Dual APD array readout of LSO crystals: Optimization of crystal surface treatment

Y. Shao, K. Meadors, R. W. Silverman, R. Farrell, L. Cirignano, R. Grazioso, K. S. Shah, S. R. Cherry

Research output: Contribution to journalArticlepeer-review

79 Scopus citations


We are developing a compact positron emission tomography (PET) detector module with a depth of interaction capability (DOI) based on a lutetium oxyorthosilicate (LSO) scintillator array coupled at both ends by avalanche photodiode (APD) arrays. This leads to a detector with high sensitivity that can provide high and uniform image resolution. We report studies on improving the DOI resolution by optimizing the crystal surface treatment. Six 2 × 2 × 20 mm LSO crystals were treated with different surface finishes along their length: raw saw-cut, polished optical finish, and chemically etched by hot anhydrous phosphoric acid (H3PO4) with etching times varying from 1 to 5 min. The ratio of the signals from the two APD arrays was used to measure DOI, and the sum of the signals to measure the total light output. Crystals finished by chemical etching for 2-3 min gave the best overall detector performance, with DOI resolutions ranging from 3.1 to 3.9 mm for events above a 150-keV threshold and uniform light output for different DOI positions. The energy resolution ranged between 14% and 18%. This detector design appears promising for PET applications requiring very high resolution and high sensitivity, for example, in small animal imaging and human breast imaging.

Original languageEnglish (US)
Pages (from-to)649-654
Number of pages6
JournalIEEE Transactions on Nuclear Science
Volume49 I
Issue number3
StatePublished - Jun 2002


  • Avalanche photodiodes
  • Depth of interaction
  • Positron emission tomography (PET)
  • Scintillation detector

ASJC Scopus subject areas

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


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