In the 1990s, CEA has developed a very compact operational gamma camera, CARTOGAM, capable of mapping the surrounding radioactivity and representing it superimposed onto a visible-light image. Since ...then, the camera has been successfully industrialized and commercialized. In the same time, the Kurchatov Institute has developed a coded-aperture gamma camera. Both teams have joined their efforts to develop a compact coded-aperture gamma camera. This paper presents the first results obtained with a coded mask adapted to the existing CARTOGAM camera. Simulations have been carried out to design small-sized coded masks for high-energy gamma imaging (/sup 137/Cs or /sup 60/Co). Innovative tungsten-alloy masks have been achieved that lead to the following results: a significant increase in the sensitivity (up to 10 times), an improved angular resolution (2/spl deg/ to 3/spl deg/) and a large field of view (about 30/spl deg/). The laboratory results of /sup 137/Cs and /sup 60/Co imaging, including shadowgrams and reconstructed images for point sources, are presented.
We have developed a compact gamma-imaging system, CARTOGAM, for remote localisation of radioactive sources in nuclear facilities. This system is under industrial development and commercialisation by ...the firm EURISYS Mesures. The most specific characteristics of CARTOGAM lie in its size (8
cm in diameter) and mass (15
kg for the detection head, including the shield), which make it portable by a person. As an example, CARTOGAM detects a 660
keV source producing a 0.4
μGy/h dose rate at the camera location in 10
min. The angular resolution at that energy ranges from 1° to 3°, depending on the field of view (30° or 50°) and scintillator thickness (2 or 4
mm). We present here a review of the specifications of the camera and show a few images illustrating its performance.
Abstract
BACKGROUND
Multicentric glioblastoma (m-GBM), defined as well separated tumoral foci, is a rare GBM variant comprising 6–13% of all GBM cases. Published data regarding m-GBM is scarce and is ...largely reporting on multicentric enhancing foci. We performed a retrospective study to determine the incidence, imaging characteristics, treatment approach, pattern of relapse and prognosis of m-GBM.
MATERIAL AND METHODS
The neuropathological database of our institution was surveyed for histological diagnosis of adult GBM diagnosed between 01/01/2015 and 31/05/2018. All pre-operative MRI were reviewed to identify patients with m-GBM. We included in the definition of m-GBM well separated enhancing as well as non-enhancing tumor foci. The medical records and follow-up MRI studies were reviewed in order to retrieve the data.
RESULTS
Of the 170 patients with newly diagnosed GBM 14 (8%) presented with m-GBM. All of them had at least one enhancing lesion and 11 (78.5%) patients had additional well separated non-enhancing tumor foci. The total number of lesions was 37 (19 enhancing and 18 non-enhancing) with a median number of lesions per patient of 2 (range 2 to 4). Median age at diagnosis was 66 (range: 49–79) years. Nine of the patients (64%) underwent surgical resection of the enhancing component whereas 5 patients had only a biopsy. Median follow up was 14.3 (range: 2–30) months. All but one patients were treated by standard concurrent radiotherapy with temozolomide. Median progression free survival is 6.2 (range: 0–13.3) months. Five of the 18 non-enhancing tumor foci eventually displayed contrast enhancement during the course of the disease. At last follow up, 12 patients died, with an overall survival of 12.3 months. Information regarding radiation fields, pattern of disease progression and molecular profile will be presented at the meeting.
CONCLUSION
m-GBM presents therapeutic dilemas regarding the optimal surgical approach and radiation field planning. Better understanding of the disease course and pattern of progression may help to optimize the therapeutic approach implying particularly to non-enhancing tumor foci.
This study was designed to examine the differential effects of three types of adult interaction with kindergarten children using computers on children's cognitive performance and style of response. ...The types of adult interaction considered were: (1) mediation: provision of mediation, including behaviors such as focusing, affecting, expanding, encouraging, and regulation of behavior; (2) accompaniment: responding to children's questions; and (3) no assistance: provision of minimal technical assistance. The study sample included 150 kindergarten children, age 5–6 years. Children who engaged in adult-mediated computer activity showed higher levels of performance on a series of cognitive measures and more reflective response styles as compared to the other children. Adults' mediating behaviors found most predictive of children's cognitive performance were expanding, encouraging and regulation of behavior. Findings led to the conclusion that integrating adult mediation in pre-school computer learning environments facilitates informed use of computer technologies and has positive effects on children's performance.
