title: Improving signal to noise in labeled biological specimens using energy-filtered TEM of sections with a drift correction strategy and a direct detection device.
abstract: Energy filtered transmission electron microscopy techniques are regularly used to build elemental maps of spatially distributed nanoparticles in materials and biological specimens. When working with thick biological sections, electron energy loss spectroscopy techniques involving core-loss electrons often require exposures exceeding several minutes to provide sufficient signal to noise. Image quality with these long exposures is often compromised by specimen drift, which results in blurring and reduced resolution. To mitigate drift artifacts, a series of short exposure images can be acquired, aligned, and merged to form a single image. For samples where the target elements have extremely low signal yields, the use of charge coupled device (CCD)-based detectors for this purpose can be problematic. At short acquisition times, the images produced by CCDs can be noisy and may contain fixed pattern artifacts that impact subsequent correlative alignment. Here we report on the use of direct electron detection devices (DDD's) to increase the signal to noise as compared with CCD's. A 3× improvement in signal is reported with a DDD versus a comparably formatted CCD, with equivalent dose on each detector. With the fast rolling-readout design of the DDD, the duty cycle provides a major benefit, as there is no dead time between successive frames.
authors.affiliation: Center for Research in Biological Systems,National Center for Microscopy and Imaging Research,University of California at San Diego,9500 Gilman Dr.,La Jolla,CA 92093,USA.
authors.forename: Ranjan
authors.initials: R
authors.lastname: Ramachandra
authors.affiliation: Center for Research in Biological Systems,National Center for Microscopy and Imaging Research,University of California at San Diego,9500 Gilman Dr.,La Jolla,CA 92093,USA.
authors.forename: James C
authors.initials: JC
authors.lastname: Bouwer
authors.affiliation: Center for Research in Biological Systems,National Center for Microscopy and Imaging Research,University of California at San Diego,9500 Gilman Dr.,La Jolla,CA 92093,USA.
authors.forename: Mason R
authors.initials: MR
authors.lastname: Mackey
authors.affiliation: Center for Research in Biological Systems,National Center for Microscopy and Imaging Research,University of California at San Diego,9500 Gilman Dr.,La Jolla,CA 92093,USA.
authors.forename: Eric
authors.initials: E
authors.lastname: Bushong
authors.affiliation: Center for Research in Biological Systems,National Center for Microscopy and Imaging Research,University of California at San Diego,9500 Gilman Dr.,La Jolla,CA 92093,USA.
authors.forename: Steven T
authors.initials: ST
authors.lastname: Peltier
authors.affiliation: Center for Research in Biological Systems,National Center for Microscopy and Imaging Research,University of California at San Diego,9500 Gilman Dr.,La Jolla,CA 92093,USA.
authors.forename: Nguyen-Huu
authors.initials: NH
authors.lastname: Xuong
authors.affiliation: Center for Research in Biological Systems,National Center for Microscopy and Imaging Research,University of California at San Diego,9500 Gilman Dr.,La Jolla,CA 92093,USA.
authors.forename: Mark H
authors.initials: MH
authors.lastname: Ellisman
mesh_terms: D000818:Animals; D001253:Astrocytes / Q000648:ultrastructure*; D001921:Brain / Q000473:pathology; D004847:Epithelial Cells / Q000648:ultrastructure*; D006367:HeLa Cells; D006801:Humans; D008810:Mice, Inbred C57BL; D046032:Microscopy, Energy-Filtering Transmission Electron / Q000295:instrumentation* / Q000379:methods*; D059629:Signal-To-Noise Ratio; D013194:Staining and Labeling / Q000379:methods*