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Recently, high resolution micro-radiography became of great interest. Very thin scintillator layers of about 5–20 micrometres are used to achieve spatial resolution below one micrometre in application for low energy X-ray micro-radiography [1]. Such thin screens are mainly used in micro-XCT and nano-XCT systems (X-ray Computed Tomography) with either micro-focus X-ray tubes or with synchrotron sources [2]. This work deals with a high-resolution CCD camera together with different optical systems and different single crystal scintillators in application for low energy X-ray micro-radiography. The light distribution on the screen is re-imaged by an optical system (usually represented by classical microscope objective together with a field lens) to a high-resolution CCD or CMOS chip. A theoretical modelling and practical comparison of a camera set-up has been done to investigate the system resolution limits. Thin screens were prepared from YAG:Ce scintillator. The resolution is presented on test patterns. As recent optical systems are limited to the classical microscopy objectives only, we further investigate a possibility to develop a custom-made objective fully dedicated to X-ray imaging application.

The characteristic of the thin plate (O38x0.25mm) of scintillation detectors YAP:Ce (YAlO3 doped Ce) and YAG (Y3Al5O12 doped Ce) were tested by using the etalons of alpha, beta and gamma radiation with low energies (241Am, 90Sr, 55Fe...) and a standard 222Rn. Those detectors have been developed in Crytur Ltd. For the measurement was used a specially built test assembly comprising encapsulated scintillation detector with calibrated photomultiplier fixed in a black, variable-volume test chamber. All measurements were conducted under precisely defined geometry. The MC 1256 analyzer was used in 256 channel configuration. The focus was on measurement and assessment of the tested detectors surface characteristics, in relation to the light output, spectral resolution capability and peak-background characteristics [1.2]. The tests included extended time period of monitoring related to impact absorption on the surface of detectors and energy calibration. The end result was the selection of the most suitable surface processing for the thin scintillation detectors. These detectors can be assembled into large area arrays, enabling the increase of the detection efficiency, especially for the Alpha activity measurement in radioactive aerosols. The major advantage of these scintillation detectors is their low production cost compared with semiconductor detectors.

Resume En 1999, en region Rhone-Alpes, dans le cadre de la surveillance de la resistance de S. pneumoniae aux antibiotiques, 35 meningites ont ete repertoriees. Un questionnaire retrospectif a ete adresse a chaque participant. Les CMI a la penicilline, l’amoxicilline et le cefotaxime determinees a l’aide de la galerie ATB-PNEUMO® ou E-test® et les antibiogrammes ont ete interpretes selon les recommandations du CA-SFM. Soixante-trois pour cent des meningites ont ete observees en automne/hiver. L’âge median etait de 38,1 ans (extremes : 1 mois–78 ans), le sex-ratio M/F a 2/5. Huit patients avaient recu des antibiotiques dans les 15 jours precedents ; 22 patients presentaient des facteurs de risque (4 breches, 3 OMA…) ; 23 patients ont ete transferes en reanimation. Les traitements antibiotiques ont ete une C3G + glycopeptide chez 15 des 16 enfants et chez 13 des 19 adultes conformement aux recommandations de consensus. Le diagnostic a ete fait sur l’examen direct du LCR dans 83 % des cas. Les hemocultures etaient positives dans 74,3 % des cas. Le pourcentage de PSDP etait de 48,6 %, avec 17,1 % de souches intermediaires a l’amoxicilline et 14,3 % au cefotaxime. La resistance au trimethoprime-sulfamethoxazole etait de 45,7 %, au chloramphenicol de 30 % et a la fosfomycine de 6,9 %. Toutes les souches etaient sensibles a la rifampicine et a la vancomycine. Parmi les 17 PSDP, 7 souches appartenaient au serotype 6 dont 6 chez les enfants. L’evolution a ete marquee par 7 deces (20 %), tous de sexe masculin, sans facteur de risque chez les 3 enfants ; 6 souches sur 7 etaient peni-S. Six patients (17 %) ont eu des sequelles auditives et/ou neurologiques. Cette etude montre que presque la moitie des souches isolees de meningites, en region Rhone-Alpes, sont de sensibilite diminuee a la penicilline et confirme la frequence des survenues de sequelles qui, comme les deces, ne sont pas lies a la resistance des souches aux antibiotiques.

