A novel front-end chip for a human PET scanner based on monolithic detector blocks

Sarasola, I.; Mendes, P. Rato; Cuerdo, R.; Acilu, P. Garcia de; Navarrete, J.; M, J; Oller, J.C.; Romero, L.; Pérez, J. M.

doi:10.1088/1748-0221/6/01/c01034

Cited by 7 publications

(7 citation statements)

References 7 publications

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“…The front-end electronics of the BrainPET scanner will be based on the VATA241 ASIC, which has been characterized in [15] and is the updated version of the VATA240 ASIC used in the demonstrator presented in this work. Both ASICs have been designed and manufactured by the company Gamma MedicaIdeas Norway (GM-I) in Oslo, which has also developed other ASICs for combining nuclear medicine with MRI systems [16].…”

Section: Front-end Electronicsmentioning

confidence: 99%

“…An update of this ASIC, called VATA241, has been manufactured featuring a CFD for reducing the time-walk of the ASIC used in this prototype demonstrator down to 0.5 ns. The performance of this new ASIC has been characterized in [15], where we have obtained an intrinsic timing resolution in the order of 2 ns.…”

Section: A Front-end Electronics Performancementioning

confidence: 99%

“…We expect to significantly improve the timing resolution of our coincidence setup to a few nanoseconds using the updated ASIC VATA241 [15], which will be included in the front-end electronics for the final BrainPET scanner.…”

Section: Coincidence Operationmentioning

confidence: 99%

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PET Demonstrator for a Human Brain Scanner Based on Monolithic Detector Blocks

Sarasola

Mendes

Acilu

et al. 2011

IEEE Trans. Nucl. Sci.

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We have implemented and evaluated a positron emission tomography (PET) demonstrator using two monolithic detector blocks operating in coincidence with dedicated applicationspecific integrated circuit (ASIC) readout. Each detector is composed of a monolithic lutetium yttrium orthosilicate (LYSO) scintillator coupled to a pair of Hamamatsu S8550-02 APD arrays. The front-end electronics of this demonstrator is based on the VATA240 ASIC readout, which sums the charge provided by each row and column of the APD array. The ASIC has been characterized obtaining a noise per row or column less than 2000 electrons rms with the APD at its inputs and a good linear response in the range from 5 fC to 30 fC. We have acquired energy spectra of 22 Na and 137 Cs radioactive sources, achieving energy resolutions between 13.2% and 14.1% full width at half maximum (FWHM) at 511 keV. We have estimated the interaction position over the surface of the monolithic blocks using Neural Networks (NN) position determining algorithms, obtaining spatial resolutions at the detector level down to 2.1 mm FWHM. By using this detector technology and electronics we have achieved images of point sources with spatial resolutions as good as 2.1 mm FWHM for filtered back projection (FBP) reconstructions methods with single slice rebinning (SSRB). Based on the results obtained with this demonstrator, we are developing a PET insert for existing magnetic resonance imaging (MRI) equipment, to be installed in a collaborating hospital and used for clinical PET-MRI of the human brain.Index Terms-Application specific integrated circuit, artificial neural networks, position sensitive detectors, positron emission tomography.

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Section: Front-end Electronicsmentioning

confidence: 99%

Section: A Front-end Electronics Performancementioning

confidence: 99%

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PET Demonstrator for a Human Brain Scanner Based on Monolithic Detector Blocks

Sarasola

Mendes

Acilu

et al. 2011

IEEE Trans. Nucl. Sci.

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“…Nevertheless, we detected image distortions and compressions due to the non-linearities close to the edge of the crystals and the simplicity of that demonstrator with the absence of neighbor blocks [1]. In this work we have implemented a larger scale PET demonstrator, which is based on the new updated ASIC (VATA241) [2] and is formed by two sectors of four monolithic detector blocks placed face-to-face. This new prototype demonstrator has been built for validating the data readout architecture, the coincidence processing implemented in a Xilinx Virtex 5 field programmable gate array (FPGA), as well as the continuous neural networks (NN) training method required to determine the points of entrance over the surface of our monolithic detector blocks.…”

mentioning

confidence: 99%

Performance evaluation of a PET demonstrator for PET-MR imaging based on monolithic LYSO:Ce scintillators

