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Muon scattering tomography techniques can be used to image the contents of an enclosed volume by measuring the scattering angle of cosmic ray muons as they pass through a volume using particle tracking detectors. The magnitude of the observed muon scatter varies with the density of the objects within a volume, therefore the technique is well suited to distinguishing dense (high-Z) materials from lower...
Fast and accurate lost radioactive source positioning is of critical importance for the prevention of radiation damage in the accident. Traditional instruments with low detection efficiency cost lots pf time and energy, and may lead to harms to the operator's health. A portable detector to directly determine the incident angle of gamma rays is promising for the homeland security applications. In this...
In particle physics, tracking and vertexing typically relies on silicon strip or pixel detectors arranged in multiple planes. The ePix100a detector was developed for low noise x-ray detection. When used for high energy particle tracking and imaging, it yields a signal to noise ratio (SNR) of 500 to 1000. The unusually large SNR allows accurate reconstruction of tracks, down to subpixel resolution...
Dedicated brain PET has the potential to achieve better sensitivity, spatial resolution and image quality than conventional whole body PET cameras in brain tomography. Spherical PET (S-PET), that can achieve a higher geometrical sensitivity and a lower parallax error than conventional cylindrical ring PET scanners, is a good candidate for high performance dedicated brain imaging. Our simulation studies...
In image guided radiation therapy (IGRT), certain patient treatment positions can lead to collisions of the patient with the linac gantry. When such collisions arise, it prevents the gantry from rotating around the patient and acquiring sufficient projection information for current analytic-based reconstruction methods such as FDK. One way to alleviate such a collision would be to move the patient...
The easyPET concept proposed here, protected under a patent by the University of Aveiro, aims to realize a simple and affordable small dimension Positron Emission Tomography (PET) scanner. This innovative system is based on a single pair of detectors and a rotating mechanism with two degrees of freedom reproducing the functionalities of an entire PET ring. A 2D imaging prototype has been designed,...
Measuring system response matrix (SRM) by Monte Carlo method is time and resource consuming, even with high performance computer nodes. In this paper, we exploited symmetry properties available to drastically reduce the complexity in computing SRM of panel PET, which has two parallel panel detectors. By extending the original system and simulating 4 voxels every slice parallel to the PET detector,...
PTSIM is a particle therapy system simulation framework based on Geant4 Monte Carlo simulation toolkit. It was originally developed as a reliable dose calculation tool to verify dose distributions inside patient and dose calculation algorithms in treatment planning systems. Besides such a reliable dose calculation, an irradiation field monitoring is desirable for delivering dose with more ideal distribution...
A Compton Camera (CC) prototype is currently being commissioned at the Ludwig-Maximilians-Universität München. It is planned to be used for studying in-vivo proton or ion beam range monitoring capabilities by means of prompt gamma (PG) rays, exploiting Compton scattering kinematics in order to reconstruct a PG based image correlated to the beam range. The camera consists of a monolithic LaBr3(Ce)...
We are currently developing a dual-particle imager based on the rotational modulation collimator (RMC) technique employing Cs2LiYCl6:Ce (CLYC) detector. A symmetric mask design has been conventionally used for RMC, however, it has an intrinsic problem of not being able to distinguish two symmetric sources located with respect to the rotation axis. In the present study, we propose a new design of collimator...
We have developed a method to restore the image obtained by the pinhole camera, which allows to increase the angular resolution by about 3-4 times and to obtain uniform sensitivity in the all field of view without a noticeable increase in noise in the gamma-ray image. The method is based on the use of the inverse problem solution for finding the distribution of incident photons with the measured apparatus...
In compact systems, precise measurement in the projection space may be compromised due to minification. The objective of this work is to investigate the impact of the magnification factor in a model-based calibration procedure. This has direct relevance to the geometrical calibration of the clinical INSERT camera. Projection data from three point sources were simulated for a single pinhole collimator...
Gamma-ray imaging allows for efficient detection, characterization, and localization of compact radioactive sources in cluttered environments. Fieldable detector systems employing active planar coded masks demonstrate broad energy sensitivity via both coded aperture and Compton imaging modalities. Because planar configurations suffer from a limited field-of-view, we introduce a novel design by rearranging...
The benefit of time-of-flight (TOF) in PET reconstruction has been established for clinical imaging, and the signal-to-noise benefit with TOF has been demonstrated to increase with higher randoms fractions. TOF information mitigates and reduces image artifacts arising from errors in the corrections, but it may not account for all changes with count rate. Standard performance measures of image quality...
The next generation of organ specific Positron Emission Tomography (PET) scanners, e.g. for breast imaging, will use partial ring geometries. We propose a component-based Maximum-Likelihood (ML) estimation of normalisation factors for 3D PET data reconstruction applicable to partial ring geometries. This method is based on the Software for Tomographic Image Reconstruction (STIR) for full ring PET...
Within the German Plant Phenotyping Network (DPPN), we developed a novel PET scanner based on Philips Digital Photon Counters (DPCs, or dSiPMs = digital Silicon Photomultipliers). The scanner is dedicated for plant research and provides functional information on carbon transport within the plant. To this end the detector ring is oriented horizontally. It provides a Field-of-View of 18 cm dia. and...
In this work we perform a preliminary investigation of a discretized natural pixel expansion set for image representation in optimization-based image reconstruction for X-ray computed tomography. In particular, we focus our attention on total variation regularized image reconstruction in pixel and discrete natural pixel expansion sets. The work is motivated by two observations: (1) under certain conditions,...
Single-Plane Compton Imaging is introduced as a novel scheme of gamma-ray imaging that might overcome basic drawbacks of conventional Anger cameras. It replaces passive collimation by kind of a “soft” electronic collimation based on the Compton kinematics. In contrast to Compton cameras, where individual scattering angles are determined event-by-event from coincident energy depositions in separate...
We have characterized a PET prototype based on monolithic scintillator detectors. The prototype has a modular design with 8 identical detector cassettes, each housing 4 monolithic blocks. The cassettes are mounted on a gantry in 2 groups of 4 cassettes facing each other, totaling 32 detectors. Each detector block is composed of a trapezoidal LYSO:Ce scintillator glued to a pair of Hamamatsu S8550-02...
The availability of synchrotron-generated high-flux and high-energy x-rays has significantly reduced the acquisition time a tomographic scan which allows following dynamic processes in 4D (3D space + time). In the ultra-fast endstation usually a scintillator is used to convert X-ray to visible photons that can be detected by the camera. However, this conversion is not ideal and the scintillator decays...
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