Sensory characterisation of virgin olive oil is completely standardised in the European Union. The sensory profile used to evaluate samples is made up of 16 descriptors, three of them being generic. These three attributes [Other ripe fruit(s), Other positive attribute(s) and Other negative attribute(s)] could be of great additional interest in the characterisation of different samples. However, as they are not specifically defined it is difficult to reach a descriptor consensus among assessors evaluating the samples. This situation is similar to that produced when using a Free Choice Profile and so the Generalised Procrustes Analysis (GPA) could be extremely useful in obtaining all the information contained in these three generic descriptors. In this study GPA was applied to the descriptors generated by a 25 member expert panel under the headings Other ripe fruits and Other positive attributes when evaluating 11 samples of virgin olive oil from the variety ‘Arbequina’ grown in three different regions. The Generalised Procrustes Analysis was efficient in the sensory characterisation of the 11 samples studied using the information provided by the two positive generic descriptors included in the official sensory profile. The overall result was equivalent to that obtained using Correspondence Analysis, although the GPA gave more information since it also included the intensity of each of the descriptors and was less affected by odd descriptors. This technique was as useful in the characterisation of the samples as the other six positive descriptors defined in the official sensory profile (Olive fruity, Apple, Green, Sweet, Bitter, and Pungent), providing additional information of great scientific and commercial interest.

Objective – The authors wanted to determine the state of pneumococcus resistance in the Rhone-Alpes region, in 1999. Patients and method – One thousand eight hundred and thirteen strains of S. pneumoniae (Sp) (64.5% adults, 35.5% children) were collected by 31 clinical microbiological laboratories. Susceptibility to oxacillin of the strains (isolated in pathogenic conditions) was measured according to CA-SFM standards. The MICs of penicillin (P), amoxicillin (AMX), and cefotaxime (CTX) were determined (E-test or ATB-Pneumo gallery) for all strains resistant to penicillin G (PRP). The regional coordinating center checked the MIC and serotype of each PRP strain. Results – The prevalence of PRP (MIC > 0.06 mg/L) was 40.5%. Resistance (I + R) to ERY, TET, SXT, and C was respectively 42%, 27.4%, 37.9%, and 19.2%. Among the 9.4% of strains resistant to P (MIC > 1 mg/L), 63.3% were intermediate to AMX (0.5 2 mg/L). The multiresistance was frequent in PRP: 70.7% to ERY, 72% to TET, 45% to SXT, 32.8% to C, and only 0.4% to RIF. PRP of serotype 14 (23.8%) were the most frequent, followed by serotypes 6 (16%), 23 (15.7%), 9 (12%), 19 (11%), and 15 (2.8%). Discussion – PRP have been increasing since 1997 (29.5% vs. 40.5%), AMX-R strains are still infrequent (2%), and CTX-R strains even though rare (0.3%) are now isolated.

En 1999, dans le cadre de la surveillance de la resistance de S. pneumoniae aux antibiotiques, les 877 souches oxacilline < 26 mm (5 μg) ou de sensibilite diminuee a la penicilline (PSDP) ont fait l'objet d'une determination des CMI a trois β-lactamines par E-test® pour 220 souches, ou par ATB-PNEUMO® pour 657 souches dans les 31 centres collaborateurs de la region Rhone-Alpes. Ces souches etaient ensuite centralisees au site coordonnateur charge de determiner ces CMI par la technique de reference de dilution en milieu gelose. La concordance a ± 1 dilution des deux tests avec la technique de reference etait respectivement pour ATB-PNEUMO® et E-test® de 89% versus 84 % pour la penicilline (difference non significative), de 86% vs 79% pour l'amoxicilline (p < 0,01) et de 91 % vs 86% pour le cefotaxime (p = 0,03). Lors de la categorisation therapeutique, les differences etaient significatives (p < 0,001) pour amoxicilline (85 % vs 71 %) et cefotaxime (82 % vs 75 %) mais pas pour la penicilline (73 % vs 78 %). La methode de l'erreur standard avec transformation angulaire a ete utilisee pour comparer la sensibilite et la specificite des deux methodes lors de la categorisation therapeutique des souches. La methode ATB-PNEUMO® est plus sensible que le E-test® pour la detection des souches sensibles a P (90 vs 73%), a AMX (83 vs 78%) et au CTX (80 vs 72%) et pour les souches intermediaires a AMX (90 vs 78 %). Elle est aussi plus specifique que le E-test® pour les souches AMX-S (85 vs 53 %) et CTX-S (72 vs 42 %). En revanche, le E-test® est plus specifique que ATB-PNEUMO® pour la detection des souches Peni-R (94 vs 86 %). Le nombre de souches CTX-R etant trop restreint, la sensibilite et la specificite n'ont pu etre determinees. Enfin, la specificite des deux methodes est equivalente pour la detection des souches Peni-S, AMX-R et CTX-I.

