[19a-D61-1~11] 2.1 Detection Devices

11:15 AM - 11:30 AM JST(2:15 AM - 2:30 AM UTC)Presentation by Applicant for JSAP Young Scientists Presentation AwardEnglish Presentation

[19a-D61-9] DOI identification in HR-GAGG and GAGG phoswich detector using a new PSD method using dTOT and TOT.

〇(PC)Donghwan Kim¹, Moh Hamdan¹, Kenji Shimazoe¹, Hiroyuki Takahashi¹ (1.The Univ. of Tokyo)

Keywords:

Scintillation detector,Pulse shape discrimination,Depth of interaction

Introduction
Depth of interaction (DOI) identification is important in reducing parallax error in positron emission tomography (PET). A special reflector pattern in the crystal block, a dual-sided readout of crystals, pulse height and time over threshold (TOT) comparison, etc., have been proposed in the past. The dual-sided readout can be applied to a parallel and independent readout system. However, special treatment on the surface of the crystals is required, and two SiPM arrays are needed for one detector block. Other methods are used for charge-sharing design. In this study, a new method for DOI identification suitable for individual readout is proposed with dynamic time over threshold (dTOT) and time over threshold (TOT) in a phoswich detector composed of HR-GAGG and GAGG.
Methods and Results
dTOT represents the pulse height, and TOT relative to dTOT indicates the decay constant. An interaction in HR-GAGG shows longer TOT relative to dTOT because HR-GAGG has a longer decay time. By measuring the TOT relative to dTOT, the interaction crystal can be estimated. The figure of merit (FOM) of the proposed PSD for DOI identification at 511 keV was 1.4.
Conclusion
The proposed method could identify interaction crystals. It requires an additional wire and a comparator for TOT to a typical dTOT circuit for application to a parallel readout system. The presentation will discuss more details including the verification of the method.