A Lower-Cost High-Resolution LYSO Detector Development for Positron Emission Mammography (PEM)

Ramirez, Rocio; Zhang, Yuxuan; Liu, Shitao; Li, Hongdi; Baghaei, H.; An, Shaohui; Wang, Chao; Jan, Meei-Ling; Wong, Wai-Hoi

doi:10.1109/tns.2009.2030193

Cited by 14 publications

(2 citation statements)

References 21 publications

(10 reference statements)

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“…Pixel decoding factors. One way of determining the resolution with which we can resolve one pixel from the neighbour ones is to measure the peak to valley ratio P2V in the flood map [66].…”

Section: Spatial Calibrationmentioning

confidence: 99%

Comparison of LSO and BGO block detectors for prompt gamma imaging in ion beam therapy

Hueso-González¹,

Biegun²,

Dendooven³

et al. 2015

J. Inst.

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A major weakness of ion beam therapy is the lack of tools for verifying the particle range in clinical routine. The application of the Compton camera concept for the imaging of prompt gamma rays, a by-product of the irradiation correlated to the dose distribution, is a promising approach for range assessment and even three-dimensional in vivo dosimetry.Multiple position sensitive gamma ray detectors arranged in scatter and absorber planes, together with an imaging algorithm, are required to reconstruct the prompt gamma emission density map. Conventional block detectors deployed in Positron Emission Tomography (PET), which are based on Lu 2 SiO 5 :Ce (LSO) and Bi 4 Ge 3 O 12 (BGO) scintillators, are suitable candidates for the absorber of a Compton camera due to their high density and absorption efficiency with respect to the prompt gamma energy range (several MeV).We compare experimentally LSO and BGO block detectors in clinical-like radiation fields in terms of energy, spatial and time resolution. The high energy range compensates for the low light yield of the BGO material and boosts significantly its performance compared to the PET scenario. Notwithstanding the overall superiority of LSO, BGO catches up in the field of prompt gamma imaging and can be considered as a competitive alternative to LSO for the absorber plane due to its lower price and the lack of intrinsic radioactivity.

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“…Pixel decoding factors. One way of determining the resolution with which we can resolve one pixel from the neighbour ones is to measure the peak to valley ratio P2V in the flood map [66].…”

Section: Spatial Calibrationmentioning

confidence: 99%

Comparison of LSO and BGO block detectors for prompt gamma imaging in ion beam therapy

Hueso-González¹,

Biegun²,

Dendooven³

et al. 2015

J. Inst.

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“…The PMT-Quadrant-Sharing (PQS) detector design has some features that could provide good timing resolution. These features include the lack of an external light guide, which could maximize the light collection efficiency and increase the pulse-height uniformity of the detector blocks [14]- [16]. Higher photoelectron collection efficiency and shorter light transmission paths lead to better timing resolution.…”

Section: Introductionmentioning

confidence: 99%

Timing Performance Evaluation of PMT-Quadrant-Sharing LYSO Detectors for Time-of-Flight PET

Liu

et al. 2011

IEEE Trans. Nucl. Sci.

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Time-of-flight (TOF) data can improve the imaging quality of positron emission tomography (PET) cameras by estimating the location of the positron annihilation. In this study, we measured the TOF resolution of lutetium yttrium orthosilicate (LYSO) blocks based on the photomultiplier-quadrant-sharing (PQS) design, which has no external light guide and therefore has higher light collection efficiency than the conventional block design with a light guide. We investigated three digital timing methods to achieve better timing resolution: constant fraction discriminationleading edge discrimination, and linear fitting. A time-energy correction, estimated from a least mean square fit, was applied to minimize time walk caused by the variation of signal shapes. The average block-to-block coincidence timing resolution for two 13 13 blocks, each made of 4 4 20 mm 3 LYSO crystals, with fast R9779 PMTs from Hamamatsu (51-mm diameter) was estimated to be 422 ps (full width at half maximum). Another 13 13 block of smaller 1.4 1.4 10 mm 3 LYSO crystals coupled to regular 19-mm-diameter XP1912 PMTs from Photonis was also tested and an average block-to-block timing resolution of 527 ps was achieved. This study shows that with PQS detector blocks, good time resolution suitable for TOF PET systems can be obtained, as well as high spatial resolution and lower PMT costs.

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Energy spectra due to the intrinsic radiation of LYSO/LSO scintillators for a wide range of crystal sizes

Domínguez-Jiménez

Alva‐Sánchez

2021

Medical Physics

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Most detectors in current positron emission tomography (PET) scanners and prototypes use lutetium oxyorthosilicate (LSO) or lutetium yttrium oxyorthosilicate (LYSO) scintillators. The aim of this work is to provide a complete set of background energy spectra, due to the scintillator intrinsic radioactivity, for a wide range of crystal sizes. Methods: An analytical model, developed and validated in a previous work, was used to obtain the background energy spectra of square base cuboids of different dimensions. The model uses the photon absorption probabilities of the three gamma rays (88, 202, and 307 keV) emitted following the beta decay of 176 Lu to 176 Hf excited states. These probabilities were obtained for each crystal size considered in this work from Monte Carlo simulations using the PENELOPE code. The probabilities are then used to normalize and shift the beta spectrum to the corresponding energy value of the simultaneous detection of one, two, or three gamma rays in the scintillator. The simulated cuboids had side lengths of 5, 10, 20, 30, 40, 50, and 60 mm and crystal thickness T = 2.5, 5, 10, 15, and 20 mm. From these results a complete set of energy spectra, including intermediate dimensions, were obtained. In addition, LYSO and LSO were compared in terms of their analytical background energy spectra for two crystal sizes. The analytical spectra were convolved using a variable Gaussian kernel to account for the energy resolution of a typical detector. A parameterization of the photon absorption probabilities for each gamma ray energy as a function of the cuboid volume to surface area ratio was obtained. Results: A data set of L(Y)SO background energy spectra was obtained and is available for the reader as 2D histograms. The model accurately predicts the structure of the energy spectra including the relative peak and valley intensities. The data allow visualizing how the structure evolves with increasing crystal length and thickness. Lutetium yttrium oxyorthosilicate and LSO present very similar background energy spectra for the range of sizes studied in this work and therefore the data generated can be confidently used for both scintillator materials. The filtered spectra showed a variable shift in the main peaks, depending on crystal size, alerting that to achieve a correct detector calibration using the background spectrum is not straight forward and requires precise data analysis and measurements. In addition, we found that square base L(Y)SO cuboids with same volume to surface area ratio have background spectra with the same structure. Conclusions: We present the energy spectra of L(Y)SO crystal of different sizes which will be very useful for industry and research groups developing and simulating detectors for positron imaging applications in terms of calibration, quality assurance, crystal maps, detector fine gain tuning, background reduction and other applications using the long-lived 176 Lu source. We analyzed the data produced in this work and found that crystal cuboids with equal volume to su...

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A Lower-Cost High-Resolution LYSO Detector Development for Positron Emission Mammography (PEM)

Cited by 14 publications

References 21 publications

Comparison of LSO and BGO block detectors for prompt gamma imaging in ion beam therapy

Comparison of LSO and BGO block detectors for prompt gamma imaging in ion beam therapy

Timing Performance Evaluation of PMT-Quadrant-Sharing LYSO Detectors for Time-of-Flight PET

Energy spectra due to the intrinsic radiation of LYSO/LSO scintillators for a wide range of crystal sizes

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