33 research outputs found
A compact PC-based X-ray imaging system
No full textA compact, portable PC-based X-ray imaging system has been developed based on a 2D silicon microstrip sensor and particle physics readout electronics. The sensor is housed. in a specially built hybrid, which also hosts the front-end electronics. The control and the readout electronics used are based on the standard PCI and PMC architectures and were originally developed for High Energy Physics Experiments. The use of PCI based electronics and the development of the control software for the PC-Linux platform led to a compact, portable, low cost imaging system. The system was initially tested and evaluated with beta particles from a (90)Sr radioactive source, gamma rays from an (241)Am radioactive source and cosmic rays, and it displayed consistent response. It was then operated using a compact X-ray machine with Mo tube and images of various targets were reconstructed offline using the ROOT data analysis package. (c) 2006 Elsevier B.V. All rights reserved.Nuclear Instruments & Methods in Physics Research Section a-Accelerators Spectrometers Detectors and Associated Equipmen
A Multi-Element Detector System for Intelligent Imaging: I-ImaS
No full textI-ImaS is a European project aiming to produce new, intelligent x-ray imaging systems using novel APS sensors to create optimal diagnostic images. Initial systems concentrate on mammography and encephalography. Later development will yield systems for other types of radiography such as industrial QA and homeland security.
The I-ImaS system intelligence, due to APS technology and FPGAs, allows real-time analysis of data during image acquisition, giving the capability to build a truly adaptive imaging system with the potential to create images with maximum diagnostic information within given dose constraints.
A companion paper deals with the DAQ system and preliminary characterization. This paper considers the laboratory x-ray characterization of the detector elements of the I-ImaS system. The characterization of the sensors when tiled to form a strip detector will be discussed, along with the appropriate correction techniques formulated to take into account the misalignments between individual sensors within the array.
Preliminary results show that the detectors have sufficient performance to be used successfully in the initial mammographic and encephalographic I-ImaS systems under construction and this paper will further discuss the testing of these systems and the iterative processes used for intelligence upgrade in order to obtain the optimal algorithms and setting
Performance of Si sensors irradiated to 5 x 10(14) n/cm(2)
No full textThe expected particle fluence in the inner part of the CMS Preshower is calculated to be 1.6 x 10(14) cm(-2) for neutrons and 0.4 x 10(14) cm(-2) for charged hadrons. Since the error of the calculation is high and/or unexpected accidental beam misalignments might happen we have irradiated Preshower silicon sensors to fluences up to 5 x 10(14) n/cm(2) to verify that they hold voltages necessary to reach the full charge collection efficiency. All irradiated sensors showed no signs of breakdown up to 1000 V, the maximum voltage applied. All but one display a sufficiently stable charge collection efficiency up to 1000 V. No noisy channels were observed at the extreme voltages. The measured charge collection efficiency was 71 +/- 12% and 59 +/- 12% for sensors irradiated to 3 x 10(14) and 5 x 10(14) n/cm(2), respectively. These values are consistent with the extrapolation from previous measurements made on sensors irradiated to 2.3 x 10(14) n/cm(2) The work presents the results of static and dynamic measurements and shows that our design and the technology are very robust. (C) 2003 Elsevier B.V. All rights reserved.Nuclear Instruments & Methods in Physics Research Section a-Accelerators Spectrometers Detectors and Associated Equipmen
Design, synthesis and biological evaluation of stereo- and regioisomers of amino aryl esters as multidrug resistance (MDR) reversers
No full textStereo- and regioisomers of a series of N,N-bis(alkanol)amine aryl ester derivatives have been prepared and studied as multidrug resistance (MDR) modulators. The new compounds contain a 2-(methyl)propyl chain combined with a 3-, 5- or 7-methylenes long chain and carry different aromatic ester portions. Thus, these compounds have a methyl group on the 3-methylenes chain and represent branched homologues of previously studied derivatives. The introduction of the methyl group gives origin to a stereogenic center and consequently to (R) and (S) enantiomers. In the pirarubicin uptake assay on K562/DOX cell line these compounds showed good activity and efficacy and in many cases enantioselectivity was observed. Docking studies confirmed the influence of the stereocenter on the interaction in the P-gp pocket. The P-gp interaction mechanism and selectivity towards MRP1 and BCRP were also evaluated on MDCK transfected cells overexpressing the three transporters. Almost all these compounds inhibited both P-gp and BCRP, but only derivatives with specific structural characteristics showed MRP1 activity. Moreover, two compounds, (S)-3 and (R)-7, showed the ability to induce collateral sensitivity (CS) against MDR cells. Therefore, these two CS-promoting agents could be considered interesting leads for the development of selective cytotoxic agents for drug-resistant cells
A scanning system for intelligent imaging: I-ImaS.
No full textI-ImaS (Intelligent Imaging Sensors) is a European project aiming to produce adaptive x-ray imaging systems using Monolithic Active Pixel Sensors (MAPS) to create optimal diagnostic images. Initial systems concentrate on mammography and cephalography. The on-chip intelligence available to MAPS technology will allow real-time analysis of data during image acquisition, giving the capability to build a truly adaptive imaging system with the potential to create images with maximum diagnostic information within given dose constraints. In our system, the exposure in each image region is optimized and the beam intensity is a function not only of tissue thickness and attenuation, but also of local physical and statistical parameters found in the image itself. Using a linear array of detectors with on-chip intelligence, the system will perform an on-line analysis of the image during the scan and then will optimize the X-ray intensity in order to obtain the maximum diagnostic information from the region of interest while minimizing exposure of less important, or simply less dense, regions. This paper summarizes the testing of the sensors and their electronics carried out using synchrotron radiation, x-ray sources and optical measurements. The sensors are tiled to form a 1.5D linear array. These have been characterised and appropriate correction techniques formulated to take into account misalignments between individual sensors. Full testing of the mammography and cephalography I-ImaS prototype is now underway and the system intelligence is constantly being upgraded through iterative testing in order to obtain the optimal algorithms and settings. In preliminary simulations the dose savings between the regulated images and the reference images were estimated to between 30 to 70%
Preliminary images from an adaptive imaging system
No full textI-ImaS (Intelligent Imaging Sensors) is a European project aiming to produce real-time adaptive X-ray imaging systems using Monolithic Active Pixel Sensors (MAPS) to create images with maximum diagnostic information within given dose constraints. Initial systems concentrate on mammography and cephalography. In our system, the exposure in each image region is optimised and the beam intensity is a function of tissue thickness and attenuation, and also of local physical and statistical parameters in the image. Using a linear array of detectors, the system will perform on-line analysis of the image during the scan, followed by optimisation of the X-ray intensity to obtain the maximum diagnostic information from the region of interest while minimising exposure of diagnostically less important regions. This paper presents preliminary images obtained with a small area CMOS detector developed for this application. Wedge systems were used to modulate the beam intensity during breast and dental imaging using suitable X-ray spectra. The sensitive imaging area of the sensor is 512 × 32 pixels 32 × 32 μm2 in size. The sensors' X-ray sensitivity was increased by coupling to a structured CsI(Tl) scintillator. In order to develop the I-ImaS prototype, the on-line data analysis and data acquisition control are based on custom-developed electronics using multiple FPGAs. Images of both breast tissues and jaw samples were acquired and different exposure optimisation algorithms applied. Results are very promising since the average dose has been reduced to around 60% of the dose delivered by conventional imaging systems without decrease in the visibility of details. Keywords: X-ray imaging; Intelligent imaging; CMOS; Mammography; Adaptive imagin
