James F. Owen

Storage phosphor X-ray diffraction detectors

Abstract The use of photostimulable storage phosphors as area detectors for X-ray diffraction is described. The elements of a basic acquisition system are explained and the principles of operation are reviewed. A simple model for the transfer of system signal and noise is derived, allowing determination of the detective quantum efficiency (DQE). Using this model, predicted storage phosphor performance can be compared with conventional detector technologies for tasks in X-ray diffraction.

Protein crystallographic data acquisition and preliminary analysis using kodak storage phosphor plates

Abstract X-ray diffraction data from single crystals of typical proteins are very weak, numerous, and subject to systematic errors arising from radiation damage at long exposure times. Compared with films, the Kodak storage phosphor technology described in the accompanying paper [1] offers the prospect of greatly improved signal-to-noise, increased sensitivity particularly at shorter wavelengths, and wide dynamic range, though with more modest spatial resolution. To assess the suitability of this technology for protein crystallographic data collection, we have collected both monochromatic oscillation and wide bandpass Laue data at CHESS on crystals ranging in unit cell size from ∼ 50 A (lysozyme) to ∼ 300 A (viruses). A direct comparison of the Kodak storage phosphor with conventional Kodak Direct Exposure Film (DEF-5) was obtained by making immediately sequential exposures on the same crystal with the two detector systems. Even with an exposure time one order of magnitude less than with the corresponding film, the storage phosphor yielded data with improved signal-to-noise. Thus, storage phosphors enable more data to be acquired per crystal, with less radiation damage, and with better precision. Such detectors appear extremely well suited to protein crystallographic applications, both static and time-resolved, with both monochromatic and polychromatic X-ray sources.

Storage Phosphor System For Computed Radiography: Screen Optics

A model for light scattering and absorption effects is applied to a system for computed radiography in which a turbid photostimulable phosphor is scanned with a laser. The spatial spreading of the laser light and the escape probability of the stimulated light are important in determining system response, and models for their effects are presented. Model calculations of system MTF are compared with measured data.

Storage Phosphor System For Computed Radiography: Destructive Scanning

A particular system for computed radiography uses a photostimulable phosphor which is scanned by a laser that reads and also erases the storage medium. The process of reading and erasing is called destructive scanning, and a model of its effects is presented here. Model predictions of system dc gain vs. scanning exposure for the case of raster scanning with a Gaussian beam are compared with measured data.