一种基于晶体间光分享原理的深度测量PET探测器 Development of a depth-encoding PET detector module based on light sharing between adjacent crystals 邝忠华，杨茜，王晓辉，付鑫，任宁，张春晖，赵斌清，桑子儒，杨永峰* 中国科学院深圳先进技术研究院 保罗C. 劳特伯生物医学成像研究中心

Detector Design and Measurements Outline Introduction Detector Design and Measurements Results Conclusions

I. Introduction DOI effect in whole body and total body PET scanner Whole PET scanner Total Body PET scanner 20 cm None-DOI detector 200 cm DOI detector

Timing resolution: 500 ps  7.5 cm I. Introduction Time of flight (TOF) PET DOI TOF-PET ∆𝒙=𝒄× ∆𝒕 𝟐 Timing resolution: 500 ps  7.5 cm We aim to develop a depth-encoding PET detector with good timing resolution.

II. Detector Design and Measurements 𝐷𝑂𝐼 𝑅𝑎𝑡𝑖𝑜= 𝐸 𝑆𝑖𝑃𝑀1 𝐸 𝑆𝑖𝑃𝑀1 + 𝐸 𝑆𝑖𝑃𝑀2 Detector unit Detector module (32 detector units) Couple material optimized in our previous work (Zhonghua Kuang et al 2018 Phys. Med. Biol. 63 045009).

II. Detector Design and Measurements Readout electronics Row and column readout 64 chs-> 16 chs 𝑥= 𝑖=1 𝑛 𝑖× 𝐸 𝑐𝑜𝑙 (𝑖) 𝑖=1 𝑛 𝑖× 𝐸 𝑐𝑜𝑙 (𝑖) + 𝑖=1 𝑛 (𝑛−𝑖+1)× 𝐸 𝑐𝑜𝑙 (𝑖) 𝑦= 𝑖=1 𝑚 𝑖× 𝐸 𝑟𝑜𝑤 (𝑖) 𝑖=1 𝑚 𝑖× 𝐸 𝑟𝑜𝑤 (𝑖) + 𝑖=1 𝑚 (𝑚−𝑖+1)× 𝐸 𝑟𝑜𝑤 (𝑖) 𝐷𝑂𝐼 𝑅𝑎𝑡𝑖𝑜= 𝐸 𝑐𝑜𝑙 (2𝑗) 𝐸 𝑐𝑜𝑙 2𝑗−1 + 𝐸 𝑐𝑜𝑙 (2𝑗)

II. Detector Design and Measurements Experimental setup A LYSO slab detector (1.0 mm thick) and a 22Na point source (0.25 mm diameter) were mounted on a translation table. Experiments were performed in both singles and coincidence modes. In singles mode, the whole array can be irradiated uniformly. In coincidence mode, a specific depth (2mm, 6mm 10mm 14mm and 18mm) is irradiated by using electronic collimation.

III. Results Flood & DOI profiles in singles mode Flood histogram (clearly resolved) DOI histograms (all pairs)

III. Results DOI profiles of detector unit 2 (left) and unit 15 (right) measured at five depths of 2, 6, 10, 14 and 18 mm. Unit 2 Unit 15

III. Results DOI resolution (E>400 keV) Average DOI resolution: 4.62±0.59 mm

III. Results Energy spectrum and resolution Crystal No. 2 Average energy resolution: 13.5±1.7 %

III. Results Timing spectrum and resolution (E> 400 keV) Whole array Average timing resolution: 518±28 ps

IV. Conclusions Performance of the proposed detector module The SiPM readout circuit will be further simplified and improved to obtain a better timing resolution in the future. The proposed DOI detector module can be used to build high performance whole body and total body PET scanners. DOI resolution All events 5.27 ± 0.62 mm E > 400 keV 4.62 ± 0.59 mm Energy resolution 13.5 ± 1.7 % Timing resolution (E > 400 keV) 518 ± 28 ps Let me make a conclusion for the performance of the three measured detectors by using the following table.

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