Small animal PET detector design with new 3D positioning method using quasi-block scintillator and MLPE

초록

To improve both spatial resolution and sensitivity, a depth of interaction (DOI) detector module using a quasi-block scintillator was designed. For gamma-ray events generated within the quasi-block scintillator, a look-up table (LUT) was created through the distribution of signals from the photosensor for each position. The optimal position was tracked using maximum likelihood position estimation (MLPE). In the previous study, 16 channels were used to create the LUT, compared to the 4 channels used in this study. DETECT2000 simulation was performed to evaluate the performance of the proposed detector and to compare and analyze it with the previously designed detector. Eight quasi-block scintillators measuring 18 mm (X) x 2 mm (Y) x 10 mm (Z) were arranged in the Y-axis direction to construct a scintillator block. A detector was subsequently constructed using an 8 x 8-channel photosensor with an anode measuring 2 mm x 2 mm to create a LUT where the signal of 64 channels was reduced to 4 channels. The intrinsic spatial resolution of the detector and the positioning accuracy in the depth direction were evaluated by measuring the positions of gamma-ray events generated at 0.1 mm intervals in the X-axis and Z-axis directions. Results showed the intrinsic spatial resolution measured by the LUT obtained through sampling of 2 mm averaged 2.36 mm, and the error rate for DOI measurement was about 9%. These results are similar to what was obtained in previous studies, meaning that sufficient intrinsic spatial resolution and DOI measurement accuracy can be exhibited when only 4 channels are used. If the detector designed in this study is used, a system with excellent sensitivity and very good spatial resolution can be designed even with a small number of output channels.

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