétique dont il ressort que les modes de production du futur ne seront pius nj MRP ni môme flux tirés mais bien flux poussés ou production synchrone, encore que ce dernier mode sera sensiblement différent du mode JAT actuel dont il est révolution

A case of multiple inverted papillomas of both ureters, in association with a bladder carcinoma, is presented. Inverted papilloma is a rare benign urothelial tumor. Because of its curability by conservative surgery, it should be considered in the differential diagnosis of a ureteral filling defect and ureteral obstruction. Inverted papilloma may be associated with carcinomas of the urinary tract.

Magnetic resonance imaging (MRI) is now considered the diagnostic study of choice for evaluation of patients with suspected acoustic schwannoma. This retrospective study of 118 MR examinations presents an analysis of the MR findings of 89 acoustic tumours in 86 patients. The method of examination included precontrast and gadolinium(Gd)-enhanced MRI in 72 and plain MRI in 14 patients. The common MR-appearances of acoustic schwannomas were: on T1-weighted images (WI) isointense (36%) or slightly hypointense (64%) relative to the brainstem; intense and homogeneous contrast enhancement in 62%; the shape of the tumour was round or oval in 71%; the tumour was centred at/or located in the internal auditory canal (IAC) in 80%. The small acoustic schwannomas were mostly round or oval in shape and showed homogeneous signal intensity (SI) both before and after Gd. The larger acoustic tumours were more heterogeneous in morphology and SI. The significance of these and other signs, early diagnosis and differential diagnosis are discussed.

MR imaging is the study of choice for the examination of patients with suspected acoustic schwannoma, because of its high sensitivity, especially after the use of contrast material. This essay illustrates the common MR features of acoustic schwannomas as seen in a study of 84 tumors. We pay special attention to the role of MR imaging in the distinction between acoustic schwannoma and meningioma.

Charged-current neutrino and antineutrino interaction cross sections have been measured in the energy range 10 to 50 GeV using BEBC filled with a neon-hydrogen mixture. At these energies, σ/E was measured to be (0.73±0.08) 10−38 cm2/GeV per nucleon for neutrinos and (0.32±0.06) 10−38 cm2/GeV per nucleon for antineutrinos.

We present the charged multiplicity distribution in p p interactions at √s=540 GeV. Moments of the distribution are given, and compared with KNO scaling predictions. An estimate of the particle composition at collider energies is also made.

The Frank elastic constant for twist deformation k 22, has been determined as a function of temperature for 5CB and compared with values cited in literature. The results, together with the values of the elastic constants for splay, k 11, and bend, k 33, which have been measured recently by Bradshaw et al. and the values for k 11/k 22, and k 33/k22 as found by Hara et al. suggest that the values of Karat and Madhusudana (corrected by Bunning et al.) are somewhat too low.

Results are presented from the first p p colliding beam runs at the CERN ISR, using the UA5 streamer chamber detector. p p interactions at s = 53 GeV are compared with pp data taken in the same experiment. The results are in good agreement with extrapolations of low-energy p p data.

In addition to one previously reported event, a second event, in which a positron is observed together with a strange particle and a negative muon, has been seen in the bubble chamber Gargamelle exposed to the CERN neutrino beam. The level of the background for this type of event is found to be very low. The data strongly indicate the existence of a new type of interaction leading to a charged lepton pair correlated with a strange particle in the final state. The interpretation of these two events in terms of production of a charmed hadron is presented.

The UA5 Monte Carlo program, consisting of a non-diffractive event generator GENCL, a diffractive event generator DIFFR and a tracking program are described. The inputs to the event generators are explained in detail. Their outputs are compared to available data from the S p pS Collider, and the agreement is shown to be good. The importance of some features of the generators are discussed. It is shown that cluster production and leading baryons are necessary to describe non-diffractive phenomena.

For e + energy > 0.3 GeV and 10 GeV ƒ = (v μ + Ne → μ − e + )/(v μ + Ne → μ − ) = (0.41 ± 0.15)% ; (ii) 1.2 ± 0.5 neutral strange particles are produced per μ − e + event; (iii) the lifetime of possible positron-parent particles is −10 s (90% C.L.); (iv) the cross section for direct e + production via the neutral current is + , decaying into e + … is −3 times that for μ − production, implying M (L + ) > 10 GeV.

