PETCT基本原理和应用课件.ppt

Outline Overview 功能与解剖成像 PET系统的发展历史 PET物理学基础 符合探测 “混合”事件 分辨率和噪声 衰减校正 PET主机的组成和工作原理 计算机图象处理 质量控制 Medical Imaging Center,Fuzhou General Hospital 整套PET系统包括PET主机和回旋加速器及配套的化学合成装置三大部分。 PET主机配置有扫描机架、主机柜、检查床、主辅工作站等几个部分。 机架是最大部分，其中最主要的是探头部分，包括探测器环和中隔、多晶体、光电倍增管、前置电子线路、符合线路、分类器、电子准直线路、透射源及各种电子学仪器线路等。 Medical Imaging Center,Fuzhou General Hospital Medical Imaging Center,Fuzhou General Hospital Medical Imaging Center,Fuzhou General Hospital Medical Imaging Center,Fuzhou General Hospital Detector Requirements Goal Requirement High Spatial Resolution Small Detector Elements High Sensitivity High Stopping Power Low Scatter Fraction Good Energy Resolution Low Randoms Good Timing Resolution Low Deadtime Fast Event Handling Small Channel Size Limited Multiplexing Low Cost None of the Above Medical Imaging Center,Fuzhou General Hospital Detector Materials High Density Overall detection efficiency is proportional to the product of the detection efficiencies High Effective Atomic Number High photopeak fraction (photopeak vs Compton) allows high discriminator setting for scatter rejection Fast Decay Time The primary speed of the detector has a big effect on count rate Others light output, wavelength, and index of refraction are other properties that are important Medical Imaging Center,Fuzhou General Hospital Detector Materials NaI(Tl) BGO GSO(Ce) LSO(Ce) STOPPHOTONS PRODUCE LIGHT GROW CRYSTALS m(cm-1) 0.37 0.95 0.67 0.89 Photonfraction ~15% ~40% ~35% ~30% Light Output 100 20-25 35 75 Decay Constant 230 300 65 50 Radioactive NO NO NO YES Melting Point 650 1050 >2000 >2000 Furnace Platinum Iridium Iridium Cost $5/cc $10/cc $20/cc >$25/cc ?? Medical Imaging Center,Fuzhou General Hospital Detector Assemblies 1-to-1 Coupling Excellent livetime characteristics, but expensive, and limited in size to sm