Feasibility study of an axially extendable multiplex cylinder PET

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A conventional PET scanner has a 15-25 cm axial field-of-view (FOV) and images the whole body using about six bed positions. We proposed our original OpenPET geometry which can extend the axial FOV with a limited number of detectors. For an alternative approach, we then designed an axially extendable multiplex cylinder (AEMC) PET scanner to provide high versatility for clinical and research studies using a silicon-photomultiplier (Si-PM)-based DO! detector. Since SiPMs have high gain like PMTs and a compact design, the SiPM-based detector is expected to enable various new detector arrangements. The AEMC-PET scanner consists of four independent and laminated detector rings using a four-layer depth-of-interaction (DO!) detector. This PET scanner can extend the axial FOV as each stacked detector ring can be slid aside. When this scanner is used for the four-layer DO! detector, its minimum axial FOV is 24 cm and its maximum crystal thickness is 3 cm. On the other hand, the axial FOV can be extended to 96 cm while keeping a continuous axial FOV, but the crystal thickness must be 114 of 3 cm. In addition, using the OpenPET geometry, the axial FOV can be extended to 168 cm. In this work, we studied the feasibility of the PET scanner with a variable axial FOV using Monte Carlo simulation. For the 180cm line source simulation, the 96-cm axial FOV was obtained with twofold better sensitivity compared to the 24-cm axial FOV. Also, we showed that the AEMC-PET scanner had a continuous axial FOV to 168 cm. We expect the AEMC-PET scanner will provide high versatility such as for measuring trace whole-body uptakes while keeping the continuous axial FOV and the scan time for static images will be reduced with a limited number of detectors.