We present the first experimental
evaluation of a depth-of-interaction (DOI) positron emission tomography (PET)
detector using a digital silicon photomultiplier (dSiPM). To measure DOI
information from a mono-layer array of scintillation crystals with a single-ended
readout, our group has previously proposed and developed a new method based on
light spread using triangular reflectors. Since this method relies on
measurement of the light distribution, dSiPM, which has a fully digital
interface, has several merits for our DOI measurement. The DOI PET detector
comprised of a dSiPM sensor (DPC-3200-22-44) coupled with a 14 × 14 array
of 2 mm × 2 mm × 20 mm unpolished LGSO crystals. All crystals were covered
with triangular reflectors. To obtain a good performance of the DOI PET
detector, several parameters of detector were selected as a preliminary
experiment. Detector performance was evaluated with the selected parameters and
the optimal experimental setup, and a DOI measurement was conducted by irradiating
the crystal block at five DOI positions spaced at intervals of 4 mm.
Maximum-likelihood estimation was employed for DOI positioning and the optimal
DOI estimation scheme was also investigated in this study. As a result, the DOI
PET detector showed clear crystal identification. The energy resolution
(full-width at half-maximum (FWHM)) averaged over all depths was
10.21% ± 0.15% at 511 keV, and time resolution averaged over all depths was
1198.61 ± 39.70 ps FWHM. The average DOI positioning accuracy for all
depths was 74.22% ± 6.77%, which equates to DOI resolution of 4.67 mm. Energy
and DOI resolutions were uniform over all crystal positions except for the back
parts of the array. Furthermore, additional simulation studies were conducted
to verify the results of our DOI measurement method that is combined with dSiPM
technology. In conclusion, our continuous DOI PET detector coupled with dSiPM
is a promising PET/MRI detector with DOI-encoding capability.
single crystal.
Source:IOPscience
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