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Nodule detection is a vital step in computer-aided diagnosis (CAD) system, for its accuracy can greatly influence the reliability of the system. Many researchers have proposed lots of effective filters to detect nodules. However, these filters have limitations, such as changing the nodules shapes and sizes. This paper proposes a modified Difference of Gaussian (DoG) detector for pulmonary nodule location...
A new portable gamma-ray imaging spectroscopy system using three dimensional position-sensitive CdTeZe has been built at the University of Michigan. This system uses a first generation digital VAD_UM ASIC jointly developed by Integrated Detector Electronics AS (IDEAS) and the University of Michigan and allows four 20 × 20 × 15 mm3 CdZnTe detectors to be simultaneously read out in either a full readout...
Nonlinearity in the output signals for the energy deposited by gamma-ray interactions can seriously degrade the energy resolution of a pixellated detector when the signals from more than one pixel are summed to get the total deposited energy. Such nonlinearity can be calibrated on a pixel-by-pixel basis by using multiple gamma-ray check sources of various known energy photopeaks for gamma-ray energy...
Polaris-H, a compact Compton camera designed by H3D, Inc. has been characterized and tested in field measurements at nuclear power plants. Polaris-H integrates a 3D-position-sensitive pixelated CZT detector (20 mm × 20 mm × 15 mm), associated readout electronics, an embedded computer, a 5-hour battery, and an optical camera all within a portable water-resistant case. The total mass is about 4 kg....
In pixelated CdZnTe (CZT) detectors, multiple interaction gamma-ray events are critical because they permit Compton imaging. However, in large-volume CZT crystals, the depth of multiple interaction events are often poorly reconstructed due to significant nonuniformity of electron drift velocity while the depth of single interaction events can be accurately reconstructed using signal ratios. The electron...
In this paper we addresses the problem of human action recognition by introducing a new representation of image sequences as a collection of spatiotemporal events that are localized at interest point and using multi-class SVM for classification. The interest points are detected by the SIFT detector and a spatio-temporal interest point detector. We proposed a new bag of words approach to represent...
In this paper, we introduce an improved version of DAISY descriptor algorithm, which is used for high-quality image keypoint matching. Since DAISY descriptor algorithm has many prominent advantages but lacks the ability of handling large in-plane rotation, we thus construct our Rotation-Invariant DAISY descriptor to effectively settle this shortcoming. The matching results of our scheme can be also...
The Polaris system is an array of 18 position-sensitive detectors, using 6 cm3 pixelated CdZnTe crystals from Redlen Technologies and readout electronics from Gamma-Medica Ideas (GMI). Many detectors received from Redlen Technologies are capable of achieving 1% energy resolution or better at 662 keV for all single-pixel events during room temperature operation. Furthermore, 3D position reconstruction...
An experiment to measure the performance of 3-D position-sensitive pixellated HgI2 crystals cooled below room temperature was carried out using a new ASIC from GammaMedica-Ideas. This ASIC is capable of reading out the digitized pre-amplifier signal waveforms of 121 pixels and the cathode. A significant improvement in energy resolution from 1.48% FWHM at 662keV for the whole detector to 1.09% FWHM...
This work investigate the full energy and total efficiencies of large volume CdZnTe detectors. The efficiencies of three 20 mm × 20 mm × 15 mm pixelated CdZnTPe detectors were measured using the H3Dv2 Application Specific Integrated Circuit (ASIC) readout system developed by Brookhaven National Laboratory with un-collimated 241Am, 137Cs, and 60Co sources. One detector was made by eV-Products while...
There's great influence on the reconstructed image by X-ray scatter in cone-beam computed tomography (CBCT). X-ray scatter correction technique is one of the hot research fields in 3D imaging of CBCT. A hybrid scatter correction method is proposed, which combines the beam attenuation grid and the beam stop block. Combined with the scatter correction equipments, a scatter correction algorithm is designed...
Due to the steering grid that aids the collection of electrons by the anode pixels, the common-grid pixelated CdZnTe (CZT) detectors have demonstrated better performance than simple pixel detectors. For a detailed analysis of charge sharing and weighting potential cross-talk that occurs near and underneath the gap and energy resolution degradation in common-grid CZT detectors, a detailed detector...
A 3-dimensional position-sensitive CdZnTe gamma-ray detector employs a pixellated anode (11 ?? 11 pixels) and a planar cathode on a 15 ?? 15 ?? 10 mm3 or 20 ?? 20 ?? 15 mm3 CdZnTe single crystal. The signals from the 121 pixels and the cathode read out by Application Specific Integrated Circuits (ASIC) are used to reconstruct the energy depositions and 3-D coordinates of multiple gamma-ray interactions...
The depth of interaction in pixelated CdZnTe and HgI2 detectors is determined using either the cathode-to-anode signal ratio (CAR) or drift time information. The CAR can be used if a ??-ray interacts only once in the detector. The drift time must be used if the ??-ray interacts over multiple pixels. The accuracy of these reconstruction techniques is evaluated using a collimated fan beam of ??-rays...
The observed energy resolution of pixellated wide band-gap semiconductor detectors degrades as the number of triggered pixels increases. For multiple pixel events, one of the biggest barriers to overcome during the energy reconstruction is the effects of weighting potential cross-talk. The current calibration method determines a set of correction coefficients to convert each measured signal to an...
In this paper a novel detecting device based on movable contactless conductivity detector was described. The stainless steel mould replaces the silicon and nickel mould to fabricate the capillary electrophoresis chip and overcome the disadvantage of complicated technology and frangibility. The parameters of hot embossing were optimized. In the paper a sandwich electrode structure was proposed. The...
Three-dimensional-position-sensitive CdZnTe detectors have excellent energy resolution along with imaging capability. In this work, a 2 cm × 2 cm × 1.5 cm CdZnTe detector was used to detect shielding in front of sources. By using the energy-imaging integrated spectral deconvolution (EIID) algorithm, the shielding has a unique signature in the reconstructed image.
The signals from 3-D position-sensitive pixellated CdZnTe (CZT) detectors have been modeled for the VAS_UM/TAT4 ASIC readout electronics. Each detector has dimensions of 20 mm × 20 mm × 15 mm, with an 11 × 11 square pixel anodes fabricated on the anode surface having a pixel pitch of 1.72 mm. Gamma-ray interactions with detector material, charge drift, charge trapping and diffusion, signal induction,...
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