A four-layer DOI detector with a relative offset for use in an animal PET system

Mikiko Ito, Jae Sung Lee, Sun Il Kwon, Geon Song Lee, Byungsik Hong, Kyong Sei Lee, Kwang Souk Sim, Seok Jae Lee, June Tak Rhee, Seong Jong Hong

Research output: Contribution to journalArticlepeer-review

67 Citations (Scopus)


For animal PET systems to achieve high sensitivity without adversely affecting spatial resolution, they must have the ability to measure depth-of-interaction (DOI). In this paper, we propose a novel four-layer PET system, and present the performances of modules built to verify the concept of the system. Each layer in the four-layer PET system has a relative offset of half a crystal pitch from other layers. Performances of the four-layer detector were estimated using a GATE Monte Carlo simulation code. The proposed system consists of six H9500 PMTs, each of which contains 3193 crystals. A sensitivity of 11.8% was obtained at the FOV center position of the proposed system. To verify the concept, we tested a PET module constructed using a H9500 flat panel PMT and LYSO crystals of cross-sectional area 1.5 × 1.5 mm2. The PET module was irradiated with a 1.8 MBq 22Na radiation source from the front or side of the crystals to obtain flood images of each crystal. Collimation for side irradiation was achieved using a pair of lead blocks of dimension 50 × 100 × 200 mm3. All crystals in the four layers were clearly identified in flood images, thus verifying the DOI capability of the proposed four-layer PET system. We also investigated the optimal combination of crystal lengths in the four-layer PET system using the GATE Monte Carlo simulation code to generate events from simulated radiation sources, and using the ML-EM algorithm to reconstruct simulated radiation sources. The combination of short crystal lengths near radiation sources and long crystal lengths near the PMT provides better spatial resolution than combinations of same crystal lengths in the four-layer PET system.

Original languageEnglish
Article number5485133
Pages (from-to)976-981
Number of pages6
JournalIEEE Transactions on Nuclear Science
Issue number3 PART 1
Publication statusPublished - 2010 Jun


  • Depth of interaction (DOI))
  • Four-layer animal PET
  • GATE monte carlo simulation
  • H9500 photomultiplier tube (PMT)

ASJC Scopus subject areas

  • Nuclear and High Energy Physics
  • Nuclear Energy and Engineering
  • Electrical and Electronic Engineering


Dive into the research topics of 'A four-layer DOI detector with a relative offset for use in an animal PET system'. Together they form a unique fingerprint.

Cite this