LAUSR

To measure the depth of interaction, we used two layers of scintillation pixels and a silicon photomultiplier (SiPM) to design a detector, and a DETECT2000 simulation was conducted to evaluate its performance. All surfaces of the scintillation pixels of the bottom layer were treated with a reflector except for the part that was optically connected to the SiPM or the scintillation pixels of the top layer. In addition, a reflector was partially applied to the scintillation pixels of the top layer. This design allows light to travel to other scintillation pixels through the area where no reflectors are applied so that the images of the scintillation pixels are formed at different points for each layer in the planar image. A gamma-ray reaction was generated at the center of each layer to obtain planar images, and the depth of interaction was measured. In addition, by measuring the intervals between the peaks at the point where the image of scintillation pixels was formed, we evaluated the depth of interaction according to the length of the area to which the reflector had not been applied. Due to the area of the scintillation pixel of the top layer that was not treated with the reflector, the depth of interaction could be measured in three layers. When this detector module is used for preclinical positron emission tomography (PET), the spatial resolution on the edges of the detection field of view can be improved by measuring the depth of interaction.