RT Journal Article
SR Electronic
T1 First prototype of a novel dual round-edge detector arrangement for breast PET imaging
JF Journal of Nuclear Medicine
JO J Nucl Med
FD Society of Nuclear Medicine
SP 1707
OP 1707
VO 62
IS supplement 1
A1 Go Akamatsu
A1 Eiji Yoshida
A1 Hideaki Tashima
A1 Shigeki Ito
A1 Miwako Takahashi
A1 Taiga Yamaya
YR 2021
UL http://jnm.snmjournals.org/content/62/supplement_1/1707.abstract
AB 1707Objectives: 18F-FDG PET is useful for diagnosis of breast cancer. Compared to whole-body imaging, local breast imaging with a dedicated PET system can more clearly visualize the extent of the primary breast tumor and axillary lymph nodes metastasis. Breast-dedicated PET systems are categorized into two geometries: a ring-shaped detector arrangement and a dual flat-panel detector arrangement. Although the flat-panel system allows imaging axillary lymph nodes from a similar view as X-ray mammography, PET images are blurred (i.e. spatial resolution is degraded) in the direction perpendicular to the detectors due to the limited angular coverage. To compensate for this issue, we proposed a dual round-edge detector arrangement, in which the detector blocks at both edge positions were tilted toward the center of the field-of-view (FOV). The proposed detector arrangement is expected to reduce image blurring and improve spatial resolution while keeping the advantages of the dual panel arrangement. For a proof of concept, we developed a small prototype and evaluated the spatial resolution. Methods: We used the crosshair light-sharing (CLS) detectors which had depth-of-interaction (DOI) and time-of-flight (TOF) measurement capabilities*. A 14×14 array of 1.45×1.45×15 mm3 GFAG scintillator was coupled with an 8×8 array of silicon photomultipliers (SiPMs) each with a photosensitive area of 3.0×3.0 mm2. DOI was digitalized into three bins. The data acquisition system was the TOFPET2 ASIC (PETsys Electronics), which was designed to digitize energy and time signals from photo sensors. The small prototype was composed of 32 detector blocks. We examined the conventional flat-panel arrangement and our proposed round-edge arrangement. A 22Na Derenzo-like multi-rod phantom (rod diameters: 1.6, 2.2, 3.0, 4.0, 5.0 and 6.0 mm) was used for spatial resolution measurement. The phantom was measured (90 min) in the two directions (coronal and axial planes) at the center of the FOV. Results: In the coronal plane, the 1.6 mm rods were clearly resolved in both arrangements. In the axial plane, the round-edge arrangement significantly improved the spatial resolution compared with the flat-panel arrangement. While the conventional flat-panel arrangement could not resolve the 3.0 mm rods, the proposed round-edge arrangement resolved the 2.2 mm rods. Conclusion: The proposed dual round-edge detector arrangement showed better spatial resolution than the conventional flat-panel arrangement while keeping the geometrical advantage for the breast PET imaging. (*Yoshida, et al. A crosshair light sharing PET detector with DOI and TOF capabilities using four-to-one coupling and single-ended readout. IEEE TRPMS 2020.)