10,367 research outputs found
Time resolution of the plastic scintillator strips with matrix photomultiplier readout for J-PET tomograph
Recent tests of a single module of the Jagiellonian Positron Emission
Tomography system (J-PET) consisting of 30 cm long plastic scintillator strips
have proven its applicability for the detection of annihilation quanta (0.511
MeV) with a coincidence resolving time (CRT) of 0.266 ns. The achieved
resolution is almost by a factor of two better with respect to the current
TOF-PET detectors and it can still be improved since, as it is shown in this
article, the intrinsic limit of time resolution for the determination of time
of the interaction of 0.511 MeV gamma quanta in plastic scintillators is much
lower. As the major point of the article, a method allowing to record
timestamps of several photons, at two ends of the scintillator strip, by means
of matrix of silicon photomultipliers (SiPM) is introduced. As a result of
simulations, conducted with the number of SiPM varying from 4 to 42, it is
shown that the improvement of timing resolution saturates with the growing
number of photomultipliers, and that the 2 x 5 configuration at two ends
allowing to read twenty timestamps, constitutes an optimal solution. The
conducted simulations accounted for the emission time distribution, photon
transport and absorption inside the scintillator, as well as quantum efficiency
and transit time spread of photosensors, and were checked based on the
experimental results. Application of the 2 x 5 matrix of SiPM allows for
achieving the coincidence resolving time in positron emission tomography of
0.170 ns for 15 cm axial field-of-view (AFOV) and 0.365 ns
for 100 cm AFOV. The results open perspectives for construction of a
cost-effective TOF-PET scanner with significantly better TOF resolution and
larger AFOV with respect to the current TOF-PET modalities.Comment: To be published in Phys. Med. Biol. (26 pages, 17 figures
Multichannel FPGA based MVT system for high precision time (20~ps~RMS) and charge measurement
In this article it is presented an FPGA based ulti-oltage hreshold
(MVT) system which allows of sampling fast signals ( ns rising and falling
edge) in both voltage and time domain. It is possible to achieve a precision of
time measurement of ps RMS and reconstruct charge of signals, using a
simple approach, with deviation from real value smaller than 10.
Utilization of the differential inputs of an FPGA chip as comparators together
with an implementation of a TDC inside an FPGA allowed us to achieve a compact
multi-channel system characterized by low power consumption and low production
costs. This paper describes realization and functioning of the system
comprising 192-channel TDC board and a four mezzanine cards which split
incoming signals and discriminate them. The boards have been used to validate a
newly developed Time-of-Flight Positron Emission Tomography system based on
plastic scintillators. The achieved full system time resolution of
(TOF) ps is by factor of two better with respect to the
current TOF-PET systems.Comment: Accepted for publication in JINST, 10 pages, 8 figure
J-PET analysis framework for the prototype TOF-PET detector
Novel TOF-PET scanner solutions demand, apart from the state of the art
detectors, software for fast processing of the gathered data, monitoring of the
whole scanner and reconstruction of the PET image. In this article we present
an analysis framework for the novel STRIP-PET scanner developed by the J-PET
collaboration in the Institute of Physics of the Jagiellonian University. This
software is based on the ROOT package used in many particle physics
experiments.Comment: 4 pages, 2 figure
J-PET Framework: Software platform for PET tomography data reconstruction and analysis
J-PET Framework is an open-source software platform for data analysis,
written in C++ and based on the ROOT package. It provides a common environment
for implementation of reconstruction, calibration and filtering procedures, as
well as for user-level analyses of Positron Emission Tomography data. The
library contains a set of building blocks that can be combined by users with
even little programming experience, into chains of processing tasks through a
convenient, simple and well-documented API. The generic input-output interface
allows processing the data from various sources: low-level data from the
tomography acquisition system or from diagnostic setups such as digital
oscilloscopes, as well as high-level tomography structures e.g. sinograms or a
list of lines-of-response. Moreover, the environment can be interfaced with
Monte Carlo simulation packages such as GEANT and GATE, which are commonly used
in the medical scientific community.Comment: 14 pages, 5 figure
Determination of the map of efficiency of the J-PET detector with the GATE package
A novel PET detector consisting of strips of polymer scintillators is being
developed by the J-PET Collaboration. The map of efficiency and the map of
geometrical acceptance of the 2-strip J-PET scanner are presented. Map of
efficiency was determined using the Monte Carlo simulation software GATE based
on GEANT4. Both maps were compared using method based on the chi2 test.Comment: 14 pages, 9 figures, proceeding from conference Symposium on Positron
Emission Tomography: http://koza.if.uj.edu.pl/pet-symposium-2013
The Integration of Positron Emission Tomography With Magnetic Resonance Imaging
A number of laboratories and companies are currently exploring the development of integrated imaging systems for magnetic resonance imaging (MRI) and positron emission tomography (PET). Scanners for both preclinical and human research applications are being pursued. In contrast to the widely distributed and now quite mature PET/computed tomography technology, most PET/MRI designs allow for simultaneous rather than sequential acquisition of PET and MRI data. While this offers the possibility of novel imaging strategies, it also creates considerable challenges for acquiring artifact-free images from both modalities. This paper discusses the motivation for developing combined PET/MRI technology, outlines the obstacles in realizing such an integrated instrument, and presents recent progress in the development of both the instrumentation and of novel imaging agents for combined PET/MRI studies. The performance of the first-generation PET/MRI systems is described. Finally, a range of possible biomedical applications for PET/MRI are outlined
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