TY - JOUR T1 - Improving sensitivity of endoscopy-based Cerenkov luminescence imaging system using Gd<sub>2</sub>O<sub>2</sub>S:Tb JF - Journal of Nuclear Medicine JO - J Nucl Med SP - 1868 LP - 1868 VL - 56 IS - supplement 3 AU - Xin Cao AU - Xueli Chen AU - Fei Kang AU - Xu Cao AU - Jing Wang AU - Kaichun Wu AU - Jimin Liang Y1 - 2015/05/01 UR - http://jnm.snmjournals.org/content/56/supplement_3/1868.abstract N2 - 1868 Objectives Our previous study showed a severe attenuation of Cerenkov luminescence (CL) intensity in the endoscopy-based CL imaging (ECLI) system, which deteriorates its detection sensitivity. Here, a radioluminescence microparticles (RLMPs) based strategy was presented to improve sensitivity of ECLI system and validated with an in vitro experiment.Methods The ECLI system was the same as that used in previous study. The RLMPs used here was Gd2O2S:Tb. A single well of black 96-well plate (300 µl per well) was filled with normal saline that was mixed with 37 KBq 68Ga and 1 mg RLMPs. After white-light image was taken with an exposure time of 1 s, the luminescent images were successively acquired with an integration time of 5 min for each image. The total acquisition time was 360 min.Results Figure 1(A) shows the sequential images of the well that contains the mixture, acquired over the decay of radionuclide. A region of interest (ROI) was extracted from each image, and the average intensity (AI) of the ROIs was calculated. Figure 1(B) depicts the AI of the ROIs as a function of the activity of 68Ga, and the signal to background ratio (SBR) as a function of the activity of 68Ga is given in Figure 1(C). From Figure 1(B) and 1(C), a minimum activity of 3.48×10-3 KBq/µl can be identified from the background (SBR &gt; 1).Conclusions Our previous study showed that the in vitro sensitivity of ECLI system was 0.186 KBq/µl. With the help of RLMPs, the minimum activity detected by ECLI system is promoted to 3.48×10-3 KBq/µl, a 53-fold improvement. Even for the SBR larger than 2, the activity is lower than 9.28×10-3 KBq/µl, still larger than the activity gathered around gastrointestinal tumors for clinical diagnosis (5.55×10-2 KBq/µl). We believe that the RLMPs based sensitivity enhancement strategy may overcome the sensitivity limitation of ECLI system in clinical application.Research Support This work was partly supported by the Program of National Basic Research and Development Program of China (973) under Grant No. 2011CB707702, the National Natural Science Foundation of China under Grant Nos. 81090272, 81227901, 81101083, 81230033, 61405149, 81401442, the Open Research Project under Grant 20120101 from SKLMCCS, and the Fundamental Research Funds for the Central Universities. ER -