3D photon impact determination in monolithic based PET detectors using FPGA processing

Aguilar, Albert; Galasso, Matteo; Barberá, Julio; Correcher, Carlos; Fabbri, Andrea; Hernández, L.; González, Antonio J.; Benlloch, J.

doi:10.1109/rtc.2016.7543141

Cited by 4 publications

(1 citation statement)

References 6 publications

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“…There are two commonly used approaches-either attenuating the signals in such a way that it reduces the fraction of the noise in the weights that are used in the centroid algorithm, or amplifying signals and increasing the signal-to-noise ratio. The former approach is referred to as a truncated center of gravity (TCoG) (Qi et al 2007) method that is mostly used as part of a subtractive resistive readout on the hardware level (Qi et al 2007), and the latter approach includes algorithms such as raised-to-power (RTP) (Pani et al 2015, Aguilar et al 2016 or position-weighted CoG (PW-CoG) (Liu and Goertzen 2013) algorithm with various weighting functions. The usage of TCoG and RTP also comes with the advantage of making the performance of the PET detector invariant to photosensor gain variation that can happen due to fluctuations of SiPM temperature or bias voltage (Poladyan et al 2019).…”

Section: Introductionmentioning

confidence: 99%

Gaussian position-weighted center of gravity algorithm for multiplexed readout

et al. 2020

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Readout signal multiplexing is a commonly used method to reduce the electronics cost in positron emission tomography (PET) systems, and the calculation of the scintillation coordinates typically is done by using a center of gravity (CoG) technique due to its simplicity and ease of implementation. This comes with a drawback, since CoG has a non-linear response at the periphery of the detector due to the lack of weights beyond the detector. Detectors with multiplexed readout that are based on finely segmented scintillators and coarsely segmented photosensors are known to suffer from the so-called edge effect where a pile-up of the reconstructed coordinates from the edge crystals is observed. This may lead to incorrect assignment of the events to crystal pixels and result in the formation of erroneous lines of response causing a degradation of spatial resolution and reduction of image contrast. To overcome the abovementioned limitations in gamma-ray detectors with multiplexed photosensor readout, we propose to use a modified Gaussian position-weighted center of gravity (PW-CoG) technique for the calculation of gamma-ray interaction position. Here, the proposed method is applied to PET detectors with 24 24 LYSO crystals read out by 8 8 SiPM array with 64:16 row/column multiplexing. Furthermore, we compared the modified Gaussian PW-CoG and truncated center of gravity coordinate reconstruction methods. It was observed that both algorithms resolve peaks corresponding to events registered in the crystal pixels on the periphery of the crystal array. However peak-to-valley ratios and crystal resolvability metrics for the PW-CoG algorithm are generally greater.

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Section: Introductionmentioning

confidence: 99%

Gaussian position-weighted center of gravity algorithm for multiplexed readout

et al. 2020

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Algorithms to reduce the edge effect and improve the flood histogram quality of a PET detector consisting of two pixelated crystal arrays

Cong,

Kuang,

Ren

et al. 2024

Medical Physics

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PurposeThe performance of detectors is key for a PET scanner to achieve high spatial resolution and high sensitivity. This work aims to develop flood histogram generating algorithms to reduce the edge effect and improve the crystal identification of a PET detector consisting of two optically coupled pixelated scintillator detectors.MethodsThe PET detector consists of two optically coupled detectors, each consisting of a 23×23 LYSO crystal array with a crystal size of 1.0×1.0×20 mm3 read out by an 8×8 SiPM array with a pixel size of 3.0×3.0 mm2. The SiPM array is read out with a resistor network circuit to obtain four position encoding energy signals. A novel center of gravity (COG) positioning algorithm using six signals from the two detectors was proposed and compared to the traditional COG algorithms using either four or eight signals from the detectors. The raised‐to‐the‐power (RTP) method was applied to the three COG algorithms for the PET detector. Different powers of the RTP from 1.0 to 2.5 were evaluated.ResultsThe proposed COG algorithm significantly improves the crystal identification at the junction of the two detectors as compared to the COG algorithm using four signals of each detector, and improves the crystal identification at the center of the two detectors as compared to the COG algorithm using eight signals from both detectors. The RTP method significantly improves the overall flood histogram qualities of the two COG algorithms using either eight or six signals from the two detectors, and the two COG algorithm provide similar flood histogram quality when a power of 1.5 is used.ConclusionThe novel positioning algorithms reduce the edge effect and improve the flood histogram quality for a PET detector consisting of two optically coupled detectors, each consisting of a pixelated scintillator crystal array and a SiPM array with highly multiplexed four signal readout. The positioning algorithms can be used in a PET scanner to improve the spatial resolution and sensitivity.

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