The Infona portal uses cookies, i.e. strings of text saved by a browser on the user's device. The portal can access those files and use them to remember the user's data, such as their chosen settings (screen view, interface language, etc.), or their login data. By using the Infona portal the user accepts automatic saving and using this information for portal operation purposes. More information on the subject can be found in the Privacy Policy and Terms of Service. By closing this window the user confirms that they have read the information on cookie usage, and they accept the privacy policy and the way cookies are used by the portal. You can change the cookie settings in your browser.
Dynamic CT could provide a relatively inexpensive and widely available technique to measure myocardial blood flow (MBF) for evaluating coronary artery disease (CAD). The main limitation to clinical acceptance is the substantial radiation dose. The dose can be reduced by decreasing the photon flux or the number of temporal frames, both resulting in noisy 4D data from which accurate MBF information...
MP-JRM performs better in situations where JRM and MRI-IR under-perform. This is because MP-JR relies on both MRI and PET data, whereas JRM and MRI-IR rely on one modality only. In addition, results tend to show that with temporal smoothing on B-spline parameters, a subset of MRI volumes gives enough information to compensate for motion. Further work is in progress to analyse variance and bias as...
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...
For the first time, we propose using amorphous selenium (a-Se) as the photoconductive material for time-of-flight (TOF) detectors. The major drawback of a-Se is its poor time-resolution and low mobility due to shallow-traps, problems that must be circumvented for TOF applications. Thus, we propose a nanopattern multi-well a-Se detector to enable the utilization of both avalanche multiplication gain...
In this work we study the non-proportionality of CsI(X) (X=Tl, Na) determined for fast and slow light components, separately. The studies are a continuation of previous measurements of non-proportionality characteristics obtained for fast and slow components of the light pulse of NaI(Tl) at room temperature. Simple experimental technique, applied in this work, allowed for measuring the light pulse...
The crystal Cs2LiYCl6:Ce (CLYC) is a very interesting scintillator material because of its excellent energy resolution and its capability to identify gamma rays and fast/thermal neutrons. In this work, the response to gamma, thermal and fast neutrons of two CLYC 1“x1” crystals was measured: the first one, enriched with 6Li at 95% is ideal for thermal neutron measurements while the second one, enriched...
An analytical model is presented to show the mechanisms of the electric field and temperature dependent effective drift mobility of holes in amorphous selenium (a-Se) considering the density of states distribution, thermally activated tunneling for the field enhancement release rate, and carrier heating. In addition, the model for the field-dependent microscopic mobility considering carrier heating...
Proton therapy facilities use high-energy proton beams to destroy cancerous cells. In this approach, secondary radiation is produced due to proton interactions with the patient and surrounding materials. This secondary radiation field, which includes both neutrons and photons, must be accurately characterized in order to determine its effect on patients and medical personnel. The MCNPX-PoliMi code...
A geometrical model to describe the annihilation positions associated with scattered coincidences has been proposed in this study. This model can accurately describe the distribution of the annihilation positions in a normalized coordinate, which can be used to further improve the reconstructed image quality in a scattering reconstruction algorithm.
We developed a SiPM based MR-compatible DOI-TOF-PET detector. The detector consists of a scintillator block, a light guide, a 64-channels SiPM array, and front-end electronics (FEE) boards. The scintillator block consists of 2.9 mm × 2.9 mm × 20 mm LGSO crystals in a 16 × 16 array containing light reflectors arranged for four-layer DOI encoding by Anger logic calculation. The FEE including a full-custom...
We proposed to explore extremely fast digital switching devices used in telecommunications for use as photon counting, energy resolving x-ray detectors. The HEMT (High Electron Mobility Transistor), used in ultra-fast switches and low noise amplifiers, offers a very low noise and high frequency operation. For this study a HEMT-based photon-counting energy-resolving ultra-fast x-ray detector with improved...
A compact Detector Module for Time-Of-Flight PET integrating 128 gamma-ray detection pixels of 3.5×3.5×15 mm3 LYSO crystals associated to MPPC photosensors has been developed in the framework of the EndoTOFPET-US collaboration. The module has two 64-channel readout ASICs integrating signal conditioning and discrimination circuitry and high-performance TDCs for each channel, featuring 25 ps r.m.s intrinsic...
Reliable interpretation of results from pre-clinical Emission Tomography studies is often hampered by the requirement that the animal be anesthetised, affecting certain neuro-transmission systems and cerebral blood flow. Animal tracking and motion compensation techniques have been exploited to account for that rigid motion associated with head movement - allowing brain imaging in small animals. However,...
In positron emission tomography (PET) imaging, scattered gamma photons typically account for more than 30% of total detected coincidence counts. Single scatter simulation (SSS) method is widely used for estimating scatter contribution in PET image reconstruction. Monte Carlo (MC) techniques are more accurate but computationally expensive. When using SSS, the modeled scatter contribution is typically...
Cone beam artifacts are commonly observed in volumetric CT images reconstructed by use of filtered backprojection method such as Feldkamp algorithm when the cone angle is relatively large and bony structures are present, for example in the head imaging task. In this work, we try to answer the question “Is it possible to suppress cone beam artifacts using iterative reconstruction algorithms in circular...
Absolute quantification from cardiac single photon emission computerized tomography (SPECT) remains challenging due to the complication of heterogeneous background and extracardiac radioactivity, causing a substantial estimation error in the quantification of radiotracer uptake in the heart. The partial volume effect resulted from the limited SPECT resolution is another confounding source contributing...
Depth-of-interaction measurement is essential for PET to reduce the parallax error, resulting in improved spatial resolution with maintaining sensitivity. One of ultimate goals of improvement in DOI detectors is achieving isotopic spatial resolution. For this purpose, we have developed an isotropic 3D position sensitive PET detector named X'tal cube. The X'tal cube is composed of a scintillation crystal...
We investigate iterative image reconstruction strategies for clinical I-123 DaTscan imaging on a dual-headed mixed collimator SPECT system consisting of fan and multi-pinhole (MPH) collimators on separate heads. DaTscan is used for the diagnosis and monitoring progression of Parkinson's Disease (PD). The current system was proposed in [1] for high-resolution imaging of activity in the structures of...
Regularization methods are commonly used for noise reduction in SPECT image reconstruction. Total variation (TV) is a well-accepted method for suppressing noise while preserving edges. However, using TV as regularizer implies that the image is piecewise constant. Usually this is untrue in clinical settings and leads to staircasing artifacts. High-order TV (HOTV) and infimal-convolution TV (ICTV) are...
Scatter correction is an essential data correction in quantitative PET imaging. In this work, a prototype of single scatter simulation using fast Monte-Carlo method (MC-SSS) for scatter estimate scaling instead of tail fitting was evaluated concurrently with the existing single-scatter simulation (SSS) algorithm. Reconstructions with both MC-SSS and SSS were performed on phantom and patient data collected...
Set the date range to filter the displayed results. You can set a starting date, ending date or both. You can enter the dates manually or choose them from the calendar.