21 research outputs found
Estimating the NEMA characteristics of the J-PET tomograph using the GATE package
The novel whole-body PET system based on plastic scintillators is developed
by the {J-PET} Collaboration. It consists of plastic scintillator strips
arranged axially in the form of a cylinder, allowing the cost-effective
construction of the total-body PET. In order to determine properties of the
scanner prototype and optimize its geometry, advanced computer simulations
using the GATE software were performed.
The spatial resolution, the sensitivity, the scatter fraction and the noise
equivalent count rate were estimated according to the NEMA norm as a function
of the length of the tomograph, number of the detection layers, diameter of the
tomographic chamber and for various types of the applied readout. For the
single-layer geometry with the diameter of 85 cm, strip length of 100 cm,
cross-section of 4 mm x 20 mm and silicon photomultipliers with the additional
layer of wavelength shifter as the readout, the spatial resolution (FWHM) in
the centre of the scanner is equal to 3 mm (radial, tangential) and 6 mm
(axial). For the analogous double-layer geometry with the same readout,
diameter and scintillator length, with the strip cross-section of 7 mm x 20 mm,
the NECR peak of 300 kcps was reached at 40 kBq/cc activity concentration, the
scatter fraction is estimated to about 35% and the sensitivity at the centre
amounts to 14.9 cps/kBq. Sensitivity profiles were also determined
High Precision Axial Coordinate Readout for an Axial 3-D PET Detector Module using a Wave Length Shifter Strip Matrix
We describe a novel method to extract the axial coordinate from a matrix of long axially oriented crystals, which is based on wavelength shifting plastic strips. The method allows building compact 3-D axial gamma detector modules for PET scanners with excellent 3-dimensional spatial, timing and energy resolution while keeping the number of readout channels reasonably low. A voxel resolution of about 10 mm3 is expected. We assess the performance of the method in two independent ways, using classical PMTs and G-APDs to read out the LYSO (LSO) scintillation crystals and the wavelength shifting strips. We observe yields in excess of 35 photoelectrons from the strips for a 511 keV gamma and reconstruct the axial coordinate with a precision of about 2.5 mm (FWHM)
Simulating NEMA characteristics of the modular total-body J-PET scanner -- an economic total-body PET from plastic scintillators
The purpose of the presented research is estimation of the performance
characteristics of the economic Total-Body Jagiellonian-PET system (TB-J-PET)
constructed from plastic scintillators. The characteristics are estimated
according to the NEMA NU-2-2018 standards utilizing the GATE package. The
simulated detector consists of 24 modules, each built out of 32 plastic
scintillator strips (each with cross section of 6 mm times 30 mm and length of
140 cm or 200 cm) arranged in two layers in regular 24-sided polygon
circumscribing a circle with the diameter of 78.6 cm. For the TB-J-PET with an
axial field-of-view (AFOV) of 200 cm, a spatial resolutions of 3.7 mm
(transversal) and 4.9 mm (axial) are achieved. The NECR peak of 630 kcps is
expected at 30 kBq/cc activity concentration and the sensitivity at the center
amounts to 38 cps/kBq. The SF is estimated to 36.2 %. The values of SF and
spatial resolution are comparable to those obtained for the state-of-the-art
clinical PET scanners and the first total-body tomographs: uExplorer and
PennPET. With respect to the standard PET systems with AFOV in the range from
16 cm to 26 cm, the TB-J-PET is characterized by an increase in NECR
approximately by factor of 4 and by the increase of the whole-body sensitivity
by factor of 12.6 to 38. The TOF resolution for the TB-J-PET is expected to be
at the level of CRT=240 ps (FWHM). For the TB-J-PET with an axial field-of-view
(AFOV) of 140 cm, an image quality of the reconstructed images of a NEMA IEC
phantom was presented with a contrast recovery coefficient (CRC) and a
background variability parameters. The increase of the whole-body sensitivity
and NECR estimated for the TB-J-PET with respect to current commercial PET
systems makes the TB-J-PET a promising cost-effective solution for the broad
clinical applications of total-body PET scanners.Comment: 31 pages, 11 figures, 6 tables, submitted to Physics in Medicine and
Biology 202
Realistic Total-Body J-PET Geometry Optimization -- Monte Carlo Study
Total-Body PET is one of the most promising medical diagnostics modalities.
The high sensitivity provided by Total-Body technology can be advantageous for
novel tomography methods like positronium imaging. Several efforts are ongoing
to lower the price of the TB-PET systems. Among the alternatives, the
Jagiellonian PET (J-PET) technology, based on plastic scintillator strips,
offers a low-cost alternative. The work aimed to compare five Total-Body J-PET
geometries as a possible next generation J-PET scanner design. We present
comparative studies of performance characteristics of the cost-effective
Total-Body PET scanners using J-PET technology. We investigated in silico five
Total-Body scanner geometries. Monte Carlo simulations of the XCAT phantom, the
2-meter sensitivity line source and positronium sensitivity phantoms were
performed. We compared the sensitivity profiles for 2-gamma and 3-gamma
tomography, relative cost of the setups and performed quantitative analysis of
the reconstructed images. The analysis of the reconstructed XCAT images reveals
the superiority of the seven-ring scanners over the three-ring setups. However,
the three-ring scanners would be approximately 2-3 times cheaper. The peak
sensitivity values for two-gamma vary from 20 to 34 cps/kBq. The sensitivity
curves for the positronium tomography have a similar shape to the two-gamma
sensitivity profiles. The peak values are lower compared to the two-gamma
cases, from about 20-28 times, with a maximum of 1.66 cps/kBq. The results show
the feasibility of multi-organ imaging of all the systems to be considered for
the next generation of TB J-PET designs. The relative cost for all the scanners
is about 10-4 times lower compared to the cost of the uExplorer. These
properties coupled together with J-PET cost-effectiveness, make the J-PET
technology an attractive solution for broad application in clinics
Preliminary studies of J-PET detector spatial resolution
The J-PET detector, based on long plastic scintillator strips, was recently constructed at the Jagiellonian University. It consists of 192 modules axially arranged into three layers, read out from both sides by digital constant-threshold front-end electronics. This work presents preliminary results of measurements of the spatial resolution of the J-PET tomograph performed with ²²Na source placed at selected position inside the detector chamber