<title>New Method For The Experimental Determination Of The Detective Quantum Efficiency Of X-Ray Screens</title>

Abstract

We have developed a new experimental method to determine the detective quantum efficiency (DQE) of any given x-ray screen for different x-ray energies. This method employs fast (10 ns) counting and coincidence techniques to directly measure the number, m, of photons emitted from the screen per absorbed x ray, and to determine both the statistical distribution and average value of m. These experimental data have been obtained for a calcium tungstate and a rare earth oxysulfide screen with quasi-monoenergetic x-ray beams in the region from approximately 15 to 70 keV. Examples of the experimental DQE values obtained from these measure-ments for pairs of the two types of screens respectively are 0.86 and 0.75 at an x-ray energy of 18 keV, and 0.20 and 0.41 at an x-ray energy of 69 keV. These results indicate a reversal in the relative capabilities of the screens to transfer image information such that there would be a preference for the calcium tungstate screen at 18 keV and the rare earth oxysulfide screen at 69 keV.© (1980) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.