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In a smart home system, a camera-based fall detector at elderly homes leads to immediate alarming and helping. In this paper we propose an approach for the detection of falls based on multiple cameras. Based on semantic driven features, fall detection is done in 3D and fuzzy logic is used to estimate confidence values for different human postures as well as for the incidence of a fall/no fall. Emphasis...
Due to its capability of maximizing the embedded information from a large amount of medical images captured from different imaging modalities and acquired from different scanning intervals, medical image registration plays an essential role in clinical applications including diagnosis, radiotherapy planning, assessment of patient's response to the treatment. An intensive research on registration methodologies...
68Ga is one of the non-conventional nuclides that are being used in preclinical imaging. One disadvantage of 68Ga versus 18F is its larger positron range, which deteriorates the effective spatial resolution and the overall image quality. In this work we present a performance evaluation of the ARGUS small-animal positron emission tomography (PET) scanner for two positron emitters, 68Ga and 18F. These...
Multi-pinhole collimation is increasingly being used in SPECT imaging. A wide variety of geometric designs has recently been introduced, which can easily be modeled with the Monte Carlo simulator GATE. However multi-pinhole simulations are still very inefficient with GATE due to the lack of a dedicated variance reduction technique. In this work, we introduced a pinhole forced detection method which...
We evaluate the performance of a large field-of-view gamma camera (9.5mm thick NaI(Tl) crystal) connected to a new 80-channel list-mode read out system. The final goal of this setup is its use for simultaneous sub-mm imaging of positron emitters (511keV) and single photon emitting tracers (25-400keV) in a small animal scanner. All of the 55 photomultiplier tubes (PMT) in our test gamma camera have...
Positron emission tomography (PET) detectors based on monolithic scintillation crystals show excellent intrinsic spatial resolution and allow depth-of-interaction (DOI) reconstruction using a single photosensor array. The inclusion of time-of-flight (TOF) information in the image reconstruction significantly reduces the image noise variance, effectively increasing the PET system sensitivity. For optimal...
AX-PET is a novel PET concept based on long crystals axially arranged and orthogonal Wavelength shifter (WLS) strips, both individually readout by Geiger-mode Avalanche Photo Diodes (G-APD). Its design was conceived in order to reduce the parallax error and simultaneously improve spatial resolution and sensitivity. The assessment of the AX-PET concept and potential was carried out through a set of...
The aim of this work is to develop a high spatial resolution, high sensitivity, compact PET detector for small animal PET/MR imaging. The key design features are the use of trapezoidal slat crystals (TSC), the use of silicon photomultiplier (SiPM) arrays, and the use of a 3D statistics based positioning (SBP) algorithm. Through simulation, the performance of a detector module consisting of 8 trapezoidal...
A Compton camera is an imaging system for three-dimensional (3D) distribution of gamma emitting sources based on Compton scattering interaction. The measurement error on energies and positions directly leads to uncertainties on the formation of cones and degrades the spatial resolution of the reconstructed images. Mostly the limited energy resolution, Doppler broadening and position segmentation of...
Iterative methods are currently accepted as the gold standard image reconstruction methods in nuclear medicine. The quality of the final reconstructed image greatly depends on how good the physical processes are modelled in the System-Response-Matrix (SRM). Monte-Carlo based methods are a promising approach to calculate the SRM. However, the increasing granularity used in the detector and image space...
With the continual improvement in spatial resolution of Nuclear Medicine (NM) scanners, it has become increasingly important to accurately compensate for patient motion during acquisition. Respiratory motion produced by lung ventilation is a major source of artefacts in NM that can affect large parts of the abdominal-thoracic cavity. As such, a particle filter (PF) is proposed as a powerful method...
Subject motion during PET data acquisition reduces the achievable resolution. Methods to correct PET data for motion often use external motion tracking devices, for example with commercial Infrared based cameras. Accurate spatial and temporal alignment between the Infrared camera and PET or PET/CT is essential. Here we propose a simple and robust method for direct identification in PET image space...
Parallax error in PET modules can be reduced by measuring the annihilation photon depth of interaction (DOI) in the scintillation crystal on an event-by-event basis. Following implementations described in prior literature, we selected a dual-sided readout PET module design in which SiPMs are placed at both ends of a scintillation array and the ratio of the signal from one photodetector (A) divided...
Early clinical results with time-of-flight (TOF) PET systems have demonstrated the advantages of TOF information in PET reconstruction. Reconstruction approaches in TOF-PET systems include list-mode and binned iterative algorithms as well as confidence-weighted analytic methods. List-mode iterative TOF reconstruction retains the full accuracy of the data in the spatial and temporal domains but is...
With modern cardiac CT scanners detection and classification of coronary artery diseases is a common task. More and more low dose cardiac CT prevails the clinical routine. To suppress noise, a smooth reconstruction kernel is used. Unfortunately this inducts an additional blurring to the images. At high contrast graduations this so-called blooming makes it hard to identify small structures especially...
The ECAT High Resolution Research Tomograph (HRRT) is a dedicated human brain PET camera with a 6% absolute sensitivity and a (2.3mm)3 spatial resolution, improving to (1.8mm)3 when point spread function (PSF) resolution recovery algorithms are used. These values are very close to those of the dedicated small animal PET camera microPET FOCUS 120 (F120). The larger axial and transaxial FoV of the HRRT...
A way to improve the spatial resolution in positron emission tomography (PET) is to determine the depth-of-interaction (DOI) in the detector which can be achieved by using the phoswich approach. The depth identification is done by using differences in scintillation decay time and pulse shape discrimination techniques. The advantages of the concept have been demonstrated in the HRRT high resolution...
The current study aimed to derive accurate estimates of regional cerebral blood flow (rCBF) from noisy dynamic [15O]H2O PET images acquired on the High Resolution Research Tomograph (HRRT), whilst retaining the high spatial resolution of this scanner (2-3 mm) in parametric images. We compared the PET autoradiographic and the generalised linear least squares (GLLS) methods to the non-linear least squares...
We demonstrate the capability of one detector, the Micro-Angiographic Fluoroscope (MAF) detector, to image for two types of applications: nuclear medicine imaging and radiography. The MAF has 1024 × 1024 pixels with an effective pixel size of 35 microns and is capable of real-time imaging at 30 fps. It has a CCD camera coupled by a fiber-optic taper to a light image intensifier (LII) viewing a 300-micron...
This article presents the performance evaluation in planar and tomographic mode, of a low cost dedicated PET camera for small animal imaging. The system consists of two pixelated LSO crystals, two Hamamatsu H8500 PSPMTs, fast amplification electronics and a FPGA based read out system. The main parameters that have been studied are i) saturation as a function of acceptance angle ii) effect of projections...
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