Abstract: A method and system for calibrating a PET scanner are described. The PET scanner may have a field of view (FOV) and multiple detector rings. A detector ring may have multiple detector units. A line of response (LOR) connecting a first detector unit and a second detector unit of the PET scanner may be determined. The LOR may correlate to coincidence events resulting from annihilation of positrons emitted by a radiation source. A first time of flight (TOF) of the LOR may be calculated based on the coincidence events. The position of the radiation source may be determined. A second TOF of the LOR may be calculated based on the position of the radiation source. A time offset may be calculated based on the first TOF and the second TOF. The first detector unit and the second detector unit may be calibrated based on the time offset.

Abstract: A new cultivar of Chrysanthemum, ‘Taihang's Galaxy’, characterized by it's late season blooming habit with single daisy-type fragrant inflorescences with white ray florets and gold disk florets, its hybrid vigor, its prostrate to cascading growth habit after one or two years of growth, its massive floral display, and its cold hardiness to at least U.S.D.A. 5.