An Accurate Timing Alignment Method With Time-to-Digital Converter Linearity Calibration for High-Resolution TOF PET

作者:Li Hongdi*; Wang Chao; An Shaohui; Lu Xingyu; Dong Yun; Liu Shitao; Baghaei Hossain; Zhang Yuxuan; Ramirez Rocio; Wong Wai Hoi
来源:IEEE Transactions on Nuclear Science, 2015, 62(3): 799-804.
DOI:10.1109/TNS.2015.2430751

摘要

Accurate PET system timing alignment minimizes the coincidence time window and therefore reduces random events and improves image quality. It is also critical for time-of-flight (TOF) image reconstruction. Here, we use a thin annular cylinder (shell) phantom filled with a radioactive source and located axially and centrally in a PET camera for the timing alignment of a TOF PET system. This timing alignment method involves measuring the time differences between the selected coincidence detector pairs, calibrating the differential and integral nonlinearity of the time-to-digital converter (TDC) with the same raw data and deriving the intrinsic time biases for each detector using an iterative algorithm. The raw time bias for each detector is downloaded to the front-end electronics and the residual fine time bias can be applied during the TOF list-mode reconstruction. Our results showed that a timing alignment accuracy of better than +/- 25 ps can be achieved, and a preliminary timing resolution of 473 ps (full width at half maximum) was measured in our prototype TOF PET/CT system.

  • 出版日期2015-6