Resume Objectif – Determiner l'etat de la resistance du pneumocoque en 1999 dans la region Rhone-Alpes. Patients et methodes – Mille huit cent treize souches de Streptococcus pneumoniae (64,5 % adultes, 35,5 % enfants) ont ete collectees par 31 laboratoires. La sensibilite a l'oxacilline des souches isolees en situation pathogene a ete mesuree (normes du CA-SFM). Pour toutes les souches de sensibilite diminuee a la penicilline G (PSDP), les CMI a la penicilline G, l'amoxicilline et au cefotaxime ont ete determinees (E-test ou ATB-Pneumo). Le centre coordinateur a controle la CMI ainsi que le serotypage des souches de PSDP. Resultats – La prevalence des PSDP etait de 40,5 %. Parmi les 9,4 % de resistants, 63,3 % etaient intermediaires a l'amoxicilline et 0,8 % resistants au cefotaxime. La resistance a l'erythromycine, tetracycline, cotrimoxazole, chloramphenicol, pristinamycine, rifampicine et fosfomycine etait de 42 %, 27,4 %, 37,9 %, 19,2 %, 1,4 %, 0,6 % et 8 %. La multiresistance chez les PSDP etait de : 70,7 % a l'erythromycine, 72 % a cotrimoxazole, 45 % a tetracycline, 32,8 % au chloramphenicol, 1,8 % a la pristinamycine et 0,4 % a la rifampicine. Les PSDP de serotypes 14 (23,8 %) etaient les plus frequents, puis les serotypes 6 (16 %), 23 (15,7 %), 19 (11 %), et 15 (2,8 %). Discussion – Depuis 1997 les PSDP augmentent (29,5 % versus 40,5 %), les souches resistantes a l'amoxicilline sont encore peu frequentes (2 %) et celles resistantes au cefotaxime (0,3 %) sont maintenant isolees.

Timepix is an evolving energy and position sensitive pixel detector. It consists of a silicon detector (sensitive layer 300 μm thick) bump-bonded to the Timepix readout chip developed by the Medipix2 collaboration. This study aims to test the feasibility of using the acquired energy and position signals from Timepix for positron imaging. The signals of the commonly used fluorine-18 PET (positron emission tomography) tracer [18F]FDG were measured using Timepix operated both in single particle counting (Medipix) and in time over threshold (TOT) modes. The spatial resolution (SR) was measured using the absorber edge method (AEM) and was calculated from the over-sampled line spread function. The track of a positron in the Timepix detector was characterized as a cluster and the energy weighted centroid of each cluster was considered as readout for the position of the positron incidence. The measurement results were compared with theoretical predictions using Monte-Carlo simulations. In addition, imaging of a tissue slice of a mouse heart was analysed with reference to standard phosphor plate imaging. Our results show that the SR was improved from 177.1±4.1 μm (centroid without energy weighting) to 155.5±3.1 μm μm (centroid with energy weighting). About 12% enhancement of SR was achieved with energy information in TOT mode. The sensitivity of Timepix was 0.35 cps/Bq based on the measurements. The measuring background and the ratio between detected positrons and gamma rays were also evaluated and were found to be consistent with theoretical predictions. A small enhancement of image quality was also achieved by applying energy information to the data of the measured tissue sample. Our results show that the inclusion of energy information could slightly enhance the positron measurement compared to without energy information and the Timepix provides a high SR and sensitivity for positron detection. Thus, Timepix is a potentially effective tool for 2D positron imaging.

