TY - JOUR T1 - Direct Imaging of Radionuclide-Produced Electrons and Positrons with an Ultrathin Phosphor JF - Journal of Nuclear Medicine JO - J Nucl Med SP - 1141 LP - 1145 DO - 10.2967/jnumed.107.040568 VL - 49 IS - 7 AU - Liying Chen AU - Lisa S. Gobar AU - Negar G. Knowles AU - Zhonglin Liu AU - Arthur F. Gmitro AU - Harrison H. Barrett Y1 - 2008/07/01 UR - http://jnm.snmjournals.org/content/49/7/1141.abstract N2 - Current electron detectors are either unable to image in vivo or lack sufficient spatial resolution because of electron scattering in thick detector materials. This study was aimed at developing a sensitive high-resolution system capable of detecting electron-emitting isotopes in vivo. Methods: The system uses a lens-coupled charge-coupled-device camera to capture the scintillation light excited by an electron-emitting object near an ultrathin phosphor. The spatial resolution and sensitivity of the system were measured with a 3.7-kBq 90Y/90Sr β-source and a 70-μm resin bead labeled with 99mTc. Finally, we imaged the 99mTc-pertechnetate concentration in the mandibular gland of a mouse in vivo. Results: Useful images were obtained with only a few hundred emitted β particles from the 90Y/90Sr source or conversion electrons from the 99mTc bead source. The in vivo image showed a clear profile of the mandibular gland and many fine details with exposures of as low as 30 s. All measurements were consistent with a spatial resolution of about 50 μm, corresponding to 2.5 detector pixels with the current camera. Conclusion: Our new electron-imaging system can image electron-emitting isotope distributions at high resolution and sensitivity. The system is useful for in vivo imaging of small animals and small, exposed regions on humans. The ability to image β particles, positrons, and conversion electrons makes the system applicable to most isotopes. ER -