Sarasola¹,

Cuerdo²,

Navarrete³

et al. 2011

J. Inst.

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We are developing a positron emission tomography (PET) insert based on avalanche photodiode (APD) arrays and monolithic LYSO:Ce scintillators for human brain functional studies to be used inside a clinical magnetic resonance imaging (MRI) equipment. In a previous work [1], we demonstrated the performance of our detectors by implementing an experimental setup consisting of two monolithic blocks working in coincidence, which were read out by the first version of an application-specific integrated circuit (ASIC), VATA240, followed by external coincidence and digitalization modules. This preliminary demonstrator showed good spatial resolution at detector level on the order of 2.2 mm full-width at half-maximum (FWHM) and good imaging qualities, which achieved reconstructed images of 22 Na point sources with spatial resolutions of 2.1 mm FWHM. Nevertheless, we detected image distortions and compressions due to the non-linearities close to the edge of the crystals and the simplicity of that demonstrator with the absence of neighbor blocks [1]. In this work we have implemented a larger scale PET demonstrator, which is based on the new updated ASIC (VATA241) [2] and is formed by two sectors of four monolithic detector blocks placed face-to-face. This new prototype demonstrator has been built for validating the data readout architecture, the coincidence processing implemented in a Xilinx Virtex 5 field programmable gate array (FPGA), as well as the continuous neural networks (NN) training method required to determine the points of entrance over the surface of our monolithic detector blocks.

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“…BrainPET II (4.5.2.2), basado en dos grupos enfrentados de 4 bloques monolíticos cada uno con lectura basada en el ASIC VATA241 [141], con ADCs discretos y procesado de coincidencias en una FPGA Virtex 5 [15] [142]. Los resultados de este demostrador se encuentran principalmente recogidos en [142] y [15].…”

Section: Demostrador Brainpet IIunclassified

Detectores monolíticos y sensores compatibles con altos campos magnéticos para tomografía por emisión de positrones

Martín¹

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This thesis is focused on the development of experimental activities used to deepen the knowledge of monolithic detector blocks as an alternative to segmented detectors for Positron Emission Tomography (PET). It includes the development, characterization, setting up, running and evaluation of PET demonstrator prototypes with monolithic detector blocks of Cerium-doped Lutetium Yttrium Orthosilicate (LYSO:Ce) using magnetically compatible sensors such as Avalanche Photodiodes (APDs) and Silicon Photomultipliers (SiPMs).The prototypes implemented with APDs were constructed to validate the viability of a high-sensitivity PET prototype that had previously been simulated, denominated BrainPET. This work describes and characterizes the integrated front-end electronics used in these prototypes, as well as the electronic readout system developed especially for them. It shows the experimental set-ups to obtain the tomographic PET images and to train neural networks algorithms used for position estimation of photons impinging on the surface of monolithic blocks.Using the BrainPET prototype, satisfactory energy resolution (13 % FWHM), spatial precision of monolithic blocks (~ 2 mm FWHM) and spatial resolution of the PET image (1.5 -1.7 mm FWHM) in the center of the Field of View (FoV) were obtained. Moreover, we proved the imaging capabilities of this demonstrator with extended sources, considering the acquisition of two simultaneous sources of 1 mm diameter placed at known distances. However, some important limitations were also detected with the BrainPET prototype. In the first place, it was confirmed that there was a lack of flexibility working with an Application Specific Integrated Circuit (ASIC) whose electronic design was not own but commercial, along with the high cost required to modify an ASIC design with such features. Furthermore, the final characterization of the BrainPET ASIC showed a timing resolution with room for improvement (~ 13 ns FWHM).Taking into consideration the limitations obtained with the BrainPET prototype, along with the technological evolution in magnetically compatible devices, the knowledge acquired with the monolithic blocks were transferred to the new technology iv available, the SiPMs. Moreover, we opted for a new strategy in the front-end electronics, the FlexToT ASIC, an own design ASIC based on a Time over Threshold (ToT) scheme. One of the most interesting features underlying a ToT architecture is the encoding of the analog input signal amplitude information into the duration of the output signals, delivering directly digital pulses. The electronic architecture helps substitute the Analog to Digital Converters (ADCs) for Time to Digital Converters (TDCs), and they are easily implemented in Field Programmable Gate Arrays (FPGA), reducing the consumption and the complexity of the design.A new prototype demonstrator based on SiPMs was implemented to validate the FlexToT ASIC for monolithic or segmented blocks. The design and characterization of the necessary front-end electronic to read-ou...

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A novel front-end chip for a human PET scanner based on monolithic detector blocks

Cited by 7 publications

References 7 publications

PET Demonstrator for a Human Brain Scanner Based on Monolithic Detector Blocks

PET Demonstrator for a Human Brain Scanner Based on Monolithic Detector Blocks

Performance evaluation of a PET demonstrator for PET-MR imaging based on monolithic LYSO:Ce scintillators

Detectores monolíticos y sensores compatibles con altos campos magnéticos para tomografía por emisión de positrones

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