Abstract:
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In this work the implementation of a Time-to-Digital Converter (TDC) using a Nutt
delay line FPGA-based and applied on a Positron Emission Tomography (PET) device is going
to be presented in order to check the system’s ...[+]
In this work the implementation of a Time-to-Digital Converter (TDC) using a Nutt
delay line FPGA-based and applied on a Positron Emission Tomography (PET) device is going
to be presented in order to check the system’s suitability for Time of Flight (TOF) measurements.
In recent years, FPGAs have shown great advantages for precise time measurements in PET. The
architecture employed for these measurements is described in detail. The system developed was
tested on a dedicated breast PET prototype, composed of LYSO crystals and Positive Sensitive
Photomultipliers (PSPMTs). Two distinct experiments were carried out for this purpose. In the
first test, system linearity was evaluated in order to calibrate the time measurements, providing a
linearity error of less than 2% and an average time resolution of 1.4 ns FWHM. The second set
of measurements tested system resolution, resulting in a FWHM as good as 1.35 ns. The results
suggest that the coincidence window for the current PET can be reduced in order to minimize the
random events and thus, achieve better image quality
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