Oxygen is the ultimate source of oxidizing power for disulfide bond formation, suggesting that under limiting oxygen proper protein folding might be compromised. We show that secretion of vascular ...endothelial growth factor (VEGF), a protein with multiple disulfide bonds, was indeed impeded under hypoxia and was partially restored by artificial increase of oxidizing equivalents with diamide. Physiologically, the oxireductase endoplasmic reticulum oxidoreductin-1 (Ero1)-L alpha, but not other proteins in the relay of disulfide formation, was strongly upregulated by hypoxia and independently by hypoglycemia, two known accompaniments of tumors. Further, we provide genetic evidence that induction of Ero1-L alpha by hypoxia and hypoglycemia is mediated by the transcription factor hypoxia-inducible factor 1 (HIF-1) but is independent of p53. In natural human tumors, Ero1-L alpha mRNA was specifically induced in hypoxic microenvironments coinciding with that of upregulated VEGF expression. To establish a physiological relevance to modulations in Ero1-L alpha levels, we showed that even a modest, two- to three-fold reduction in Ero1-L alpha production via siRNA leads to significant inhibition of VEGF secretion, a compromised proliferation capacity and enhanced apoptosis. Together, these findings demonstrate that hypoxic induction of Ero1-L alpha is the key adaptive response in a previously unrecognized HIF-1-mediated pathway that operates to improve protein secretion under hypoxia and might be harnessed for inhibiting tumor growth via inhibiting VEGF-driven angiogenesis.
We have grown 4 inch GaAs epitaxial layers of thickness ranging from 100 to 600 /spl mu/m. With such layers we made pixel X-ray detectors where each pixel is a p/sup +//i/n/sup +/ mesa structure in ...which the grown layer is the i region. The aim of this communication is to describe, prior to the evaluation of an image, the performances of such a detector in terms of homogeneity, reverse dark current, linearity, response time, dynamic range and charge collection efficiency. We shall also describe how the current induced by 100 kV X-rays in a detector made of a 115-/spl mu/m thick GaAs layer compares with that produced in the same conditions by a 1-mm thick CdTe detector.
Inevitably, viruses depend on host factors for their multiplication. Here, we show that hepatitis C virus (HCV) RNA translation and replication depends on Rck/p54, LSm1, and PatL1, which regulate the ...fate of cellular mRNAs from translation to degradation in the 5'-3'-deadenylation-dependent mRNA decay pathway. The requirement of these proteins for efficient HCV RNA translation was linked to the 5' and 3' untranslated regions (UTRs) of the viral genome. Furthermore, LSm1-7 complexes specifically interacted with essential cis-acting HCV RNA elements located in the UTRs. These results bridge HCV life cycle requirements and highly conserved host proteins of cellular mRNA decay. The previously described role of these proteins in the replication of 2 other positive-strand RNA viruses, the plant brome mosaic virus and the bacteriophage Qss, pinpoint a weak spot that may be exploited to generate broad-spectrum antiviral drugs.
The CARTOGAM portable gamma camera has been developed for gamma imaging applications in nuclear facilities. Its most remarkable characteristics are its mass (15 kg for the detection head, including ...the shield) and its size (8 cm in diameter and 40 cm in length), which make it very easy to handle. Another specificity of this camera lies in the fact that the same detector is used for both visible and gamma images, which warrants a precise correspondence between both images. The industrialisation of CARTOGAM has been performed by the firm Eurisys Mesures, and the camera is now commercially available. We present here the technical characteristics and the performance of this device. Images obtained during acquisition campaigns on various nuclear sites are reported. Finally we address some additional developments that improve the camera performance and the exploitation of the images, such as image segmentation, estimate of dose rates, as well as the use of the detector in a photon counting mode.
The CARTOGAM portable gamma camera, of particularly compact size (8 cm in diameter, 15 kg including the shielding), has been developed for gamma-imaging applications in nuclear facilities. The ...detector is composed of a CsI(Tl) scintillator, an image intensifier, and a charge-coupled device (CCD) matrix. The ordinary mode for image acquisition with such a detector is based on integration, and the main sources of noise in this mode are the photocathode thermoelectronic emission and the CCD pixels that have an abnormally high leakage current. We have developed an alternative acquisition mode based on a morphological processing of the elementary images at the video frequency (25 Hz). In this mode, gamma events are individually identified and the noise due to erratic thermoelectrons or white pixels is efficiently filtered, thus leading to an important gain in sensitivity. We present here experimental results obtained in this photon-counting mode in terms of signal-to-noise ratio (SNR), spatial resolution, saturation limit in dose rate, and sensitivity. A comparison is made with the integration mode. We also present a brief analysis of the problem of measuring the SNR on real images.
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