Reprogrammable Acquisition Architecture for Dedicated Positron Emission Tomography

Sportelli, Giancarlo; Belcari, Nicola; Guerra, P.; Spinella, F.; Franchi, Giovanni; Attanasi, Francesca; Moehrs, Sascha; Rosso, V.; Santos, A.; Guerra, A. Del

doi:10.1109/tns.2011.2113193

Cited by 30 publications

(22 citation statements)

References 32 publications

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“…The acquisition system features a custom modular board able to handle up to 18 modules (Sportelli et al 2011a). Coincidence detection is performed by a synchronous processor operating at 240 MHz and providing a coincidence resolution of 3 ns (Sportelli et al 2011b).…”

Section: The Pet Systemmentioning

confidence: 99%

“…Based on previous experiences with the first dedicated in-beam DoPET system (Vecchio et al 2009), we developed a new in-beam PET, with wider detectors and modularized acquisition for better counting performances (Sportelli et al 2011a). In the following we present the first reconstructed PET images of the activity produced during the continuous irradiation of a polymethyl methacrylate (PMMA) phantom at the CATANA cyclotron-based proton therapy facility.…”

Section: Introductionmentioning

confidence: 99%

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First full-beam PET acquisitions in proton therapy with a modular dual-head dedicated system

et al. 2013

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During particle therapy irradiation, positron emitters with half-lives ranging from 2 to 20 min are generated from nuclear processes. The half-lives are such that it is possible either to detect the positron signal in the treatment room using an in-beam positron emission tomography (PET) system, right after the irradiation, or to quickly transfer the patient to a close PET/CT scanner. Since the activity distribution is spatially correlated with the dose, it is possible to use PET imaging as an indirect method to assure the quality of the dose delivery. In this work, we present a new dedicated PET system able to operate in-beam. The PET apparatus consists in two 10 cm × 10 cm detector heads. Each detector is composed of four scintillating matrices of 23 × 23 LYSO crystals. The Content from this work may be used under the terms of the Creative Commons Attribution 3.0 licence.

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Section: The Pet Systemmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

First full-beam PET acquisitions in proton therapy with a modular dual-head dedicated system

et al. 2013

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“…16,17 More accurate image-based approximations can be achieved using nonstationary and non-Gaussian blurring functions in the image domain. 15,33 In this work, we introduce a LM reconstruction method that is especially optimized for PET scanners composed of parallel planar detectors [34][35][36] that is able to use kernel models with an elliptical section based on MC simulations.…”

Section: Introductionmentioning

confidence: 99%

Massively parallelizable list‐mode reconstruction using a Monte Carlo‐based elliptical Gaussian model

et al. 2012

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Purpose: A fully three-dimensional (3D) massively parallelizable list-mode ordered-subsets expectation-maximization (LM-OSEM) reconstruction algorithm has been developed for highresolution PET cameras. System response probabilities are calculated online from a set of parameters derived from Monte Carlo simulations. The shape of a system response for a given line of response (LOR) has been shown to be asymmetrical around the LOR. This work has been focused on the development of efficien region-search techniques to sample the system response probabilities, which are suitable for asymmetric kernel models, including elliptical Gaussian models that allow for high accuracy and high parallelization efficien y. The novel region-search scheme using variable kernel models is applied in the proposed PET reconstruction algorithm. Methods: A novel region-search technique has been used to sample the probability density function in correspondence with a small dynamic subset of the fiel of view that constitutes the region of response (ROR). The ROR is identifie around the LOR by searching for any voxel within a dynamically calculated contour. The contour condition is currently define as a fi ed threshold over the posterior probability, and arbitrary kernel models can be applied using a numerical approach. The processing of the LORs is distributed in batches among the available computing devices, then, individual LORs are processed within different processing units. In this way, both multicore and multiple many-core processing units can be efficientl exploited. Tests have been conducted with probability models that take into account the noncolinearity, positron range, and crystal penetration effects, that produced tubes of response with varying elliptical sections whose axes were a function of the crystal's thickness and angle of incidence of the given LOR. The algorithm treats the probability model as a 3D scalar fiel define within a reference system aligned with the ideal LOR. Results:This new technique provides superior image quality in terms of signal-to-noise ratio as compared with the histogram-mode method based on precomputed system matrices available for a commercial small animal scanner. Reconstruction times can be kept low with the use of multicore, many-core architectures, including multiple graphic processing units. Conclusions: A highly parallelizable LM reconstruction method has been proposed based on Monte Carlo simulations and new parallelization techniques aimed at improving the reconstruction speed and the image signal-to-noise of a given OSEM algorithm. The method has been validated using simulated and real phantoms. A special advantage of the new method is the possibility of definin dynamically the cut-off threshold over the calculated probabilities thus allowing for a direct control on the trade-off between speed and quality during the reconstruction.

