Analysis of lead oxide (PbO) layers for direct conversion X-ray detection

Lead oxide (PbO) is a candidate direct conversion material for medical X-ray applications. We produced various samples and detectors with thick PbO layers. X-ray performance data such as dark current, charge generation yield and temporal behavior were evaluated on small samples. The influence of the metal contacts was studied in detail. We also covered large a-Si thin-film transistor (TFT)-plates with PbO. Imaging results from a large detector with an active area of 18 cm × 20 cm are presented. The detector has 960 × 1080 pixels with a pixel pitch of 184 ?m. The modulation transfer function at the Nyquist frequency of 2.72 linepairs/mm is 50%. Finally, a full size X-ray image is presented

Congenital rubella syndrome and autism spectrum disorder prevented by rubella vaccination - United States, 2001-2010

<p>Abstract</p> <p>Background</p> <p>Congenital rubella syndrome (CRS) is associated with several negative outcomes, including autism spectrum disorders (ASDs). The objective of this study was to estimate the numbers of CRS and ASD cases prevented by rubella vaccination in the United States from 2001 through 2010.</p> <p>Methods</p> <p>Prevention estimates were calculated through simple mathematical modeling, with values of model parameters determined from published literature. Model parameters included pre-vaccine era CRS incidence, vaccine era CRS incidence, the number of live births per year, and the percentage of CRS cases presenting with an ASD.</p> <p>Results</p> <p>Based on our estimates, 16,600 CRS cases (range: 8300-62,250) were prevented by rubella vaccination from 2001 through 2010 in the United States. An estimated 1228 ASD cases were prevented by rubella vaccination in the United States during this time period. Simulating a slight expansion in ASD diagnostic criteria in recent decades, we estimate that a minimum of 830 ASD cases and a maximum of 6225 ASD cases were prevented.</p> <p>Conclusions</p> <p>We estimate that rubella vaccination prevented substantial numbers of CRS and ASD cases in the United States from 2001 through 2010. These findings provide additional incentive to maintain high measles-mumps-rubella (MMR) vaccination coverage.</p

Linear system models for lag in flat dynamic x-ray detectors

The detective quantum efficiency (DQE) is regarded as a suitable parameter to assess the global imaging performance of an x-ray detector. However, residual signals increase the signal-to-noise ratio and therefore artificially increase the measured DQE compared to a lag-free system. In this paper, the impact of lag on the DQE is described for two different sources of lag using linear system models. In addition to the commonly used temporal filtering model for trapping, an increase of the dark current is considered as another potential source of lag. It is shown that the assumed lag model has a crucial impact on the choice of an adequate lag estimation method. Examples are given using the direct conversion material PbO. It turns out that the most general approach is the evaluation of the temporal noise power spectrum. A new algorithm is proposed for the crucial issue of robustly estimating the power spectrum at frequency zero

Analysis of lead oxide (PbO) layers for direct conversion X-ray detection

Lead oxide (PbO) is a candidate direct conversion material for medical X-ray applications. We produced various samples and detectors with thick PbO layers. X-ray performance data such as dark current, charge generation yield and temporal behavior were evaluated on small samples. The influence of the metal contacts was studied in detail. We also covered large a-Si thin-film transistor (TFT)-plates with PbO. Imaging results from a large detector with an active area of 18 cm × 20 cm are presented. The detector has 960 × 1080 pixels with a pixel pitch of 184 ?m. The modulation transfer function at the Nyquist frequency of 2.72 linepairs/mm is 50%. Finally, a full size X-ray image is presented