A Time-Walk and Timing-Shift Correction Method for Dual-Ended Readout TOF-DOI PET Detectors

Positron emission tomography (PET) detectors suffer from time-walk when the leading edge discriminator is employed for timing pick-off as well as a timing-shift when thick crystals are utilized due to the depth-of-interaction (DOI) effect. In this study, a combined time-walk and timing-shift correction method was proposed for dual-ended readout PET detectors. To evaluate the proposed method, a pair of dual-ended readout PET detectors was constructed. Each detector was based on two Hamamatsu S14161-3050-08 silicon photomultiplier (SiPM) arrays coupled to both ends of an <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mn>8</mml:mn> <mml:mo>×</mml:mo> <mml:mn>8</mml:mn></mml:math> arrays of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mn>3</mml:mn> <mml:mo>.</mml:mo> <mml:mn>1</mml:mn> <mml:mo>×</mml:mo> <mml:mn>3</mml:mn> <mml:mo>.</mml:mo> <mml:mn>1</mml:mn> <mml:mo>×</mml:mo> <mml:mn>20</mml:mn> <mml:msup><mml:mrow><mml:mspace></mml:mspace> <mml:mi>m</mml:mi> <mml:mi>m</mml:mi></mml:mrow> <mml:mrow><mml:mn>3</mml:mn></mml:mrow> </mml:msup> </mml:math> LYSO crystals with a 3.2 mm pitch. By employing the relationship between the energies and detected time differences of events, the time-walk and timing-shift were effectively corrected. The coincidence time resolution of the two detectors improved from <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mn>260</mml:mn> <mml:mo>.</mml:mo> <mml:mn>7</mml:mn> <mml:mo>±</mml:mo> <mml:mn>1</mml:mn> <mml:mo>.</mml:mo> <mml:mn>0</mml:mn> <mml:mspace></mml:mspace> <mml:mtext>ps</mml:mtext></mml:math> to <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mn>229</mml:mn> <mml:mo>.</mml:mo> <mml:mn>4</mml:mn> <mml:mo>±</mml:mo> <mml:mn>1</mml:mn> <mml:mo>.</mml:mo> <mml:mn>0</mml:mn> <mml:mspace></mml:mspace> <mml:mtext>ps</mml:mtext></mml:math> when a 400-650 keV energy window was used to select events. These results demonstrate the effectiveness of the proposed time-walk and timing-shift correction method.