ABSTRACT
The proposed analysis considers aspects of both statistical and biological validation of the glycolysis effect on brain gliomas, at both genomic and metabolic level. In particular, two independent datasets are analyzed in parallel, one engaging genomic (Microarray Expression) data and the other metabolomic (Magnetic Resonance Spectroscopy Imaging) data. The aim of this study is twofold. First to show that, apart from the already studied genes (markers), other genes such as those involved in the human cell glycolysis significantly contribute in gliomas discrimination. Second, to demonstrate how the glycolysis process can open new ways towards the design of patient-specific therapeutic protocols. The results of our analysis demonstrate that the combination of genes participating in the glycolytic process (ALDOA, ALDOC, ENO2, GAPDH, HK2, LDHA, LDHB, MDH1, PDHB, PFKM, PGI, PGK1, PGM1 and PKLR) with the already known tumor suppressors (PTEN, Rb, TP53), oncogenes (CDK4, EGFR, PDGF) and HIF-1, enhance the discrimination of low versus high-grade gliomas providing high prediction ability in a cross-validated framework. Following these results and supported by the biological effect of glycolytic genes on cancer cells, we address the study of glycolysis for the development of new treatment protocols.
Subject(s)
Brain Neoplasms/metabolism , Glioma/metabolism , Brain Neoplasms/genetics , Cluster Analysis , Computational Biology/methods , Databases, Factual , Gene Expression Profiling , Glioma/genetics , Glycolysis , Humans , Magnetic Resonance Spectroscopy , Metabolome , Support Vector MachineABSTRACT
In this study, measurements of the electrical and detection parameters of the Cd1-xZnxTe detectors, within the x-ray diagnostic energy range, have been performed with the aim of optimizing the image quality parameters of these solid-state-ionization detectors. Namely, the leakage current and system capacitance of the x-ray imaging system have been measured as they relate to signal parameters. Similarly, the detected signal and noise contributions were measured and related to the radiation exposure and tube current setting. Furthermore, the detector contrast has been experimentally determined. The experimental results indicate that Cd1-xZnxTe detectors have low leakage current, high resistivity, and high detector contrast resolution. Therefore, they appear to be very attractive for imaging applications with applications in x-ray digital radiography.
ABSTRACT
In this study, the electric field dependence on the charge collection process of CdZnTe detectors, at different x-ray tube settings, within the x-ray diagnostic energy range, is investigated. In addition, the detector contrast at different applied bias voltages and x-ray tube settings have been experimentally determined. The experimental results suggest that an efficient charge collection process is obtained by increasing the applied bias voltage. Once the applied bias voltage is sufficiently high, charge collection becomes complete and the detector operates in the saturation region. This is a prerequisite for high contrast and spatial resolution. As a result, the detector contrast is enhanced significantly. Therefore, CdZnTe detectors appear to be potential candidates for digital radiographic applications.
ABSTRACT
CdZnTe is one of the most promising semiconductor material in the field of digital X-ray imaging, and may be operated at room temperature. To improve the detector characteristics, ternary systems such as Cd1-xZnxTe were grown by the high pressure Bridgman (HPG) technique. The signal performance characteristics of quasi-resistive Cd1-xZnxTe semiconductor detectors, was studied at different directions of irradiation, within the X-ray diagnostic energy range. The experimental results suggest that the total efficiency of these semiconductor detectors depends upon the energy absorption efficiency as well as the charge collection efficiency. This imaging detector allows one to investigate methods to improve the detection and imaging performance parameters as part of the development of an X-ray imaging system.
ABSTRACT
Radiographic studies with the aim of optimizing the imaging potential of Cd1-xZnxTe detectors for digital chest radiography have been performed. A geometrical chest phantom has been designed, and the dependence of both the signal-to-noise ratio and contrast resolution of a planar Cd1-xZnxTe detector on the phantom thickness has been experimentally determined. Specifically, the detected signal and noise contributions were measured and related to phantom thickness. The results of this study indicate that Cd1-xZnxTe detectors exhibit both high signal-to-noise ratio and contrast resolution. At present time, several studies are in process to experimentally identify and quantify the imaging potential of Cd1-xZnxTe detectors for digital radiographic applications.
ABSTRACT
Experiments have been performed with the aim of optimizing the image quality parameters of CdZnTe detectors for digital mammography. A geometrical breast phantom has been designed, and the dependence of the contrast resolution of a planar CdZnTe detector on the phantom thickness has been experimentally determined. Specifically, the detected signal and noise contributions were measured and related to phantom thickness. The results of this study indicate that the CdZnTe detectors exhibit a high contrast resolution. On the other hand, the dynamic range of this detector can be improved significantly by further implementation of the data acquisition electronics.
ABSTRACT
The goal of this study is to develop high resolution imaging detectors with applications in digital radiography and computed tomography. A physical treatment aimed at a better understanding of the line-spread function response of kinestatic charge detector (KCD) gas media, using dopants with permanent electric dipoles, is presented. Experimental results were obtained by operating a KCD krypton-filled detector at pressures up to 60 atm and constant electric field-to-gas density ratio doped with small amounts of polar or nonpolar polyatomic molecules with low or high ionization potential. The results clearly indicate that the addition of dopants having both low ionization potential and high dipole moment significantly enhance the imaging signal quality. An analysis of the experimental results aimed at providing a plausible interpretation of the reported observations is offered.
ABSTRACT
A systematic study of the line spread function (LSF) in the drift direction of a high-pressure ionization chamber for x-ray detection and imaging is presented. Experimental results, obtained by operating a KCD krypton-filled detector at pressures up to 60 atm and constant electric field-to-gas pressure ratio, indicate that the width of the LSF increases with the drift distance and decreases with increasing pressure, both effects being quite large. The hypothesis of this paper is that, at sufficiently high pressures, formation of clusters of molecular ions with a unique or narrowed mobility distribution take place by means of energy exchange mechanisms. Therefore, the LSF of the ionic signal becomes narrower and the FWHM of the ionic signal improves significantly with increasing gas pressure. This research is aimed at investigating methods to improve the spatial resolution as part of the development of a large field-of-view prototype digital radiographic scanner operating on kinestatic charge detection principles.
ABSTRACT
The engineering aspects of a nine-channel digital radiographic system developed for bioimaging research, based on high gas pressure ionography and kinestatic principles, are presented. The research imaging system uses a pulsed x-ray beam which allows one to study simultaneously the ionic signal characteristics at 10 different ionization sites along the drift axis. This research imaging detector system allows one to investigate methods to improve the detection and image quality parameters as part of the development of a large scale prototype medical imaging system.
