Measurements and Ray-Tracing Simulations of Light Spread in LSO Crystals

Bauer, F.; Corbeil, James L.; Schmand, M.; Henseler, Debora

doi:10.1109/tns.2009.2030411

Cited by 19 publications

(19 citation statements)

References 19 publications

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“…Note that the x-axis of this figure represents total detection efficiency, and it is comprised of both light collection efficiency at the exit interface of the crystal and the PDE of the photosensor used to convert scintillation light into charge. The light collection at the exit of crystal elements with polished surfaces and lengths of 20 mm is typically reported between 40–60% [Lőrincz et al 2010, Bauer et al 2009, Auffray et al 2013, Pauwels et al 2009, Levin et al 2002]. The PDE of a photosensor tends to be between 20–30% for photomultipliers with bialkili photocathodes, and analogue SiPMs typically have an effective PDE of 30–35% when operated at a sufficient margin above the breakdown voltage, which is the case when the bias is optimized for timing measurements.…”

Section: Resultsmentioning

confidence: 99%

Analytical calculation of the lower bound on timing resolution for PET scintillation detectors comprising high-aspect-ratio crystal elements

2015

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Excellent timing resolution is required to enhance the signal-to-noise ratio (SNR) gain available from the incorporation of time-of-flight (ToF) information in image reconstruction for positron emission tomography (PET). As the detector’s timing resolution improves, so does SNR, reconstructed image quality, and accuracy. This directly impacts the challenging detection and quantification tasks in the clinic. The recognition of these benefits has spurred efforts within the molecular imaging community to determine to what extent the timing resolution of scintillation detectors can be improved and develop near-term solutions for advancing ToF-PET. Presented in this work, is a method for calculating the Cramér-Rao lower bound (CRLB) on timing resolution for scintillation detectors with long crystal elements, where the influence of the variation in optical path length of scintillation light on achievable timing resolution is non-negligible. The presented formalism incorporates an accurate, analytical probability density function (PDF) of optical transit time within the crystal to obtain a purely mathematical expression of the CRLB with high-aspect-ratio (HAR) scintillation detectors. This approach enables the statistical limit on timing resolution performance to be analytically expressed for clinically-relevant PET scintillation detectors without requiring Monte Carlo simulation-generated photon transport time distributions. The analytically calculated optical transport PDF was compared with detailed light transport simulations, and excellent agreement was found between the two. The coincidence timing resolution (CTR) between two 3×3×20 mm3 LYSO:Ce crystals coupled to analogue SiPMs was experimentally measured to be 162±1 ps FWHM, approaching the analytically calculated lower bound within 6.5%.

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Section: Resultsmentioning

confidence: 99%

Analytical calculation of the lower bound on timing resolution for PET scintillation detectors comprising high-aspect-ratio crystal elements

2015

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“…Simulation Study of the Impact of PhCs on the Performance of a State-of-the-Art PET Detector 1) Detector Setup: The simulated PET detector consists of an array of 8×8 LSO scintillator crystals of the size 4 mm × 4 mm × 20 mm and a refractive index of n LSO = 1.82 [12], [16] as depicted in Fig. 4.…”

Section: ) Transmission Simulationsmentioning

confidence: 99%

“…The LSO pixels were modeled as polished crystals with a Gaussian surface scattering coefficient of 0.02 rad. Bulk absorption and scattering are characterized by mean free paths of 600 mm and 250 mm [12]. The scintillator pixels are closely packed and separated from each other by thin air gaps.…”

Section: ) Transmission Simulationsmentioning

confidence: 99%

“…As for the pixel spacing, these parameters were chosen to match experimental results. On the bottom, the LSO array is coupled to an 8×8 array of silicon photomultipliers (SiPM) [17], [18] via a 100 µm layer of optical glue (n Glue = 1.47) [12]. The SiPMs are modeled as bulk silicon material with a refractive index of 5.06 [19], which is encapsulated with a 300 µm thick epoxy window (n Epoxy = 1.59) [20].…”

Section: ) Transmission Simulationsmentioning

confidence: 99%

“…Monte Carlo (MC) simulations are a powerful tool to study the propagation of scintillation photons in PET detectors using ray tracing algorithms based on geometric optics [1]- [3], [12]. Since these techniques are not capable of computing the diffractive effects of PhCs, an additional tool is required to solve Maxwell's equations.…”

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confidence: 99%

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Combining Photonic Crystal and Optical Monte Carlo Simulations: Implementation, Validation and Application in a Positron Emission Tomography Detector

Thalhammer

Breuer

Führer

et al. 2014

IEEE Trans. Nucl. Sci.

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Abstract-This paper presents a novel approach towards incorporating photonic crystals (PhCs) into optical Monte Carlo (MC) simulations. This approach affords modeling the full diffractive nature of PhCs including their reflection and transmission behavior as well as the manipulation of the photon trajectories through light scattering. The main purpose of this tool is to study the impact of PhCs on the light yield and timing performance of scintillator-based detectors for positron emission tomography (PET). To this end, the PhCs are translated into look-up tables and implemented into the optical MC algorithm. Our simulations are validated in optical experiments using PhC samples fabricated with electron beam lithography. The experimental results indicate that the simulations match the measurements within the accuracy of the experiments. The application of the combined simulation technique to a PET detector module predicts an increase of the total light yield by up to 23% for PhC coatings versus the reference without PhCs. Timing calculations reveal an improvement of the coincident resolving time by up to 6%. The results underline the potential of PhCs to improve light yield and timing of PET detector modules.

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Comparison of photon transport efficiency in simple scintillation electron detector configurations for scanning electron microscope

Schauer

2022

Microscopy Res & Technique

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The purpose of this paper is to find some general rules for the design of robust scintillation electron detectors for a scanning electron microscope (SEM) that possesses an efficient light-guiding (LG) system. The paper offers some general instructions on how to avoid the improper design of highly inefficient LG configurations of the detectors. Attention was paid to the relevant optical properties of the scintillator, light guide, and other components used in the LG part of the scintillation detector.

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Measurements and Ray-Tracing Simulations of Light Spread in LSO Crystals

Cited by 19 publications

References 19 publications

Analytical calculation of the lower bound on timing resolution for PET scintillation detectors comprising high-aspect-ratio crystal elements

Analytical calculation of the lower bound on timing resolution for PET scintillation detectors comprising high-aspect-ratio crystal elements

Combining Photonic Crystal and Optical Monte Carlo Simulations: Implementation, Validation and Application in a Positron Emission Tomography Detector

Comparison of photon transport efficiency in simple scintillation electron detector configurations for scanning electron microscope

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