About 200 and 60 candidates for electron neutrino and antineutrino interactions, respectively, have been analyzed in the heavy liquid bubble chamber Gargamelle exposed to the CERN PS neutrino beam. Evidence for scaling has been found for these interactions, with slopes of the cross sections in good agreement with those obtained for muon neutrino and antineutrino events in the same chamber. No evidence appears for oscillations of neutrinos or antineutrinos, which would induce in the present experiment an excess of electron or positron events. The corresponding limits are given as functions of the mixing parameter, for the finite mass Majorana neutrinos. The possibility of a multiplicative law for the lepton number has also been investigated. A search for isolated electron-positron pairs revealed no excess in the forward direction, in contradiction to the expectation for muonic neutrino and antineutrino decays. The corresponding limits on the c.m. half lifetimes are given.

We have fully analysed all events with a single electron obtained in an exposure of BEBC to the 350 GeV wide-band neutrino beam at CERN. The data agrees well with expectations based on the calculated ν e flux and assuming μ−e universality. Using both the rate and the kinematic distributions, improved limits are set on ν e → ν X , ν μ → ν e , ν μ → ν τ mixing.

In the Gargamelle neutrino experiment, three unambiguous candidates for the reaction ν μ + e − → ν μ e − have been observed corresponding to a cross section for a recoil electron energy within the range 0.3 e − GeV of 0.06 × 10 −41 E ν ( GeV ) cm 2 / electron . The calculated background is 0.44 ± 0.13 events and the probability that all three candidates could be due to this background is 1%.

First results from the UA5 detector on charged particle production at √s = 540 GeV in the pseudorapidity range ∣ν∣

An upper limit of 3 × 10−42 Eν cm2 per electron, at 90% confidence level, has been obtained for the cross section of the process νμ + e− → νμ + e−, interpreted in the usual V-A framework, for an electron recoil energy larger than 0.3 GeV. This estimate is based on the observation of one candidate event in exposures of Gargamelle to the CERN PS neutrino beam.

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First results from UA5 on charged particle multiplicities from pp interactions at √s = 540 GeV are presented. A value of 27.4 ± 2.0 is obtained for the mean charged multiplicity 〈nch〉 of produced hadrons. This excludes an s 1 4 behaviour of 〈nch〉 in going from ISR to Collider energies, but is not in disagreement with an extrapolation using a quadratic fit in ln s to previous lower energy data up to ISR energies. © 1981., 0, SCOPUS: ar.j, info:eu-repo/semantics/published

The pseudorapidity distribution of photons produced in pp̄ interactions at s=540GeV has been measured and compared with that of charged particles. The correlation between photon and charged-particle production has been studied. A search amongst high multiplicity events for any having the properties of the Centauro events reported in cosmic-ray experiments has revealed no candidates in a sample of 3600 inelastic events. © 1982., 0, SCOPUS: ar.j, info:eu-repo/semantics/published

First results are presented on kaon and lambda yields in pp̄ collisions at s=540 GeV. Our data show an increase in the K π ratio and especially in kaon mean transverse momentum relative to results at lower energies. © 1982., 0, SCOPUS: ar.j, info:eu-repo/semantics/published

New results are presented of an analysis of pictures taken during an exposure of Gargamelle to the CERN ν beam in 1975. In addition to three ν μ +N→ μ − +e + +V 0 + hadrons events previously reported, an excess is found of events of the type ν μ +N→ μ − +e + + hadrons without V 0 . An analysis of strange particle production in charged current events suggests a possible violation of the ΔS = ΔQ rule. Interpreted in terms of charm production, the data permit an estimate of branching ratios and production rate of charmed particles. A limit is also placed on charmed particle production by neutral currents.

Results are presented on exclusive single-pion production in the bubble chamber Gargamelle, filled with a light propane-freon mixture, and exposed to the focused neutrino wide-band beam at the CERN PS. The results are corrected for nuclear reinteractions. The isospin structure of the weak neutral current is analysed using all four single-pion channels. The isovector-isoscalar interference term is measured and found to differ from zero by two standard deviations. Evidence of Δ production by the weak neutral