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“…On the other hand, timestamp-based coincidence detection relies on the assignment of a digital timestamp to all detected subevents independently, and a later comparison of timestamps in the digital domain in order to determine the presence of coincident pairs . 198 In its simplest implementation [330], gated coincidence detection amounts to an OR-AND or AND-OR plane of gates comparing pairs of incoming pulses followed by the generation of signals for each detector indicating the identification of a coincidence involving it. The coincidence window is then equal to twice the length T W of the timing pulses.…”

Section: Coincidence Detection Schemesmentioning

confidence: 99%

“…This is the only possible communication scheme in scanners with gated coincidence, as detector pulses need to be sent up to a common location. In timestamp-based systems, the simplest case corresponds to a single coincidence module where all timestamping nodes are directly connected [330]. This may not be possible in large scanners with a high number of timing modules, and intermediate hierarchy levels may be needed where data from lower level nodes are concentrated [343] and partial coincidence detection for their child nodes can be implemented in order to reduce their upstream bandwidth requirements.…”

mentioning

confidence: 99%

Development of a data acquisition architecture with distributed synchronization for a Positron Emission Tomography system with integrated front-end.

Varea¹,

Ramón²

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Positron Emission Tomography (PET) is a non-invasive nuclear medical imaging modality that makes it possible to observe the distribution of metabolic substances within a patient's body after marking them with radioactive isotopes and arranging an annular scanner around him in order to detect their decays. The main applications of this technique are the detection and tracing of tumors in cancer patients and metabolic studies with small animals.The Electronic Design for Nuclear Applications (EDNA) research group within the Instituto de Instrumentación para Imagen Molecular (I3M) has been involved in the study of high performance PET systems and maintains a small experimental setup with two detector modules. This thesis is framed within the necessity of developing a new data acquisition system (DAQ) for the aforementioned setup that corrects the drawbacks of the existing one. The main objective is to define a DAQ architecture that is completely scalable, modular, and guarantees the mobility and the possibility of reusing its components, so that it admits any extension of modification of the setup and it is possible to export it directly to the configurations used by other groups or experiments. At the same time, this architecture should be compatible with the best possible resolutions attainable at the present instead of imposing artificial limits on system performance. In particular, the new DAQ system should outperform the previous one.As a first step, a general study of DAQ architectures is carried out in the context of experimental setups for PET and other high energy physics applications. On one hand, the conclusion is reached that the desired specifications require early digitization of detector signals, exclusively digital communication between modules, and the absence of a centralized trigger. On the other hand, the necessity of a very precise distributed synchronization scheme between modules becomes apparent, with errors in the order of 100 ps, and operating directly over the data links. A study of the existing methods reveals their severe limitations in terms of achievable precision. A theoretical analysis of the situation is carried out with the goal of overcoming them, and a new synchronization algorithm is proposed that is able to reach the desired resolution while getting rid of the restrictions on clock iii alignment that are imposed by virtually all usual schemes. Since the measurement of clock phase difference plays a crucial role in the proposed algorithm, extensions to the existing methods are defined and analyzed that improve them significantly. The proposed scheme for synchronism is validated using commercial evaluation boards.Taking the proposed synchronization method as a starting point, a DAQ architecture for PET is defined that is composed of two types of module (acquisition and concentration) whose replication makes it possible to arrange a hierarchic system of arbitrary size, and circuit boards are designed and commissioned that implement a realization of the architecture for the...

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Reprogrammable Acquisition Architecture for Dedicated Positron Emission Tomography

Cited by 30 publications

References 32 publications

First full-beam PET acquisitions in proton therapy with a modular dual-head dedicated system

First full-beam PET acquisitions in proton therapy with a modular dual-head dedicated system

Massively parallelizable list‐mode reconstruction using a Monte Carlo‐based elliptical Gaussian model

Development of a data acquisition architecture with distributed synchronization for a Positron Emission Tomography system with integrated front-end.

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