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Many recent interferometric and tomographic SAR algorithms aimed at enhancing the monitoring performances on distributed areas affected by decorrelation phenomena have been proposed in the last years. These algorithms are based on the exploitation of the data covariance matrix, estimated on real data through the coherent averaging of statistically similar pixels, to improve signal-to-noise ratio and...
The effectively large mirror size in a space telescope may be achieved by swarms of mirrors. In this paper, we present an analysis of such a space telescope, where a swarm of randomized micro-mirrors are combined to achieve the resolution comparable to a primary mirror equivalent to the entire distribution. The recorded speckle patterns, which vary randomly in time, are transformed into a high resolution...
The Canny algorithm has been extensively adopted to perform edge detection in images. The Derivative of Gaussian (DoG) proposed by Canny has been shown to be the optimal edge detector to compute the image gradient due to its robustness to noise. However, the DoG has some important drawbacks in relation to images with thin edges of a few pixels width and junctions. The excessive blurring provided by...
This paper presents a method that combines the background subtraction with the Viola-Jones face detector to detect human faces from video sequence captured by a fixed camera. We use a texture based method for background subtraction to extract foreground sub-images for the face detector. It allows the detector to focus on face detection on smaller image regions and thereby reduces its computational...
In this paper, we implement a facial landmarking system to improve the performance of landmark location accuracy for the tree-structured based facial detector proposed recently by Zhu and Ramanan. Our main objective is to overcome their limitation where very small faces could not be detected and landmarked. Furthermore, we also want to improve the landmarking accuracy and reduce false positive rate...
In high resolution CT image reconstruction, a proper geometrical model is beneficial for achieving high quality images. This work aimed to improve CT image resolution with OSC (Ordered Subset Convex) reconstruction algorithm by incorporating a geometric model for the finite-size of CT detector pixels.
A combination of Monte Carlo (MC) and deterministic approaches was employed as a means of creating a simulation tool capable of providing energy resolved x-ray primary and scatter images within a reasonable time interval. Libraries of Sindbad, a previously developed x-ray simulation software, were used in the development. A cross-validation of the method against an analog MC (EGS4) simulation and...
We are developing a Point-Of-Care PET (POC-PET) imaging system platform that consists of one or more movable probe detectors in coincidence with a detector-array behind a patient. The probes are hand movable so that the operator can control the probe trajectory freely to achieve optimal coverage and sensitivity for patient-specific imaging tasks. This platform does not require a conventional full...
The authors have implemented the Maximum Likelihood Expectation Maximization (MLEM) algorithm using Graphic Processing Units (GPU) and multiple cores (CPU) for the reconstruction of high spatial resolution positron emission tomography (PET) images. The massive amount of computation involved in precalculated system matrix limits the application of the MLEM reconstruction algorithm in practice, so the...
The EndoTOFPET-US collaboration develops a novel multimodal device for Ultrasound (US) Endoscopy and Positron Emission Tomography (PET) for detecting and quantifying novel morphologic and functional biomarkers for pancreas and prostate oncology. The detector is based on scintillating crystals with Silicon Photomultiplier (SiPM) read-out, aiming at a time of flight coincidence time resolution of 200...
Recently DOI detection technologies have been rapidly developed for pre-clinical and clinical PET systems. Lack of DOI detection capability will result in serious LOR location deviation and image resolution degradation due to the detector parallax effect. Based on theoretically analyzing the probability distribution function of the DOI information, this study proposed four analytical DOI estimation...
This work presents an effective algorithm to identify crystal element positions for the design and operation of practical PET imaging detectors capable of achieving both excellent time resolution required for time-of-flight (ToF) and depth-of-Interaction (DoI) information. The detector unit consists of a dual layer (LYSO:Ce and LSO:Ce,Ca(0.4%)) stack of two 3×3×10 mm3 crystals, 1∶1 coupled to SiPM...
Nowadays, time-of-flight (TOF) PET detectors and systems are becoming increasingly common since scintillators, photodetectors and electronics has made significant progress. It has been well recognized that TOF PET imaging can increase the image signal-to-noise ratio (SNR) and yield other benefits; and the degree of these enhancements is higher as the timing resolution improves. Previously we have...
Small animal and clinical SPECT cameras based on multi-pinhole detector arrangements typically boast spatial resolutions of 1–2mm and 4mm respectively. However, directional variability of the local imaging capability within the field-of-view (FOV) can impact our ability to detect abnormalities. We aimed to demonstrate the dependence of resolution on object position and orientation within the FOV in...
The key to reaching SPECT's full diagnostic potential lies in optimizing the imaging geometry to maximize the system geometric efficiency (SGE) at a given resolution. The optimal geometry differs for different imaging applications, for different imaging tasks within a single application, and for different patients. The C-SPECT cardiac SPECT/Tct platform unifies innovative sub-systems in a cardiocentric...
We propose a new method for modeling the detector module crystal positioning-blur and mis-positioning errors based on the detector modules' flood histograms (crystal position map) and crystal segmentation maps and use simulations for validation. First, a statistical simulation tool is used to simulate signal pathways from gamma photons in crystals to photo-multiplier tube pulses and then to digitized...
In this research, we compared the performance of a CZT Compton PET and those of conventional micro-PETs using scintillators in which Compton tracing technology was applied. The conventional micro-PETs used photoelectric interaction only as effective events for PET image reconstruction and their position resolution are limited by the size of a single scintillator voxel. The CZT Compton PET, however,...
In recent years, multi-pixel photon counters (MPPCs) have been actively studied for use in a module for such next-generation PET systems as MRI-PET, DoI-PET, and ToF-PET scanners. In particular, Time of Flight (ToF) measurement is a challenging approach to identify the position of a γ-ray source, according to differences in the arrival times of annihilation γ rays after positron decay. Several simulations...
Reducing the number of readout channels of PET detectors with multiplexing can save the cost and complexity for developing a scanner. However, a high multiplexing ratio can also degrade the signal-to-noise (SNR) ratio of the detector since the noise of the multiplexed channels is summed together. Compressed sensing (CS) was recently shown to be a promising multiplexing method for PET detectors that...
This work presents the design of scintillation detectors for clinical PET using off-the-shelf components that achieve both excellent time resolution and DoI information. The detector consists of a dual layer stack of 3×3×20 mm3 crystals, 1∶1 coupled to SiPM arrays. Each pixel contains an LYSO:Ce and LSO:Ce,Ca(0.4%) crystal directly bonded to one another with an optical epoxy, and layer identification...
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