A novel PET image system for non-pure positron emitters: A Monte Carlo Simulation study

• Main Authors: Lu, Shih-Chi, 呂世紀
• Other Authors: Chuang, Keh-Shih
• Format: Others
• Language: zh-TW
• Published: 2009
• Online Access: http://ndltd.ncl.edu.tw/handle/37634987108466165633

碩士 === 國立清華大學 === 生醫工程與環境科學系 === 97 === Non-pure positron emitters (e.g. I-124，Br-76，Y-86) have advantages with longer half-lives which can provide prolong study and target specific properties. However, these isotopes also emit high energy gamma rays (called associated gamma) that can be detected and cause additional random coincidences with the annihilation photons. In this research, we propose a novel imaging system called non-pure positron emission tomography (NPET). The system is based on the idea that the source position can be determined through detection of the three photons (2 annihilation photons and 1 associated gamma) using a triple coincidence circuit. The system comprises of two parts. NPET comprises of mutual perpendicular PET and SPECT connected by a coincidence circuit. The collimator on the SPECT can be used to detect the direction of the associated gamma. As long as these three photons are detected in the same time, the source position is located on the intersection of the incoming direction of the associated gamma and the line of annihilated photons which can provide real time image. The simulation results demonstrated the feasibility of the novel PET imaging for non-pure positron emitters. The average system resolution for NPET is 3.6 mm and the sensitivity is about 69 cps/MBq. Although the scatter and random effect dominate the located source positions which degrade the image quality, NPET system is in initial stage so that it could be improved and developed variously in the future.