Qualification Procedures of the CMS Pixel Barrel Modules

The CMS pixel barrel system will consist of three layers built of about 800 modules. One module contains 66560 readout channels and the full pixel barrel system about 48 million channels. It is mandatory to test each channel for functionality, noise level, trimming mechanism, and bump bonding quality. Different methods to determine the bump bonding yield with electrical measurements have been developed. Measurements of several operational parameters are also included in the qualification procedure. Among them are pixel noise, gains and pedestals. Test and qualification procedures of the pixel barrel modules are described and some results are presented.Comment: 7 Pages, 7 Figures. Contribution to Pixel 2005, September 5-8, 2005, Bonn, Germna

Diagnostic and interventional radiology: a strategy to introduce reference dose level taking into account the national practice

The purpose of this study is to present a strategy to define the reference dose levels for fluoroscopic, dose-intensive examinations. This work is a part of the project of the Federal Office of Public Health of Switzerland to translate the guidelines of the International Commission on Radiological Protection and the European Union into action. The study will also be used to set reference dose levels on the basis of a national survey. All the fluoroscopic units, involved in the survey, were equipped with a KAP (kerma-area product) meter. All KAP meters were first calibrated to ensure the comparability of the dose measurements. The doses and the dose rates together with subjective image quality measurements were acquired in all the centres. Eight types of examination were chosen by a panel of radiologists, and each of the five centres involved agreed to monitor 20 patients per examination type. A wide variation in the dose and the image quality in fixed geometry was observed. For example, the skin dose rate for abdominal examinations varied in the range of 12-42 mGy min−1 for comparable image quality. Average KAP values of 67, 178, 106, 102, 473, 205, 307 and 316 Gy cm2 were recorded for barium meal, abdominal angiography, cerebral angiography, barium enema, hepatic embolisation, biliary drainage, cerebral embolisation and femoral stenting, respectively. The values obtained in this limited study are generally higher than the ones available in the literature and strategies to optimise these studies have to be discussed. A strict control concerning the denomination of the examination type involved in such a study is mandatory to obtain reliable data. This can only be done through a close collaboration between physicians, radiographers and medical physicist

Criteria for establishing shielding of multi-detector computed tomography (MDCT) rooms

The aim of this work is to compare two methods used for determining the proper shielding of computed tomography (CT) rooms while considering recent technological advances in CT scanners. The approaches of the German Institute for Standardisation and the US National Council on Radiation Protection and Measurements were compared and a series of radiation measurements were performed in several CT rooms at the Lausanne University Hospital. The following three-step procedure is proposed for assuring sufficient shielding of rooms hosting new CT units with spiral mode acquisition and various X-ray beam collimation widths: (1) calculate the ambient equivalent dose for a representative average weekly dose length product at the position where shielding is required; (2) from the maximum permissible weekly dose at the location of interest, calculate the transmission factor F that must be taken to ensure proper shielding and (3) convert the transmission factor into a thickness of lead shielding. A similar approach could be adopted to use when designing shielding for fluoroscopy rooms, where the basic quantity would be the dose area product instead of the load of current (milliampere-minute

Strategien zur Reduktion der CT-Strahlendosis

Zusammenfassung: Die rasante technische Weiterentwicklung der CT hat in den letzten Jahren zu einer deutlichen Zunahme der diagnostischen Möglichkeiten geführt, mit dem Resultat, dass die CT-Untersuchungszahlen weltweit angestiegen sind. Dies hat ebenfalls Auswirkung auf die Strahlenexposition der Bevölkerung. Bis heute sind zahlreiche Publikationen erschienen, die gezeigt haben, dass eine Dosisreduktion erreicht werden kann, ohne dadurch die Bildqualität und Sensitivität der CT zu beeinträchtigen. Die Mehrzahl der Strategien zur Dosisoptimierung sind einfach anzuwenden und unabhängig von der Detektorkonfiguration des CT-Scanners. Im vorliegenden Übersichtsartikel werden die wichtigsten Methoden vorgestellt: indikationsabhängige Methoden (z.B. rechtfertigende Indikation, Reduktion der Röhrenspannung für die CT-Angiographie, Wahl von Kollimation und Pitchfaktor, Minimierung der Untersuchungsphasen, Senkung der Röhrenspannung und des -stroms für die Nativphase), herstellerabhängige Methoden (z.B. automatische Röhrenstrommodulation, adaptive Filter zur Reduktion des Bildrauschens, iterative Bildrekonstruktion) und allgemeine Methoden (z.B. Patientenzentrierung im Isozentrum der CT-Gantry, Reduktion der Scanlänge, Anwendung von Röntgenschutzmitteln, Reduktion der Röhrenspannung und/oder des -stroms für den CT-Planungsscan

