Integrated High-Resolution Multi-Channel Time-to-Digital Converters (TDCs) for PET Imaging

This contribution shows how to perform Time of Flight (TOF) measurements in Positron Emission Tomograph y (PET) s y stems using low-cost Field-Programmable Gate Arra y (FPGA) device with a resolution better than 100 ps. This is achieved with a proper management of the FPGA internal resources and with an extremel y careful device calibration process including both temperature and voltage compensation. The results of s y stem calibration and different time measurements between multiple channels are presented.

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“…The implemented TDC core relies on a Vernier delayline [6] (Fig. 2), whose scheme is presented below.…”

Section: Implementa Nonmentioning

confidence: 99%

Time of Flight measurements in PET systems using FPGAs

Torres

Aguilar

Garcia-Olcina

et al. 2012

2012 IEEE Nuclear Science Symposium and Medical Imaging Conference Record (NSS/MIC)

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“…The TDC ASIC receives the digital pulses sent by the mixed-mode readout ASIC and converts the timestamp and energy information of valid data into a digital word. The classical approach for implementing a time to digital converter is based on the use of a counter and a time interpolator, typically a delay locked loop (DLL) [13]. The former is necessary to achieve a large dynamic range while the latter increases the precision of the time measurement.…”

Section: Time To Digital Converter Asicmentioning

confidence: 99%

“…The classical approach for implementing a time to digital converter is based on the use of a counter and a time interpolator, typically a delay locked loop (DLL) [13]. The former is necessary to achieve a large dynamic range while the latter increases the precision of the time measurement.…”

Section: Time To Digital Converter Asicmentioning

confidence: 99%

An innovative detection module concept for PET

Marino¹,

Ambrosi²,

Baronti³

et al. 2012

J. Inst.

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The design of a Positron Emission Tomography detection module capable of working inside a Magnetic Resonant Imaging system is the main objective of the 4D-MPET project. Combining the two imaging technologies offers better soft tissue contrast and lower radiation doses by providing both functional and morphological information at the same time. The proposed detector will feature a three-dimensional architecture based on two tiles of Silicon Photomultipliers coupled to a single LYSO scintillator on both its faces. Silicon Photomultipliers are magneticfield compatible photo-detectors with a very small size enabling novel detector geometries that allow the measurement of the Depth of Interaction as well as a high detector packing fraction to maximize system sensitivity. Furthermore they can be fabricated using standard silicon technology, have a large gain in the order of 10 6 and are very fast thus allowing evaluating the Time of Flight. Among the other features of the proposed detection system, the architecture of the innovative readout electronics will be also described which plays a relevant role for the achievement of the desired performance and is based on custom integrated circuits. Simulation results of the whole system show good performance in terms of time and spatial resolution: a timestamp of 100 ps is the ultimate performance achievable with the use of a double threshold technique along with fast electronics. Time over threshold is exploited to provide the energy information with a bin size of 400 ps. Moreover, a z resolution of 1.4 mm Full Width at Half Maximum can be achieved. The proposed detector can also be exploited in other tracking applications, such as High Energy Physics and Astrophysics.

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“…M EASURING time-dependent digital waveforms with accuracy and precision is crucial in many fields of science and engineering, with applications ranging from wireless communication systems and GPS to medical imaging and PET scans [1], [2]. Depending on the use-case, two technologies are routinely employed: time-to-digital converters (TDCs) [3], and digital storage oscilloscopes (DSOs) [4].…”

Section: Introductionmentioning

confidence: 99%

High-Resolution Waveform Capture Device on a Cyclone-V FPGA

2021

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We introduce the waveform capture device (WCD), a flexible measurement system capable of recording complex digital signals on trillionth-of-a-second (ps) time scales. The WCD is implemented via modular code on an off-the-shelf field-programmable gate-array (FPGA, Intel/Altera Cyclone V), and incorporates both time-to-digital converter (TDC) and digital storage oscilloscope (DSO) functionality. The device captures a waveform by taking snapshots of a signal as it propagates down an ultra-fast transmission line known as a carry chain (CC). It is calibrated via a novel dynamic phase-shifting (DPS) method that requires substantially less data and resources than the state-of-the-art. Using DPS, we find the measurement resolution -or mean propagation delay from one CC element to the next -to be 4.91±0.04 ps (4.54±0.02 ps) for a pulse of logic high (low). Similarly, we find the single-shot precision -or mean error on the timing of the waveform -to be 29.52 ps (27.14 ps) for pulses of logic high (low). We verify these findings by reproducing commercial oscilloscope measurements of asynchronous ring-oscillators on FPGAs, finding the mean pulse width to be 0.240 ± 0.002 ns per inverter gate. Finally, we present a careful analysis of design constraints, introduce a novel error correction algorithm, and sketch a simple extension to the analog domain. We also provide the Verilog code instantiating our design's hardware primitives in an Appendix, and make our FPGA interfacing methods available as an open-source Python library at https://github.com/Noeloikeau/fpyga.

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Integrated High-Resolution Multi-Channel Time-to-Digital Converters (TDCs) for PET Imaging

Cited by 8 publications

References 26 publications

Time of Flight measurements in PET systems using FPGAs

Time of Flight measurements in PET systems using FPGAs

An innovative detection module concept for PET

High-Resolution Waveform Capture Device on a Cyclone-V FPGA

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