1 research outputs found
VLSI Implementation of TDC Architectures Used in PET Imaging Systems
Positron emission tomography (PET) is a medical imaging method based on the
measurement of concentrations of positron-emitting radionuclides in a living
body. In the PET imaging system, glucose is labeled with a positron-emitting
radionuclide and injected intravenously. Then, the positrons move through the
tissue and collide with the electrons of the cells in which they interact. As a
result of this interaction, two gamma rays are emitted in the opposite
direction. Gama rays emitted from cancerous tissue that has retained
radioactive glucose are detected through ring-shaped detectors. And the
detected signals are converted into an electrical response. Subsequently, these
responses are sampled with electronic circuits and recorded as histogram matrix
to generate the image set. The gamma rays may not reach the detectors located
in the opposite position in equal time. In PETs having TOF characteristics, it
is aimed to obtain better positioning information by a method based on the
principle of measuring the difference between the reach time of the two photons
to detectors. The measurement of the flight time is carried out with TDC
structures. The measurement of this time difference at the ps level is directly
related to the spatial resolution of the PET system. In this study, 45 nm CMOS
VLSI simulations of TDC structures that have various architectural approaches
were performed for use in PET systems. With the designed TDC architectures, two
gamma photons time reach to detectors have been simulated and the time
difference has been successfully digitized. In addition, various performance
metrics such as input and output voltages, time resolutions, measurement
ranges, and power analysis of TDC architectures have been determined. Proposed
Vernier oscillator-based TDC architecture has been reached 25 ps time
resolution with a low power consumption of 1.62681 mW at 1V supply voltage.Comment: 8 pages, in Turkish language. 6 figures, conference
paper,International Marmara Sciences Congess (IMASCON 2019 SPRING),
https://www.imascon.com/dosyalar/imascon2019bahar/imascon_fen_bildiriler_ciltII_bahar_2019.pdf
,
https://avesis.kocaeli.edu.tr/yayin/99073ee1-45ff-495e-9cab-42de4d0fad71/vlsi-implementation-of-tdc-architectures-used-in-pet-imaging-system