Adult reference levels in diagnostic and interventional radiology for temporary use in Switzerland

This work aims at establishing a set of diagnostic reference levels (DRLs) for various types of examinations performed in diagnostic and interventional radiology. The average doses for 257 types of radiological examinations were established during the 1998 nationwide survey on the exposure of the Swiss population by radiodiagnostics. They were calculated using appropriate dosimetric models and average technical parameters. The DRLs were derived from the average doses using a multiplying factor of 1.5. The DRLs obtained were rounded and compared to the data reported in the literature. The results are in most cases comparable to the DRLs determined by the 3rd-quartile method. These discrepancies registered in some cases, particularly for complex examinations, can be explained by significant differences in the protocols and/or the technical parameters used. A set of DRLs is proposed for a large number of examinations to be used in Switzerland as temporary values until a national dosimetric database is set u

Improved count rate corrections for highest data quality with PILATUS detectors

A Monte Carlo simulation is presented, which computes the rate correction factors taking into account the detector settings and the time structure of the X-ray beam. The results show good agreement with experimentally determined correction factors

Skull diversity and evolution in miniaturized amphibians, genus Brachycephalus (Anura: Brachycephalidae)

Miniaturized amphibians of the genus Brachycephalus are phenotypically diverse. The species of Brachycephalus have bufoniform or leptodactyliform baupläne and any of three skeletal states: nonhyperossified, hyperossified without dorsal shield, and hyperossified with dorsal shield. We integrate high-resolution microcomputed tomography, geometric morphometrics, and an estimate of molecular phylogenetic relationships to investigate skull diversity in shape and size-shape space in selected species of Brachycephalus. Skull diversity amongst species of Brachycephalus can be partitioned into shape and size-shape space according to the four conditions of skeletal states-baupläne, namely, nonhyperossified leptodactyliform, nonhyperossified bufoniform, hyperossified bufoniform without dorsal shield, and hyperossified bufoniform with dorsal shield. Skull diversity in shape and size-shape space in nonhyperossified leptodactyliform species of Brachycephalus is markedly larger, when compared to skull diversity in species of the three other conditions of skeletal states-baupläne. Variation in skull shape scales with size across Brachycephalus and, therefore, can be explained by allometry. Skull diversity, baupläne, and skeletal states covary to a large extent with monophyletic lineages of Brachycephalus, as revealed by a mitochondrial DNA species tree. Nonhyperossified bufoniform species and hyperossified bufoniform species with or without dorsal shield are monophyletic lineages, as inferred from a mitochondrial DNA species tree. Nonhyperossified leptodactyliform species of Brachycephalus do not share, however, a most recent common ancestor. The nonhyperossified leptodactyliform species of Brachycephalus, due to their marked skull diversity and lack of monophyly, emerge as evolutionarily complex. Therefore, further sampling of the nonhyperossified leptodactyliform condition of skeletal states-baupläne will be necessary to further understand the evolutionary history of Brachycephalus.Fil: dos Reis, Sérgio F.. Universidade Estadual de Campinas. Instituto de Biología; BrasilFil: Clemente Carvalho, Rute B.G.. Queens University; CanadáFil: dos Santos, Caio M. S. F. F.. Universidade Federal do Rio de Janeiro; BrasilFil: Lopes, Ricardo T.. Universidade Federal do Rio de Janeiro; BrasilFil: Von Zuben, Fernando J.. Universidade Estadual de Campinas; BrasilFil: Laborda, Prianda R.. Universidade Estadual de Campinas. Instituto de Biología; BrasilFil: Perez, Sergio Ivan. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata; Argentina. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Departamento Científico de Antropología; Argentin

EXPOSURE OF THE SWISS POPULATION BY RADIODIAGNOSTICS: 2013 REVIEW.

In 2013, a nationwide investigation was conducted in Switzerland to establish the population's exposure from medical X rays. A hybrid approach was used combining the Raddose database accessible on-line by the participating practices and the Swiss medical tariffication system for hospitals. This study revealed that the average annual number of examinations is 1.2 per inhabitant, and the associated annual effective dose is 1.4 mSv. It also showed that computed tomography is the most irradiating modality and that it delivers 70 % of the total dose. The annual effective dose per inhabitant registered a 17 % increase in 5 y and is comparable with what was recently reported in neighbouring countries