Experimental studies of the DOI decoding accuracy of PET detectors with light sharing window

Positron emission tomography system without depth of interaction decoding capability has parallax error problem deteriorating the image quality in peripheral FOV. Light-sharing-window, which means replacing the reflection between segmented crystals by optical glue physically, can guide the photons to the surrounding crystal and encode the DOI information. The purposes of this study is to investigate LSW and the decoding method for DOI measurement by experiment. In this work, we developed a detector with LSW. By analyzing the flood map and conducting parallel exposure experiment, we defined the relationship between map pixel and continuous DOI information. (1) 6 mm SiPMs has better decoding performance than 3 mm SiPMs. (2) The best MAE resolution is 0.8 mm in central area and the average resolution is 1.182 mm. (3) We can optimize window height and SiPM coupling method to achieve higher DOI resolution. (4) The average MAE resolution improves when the segmented crystal numbers increase. Light sharing window method is a very promising method for accurate DOI measurements. Our next step is to conduct simulation to find out appropriate window settings with LSW. Experiments of different window height samples and coupling methods would be carried out.