The next Imaging and Optical Physics (IOP) meeting will be run as a Zoom webinar at 11 am (AEST) on Thursday, 9th July 2020. The presenters will be Dr Andrew Morgan (the University of Melbourne) and Dr Marcus Kitchen (Monash University).Please click this URL to start https://monash.zoom.us/j/96500980966 Or, go to https://monash.zoom.us/join and enter meeting ID: 965 0098 0966
Agenda for the IOP webinar, 9 July 2020
11:00 - 11:30 am
Speaker: Andrew Morgan (The University of Melbourne)
Title: Single Particle Imaging with X-ray Free-Electron Lasers
Abstract: For decades the potential for Free-Electron Lasers (FELs) to offer damage free, time and conformationally resolved images of single biological molecules in their native state has been known. Indeed this was one of the major motivating factors for their construction. But until recently, scientific studies using FELs have focused on imaging large molecular ensembles, in the form of crystals, solid or liquid state materials or gases. Recent results from the single particle imaging initiatives at the LCLS and the European XFEL have shown that it is now possible to image the 3D electron density of single biological particles with sizes in the range of 60-200 nm (at a resolution of about 10 nm). The prospect of imaging single protein molecules (<10 nm) at more biologically relevant length scales (< 1-2 nm) rests on the ability to analyse diffraction patterns where we can expect to measure only a few photons per snapshot. We present some recent results, including a background aware phasing algorithm.
11:30 am - 12:00 noon
Speaker: Marcus Kitchen (Monash University)
Title: Dark Field Imaging for Quantitative Porosity Measurement and its application to Pulmonary Medicine
Abstract: We have developed an analyser-based phase contrast X-ray imaging technique to measure the mean length scale of pores or particles that cannot be resolved directly by the system. By combining attenuation, phase and ultra-small angle X-ray scattering (dark field) information, the technique was capable of measuring differences in airway dimension between lungs of healthy mice and those with mild and severe emphysema. Our measurements of airway dimensions from 2D images showed a 1:1 relationship to the actual airway dimensions measured using micro-CT. Using 80 images, the sensitivity and specificity were measured to be 0.80 and 0.89, respectively, with the area under the ROC curve close to ideal at 0.96. Reducing the number of images to 11 slightly decreased the sensitivity to 0.75 and the ROC curve area to 0.90, whilst the specificity remained high at 0.89.