Very thin scintillator imaging plates have recently become of great interest. In high resolution X-ray projection imaging, very thin scintillators of about 5-20 micrometres are used to achieve high spatial resolution. Such thin screens are mainly used in micro-CT and nano-CT systems with either micro-focus X-ray tubes or with synchrotron sources. This work deals with a high resolution CCD camera in connection with an optical system and different single crystal scintillators in application for low energy X-ray micro-radiography. The thin screens used were prepared by mechanical polishing from Y3Al5O12 or Lu3Al5O12 single crystals. The screens can be used in equipment for the detection of different kinds of radiation and particles (UV, VUV, electrons or ions or their beams, X- or gamma-rays). A high resolution open type micro-focus X-ray tube was used to achieve the high resolution. The results show that the single crystal plates exhibit high spatial resolution and high sensitivity to low energy X-rays resulting in high image contrast. The use of the plates is highly suitable for light weight (low Z) material X-ray radiography. The resolution achieved is demonstrated using a test grid. Several light weight objects are imaged using the thin plates.

Over the last decades the traditional photographic films used in radiology are being replaced by digital X-ray imaging sensors in many applications. The main advantages of these systems are their detection efficiency of image acquisition and the ability to directly digitally transfer and enhance obtained images. In this paper we characterize and evaluate the X-ray imaging performance of a YAG:Ce single crystal scintillator. The scintillator converts X-rays into visible light that is collected by an optical camera. The camera uses a CCD sensor with the size of 36x24 mm2 and with 4050 x 2630 pixels of 9x9 μm2 pitch, and is equipped with a macro objective. The semiconductor pixel detector Medipix2 was used for the evaluation of the imaging capabilities of this imaging system. The imaging capability is evaluated in terms of several basic characteristics: spatial resolution, edge response function, signal to noise ratio and contrast to noise ratio. A microfocus X-ray tube was used for high spatial resolution measurements in order to minimize the influence of the X-ray tube spot size. Measurements were done using an edge phantom, step wedge phantom and low contrast fibres. The corresponding measurements for all phantoms were done under identical conditions in order to assure comparability. The results measured by the CCD camera demonstrate the possibilities of sensitive X-ray radiography imaging with high spatial resolution.

A high resolution X-ray camera for micro-radiography is described and presented, consisting of a CCD detector and precise thin YAG:Ce or LuAG:Ce single crystal screens. Different applications and various results are described. The 2D-spatial resolution of an X-ray or other ionizing radiation imaging systems is one of the critical parameters in non-destructive microradiography and radiation beam inspection. The main goal of this work was to use the 2D-imaging system with different scintillation screens, and to compare the 2D-resolution in the micrometer range and sensitivity for low energy microradiography. These imaging systems can use various scintillation detectors. Specifically, thin YAG:Ce or LuAG:Ce single crystal screens are compared. Finally, the use of an X-ray CCD camera in imaging of small, light-weight biological objects is presented.

Screening by ofloxacin disk was carried out on 1158 strains of Streptococcus pneumoniae in order to investigate the in vitro bacteriostatic activity of penicillin G, levofloxacin, moxifloxacin, telithromycin, linezolid, pristinamycin and quinupristin–dalfopristin against ofloxacin-intermediate and -resistant S. pneumoniae strains. It was concluded that these new antimicrobial agents could be useful for the treatment of pneumococcal infections caused by penicillin-sensitive and -resistant S. pneumoniae, and would represent a valid therapeutic option for patients allergic to β-lactams, should they prove to be potent in vivo.

Staphylococcus aureus isolates were screened for reduced susceptibility to glycopeptides with an initial glycopeptide agar screening test, followed by confirmation of the strains thus identified by two Etest strip techniques and population analysis. This procedure detected 48 methicillin-resistant S. aureus (MRSA) isolates with reduced susceptibility to glycopeptides from 24 patients among 883 MRSA isolates tested. The dissemination of a single clone was confirmed by pulsed-field gel electrophoresis.