Dual-wavelength laser polarimeter and its performance capabilities

Shopa, Yaroslav; Shopa, Mykola; Ftomyn, Nazar

doi:10.1016/j.opelre.2017.01.001

Cited by 9 publications

(11 citation statements)

References 20 publications

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“…Post-simulation smearing of hit positions and times of hits was performed to represent signal readouts with CRT in the 50 − 500-ps range. The highest value is close to the results from the early experiments with 3-layer "big barrel" J-PET prototype [55,58,69], the lowest -reflects a theoretical minimum for BC-420 scintillators with WLS attached, previsioned for the future development of J-PET [47]. We shall refer to the latter as "Ideal + WLS".…”

Section: Simulation Setup 221 Scanner Geometriessupporting

confidence: 75%

“…1 is related to the i-th emitted pair of back-to-back γ-photons. p i (s, φ, ζ, θ) then becomes a delta-like function (unnormalised unit impulse), and filtering over s will return the filter itself: p i (s) * w(s) = w(s), where w(s) = F −1 W (ω s ) [69]. The eventually reconstructed image fN LOR (x ) is a sum over the N LOR back-projections each comprising a single LOR:…”

Section: Event-based Time-of-flight Fbp In the Image Domainmentioning

confidence: 99%

“…1) mostly affect the axial direction. We shall utilise two different approaches for their definition: a) Low-pass filtering, introduced in our work [69], aimed at suppressing noise by using Gaussian cumulative distribution function (CDF)cdf(x, µ, σ). Kernel components can then be expressed as follows:…”

Section: Event-based Time-of-flight Fbp In the Image Domainmentioning

confidence: 99%

“…A modification of the multivariate KDE, applied to MLP (KDE MLP), using an asymmetric 3D kernel that includes a 2D filtered back-projection (FBP) component, has been introduced in recent works related to the total-body J-PET [69,45]. It integrates separate 3D reconstructions of each emission event and can be launched in parallel.…”

Section: Introductionmentioning

confidence: 99%

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Optimisation of the event-based TOF filtered back-projection for online imaging in total-body J-PET

Shopa,

Klimaszewski,

Kopka

et al. 2021

Preprint

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We perform a parametric study of the newly developed time-of-flight (TOF) image reconstruction algorithm, proposed for the real-time imaging in total-body Jagiellonian PET (J-PET) scanners. The asymmetric 3D filtering kernel is applied at each most likely position of electron-positron annihilation, estimated from the emissions of back-to-back γ-photons. The optimisation of its parameters is studied using Monte Carlo simulations of a 1-mm spherical source, NEMA IEC and XCAT phantoms inside the ideal J-PET scanner. The combination of high-pass filters which included the TOF filtered back-projection (FBP), resulted in spatial resolution, 1.5 times higher in the axial direction than for the conventional 3D FBP. For realistic 10-minute scans of NEMA IEC and XCAT, which require a trade-off between the noise and spatial resolution, the need for Gaussian TOF kernel components, coupled with median post-filtering, is demonstrated. The best sets of 3D filter parameters were obtained by the Nelder-Mead minimisation of the mean squared error between the resulting and reference images. The approach allows training the reconstruction algorithm for custom scans, using the IEC phantom, when the temporal resolution is below 50 ps. The image quality parameters, estimated for the best outcomes, were systematically better than for the non-TOF FBP.

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Section: Simulation Setup 221 Scanner Geometriessupporting

confidence: 75%

Section: Event-based Time-of-flight Fbp In the Image Domainmentioning

confidence: 99%

Section: Event-based Time-of-flight Fbp In the Image Domainmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Optimisation of the event-based TOF filtered back-projection for online imaging in total-body J-PET

Shopa,

Klimaszewski,

Kopka

et al. 2021

Preprint

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“…Three characteristic polarizer azimuths are easily found experimentally for a paraboloid in the form given by (1). The expressions for these azimuths are as follows (Shopa et al, 2017b):…”

Section: Conventional Haup Experimentsmentioning

confidence: 99%

Polarimetric studies of L-arginine-doped potassium dihydrogen phosphate single crystals

Shopa

Shribak

et al. 2020

J Appl Cryst

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Conoscopic interference patterns, channelled spectra and polarimetric techniques have been used for the characterization of pure and doped (with L-arginine amino acid) potassium dihydrogen phosphate (KDP) single crystals. Experimental polarimetric data have been obtained for the frequently used wavelength of 633 nm and for two close wavelengths of 532 and 543 nm in a high-accuracy dual-wavelength polarimeter. The measurement of eigenwave ellipticity in the [100] and [010] directions and between 295 and 340 K shows small differences in the absolute values of the specific optical rotations of KDP crystals doped with L-arginine in the range of 0.7–3.8 wt%. It is found that the gyration tensor component g 11, specific optical rotation and eigenwave ellipticity show different dispersion in the visible spectral region.

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Optical activity and electro-optic effect of l-arginine doped KDP single crystals

Shopa

Kostenyukova

et al. 2019

Optics & Laser Technology

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Dual-wavelength laser polarimeter and its performance capabilities

Cited by 9 publications

References 20 publications

Optimisation of the event-based TOF filtered back-projection for online imaging in total-body J-PET

Optimisation of the event-based TOF filtered back-projection for online imaging in total-body J-PET

Polarimetric studies of L-arginine-doped potassium dihydrogen phosphate single crystals

Optical activity and electro-optic effect of l-arginine doped KDP single crystals

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