@misc{oai:repo.qst.go.jp:00067823,
 author = {Yoshida, Eiji and et.al and 吉田 英治},
 month = {Jun},
 note = {Objectives: A high sensitivity and high resolution positron emission tomograph (PET) is expected for investigating drug effects and metabolism in humans. A depth of interaction (DOI) detector developed for such a purpose is to be used for the brain PET scanners, jPET-D4, at NIRS, and it should be improved energy resolution for high performance PET image. We present a new energy correction procedure for the fluctuation among the crystal elements in the DOI detector.
Methods: The DOI detector consists of 8x8 crystal blocks with 4 layers of 2x2 GSO arrays coupled to a 52 mm square 256ch PS-PMT. The size of crystal element is 2.9x2.9x7.5 mm3. The crystals in layers 1 and 2 are 0.5 mol% and the crystals in layer 3 and 4 are 1.5 mol% in doped Ce. We call most nearest layer to the PS-PMT first layer. Detected events are projected on a 2D positioning map (2DMAP) by Anger calculation. DOI information is extracted pulse shape discrimination and position of 2DMAP. Detected events estimate crystal number by referred position of 2DMAP with statistical model based on the Gaussian distribution. This method can control crystal boundaries to negotiate for high sensitivity or high resolution by variance of Gaussian distribution. We estimate light output of each crystal element by result of crystal identification, and generate a Look-Up-Table (LUT) for energy correction. Energy LUT can normalize energy spectrum from each crystal element.
Results: 2DMAP successfully identifies crystal elements. In this case, we choose a mode of the highest sensitivity. Deviation of light output of each crystal element is 28%. Energy resolution before energy correction is 74%. Energy resolution after energy correction ignored DOI information is 34%. Using DOI information, energy resolution of 20% has been achieved after energy correction. Energy resolutions of each DOI layer are 34% for first layer, 25% for second layer, 19% for third layer, 18% for fourth layer. Energy resolution of lower layer increases, because some events of lower layer are caused by inter detector scatter with upper layer. 
Conclusions: In this work, we introduced a new method of crystal identification and energy correction. Preliminary results indicated that the DOI detector improves energy resolution by corrected light output of each crystal element., 第51回米国核医学会},
 title = {ENERGY CORRECTION PROCEDURE OF DOI DETECTOR CONSTRUCTED FROM 1024 GSO CRYSTALS FOR PET SCANNER},
 year = {2004}
}