@misc{oai:repo.qst.go.jp:00078111,
 author = {Kang, Hangyu and Nishikido, Fumihiko and Yoshida, Eiji and Sakai, Toshiaki and Yamaya, Taiga and Kang, Hangyu and Nishikido, Fumihiko and Yoshida, Eiji and Yamaya, Taiga},
 month = {Apr},
 note = {[Purpose]
Small animal positron emission tomography (PET) has been playing an important role in preclinical
research. However, a conventional PET scanner has a large gap between the detector blocks due to the box
shape crystal geometry which resulted in a sensitivity loss. The aim of this study is to develop a trapezoid
crystal based small animal PET detector using subsurface laser engraving (SSLE) technique for high
sensitivity and high resolution PET scanner research.
[Methods]
The proposed trapezoidal geometry small animal DOI PET detector consists of a three trapezoid LYSO
plates, and multi-pixel photon counters (MPPCs). The 0.9 mm thick LYSO plates were pixelized by SSLE
in X-direction with pixel pitches of 1.02 mm and 1.707 mm at the top and bottom surfaces, respectively.
The LYSO in DOI direction was remained as continuous without SSLE processing. The SSLE processed
LYSO plates were optically isolated each other by ESR reflector direction. The scintillation light from the
top and bottom surfaces of trapezoid LYSO crystal was readout by a 7×6 array MPPC (Pitch=2.4 mm), and
an 8×4 array MPPC (Pitch=3.2 mm), respectively. In order to evaluate the DOI resolution, a collimated 511
keV photon was irradiated to the LYSO crystal (lead slit width=1.2 mm) for different DOI positions (2, 6,
10, 14, and, 18 mm). The DOI resolution was calculated by using the signal amplitude ratio of the two
MPPCs.
[Results]
All the 15×3 LYSO crystals could be resolved clearly. The energy resolution and DOI resolution were
measured to be less than 25% and 3.5 mm, respectively. The DOI ratio showed non-linear characteristics
due to the trapezoid crystal geometry.
[Conclusion]
In conclusion, we demonstrated the feasibility of a trapezoid geometry small animal DOI PET detector
using SSLE technique. In the future, a prototype trapezoid geometry small animal PET scanner will be
developed., 第117回日本医学物理学会学術大会},
 title = {Initial results of trapezoid geometry small animal DOI PET detector using SSLE},
 year = {2019}
}